Endodontically-treated Maxillary Premolars Research Articles

Comparison of Fracture Resistance among Different Post Placement Strategies and Core Buildup Materials in Endodontically Treated Maxillary Premolars: An In Vitro Study

Comparison of Fracture Resistance among Different Post Placement Strategies and Core Buildup Materials in Endodontically Treated Maxillary Premolars: An In Vitro Study

Evaluation of Fracture Resistance of Endodontically Treated Maxillary Premolars Restored with Different Restorative Materials - An In Vitro Study

Aim: In this study was evaluated the fracture resistance of endodontically treated maxillary premolars restored with different restorative materials. Methods: Sixty maxillary premolars were submitted to the same mesio-occlusal-distal cavity preparation, endodontic treatment and divided into 5 groups (n = 10): Coltosol Group – GCO restored with calcium silicate material; Glass Ionomer Cement Group – GGIC, restored with Maxxion R; Modified Glass Ionomer Cement – GMGIC, restored with Gold Label 2; Composite Group - GC, restored with Z100, and the positive control group (GP) - left unrestored. One group remained intact (n=10) serving as negative control (GN). Samples were subjected to fracture resistance testing by the universal testing machine until fracture occurred and was registered in newtons (N). Fracture pattern was assessed and described as favorable or unfavorable. The results were statistically analyzed by 1-way analysis of variance and the post hoc Tukey test with significant statistical difference at P < 0.05. Results: Higher fracture resistance results were found for GC (1,128.35 ± 249.17), GMGIC (1,250.77 ± 173.29), and GN (1,277.22 ± 433.44) (P < .05). More favorable fractures were observed in the GCO (6), GC (7), and GN (7) (P < .05). Conclusion: Teeth restored with composite and modified GIC presented the same resistance as intact teeth. Teeth restored with Coltosol and GGIC presented similar resistance to unrestored teeth.

Fracture Resistance of Endodontically Treated Maxillary Premolars Restored With Different Methods.

The purpose of this in vitro study was to evaluate the resistance and patterns of fracture of endodontically treated maxillary premolars (ETPs) restored with different methods. Mesio-occluso-distal cavities were prepared in 50 extracted caries-free human maxillary premolars after endodontic treatment. The teeth were divided into five groups (n=10), according to the restorative method. G1: intact teeth (control group); G2: conventional composite resin; G3: conventional composite resin with a horizontal glass fiber post inserted between buccal and palatal walls; G4: bulk-fill flowable and bulk-fill restorative composites; and G5: ceramic inlay. For direct restorations, Filtek Z350 XT, Filtek Bulk Fill Flowable Restorative, and Filtek Bulk Fill Posterior Restorative were used. Indirect restorations were fabricated from a pressable lithium disilicate glass-ceramic (IPS e-max Press) and adhesively cemented (RelyX Ultimate). All specimens were subjected to thermocycling (5°C to 55°C/5000 cycles) and additionally submitted to cyclic loading 50,000 times in an Electro-Mechanical Fatigue Machine. Next, the specimens were subjected to a compressive load at a crosshead speed of 1 mm/min until fracture. The fractured specimens were analyzed to determine the fracture pattern using a stereomicroscope, and then representative specimens were carbon coated to allow for the studying of the fracture surface under scanning electron microscopy. One-way analysis of variance (ANOVA) was used to compare fracture resistance of the groups. The results of fracture patterns were submitted to the Fisher exact test (α=0.05). All specimens survived fatigue. Mean (standard deviation) failure loads (N) for groups were as follows: G1: 949.6 (331.5); G2: 999.6 (352.5); G3: 934.5 (233.6); G4: 771.0 (147.4); and G5: 856.7 (237.5). The lowest fracture resistance was recorded for G4, and the highest ones were recorded for G2, followed by that of G1 and G3. One-way ANOVA did not reveal significant differences between groups ( p>0.05). The highest repairable fracture rates were observed in G1 (100%) and G3 (80%). ETPs restored with conventional composite resin with or without horizontal fiber post, bulk-fill composite, and ceramic inlay showed fracture resistance similar to that of sound teeth. Conventional composite resin restorations exhibited the highest prevalence of unrepairable fractures, and the insertion of a horizontal fiber post decreased this prevalence. Intact teeth showed 100% of repairable fractures. It is difficult to extrapolate the results directly to a clinical situation due to the limitations of this study.

