Impression Making & Diagnosis (Midterms) PDF

LESSON 1: IMPRESSION MAKING AND DIAGNOSIS PROSTHO 3 1ST SEMESTER| 2024-2025 |DR. ECON Removing the dentures from the mouth at night for 6 to 8...

LESSON 1: IMPRESSION MAKING AND DIAGNOSIS PROSTHO 3 1ST SEMESTER| 2024-2025 |DR. ECON Removing the dentures from the mouth at night for 6 to 8 CLASSIFICATION OF MUCOSA hours allows keratinization and the signs of inflammation are 1. Masticatory mucosa reduced. 2. Lining mucosa 3. Specialized mucosa CLASSIFICATION BASED ON CONSISTENCY Resilient – tissue is yielding Masticatory Mucosa when pressure is applied; it covering the hard palate reverts to its original form when and residual ridge (well the pressure is released defined keratinized Non-Yielding – tissue has no epithelium and lack of appreciable movement when tissue movement) pressure is applied The mucous membrane Flabby – tissue is easily deformed when pressure is applied and covering the crest of the may not recover its original form or position ridge of a healthy mouth is firmly attached to the periosteum of the bone by the connective tissue of the submucosa. Lining Mucosa RESIDUAL RIDGE Forms 60% of the surface area The shape and size of the residual alveolar ridge is dependent on Non-keratinized the anatomic contour of the patient’s dentate arch. Distensible U, V and Square arch forms Relatively loosely bound IMPRESSION MAKING Found on mobile Impression – negative copy structures like: Cast – positive copy Lips, cheeks, soft palate, alveolar mucosa OBJECTIVES Vestibular fornix, 1. Retention floor of the mouth 2. Stability Specialized Mucosa 3. Support Located in the dorsum of tongue 4. Esthetics Specialized mucosal structures 5. Preservation of remaining structures the lingual papillae and taste REQUIREMENTS IN IMPRESSION MAKING receptors 1. Knowledge on basic anatomy The heterogenous pattern of 2. Knowledge on the basic and reliable technique keratin expression in the tongue is 3. Knowledge in impression materials complex 4. Skills In parts responsible in 5. Management generating the papillary architecture of the lingual epithelium CRITERIAS OF A GOOD IMPRESSION MATERIAL MUCOUS MEMBRANE Safe The quality of the attachment of the MUCOSA varies considerably, Dimensionally Stable and with greater resorption of the cancellous ridge, the Easy to manipulate submucosa is loosely attached to the bone, creating an Resist distortion unfavorable denture situation. Accuracy The tissues also may become quite compressible over the ridge because of resorption of underlying bone According to studies: Stimulation of the mucosa of the residual ridge through toothbrush physiotherapy increases the presence of keratinization PROSTHO 3 LESSON 1 | ALMENANZA | SALAZAR | TRINIDAD 1  LESSON 1: IMPRESSION MAKING AND DIAGNOSIS PROSTHO 3 1ST SEMESTER| 2024-2025 |DR. ECON IMPRESSION MAKING 1. The tissues of the mouth must be healthy 2. The impression should extend to include the entire basal seat within the limits of function of the supporting and limiting tissues 3. If redundant tissue or bony projections of the ridge cannot be surgically removed, space for them must be created within the denture. 4. proper space for the selected impression material should be provided within a properly fitting impression tray Procedure: 5. A guiding mechanism should be provided for correct positioning 1. Primary impression using impression compound of the impression tray in the mouth 2. Baseplate wax adapted to the study cast prior to the 6. A physiological type of border molding procedure should be construction of the custom tray performed by the dentist or by the patient under the guidance of 3. Construction of the custom tray w/ escape holes over baseplate the dentist wax 7. The external shape of the impression must be similar to the 4. Impression using PVS external form of the complete denture Demerits: 1. Short denture borders are readily accessible to the tongue which CLASSIFICATION OF IMPRESSIONS may cause irritation According to use: 2. Lack of border moulding reduces effective peripheral seal 3. Reduced lip support Preliminary Impression 4. Short flanges prevent wide load distribution – for diagnostic purposes, for future reference, 5. Lesser stability of function – to produce a study cast/diagnostic cast for devicing a Applied Feature: treatment plan, for determining conditions of the mouth 1. Helps preservation of oral tissues Final Impression 2. Food can slip beneath the denture 3. Useful in cases with flabby, sharp and thin ridges – Using an individual tray/ custom tray gives an accurate impression producing a master cast which is a cast used