Checking & Verification of Fixed Prostheses PDF

# Checking and Verification of Fixed Prostheses ## By ## Prof. Dr. ## Lamia Dawood # Evaluation - The completed restoration is cleaned and disinfected. - Removal of the temporary restoration. - Remaining cement should be removed from the prepared tooth surface with an explorer. - The preparation...

# Checking and Verification of Fixed Prostheses ## By ## Prof. Dr. ## Lamia Dawood # Evaluation - The completed restoration is cleaned and disinfected. - Removal of the temporary restoration. - Remaining cement should be removed from the prepared tooth surface with an explorer. - The preparation is rinsed with water and air spray, inspected after drying the area. # Fixed prosthesis should be checked from many aspects: 1. Seating (proximal contact). 2. Marginal integrity. 3. Retention and stability. 4. Occlusion. 5. Contour alignment and Occlusal anatomy. 6. Contour of the pontic and its relation to the mucosa of the alveolar ridge. 7. Connectors. 8. Esthetics. 9. Radiographic checking. # 1- Seating: (Proximal contacts) - The restoration should be able to be seated with little frictional resistance. - Gentle occluding force should be sufficient to complete the seating. # Causes of incomplete seating: - Excessive proximal contact. - Presence of nodules on the fitting surface of the restoration. - Over extension of the gingival margin. - Tight cast. - Faulty assembling and soldering. - Lack of parallelism of abutment teeth. # a) Excessive proximal contacts: - The location, size and tightness of proximal contacts should resemble those of the natural teeth. - Ideally a thin unwaxed dental floss should snap through with resistance but without tearing. - Excessive contact will prevent seating of the restoration and the patient will feel that the restoration is pressing too hard on the adjacent teeth. # Weak contact → Food impaction # i. Excessive tightness in all-metallic restorations: - If a tight contact prevents the seating of an all-metallic restoration, adjustments → a rubber wheel. - The satin finish helps to identify where binding occur. - A shiny spot will appear where adjustment is necessary. - Special quick drying marking liquid or pressure indicating paste can be used to cover the contact surface and on seating the excessive contact area will be detected as the marking layer will be scratched. # ii. Excessive tightness in ceramic restorations: - The area of contact can be identified with red pencil or thin marking tape. - A tight proximal contact in unglazed ceramic is easily adjusted with a cylindrical stone. # iii. Deficient proximal contact: - Deficient contact in all-metallic restorations → usually be corrected by soldering. # iv. Deficient porcelain restorations: - A low fusing "add on" or correction porcelain is used for minor correction. # b. Presence of nodules on the fitting surface of the restoration: ## Detection: - A magnifying lens may be used to examine the fitting surface particularly at the inner angles. ## Causes: 1. Air trapped during investing procedure. 2. Inadequate vacuum during investing. 3. Improper brush technique. 4. Lack of surfactant. 5. Excessive vibration. # Correction: - Small nodule not located in critical areas → should be removed. - Large nodule or situated on the margin → remake # c) Over extension of the gingival margin: - Errors in die making and or wax pattern carving may results in over extending gingival margins of the restoration causing resistance to complete seating. # Correction: - New impressions are taken and new dies and working casts are made. # d) Tight cast: ## Causes: - Improper expansion of the investment due to: - Improper W/P. - Improper spatulation. - No ring liner. - Improper mold heating. - Improper liquid added. ## Detection: - By painting the fitting surface of the restoration by pressure indicating paste → seat the restoration→ paint in the tight areas → scratched due to friction. ## Correction: - If the area of interference is small and well defined it can be reduced → spot grinding. - If the areas of interference are multiple or generalized → Electro-stripping # e) Lack of parallelism of abutment teeth # f) Faulty assembling and soldering: ## Causes: 1. Failure to maintain the proper relationship of the assembled parts of the bridge. 2. Improper heating of the assembly. 3. Improper heat application during soldering. 4. Improper proximal gap. ## Correction - Disassembling → resoldering # Disassembling: - Using diamond disc until the joint become thin enough to be fractured manually. - By heating the solder joint until it melts. # 2. Margin Integrity: - Ideally the completed restoration should go into place without binding of the internal aspect against the occlusal surface or the axial walls of the tooth preparation. - Several techniques are used to detect where casting binds against occlusal or axial walls. - Disclosing wax. - Water soluble marking agents. - Powdered spray. - Air abrasion to form a matte finish surface. - Elastomeric detection pastes: - Similar to silicon impression material. - Obtained in 2 paste system. - Has similar viscosity to final luting agents. # Assessment: - Use sharp explorer. - Held perpendicular to the marginal area. - Moved occluso-cervically across the margin. # Finishing of the margins: - **Subgingival margins:** - Not accessible for finishing in the mouth. - Finished on the die. - Pre-cementation X-Ray is needed. - **Supragingival margins:** - Finished with the casting seated on the tooth. - White stone rotating from the restoration to tooth structure → suitable finished margins. - Burnishing can be made during cementation procedure before initial setting of the cement. # 3. Retention and stability: - Ideally the restoration should have adequate retentive properties. - It should be able to be retained in position by tenso-frictional grip during initial seating. - The stability of a bridge can be verified by placing one finger on one retainer and see whether there is evidence of a rocking action on the other retainer. It should not rock or rotate when force is applied. # The instability maybe due to: - Small nodule → can be corrected. - Distortion → remake. # Causes of distortion: 1. Incorrect handling of wax pattern before investing. 2. Under estimation of a wax relaxation due to induced stresses. 