Rpd Group Reporting Compilation PDF

GROUP 1 SALUDES, Mike Daimler AGAPAY, Marielle Jois CABOLES, Jlykah CAPIT, Althea Joyce GUBATAN, Shellie Shiyah RAMOS, Reanne Joyce TAYAMIN, Genicel Final Impression and Fabrication of Master Cast I. FINAL IMPRESSION The last detailed mold or cast taken on a patient’s oral...

GROUP 1 SALUDES, Mike Daimler AGAPAY, Marielle Jois CABOLES, Jlykah CAPIT, Althea Joyce GUBATAN, Shellie Shiyah RAMOS, Reanne Joyce TAYAMIN, Genicel Final Impression and Fabrication of Master Cast I. FINAL IMPRESSION The last detailed mold or cast taken on a patient’s oral structures before the fabrication of the denture the final impression is typically made after preliminary impressions and any necessary adjustments have been made to ensure a more accurate and comfortable fit WHAT TO CHECK ON FINAL IMPRESSION? Absence of significant voids when there are voids, it can lead to poor-fitting dentures, and it can negatively impact the overall success of the rpd Well-defined peripheries There must be an Accurate record of supporting tissues Integrity of the impression this can ensure retention, stability, and if there’s a compromised integrity, it can result to functional problems Allows incorporation of all design elements No significant areas of “burn-through” ○ This is really important as it can compromise the integrity and strength of the denture, leading to breakage and discomfort We must ensure that the final impression Records Critical Anatomies like Frenal attachments Vestibular depths Hamular notches Vibrating Line Retromolar pads Floor of the mouth The success of the RPD is largely dependent on accuracy of impression, which requires good understanding of anatomical landmarks and physiology of supporting structure in addition to understanding the properties and manipulation of different impression materials. 3 FEATURES (Evaluation of Impression Materials) To capture accurate and precise details to ensure proper fit and comfort, since any inaccuracies can result to a compromised function It must be strong at the time of removal from the mouth In order to obtain a better retention and support for the final restoration, which provides an overall more reliable foundation for the prosthetic work. Appropriate material selection which is a key to the success of the final impression II. MATERIALS 1. Elastic Materials a. Reversible hydrocolloids- Fluid at higher temperatures and gel on reduction in temperature. Used primarily as impression materials for fixed restorations. Advantages offer accuracy and detail compared to other impression materials like irreversible hydrocolloids and synthetic elastomeric materials. easy to use, requiring only heating and cooling to achieve the desired consistency. Disadvantages Low Tear Strength: making them less suitable for impressions in narrow deep sulcus. Sensitivity to Temperature Changes: susceptible to dimensional changes due to temperature fluctuations. Not Suitable for All Impressions: especially those requiring high dimensional stability or resistance to distortion. b. Irreversible hydrocolloids - the most commonly used due to ease of handling, relatively low cost, and generating of dependable, accurate dental stone casts when properly manipulated. Have low tear strength, provide less surface detail than other materials and are not as dimensionally stable as others. Can be used in the presence of moisture, are hydrophilic, pour well with stone, have a pleasant taste and odor, and are nontoxic & nonstaining. Advantages Cost-effectiveness:cheaper than other impression materials Hydrophilic nature: readily wets the tooth surface, minimizing air bubbles and ensuring accurate detail reproduction, even in the presence of saliva. Comfortable for patients: as it sets quickly and does not cause significant discomfort.  Disadvantages Dimensional instability: susceptible to syneresis, the loss of water from the gel, and imbibition, the absorption of water from the surrounding environment. Short working time: requiring prompt manipulation and impression placement. Potential for tear strength issues: can be prone to tearing, especially when removed from the mouth slowly or when the impression is thin c. Mercaptan Rubber - base Impression Materials -can also be used for RPD impressions and especially for secondary corrected or altered cast impressions. To be accurate, the impression must have a uniform thickness that does not exceed 3 mm Advantages High accuracy: known for their ability to capture fine details. Dimensional stability: it retains its shape over time, minimizing distortion and ensuring accurate casts. Good tear resistance: resistant to tearing, even when removed from the mouth slowly or when the impression is thin. Disadvantages Unpleasant odor and taste: emits a strong sulfur-like odor and has a disagreeable taste. Long setting time: The setting time for this material is relatively long. Staining: can stain clothing and other materials. Hydrophobic nature: it repels water, which can make it difficult to pour in stone. d. Polyether Impression Materials - Demonstrated good accuracy in clinical evaluations and are thixotropic, which provides good surface detail and makes them useful as a border molding material. Hydrophilic, and have low to moderate tear strength and much shorter working and setting times, which can limit the usefulness of the material. e. Silicone Impression Materials - more accurate and easier to use than the other elastic impression materials. Have a pleasant odor, moderately high tear strength, and excellent recovery from deformation. Hydrophobic and can be disinfected in any of the disinfecting solutions with no alteration in accuracy. Ideally should be poured within 1 hour. 2. Rigid materials a. Plaster of paris - impression plaster or Type I gypsum has been used in dentistry for over 200 years. Plaster of Paris was once the only material available for RPD impressions, but now elastic materials have completely replaced the impression plasters in this phase of prosthetic dentistry. Advantages Accuracy and Detail: known for its ability to reproduce fine details. Cost-Effectiveness: inexpensive compared to other materials. Easy Handling and Manipulation: Fast Setting Time: typically within 30 to 45 minutes. Biocompatibility: it is safe for use in contact with the oral tissues. Disadvantages Brittleness: relatively brittle and can easily break or chip, especially when handling delicate models or impressions. Water Sensitivity: susceptible to water damage and can deteriorate if exposed to moisture for extended periods. b. Metallic oxide paste - Usually some form of a zinc oxide-eugenol combination - Not used as primary impression materials and should never be used for impressions that include remaining natural teeth. - Can be used as secondary impression materials for complete dentures and for extension base edentulous ridge areas of RPD if a custom impression tray has been properly designed and attached to the removable partial denture framework. Advantages: Improved Accuracy and Detail: Enhanced Mechanical Properties: could improve the strength, flexibility, and tear resistance of impression materials. Disadvantages: Limited Research: More studies are needed to fully understand their effectiveness, long-term effects, and potential drawbacks. Aesthetic Concerns: causes discoloration of the impression material, affecting the aesthetic appearance of the model. 3. Thermoplastic Materials a. Modeling Plastic - among the oldest impression materials used in prosthetic dentistry like the plaster of paris. - most often used for border correction (border molding) of custom impression trays for Kennedy Class I and Class II removable partial denture bases. Cake form:  ○ red (red-brown) material: most commonly used modeling plastic for corrected impressions of extension base areas, softens at about 132° F. Stick form: ○ green material: lowest fusing of the modeling plastics. ○ red and gray sticks: have a higher and broader working range than do the cakes of like color so they may be flamed without harming the material. Advantages ○ Low Cost: ○ Easy Manipulation: It is easy to soften and manipulate, allowing for adjustments and corrections to be made to the impression. ○ Reversible: The ability to soften and re-harden allows for corrections and adjustments to be made to the impression, ensuring a more accurate fit. Disadvantages ○ Limited Accuracy: not as accurate as other impression materials. ○ Rigid: Its rigidity can make it difficult to record undercuts. b. Impression waxes and Natural resins - More commonly known as mouth-temperature waxes. - Most familiar of these have been the Iowa wax and the Korecta waxes, all of which were developed for specific techniques. - may also be used to correct the borders of impressions made of more rigid materials, thereby establishing optimum contact at the border of the denture. Advantages Low Cost: Ease of Use: Reversible: Disadvantages Limited Accuracy: Distortion: prone to distortion, especially when removed from undercuts. Poor Dimensional Stability: meaning they can shrink or expand over time. III. FABRICATION OF MASTER CAST Step-by-step Procedure for Making a Stone Cast from a Hydrocolloid Impression abrasive resistant type IV stone room temp. water spatula & no. 7 spatula vibrator 1. Mixing and Initial Preparation ○ Mix the water and stone thoroughly for 1 minute to ensure a smooth, homogenous consistency. ○ Place the bowl on the vibrator to release trapped air. 2.. Preparing the Impression ○ Remove the impression from the damp towel and shake off excess moisture. ○ Hold the impression over the vibrator with only the handle touching it. 3. Incremental Filling of the Impression ○ Begin pouring stone at the distal end, allowing it to flow naturally. ○ Add small increments, allowing each layer to push the previous one. ○ Gradually increase the portions until the impression is filled. 