Mechanical weakening of devitalized teeth: three-dimensional Finite Element Analysis and prediction of tooth fracture (original) (raw)
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Journal of Endodontics, 2010
Introduction: The aim of this study was to investigate and compare stress distribution in various degrees of curved roots with different post and restorations by finite element analysis (FEA). Methods: Sixteen 3dimensional FEA models were created and adapted by using computer software based on external anatomy of mandibular second premolar. A 50-N load was applied. Tensile and compressive stresses were plotted. Results: The stress distribution pattern showed that degrees of root curvature in this study (15, 30, and 45 degrees) had little effect. When the elastic modulus of post and core materials was similar to that of root dentin, tensile stresses were low and concentrated on the external root surface. With higher elastic modulus of materials, tensile stresses were increased and concentrated on the post and post apex. Conclusions: Within the limitations of this study, the suitable restoration in endodontically treated mandibular premolar with limited loss of tooth structure was resin composite that was filled in the coronal third of the root canal. However, when the post and core were indicated, the glass-fiber post and resin composite core were the materials of choice for restoration. (
Influence of Cavity Geometry on the Fracture Strength of Dental Restorations: Finite Element Study
Applied Sciences, 2021
The main purpose of this work was to analyze the stress distribution in premolars restored with indirect IPS Empress® CAD onlays or inlays. The three-dimensional geometry of a human first premolar was created using modeling software. The tooth fixation system was simulated through box geometry, comprising a cortical bone layer with 2 mm of thickness over a layer of trabecular bone with 15 mm of thickness. The tooth had the following approximated crown dimensions: 10.35 mm buccolingual length; 7.1 mm mesiodistal width; and 7.0 mm cervico-occlusal height. The mesio-occluso-distal (MOD) cavity preparations followed the suggestions available in the literature. The cement geometry was modified to include cohesive zone models (CZM) to perform the adhesive joint’s strength prediction. The loading body was created assuming contact between the food bolus and the tooth surface. Numerical solutions were obtained by performing static analysis and damage analysis using the finite element method....
Brazilian Dental Journal, 2013
The aims of this study were to evaluate the effect of root canal filling techniques on root fracture resistance and to analyze, by finite element analysis (FEA), the expansion of the endodontic sealer in two different root canal techniques. Thirty single-rooted human teeth were instrumented with rotary files to a standardized working length of 14 mm. The specimens were embedded in acrylic resin using plastic cylinders as molds, and allocated into 3 groups (n=10): G (lateral) -lateral condensation; G (single-cone) -single cone; G (tagger) -Tagger's hybrid technique. The root canals were prepared to a length of 11 mm with the #3 preparation bur of a tapered glass fiber-reinforced composite post system. All roots received glass fiber posts, which were adhesively cemented and a composite resin core was built. All groups were subjected to a fracture strength test (1 mm/min, 45º). Data were analyzed statistically by one-way ANOVA with a significance level of 5%. FEA was performed using two models: one simulated lateral condensation and Tagger's hybrid technique, and the other one simulated the single-cone technique. The second model was designed with an amount of gutta-percha two times smaller and a sealer layer two times thicker than the first model. The results were analyzed using von Mises stress criteria. One-way ANOVA indicated that the root canal filling technique affected the fracture strength (p=0.004). The G (lateral) and G (tagger) produced similar fracture strength values, while G (single-cone) showed the lowest values. The FEA showed that the single-cone model generated higher stress in the root canal walls. Sealer thickness seems to influence the fracture strength of restored endodontically treated teeth.
