Dynamic Cyclic Fatigue Resistance of Heat-treated Nickel Titanium Instruments in Reciprocating Motion.

OBJECTIVE: To compare the fatigue resistance of different heat-treated reciprocating instruments tested in a dynamic cyclic fatigue model. METHODS: Forty-eight new instruments were inspected under magnification and selected for this study, and then divided as follows (n=12): X1 Blue (MK Life, Porto Alegre, RS, Brazil), Pro-R (MK Life), Reciproc (VDW, Munich, Germany), and Reciproc Blue (VDW). Artificial canals presenting a curvature of 60° angle and 5 mm radius were milled in zirconia. The block containing the artificial canals was mounted in a container filled with water kept at 37°C. A specially designed device was used to perform controlled axial movements while the instruments were activated inside the canals. Time to failure was recorded in seconds, and fragment lengths were measured (mm). Data were analyzed statistically with the significance level set at 5% (One-Way ANOVA and Tukey test). RESULTS: Pro-R and Reciproc Blue instruments presented the highest fatigue resistance, being significantly different from the other tested files (p<0.05). Reciproc presented intermediate results, significantly different X1 Blue (p<0.05). The fractographic analysis showed typical features of cyclic fatigue for all instruments. CONCLUSION: Pro-R and Reciproc Blue instruments are more resistant to dynamic cyclic fatigue than the Reciproc and X1 Blue. (EEJ-2022-10-124).

Produtividade dos estudantes de Odontologia na clínica integrada em duas universidades do Sul do Brasil / Productividad de los estudiantes de Odontología en la clínica integrada en dos universidades del sur de Brasil / Productivity of dental students in integrated clinics attwo universities in Southern Brazil

Este estudo avaliou e comparou a produtividade clínica dos estudantes de Odontologia em duas instituições de ensino privadas, com diferentes tempos de experiência no modelo de clínica integrada, preconizado pelas Diretrizes Curriculares Nacionais (DCN). Asuniversidades utilizam o modelo de clínica integrada desde 2001 [A] e 2009 [B], com cursos de graduação de 5 anos e 4 anos, respectivamente. O estudo foi realizado no período de fevereiro a dezembro de 2019. Foram incluídos dados relativos a 205 estudantes (56 da universidade [A] e 149 da [B]) matriculados nas clínicas de baixa/média (n=99) e alta complexidades (n=106). Avaliou-se a quantidade de procedimentos realizados por nível de complexidade nas duas instituições. Os dados foram submetidos aos testes de Mann-Whitney e qui-quadrado (α=0,05). O número de procedimentos analisados foi de 9706, sendo 4693 na instituição [A] e 5013 na [B]. Nas duas instituições a quantidade de procedimentos curativos (54,8%) foi significativamente maior que a de procedimentos de diagnóstico e atenção à saúde (45,2%) (p<0,001). Nas clínicas de baixa/média complexidade foram observadas diferenças estatísticas na quantidade de procedimentos e/ou na quantidade de estudantes que não realizaram determinados procedimentos clínicos. Nas clínicas de alta complexidade foram observadas diferenças estatísticas entre as instituições na quantidade de procedimentos e/ou na quantidade de alunos que não realizaram determinados procedimentos específicos de Dentística, Cirurgia, Periodontia e Prótese. A instituição com maior tempo de experiência no modelo de clínica integrada apresentou melhores resultados nas especialidades de Dentística, Endodontia e Prótese (AU).

