Influence of endodontic sealer composition and time of fiber post cementation on sealer adhesiveness to bovine root dentin.

This study aimed to assess the influence of the type of endodontic sealer (salicylate resin-based sealer vs. two endodontic sealers) and the time of fiber post cementation after root filling on the post adhesion to bovine root dentin. Sixty bovine roots were assigned to six groups (n=10), considering an experimental design with two factors (factorial 3x2): endodontic sealer factor in three levels [epoxy resin-based sealer (AH Plus), eugenol-based sealer (Endofill), and salicylate resin-based sealer plus mineral trioxide aggregate - MTA (MTA Fillapex)] and time for post cementation factor in two levels (immediate post cementation or 15 days after root canal filling). After post cementation, 2-mm-thick slices were produced and submitted to push-out test. The failure modes were analyzed under a 40× stereomicroscope and scored as: adhesive at cement/dentin interface; adhesive at cement/post interface; cement cohesive; post cohesive; dentin cohesive; or mixed. Data were analyzed using two-way ANOVA and Tukey's post-hoc tests (α=0.05). When the fiber posts were cemented immediately after the root canal filling, the bond strengths were similar, independent of the endodontic sealer type. However, after 15 days, the epoxy resin-based sealer presented higher bond strength than the other sealers (p<0.05). Comparison between each sealer in different experimental times did not reveal any differences. The main failure type was adhesive at dentin/cement interface (89.4%). The time elapsed between the root canal filling and post cementation has no influence on post/root dentin adhesion. On the contrary, the type of endodontic sealer can influence the adhesion between fiber posts and root dentin.

Influence of Endodontic Sealer Composition and Time of Fiber Post Cementation on Sealer Adhesiveness to Bovine Root Dentin

This study aimed to assess the influence of the type of endodontic sealer (salicylate resin-based sealer vs. two endodontic sealers) and the time of fiber post cementation after root filling on the post adhesion to bovine root dentin. Sixty bovine roots were assigned to six groups (n=10), considering an experimental design with two factors (factorial 3x2): endodontic sealer factor in three levels [epoxy resin-based sealer (AH Plus), eugenol-based sealer (Endofill), and salicylate resin-based sealer plus mineral trioxide aggregate - MTA (MTA Fillapex)] and time for post cementation factor in two levels (immediate post cementation or 15 days after root canal filling). After post cementation, 2-mm-thick slices were produced and submitted to push-out test. The failure modes were analyzed under a 40× stereomicroscope and scored as: adhesive at cement/dentin interface; adhesive at cement/post interface; cement cohesive; post cohesive; dentin cohesive; or mixed. Data were analyzed using two-way ANOVA and Tukey's post-hoc tests (α=0.05). When the fiber posts were cemented immediately after the root canal filling, the bond strengths were similar, independent of the endodontic sealer type. However, after 15 days, the epoxy resin-based sealer presented higher bond strength than the other sealers (p<0.05). Comparison between each sealer in different experimental times did not reveal any differences. The main failure type was adhesive at dentin/cement interface (89.4%). The time elapsed between the root canal filling and post cementation has no influence on post/root dentin adhesion. On the contrary, the type of endodontic sealer can influence the adhesion between fiber posts and root dentin.

Este estudo objetivou avaliar a influência do tipo de cimento endodôntico (um cimento à base de resina de salicilato e dois cimentos endodônticos) e do tempo decorrido entre a obturação do conduto e a cimentação do pino de fibra na adesão de pinos de fibra à dentina radicular bovina. Sessenta dentes bovinos foram divididos em seis grupos (n=10), considerando um desenho experimental de dois fatores (3x2): cimento endodôntico em três níveis [à base de resina epóxica (AH Plus), eugenol (Endofill) e resina de salicilato e MTA (MTA Fillapex)] e o tempo para cimentação em dois níveis (cimentação imediata e 15 dias pós a obturação). Após cimentação do pino de fibra, fatias com 2 mm de espessura foram obtidas e submetidas ao teste de push-out. Os padrões de falha foram analisados em estereomicroscópio (40×) e classificados em: adesiva na interface cimento/dentina, adesiva cimento/pino, coesiva do cimento, coesiva do pino, coesiva da dentina e mista. Os dados foram analisados através dos testes de ANOVA a dois fatores e post hoc de Tukey (α=0,05). Quando os pinos de fibra foram cimentados imediatamente após a obturação dos condutos, a resistência adesiva foi similar, independentemente do tipo de cimento endodôntico. Entretanto, após 15 dias, os dentes obturados com cimento resinoso à base de resina epóxica apresentaram os maiores valores de resistência adesiva (p<0,05). Os valores de resistência adesiva do mesmo cimento nos diferentes tempos experimentais não foram alterados. O principal tipo de falha foi adesiva na interface cimento/dentina (89,4%). O tempo decorrido entre a obturação dos condutos e a cimentação do pino não influenciou a adesão do pino de fibra à dentina radicular. Por outro lado, o tipo de cimento endodôntico influencia a adesão entre dentina radicular e pinos de fibra.

Vertical root fractures and dentin defects: effects of root canal preparation, filling, and mechanical cycling.

INTRODUCTION: The aim of this study was to evaluate the ex vivo effects of root canal preparation, filling techniques, and mechanical cycling (MC) on the incidence of dentin defects and vertical root fractures (VRFs). METHODS: Seventy extracted single-rooted teeth were divided into 6 groups. The first 2 groups were the unprepared and unprepared/MC groups. The other groups were prepared by using Gates Glidden drills and ProTaper Universal files up to F3 and were grouped according to the following: prepared teeth and the absence of root canal filling, passive technique, lateral compaction, and Tagger's hybrid technique. All of the groups except the unprepared group were subjected to MC (1,000,000 cycles, 90 N, 4 Hz, 37°C). The roots were then sectioned horizontally at 3, 6, and 9 mm from the apex and observed under a ×10 stereomicroscope. The defects were categorized as no defect, vertical root fracture, and other defects. The differences between the groups were analyzed by using the Fisher exact and χ(2) tests. RESULTS: MC by itself did not influence the incidence of dentinal defects (P > .05, between the unprepared and unprepared/MC groups). The filled groups presented a similar incidence of other defects (P > .05), although VRFs were observed only when the MC was associated with pressure filling techniques (the lateral compaction and Tagger's hybrid groups). CONCLUSIONS: MC by itself did not induce VRF. When associated with apical pressure filling techniques, however, VRF occurred in 13.3% (lateral compaction) and 33.3% (Tagger's hybrid) of the cases.