to Selective Pressure Impression fabricate / construct dentures. impression in jaw is obtained in some areas readily displaceable – A detailed reproduction. tissue According to pressure exerted on the tissues Boucher 1950 impressed: Combines principle of both mucostatic and mucocompressive Both tissue preservation and retention Mucostatic Impression (minimal pressure technique) Base thorough understanding of the anatomy and physiology of – with zero pressure/ pressureless or negative pressure basal seat impression. Impression material to be used should be the most Free-Flowing material – Main advantage: high regard for tissue health and preservation – Retention mainly from interfacial surface tension PROSTHO 3 LESSON 1 | ALMENANZA | SALAZAR | TRINIDAD 2  LESSON 1: IMPRESSION MAKING AND DIAGNOSIS PROSTHO 3 1ST SEMESTER| 2024-2025 |DR. ECON 3. Final impression made using custom tray and impression compound (greenstick) 4. Fabrication of occlusion rims 5. Insert occlusion rims with PVS held under biting pressure until material sets (borders are molded by asking the patient to do functional movement) Demerits 1. Excess pressure could lead to increase bone resorption 2. Excess pressure applied to peripheries and palate (irritation) 3. Dentures that fit well during mastication tend to rebound when tissue resumes resting state. 4. Pressure on bony ridges result to pain Applied Feature: 1. Tissues recorded in functional positions and denture cannot be dislodged during functional jaw movements 2. Since pressure is applied more on the palate and peripheral tissues, retention will be for short time and will be lost as soon as bone undergoes resorption According to mouth position: Open mouth method – for trays with handle – Muscle movement may be emphasized and can be seen by the operator Closed mouth method – for trays without handle Functional Impression (Pressure impression, – Supporting tissues are Mucocompressive impression technique) recorded in functional rel. – Needs occlusion rim – Greene 1896 – Border holding and final imp. – Theory was proposed on the assumption that tissues recorded under functional pressure provided Based on manipulation of border molding: better support and retention for denture Hand manipulation – Impression trays are without handle – dentist uses hands for manipulation of lips and cheeks only occlusion rim – Done by closing the mouth of the patient – Very good impression technique – These impression will generally lead to a denture that is most stable during function but not at rest Procedure: 1. Primary impression made using impression compound 2. Construction of custom tray( ex. Shellac base plate, self-polymerizing resin, VLC) PROSTHO 3 LESSON 1 | ALMENANZA | SALAZAR | TRINIDAD 3  LESSON 1: IMPRESSION MAKING AND DIAGNOSIS PROSTHO 3 1ST SEMESTER| 2024-2025 |DR. ECON Functional movements Irreversible hydrocolloids – universally used impression materials for primary edentulous impressions. – Patient makes functional movements such as sucking, Imbibition – water is absorbed by colloids causing an enormous swallowing, licking or grinning increase in volume Syneresis – separation of liquid from the colloid material Silicone Putty – high viscosity, it will flow beyond the tray to compensate for underextension of the stock tray and once set it will support itself in this position – Records poor surface detail Impression Cake Compound/ Modeling compound – Thermoplastic material with a high viscosity COMPONENTS OF IMPRESSION MAKING – Material will flow beyond the tray to compensate for Impression tray – most important underextension and will maintain position after it is chilled. Operator – Poor surface detail Impression material – Nonelastic (will cause trauma in severe bony undercuts) 2 Types of Impression Trays: Common faults during impression making Stock tray Upper – pre-fabricated, usually does not have a good fitting made of 1. Tuberosity problem –too wide open mouth metal or plastics 2. Incomplete registration of labial flange Kinds of stock tray: 3. Incomplete registration of palate Perforated – alginate Lower Non perforated – modelling 1. Failure to copy the alveololingual sulcus, short lingual compound extension of the tray Rim-locked – rubber 2. Short Labial Flange impression materials 3. Short Buccal Shelf extension Water-cooled tray – agar agar 4. Trapped air bubbles 5. Too thick or too thin impression 6. Knife edge border Diagnostic Cast Individual tray/Custom tray – tray made for a particular individual Purpose of Custom Tray: 1. minimize impression material distortion (uniform thickness, rigid tray) 2. prevent tissue distortion ( less