Effects of different cusp coverage restorations on the fracture resistance of endodontically treated maxillary premolars

Statement of problemCusp coverage restorations for the restoration of endodontically treated teeth represent a conservative approach in terms of function and esthetics. However, limited scientific data are available regarding the optimum reduction design and thicknesses. PurposeThe purpose of this in vitro study was to evaluate the fracture resistance and fracture patterns of cusp coverage restorations with different cusp reduction designs and reduction thicknesses on endodontically treated maxillary premolars (ETMPs) with mesio-occluso-distal (MOD) cavities. Material and methodsOne hundred sixty-five extracted intact human maxillary premolars were divided into 11 groups: G1-10 (test groups) and G11 (intact group). In the test groups, all of the teeth were restored with composite resin after canal treatments with MOD cavities. However, the cusps of the G1-9 teeth were reduced with combinations of different thicknesses (1.5, 2.5, and 3.5 mm) and designs (beveled, horizontal, and anatomic). The specimens were subjected to 105 cycles of 50 N mechanical loading. Next, the specimens were subjected to a compressive load at a crosshead speed of 0.5 mm/min until fracture. The fractured specimens were analyzed to determine the fracture pattern. Two-way ANOVA followed by the Fisher least significant difference (LSD) test was used to analyze the interaction between groups. ResultsThe fracture resistance values increased with increases in the cusp reductions. The fracture resistance values of the G6 (2.5 mm, anatomic) and G9 (3.5 mm, anatomic) groups were significantly greater than that of the MOD group. However, the G6, G8 (3.5 mm, horizontal), and G9 groups were comparable with G11. The highest restorable fracture rates were observed in G6 and G9. ConclusionsCusp reduction design and thickness influenced the fracture resistance and fracture patterns of cusp coverage restorations of ETMPs with MOD cavities. The teeth restored with anatomic cusp reduction designs with reduction thicknesses of at least 2.5 mm exhibited greater fracture resistance and more frequent restorable fractures.

Fracture Resistance of Endodontically Treated Maxillary Premolars Restored by Various Direct Filling Materials: An In Vitro Study.

The aim of this study is to compare the effect of various restorative materials on fracture resistance in maxillary premolars. Premolars (n = 64) with no restorations or cracks were selected. MOD cavities were prepared considering the buccolingual width to be equal to half of the intercuspal distance. The specimens were randomly divided into 8 groups, 8 specimens each: group A intact teeth, group B unfilled cavity, group C composite made by oblique layering technique, group D composite with 2 mm cusp coverage, group E bulk-filled posterior composite, group F glass-ionomer, group G amalgam, and group H composite with proximal boxes. The specimens were subjected to an axial compression load with the mean values of fracture resistance in group A: 1289 N, group B: 181.75 N, group C: 445.38 N, group D: 645.88 N, group E: 355.13 N, group F: 352.00 N, group G: 191.38 N, and group H: 572.00 N. There was no significant difference between groups B and G, between C and D, E, and F, and between group D and H. All other measurements were statistically significant. We conclude that composite restoration with cusp coverage is the most ideal nonprosthetic solution for endodontically treated teeth. Cusp coverage increases the fracture resistance compared to the conventional cavity design.

