Denture Base Considerations PDF

Denture Base Considerations Functions of Denture Bases in Control of Prosthesis Functions of Denture Bases in Control of Prosthesis Movement Methods of Atta...

Denture Base Considerations Functions of Denture Bases in Control of Prosthesis Functions of Denture Bases in Control of Prosthesis Movement Methods of Attaching Denture Bases Methods for Incorporating Dental Implants 1. Supports the artificial teeth and RPD support (mainly) Advantages of Metal Bases 2. Transfers functional forces to supporting oral Ideal Denture Base Material structures Methods of Attaching Artificial Teeth 3. Functional stability (distal extension) 4. Masticatory function Need for Relining 5. Esthetic Stress-Breakers (Stress Equalizers) 6. Stimulation of the underlying tissues of the residual ridge Tooth-Supported Partial Denture Base Function of denture base in anterior teeth Replacement: Occlusal forces are transferred directly to the (1) provide desirable esthetics abutments through rests. (2) support and retain the artificial teeth in such a way The denture base and the supplied teeth that they provide masticatory efficiency and assist in serve to prevent horizontal migration of all transferring occlusal forces directly to abutment teeth through rests; abutment teeth in the partially edentulous (3) prevent vertical and horizontal migration of arch and vertical migration of teeth in the remaining natural teeth opposing arch. (4) eliminate undesirable food traps (oral cleanliness) (5) stimulate the underlying tissues.  Distal Extension Partial Denture Base Retention of denture bases : Support is critical to the goal of minimizing functional movement and improving stability of the prosthesis. (1) Adhesion, which is the attraction of saliva to the Maximum support from the residual ridge by using broad, denture and tissues accurate denture bases, which spread the occlusal load equitably (2) Cohesion, which is the attraction of the molecules of over the entire area available for such support saliva to each other (3) atmospheric pressure Primary retention for the removable partial denture is (4) physiologic molding of the tissues around the accomplished mechanically by placing retaining elements on the polished surfaces of the denture abutment teeth. Secondary retention is provided by the intimate (5) the effects of gravity on the mandibular denture relationship of denture bases and major connectors (maxillary) with the underlying tissues Methods of Attaching Denture Bases METHODS FOR INCORPORATING DENTAL IMPLANTS Acrylic-resin bases are attached to the partial denture framework by means of a minor connector designed so that a space exists between the framework and the underlying tissues of the residual ridge Implants placed anteriorly, to enhance retention by removing the need for a visible clasp, must take into account retentive device bulk and connection requirements IDEAL DENTURE BASE MATERIAL Modifications required for implants placed more distal, for purposes of support 1. Accuracy of adaptation to the tissues 2. Dense, nonirritating surface capable of receiving and maintaining a good finish 3. Thermal conductivity 4. 4. Low specific gravity; lightweight in the mouth 5. 5. Sufficient strength; resistance to fracture or distortion 6. 6. Easily kept clean 7. 7. Esthetic acceptability 8. 8. Potential for future relining 9. 9. Low initial cost ADVANTAGES OF METAL BASES METHODS OF ATTACHING ARTIFICIAL TEETH 1.Porcelain or Acrylic-Resin Artificial Teeth Attached with Acrylic-Resin 2. Porcelain or Resin Tube Teeth and Facings Cemented Directly to Metal Bases 3. Resin Teeth Processed Directly to Metal Bases 4.Metal teeth 1. Accuracy and performance of form 5.Chemical bonding 2. Comparative Tissue Response 3. Thermal Conductivity 4. Weight and Bulk NEED FOR RELINING Loss of support for a distal extension base results in loss of occlusal contact between the prosthetically supplied teeth and the opposing dentition and a return to heavy occlusal contact between the remaining natural teeth. Usually this is an indication that relining is needed NEED FOR RELINING STRESS-BREAKERS (STRESS EQUALIZERS In distal extension situations, the