Este estudio evaluó y comparó la productividad clínica de estudiantes de odontología de dos instituciones de enseñanza privadas, con diferentes tiempos de experiencia en el modelo clínico integrado, recomendado por las Directrices Curriculares Nacionales (DCN). Las universidades han utilizado el modelo clínico integrado desde 2001 [A] y 2009 [B], con carreras de grado de 5 y 4 años, respectivamente. El estudio se realizó de febrero a diciembre de 2019. Se incluyeron datos de 205 estudiantes (56 de la universidad [A] y 149 de la [B]) matriculados en clínicas de baja/media (n=99) y alta complejidad (n=99) n=106). Se evaluó el número de procedimientos realizados por nivel de complejidad en ambas instituciones. Los datos fueron sometidos a las pruebas de Mann-Whitney y chi-cuadrado (α=0,05). Elnúmero de procedimientos analizados fue de 9706, 4693 en la institución [A] y 5013 en la [B]. En ambas instituciones, el número de procedimientos curativos (54,8%) fue significativamente superior al de procedimientos diagnósticos y asistenciales (45,2%) (p<0,001). En las clínicas de baja/media complejidad se observaron diferencias estadísticas en el número de procedimientos y/o en el número de alumnos que no se sometieron a determinados procedimientos clínicos. En las clínicas de alta complejidad se observaron diferencias estadísticas entre las instituciones en cuanto al número de procedimientos y/o el número de alumnos que no se sometieron a determinados procedimientos en Odontología, Cirugía, Periodoncia y Prótesis. La institución con mayor experiencia enel modelo de clínica integrada presentó mejores resultados en las especialidades de Odontología, Endodoncia y Prótesis (AU).

This study assessed and compared the clinical productivity of dental students in two private teaching institutions, with different lengths of experience in the integrated clinical model, recommended by the National Curriculum Guidelines (DCN). The universities have used the integrated clinical model since 2001 [A] and 2009 [B], with 5-year and 4-year undergraduate courses, respectively. The study was carried out from February to December 2019. Data were included for 205 students (56 from [A] and 149 from [B]) enrolled in low/medium (n=99) and high complexity clinics (n=106). The number of procedures performed by level of complexity in both institutions was assessed. Data were submitted to Mann-Whitney and chi-square tests (α=0.05). The number of procedures analyzed was 9706, 4693 in institution [A] and 5013 in [B]. In both institutions, the number of curative procedures (54.8%) was significantly higher than that of diagnostic and health care procedures (45.2%)(p<0.001). In low/medium complexity clinics, statistical differences were observed in the number of procedures and/or in the number of students who did not perform certain clinical procedures. In high-complexity clinics, statistical differences were observed between the institutions in terms of the number of procedures and/or the number of students who did not perform certain specific procedures in restorative dentistry, surgery, periodontics and prostheses. The institution with the longer experience in the integrated clinic model presented better results in the specialties of restorative dentistry, endodontics and prosthesis (AU).

Periapical Lesions Associated with Demographic Variables, Dental Conditions, Systemic Diseases, and Habits.

AIM AND BACKGROUND: The aim of this study was to analyze the prevalence of periapical lesions and possible associations with demographic, dental conditions, systemic diseases, and habit variables in patients from a private Brazilian university. MATERIALS AND METHODS: Data from 452 patients of both sexes, aged 18-78 years, from a Brazilian university were evaluated. Panoramic radiographs were analyzed, and the presence of periapical lesions was recorded. In these cases, the dental condition was assessed for the presence or absence of endodontic treatment. Medical records provide information related to general health (diabetes, cardiovascular diseases, altered cholesterol, autoimmune diseases, gallstones, or kidney stones) and habits (smoking or alcoholism). The data were descriptively analyzed, and then logistic regression and the Wald test were performed in Stata/SE v.14.1. RESULTS: A rate of 58.4% of participants were women, and the mean age was 36.4 (±14.6) years. Periapical lesions prevailed in 193 (42.7%) patients, and 281 (72.4%) teeth were not previously endodontically treated. Mandibular first molars (19%) and men (48.9%) were the most affected. The adjusted model showed that the age group of 26-45 years was 5 times more likely [odds ratio (OR) = 5.01; 95% confidence interval (CI): 2.85-8.82] to have lesions than those aged ≤25 years. Participants aged above 46 years were 19.1 times more prone (OR = 19.1; 95% CI: 10.2-36.0) to morbidity than younger ones (≤25 years). CONCLUSION: The studied sample showed that periapical lesions were more prevalent in males, in mandibular molars, and without prior endodontic treatment. There was no observed association between periapical lesions and comorbidities or habits; however, a significant correlation occurred with advancing age. CLINICAL SIGNIFICANCE: Comorbidities and habits were not associated with the presence of periapical lesions. However, aging has been identified as a significant risk factor for the development of periapical lesions. This finding is clinically relevant as it highlights the importance of monitoring and maintaining oral health in patients with advanced age. How to cite this article: dos Santos VC, de Oliveira Kublitski PM, Marques da Silva B, et al. Periapical Lesions Associated with Demographic Variables, Dental Conditions, Systemic Diseases, and Habits. J Contemp Dent Pract 2023;24(11):864-870.

