Effect of fiber post space irrigation with different peracetic acid formulations on the bond strength and penetration into the dentinal tubules of self-etching resin cement.

STATEMENT OF PROBLEM: The post space must be irrigated with solutions that do not interfere with the bond strength and enhance penetration into the dentinal tubules of self-etching resin cement. Which solution is best is unclear. Peracetic acid with different formulations appears to be a good option. PURPOSE: The purpose of this in vitro study was to evaluate the effect of irrigating the fiber post space by using 1% peracetic acid (PA) at low (LH) or high (HH) hydrogen peroxide concentration on the bond strength and penetration into the dentinal tubules of RelyX U200 self-etching resin cement. MATERIAL AND METHODS: After intraroot preparation for fiber posts in 60 endodontically treated teeth, the specimens were divided into 4 groups (n=15) according to the irrigation protocol: CG (control), distilled water; NA (NaOCl), 2.5% sodium hypochlorite; LHPA, PA with a low concentration of hydrogen peroxide; and HHPA, PA with a high concentration of hydrogen peroxide. The fiber posts were then cemented with self-etching resin cement labeled with rhodamine. Cross sections of the thirds were obtained by confocal scanning microscopy and submitted to the push-out and cement penetration tests. The data obtained in the push-out tests were evaluated by using ANOVA and the Tukey post hoc test, and those data obtained in the confocal screening were evaluated by using the Kruskal-Wallis and Dunn (Bonferroni correction) tests (α=.05). RESULTS: Bond strength values in the cervical third of the CG were higher than those in NA (P=.035) but similar to those of the other groups (P=.05). In the other thirds, CG and LHPA values were similar to one another (P=.05) but higher than those of NA and HHPA (P<.001). The penetration rate assessed by confocal scanning microscopy revealed similar results in the cervical third for all groups (P=.075), except for NA which provided the lowest penetration. In the remaining thirds, CG and LHPA provided the highest penetration rate (P=.015). CONCLUSIONS: The LHPA group had no negative effects on the bond strength and penetration into the dentinal tubules of the self-etching resin cement.

Irrigação ultrassônica passiva proporciona menor incidência de debris após preparo do espaço para o pino / Passive ultrasonic irrigation provides less debris after post space preparation

Objetivo: esse estudo avaliou a incidência de resíduos (debris) na dentina, no espaço preparado para pino de fibra, submetida a um dos seguintes protocolos de irrigação: água destilada (AD); hipoclorito de sódio a 2,5% (HS); hipoclorito de sódio a 2,5% mais EDTA a 17% (HSE); hipoclorito de sódio a 2,5% agitado com irrigação ultrassônica passiva (HSUS). Métodos: os canais radiculares de quarenta incisivos bovinos, com comprimento radicular de 17,0 mm, foram obturados pela técnica do cone único. Após sete dias, um espaço para o pino de fibra foi preparado com brocas de Largo #1 e #2 e broca DC2 (White Post; FGM). Os espécimes foram aleatoriamente distribuídos em quatro grupos (n = 10), de acordo com o protocolo de irrigação usado: AD; HS, HSE ou HSUS. As raízes foram clivadas longitudinalmente e obtidas imagens, em microscopia eletrônica de varredura (500X), da superfície dentinária dos segmentos radiculares cervical e apical do espaço preparado para pino de fibra. Escores foram atribuídos de acordo com a presença de debris. Resultados: no segmento cervical, HSE e HSUS apresentaram menor incidência de debris do que AD e HS (p < 0,05). No segmento apical, HSUS proporcionou a menor incidência de debris na dentina radicular (p < 0,05). Não houve diferença entre os demais protocolos de irrigação, tanto no segmento cervical quanto no apical (p > 0,05). Conclusões: o protocolo HSUS proporcionou menor incidência de debris sobre a superfície dentinária do espaço preparado para pino de fibra (AU).