use of a rigid connection between the denture base and supporting teeth must account for base movement without causing Second manifestation of change in the supporting ridge tooth or tissue damage. is evidence of rotation about the fulcrum line with the In such situations, stress on the abutment teeth and indirect retainers lifting from their seats as the distal residual ridge is minimized through the use of functional extension base is pressed against the ridge tissue basing, broad coverage, harmonious occlusion, and correct choice of direct retainers. Two major types of clasp assemblies are used for distal extensions because of their stress-breaking design. Example: Wrought wire clasp  Thank You Introduction Marketing Department Mon. Feb. 21. 2018 Introduction Introduction Dr :Mahmoud El Homossany Objective: 1-Indications and Contraindication of removable partial denture 2-Classification of Partial denture  Reference Chapter 1,3 TERMINOLOGY Prosthesis Is an artificial replacement of an absent part of the human body Dentulous Patients Patients having a complete set of natural teeth Edentulous Patients Patients having all their teeth missing Edentulous Patients Partially Edentulous Patients Patients having one or more but not their entire natural teeth missing. COMPLETE DENTURE Removable Partial Denture = R.P.D Fixed bridge= F.P.D Removable Partial Denture, R.P.D Fixed bridge Implant Implant  Removable Partial Denture (RPD) Free End Edentulous Area (Distal extension Removable edentulous area): An edentulous area, which has dental an abutment tooth on one side only prosthesis Bounded Edentulous Area: An edentulous area, (appliance) which has an abutment tooth on each end replacing one or more natural teeth and associated oral structures Abutment: A tooth, a portion of a tooth, or that portion of a dental implant that serves to support and/or retain prosthesis INDICATIONS FOR REMOVABLE PARTIAL DENTURES 1- No abutment tooth posterior to edentulous space (Free end edentulous area) INDICATIONS FOR REMOVABLE PARTIAL DENTURES INDICATIONS FOR REMOVABLE PARTIAL DENTURES 2- Long edentulous bounded span, too 3- Periodontally weak teeth not sufficiently sound extensive for fixed restoration to support fixed- partial denture.  Periodontally Free end edentulous area weak teeth Periodontally weak teeth 4- With excessive loss of residual bone, the use of labial flange or need to restore lost tissues. Excessive loss of residual bone With excessive loss of residual bone, space is seen under the pontic. INDICATIONS FOR REMOVABLE PARTIAL DENTURES 5- After recent extraction, usually done only to improve esthetics, or for patient satisfaction. 6- Need of bilateral bracing (cross arch stabilization) 7- Young age (less than Young Old 17 years). Young age (less than 17 years) has a high pulp horn 8-Economic considerations, attitude and desire of OBJECTIVES OF REMOVABLE PARTIAL DENTURES the patient. Preservation of the Remaining Tissues A- Preservation of the health of the remaining teeth. B- Prevention of muscles and TMJ Dysfunction. C-Preservation of the residual ridge. D- Preservation of the tongue contour and space. Consequences of Tooth Loss Need for Removable Partial Dentures Anatomic Physiologic Patient use of removable partial dentures has been In general, bone loss is We are replacing both high in the past and is expected to continue in the greater in the mandible the physical anatomic tools for mastication future. Some patients who are given the choice than in the maxilla and and the oral capacity more pronounced between a prosthesis entirely supported by for neuromuscular implants or a removable partial denture are not Posteriorly than functions to anteriorly, and it manipulate food. able to pursue implant care. This contributes to produces a broader higher use of removable partial dentures. mandibular arch while constricting the maxillary arch.  