Effect of remaining tooth structure on the fracture resistance of endodontically-treated maxillary premolars: An in vitro study

Statement of problemAssessing the quantity and distribution of residual coronal dentin is important in deciding the restorability of endodontically treated teeth. PurposeThe purpose of this in vitro study was to investigate the relationship between the cross-sectional area and location of remaining coronal tooth structure and the fracture resistance of restored teeth after endodontic treatment. Material and methodsFifty-five extracted maxillary premolars received endodontic treatment and crown preparations. The teeth were assigned to 11 groups of 5 teeth according to the number and the location of missing axial walls. Impressions of the prepared teeth were made to fabricate dies. Each die was sectioned 1 mm above the finish line, and the dentin surface area was measured. All teeth were restored with composite resin cores and cast metal crowns. The specimens were thermocycled between 5°C and 55°C for 500 cycles before loading until failure with a universal testing machine. The results were analyzed with 1-way ANOVA and post hoc comparisons. ResultsSpecimens with all axial walls intact around the access cavity had the highest mean fracture strength (1380.5 ±393.9 N). Groups with the palatal and 1 or 2 proximal walls missing showed the lowest mean failure loads (398.4 N ±149.5 N and 344.7 N ±91.2 N). The correlation between the surface area and the fracture resistance was 0.72 ConclusionsFor restored endodontically treated maxillary premolars, a positive linear relationship was found between the remaining coronal dentin surface area and fracture strength. Residual dentin location influences fracture resistance.

Finite Element Analysis of the Endodontically-treated Maxillary Premolars restored with Composite Resin along with Glass Fiber Insertion in Various Positions.

This study evaluated the effect of three methods of glass fiber insertion on stress distribution pattern and cusp movement of the root-filled maxillary premolars using finite element method (FEM) analysis. A three-dimensional (3 D) FEM model of a sound upper premolar tooth and four models of root-filled upper premolars with mesiocclusodistal (MOD) cavities were molded and restored with: (1) Composite resin only (NF); (2) Composite resin along with a ribbon of glass fiber placed in the occlusal third (OF); (3) Composite resin along with a ribbon of glass fiber placed circumferentially in the cervical third (CF), and (4) Composite resin along with occlusal and circumferential fibers (OCF). A static vertical load was applied to calculate the stress distributions. Structural analysis program by Solidworks were used for FEM analysis. Von-Mises stress values and cusp movements induced by occlusal loading were evaluated. Maximum Von-Mises stress of enamel occurred in sound tooth, followed by NF, CF, OF and OCF. Maximum Von-Mises stress of dentin occurred in sound tooth, followed by OF, OCF, CF and NF. Stress distribution patterns of OF and OCF were similar. Maximum overall stress values were concentrated in NF. Although stress distribution patterns of NF and CF were found as similar, CF showed lower stress values. Palatal cusp movement was more than buccal cusp in all of the models. The results of our study indicated that while the circumferential fiber had little effect on overall stress concentration, it provided a more favorable stress distribution pattern in cervical region. The occlusal fiber reduced the average stress in the entire structure but did not reduce cuspal movement. Incorporating glass fiber in composite restorations may alter the stress state within the structure depending on fiber position.

Fracture Resistance of Endodontically-treated Maxillary Premolars Restored with Composite Resin along with Glass Fiber Insertion in Different Positions.

Background and aims The aim was to evaluate the effect of three methods of fiber insertion on fracture resistance of root-filled maxillary premolars in vitro. Materials and methods Sixty extracted human maxillary premolars received endodontic treatment followed by preparation of mesioocclusodistal (MOD) cavities, with gingival cavosurface margin 1.5 mm coronal to the cementoenamel junction (CEJ). Subsequently, the samples were randomly divided into four groups: no-fiber group; occlusal fiber group (fiber was placed in the occlusal third); circumferential fiber group (fiber was placed circumferentially in the cervical third); and dual-fiber group (occlusal and circumferential fibers). Subsequent to restoring with composite resin and thermocycling, a compressive force was applied until fracture. Data was analyzed using one-way ANOVA and Tukey test at significance levels of P < 0.05 and P < 0.02, respectively. Results Fiber placement significantly increased fracture resistance. Fracture resistance in the dual-fiber group was significantly higher than that in the circumferential fiber group (P < 0.007); however, there were no significant differences between the dual-fiber and occlusal fiber groups (P = 0.706). The highest favorable fracture rate was observed in the circumferential fiber group (60%). Conclusion Composite resin restoration along with glass fiber in the occlusal and gingival thirds can be an acceptable treatment option for restoring root-filled upper premolars.