Objective: The present study evaluated the residues (debris) incidence in dentin fiber post space submitted to irrigation protocols using distilled water (DW), 2.5% sodium hypochlorite (HS), 2.5 % sodium hypochlorite and 17% EDTA (HSE), or 2.5% sodium hypochlorite energized bypassive ultrasonic irrigation (HSUS). Methods: Forty bovine incisors root canals with standardized root length (17.0mm) were obturated using single cone technique and epoxyresin sealer. After 7 days, the fiber post space was prepared using # 1 and # 2 Largo burs, and DC2 (White Post; FGM).The specimens were randomly divided into four groups (n= 10), according to the irrigation protocol: AD; HS, HSE or HSUS. After 48 hours, the roots were sectioned. Cervical and apical segment images were obtained using scanning electron microscopy (500X). Scores were assessed according to debris presence. Results: In cervical segment, HSE and HSUS presented debris incidence lower than DW and HS (P <0.05). DW and HS or HSE and HSUS were similar to each other (P > 0.05). Conclusions: HSUS provided the lower debris incidence in dentin surface of the fiber post space (P < 0.05) (AU).

Effects of photodynamic therapy on the adhesive interface using two fiber posts cementation systems.

INTRODUCTION: Photodynamic therapy (PDT) can be employed for prosthetic space decontamination; however, its effects on adhesion of glass-fiber posts cementation systems are still unclear. PURPOSE: The aim of this study was to evaluate the effects of photodynamic therapy (PDT) on the adhesive interface between the dentin and different glass-fiber post cementation systems using a self-adhesive resin cement (RelyX U200) or a glass ionomer cement (Gold Label 1). METHOD: Forty human canine roots were endodontically-treated and prepared for fiber post. The roots were divided into four groups (n = 10), according to the PDT use and cementation protocol, as follow: G1- RelyX U200; G2: Gold Label 1; G3: PDT + RelyX U200; and G4: PDT + Gold Label 1. Afterwards, the roots were cross-sectioned and specimens from the cervical, middle and apical thirds of the post space were obtained and submitted to the push-out test. After that, the dentinal penetrability of the cementation protocol was assessed using laser confocal microscopy. CURRENT RESULTS: No significant differences were found in the bond strength values among the groups in all thirds (P > 0.05). G2 and G4 presented lower dentinal penetrability than the other groups, only in the cervical third (P < 0.05). CONCLUSION: Photodynamic therapy didn't present effects on the bonding interface between root dentin and fiber post cementation systems in both RelyX U200 and Gold Label 1, which were similar to each other.

Effects of different peracetic acid formulations on post space radicular dentin.

STATEMENT OF PROBLEM: The optimal irrigating solution with antimicrobial and dentin cleansing properties for post space preparation for fiber posts is unclear. Peracetic acid is one option but is available in various chemical formulations that require evaluation. PURPOSE: The purpose of this in vitro study was to evaluate dentin surface cleanliness based on the presence of a smear layer and the number of open dentin tubules. It also investigates the chemical composition of residues after canal irrigation with a 1% peracetic acid solution (PA) at low or high concentration of hydrogen peroxide during the preparation of intracanal fiber posts. MATERIAL AND METHODS: After filling the root canals of 40 mandibular incisors, a rotary instrument was used for intracanal preparation to place fiber posts. The teeth were divided into 4 groups (n=10) according to the post space irrigation protocol as follows: CG (control): distilled water; NA (NaOCl): 2.5% sodium hypochlorite; LH: PA with low concentration of hydrogen peroxide; and HH: PA with high concentrations of hydrogen peroxide. After irrigation, the teeth were sectioned, and the intracanal dentin surface was subjected to analysis using energy dispersive spectroscopy to evaluate chemical composition and to scanning electron microscopy (×500) to evaluate the presence of the smear layer. The number of open dentin tubules was measured by scanning electron microscopy analysis (×2000) using photo-editing software. ANOVA and the Tukey test (α=.05) were used to evaluate the data, except for the presence of a smear layer, for which the Kruskal-Wallis and Dunn tests were used (α=.05). RESULTS: The highest concentrations of oxygen in the dentin residues were detected in LH and HH (P<.05); CG and NA showed similar oxygen concentrations (P>.05). NA had a higher concentration of chlorine (P<.05), whereas LH had a lower amount of smear layer and a larger number of open dentin tubules than the other groups (P<.05). These were equivalent to each other (P>.05), except for HH, which also had a larger number of open dentin tubules than CG and NA (P<.05). CONCLUSIONS: PA 1% with a low concentration of hydrogen peroxide yielded a lower amount of smear layer and a larger number of open dentin tubules in the dentin of the post space when compared with PA 1% with a high concentration of hydrogen peroxide, despite maintaining a similar oxygen concentration in these dentin residues.