Migration of teeth into the edentulous area following the loss of the natural Replacement of lost teeth prevents the migration of teeth into the edentulous area following the loss of the natural dentition Change the pattern of mandibular closure as a result of loss of some teeth Normal masticatory cycle OBJECTIVES OF REMOVABLE PARTIAL DENTURES OBJECTIVES OF REMOVABLE PARTIAL DENTURES Restore the Continuity of the Dental Arch Improvement of Esthetics, and Providing Support to the Paraoral Muscles, Lips and to Improve Masticatory Function Cheeks  OBJECTIVES OF REMOVABLE PARTIAL DENTURES OBJECTIVES OF REMOVABLE PARTIAL DENTURES Enhance psychological comfort Restoration of Impaired speech *Restoration of anterior teeth improves and restores appearance *RPD should provide socially acceptable esthetics OBJECTIVES OF REMOVABLE PARTIAL DENTURES Possible disadvantages of a clasp-retained Restoration of Impaired speech partial 1. Strain on the abutment teeth often is caused by 3. Caries may develop improper tooth preparation beneath clasp or clasp design, and/or components, loss of tissue support under distal extension especially if the partial denture bases. patient fails to keep 2. Clasps can be un-esthetic, the prosthesis and the particularly when they are placed on visible tooth abutments clean. surfaces without consideration of esthetic impact. Tooth decay Ill fitting denture Inflammation, ulceration ,gingival recession, bone resorption Inflammatory changes of Sensitivity soft tissues from acryl HAZARDS OF IMPROPERLY DESIGNED PARTIAL DENTURES  ADVANTAGES OF REMOVABLE PARTIAL DENTURE OVER FIXED PARTIAL DENTURE CLASSIFICATION OF PARTIALLY EDENTULOUS ARCHES Classifications are important to facilitate communication 1- RPD constructed for any case whilst FPD between the dentist and the laboratory technician are confined to short spans bounded by healthy teeth and with a normal occlusion. Requirements of an Acceptable Classification: 2- Cheaper than fixed partial denture 1- Permit immediate visualization of the type of partially edentulous arch 3- They are more easily cleaned 2- Permit immediate differentiation 4- They are more easily repaired between bounded and free extension RPD. 5- No tooth reduction is required 3- It should be universally accepted CLASSIFICATION OF PARTIALLY EDENTULOUS ARCHES I- Classification According to the type of support of the R.P.D.: Tooth and Tissue Supported RPD 1-Tooth and Tissue Supported RPD (Tooth and tissue borne) 2- Tooth Supported RPD (Tooth-borne) removable partial denture 3-Tissue Supported RPD (Tissue borne) *Tissue Supported RPD Tooth Supported RPD CLASSIFICATION OF PARTIALLY EDENTULOUS ARCHES II- Classification According to the most posterior edentulous span or spans Class I: Bilateral edentulous areas located posterior to the Class I Class II remaining natural teeth. Class II: Unilateral edentulous area located posterior to the remaining natural teeth. Class III: Unilateral edentulous area with natural teeth, both anterior and posterior to it Class IV: Single, bilateral edentulous area located anterior to the remaining natural teeth. Class III Class IV  The numeric sequence of the classification system is based on the frequency of occurrence of each class. Class I being the most common while class IV is the least common. Kennedy's Class I mod.1 Class II mod.3 classification was then modified by Applegate Additional edentulous areas are referred to as modification spaces and are designated by their number Class III mod. 1 Class IV ???? Applegate's rules for applying Kennedy classification Rule1 Rule1 Classification should follow mouth preparations, since further extractions may alter the class X If the left molar is extracted class III becomes class II Applegate's rules for applying Kennedy Applegate's rules for applying classification Kennedy classification Rule2 Rule3 If the third molar is missing and not to be replaced, it is not considered in the If the third molar is present classification and to be used as an abutment, it is considered in the classification  Rule3 Applegate's rules for applying Kennedy classification Rule4 If the second molar is missing and not to be ???? replaced, because the opposing second molar is also missing, it is not considered in the classification ???? Applegate's rules for applying Kennedy Applegate's rules for applying Kennedy classification classification Rule5 Rule 6 Additional edentulous areas other The most posterior edentulous than those determining the class area (or areas) always are referred to as modification determines the classification spaces and are designated by their number Applegate's rules for applying Applegate's rules for applying Kennedy classification Kennedy classification Rule 8 Rule7 There can be no modification areas in The extent of the modification class IV arches, because if there is a is not considered, only the posterior edentulous area beside the anterior one, the former will determine number of additional edentulous the class and the anterior edentulous areas area will be a modification to the class ???????  