The Effect of Composite Fiber Insertion along with Lowshrinking Composite Resin on Cuspal Deflection of Root-filled Maxillary Premolars

The aim of the present study was to evaluate the effect of three methods of composite fiber placement along with siloranebased composite resin on cuspal deflection and fracture strength of root-filled maxillary premolars. Mesio-occluso-distal cavities were prepared in 60 extracted premolars subsequent to endodontic treatment. The remaining thickness of buccal and lingual walls at height of contour was 2.5 ± 0.2 mm and the gingival cavosurface margin was 1.5 mm coronal to cementoenamel junction. Subsequent to measurement of primary intercuspal distances, the teeth were randomly divided into four groups. In group 1, the cavities were only filled with Filtek Silorane composite resin. In the other three groups, preimpregnated glass fibers were placed at gingival, middle and occlusal thirds respectively, and the cavities were restored similar to the group 1. Cuspal deflection was recorded in micrometer using a stereomicroscope. Fracture strength of the samples was measured in Newton subsequent to thermocycling. Data was analyzed using Kruskal-Wallis, Mann-Whitney U, one-way ANOVA and post-hoc Tukey tests at a significance level of p < 0.05. The highest cuspal deflection was recorded in the group 1, and the difference between group 1 and other groups was significant (p < 0.001). Fracture resistance in group 4 was significantly higher than that in other groups (p < 0.001). In restoring root-filled premolars with siloranebased composite resins, cuspal deflection decreased with the use of preimpregnated glass fibers. Using preimpregnated glass fibers along with silorane-based composite resin may lead to better results in cuspal deflection and fracture resistance of endodonticallytreated maxillary premolars.

Three-year clinical evaluation of cuspal coverage with combined composite–amalgam in endodontically-treated maxillary premolars

The authors of this audit suggest that this 'one-appointment combined restoration technique ... yielded clinically acceptable results...'.

Three-year Clinical Evaluation of Cuspal Coverage with Combined Composite–Amalgam in Endodontically-treated Maxillary Premolars

This clinical study evaluated the clinical performance of cuspal coverage with combined composite-amalgam restorations in endodontically-treated maxillary premolars over a three-year period. Thirty-six maxillary premolars, each with a Class II cavity in 36 patients ranging in age between 28 and 52 years, were selected after endodontic treatment. After reduction of the buccal and palatal cusps, internal coverage and veneering of the reduced buccal cusp was performed with composite. The remaining cavity and reduced palatal cusp were restored with high-copper amalgam. The restorations were evaluated at baseline and in one-, two- and three-year recalls with USPHS criteria. Changes in characteristics of the restorations were analyzed with the Cochran Q-test at a significance level of p < 0.05. Most of the restorations received an overall score of alpha, except two restorations, which showed a slight discrepancy at the composite-amalgam interface after one year (p > 0.05). Four restorations exhibited slight discoloration of the composite veneering after three years (p < 0.05). No restoration exhibited fracture after three years. It was concluded that combined composite-amalgam cusp coverage of endodontically-treated maxillary premolars showed acceptable clinical performance after three years.

Effect of Fiber Post and Cusp Coverage on Fracture Resistance of Endodontically Treated Maxillary Premolars Directly Restored with Composite Resin

IntroductionThere are different reinforcement methods in restoring root-filled teeth. The aim of this in vitro study was to evaluate the effect of fiber post and cusp coverage on fracture resistance of endodontically treated maxillary premolars directly restored with composite resin. MethodsSeventy-five maxillary premolars were divided into 5 groups (n = 15). Except for the control group (intact teeth), in other groups mesio-occlusodistal (MOD) cavities were prepared after endodontic treatment. In the groups with cusp coverage, both buccal and lingual cusps were reduced up to 2 mm. Then specimens in the experimental groups were prepared as follows: composite resin restoration without post and cusp capping, composite resin restoration without post but with cusp capping, composite resin restoration with post but without cusp capping, and composite resin restoration with post and cusp capping. After finishing and polishing, the specimens were stored in distilled water at 37°C for a week. Subsequent to thermocycling and exertion of compressive forces parallel to the long axes of the teeth at a strain rate of 2 mm/min, data were analyzed by using one-way analysis of variance and χ2 test. ResultsThere were no significant differences in fracture resistance between the groups (P = .057). However, χ2 test showed statistically significant differences between the groups in failure mode (P < .001). The highest number of favorable fractures was observed in the control group (intact teeth). ConclusionsRoot-filled maxillary premolars, restored with direct resin composite with or without fiber post and cusp capping, had similar fracture resistance under static loading.