4. Supporting and Completing the Base ○ Ensure the cast's base is 16–18 mm thick at its thinnest portion. ○ Extend the base beyond the impression borders to capture all anatomical landmarks. 5. Trim the Excess and Maintain Humidity ○ Trim any excess stone from the sides of the cast. Wrap the impression and cast in a wet paper towel or place them in a humidor. 6. Separate the Cast After Initial Setting ○ Allow the cast and impression to remain in a humid environment for 30 minutes. Trim interfering stone with a knife before separating the impression from the cast. 7. Clean the Impression Tray Immediately ○ Clean the impression tray while the impression material is still elastic. 8. Final Trimming of the Cast ○ Wait until the cast is fully set before performing final trimming. Trim the sides to make them parallel and remove air bubble defects (blebs). IV. MARKINGS ON THE MASTER CAST a) Location of retentive arm for a c-clasp Position: The retentive arm is located on the buccal or facial surface of the abutment tooth. It starts above the height of contour and extends down to the undercut area below it. Placement Details: The tip of the retentive arm engages the undercut area below the height of contour. Function: Provides retention by engaging an undercut, preventing the RPD from dislodging during function. b) Location of retentive arm for a bar clasp Position: Located on the buccal or labial surface, starting below the survey line. Placement Details: The arm approaches the tooth from a gingival direction. Function: Provides retention with minimal tooth coverage for improved esthetics. c) Parallel projections on the axial surfaces of the cast Refers to guiding planes, which are flat, parallel surfaces prepared on the axial surfaces of abutment teeth or on proximal surfaces Typically on proximal surfaces of abutment teeth adjacent to edentulous spaces Recorded using tripoding technique The lines should be parallel to the path of insertion and should be drawn on three sides of the cast to ensure stability and preventing unwanted movement during use. d) Beading A shallow groove or marking on the cast used to create a seal at the border of the major connector, especially for maxillary RPDs. This is done only for the maxillary cast to get a good seal Depth: About 0.5 mm deep and wide. e) Location of rests Placed in prepared rest seats on the occlusal, cingulum, or incisal areas of abutment teeth. By marking these with a colored pencil, it serves as a reduction guide and helps in the proper placement and design of rest needed in the framework. Purpose: To prevent the denture base from moving cervically and impinging gingival tissue f) Location of finishing lines The location of finishing lines minimizes the bulk of resin attaching the artificial teeth. Hence, palatal contours are restored, enhancing speech and contributing to a natural feeling of a patient. g) Location of tissue stop Position: Located at the distal extension of the denture base in distal extension RPDs Purpose: ○ Stabilizes the framework during processing. ○ Prevents distortion of the metal framework. h) Height of contour on the teeth and soft tissue created during the survey of the cast The height of contour is the widest part of the tooth or tissue surface, identified during the surveying process. Location: ○ For teeth: Found on the facial and lingual surfaces of abutment teeth. ○ For soft tissue: May be identified to assess undercut areas near the alveolar ridge. Purpose: ○ Determines the path of insertion. ○ Identifies areas of undercut for clasp placement V. SURVEYING THE MASTER CAST Surveying in Prosthodontics: The process of analyzing a dental cast to find the best path for inserting and removing a removable partial denture (RPD). It identifies undercuts for retention and areas needing adjustment for a better fit. Dental Surveyor: A tool used to mark the height of contour on teeth, locate areas for adjustment, and plan the placement of clasps and other denture components. After mouth preparations, the master cast is surveyed to determine the path of placement, identify retentive areas, and locate any remaining interferences. Surveying the master cast is essential to ensure the proper design and fit of the denture framework. It helps: 1. Determine the path of placement – Ensuring the framework aligns correctly during insertion and removal. 2. Identify retentive areas – Locating undercuts for optimal retention. 3. Detect interferences – Addressing areas that might hinder proper fit or function. 4. Guide framework design – Providing a blueprint for a stable, functional, and comfortable denture. Objective of surveying the master cast: 1. To select the most suitable path of placement by following mouth preparations that satisfy the requirements of guiding planes, retention, noninterference, and esthetics. 2. To permit measurement of retentive areas and to identify the location of clasp terminals in proportion to the flexibility of the clasp arm being used: Flexibility depends on many of the following factors: a) the alloy used for the clasp, b) the design and type of clasp, c) whether its form is round or half-round, d) whether it is of cast or wrought material, and e) the length of the clasp arm from its point of origin to its terminal end. 3. To locate undesirable undercut areas that will be crossed by rigid parts of the restoration during placement and removal: These must be eliminated by blockout. 4. To trim blockout material parallel to the path of placement before duplication The partial denture must be designed so that 1) it will not stress abutment teeth beyond their physiologic tolerance, 2) it can be easily placed and removed by the patient, 3) it will be retained against reasonable dislodging forces, and 4) it will not create an unfavorable appearance. It is necessary that the diagnostic cast be surveyed with these principles in mind. Mouth preparation should therefore be planned in accordance with certain factors that will influence the path of placement and removal. What is the proper way in SURVEYING: the master cast - The master cast must be surveyed as a new cast, but the prepared proximal guiding plane surfaces will indicate the correct anteroposterior tilt. - - The lateral tilt will be the position that provides equal retentive areas on all principal abutments in relation to the planned clasp design. - - The base of the cast is now scored, or the cast is tripoded as described previously. The surveyor is used with the master cast for two purposes: (1) to delineate the height of contour of the abutment teeth both to locate clasp arms and to identify the location and magnitude of retentive undercuts; and (2) to trim blockout of any remaining interference to placement and removal of the denture. Measuring the Retention of Master Cast: (1) the magnitude of the angle of cervical convergence below the point of convexity; (2) the depth at which the clasp terminal is placed in the angle; and (3) the flexibility of the clasp arm. VI. BLOCKING OUT THE MASTER CAST BLOCKOUT - is defined as, “Elimination of undesirable undercut areas on the cast to be used in the fabrication of the removable partial denture”. - It is the process by which the undesirable undercuts on the master cast are eliminated using wax. Since the undercuts are filled with wax, the refractory cast duplicated from the master cast will not have these undercuts. Blockout includes not only the areas crossed by the denture framework during seating and removal but also: 1. those areas not involved that are blocked out for convenience; 2. ledges on which clasp patterns are to be placed; 3. relief beneath connectors to avoid tissue impingement; and 4. relief to provide for attachment of the denture base to the framework. TYPES OF BLOCKOUT Parallel Blockout: ○ Ensures guiding planes are parallel. ○ This is the procedure by which undercuts below the height of contour of the existing teeth are eliminated in relation to that path of insertion. The master cast  is surveyed and the undercuts in relation to the determined path of insertion are marked. Shaped/ Ledge Blockout: ○ Creates ledges for clasp arms ○ This procedure is very special because it has a totally different purpose. It is done in the undercut of the primary abutment along the lower border of the proposed retentive arm. Arbitrary Blockout: ○ Covers non-essential areas to prevent interference. ○ This procedure involves filling the soft tissues and other unwanted undercuts in the cast with blockout wax. ○ The purpose of this procedure is to eliminate the unwanted undercuts (ridge, soft tissue), which may interfere with the path of insertion. ○ It is termed arbitrary blockout because the surface of the block out wax need not be parallel to the path of insertion RELIEF - It is defined as, “The procedure of placing a sheet of wax in strategic areas on the master cast to be duplicated so that a refractory cast can be made” - The purpose of relieving the master cast with wax is to provide space between certain components of the framework and the adjacent oral structures such as the minor connector to which the denture base will be attached.  - - Usually used beneath lingual bars and in other areas where major connectors will contact thin soft tissue such as maxillary and mandibular tori. - Relief under the gridwork should not be started immediately adjacent to the abutment tooth but should begin 1.5 - 2 mm from the abutment tooth. VII. HOW TO ILLUSTRATE YOUR DESIGN ON THE MASTER CAST? Design transfer is defined as, "Conveying the outline of the proposed prosthesis from the diagnostic cast to the master cast". Design Transfer includes the following steps: 1. Marking the height of contour 2. Measuring the undercut 3. Drawing the clasps 4. Drawing the connectors MARKING THE HEIGHT OF CONTOUR Procedure: - Place the master cast on a dental surveyor. - Use an analyzing rod to scribe a continuous line around each abutment tooth, indicating the height of contour. - Adjust the cast tilt as needed to achieve an optimal path of insertion. Why is it important? - This line determines the positioning of retentive and reciprocal clasp arms and ensures the framework aligns with the planned path of insertion. MEASURING THE UNDERCUT Procedure: - Replace the analyzing rod with an undercut gauge (e.g., 0.25mm, 0.5mm). - Pass the gauge along the surface of each abutment tooth, focusing below the height of contour. - Mark the undercut areas on the cast. Why is it important? - Accurately identifying and marking the undercuts ensures that the retentive clasps engage the tooth securely without applying excessive force. DRAWING THE CLASPS Procedure: - Retentive Arm: Begin below the height of contour in the marked undercut, extending upward toward the major connector. - Reciprocal Arm: Draw this arm above the height of contour on the opposite side to balance the retentive forces. - Include the locations of rests to ensure vertical support for the framework. Why is it important? - Properly positioned clasps distribute forces evenly and maintain the prosthesis's stability during function. Clasps are crucial for retention and stability. They must be drawn with precision on the master cast. DRAWING THE CONNECTORS Procedure: Study the Cast - Analyze the dental arch and identify the areas for major and minor connectors based on the RPD framework design. Mark the Borders - Outline the extent of the major connector on the cast, ensuring proper coverage for strength and support while avoiding impingement on soft tissues. Locate Minor Connectors - Identify and mark the paths for minor connectors connecting clasps and rests to the major connector. Consider Tissue Relief - Incorporate adequate relief spaces where necessary to avoid contact with delicate soft tissues. Ensure Symmetry - Maintain balance and symmetry in the connector design for stability and aesthetic appeal. Finalize the Design - Review the layout, ensuring connectors do not interfere with the function or comfort of the prosthesis. Why is it important? Connectors unite all components of the RPD and ensure it functions as a single unit. And connectors provide structural integrity and distribute functional forces across the arch. Before finalizing, double-check the design for: Adequate retention and support. Proper clearance from soft tissues. Integration with the patient’s occlusion. GROUP 2: ASPARELA, AIKHA ROCHELLE D. LOPEZ, ASAIAH FAITH DAYRIT, DIANNE CLOE B. UY, SHANDY MAE ALVERO ORTIZ, JASSEN SALAZAR CAMACHO, MA. JIMYELLE MYAN L. PESCADOR, MA. SUZANNE S. Wax Pattern with Work Authorization: Function & Characteristic DEFINITION OF WAX PATTERN ○ Wax pattern fabrication for a removable partial denture (RPD) is the process of creating a wax model that follows the profile of the design to create the final cast restoration. FUNCTION OF WAX PATTERN ○ It is essential to the dentist to understand the laboratory procedures involved. This enables them to design the RPD framework, complete a laboratory work authorization that communicates the desired design and authorizes its fabrication, and evaluate the quality of the framework. ○ Understanding and evaluation of the key features required in a completed removable partial denture framework ensures the patient of a chance to function comfortably with the finished product. METHODS OF WAXING a. Freehand A slow method of waxing No control of uniformity b. Wax patterns Faster than freehand More control of uniformity than freehand Do not compress patterns with much pressure or the pattern will distort c. Plastic patterns Excellent and fast method of waxing d. Combination Combines the best qualities of freehand, wax patterns and plastic patterns. PROCEDURE OF WAX PATTERN IN RPD 1. A sheet thickness of casting wax or plastic is cut to approximately outline of the major connector. 2. Extend the plastic or wax sheet up onto the lingual surface of teeth that are to be plated, stopping it just short of the outline. Then flow blue casting wax on edge to seal it to cast 3. Blue casting wax is flowed into beading where it should be about 1mm thick and taper out as it goes away from the bead. Width should be between 2 and 33 mm. Thin layer of wax may also be flowed across the palate in a cross form for reinforcement. 4. Tacky liquid is painted on refractory cast within the borders of the outline. It should not be painted on blue wax  5. Flow soft blue casting wax along the borders of the plastic sheet to seal it in place an fill in between the sheet and the outline. 6. Finish the wax to a thin edge when it goes onto the teeth, and leave it slightly rounded on the border of the major connector 7. Add wax for the denture base, which will be used to retain the pink plastic and the denture teeth. 8. Waxing the outer strut and cross strut. a. Outer strut - 9. Select the proper clasp form pass it through the flame the tissue side of the clasp is dampened with a tacky fluid adapt the form the tooth surface guided by the ledging the tip is positioned followed by the body. 10. The bar clasp should be attached and thickened where a cross strut attaches to the outer strut. 11. This will aid in providing space for the flow of metal to the bar clasp during the casting procedure WORK AUTHORIZATION ○ A written direction for the laboratory procedures to be performed in fabrication of any dental restoration by a laboratory technician. ○ Technician fabricates a restoration according to the dentist’s instructions. A. CONTENT Information contained in a work authorization should include the following: 1. The Name and Address of The Dental Laboratory; 2. The Name and Address of The Dentist Who Initiates The Work Authorization; 3. The Identification of The Patient; 4. The Date of Work Authorization; 5. The Desired Completion Date of The Request; 6. Specific Instructions; 7. The Signature of The Dentist; And 8. The Registered License Number of The Dentist. CHARACTERISTICS OF WORK AUTHORIZATION 1. A work authorization must be legible, clear, concise, and readily understood. 2. It is sound practice to provide the dental laboratory technician with adequate written instructions for each laboratory service required in the fabrication of a restoration 3. No single work authorization form is adequate to furnish detailed instructions for accomplishing the laboratory phases in the fabrication of removable partial dentures, crowns, and fixed partial dentures, or complete dentures, or for accomplishing orthodontic laboratory procedures. FUNCTION OF WORK AUTHORIZATION The following four important functions are performed by a work authorization: 1. It furnishes definite instructions for laboratory procedures to be accomplished and implies an expectation of a level of acceptable quality for the services rendered. 2. It provides a means of protecting the public from the illegal practice of dentistry. 3. It is a protective legal document for both the dentist and the dental laboratory technician.  4. It completely delineates the responsibilities of the dentist and the dental laboratory technician STEPS AND FEATURES OF WORK AUTHORIZATION 1. Only a minimum of writing is necessary to provide thorough instructions 2. The form can contain printed listings of materials and specifications that require either a checkmark or a fill-in for authorization of their use. 3. Includes drawing the design on a diagnostic cast. Exact location of rests, proximal plates, major/minor connectors, and clasps augment the written work authorization request 4. A reminder space is included to designate the choice of metal for the framework. Frameworks for removable partial dentures are usually cast in type IV gold, chromium-cobalt alloy, or a titanium alloy. The nature of the material of the denture base may also be indicated by a checkmark. 5. Space is reserved on the work authorization form to furnish the technician with information on the dentist’s selection of teeth. The responsibility for tooth selection must remain with the dentist. Tooth Shade Tooth Shape and Form Tooth Size 6. A display of courtesy deserved by and a demonstration of respect for the laboratory technician are indicated. The general request is prefaced by “please” and the specific instructions are ended with “thank you.” 7. Figures can be provided on which diagrams may be drawn to enhance written descriptions when necessary. 8. A color-code index can be used to explain the markings on the master cast when it is submitted to the laboratory for the fabrication of a framework. - Green - outline of the framework - Red - location of finish lines - Black - height of contour 9. Specifications for waxing the framework components for gold, chromium-cobalt, or titanium alloy castings must be furnished for the technician and are an integral part of the work authorization form Specifications that are adequate for most removable partial denture frameworks may be listed. This feature alone saves time and effort in preparing the work authorization and serves as a handy reference for the laboratory technician. The listing of average specifications does not preclude altering a specification when the situation necessitates other characteristics in a given component 10. The specific instructions provided in a work authorization must be so constructed that they will be a constant source of direction and supervision for the laboratory phases of a removable partial denture service. It is foolish to use undercut dimensions of 0.01 or 0.02 inch when a master cast is surveyed, unless written directions are included to incorporate these dimensions into the finished framework. 