The Component Parts of Removable Partial Dentures Denture Base Artificial Teeth Supporting Rests Connectors: Major Connectors Retainers Minor Connectors Direct retainers Indirect Retainers 3 1 2 5 4 Thank You Surveying Marketing Department Mon. Feb. 21. 2018  Dr :Mahmoud El Homossany Removable Prosthodontics Objectives of the Lecture Surveying 1- Understand Surveyor tools 2-How to use the surveyor. Surveying Chapter 11 Surveying The Component Parts of Removable Partial Dentures Surveying The Component Parts of Removable Partial Dentures Denture Base Artificial Teeth Supporting Rests Connectors: Major Connectors Minor Connectors Retainers Direct retainers Indirect Retainers 3 1 Surveying It is the procedure of locating and 2 delineating the contour and position of the 5 abutment teeth and associated structures before designing a removable partial 4 denture  Undercut: An undercut is formed when the Survey line base of an object is smaller than its top Undercut Area Undercut Area Surveying Surveying Undercuts on Teeth Non-undercut Area Is A Dig Or A Burrow Lie Below The Height Of Contour, Which Is The Most Bulbous And Convex Part Of The Tooth, Also Called Maximum Bulge or Survey Line The Survey Line is a f Line Outlined On the Cast By A Surveyor Marking the Greatest Prominence Of Tooth Contour Surveying Partially Edentulous Mouth has Types of undercuts Many Undercuts That Result due to I-bulbous Shape Of The Crowns Of Natural Teeth Resulting In Buccal And Lingual Tooth Undercuts Undercuts (Proximal undercuts) 2- The Inclination Of The Long Axes Of Teeth In Relation To A Vertical Line Soft Tissues or bony 3-The Inclination Of Soft Tissues Or Bone Undercuts(on lingual To A Vertical Line side of ridge) 4- Proliferation Of Soft Tissues Covering The Edentulous Ridge Surveying Components Of Metallic Removable Partial Dentures Are Types of undercuts All Rigid, With The Exception Of The 1-Desirable Undercuts Flexible Retentive 2-Undesirable Undercuts Clasp Arm Located In An Undercut Area **All the Undercuts are Undesirable For Retaining The undercuts Except that used for Denture Restoration Against Flexible clasp arm engaging Retention Dislodging Forces tooth undercut Path of Insertion Selection of The Path of Insertion The Most Favorable Path of Insertion (PI) Is PI Is The Direction in Which a Restoration That Perpendicular to the Occlusal Plane Moves From the Point of Initial Contact With the Supporting Teeth to the Terminal Resting Most Patients Tend to Seat Their Position Where the Occlusal Rests Are Dentures Under Biting Force Seated and the Denture Base Is in Contact With the Tissue If Displacement of the Prosthesis Is Anticipated With the Least Displacing Forces Path of Removal The Direction of Movement of the If Undercuts are Present but Not Efficient at Restoration From Its Resting Position to the the Zero Tilt Last Contact With the Supporting Teeth". It Is Another Path of Insertion the Reverse of the Path of Insertion Should Be Decided Surveying Factors Affecting Path of Insertion Interferences - Changing the path of insertion - Contouring the tooth surface - Surgery to remove interfering structures - Retentive undercuts should be equal in depth and permit the location of clasp tips in the gingival third of the tooth - Esthetics Made possible with less clasp metal and less base material displayed Guiding planes  Post Is More Readily Removed by Application of Force Near Its Top Than by Applying Same Force Nearer Ground Clasp retention depends on amount of undercut Level rather than distance below height of contour Surveying Guiding planes Guiding planes *Flat Axial Surfaces In an Occluso-gingival Direction on The Proximal or Lingual Surfaces of Teeth. *Parallel To The Path Of Insertion Help In *Guiding The Prosthesis During Insertion and Removal Surveying The functions of guiding planes Guide the Prosthesis in or Out of Place Without Exerting Excessive Forces Against the Teeth The Frictional Contact of the Prosthesis Against These Parallel Surfaces, Contribute to the Retention of the Prosthesis Provide Bracing and Stability When they are Located on the Axial Lingual Surface of A guide surface should extend vertically for about 3 the Tooth mm, and should be kept as far from the gingival margin as possible Surveying Surveying Minimize Wedging Stresses on the Abutment Teeth Guide the Prosthesis in or Out of Place Without Minimize the Amount of Space Between the Denture and the Exerting Excessive Forces Against the Teeth Tooth Thus Making the Prosthesis More Hygienic Surveying Surveying THE DENIAL SURVEYOR It Is a “Paralleling Instrument Used to Determine the Survey Line of Teeth, Identify and Measure Tooth Undercuts and to Determine the Relative Parallelism of the Aid in Stabilizing the Prosthesis Against Surfaces of Teeth and Other Horizontal Stress Areas on the Cast” Surveying THE DENTAL SURVEYOR Surveying It is a “Paralleling It is the procedure of locating and delineating the instrument enables a contour and person to draw “ a position of the abutment teeth and contour map” on the associated structures before teeth and tissue areas designing a of a cast” removable partial denture Surveying Surveying Dental Surveyor The Location of the Undercut Area Can Be Ney Surveyor Jelenko Surveyor Changed by Changing the Tilting Surveying Surveying Parts of the Dental Surveyor The location of the undercut area can be changed by tilting the cast anteriorly or lateral A- The Base B- Vertical Upright Column Surveying Tools C- Cross Arm with Spindle Housing D- The Vertical Spindle With Tool Holder 1- Analyzing Rods E- Screw To Lock The Spindle F- Tool Holder 2- Carbon Marker H- The Surveyor Table 3- Undercut Gauge M- Ball Retaining Ring N- Tool Rack 4- Wax Trimmer O- Storage Compartment Surveying Surveying Analyzing Rod Surveying Surveying Carbon Marker Undercut Gauges Of an inch ??? of mm. Surveying Undercut Gauge Undercut Gauge Surveying Surveying Wax Trimmer OBJECTIVES OF SURVEYING Surveying Permit an Accurate Charting of the Required Mouth Preparations Surveying Ceramic Veneer Determine the Most Acceptable Path of Placement and Removal Crowns Determine the Relative Parallelism of Teeth Surfaces That Act As Guiding Planes Determine Soft, Bony or Tooth Undercuts and Areas of Interferences Identify and Measure Tooth Undercuts Delineate Height of Contour Trimming Blockout Material Parallel to the Path of Placement Recording the Cast Position Surveying Surveying Machining Cast Restorations Surveying the Master Cast To select the most suitable path of placement by following mouth preparations that satisfy the requirements of guiding planes, retention, noninterference, and esthetics. Surveying Surveying Surveying the Master Cast Surveying the Master Cast To permit measurement of retentive areas To trim blockout material parallel to the and to identify the location of clasp path of placement before duplication terminals in proportion to the flexibility of the clasp arm being used; To locate undesirable undercut Surveying Surveying Factors that Determine Path of Placement and Removal Guiding Planes Retentive Areas Interference Esthetics Surveying PRINCIPLES OF SURVEYING The Prosthesis Can Goes Smoothly Into Place Without Interference After Analyzing the Proximal Tooth Surfaces and Making the Necessary Alteratio Surveying Surveying Recontouring the tooth surface The Location of the Undercut Area Can Be Changed by Changing the Tilting Surveying A Cast in a Tilted Relationship Represents a Path of Placement Toward the Side of the Cast That Is The location of the undercut area can be Tilted changed by tilting the cast anteriorly or lateral Upward Selection of The Path of Insertion The Most Favorable Path of Insertion (PI) Is That Perpendicular to the Occlusal Plane Most Patients Tend to Seat Their Cast