viscous material, more accurately adapted tray) 3. reduce costs – less impression material is used 4. allow for accuracy by molding the border, resulting in improved retention BORDER MOLDING & FINAL IMPRESSION The reason for a custom impression tray and final impression is to PRELIMINARY IMPRESSION accurately record the denture founding area, including the The preliminary impression should be as accurate as possible and configuration of the denture borders during function overextension of peripheral borders is preferred to underextensions ultimately as a slightly underextended custom tray will be fabricated on this overextended preliminary cast. In making preliminary impression it is advisable to select an impression material that has a relatively HIGH VISCOSITY to compensate more easily for the deficiency of the tray PROSTHO 3 LESSON 1 | ALMENANZA | SALAZAR | TRINIDAD 4  LESSON 1: IMPRESSION MAKING AND DIAGNOSIS PROSTHO 3 1ST SEMESTER| 2024-2025 |DR. ECON Modeling compound stick type MANDIBULAR – commonly used material for border molding. LABIAL – patients make aggressive movements of the lips : puckers, Low cost sneers, opens wide, grimaces and smiles. Prominence of frenum Ability to place It incrementally should be noted and duplicated Observe the surface and trim it back or BUCCAL SHELF – The patient opens wide, grimaces, and puckers add material MASSETERIC NOTCH – The patient closes against the hand on the Impression waxes, Polyether and silicone chin materials RETROMOLAR PAD – The patient opens wide and closes against the hand on the chin RETROMYLOHYOID SULCUS – Push compound into fossa area; patient licks lower lip and right and left cheeks and swallows LINGUAL BORDER AND LINGUAL ANTERIOR BORDER – the patient licks lower and upper lip and right and left cheeks and pushes tongue against the handle of the tray or the clinicians thumb. The border will gently curve under the tongue at midbody MAXILLARY LABIAL – patients make aggressive movements of the lips : puckers, sneers, opens wide, grimaces and smiles. Prominence of frenum should be noted and duplicated POSTERIOR LATERAL – Move mandible right and left. Width and height should be noted and duplicated HAMULAR NOTCH – Push compound into the notch. Then the patient opens wide and closes against hand on chin. Vertical notch of the pterygomandibular raphe should be noted in impression POSTERIOR VIBRATING LINE – Observe line with patient saying ah and trim compound to this line or area. Palpate the displacement bilaterally onto the displaceable tissues that border the hard palate and soft palate junction and place compound in a butterfly shape border seal PROSTHO 3 LESSON 1 | ALMENANZA | SALAZAR | TRINIDAD 5  LESSON 1: IMPRESSION MAKING AND DIAGNOSIS PROSTHO 3 1ST SEMESTER| 2024-2025 |DR. ECON FINAL IMPRESSION Alginate (irreversible hydrocolloid) Non-Elastic Impression Materials most widely used impression material in dentistry substitute for agar when there is scarcity during wwii Impression Plaster ease of manipulation Mucostatic impression material for final impression material of choice for preliminary impression Calcium sulphate hemihydrate Ca.SO4 sol-gel reaction of potassium alginate and calcium sulphate H2O – Calcium sulphate dihydrate trisodium phosphate is the retarded Ca.SO4 2H2O Elastomeric Impression Material Mechanical limitations of impression plaster preclude its regular use as PVS (Polyvinyl Siloxanes) 1950 traditional impression material low, medium, high and very high consistencies materials are based on silicone prepolymers that carry vinyl and Zinc Oxide Eugenol Impression Paste hydrogen side groups, which can polymerize by addition powder and liquid form (2 paste polymerization system) chloroplatinic acid (platinum salt catalyst) activates the reaction setting shrinkage of to 100 degree celsius and upon cooling the sol transforms into a condensation > addition > polyether gel at a gelation temperature water cooled tray PROSTHO 3 LESSON 1 | ALMENANZA | SALAZAR | TRINIDAD 6  LESSON 1: IMPRESSION MAKING AND DIAGNOSIS PROSTHO 3 1ST SEMESTER| 2024-2025 |DR. ECON LABORATORY SAMPLE Beading w/ Posterior Palatal Seal (U) Study / Diagnostic Cast with Outline Master / Working Cast with Outline Wax Block Out Custom Tray Border Molding PROSTHO 3 LESSON 1 | ALMENANZA | SALAZAR | TRINIDAD 7  LESSON 1: IMPRESSION MAKING AND DIAGNOSIS PROSTHO 3 1ST SEMESTER| 2024-2025 |DR. ECON TYPES OF CAST Study / Diagnostic Casts A life size production of a part or parts of the oral cavity and/or facial structures for the purpose of study and treatment planning Master / Working Casts A cast formed of a prosthesis for