11. Work authorization blanks should be available in such a manner that a duplicate can be conveniently made and thus a copy can be supplied for both the dentist and the dental laboratory technician. The original may be a different color than the duplicate for ready identification. LEGAL ASPECTS OF WORK AUTHORIZATIONS ○ Made in duplicate ○ Retain a copy for a specified period from the date of work authorization ○ To substantiate or refuse claims and counterclaims that concern the illegal practice of dentistry ○ To aid in the settlement of misunderstandings between a dentist and the lab technician  DELINEATION OF RESPONSIBILITIES BY WORK AUTHORIZATION 1. The dentist is responsible for all phases of a removable partial denture service 2. Laboratory technician is responsible only to the dentist 3. A good dental laboratory technician is a valuable team member 4. The degree and quality of the team effort are the responsibility of the dentist 5. Depend on the dentist’s knowledge, experience, technical skill, administrative ability, integrity and ability to communicate effectively REFERENCES: Carr, A. B., McGivney, G. P., & Brown, D. T. (2015). McCracken’s Removable partial prosthodontics. Doc Aly. (2021, April 27). Removable partial denture Designing- work authorization [Video]. YouTube. GROUP 3: WAX PATTERN WITH WORK - Adheres firmly to investment model and burns out - The high transparency of the wax makes for optimal clarity of the AUTHORIZATION construction markings on the master model and saves unnecessary, time-consuming corrections to the wax-up WHAT IS A WAX PATTERN? Availability: In form of sheets A wax pattern in Removable Partial Denture (RPD) fabrication is a precise Color: Green model of the denture framework created using wax. It represents the design of Length: 17.5cm the final metal framework, including components like the major connector, Width: 8cm minor connectors, rests, and clasps. The wax pattern is carefully carved and Thickness: 0.25mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm shaped on a cast of the patient’s mouth, based on the approved design. 2. Stippled casting wax Purpose: The wax pattern helps in shaping the metal framework of the denture, allowing the dentist or dental technician to visualize how the - Wax for modeling the bases of upper partial dentures final prosthesis will fit and function. - Can be easily adapted and adheres firmly to the investment model with Process: Once the wax pattern is made (usually after designing the partial no additional wax adhesive denture and taking impressions), it is then invested in a mold material Textures: fine, medium, coarse (like gypsum). The wax is melted out, and the remaining mold is filled with metal, which solidifies to form the actual denture framework. - Allows customization on the surface shape as required by practitioner - The individual stippling of the cast partial denture base facilitates the WHAT ARE THE DIFFERENT WAX USED IN WAX gripping of food and reduces the foreign body sensation for the patient’s PATTERN? AND WHAT ARE THEIR USES? tongue Commercial wax and plastic patterns are available in a wide variety of - Availability: in form sheets shapes and gauges (thickness). - Color: green Preformed plastic patterns made of soft plastic material; they tend to - Length: 15cm stretch on removal from their backing. Therefore, care must be exercised - Width: 7.5cm when one is removing patterns. - Thickness: 0.35mm, 0.4mm, 0.5mm, 0.6mm Their use generally requires that tacky fluid be applied first to the investment cast at their area of placement. For clasps, for minor 3. Wax profile assortment connectors connecting to teeth, or for distal extension bases, bars, mesh, - Wax profiles are very easy to mold, do not bend up and can be easily and palatal coverage. fixed to the investment model 1. Smooth casting wax - The wax formula is designed to provide high internal stability and thus offers remarkable protection against inadvertent deformation and - Used for making patterns of maxillary major connectors constriction during shaping  - Half-teardrop: easy to finish and polish Availability Anatomical wax bar profile ○ Color: green Availability ○ Length: 17cm, 1.8 x 4.2mm - Small wax bar profile - Color: green ○ Color: green - Length: 17cm ○ Length: 17cm, 1.6 x 4.0mm - Consists of: Standard wax bar profile ○ 0.8mm beading wire ○ Color: green ○ 1.35mm sprues ○ Length: 17cm, 2.0 x 4.0mm ○ 2.0 x 4.0mm bars (for lower jaw) ○ 2.0 x 6.5mm casting strips (for upper jaw) 6. Wax retention for lower jaw partial denture frames ○ 1.15 x 1.75mm clasps, continuous ○ 2.0 x 4.5mm casting strips (upper, small bases) - For the secure attachment of plastic saddles to lower ○ 2.0 x 6.5mm casting strips (upper) partial dentures Availability: wax hole retentions and wax retentions 4. Wax border strips with retention with round holes ○ Color: red - Wax edge strips with retention considerably reduce the modeling time ○ Length: 17cm for the bases of maxillary partial dentures - The prefabricated shapes can be easily adapted to meet individual 7. Wax grid retention for maxillary partial denture frames requirements - Large wax grid retention: permit simple and effective shaping of Advantage: the border strip can easily be shaped as desired since the size can be retentions to total or partial dentures. They guarantee a high level of varied by trimming the tips of the retention security in the connection between the resin and the partial denture plate. Availability - Size: 60 x 42 mm Color: red - Wax diagonal grid retention: for shaping the retention for partial - Length: 17cm dentures. This particularly advantageous shape offers a very high degree of security in the connection between the resin and dentures 5. Anatomical wax bar profiles for lower partial denture frame - Size: 75 x 150 mm - Wax grid retentions with holes: can be used as retentions for partial - Three different wax: half-teardrop shape, rounded upper edge shape, maxillary dentures and as a reinforcement for acrylic full maxillary and concave shape acrylic dentures  - Size: 70 x 70 mm 3. Must not interfere with occlusion 4. Position lingual to internal lines approximately 1-1.5mm 8. Wax clasp profiles d) Major connector 1. Apply stipple sheet - Wax clasp profiles for the premolars or molars ensure a firm grip as well a. apply tacky fluid to refractory cast in the major as giving the partial denture the necessary stability connector area - The half-teardrop cross sections have proved to be very effective in a. adapt stipple sheet preventing food residues from becoming lodged b. trim excess - Wax profiles are very easy to mold, do not bend up and can be easily and c. seal in place with inlay wax securely fixed on the investment model with an optimum degree of e) Lingual Plating adhesion 1. Freehand method of wax-up - Wax clasp profiles help save time during modeling. 2. No more than 1mm thick a. blend inlay wax into stipple sheet Availability: b. tops of lingual plating should blend into the teeth Color: green without a step Molar clasp c. wax lingual plating following the design line Premolar clasp f) Denture base retention Straight ring clasp 1. Outer borders Curved ring clasp a. Apply tacky fluid to the flat side Bonyhard clasp b. Seal outer border to the tissue stop 2. Cross struts PROCEDURES FOR MAXILLARY WAX UP a. 12-gauge ½ round wax used for cross struts b. Follow design on the cast a) Transfer design from the master cast to the refractory cast c. Connects struts to the outer border 1. Do not etch the cast with the pencil tip d. Flame lightly 2. Do not transfer tripod marks or survey lines g) Clasps b) Preparatory wax-up 1. Use appropriate plastic clasp forms 1. Fill in bead line 2 2. Apply tacky fluid to clasps 2. Flow wax on crest of rugae 3. Cut shoulder of clasp at a 45 degree angle 3. Flow wax along relief pad adjacent to major connector (internal 4. Seal shoulder of clasp with a small amount of wax finish line) 5. Tack clasp tip carefully with a small amount of wax 4. Fill tissue stop with wax even with relief. h) Rest and minor connectors c) Finish lines 1. Use freehand method of waxing 1. Use 18 gauge round wax for all finish lines 2. Fill in rests completely 2. Placement should not interfere with positioning of denture 3. Occlusal rest should be slightly teeth  4. Minor connector should be approximately 1mm thick or as 2. Fill in rests completely thick as shoulder of clasp 3. Minor connector should be approximately 1mm thick or as 5. Junction of minor connector and rest should form a 90 degree thick as shoulder of clasp angle g) Finish lines i) Check rpd wax-up 1. Use 18-gauge round wax for all finish lines 1. Be sure all components have been waxed 2. Placement should not interfere with positioning of denture 2. Lightly flame if needed teeth 3. Position lingual to internal lines approximately 1 - 1.5 mm - if PROCEDURES FOR MANDIBULAR WAX UP external finish line is placed directly over the internal finish line, it will cause weak junction between the retention grid and the a) Transfer design from the master cast to the refractory casts same major connector as Max. 4. Finish lines should be sharp and smooth 1. Do not etch the cast with the pencil tip 5. Distal extension terminate at tip fishtail 2. Do not transfer tripod marks or survey lines h) Check RPD wax-up b) Preparatory wax-up 1. Be sure all components have been waxed 1. Internal finish line 2. Lightly flame if needed 2. Tissue stop 3. Hand articulate to check centric occlusion c) Major connector 1. 