Fracture Resistance and Stress Distribution in Endodontically Treated Maxillary Premolars Restored with Composite Resin

The aim of this study was to evaluate the effect of endodontic and restorative treatment on the fracture resistance of posterior teeth. 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). 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. 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.

In Vitro Fracture Resistance of Endodontically-treated Maxillary Premolars

Many endodontically-treated teeth require quick, simple, low-cost restorations. This study evaluated the effect of horizontal pins and flowable composites on the fracture resistance of endodontically-treated maxillary premolars directly restored with resin composite. In this in vitro study, 64 intact human maxillary premolars, extracted for orthodontic reasons, were randomly divided into four groups of 16. Standard access cavities were prepared in such a way that the buccal cusp had a buccolingual thickness of 3 mm measured at the height of contour. The palatal cusp was reduced to 1.5 mm coronal to CEJ. The specimens were prepared as follows: Group 1: resin composite restoration without horizontal self-threading pins or flowable composite (control group). Group 2: resin composite restoration without horizontal self-threading pins but with a 2 mm thickness of the flowable composite. Group 3: resin composite restoration with two horizontal self-threading pins in the buccal cusp but without flowable composite. Group 4: resin composite restoration with two horizontal self-threading pins in the buccal cusp and flowable composite with a thickness of 2 mm. Subsequent to thermocycling, all specimens were loaded to failure. The data were analyzed using a two-factor ANOVA test (alpha = 0.05). The maximum mean of fracture resistance was in Group 1 (632.86 +/- 119.46 N), and the minimum value was related to Group 3 (533.49 +/- 168.07 N). There was not a statistically significant difference between the groups (p > 0.05). Neither horizontal pin placement nor flowable composite had a significant effect on increasing the fracture resistance of endodontically-treated maxillary premolars restored with composite.

Effect of Different All-Ceramic Crown System on Fracture Resistance and Failure Pattern of Endodontically Treated Maxillary Premolars Restored With and Without Glass Fiber Posts

Endodontically treated teeth are traditionally restored with a crown to prevent fracture. The aim of this study was to compare the fracture resistance and failure modes of endodontically treated maxillary premolars treated with or without a fiber post and restored with different types of crowns. Eighty human maxillary premolars were selected. After root canal treatment, the teeth were embedded in resin blocks and divided into four groups. Samples received MOD cavity preparations and were divided into two subgroups: with and without fiber posts and restored using porcelain fused to metal, lithium disilicate, fiber-reinforced composite, or zirconia crowns. The specimens were vertically loaded in the central fossa using a universal loading machine until failure, and the maximum breaking loads were recorded. Samples were perfused with Indian ink to highlight the fracture lines and the mode of failure that was classified as restorable or nonrestorable. Even without post, all crown designs resisted vertically applied forces beyond those that may be encountered in the mouth. Two-way analysis of variance revealed the use of a fiber post (p = 0.007) and the type of crown (p < 0.001) significantly affected the restorability of fractured teeth. The relationship between placing or not placing the post and the type of failure (restorable/nonrestorable) was found to be significant (chi(2) test, p = 0.002). Although post placement resulted in higher fracture resistance values, these were significant for Empress II crowns only. The results suggest that the posts could contribute to the reinforcement and strengthening of pulpless maxillary premolars. With respect to failure modes, placement of fiber posts improved the fracture from nonrestorable to restorable patterns. This study suggests that the placement of fiber posts is necessary to improve fracture resistance even under full-coverage crowns.