the purpose of mounting on an articulator Refractory Casts A cast made of a material that will withstand high temperatures without disintegrating (investment cast) POSTERIOR PALATAL SEAL Final Impression Created at the posterior periphery of the denture, by creating pressure on the soft tissues of the hamular notch, the anterior soft palate along its attachments to the horizontal hard palate and onto the hard palate on either side of the posterior nasal spine. POST DAM – Surface addition made on the posterior portion of the upper denture on the tissue side or an acrylic elevation at the posterior end of the upper denture. Vibrating Line - the imaginary line across the posterior part of the palate marking the division between the movable and immovable tissue of the palate which can be identified when the movable tissue is moving Anterior vibrating line CAST FABRICATION & OUTLINING OF CAST Posterior vibrating line Anterior Vibrating Line Definitions - imaginary line across the posterior part of the palate marking the Cast division between the movable and immovable tissues over the hard it is a life-size likeness of some desired form palate and the slightly movable tissue of the soft palate. Method of Locating A.V.L: Die Instructing the patient to say “AH” with the positive reproduction of the form of a prepared tooth in a short vigorous burst due to projection any suitable substance of the posterior nasal spine. * the Cast Prerequisites anterior vibrating line is not a straight Void free line between both Hamular Process Distortion free Posterior Vibrating Line Reproduce both prepared and it is an imaginary line as junction of the aponeurosis of tensor veli unprepared surfaces palatini muscles in the muscular portion of the soft palate Occlusal surface of all teeth must It represent demarcation between the part of soft palate that has allow articulation limited or shallow movement during function and the remainder of All relevant soft and hard tissue must soft palate that is markedly displaced during functional movement be involved Method of Locating A.V.L: The side walls should be vertical or Instruct the patient to say AH in a short vigorous burst in normal slightly tapered outward unexaggerated fashion. The posterior VL marks the most distal Peripheral roll : 3-4mm extension of the denture base. Edge of the cast : 3-4mm Base of the cast : 15-16mm at the thinnest point Tongue space should be flat and Classification of Palate: smooth PROSTHO 3 LESSON 1 | ALMENANZA | SALAZAR | TRINIDAD 8  LESSON 1: IMPRESSION MAKING AND DIAGNOSIS PROSTHO 3 1ST SEMESTER| 2024-2025 |DR. ECON The Tissue can be displaced several millimeters anterior to the vibrating line in a Butterfly shape on either side of the palatal Interfacial Surface Tension – resistance to separation possessed suture. by the film of liquid between two well-adapted surfaces. It is found House described 3 Classifications of soft palates: in the thin film of saliva between the denture base and the mucosa Class I palate is the most favorable denture retention. Soft of the basal seat and is quite similar in its action to cohesion and to palate is horizontal as a capillary attraction. extend posteriorly with It depends on the existence of a saliva/air interface at the minimum muscular terminus of the liquid/solid contact. Therefore it does not play activity as important a role in retention of the mandibular denture as Class II palate – palatal much as for the maxillary one because of the presence of saliva contour lie between Class on both sides of the peripheral seal in the mandibular I and Class III prosthesis. Class III palate – it is seen Capillary attraction – is a force (developed because of surface in conjugation with a high tension) that causes the liquid to become elevated or depressed V shape palatal vault. when it is in contact with a solid. When the adaptation of the Purposes of tissue-displacing nature of the PPS: denture base to the mucosa on which it rests is sufficiently close, the space filled with a thin film of saliva acts like a capillary tube Recess the denture border in the posterior to minimize the end and helps retain the denture. of the denture to the patient’s tongue during swallowing and Atmospheric pressure –it has been called suction because it is a speaking resistance to the removal of dentures from their basal seat; but Create a border seal to decrease the risk of dislodgement of the there is no suction or negative pressure , except when another denture upon speaking and mastication force is applied. Counter the polymerization shrinkage that occurs in processing For atm pressure to be