Cleaning of long oval canals with WaveOne Gold system associated with different irrigant agitation protocols

Aim: The aim of the study was to evaluate the cleaning of mandibular incisors with WaveOne Gold® (WO) under different preparation techniques. Methods: A total of 210 human mandibular incisors were selected and divided into seven groups (n = 30), prepared by WO single-files (Small 20/.07 ­ WOS; Primary 25/.07 ­ WOP; Medium 35/.06 ­ WOM; or Large 45/.05 - WOL) and sequential-file techniques (WOS to WOP; WOS to WOM; and WOS to WOL). Further subdivision was made according to irrigation protocol: control group (manual irrigation - CON), E1 Irrisonic® - EIR, and EDDY® - EDD. Debris removal and the smear layer were evaluated by scanning electron microscopy. Data were analyzed by using Spearman's correlation test. The significance level was set at 5%. Results: For debris and smear layer removal, WOS and WOP, EIR differed from CON and EDD (p <0.05). Conclusion: Regardless of the instrumentation used, the agitation of the irrigant solution provided better cleanability. These findings reinforce the need for agitation techniques as adjuvants in cleaning root canal systems in mandibular incisors

Influence of different reciprocating systems on the apical extrusion of debris in flat-oval canals

Aim: To evaluate the apical extrusion of debris in flat-oval canals, using three reciprocating systems at two different working lengths (WL), 0 mm and 1 mm from the apical foramen. Methods: Ninety mandibular incisors were randomly divided into three groups based on the systems: WaveOne Gold #25.07 (WOG), ProDesign R #25.06 (PDR), and X1 Blue #25.06 (X1B). Extruded debris were collected and dried in pre-weighed Eppendorf tubes. Three consecutive weighings were performed for each tube, and the mean was calculated. If the assumptions of normality and homogeneity of variance were not met, the Kruskal-Wallis test was used to analyze the amount of extruded debris between groups with the same WL, and the Mann-Whitney U test was used for comparison within groups for each WL. Results: All groups had extruded debris, with higher median values occurring at 1 mm. No significant difference regarding the amount of debris extrusion was observed at 0 mm (p>0.05) and 1 mm (p>0.05) between groups. However, within the groups, at different WL, there was greater extrusion at 1 mm (p<0.05), with PDR differing significantly from the other systems (p<0.05). Conclusion: The extrusion of debris occurred regardless of the group, with higher values at 1 mm. However, using PDR at 1 mm from the apical foramen showed the highest values of extrusion

Educational approaches for assessing knowledge about and actions of educators in response to dental avulsion.

BACKGROUND: Dental trauma affects especially schoolchildren and adolescents. Educators, the responsible for the first appointment, have a fundamental role in the prognosis of dental avulsion that occurred in this environment. AIM: To evaluate the educational approaches for assessing knowledge and actions in response to dental avulsion among educators. SETTINGS AND DESIGN: This cross-sectional and quanti-qualitative study included 197 teachers and 24 pedagogical coordinators (PCs), from the public schools of Pato Branco, Paraná, Brazil. METHODS: A questionnaire was initially administered regarding the knowledge about avulsion to all participants. Teachers just read a manual and answered the questionnaire after 30 days. PCs were divided into (n = 12): G1 - manual + fictitious scenario of avulsion and G2 - active methodology + fictitious scenario. The questionnaire was re-administered to all. STATISTICAL ANALYSIS: Quantitative data were analyzed statistically. For the qualitative stage, two questions were proposed and the Bardin's analysis was performed. RESULTS: For teachers, knowledge about avulsion increased after the intervention (P < 0.001), except as related to cleaning the tooth (P = 0.21). Activities involving G1 and G2 also led to an increase in knowledge, but no difference occurred in this increase between the approaches (P = 0.14). Qualitative analysis highlighted the need for calm and for performing actions that could favor a good prognosis in cases of avulsion. CONCLUSIONS: The level of knowledge increased after interventions, but no significant differences between the educational approaches were found.