A common method of restoring a tooth after root canal treatment is a coronal-radicular buildup and a subsequent cast restoration. 32 When a large quantity of intact tooth structure is present, using the adhesive systems makes a more conservative and defect-oriented restorative technique possible today. On the other hand, intracoronal restorations may not be able to bear the same load as an undamaged tooth, 18 even if sophisticated adhesive techniques are used. More than 20-year-old clinical data 33 and results from a retrospective clinical study indicated a higher medium-to long-term survival rate for crowned root-canal treated teeth vs non-crowned ones. 1 Yet the preparation of a full coverage crown often poses new problems on such teeth; the last remnants of coronal dental hard tissues around the endodontic access cavity may be lost, which could compromise retention of the full coverage crown. In most of the root-canal treated teeth, the use of root canal posts is thought to be necessary, which again may weaken the root and might put the tooth at risk for operational errors. 23,28 Moreover, no sig-Purpose: To evaluate marginal quality, fracture modes, and loads-to-failure of different overlay restorations in rootcanal treated molars in a laboratory setup.
Fracture strength and fracture patterns of root filled teeth restored with direct resin restorations
Journal of Dentistry, 2011
Objective: To compare fracture characteristics of root-filled teeth with variable cavity design and resin composite restoration. Methods: 80 extracted intact maxillary premolars were divided randomly into eight groups; (1) intact teeth; (2) unrestored MOD cavity; (3) unrestored MOD cavity plus endodontic access through the occlusal floor; (4) unrestored MOD plus endodontic access with axial walls removed; (5) MOD restored with resin composite; (6) MOD plus endodontic access, resin composite; (7) MOD plus extensive endodontic access, resin composite; (8) MOD plus extensive endodontic access, GIC core and resin composite. A ramped oblique load was applied to the buccal cusp in a servohydraulic testing machine. Fracture load and fracture patterns were recorded. Fracture loads were compared statistically using 1-way ANOVA, with Dunnett test for multiple comparisons. Results: Unrestored teeth became progressively weaker with more extensive preparations. Endodontic access confined within the occlusal floor did not significantly affect strength compared to an MOD cavity. Loss of axial walls weakened teeth considerably [292 + 80 N vs 747 + 130 N for intact teeth]. Restoration increased the strength of prepared teeth particularly in teeth without axial walls. Teeth with a GIC core were not significantly weaker than intact teeth [560 + 167 N]. Failures were mostly adhesive at the buccal interface, with the fracture propagating from the buccal line angle of the occlusal floor (MOD and MOD plus access groups) or of the proximal box (axial wall removed). Conclusions: Direct restorations increased fracture resistance of root filled teeth with extensive endodontic access. Both restored and unrestored teeth showed similar fracture patterns.
Applied Bionics and Biomechanics, 2018
Objective. The purpose of this study was to test different restoration combinations used for constructing fractured endodontically treated incisors by reattaching their fractured fragments. Methods. Seven types of 3-D FEM mathematical root canal-filled models were generated, simulating cases of (OB) reattaching fractured fragments; (CrPL) reattaching fractured fragments + ceramic palatinal laminate; (CmPL) reattaching fractured fragments + composite palatinal laminate; (CM) reattaching fractured fragments + coronal 1/3 of the root was filled using core material; (BP) reattaching fractured fragments + glass fiber post; (CP) composite resin restoration + glass fiber post; and (OC) composite resin restoration. A 100-N static oblique force was applied to the simulated teeth with 135° on the node at 2 mm above the cingulum to analyze the stress distribution at the tooth. Results. For enamel tissue, the highest stress values were observed in model BP, and the lowest stress values were obs...
Finite element analysis of devitalized teeth
Elimination of a large part of dental tissues during root canal treatment affects the mechanical behavior of devitalized teeth. The present study addresses how much dentin removal affects changes in mechanical behaviors of the intact tooth and tooth with root canal treatment. In order to estimate the tooth weakening, we performed aн experimental assessment of critical force and numerical Finite Element Method (FEM) analysis with the intention to analyze stresses distributions. The results showed that root canal treatment had significant influence on stress distributions. By analysis of retrieved results, it is concluded that this study is an efficient framework which could be applied in a number of different cases, so that practitioners could analyze and prepare the treatment with more certainty.