effective the denture must have a of the denture that pulls the processed base away from the cast perfect peripheral seal along the palate. Oral and Facial musculature – musculature provides Function of PPS: supplementary retentive forces provided that the prosthetic teeth are positioned in the neutral zone between the cheeks and the Stability tongue and the polished surfaces of the dentures properly shaped – the main function of PPS is to maintain contact with the anterior Therefore the shape of the buccal and lingual flanges must portion of the soft palate (the tissue under go shallow conform to the musculature to fit against the denture and displacement) during functional movement of the stomatognathic thereby reinforce the border seal system (that is mastication, deglutition and phonation) Undercuts, rotational insertion paths and parallel walls – modest undercuts combined with the relative resiliency of the mucosa and Retention submucosa can enhance retention of prosthesis – maxillary denture main purpose of PPS Gravity – In an upright position of the patient, gravity may act as a Factors of Retention of Dentures retentive force for the mandibular denture but as displacing force Adhesion – the physical attraction of unlike molecules for each for the maxillary one. other. It acts when saliva wets and sticks to the basal surface of Cast metal base may theoretically increase the retention of the dentures and at the same time, to the mucous membrane of the mandibular prosthesis because of its increased mass, but its basal seat. benefits should be highly weighted against its limitations. The effectiveness of adhesion depends on the close adaptation of the denture base to the supporting tissues and Compressibility the fluidity of the saliva. The amount of retention supplied by – it also reduces food accumulation beneath the posterior aspect adhesion is directly proportionate to the area covered by the of denture owing to proper utilization of tissue compressibility. denture Comfort – reduce patient discomfort contact occur between dorsum of the Cohesion – the physical attraction of molecules for each other. It is tongue and posterior end of denture base a retentive force because it occurs in the layer of saliva between the denture base and the mucosa. To strengthen or reinforce the weakest portion of Effectiveness depends on the close adaptation of the denture the denture base base to the supporting tissues and directly proportional to the area covered by the denture. PROSTHO 3 LESSON 1 | ALMENANZA | SALAZAR | TRINIDAD 9  LESSON 1: IMPRESSION MAKING AND DIAGNOSIS PROSTHO 3 1ST SEMESTER| 2024-2025 |DR. ECON Techniques for the Placement of PPS: Conventional Approach Fluid Wax technique BOXING METHODS Wax Boxing Method - Effective for zinc oxide paste impression - Beading Grip wax, Orthodontic tray wax, and utility wax are used for beading an impression Procedure: Place the impression such that ridge portion is parallel to the bench top Fill the tongue space with wax and seal it 3 4mm below the Caulking Compound and Paddle Boxing Method border The impression is boxed on a paddle and wax and caulking Adapt 4mm wide beading wax 3-4 mm below the border compound is used for beading Warm boxing wax until flexible The beading should be 4-5mm wide Seal the ends to the underlying layer of wax Fold a metal boxing strip around the impression Check the boxing for adequate width, height, border and Secure with rubber band sealing Procedure: Check for leaks Strips of caulking compound rope to bead impressions (3-4 mm Pour the impression below border) The beading should be 4-5mm wide Fold a metal boxing strip around the impression (13mm above highest point on impression) Secure with rubber band Seal the caulking compound to the boxing strip Pour the impression with stone Dental Plaster and Pumice Boxing Excellent for rubber based silicones Procedure: Mix a 1:1 mix of dental plaster and pumice Place a patty of it on a glass slab Settle the impression into the patty till 3-4 mm below border Remove excess material Border is 4mm wide DENTURE BASE Adapt boxing wax (height 13mm above the highest point on the Record Bases and Occlusion Rims impression) Paint plaster surface with separating medium Record Bases Check for leaks Generally a temporary form that closely resembles the final base Pour the impression with stone of the denture under construction. After setting place in warm water It is used for recording maxillomandibular jaw relationships and Adjust the dimension on a cast trimmer for setting artificial teeth. Part of CD that rests on ridges or denture areas which supports the