Postoperative Pain after Endodontic Treatment under Irrigation with 8.25% Sodium Hypochlorite and Other Solutions: A Randomized Clinical Trial.

INTRODUCTION: The aim of this study was to evaluate the postoperative pain in patients after endodontic treatment using 8.25% sodium hypochlorite (NaOCl) compared with other concentrations and 2% chlorhexidine (CHX). METHODS: In this double-blind randomized trial, 180 patients were evaluated who underwent a single session of endodontic treatment under irrigation with 2.5%, 5.25%, or 8.25% NaOCl or 2% CHX solutions. The presence of postoperative pain was assessed 24, 48, and 72 hours after treatment and recorded using the visual analog scale (VAS). A descriptive analysis, logistic regression, and Wald test were performed. RESULTS: Altogether 169 patients participated, of whom 107 were women, and the mean age was 38.1 ± 14.4 years. No significant differences occurred between the irrigants and the pain outcomes, not even for the use of postoperative pain medication and responses to VAS (P > .05). In the multivariate model including irrigants, after 24 hours or at any time, a significant difference (P < .05) remained in preparation time ≥10 minutes and the presence of overfilling. Also, in relation to the VAS, the overfilling presented significantly different results (P < .05). CONCLUSIONS: There was no significant difference in the presence of postoperative pain between the 8.25% NaOCl and the other irrigation solutions. However, the extended preparation time and the overfilling material were responsible for the increase of postoperative pain.

Biocompatibility of the 8.25% sodium hypochlorite irrigant solution in endodontics: An in vivo study.

The biocompatibility of irrigant solutions, including 8.25% sodium hypochlorite (NaOCl), was analyzed in samples (n = 25) of chorioallantoic membranes (CAM) from embryos of the Gallus gallus, using the hen's egg test on chorioallantoic membrane (HET-CAM). The following irrigants were tested: saline (control), 2% chlorhexidine (2% CHX), and NaOCl (2.5%, 5.25%, and 8.25%), and morphological and microcirculatory changes were investigated. Images were selected and quantified with Image J®. The macroscopic data were submitted to ANOVA, followed by the Tukey's test (p < .05); non-parametric Kruskal-Wallis and Mann-Whitney tests were applied to histological data (p < .05). The frequency of hyperemia differed significantly in the 8.25% NaOCl compared to the other groups, with the exception of 5.25% NaOCl (p = .096). Coagulation was more frequent in the 2% CHX group, differing significantly from the 2.5% NaOCl group (p = .038). In mean values, NaOCl 8.25% caused the decrease (NaOCl = 2.60, and control = 5.00) of vessels in the microcirculation, as well as triggered the increase (NaOCl = 425.50, and control 44.50) of inflammatory cells in the observed areas. There was necrosis in all samples in the 5.25% NaOCl group and in 80% in the 2% CHX, 2.5% NaOCl, and 8.25% NaOCl groups. Fibroblasts were detected only in the control group. It was concluded that the 8.25% NaOCl solution showed significantly high toxicity on CAM. However, these results were comparable to the other concentrations of NaOCl and to 2% CHX. Thus, in this experimental protocol, 8.25% NaOCl proved to be viable as an irrigant solution.

Effect of Root Canal Preparation on Propagation of Dentinal Microcracks.