6-gauge ½ pear pattern 2. Apply tacky fluid to the plastic pattern WORK AUTHORIZATION 3. Bottom edge of plastic pattern is adapted right on design line 4. Cut ends of major connector at 45 degree angle I. DEFINITION 5. Seal plastic pattern with inlay wax all around a written document that provides instructions from a dentist to a dental lab d) Denture base retention technician for laboratory procedures 1. Mesh attached to plastic pattern The responsibility of a dentist to the public and to the dental profession to 2. Use 12-gauge ½ round safeguard the quality of prosthodontic services is controlled in part through e) Clasps meaningful work authorizations. 1. Use appropriate plastic clasp forms If work authorizations are properly completed, they provide a means for 2. Apply tacky fluid to clasps - do not excess tacky fluid as it can increased professional quality assurance and satisfaction in a removable create fins on the casting partial denture service 3. Clasp tip is positioned in the ledge and is curved up to the rest 4. Cut shoulder of clasp at a 45 degree angle 5. Seal shoulder of clasp with a small amount of wax 6. Tack clasp tip carefully with a small amount of wax f ) Rest and Minor Connectors 1. Use freehand method of waxing II. PARTS Additionally, another work authorization is 1. Name and address of the dental laboratory provided with a master cast that features an 2. Name and address of the dentist who outline for a removable partial denture initiates the work authorization framework. This form is straightforward 3. Identification of the patient and efficient, supplying the detailed 4. Date of work authorization information required for accurate 5. Desired completion date of the request processing of the request. 6. Specific instructions 7. Signature of the dentist The occlusal view of the cast clearly shows the denture outline, height of 8. Registered license number of the dentist contour, positions of retentive clasp undercuts, and locations of guide planes and rests. This clarity is crucial for the laboratory to fabricate the prosthetic exactly as intended, thereby enhancing communication and III. EXAMPLES improving workflow efficiency. IV. DEFINITIVE INSTRUCTIONS Only a minimum of writing is necessary Contain printed listings of materials and specifications The choice of metal for the framework Tooth selection A demonstration of respect for the laboratory technician ("Please", "Thank you") Not only ensures clarity but also simplifies correct execution Diagrams This work authorization as shown in the Color-code index accompanying image is designed to reduce the amount of writing needed while still offering LEGAL ASPECTS OF WORK AUTHORIZATION detailed instructions. It includes printed lists of materials and specifications, enabling users to Retain a copy for a specified period from the date of work authorize their use by simply checking boxes or authorization. filling in specific details. This format not only To substantiate or refute claims and counterclaims that concern the simplifies the process but also ensures that all illegal practice of Dentistry. essential information is clearly conveyed for To aid in the settlement of misunderstandings between a dentist and a efficient approval. dental laboratory technician.  DELINEATION OF RESPONSIBILITIES BY WORK arr, A. B., & Brown, D. T. (2015). McCracken’s removable partial prosthodontics. AUTHORIZATIONS Elsevier Health Sciences.arr, A. B., & Brown, D. T. (2015). McCracken’s removable partial prosthodontics. Elsevier Health Sciences. The dentist is responsible for all phases of a removable partial denture service. Laboratory technician is responsible only to the dentist. A good dental laboratory technician is a valuable team member. The degree and quality of the team effort are the responsibility of the dentist. Depend on the dentist’s knowledge, experience, technical skill, administrative ability, integrity and ability to communicate effectively. FAINA, JESSE VALENZUELA, ROAN PATRIK CASIGNIA, SOPHIA GUINEVERE LECAROS, KRYSTAL GAYLE DE PERIO, ELINN BELLE UNTALAN MANGILINAN, MAXEME TRACY URQUIOLA, KATRINA PALACIO CDA2 References: Carr, A. B., & Brown, D. T. (2015b). McCracken’s removable partial prosthodontics. Elsevier Health Sciences. http://removpros.dentistry.dal.ca/ewExternalFiles/RPD%20Manual%2011.pd f https://www.youtube.com/watch?v=hJRpgN83Xac Carr, A. B., & Brown, D. T. (2015b). McCracken’s removable partial prosthodontics. Elsevier Health Sciences. Mounting of Master Casts, Selection of Pontics and Setting I. Mounting - It is the laboratory procedure of attaching the maxillary or mandibular cast to an articulator. A. Purpose of Mounting - The purpose of mounting a master cast is to replicate the spatial orientation of a patient’s dental arch and occlusion within an articulator. B. Significance of Mounting 1. To maintain the vertical dimension of occlusion. 2. To keep horizontal centric jaw relation. 3. To ease arrangement of artificial teeth. C. Procedure of Mounting the Master Cast Most commonly used methods: 1. Assessment of cast-to-record adaptation when the articulator is closed in a terminal hinge position a. The articulator is placed in its terminal position. b. The condylar elements may be locked into this terminal position using some form of governing device. c. A jaw relation record is placed on one cast and the articulator is gently closed. d. During closure, the relationships between the occlusal surfaces and jaw relation record should be observed. e. The occlusal surfaces should follow an acute pathway into the record and should display excellent adaptation to the record. f. Should not apply pressure to the articulator to avoid distorting the record and to avoid having inaccurate result 2. Examination of the relationships between the condylar elements and codylar housings when the mounted casts are properly sealed in a jaw relation record a. The condylar elements are unlocked and permitted to move freely within their condylar housings. b. A jaw relation is placed on a cast and the remaining cast is gently settled into this record. c. Each condylar element should be located in its terminal position. d. Should not apply pressure to the articulator or casts. II. Selection and Setting of Pontics Teeth selection The process of selecting teeth for removable partial dentures (RPDs) closely parallels the selection process for complete dentures, as the replacement teeth must be functional, aesthetic, and compatible with the patient’s oral structures. Two main categories: - Anterior teeth selection  - Posterior teeth selection Purpose of teeth selection - To restore functionality (speech, mastication) - Maintaining vertical dimensions - Must blend seamlessly and be in alignment with the surrounding oral tissues Anterior Teeth Selection Anterior teeth play a crucial role in enhancing the aesthetics of a patient due to their prominence in the smile and their contribution to the overall facial appearance. Factors to consider in selecting Anterior teeth: - Size - Form/ shape - Shade - Type of material used Size of Anterior Teeth The size of the teeth should correspond to the proportions of the patient’s face and their gender. The following methods serve as guidelines for selecting the appropriate tooth size: - Methods using pre-extraction records Photographs - Helps determine the placement of teeth, arch form Study Casts- Reliable guide in selecting size and form and positioning of natural teeth Intraoral Radiographs- Can supply information about the length, width and shape of the teeth - Methods using anthropological measurements of the patient - Methods using anatomical landmarks Form of the Anterior Teeth The form or outline of the anterior teeth can be determined using the following factors: - Shape of the patient’s face or facial form- outline of the form or shape of the anterior teeth should harmonize with patient’s face Types of Facial forms: Square: Broader and flatter facial contours; often associated with wider, more angular anterior teeth. Ovoid: Rounded and softer facial contours; harmonizes with teeth that have gentle, curved outlines. Tapering: Narrow and angular facial features; matched with slender and pointed anterior teeth. Patient’s Profile - The patient’s facial profile (convex, straight, or concave) provides a guide for the labial contour (front surface curvature) of the anterior teeth. This principle is based on the idea that the shape and orientation of the anterior teeth should harmonize with the patient’s overall facial aesthetics, ensuring a natural and pleasing appearance. Dentogenic Concept and Dynasthetics: (Sex, Personality, Age or SPA factor) 1. Sex - The form or shape of the teeth differs in males and females. - In females, the incisal angles are more rounded and the teeth have a lesser angulation. In males, the incisal angles are rounded to a lesser degree and the teeth are more angular. - The incisal edge of the central incisors is parallel to the lips and the laterals are above the occlusal plane in males. But the incisal edges of the central and lateral incisors follow the curve of the lower lip in females. - The distal surface of the centrals are rotated posteriorly for females. - The mesial surface of the lateral incisors are rotated anteriorly in relation to the centrals in females. - In males the mesial end of the laterals are hidden by the centrals. This makes the canine very prominent in males. - Only the mesial thirds of the canines are visible in females because they are rotated anteriorly, whereas even the middle two-thirds of the canines are visible in males. - The cervical regions are prominent in males than in females. - Females on smiling expose more anterior teeth hence, the premolars