at zero tilt. Creation of undercut by tilting cast Dentures Under Biting Force If Undercuts are Present but Not Efficient at the Zero Tilt If Displacement of the Prosthesis Is Anticipated With the Least Displacing Forces Another Path of Insertion Should Be Decided  Selection of the Path of Insertion PROCEDURES of SURVEYING 1- Placement of the Cast Tilting the Cast to 2- Altering the Cast Position Anteroposteriorly To Provide Parallel Proximal Surfaces That May Create Suitable Undercuts Act As Guiding Planes Equalize Undercuts on both Sides of the Arch 3- Tilt the Cast Laterally Until Equal Retentive Place the Clasp Tips in a Better Esthetic Po. Areas Exist on the Principal Abutments Undercut Areas Should Be Present at Both 4- Eliminate Areas of Interference by Reshaping Zero Tilt and the New Tilt Tooth Surfaces Gross Inclination of the Cast to Create 5- Permits a More Esthetic Placement of Apparent Undercuts Should Be Avoided Clasp Arms Than the Othe Surveying After Selection of the Proper Path of Insertion, the Cast Is Secured in Place * Drawing of the Survey Line * Location of the clasp terminals * Blocking the Undesirable Undercuts * Tripoding or Scoring Tripoding the Cast Scoring the Cast Surveying Tripoding Or Scoring are It has been estimated Performed that an error of 0.2 While the mm can be anticipated Master Cast is Still Mounted when a cast with three on the Survey reference points Table Without Changing the Tilt to Preserve the Established Cast Tilt Surveying Surveying Step-By-Step Procedures in Surveying A Diagnostic Cast I-Guiding Planes Surveying Surveying The end result of selecting a suitable II-Retentive Areas anteroposterior tilt should be to provide Alter the cast position by tilting it laterally until similar the greatest combined areas of parallel retentive areas exist on the principal abutment teeth proximal surfaces that may act as guiding planes. Other axial surfaces of abutment teeth may also be used as guiding planes. Surveying Surveying III-Interference III-Interference A mandibular cast is being surveyed, check the Other areas of possible interference to be evaluated are lingual surfaces that will be crossed by a lingual bar those surfaces of abutment teeth that will support or be major connector during placement and removal. Bony crossed by minor connectors and clasp arms. Although prominences and lingually interference to vertical minor connectors may be blocked inclined premolar teeth are the most common causes out, doing so may cause discomfort to the patient’s of interference to a lingual bar connector. tongue and may create objectionable spaces, which could result in the trapping of food. Surveying Surveying III-Interference IV-Esthetics When the retentive area is located objectionably high on the if a choice between two paths of insertion abutment tooth or the undercut is too severe, interference may of equal merit permits a more esthetic placement of clasp also exist on tooth surfaces that support retentive clasps. Such areas of extreme or high convexity must be considered as areas of arms by one path than the other, that path should be interference and should be reduced accordingly. These areas are given preference. When anterior replacements are likewise indicated on the diagnostic cast for reduction during involved, the choice of path is limited to a more vertical mouth preparations one for reasons previously stated. Surveying Modifications of master cast All guiding-plane areas must be parallel to the path of placement, and all other areas that will be contacted by rigid parts of the denture framework must be made free of the undercut by parallel blockout. Relief must also be provided for the gingival crevice and gingival margin. Black regions designate parallel blockout at proximal guide-plane surfaces and relief along the palatal marginal gingiva. Surveying Surveying Relief and blockout of the master cast before duplication. All undercuts involved in the denture design have been blocked out parallel to the path of placement, except the retentive tips of the retainer clasps. Residual ridges have been provided 20-gauge relief for denture base material. Surveying Surveying Surveying Thank You