Introduction: This study evaluated the propagation of dentinal microcracks and the root canal volume increase after being prepared with two endodontic instruments: ProTaper Next (PTN) and WaveOne Gold (WOG) by micro-computed tomography analysis. Methods and Materials: We selected 48 maxillary molars randomly distributed in two groups: PTN and WOG. The samples were scanned before and after instrumentation, and then the image analysis was performed to detect the propagation of pre-existing dentinal micro-cracks and calculate the pre- and post-instrumentation volume. The statistical analysis was performed using Student's t-test, Fisher's exact test, and ANCOVA (P<0.05). Results: Dentinal microcracks were observed in 95.8% of the samples, both PTN and WOG instruments propagated microcracks after instrumentation, but there was no significant difference between the instruments (P=0.538). In relation to the root canal volume there was no statistic difference between PTN and WOG systems for the mesiobuccal (P=0.426) and distobuccal root canals (P=0.523). Conclusion: We can conclude that both ProTaper Next and WOG systems propagate dentinal microcracks after root canal preparation in this in vitro study, without statistical significance. The root canal volume prepared also showed no statistically significant difference between the two groups. This in vitro study requires further studies for more concrete conclusions.

Descoloração da coroa após obturação endodôntica com diferentes cimentos: estudo clínico / Crown discoloration after endodontic obturation with different cements: a clinical study

Objetivo: O objetivo do presente estudo foi avaliar clinicamente a descoloração da coroa dentária após obturação do canal radicular com diferentes cimentos endodônticos. Métodos: Trinta e dois dentes foram tratados endodonticamente e obturados com AH Plus (AHP), Endofill (END), MTA Fillapex (MTA) ou Sealer 26 (SEA), divididos em oito pacientes por grupo. O registro das cores foi realizado com um espectrofotômetro antes da intervenção (T0 ), aos 30 (T1 ) e aos 90 dias após a intervenção (T2 ). As avaliações foram feitas no centro da coroa dentária e a variação de cor (ΔE) foi calculada por meio da Commission International de l'Eclai- rage (CIE) L*a*b. Um operador, especialista em Endodontia, realizou os procedimentos clínicos. Os dados foram submetidos a medidas repetidas ANOVA e teste de Tukey (Δ=5%). Resultados: Não houve diferença estatisticamente significativa na variação de cores entre os cimentos (AHP ΔE=4,11; END ΔE = 6,34; SEA ΔE = 8,77 e MTA ΔE = 12,15), p>0,05. Porém, houve diferença entre os períodos analisados (T1ΔE= 5,65; T2 ΔE = 10,02). Conclusões: Dentro das limitações deste estudo, todos os cimentos endodônticos causaram alterações cromáticas clinicamente perceptíveis na coroa dentária. No entanto, o AH Plus promoveu menos alterações cromáticas na coroa dentária (AU).

Introduction: The aim of this study was to evaluate the crown discoloration after root canal filling with different endodontic cements clinically. Methods: Thirty-two teeth were endodontically treated and filled with AH Plus (AHP), Endofill (END), MTA Fillapex (MTA), or Sealer 26 (SEA), divided into eight patients per group. Color recording was performed with a spectrophotometer before the intervention (T0 ) and at 30 (T1 ) and 90 days post-intervention (T2 ). The evaluations were done in the center of the dental crown and color variation (ΔE) was calculated by means of the Commission International de IEclairage (CIE) L*a*b. The data were subjected to repeated measures ANOVA and Tukeys test (alpha=5%). Results: There was no statistically significant difference in color variation between the cements (AHP ΔE=4.11; END ΔE=6.34; SEA ΔE=8.77, and MTA ΔE=12.15), p>0.05. However, there was a difference between the periods tested (T1 ΔE=5.65; T2 ΔE=10.02). Conclusions: All tested endodontic cements altered the color of dental crowns (AU).

Effects of 1-Ethyl-3-(3-Dimethylaminopropyl) Carbodiimide on Adhesion of Posts in Teeth Obturated With Different Sealers.