should be arranged based on aesthetics for females 2. Age - The age of the patient is important in teeth selection because of the physiological and functional changes that occur in the oral tissues. The patient can be either young, middle-aged or old-aged. - Young: Teeth are longer, with rounded contours, bright white color, and high translucency. - Middle-Aged: Teeth exhibit moderate wear with slightly flattened edges, less translucency, and gradual darkening. - Old: Teeth are shorter, with flattened incisal edges, smooth surfaces due to wear, and noticeable yellow or gray discoloration from dentin exposure. - 3. Personality - the shape, size, arrangement, and overall appearance of these teeth can reflect or complement the patient’s personality traits. - Vigorous look can be given by:  - Selecting wider central incisors - Sharp line and points angles - Delicate personality: - Rounded contours - Smaller, narrower anterior teeth with softer curves. Color of the anterior teeth A single color can be described under the following parameters: Hues Saturation or chroma Brilliance or value Translucency Hue- Refers to the dominant color family (such as red, blue, green, etc.). Hues represent the basic color family without considering its lightness, darkness, tint, shade and intensity. Saturation or chroma- refers to the intensity or purity of a color. A highly saturated color is vivid and intense, while a less saturated color appears more washed-out or grayish. Chroma is closely related to saturation, often describing the strength of a color's hue. Brilliance or value- indicates the lightness or darkness of a color. It is determined by the amount of white or black mixed with the color. A high-value color is lighter (closer to white), while a low-value color is darker (closer to black). Translucency- Refers to the ability of a material or color to transmit light partially. A translucent object allows some light to pass through, but not enough to clearly see through it. In terms of color, it implies a semi-transparent quality where the underlying layer or surface can be slightly visible. The hue and brilliance of a tooth is influenced by the following factors: Age: - Hue: As people age, the enamel on their teeth naturally thins, and the underlying dentin (which has a yellowish or grayish tone) becomes more visible. This can give the teeth a slightly warmer or yellower hue, especially in older adults. - Brilliance (Value): Teeth tend to lose their brilliance or value (brightness) as we age. Enamel thins, and staining from food, beverages, and smoking can accumulate, leading to a duller, darker appearance of the teeth. Habit: - Hue: Habits like smoking, drinking coffee, tea, or red wine, or eating foods with strong pigments can cause staining of the teeth. Over time, these stains can change the hue of the  teeth, making them appear more yellow, brown, or even gray, depending on the substance involved. - Brilliance (Value): Poor oral hygiene or a lack of professional dental cleanings can reduce the brilliance of teeth. Stains and plaque buildup can make teeth appear dull and less bright. Conversely, habits like regular brushing, whitening treatments, or good oral care can help maintain or restore a brighter, more vibrant tooth appearance. Complexion: - The depth of complexion can also influence how bright or brilliant teeth appear. A darker skin tone often makes white teeth appear brighter due to contrast, while fairer skin may make the teeth look less striking if they are too white. Color of the eyes: - There are eye colors that are warm and cold, both having their own undertones. The coolness or warmth in eye color can guide a dentist toward choosing a tooth shade that either matches or contrasts with their eye color for a more balanced overall look. Color of the hair: - Darker hair often creates a contrast that makes teeth appear whiter and more brilliant, especially if the person has lighter or whiter teeth. Light hair tends to blend more with lighter teeth, so a slightly more pronounced whiteness may be needed to stand out. The following reference points on the face can be used to select the color of the tooth: Side of the nose. Under the lips with only the incisal edge exposed. Under the lips with the mouth wide open and only the cervical. Squint test: - it is a method used to check and compare the color of the teeth with the color of face. Selection of the Type (Material) of Anterior Teeth - Acrylic denture teeth Indications: - most anterior space - When the labial contour must be built with a flange Advantages:  - Aesthetically acceptable - It is not brittle even on the thin section - Can withstand deep bite cases Disadvantages: - The Labial surface wears excessively leading to compromised aesthetics. Porcelain denture teeth Indications: - For most anterior spaces if there enough space to fit it - If the labial contour is to be restores with flange extension Advantages: - Excellent aesthetic Disadvantages: - Brittle Interchangeable facing: Indications: - For deep bite cases - For single tooth replacements Advantages: - Strongest of all artificial teeth - Facing can be replaced easily when fractured Disadvantages: - Not good for aesthetic like porcelain or acrylic denture teeth The pressed-on or post tooth Indication: - Similar to interchangeable facing generally Advantages: - For its small size, it is very strong Disadvantages - Only fair to moderate aesthetics Arranging of Artificial Teeth Guidelines for Setting Anterior Teeth: Replace Acrylic Resin Record Base: Attach the baseplate wax to the framework and place it on the cast. Start with the Central Incisor: If teeth are missing across the midline, begin by positioning the central incisor. Reshape Ridge Lap: Adjust the ridge lap portion of the artificial tooth to ensure it fits without shortening the clinical crown length excessively. Place Teeth in Original Position: Set the teeth as close as possible to the original position of the natural teeth. Recontour Proximal Surfaces: Adjust the proximal surfaces of the artificial teeth to ensure proper contact. Denture Base Flange Contouring: Carefully smooth and contour the denture base flanges to ensure proper lip support and esthetics. Guidelines for Setting Posterior Teeth: Align teeth along the residual ridge for stability. Follow the curve of Spee and curve of Wilson to maintain occlusal balance. Ensure proper occlusion: Class I (Bilateral Distal Extension): Ensure both working and non working side contacts occur simultaneously during function. Class II (Unilateral Distal Extension): Establish working-side contacts only during function. Class III (Tooth-Supported RPD): Maintain canine-protected occlusion.  Class IV (Anterior Tooth Replacement): Provide no or light contact with opposing natural teeth in centric occlusion. Maximize support from the denture base for chewing stability. Check and adjust functional contacts using articulating paper. Ensure positioning minimizes dislodging forces and maintains stability. Festooning Festooning is the process of carving the denture base to replicate the natural gingival contours, enhancing esthetics and functional retention. Objectives: Restore natural gingival contours. Enhance denture retention and esthetics. Support soft tissue function. Two Methods of Festooning 1. Press-On Method: This technique involves pressing the denture base onto the cast to form the gingival contours. The pressure creates natural tissue-like contours, allowing for a more realistic fit and shape. 2. Drop-On Method: In this method, the material is “dropped” onto the cast and gradually built up to form the gingival contour. This allows for a smoother, more gradual shaping of the tissue area. Guideline for Festooning Accurate Duplication of Soft Tissues: Shape the denture base to replicate the gingival and mucosal contours around abutments and retainers for proper fit and esthetics. Labial and Buccal Fullness: Provide adequate fullness to support the lips and cheeks, for functional stability and esthetics. Notches for Mucosal Attachment: Create notches to accommodate mucous membrane attachment in both size and direction, ensuring retention and comfort. Compatibility with Lip and Cheek Shape: Contour denture flanges to match the shape of the lips and cheeks, for both esthetics and functional support. Minimal Bulk in Lingual Flange: Ensure minimal bulk in the lingual flange of mandibular dentures, except at the borders, to avoid interference with tongue movement and ensure comfort. Avoiding Interference with Framework: Ensure the festooned denture contours do not interfere with the framework components (clasps, rests, and connectors), for functionality. Polishing: Polish the denture base to a smooth, natural finish, for improved patient comfort and esthetics. Border Seal: The border seal is the critical process that ensures intimate contact between the denture base and the soft tissue to optimize retention and prevent movement during function. ○ Done after finishing the festooning of all polished surfaces ○ Care must be taken in that to ensure not to leave any space between base and cast. TRY-IN OF WAXED DENTURES I. FIRST TRY-IN: TRY-IN THE METAL FRAMEWORK STEPS: 1. Inspect the framework of the master cast - Inspect for bubbles and other defects on the intaglio surface - Check for abraded areas on the master cast, check for polished and unpolished areas - Check for adequate thickness 2. Check the framework on the master cast - Verify the design of the framework with the laboratory prescription or diagnostic cast - Inspect the rests - Rests should not be overcontoured and undercontoured - Examine the relationship between the framework and the soft tissue areas - Check for proper adaptation and placement