teeth or where the teeth are arranged. PROSTHO 3 LESSON 1 | ALMENANZA | SALAZAR | TRINIDAD 10  LESSON 1: IMPRESSION MAKING AND DIAGNOSIS PROSTHO 3 1ST SEMESTER| 2024-2025 |DR. ECON Processing of Denture Base Investing Prepare the flasks for investing the wax pattern by applying separating medium on the inside part of the upper and lower halves, knock-out plate and cover of the flask Soak the cast in water until it is entirely wet. Do not over soak, as this will cause the cast to etch. Apply separating medium to the base Criteria for Recording Bases Mix POP and the fill the sides of the lower half of the flask, leaving Well adapted and accurately formed to the master cast the center portion with an amount of plaster mix just enough to Stable both on the cast and in the mouth accommodate the cast Free of voids or projections on the surface that contacts the oral Press the cast at the center of the lower half of the flask. The mucosa bottom of the cast must touch the base of the flask. See to it that Reduced to approximately a 1 mm thickness both over the crest the land area is slightly above or at level with the rim of the flask and the facial slope of the ridge to prevent the base from Using the plaster spatula, work around the cast so that the plaster interfering with the placement of the artificial teeth is smoothed even with the base of the cast. Contour the plaster so Approximately 2 mm in the hard palate area of the maxillary base that no undercut around the cast is present and the lingual flange of the mandibular base for rigidity Allow to partially set. Moisten a finger and complete the Easily removed from the cast smoothening of the lower half. Let the plaster set completely Smooth and rounded and must reproduce both the contours and Apply separating medium all around the plaster investment and the dimensions of the reflections of the final cast allow it to dry. Fabricated from materials that are dimensionally stable Secure the upper half of the flask to the lower part. Be sure that there is metal to metal contact between them. Clean the rim with a MATERIALS FOR RECORDING BASES sharp knife if the plaster investment interferes with this or re-contour the investment to accommodate the upper half Temporary Base Mix plaster of paris and pour it onto the upper half. Place the – should be reinforced and stabilized flask on a vibrator to ensure that plaster flows to the crevices, thus Shellac reducing the chances of air bubble formation. Add plaster until the Self Curing acrylic flask is full, to complete the investment. Put the flask cover and Vacuum formed vinyl or polystyrene firmly tap it to allow excess plaster to escape. Allow the plaster to Baseplate wax completely set. Permanent Bases Repeat the procedure for the other cast. Take note that when – serves like temporary baseplate in registering jaw investing the mandibular cast, the posterior segment is higher. relations but during processing it’s not discarded anymore Bring plaster to this area using a plaster spatula and contour it Processed acrylic resin further until free of undercuts. Smoothen the plaster to the cast Gold Wax Elimination and Mold Space Preparation Chromium Cobalt alloy LABORATORY SAMPLE Chromium nickel alloy FABRICATION OF DENTURE BASES 1. Shellac 2. Self cure 3. Permanent base PROSTHO 3 LESSON 1 | ALMENANZA | SALAZAR | TRINIDAD 11  LESSON 1: IMPRESSION MAKING AND DIAGNOSIS PROSTHO 3 1ST SEMESTER| 2024-2025 |DR. ECON OCCLUSION RIM A wax form used to establish accurate maxillomandibular jaw relations and for arranging the artificial teeth to form trial denture. Tentative blueprints that assist the dentist and the dental laboratory technician throughout the many phases of denture construction They also help determine the length and the width of the artificial teeth, proper lip support, the midline of the arch Purpose of OCR: Determine the ARCH FORM (Neutral Zone) Establish the level of Occlusal Plane Register preliminary jaw relations (maxillo-mandibular relations) Restore facial contour, Esthetics (lip and cheek support) Selection of size of teeth High Lip line –highest position a lip can assume when smiling, basis of length of incisor Midline –where central incisors will meet Setting teeth NEUTRAL ZONE / ARCH FORM Wilfred Fish – concept of neutral zone in complete denture construction “Natural teeth occupy a zone of equilibrium, with each tooth assuming a stable position that is the result of all various forces acting on it. Consequently, when natural teeth are replaced by artificial teeth, it is logical to set the artificial teeth in a position as close as possible to the one the