A comparison of intracanal stresses in a post-restored tooth utilizing the finite element method
Journal of Endodontics, 1992
The finite element method was used to compare stresses along the inner canal wall in four twodimensional models of an average maxillary central incisor. The four models evaluated were an intact incisor, an endodontically treated incisor, an endodontically treated crown-restored incisor, and a cylindrical post and crown-restored incisor. A horizontal static force, 1 Newton in magnitude, was applied to the lingual surface of each model and the maximum tensile, compressive, and shear stresses were calculated using the general purpose finite element program PAFEC 75. Results indicate that the stress patterns within the root are altered as a result of post insertion. Specifically, the maximum bending stresses are associated with the apical termination of the post, and post placement does not result in a uniform distribution of stress along the canal wall.
Journal of Prosthodontics, 2008
The aim of this study was to evaluate the effect of endodontic and restorative treatment on the fracture resistance of posterior teeth. Materials and Methods: Fifty intact premolars were selected and randomly placed into five groups (n = 10): G1, intact teeth (control); G2, mesial-occlusal-distal (MOD) preparation; G3, MOD preparation restored with composite resin (Z-250, 3M ESPE); G4, MOD preparation and endodontic treatment; and G5, MOD preparation, endodontic treatment, and composite resin restoration. The specimens were submitted to an axial compression load in a mechanical test machine (EMIC), at a speed of 0.5 mm/min. Fracture patterns were analyzed at four levels. Five 2D numerical models were created by Ansys 10.0 for finite element analysis (FEA). Results: Mean values of compressive strength for all groups were (Kgf): G1 (83.6 ± 25.4); G2 (52.7 ± 20.2); G3 (82.1 ± 24.9); G4 (40.2 ± 14.2); G5 (64.5 ± 18.1). Statistical analysis (ANOVA and Tukey's test) showed that fracture resistance of G1 was significantly higher than that of G5, G2, and G4. Resistance of G3 was also higher than that of G2 and G4. Results showed that the tooth resistance is completely maintained when MOD preparation is restored with composite resin and partially recovered when MOD preparation associated with an endodontic access is restored in the same way. The endodontic treatment and composite resin restoration influenced stress distribution in the dental structure. Conclusions: Composite resin restoration plays an important role in recovering tooth strength. With regard to fracture mode, restoration and endodontic treatment increased the incidence of periodontal involvement, which was demonstrated by association with the finite element mechanical test method.
The Journal of Contemporary Dental Practice, 2021
Aim and objective: To compare the fracture resistance in teeth managed by root canal treatment after restoring with different types of onlays, inlays, and endocrowns prepared with hybrid ceramics and pulp chambers restored with fiber-reinforced composite and resin composite that were radiopaque, light-cured, and flowable. Materials and methods: The present study was carried out on 252 extracted mandibular molars. All the specimens were divided into six groups randomly. Each group consisted of 42 specimens. Group 1 consisted of intact teeth without any access cavity. It was the control group. Group 2 consisted of teeth with endocrown and empty pulp chamber. Group 3 consisted of teeth with mesio-occlusal-distal (MOD) onlay prepared with hybrid ceramics and pulp chamber filled with flowable, light-cured, radiopaque resin composite. Group 4 consisted of teeth with MOD onlay and pulp chamber filled with fiber-reinforced composite. Group 5 consisted of teeth with MOD inlay and pulp chamber filled with flowable, light-cured, radiopaque resin composite. Group 6 consisted of teeth with MOD inlay and pulp chamber filled with fiber-reinforced composite. Inlay, onlay, and endocrowns were prepared with computer-aided design (CAD) and computer-aided machine (CAM) using hybrid ceramics. Universal testing machine was used for the measurement of the fracture resistance of each specimen. Inferential statistics were performed by applying Fisher's exact test and chi-square test. Results: Fracture strength was found to be maximum in the intact teeth group followed by the endocrown. The fracture strength was minimum in the inlay group. The fracture strength was intermediate in the onlay groups. Conclusion: Endocrown showed maximum fracture resistance as compared to the inlay and onlay restorations. Clinical significance: Proper management of root canal-treated teeth is one of the greatest challenges for endodontists. It has been observed that tooth preparation design and the material used for the restoration of root canal-treated teeth play a vital role in the resistance against fracture in the teeth.