Endodontically Treated Maxillary Premolars Restored with Glass Fiber Post under All Ceramic Crown

Glass fiber posts and core are increasingly used in order to restore severely damaged endodontically treated teeth and particularly maxillary premolars that are prone to fracture. Their low modulus of elasticity which is similar to that of dentin allows the post to absorb stress and prevent root fracture. In addition, the glass fiber posts provide a natural hue by integrally bonding to the composite, thereby improving the aesthetics without compromising much on the strength. Various factors are involved in the longevity of such treatment option, remaining tooth structure seems to be the most important. Key words: glass fiber posts, premolars, endodontically treated teeth, composite resin, fracture resistance, crown, ferrule, failure .

Effect of intracanal diode laser irradiation on fracture resistance of roots restored with CAD/CAM posts

Aim: To evaluate the fracture resistance of roots restored with CAD/CAM-fabricated posts, receiving or not intracanal laser treatment, compared with glass fiber posts under mechanical cycling. Methods: Twenty-seven endodontically treated, single-rooted teeth were divided into 3 groups: group 1 (control), prefabricated glass fiber posts relined with resin composite; group 2, CAD/CAM-fabricated intraradicular posts using Resin Nano Ceramic (RNC) blocks; and group 3, CAD/CAM-fabricated intraradicular posts using RNC blocks in canals irradiated with a 940-nm diode laser (100 mJ, 300-um optic fiber, coronal-apical and apical-coronal helical movements, speed of 2 mm/second, 4 times each canal). After cementation of the coping, cyclic loading was applied at an angle of 135° to the long axis of the root, with a pulse load of 130 N, frequency of 2.2 Hz, and 150,000 pulses on the crown at a point located 2 mm below the incisal edge on the lingual aspect of the specimen. Every 50,000 cycles, the specimens were evaluated for root fracture occurring below or above the simulated bone crest. Results were analyzed by one-way ANOVA followed by Tukey’s test (p<0.05). Results: Group 1 was the least resistant, while groups 2 and 3 were the most resistant. Group 1 differed significantly from groups 2 and 3 (p<0.01), but there was no difference between groups 2 and 3 (p<0.01). Conclusion: Treatment of the intracanal surface with diode laser had no influence on fracture resistance of roots restored with CAD/CAM-fabricated posts, but a longer cycling time is required to evaluate the real benefits of diode laser irradiation.

CAD/CAM Milled Glass Fiber Posts: Adaptation and Mechanical Behavior in Flared Root Canals

SUMMARY This study aimed to evaluate the cementation and mechanical behavior of flared root canals restored with CAD/CAM milled glass fiber post-and-core systems. Sixty-six endodontically treated human canines with a flared root canal were divided into three different groups according to the type of post: GPF received prefabricated posts; GREL received relined glass fiber posts, and GMILLED received CAD/CAM milled glass fiber posts. Cementation was performed with self-adhesive resin cement. The samples were submitted to x-ray microcomputed tomography analysis for the analysis of voids and gaps. The roots were sectioned and submitted to the push-out bond strength test. The load-to-fracture was evaluated in post-and-core systems. GMILLED presented lower void and lower gap volumes when compared to GPF and GREL. On the load-to-fracture test, GREL presented statistically significant higher values than GMILLED. GPF values had no statistically significant difference from the two other groups. On the push-out bond strength test, GPF presented statistically significant lower values when compared to GREL and GMILLED. The most common failure pattern was between dentin and cement in all groups. CAD/CAM milled glass fiber post-and-core systems presented an enhanced adaptation of glass fiber posts to flared root canal systems. Their results were comparable to relined posts in bond strength, while load-to-fracture-results for GMILLED were lower than those for GPF.

Better Glass-fiber Post Preservation in Teeth with Ferrule When Subjected to Chewing

SUMMARY Objectives: To evaluate the influence of ferrule effect and mechanical fatigue aging on glass-fiber post push-out bond strength (PBS) to root-canal dentin at different root thirds of premolars. Methods and Materials: Thirty-two sound maxillary premolar teeth were collected, and randomly assigned to two experimental groups (n=16): ‘Remaining Dentin Ferrule’ (RDF) = coronal crown cut 2.0 mm above the cemento-enamel junction (CEJ); ‘Without Dentin Ferrule’ (WDF) = coronal crown cut at the cemento-enamel junction. Teeth were endodontically treated, post spaces were prepared up to 10.0-mm depth from CEJ, and glass-fiber posts were cemented using a dual-cure self-adhesive composite cement. Standardized cores were built using a light-cure composite, upon which tooth cores were prepared using a 1.5-mm taper ogival-end diamond bur. Crowns were handmade using self-cure acrylic resin and cemented using the aforementioned composite cement. Half of the specimens were subjected to 1,200,000 cycles of mechanical fatigue in a chewing simulator (F = ‘Fatigue’), while the other half were stored in distilled water at 37°C for 1 week (C = ‘Control’). All specimens were horizontally sectioned into 1.0-mm thick slices prior to PBS test; the failure modes were assessed using stereomicroscopy and scanning electron microscopy (SEM). Data were analyzed for each root third using two-way analysis of variance (ANOVA) followed by Tukey HSD post-hoc test; frequency distribution was compared by Chi-square test (α=0.05) and post-hoc comparisons with Bonferroni. Results: The mean PBS in MPa (SD) were = RDF_F = 10.4 (2.9); WDF_F = 6.9 (1.7); RDF_C = 14.5 (2.7); WDF_C = 14.2 (2.9). Similar PBS were found for the root thirds. For all root thirds, significant differences were found for both the factors Dentin Ferrule and Fatigue, and their interaction (p&lt;0.05). The lowest PBS was found for specimens without dentin ferrule subjected to chewing fatigue (p&lt;0.001). Most failures occurred at the composite cement/dentin interface, followed by mixed and composite cement/glass-fiber post interfacial failures. There was a significant increase in mixed failures for the WDF_F group (p&lt;0.001). Conclusion: Absence of 2.0-mm remaining dentin ferrule in premolars resulted in a higher decrease of the glass-fiber posts’ PBS to dentin after mechanical fatigue, irrespective of root third.