The aim of this study was to evaluate the effect of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) on bond strength of fiberglass posts in root canals obturated with different endodontic sealers. Seventy-eight mandibular premolars were obturated with three sealers (n=26): Endofill (END), AH Plus (AHP), and Endosequence BC Sealer (EBS). After preparation of the post space, two subgroups were formed according to the cementation of the posts (n=13): with EDC (EDC), and without EDC (control - CON). The specimens were submitted to a pull-out test, failure mode classification, and root canal surface evaluation by scanning electron microscopy after post displacement. Regarding the bond strength, a significant difference between the EDC and CON subgroups occurred only in the END (p=0.001). No difference was detected among the CON subgroups (p=0.339). However, among the EDC subgroups, AHP presented significantly higher values (END versus AHP: p=0.001; AHP versus EBS: p=0.016). Upon classification of failure modes, score 1 (≥ 50% of cement) was the most commonly observed, except for the END + EDC. Remains of endodontic sealers and resin cements were found in the cervical third, but without statistical difference (p=0.269), while in the middle third, difference occurred (p=0.004). In conclusion, EDC decreases bond strength when associated with END sealer, without changing the failure mode between the resin cement and fiberglass post. The best performance was observed when EDC was combined with AHP sealer.

Comparison of Canal Transportation and Centering Ability of ProGlider and WaveOne Gold Glider in Curved Canals.

OBJECTIVES: The aim of this study was to compare the volume variation and maintenance of the root canal position when using the ProGlider 16.02 (PG) and the WaveOne Gold Glider 15.02 (WOGG) file systems for glide path preparation. MATERIALS AND METHODS: Twenty-four moderately curved mesiobuccal canals of maxil-lary first molars were selected and randomly divided into two groups: PG and WOGG. The selected teeth were scanned using microtomography before and after root canal preparation to assess centralization and linear transport at 1, 3, 5, and 7 mm from the apical foramen. STATISTICAL ANALYSIS: The data were analyzed with the Mann-Whitney U test. The level of significance was 5%. RESULTS: There were no significant differences in volume variation or root canal transport (p > 0.05). There was a significant difference in the centralization of the root canal at 3 mm from the foramen (p < 0.05). CONCLUSIONS: WOGG and PG instruments presented similar results regarding the root canal volume increase and transport. WOGG caused higher decentralization at 3 mm from the apical foramen.

Cone-Beam Computed Tomography Detection of Separated Endodontic Instruments.

INTRODUCTION: This study compared the accuracy, sensitivity, and specificity of different imaging diagnostic protocols, cone-beam computed tomography (CBCT) and digital periapical radiography (DPR), in identifying separated endodontic instruments in filled root canals. METHODS: One hundred eight root canals from 36 mandibular molars were prepared and obturated. Of these, 84 were filled without separated instruments, and 24 were filled with the presence of a separated instrument (stainless steel hand file or reciprocating instrument). Subsequently, different CBCT imaging protocols were acquired: i-CAT Classic (ICC) (0.25-mm isotropic voxel), i-CAT Next Generation (ICN) (0.125-mm isotropic voxel), and PreXion 3D (PXD) (0.09-mm isotropic voxel). Moreover, a DPR exam was obtained (08 mA, 70 kVp, and exposure time of 0.2 seconds). Two calibrated endodontists evaluated each image for the presence or absence of fractured files on a 5-point scale, ranging from definitely absent to definitely present. The accuracy, sensitivity, and specificity measures for each method were estimated. The data were evaluated by Fisher exact test and binomial test. RESULTS: Nine instruments were identified in DPR (37.5%) and none in the CBCT protocols (P > .05). The type of instrument (stainless steel hand file or reciprocating instrument) did not influence the identification of the separated instrument (P > .05). This study showed that DPR is the most accurate and sensitive imaging technique, with 83.3% and 37.5%, respectively. CONCLUSIONS: DPR is the better imaging diagnostic exam to evaluate the presence of separated endodontic instruments inside a root canal in comparison with the ICC, ICN, and PXD tomographic protocols. However, most of the separated instruments were not identified.

