Root canal preparation in 3-rooted maxillary premolars through hand, rotary, and reciprocating techniques: a microcomputed tomography evaluation.

Endodontic management of 3-rooted maxillary premolars is a challenge due to their complex anatomy and narrow root canal walls. This study aimed to evaluate, by microcomputed tomography (µCT), the apical enlargement and centering ability promoted by hand, rotary, and reciprocating instrumentation in 3-rooted maxillary premolars. Eighteen teeth were divided into 3 groups (n = 6) according to the preparation technique: crown-down hand, rotary, and reciprocating instrumentation. Instruments with similar apical diameters were used (25 and 40 mm for buccal and palatal canals, respectively). Centering ability and canal enlargement were evaluated through the comparison of µCT images obtained before and after instrumentation. Distances of 0, 2, 4, and 6 mm from the apical stop were considered. Differences between canal areas before and after instrumentation were calculated. In addition, distances between the original canal center and the prepared canal center at the apical stop were measured in both the mesiodistal and buccopalatal directions. Significant differences in enlargement areas and centering ability among the techniques were determined using 2-way analysis of variance and Tukey post hoc test (P > 0.05). Root canal enlargement was similar for all techniques. Excessive enlargement was observed in only a few specimens, and root perforation did not occur. Some specimens presented untreated canal areas. In mesiobuccal and distobuccal roots, reciprocating instrumentation promoted more centered preparations than hand instrumentation when measured in the mesiodistal direction (P > 0.05). There were no other statistically significant differences. The results established that hand, rotary, and reciprocating techniques presented similar safety margins for instrumentation of the apical third of 3-rooted maxillary premolars. Reciprocating instrumentation presented some advantages over hand preparation regarding centering ability.

Influence of surfactants addition on the properties of calcium hypochlorite solutions.

OBJECTIVES: The aim of this study was to evaluate the influence of surfactants 0.2% or 0.1% cetrimide (Cet) or 0.008% benzalkonium chloride (BAK) on 2.5% calcium hypochlorite (Ca(OCl)2), and compare to sodium hypochlorite (NaOCl), regarding the properties of pH, free chlorine content, surface tension, contact angle, pulp dissolution and antimicrobial activity. MATERIAL AND METHODS: The pH and free chlorine content were evaluated by digital pHmeter and by titration, respectively. Surface tension was measured by the platinum ring technique with a Du Noüy tensiometer. The solution's contact angle in human dentin surfaces was checked by Drop Shape Analyzer software. Bovine pulps were used for pulp dissolution analysis and the dissolving capacity was expressed by percent weight loss. Antimicrobial activity over Enterococcus faecalis was evaluated by the agar diffusion method. RESULTS: Surfactants addition to Ca(OCl)2 and NaOCl did not alter the pH, free chlorine content and pulp dissolution properties. Ca(OCl)2 had the highest surface tension among all tested solutions. When surfactants were added to Ca(OCl)2 and NaOCl, there was a significant reduction of surface tension and contact angle values. The addition of 0.2% or 0.1% Cet enhanced antimicrobial activity of both Ca(OCl)2 and NaOCl. CONCLUSION: Surfactant addition to 2.5% Ca(OCl)2 has shown acceptable outcomes for pH, free chlorine content, surface tension, contact angle, pulp dissolution and antimicrobial activity. Furthermore, the addition of 0.2% Cet showed better results for all tested properties.

Cell Viability and Tissue Reaction of NeoMTA Plus: An In Vitro and In Vivo Study.