natural teeth occupied” How to determine the Neutral Zone? The best guide for determining the arch form is to consider the pattern of bone resorption where the teeth are lost and the use of anatomical landmarks that are relatively stable in position MANDIBULAR ARCH Bone loss tends to occur on the labial side of the anterior residual ridge. In the premolar region buccal and lingual sides of residual ridge In the molar region lingual side of ridge PROSTHO 3 LESSON 1 | ALMENANZA | SALAZAR | TRINIDAD 12  LESSON 1: IMPRESSION MAKING AND DIAGNOSIS PROSTHO 3 1ST SEMESTER| 2024-2025 |DR. ECON Residual ridge more lingually placed in the anterior region and more buccally placed in the posterior region OCR is contoured labial to the ridge in anterior, over the ridge in the premolar region and slightly lingual in the molar region Lines should be drawn on the mandibular cast before the OCR is tried in the mouth. One line is drawn from the lingual side of the retromolar pad and extended anteriorly to a point just lingual to the crest of the ridge in the premolar region. Positioning the lingual surface of teeth and lingual surface of your OCR. Establishing the Level or Height of the Occlusal Plane Occlusal Table – food is triturated in the mandibular occlusal surfaces Modiolus – “meeting place” of eight muscles Becomes fixed everytime the buccinator muscle contracts which is a natural accompaniment of all chewing efforts. Bell’s Palsy (cranial nerve 7)/ Inc. Salivation after an IAN block The corners of the mouth are marked on the occlusion rims to MAXILLARY ARCH provide the dentist and technician with anterior landmarks for the Optimal neutral zone determination is still mandatory for speech height of the 1st premolars. and esthetic purposes. The Mandibular molars is usually at level corresponding the 2/3rds Bone reduction usually occurs on the labial and buccal areas of the of Retromolar Pad maxillary residual ridge. The residual edentulous ridge is usually The Maxillary Occlusion Rim is next adjusted to meet evenly with palatal to the original location of natural teeth. the Mandibular Rim. Maxillary teeth should be labial and buccal to the edentulous Following determination of the preferred VDO, one or both rims ridge if they are to be placed in the neutral zone and occupy the might have to be slightly augmented or reduced until an adequate position of their predecessors functionally determined Interocclusal Distance is obtained. Rim is usually parallel to the interpupillary line anteriorly and VDO – established in the presence of a healthy natural dentition camper’s line posteriorly. as part of the process of jaw development and maturation. Simulate proper length and lip support by contouring the labial In people who have lost their natural teeth and must wear aspect of the maxillary occlusion rim. dentures it is established by the vertical height of the two Incisal Edges of maxillary anteriors is 8 to 10 mm from the incisive dentures when the artificial teeth are in contact. papilla TEST/METHODS THAT AIDS THE DENTIST IN ESTABLISHING THE Vernier Caliper CORRECT VDO BY MEANS OF OCR.: 1. Visual Observation of the space between the rims when the mandible is in its physiological rest position 2. Judgment of the overall esthetic facial support 3. Phonetic test that include observations when the “s” sound is enunciated accurately and repeatedly –the average speaking space *old dentures can be can be used for comparison Vertical Dimension of Rest (VDR) –physiologic rest position of the mandible (established by muscles and gravity). It is the postural relationship of the mandible to the maxillae and the teeth do not determine it. PROSTHO 3 LESSON 1 | ALMENANZA | SALAZAR | TRINIDAD 13  LESSON 1: IMPRESSION MAKING AND DIAGNOSIS PROSTHO 3 1ST SEMESTER| 2024-2025 |DR. ECON The difference between your VDR and VDO will determine the MMR / Maxillo-Mandibular Relation amount of LOST VERTICAL DIMENSION. INTEROCCLUSAL DISTANCE/ FREEWAY SPACE = 2 TO 4 mm METHODS in Determine VDO: SWALLOW TEST – let the patient sit in an upright relaxed position head unsupported. After insertion of the properly contoured OCR, tell the patient to swallow and let the jaw relax. When relaxation is Record on Cast obvious the lips are parted to reveal how much space is present. PHONETICS TEST – pronounce ch, s and j sounds brings the anterior teeth close together LABORATORY SAMPLE Occlusion Rim Construction Mounting on Cast Fitting of Maxillary Occlusion Rim Establishing the Level or Height of the Occlusal Plane Placement of High Lip line, Canine line, and Midline PROSTHO 3 LESSON 1 | ALMENANZA | SALAZAR | TRINIDAD 14