RESTORATIONS IN ENDODONTIC Epita S. Pane Cons Dept FKG USU
Reasons for extraction of endodontically treated teeth Vire, 1991
Reasons for extraction of endodontically treated teeth Vire, 1991
Klein et al (1996) Evaluated 742 root canal fillings Success rate of Defective coronal restoration + inadequate fillings 46% Defective restoration + good filling 71% Good restoration + inadequate fillings 79% Good restoration + good fillings 86% Quality of coronal seal had as great influence on success as the quality of root canal treatment
Fracture Risk Fracture of endodontically treated teeth are frequently Attributed to reduced physical properties of the dentin. No difference between the strength of dentin of endodontically treated teeth and that of vital teeth
Cuspal flexure
Hansen et al (1990) The altered mechanical properties of the prepared teeth increase its susceptibility to fracture. 20 years observation of amalgam restoration. Teeth with MOD restoration fractured > than MOD with intact marginal ridges. 30-40% Premolars were still intact at the end of observation period. Teeth with smaller restorations had a much higer survival rate (80%).
Effect of coronal coverage on survival rate (1-10 years) Maxillary Mandibular Anteriors Premolars No crown Crown Molars 0 20 40 60 80 100 % Survival 0 20 40 60 80 % Survival 100 Sorensen and Martinoff, 1984
Linn and Messer (1994) MOD amalgam restorations reduced the danger of fracture and increased the strength of prepared teeth by 61-82%. Cast partial veneer restorastion 125%. Amalgam restoration that covered the cusps 102-175% Endodontically treated posterior teeth should be restored with at least a metal casting that ecnampesses the cusps
Panitvisai and Messer (1995) Type of access cavity and final restoration influence the risk of fracture. An endodontic access preparation further reduces the strength of the crown by half.
Types of restoration ANTERIOR TEETH Composite Resin Glass Ionomer Cement Crown Placement of a crown reduced its risk of fracture by only 2%.
Types of restoration POSTERIOR TEETH Amalgam Composite Resin Placement of a NO crown 38-48% Crown With crown, less than 10% for premolars, 5% for molars.
Minimizing cuspal flexure Three restorative designs Amalgam Amalgam overlay Cast gold overlay
Posts Use or not to use?
Plasmans et al (1988) Using 7mm-long post-cores Fracture resistance: the highest cast post-core system, followed by prefabricated posts +composite cores = no posts with composite builtup extending 3mm into the canal.
decleen (1992) Studies showed that the preparation of post space further weakens the tooth structure, and the placement of the post does not leave the tooth any stronger that it was before the preparation was made Post anchored in the root canals have no strengthening effect on the roots and only serve to provide additional retention for the core and artificial crowns.
Types of posts Parallel sided > retention than tapered posts. Parallel sided provide better distribution of force and lower risk of fracture. Tapered posts are indicated in mandibular anterior teeth with small diameters. Threaded posts provided the best retention, vertival fracture is greater.
Methods of gutta percha removal Mechanical Hot instruments Rotary instruments (gates glidden bur, Peeso reamer) Chemical Solvent
Length of remaining gutta percha Kvist et al 1989: 3mm Hiltner et al 1992: 4mm When the length of root canal filling was 5 mm, the rate of failure with periapical lesions was less than 10%, but when only 2mm remaining, the rate was almost 30%
Post space preparation Using pilot drill of the post system Final length should be at least as great as the lenghth of the final crown. Guidelines: It should measure 2/3 of the total canal length. It should be as long as the future crown length. It should equal half of the bone-supported root length. Marginal: at least 2mm of root dentin should surround the cast post (Ferrule Effect) Create a flat surface around the entrance to the post space Monitoring radiograph with post inserted.
Post cementation Canal is rinsed with Natrium Hypochlorite and dried with paper point. The selected post is coated with cement. Rotated and screwed into place.
Cementing agent 1. Polycarboxylate cement 2. Zinc Phosphate cement 3. Glass Ionomer cement 4. Composite cement Leakage: 4 > 3 > 2 & 1
Core Buildup The cavity is etched and bonded Composite resin core is built up over the fins radiating from the coronal portion of the posts
Types of core materials Composite Resin Amalgam Glass Ionomer Cement : Not recommended
Crown preparation
ASIGNMENTS Group 1. Read and write about how to prepare a cavity of Anterior tooth for porcelain fused to metal full crown Group 2. Read and write about how to prepare a cavity of Posterior teeth for full metal crown Group 3. Read and write about causes of tooth discoloration. Group 4. Read and write about Walking Bleach technique Group 5. Read and write about Thermocatalytic bleaching
Group 6. Read and write about Nightguard vital bleaching Group 7. Read and write about Bleaching materials Group 8. Read and write about Bleaching mechanisms Group 9. Read and write about Bleaching complications Group 10. Temporary restoration in Endodontic Treatment.
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