INTRODUCTION: The aim of this study was to evaluate the cell viability and tissue reaction of NeoMTA Plus (NMP; Avalon Biomed Inc, Houston, TX) compared with mineral trioxide aggregate (MTA; Angelus, Londrina, PR, Brazil) and Biodentine (BD; Septodont, Saint-Maur-de-Fossés, France). METHODS: Fibroblasts (3T3) were plated and exposed to 1% extract from the test material before and after setting. Cytotoxicity assessment was performed using the 3-(4,5-dimethyl-thiazoyl)-2,5-diphenyl-tetrazolium bromide and sulforhodamine B assays. In vivo evaluation consisted of polyethylene tube implantation of the materials in rat subcutaneous tissue. Histologic analysis occurred at 7, 30, and 90 days, scoring inflammatory events and collagen fiber formation. Analysis of variance and the Tukey and t tests were used for cytocompatibility assays, and the Kruskal-Wallis test followed by the Dunn test were used for biocompatibility assays (P ≤ .05). RESULTS: The materials in the cytotoxicity assays presented greater viability after setting (P ≤ .05). NMP and MTA presented higher viability than the control (Dulbecco modified Eagle medium) on the 3-(4,5-dimethyl-thiazoyl)-2,5-diphenyl-tetrazolium bromide assay before and after setting (P ≤ .05). The sulforhodamine B assay showed that MTA and BD presented less viability than NMP and the control, and NMP was similar to the control before setting. After setting, MTA and BD presented higher viability when compared with the control group (P ≤ .05), and NMP was similar to control. Inflammatory infiltrate reduction occurred throughout the test periods for all materials. At 7 days, neutrophils were present in BD (P ≤ .05), and granuloma and giant cells were present in BD and MTA. At 30 days, BD showed intense inflammatory infiltrates and a large number of macrophages when compared with NMP, MTA, and the control (P ≤ .05). At 90 days, BD presented a thick fiber layer compared with NMP (P ≤ .05). CONCLUSIONS: NMP showed similar biocompatible behavior to MTA and BD.

Efeito do hipoclorito de cálcio na resistência de adesão do cimento obturador AH Plus à dentina / Effect of calcium hypochlorite on the bond strength of the AH Plus sealer to dentin

Objetivo: avaliar o efeito do uso de hipoclorito de cálcio (Ca(OCl)2) como irrigante na resistência de adesão do cimento AH Plus (De Trey-Dentsply, Konstanz, Alemanha) à dentina pelo teste de micro push-out. Materiais e método: trinta e três dentes humanos monorradiculares foram seccionados transversalmente na junção amelocementária e divididos em três grupos: hipoclorito de sódio (NaOCl) 2,5%, hipoclorito de cálcio 2,5% e soro fisiológico. Os canais foram preparados, irrigados ao final com EDTA 17% e obturados com cones de guta percha e cimento AH Plus. Após armazenagem por 7 dias, em 100% de umidade e a 37°C, os dentes foram seccionados transversalmente ao longo do eixo da raiz. Foram obtidas três fatias de cada dente (n=33), que foram submetidas ao ensaio de push-out. O tipo de falha foi analisado por fractografia e classificado em falha adesiva, coesiva ou mista. Os valores de resistência de união foram analisados pelo teste de Kruskal-Wallis, com nível de significância de 95%. Resultados: o grupo Ca(OCl)2 2,5% apresentou a menor média de resistência de adesão, diferindo estatisticamente do NaOCl e do soro fisiológico (p<0,05). Não houve diferença estatística entre os grupos irrigados com soro e NaOCl (p>0,05). Conclusões: a falha predominante em todos os grupos foi a do tipo adesiva. O Ca(OCl)2 2,5% teve um efeito negativo sobre a força de adesão do AH Plus à dentina radicular quando comparado ao NaOCl 2,5%. (AU)

Objective: to evaluate the effect of calcium hypochlorite (Ca(OCl)2) as an irrigant on the bond strength of the AH Plus sealer (De Trey-Dentsply, Konstanz, Germany) to dentin, using the micro push-out test. Materials and method: thirty-three single-rooted human teeth were cross-sectioned on the cementoenamel junction and divided into three groups: 2.5% sodium hypochlorite (Na- OCl), 2.5% calcium hypochlorite, and saline solution. The canals were prepared, irrigated with 17% EDTA at the end, and filled with gutta-percha cones and AH Plus sealer. After being stored for seven days at 100% humidity and 37ºC, the teeth were cross-sectioned along the root axis. Three slices of each tooth (n=33) were obtained and subjected to the push-out test. Failure mode was analyzed by fractography and classified as adhesive, cohesive, or mixed. Bond strength values were analyzed by the Kruskall-Wallis test at 95% significance level. Results: the 2.5% Ca(OCl)2 group showed the lowest bond strength mean, differing statistically from 2.5% NaOCl and saline solution (p<0.05). There was no statistical difference between the groups irrigated with saline solution and NaOCl (p>0.05). Conclusion: the adhesive failure was predominant in all groups. The 2.5% Ca(OCl)2 had a negative effect on the bond strength of AH Plus to the root dentin when compared to 2.5% NaOCl. (AU)