Effects of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide on adhesion of posts in teeth obturated with different sealers

Abstract The aim of this study was to evaluate the effect of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) on bond strength of fiberglass posts in root canals obturated with different endodontic sealers. Seventy-eight mandibular premolars were obturated with three sealers (n=26): Endofill (END), AH Plus (AHP), and Endosequence BC Sealer (EBS). After preparation of the post space, two subgroups were formed according to the cementation of the posts (n=13): with EDC (EDC), and without EDC (control - CON). The specimens were submitted to a pull-out test, failure mode classification, and root canal surface evaluation by scanning electron microscopy after post displacement. Regarding the bond strength, a significant difference between the EDC and CON subgroups occurred only in the END (p=0.001). No difference was detected among the CON subgroups (p=0.339). However, among the EDC subgroups, AHP presented significantly higher values (END versus AHP: p=0.001; AHP versus EBS: p=0.016). Upon classification of failure modes, score 1 (≥ 50% of cement) was the most commonly observed, except for the END + EDC. Remains of endodontic sealers and resin cements were found in the cervical third, but without statistical difference (p=0.269), while in the middle third, difference occurred (p=0.004). In conclusion, EDC decreases bond strength when associated with END sealer, without changing the failure mode between the resin cement and fiberglass post. The best performance was observed when EDC was combined with AHP sealer.

Resumo O objetivo deste estudo foi avaliar o efeito da 1-etil-3- (3-dimetilaminopropil) carbodiimida (EDC) na resistência de união de pinos de fibra de vidro em canais radiculares obturados com diferentes cimentos endodônticos. Setenta e oito pré-molares inferiores foram obturados com três cimentos endodônticos (n=26): Endofill (END), AH Plus (AHP) e Endosequence BC Sealer (EBS). Após o preparo do espaço para pino, dois subgrupos formaram-se conforme a cimentação dos pinos (n=13): com EDC e sem EDC (controle - CON). Os espécimes foram submetidos ao teste pull-out, classificação do modo de falha e avaliação da superfície do canal radicular por microscopia eletrônica de varredura após o deslocamento. Quanto à força de resistência de união, uma diferença estatisticamente significativa ocorreu entre os subgrupos EDC e CON apenas no END (p=0,001). Não foi detectada diferença entre os subgrupos CON (p=0,339). Contudo, no subgrupo EDC, o AHP apresentou maiores valores (END versus AHP: p=0,001; AHP versus EBS: p=0,016). Acerca da classificação dos modos de falha, o escore 1 (≥50% de cimento) foi o mais comumente observado, exceto para END + EDC. Restos de cimentos endodônticos e cimentos resinosos foram encontrados no terço cervical, mas sem diferença estatística (p=0,269), enquanto no terço médio, houve diferença (p=0,004). Em conclusão, o EDC diminui a resistência de união quando associado ao cimento END, sem alterar o modo de falha entre o cimento resinoso e o pino de fibra de vidro. O melhor desempenho foi observado quanto o EDC foi usado com o cimento AHP.

Temperature changes affect the rheological properties of a silicone-based and an epoxy resin-based root canal sealers.

To evaluate temperature changes on the rheological properties (setting time and complex viscosity (η*)) of GuttaFlow Bioseal (GFB) and AH Plus Jet (AHPJ). Rheological measurements were performed in oscillating mode at the strain amplitude and angular frequency of 0.01% and 10 rad s-1 , respectively. Each sealer (n = 5) was tested running a temperature ramp (rapid increase to 80°C, 1 min constantly at 80°C, and slower decrease to 37°C). Control groups (n = 5) were tested at a constant temperature of 37°C. Kolmogorov-Smirnov and one-way ANOVA (P < 0.05) statistical tests were performed. The temperature ramp reduced setting time of GFB (24.85 to 4.45 min) (P < 0.05), but did not alter that of AHPJ (P > 0.05). GFB exhibited an increased η*, whereas the AHPJ η* was decreased when heated (P < 0.05). Rheological properties of sealers were negatively affected by temperature changes.

Influence of the Preparation Order in Four-Canal Maxillary Molars with WaveOne Gold System.