of clasps - Check the ease of framework removal 3. Check the framework in the mouth - Scenario: If the framework fits the cast but does not fit in the mouth, it is likely the cast is not accurate reproduction of the mouth 4. Fit the framework to the abutment teeth - Check for rocking of the framework in both anteroposterior and buccolingual directions - Check for close adaptation of rests, clasp arms, and lingual plates - Check for physiologic relief on distal extension frameworks - Check retention - Check soft tissue contact or relief Occlude Disclosing Fit Checker “aerosol Wax spray” two three three dimensional dimensional dimensional indicating indicating adjustment medium medium with silicone  indicating medium Advantages: Advantages: Advantages: - Thin and - Sets - Minimal accurate immediat distortion - ely Not - Inexpensi easily ve displa - ced Show - Can s how dissol far ve in from saliva seatin g Disadvantage Disadvantage Disadvantage s: s: s: - Difficult - Can stick - More to remove to teeth expen - Can’t - Can be sive, tell distorted cost how - Sets far relativ from ely seatin slowly g (~1- 2min) - Can tear or pull of the frame work 5. Adjusting the framework to the opposing occlusion - Identify natural tooth contacts in the centric occlusion or maximum intercuspation positions - Adjust the framework in the CO/MIP position - Adjust the framework during eccentric movements PHASES OF FIT ADJUSTMENT FOR METAL FRAMEWORK 1. Fit Adjustment a. Disclosing wax:  A little piece of wax is taken on a spatula and spread over the intaglio of the framework. After seating, areas of premature contact will wipe away the wax, creating a "show through". This is an area that can be removed with a bur. Process is repeated until there is no "show through" seen. b. Occlude “aerosol spray” - Used when there is incomplete seating of the framework Occlude is sprayed on the intaglio of the RPD. After seating, areas of premature contact will wipe away the wax, creating a "show through". Similar to disclosing wax, show through is detected if  there is premature contact. Metal is reduced in the area of show through. 2. Clasp Adjustment - Plier options: a. THREE PRONG PLIER: bends a flat wire b. BIRD BEAK PLIER: flatten a bent wire - Bending cast clasps is risky as they have a flat area. This flat area is usually towards the abutment tooth - Any adjustment should be done perpendicular to the flat plane and not parallel to the plane as it predisposes the clasp to fracture. - On the other hand, wrought wire clasp can be bent in any direction. - It has a toughness exceeding that of a cast clasp. - Bend in a vertical or horizontal manner.  Bending clasps to achieve better retention should always be done by bending the clasps into a deeper undercut not just by making the clasps tighter into the tooth. 3. Occlusion Adjustment Shimstock is used to confirm that the occlusion with and with a partial in place is identical. If occlusion are not identical, areas of premature contacts are marked and adjusted with a bur. II. BITE REGISTRATION Bite registration is a critical step in the fabrication of removable partial dentures (RPDs) because it ensures the accurate articulation of the dental arches and the appropriate positioning of the occlusal surfaces. Objectives of Bite Registration 1. Accurate Recording of Jaw Relations: To capture the correct centric relation (CR) or centric occlusion (CO) to avoid occlusal disharmony. 2. Preservation of Vertical Dimension of Occlusion (VDO): Ensures the proper vertical relationship between maxilla and mandible. 3. Stable Occlusal Contacts: To ensure balanced occlusion and minimize lateral forces on the prosthesis. 4. Functionality and Esthetics: Ensures the prosthesis does not interfere with speech, mastication, or esthetic appearance. Key Concepts to Bite Registration  1. Classification of Partially Edentulous Arches ○ Kennedy Class I and II: Distal extension cases, where special attention is needed to record the functional position of the edentulous areas. ○ Kennedy Class III and IV: Tooth-supported RPDs, where jaw relations are often recorded using the natural teeth as a guide. 2. Types of Jaw Relations to Record ○ Centric Relation (CR): A reproducible, repeatable position often used when no posterior teeth are present. ○ Centric Occlusion (CO): The position where the teeth make the maximal contact in habitual occlusion. Often used if sufficient natural teeth remain. Materials Used for Bite Registration Wax Rims: Baseplate wax rims are built on record bases to mimic the missing occlusal surfaces. Zinc Oxide-Eugenol (ZOE) Paste: Provides detailed, accurate impressions of the occlusal relationship. Polyvinyl Siloxane (PVS) Materials: Highly accurate, easy to handle, and provide consistent results. Aluwax or Impression Compounds: Used for recording functional occlusion in distal-extension RPDs. Steps in Bite Registration 1. Fabrication of Record Bases and Occlusal Rims: Custom-made record bases ensure a stable platform for the wax rims. Occlusal rims are adjusted to establish the appropriate VDO. 2. Adjustment of Occlusal Rims: Measure facial landmarks (e.g., inter-pupillary line, Camper’s plane) to achieve correct alignment. Adjust height to achieve correct VDO. 3. Recording Centric Relation: Guide the mandible into centric relation using bimanual manipulation or chin-point guidance. Ensure the patient does not shift into habitual occlusion prematurely. 4. Verification of Records: Check for symmetry, VDO accuracy, and midline alignment. Verify using phonetics (e.g., "S" sounds) and esthetic considerations. Special Considerations for Distal Extension RPDs In Class I and II cases, functional bite registrations are essential: Use physiologic method by allowing soft tissue compression to mimic functional loading. Use adjusted wax rims under functional loads or selective pressure techniques. Errors to Avoid in Bite Registration  1. Instability of Record Bases: Ensure well-fitting record bases to prevent movement during registration. 2. Incorrect VDO: Avoid over- or under-extending the occlusal rims. 3. Premature Tooth Contact: Ensure no premature contacts or interferences are recorded. 4. Patient Movement: Ensure the patient is relaxed and cooperative during registration. III. Mounting Master casts, and in some cases the refractory casts as well, are mounted in the articulator in order that proper occlusions may be established on the partial denture prosthesis, and it is important that this be done at the proper stage in the over-all construction procedures. When can the master cast be mounted? The master casts may be mounted in the articulator after the metal framework is made, either cast or assembled, in those cases (1) where the opposite jaw is being supplied with a complete artificial denture which is being made at the same time or later or (2) where the establishment of a desirable occlusion on the metal framework, by grinding in the mouth, would be a simple procedure. For cases presenting extensive edentulous areas, such as free-end extension designs, the making of jaw relation records is greatly simplified, and the records are more likely to be accurate when the metal framework is completed previous to the making of jaw relation records and the mounting of the master casts in the articulator. Most commonly used methods include: 1. Assessment of cast-to-record adaptation when the articulator is closed in a terminal hinge position 2. Examination of the relationships between the condylar elements and condylar housings when the mounted casts are properly seated in a jaw relation record First Method: 1. The articulator is placed in its terminal position 2. The condylar elements may be locked into this terminal position using some form of governing device 3. A jaw relation record is placed on one cast and the articulator is gently closed 4. During closure, the relationships between the occlusal surfaces and jaw relation record should be observed by the practitioner 5. The occlusal surfaces should follow an acute pathway into the record and should display excellent adaptation to the record 6. Should not apply pressure to the articulator to avoid distorting the record and to avoid having inaccurate result Second Method:  1. The condylar elements are unlocked and permitted to move freely within the their condylar housings 2. A jaw relation is placed on a cast and the remaining cast is gently settled into this record ○ If the casts cannot be accurately positioned in the record, an inaccuracy exists, and the practitioner must determine the source of this inaccuracy. ○ If the casts can be accurately positioned in the record, the practitioner must assess the relationship between the condylar elements and the condylar housings. 3. Each condylar elements should be located in its terminal position 4. Should not apply pressure to the articulator or casts Remember: If the original mounting is verified as correct, the practitioner may proceed. If the accuracy of the original mounting cannot be verified, another jaw relation record should be made and the mounting should be reevaluated. If this record fails to verify the original mounting, the practitioner should suspect an inaccuracy in the mounting and should remount the mandibular cast (the verification process should then be repeated.) Completion of the prosthesis should not be considered until the practitioner has verified the accuracy of the mounting. IV. Fabricate the Occlusion Rims MATERIALS: 1. Hard Baseplate Wax Use of a wax occlusal rim can be inaccurate when the occlusal portion of the rim is mishandled. When some soft material that sets to a rigid state, such as impression plaster or bite registration paste, is used in conjunction with wax rims to record static occlusal relations, many of the errors common to wax rims are eliminated ○ provided some space for the material exists between the occlusion rims, the opposing teeth, or both, at the desired vertical dimension to be recorded. Registration made on wax occlusion rims with the use of a wax registration material must be handled carefully and mounted immediately. 