3. Under estimation of setting and hygroscopic expansion. 4. Incorrect positioning of wax pattern in the casting ring. 5. Using force during removal of the restoration from the casting ring. # 4. Occlusion: - It should be checked by the use: - Mylar shim stock to identify presence or absence of occlusal contacts. - Thin articulating paper which will leave a mark on the high spots. - Occlusion should be checked both in centric and eccentric (lateral and protrusive excursions). - Any undesirable eccentric contacts as well as centric interference must be identified. - Occlusal adjustment involving dental porcelain is better to be done in the bisque stage. # Occlusal assessment: - With the restoration out select a pair of index teeth, which hold shim stock. - Mark with black articulating foil and adjust ICP. - Mark with red and adjust excursive interferences and deflections. - Adjustment complete. # Having problems with multiple false occlusal marks because of tall cusp tips → Articulating paper modified with multiple cuts along its long edge. # True inter-occlusal contact leaves a circular mark (like a point of a ball point pen). # A false contact leaves a smudge. # When assessing the occlusion of a single restoration, a clear center may be found within the occlusal markings like a bull’s-eye. # These circular patterns with a clean center are indications of hyper-occlusal contacts for the single restoration and must be adjusted until the contact gets smaller and without a clean center. # In contrast to the insertion of a single crown, when a complete arch of crowns is evaluated for occlusion, the contacts with the bull’s-eye effect are desirable as long as they distributed equally and bilaterally on each crown across the dental arch. # 2- Remount - If clinical evaluation reveals a need for significant occlusal adjustment of multiple restorations, a remount procedure may be indicated. - When extensive restorative dentistry is undertaken, the remount serves to convey the relationships of the restorations and teeth to the dental laboratory. - Advantages: - Occlusal adjustment in an organized manner. - Reduction of the amount of chair time. # Armamentarium for a remount procedure: 1. Impression trays. 2. Irreversible hydrocolloid. 3. Rubber bowl and spatula. 4. Interim luting agent. 5. Petrolatum. 6. Photopolymerizing resin. 7. Stiff wire (e.g., coat hanger wire). 8. Zinc oxide-eugenol occlusal registration paste. 9. Inlay wax or light-bodied reversible hydrocolloid. 10. Facebow transfer equipment. 11. Centric relation recording. # Alternative technique for occlusal adjustment - Using air abrasive unit with aluminum oxide: - Matte finish is obtained on the occlusal surfaces of adjusted casting. and patient asked to close. - Where shiny marks appear, an adjustment is made. - Disadvantage: - Can't differentiate between centric and excursive contacts. - Time-consuming. - Applicable only to cast metal occlusal surfaces. # 5. Contour, Alignment and Occlusal Anatomy: - Contour and alignment should be compared with the neighboring teeth and similar teeth on the opposite side. - **Cervical contour of the retainer:** - **Cervical embrasure form and interproximal contour.** # 6. Contour of the pontic and its relation to the mucosa of the alveolar ridge: - **The pontic should be in passive fit with the ridge:** - The relationship of the pontic to the ridge should be self-cleansing. - Pressure of the pontic against the ridge → blanching of the mucosa. - The pressure can be verified by passing dental floss between the pontic and the ridge antroposteriorly. - **The pontic should have the correct contour that allows the food sweep over the mucosa as massaging and stimulating action and not to impinge directly up → irritation and inflammation.** # 7. Connectors: - **Rigid connectors:** Checked for adequate strength and maintain the correct interproximal relationship. - **Non-rigid connectors:** Checked for adequate retentive qualities and maintenance of corrected interproximal relationship. # 8. Esthetics: - Fixed prostheses must be in harmony with the neighboring natural teeth particularly in form, size, surface characterization and color match. - Therefore Ceramic restoration must be evaluated for: - Contour of the restoration. - Surface characterization. - Color match. # (a) Contour of the restoration: - Check proximal contact relationship and marginal fit of the restoration. - Verify the contour of gingival 1/3 → excessive bulk in this area → P.D. disease. - Thin flexible disc → is used to reduce any over contoured interproximal area. # In anterior teeth the restoration is tried in the patient mouth and evaluation is made: - An average of 1-2 mm of the clinical crown of maxillary central and lateral incisors should be visible when upper lip is relaxed. - Incisal edge of maxillary lateral incisors are 1-2 mm shorter than central incisors. - The “negative space" & incisal embrasures. Their absence ➔ artificial appearance. - Let the patient pronounce the letter “F”, they are made with incisal edges of maxillary central incisors touching at "wet dry line" (The junction of the moist and dry surfaces of the vermilion bonder of the lower lip). - Mark line angles directly on porcelain restoration in bisque stage with red pencil and compare these line angles with the adjacent and contra-lateral teeth. - Evaluate the overall contour, it should matches with the adjacent teeth. Teeth should moisten with saliva to observe light reflection. Moist surfaces reflects light on the same manner as glazed restoration. # (b) Surface characterization: - Dry the teeth and examine their surfaces carefully: - Surface defects can be simulated by grinding the porcelain with diamond stone. - Flat or concave areas will reflect light in a characteristic manner producing high lights. - Avoid over characterizing which makes teeth to look unnatural. # (c) Color match. - Check the color if match or need any modification. # 9. Radiographic Checking: - Indicated to verify gingival adaptation and to make certain that no undetected open margins exist interproximally. # The image depicts two red orchids with a yellow center and dark red streaks. The orchids are in a close up view and their petals are visible. The background is out of focus and appears green. It's a still life painting.