Avaliação dos tratamentos de superfície na resistência de união entre dois pinos de fibra de vidro e uma resina composta

Introduction: The aim of this study was to evaluate the influence of different surface treatment methods on glass-fiber posts relative to their bond strength with the composite resin and to evaluate the types of failures that occurred. Materials and Methods: Thirty-six posts from WhitepostDC (FG group) and Exacto Conics (AG group) were used, divided into: Control FG-1 and AG-1 groups – application of silane, according to manufacturers’ specifications; FG-2 and AG-2 groups – conditioning with 10% hydrogen peroxide and silanization; FG-3 and AG-3 groups – aluminum oxide blasting for 10 seconds and silaniza-tion. The composite resin was added in 2-mm increments, each increment was photopolymerized for 40 seconds, until the entire length of the matrix was filled. Then, the assembly (fiber post and composite resin) was sectioned into three portions (cervical, middle and apical) (n = 18). Samples were submitted to the bond strength analysis by a push-out test in a Universal Testing Machine and the failure types were evaluated with a 30 × magnification with an optical micro-scope. Data were submitted to the analysis of variance, the Tukey test, and the chi-square test with a 5% significance level. Results: For AG groups, the treatment with silane (23.10 MPa) resulted in statistically greater bond strength than the treatments with peroxide (17.19 MPa) and blasting (16.28 MPa). It was found that the bond strength was statistically higher in the middle third (21.16 MPa) than in the apical third (12.55 MPa) for the peroxide treatment. The mixed-type failure had the highest prevalence (57.01%). Conclusion: Silane treatment showed statistically greater bond strength values, when the Angelus brand was tested.

Stress Concentration of Endodontically Treated Molars Restored with Transfixed Glass Fiber Post: 3D-Finite Element Analysis

The loss of dental structure caused by endodontic treatment is responsible for a decrease in tooth resistance, which increases susceptibility to fracture. Therefore, it is important that minimally invasive treatments be performed to preserve the dental structure and increase the resistance to fracture of endodontically treated posterior teeth. To evaluate under axial loads, using the finite element method, the stress distribution in endodontically treated molars restored with both transfixed or vertical glass fiber posts (GFP) and resin composite. An endodontically treated molar 3D-model was analyzed using finite element analyses under four different conditions, class II resin composite (G1, control model), vertical glass fiber post (G2), transfixed glass fiber posts (G3) and vertical and transfixed glass fiber posts (G4). Ideal contacts were considered between restoration/resin composite and resin composite/tooth. An axial load (300 N) was applied to the occlusal surface. The resulting tensile stresses were calculated for the enamel and dentin tissue from five different viewports (occlusal, buccal, palatal, mesial and distal views). According to the stress maps, similar stress trends were observed, regardless of the glass fiber post treatment. In addition, for the G1 model (without GFP), a high-stress magnitude can be noticed in the proximal faces of enamel (7.7 to 14 MPa) and dentin (2.1 to 3.3 MPa) tissue. The use of transfixed glass fiber post is not indicated to reduce the stresses, under axial loads, in both enamel and dentin tissue in endodontically treated molar with a class II cavity.

Post-retained Restorations: A Cost-minimization Analysis Nested in a Randomized Clinical Trial

SUMMARY Objectives: The aim of this study was to assess four post-retained restorative strategies for endodontically treated teeth using cost-minimization analysis. Methods and Materials: The cost-minimization analysis was based on primary data from a randomized clinical trial and followed the Consolidated Health Economic Evaluation Reporting Standards (CHEERS) guidelines. Two hundred twenty-five teeth (141 patients) restored using four strategies—teeth with ferrules+ restored with either glass fiber posts or direct composite or crowns, and teeth without ferrules- restored with either glass fiber or cast metal posts with crowns—were evaluated annually between 2009 and 2018. Initial costs and incremental costs per year were calculated. Survival curves were created using the Kaplan-Meier method and log-rank test. Kruskal-Wallis analysis was followed by Dunn’s test, which was used to compare restorative treatments, with a significance level of 5%. Results: Initial costs were greater for cast metal posts without crowns (US$153.14). Glass fiber posts with composite (US$27.11) were least costly; the most failures occurred in this group, but they were primarily repairable restoration fractures. The number of extractions, and thus cost, was greater for glass fiber posts with crowns. The mean annual cost was significantly lower for teeth restored with composite (p&lt;0.001). Ferrule presence did not significantly impact annual costs. Conclusions: The use of glass fiber posts and direct composite incurred significantly lower annual costs than did other alternatives involving crowns or metal posts.