2. Modeling plastic (compound) It has several advantages and may be used rather than wax for occlusion rims.  It may be softened uniformly by flaming, yet when chilled it becomes rigid and sufficiently accurate. It may be trimmed with a sharp knife to expose the tips of the opposing cusps to recheck or position an opposing cast into the record rim. Because of its greater stability, modeling plastic is preferable for this purpose when the edentulous situation permits the use of flat plane tracings. ○ An example of such a situation occurs when an opposing complete denture is made concurrently with the removable partial denture OCCLUSION RIMS: Occlusion rims made of extra hard baseplate wax or modeling plastic may be used to support intraoral central bearing devices, intraoral tracing devices, or both. ○ Occlusion rims for static jaw relation records should be so shaped- that they represent the lost teeth and their supporting structures - An occlusion rim that is too broad and is extended beyond where prosthetic teeth will be located is inexcusable. ○ Such rims will substantially alter the shape of the palatal vault and the arch form of the mandibular arch, will crowd the patient’s tongue, will have an unwelcome effect on the patient, and will offer more resistance to jaw relation recording media than will a correctly shaped occlusion rim. Occlusion rims for recording functional, or dynamic, occlusion must be made of a hard wax that can be carved by the opposing dentition. FABRICATION: 1. A softer wax may be used than is required for the recording of occlusal paths over 24 hours or longer. Hard inlay wax seems to satisfy the requirements for a wax that is durable yet capable of recording a functional occlusal pattern. This wax is packaged in the form of sticks. 2. A layer of hard, sticky wax is first flowed onto the surface of the denture base. Two sticks of the inlay wax are then laid parallel along the longitudinal center of the denture base and are secured to it with a hot spatula. This is the only preparation needed before the dental appointment. Because neither the height nor the width of the occlusion rim can be known in advance, and because deep warming of a chilled wax rim is difficult, the rim is not completed before the appointment. 3. With the patient in the chair, a hot spatula is inserted into the crevice between the two sticks of wax, making the center portion fluid between two supporting walls. Some transfer of heat to the supporting walls occurs, resulting uniform softening of the occlusion rims. 4. The patient is asked to close into this wax rim until the natural teeth are in contact; this establishes both the height and the width of the occlusion rim. Wax is added or carved away as indicated, and the patient is asked to make lateral excursions. Any excess wax is then removed, and any unsupported wax is supported by addition.  5. Finally, wax is added to increase the occlusal vertical dimension sufficiently to allow for (1) denture settling, (2) changes in jaw relations brought about by the reestablishment of posterior support, and (3) carving in all mandibular excursions. When sufficient height and width have been established to accommodate all excursive movements, the patient is given instructions for chewing in the functional record and is then dismissed. V. Selection and Setting of Pontics Selection and Setting of Pontics Functions of prosthetic teeth: Esthetics -restore the natural appearance of the patient’s smile. Phonetics - assist in the articulation of sounds for clear speech Masticatory efficiency - enable effective chewing, crucial for digestion and overall health. The occlusion developed with RPDs should be physiologically harmonious, allowing the supporting structures to remain in a good state of health with functional stress distributed among all the occluding teeth. Pontic Selection Selection of color and size of acrylic resin denture teeth - done after framework try-in It is recommended to use a shade guide of the actual teeth to be placed, as conversion guides from one shade guide to another can often be inaccurate. Consider the esthetic, functional, and structural requirements needed as well as the material to be used Note: Accurately mounted diagnostic casts provide useful information for selecting pontics and determining occlusal scheme to be used. Pontic Selection Materials used as pontics: porcelain, acrylic resin, composite resins Shade Selection By measuring the casts and selecting a shade from the patient's existing prosthesis or natural teeth, a suitable tooth can usually be selected. To ensure selection of appropriate shade, prosthesis should be viewed using a variety of light sources (natural, fluorescent and incandescent) – accurately matching the shade in different lighting conditions. Pontics Type of choice: manufactured teeth Common material of choice: acrylic resin *unless the opposing occlusion is porcelain » porcelain must be used as well to prevent the opposing dentition to abrade the RPD Pontics The arrangement of the anterior should harmonize with the abutment. The appearance may need to be modified, if incisal wear is present on the natural teeth should be simulated on the denture. Classification for Types of Posterior Teeth Classification for types of posterior teeth 1. Anatomic teeth ( 33° and 30° ) ○ Simulate the natural teeth form. ○ Have inclines of approximately 33 degree ○ Anatomic teeth with 30 degree cuspal-angulations are also available and are commonly known as Pilkington-Turner teeth ○ Indication: Normal opposing ridge relation & good ridge size. Young patients. 2. Semianatomic teeth ( 22°, 20°, 12° and 10° ) ○ also known as modified cusp or low-cusp teeth ○ They may have 20 or 10 degree cuspal angulation. ○ The 10 degree semi-anatomic teeth are commonly known as Anato-line teeth. ○ Look like well worn natural teeth ○ Indications: Mild ridge resorption. Mild discrepancies in jaw relation 3. Nonanatomic or cuspless teeth (monoplane, 0° ) ○ Are known as 0 degree, cuspless or monoplane teeth. ○ They have no cuspal angulation hence are very flexible to set ○ Indications: Crossbite tooth relationships. Poor muscular control Severely resorbed ridges Large discrepancy between centric jaw relation and centric occlusion Arranged in a plane and balanced only in plane 4. Special form ( °'s vary ) ○ These have variable cusp angles to suit specific needs. Occlusal Schemes and Pontic Selection Occlusal schemes refer to the arrangement and interaction of the upper and lower teeth when the jaws are closed and during movements like chewing. Different occlusal schemes can be chosen based on the clinical situation and the needs of the patient. Balanced Occlusion Centric Occlusion Lateral movement Non-Balanced Occlusion Lingualized Lingualized non-balanced Lingualized balanced Balanced Occlusion Characteristics: In balanced occlusion, the teeth are arranged so that there are simultaneous contacts on both sides of the mouth during both centric (when teeth are fully closed) and eccentric movements (side-to-side or front-to-back movements). Tooth Forms Used: Anatomic or semi anatomic teeth, or a combination of these with a compensating curve, which helps in achieving balance during movements. Indications: Balanced occlusion is indicated when most occlusal contacts on natural teeth are missing or when RPD opposes a complete denture, helping to stabilize the opposing complete denture. Non-Balanced Occlusion Characteristics: In non-balanced occlusion, the teeth do not have simultaneous contacts during eccentric movements. This is simpler to achieve and often used in certain clinical scenarios. Tooth Forms Used: Any form can be used, but non-anatomic or monoplane teeth are most common due to their simplicity. Indications: Non-balanced occlusion is indicated in cases where the occlusion is not required to maintain balance during eccentric movements, and a simpler occlusal scheme is preferred. Lingualized Occlusion Characteristics: Lingualized occlusion is a compromise between anatomic and nonanatomic schemes. The upper (maxillary) teeth have a more pronounced cusp  (anatomic or semi-anatomic), while the lower (mandibular) teeth are flatter (semi-anatomic or nonanatomic). This scheme aims to concentrate the occlusal forces on the lingual (tongue side) cusps of the upper teeth, providing more stability and less wear. Tooth Forms Used: Maxillary anatomic or semi-anatomic with mandibular semi-anatomic or nonanatomic teeth. Indications: Lingualized occlusion is indicated when canines are present and not periodontally compromised, and an anterior-guided (canine-protected) occlusion is preferred. SUMMARY: Pontic Selection According to Occlusal Scheme What teeth you should use to develop: Balanced occlusion ○ Anatomic, Semianatomic, combination of forms (semi anatomic and nonanatomic), all usually used with a compensating curve Non-balanced occlusion ○ Any tooth form ○ most common: non-anatomic or monoplane Lingualized occlusion ○ A combination maxillary anatomic and mandibular semi anatomic, or maxillary semi anatomic and mandibular nonanatomic Pontic selection: Occlusal Scheme Most occlusal contacts on natural teeth are missing — Balanced occlusion Canines are present and not periodontally compromised — Anterior-guided (canine-protected) occlusion RPD opposes a complete denture — Balanced (to help stabilize opposing CD)