INTRODUCTION: The aim of this study was to evaluate the effect of the order of preparation of four-canal maxillary molars on volume variation, instrument deformation, cyclic fatigue, and preparation time by using the WaveOne Gold Primary (WOG 25.07). METHODS: We selected 48 permanent, human, four-canal maxillary molars. The teeth were divided into 4 groups according to the order of initiation of the canal preparation sequence: (1) mesiobuccal (MB), distobuccal (DB), palatal (P), second mesiobuccal (MB2); (2) DB-P-MB2-MB; (3) P-MB2-MB-DB and (4) MB2-MB-DB-P. Pre- and post-preparation microtomography scanning was performed to obtain initial and final canal volume measurements. The instruments were also evaluated by using scanning electron microscopy to determine the wear and deformation present after use. The active instrumentation time was also recorded. The data were statistically compared by using a significance level of 5%. RESULTS: No statistically significant difference was found between groups for volume variation and time of preparation of the canals with the WOG system (P > .05); however, a statistically significant difference was observed in the deformation of the instruments. In the comparison between the groups for MB-DB-P-MB2 and P-MB2-MB-DB, the latter presented greater deformation of the instruments. CONCLUSIONS: Root canal preparation sequence affected deformation of the instruments but did not influence the volume variation or the canal preparation time with the WOG system. To minimize instrument deformation, the preparation order should be MB-DB-P-MB2.

Effect of Vehicle and Agitation Methods on the Penetration of Calcium Hydroxide Paste in the Dentinal Tubules.

INTRODUCTION: The aim of this ex vivo study was to analyze the effect of different vehicles combined with agitation methods on the penetration of calcium hydroxide (CH) paste in the dentinal tubules. METHODS: Sixty freshly extracted, single-rooted human premolars were prepared using WaveOne Gold (Dentsply Sirona, York, PA) and randomized into 6 experimental groups (n = 10) according to the vehicle and method of paste agitation as follows: propylene glycol (PG) + Lentulo, PG + Lentulo + ultrasound, PG + Lentulo + sonic, distilled water (DW) + Lentulo, DW + Lentulo + ultrasonic, and DW + Lentulo + sonic. The CH paste was manipulated with sodium fluorescein dye and was inserted to completely fill the root canal. Two 1-mm thick sections at 2 mm and 5 mm from the apex of each root were obtained. The sections were scanned using confocal laser scanning microscopy, and the images were analyzed using ImageJ software (Bethesda, MD) to calculate the percentage penetration and maximum penetration depth of CH paste. Statistical analysis was performed using 1-way analysis of variance and Tukey honestly significant difference post hoc tests. RESULTS: No statistically significant differences between study factors at a distance of 2 mm from the apex were observed (P > .05). However, at 5 mm, a significant difference between the vehicles (P < .05) in percentage penetration was demonstrated with higher means for PG. CONCLUSIONS: Vehicles interfered with the penetration of CH in the dentinal tubules at 5 mm from the apex with better results for PG.

Influence of activation mode and preheating on intracanal irrigant temperature.

This ex vivo study assessed the effectiveness of two activation modes to increase the intracanal temperature of 5.25% NaOCl solution and the time for a preheated-irrigant to return to its initial temperature. Ten single-rooted extracted human teeth were used. Thermocouples were adapted to the root surface and the temperature was registered following two activation modes: ultrasound (US) and thermal. Furthermore, a preheated-solution (45°C/60°C) was flushed into root canal to test the time needed to return to its initial temperature. Data were analysed using two-way ANOVA and Tukey's post-hoc tests (P = 0.05). Statistical analysis showed differences between the activation modes. US and thermal activation increased from 37 to 40.4°C and to 62.8°C respectively in 60 s. Time for preheated-irrigant to return to its initial temperature was longer for 60°C. Preheating irrigant at 60°C and using thermal activation to keep it warm may represent a further step of the irrigation protocol.

Analysis of reciprocating system real-time torque variation during root canal preparation.

OBJECTIVE: This study monitored real-time torque variation of the WaveOne Gold (WOG) and Reciproc Blue (RB) during root canal preparation of mandibular molars. Thirty-six mandibular molars were prepared with WOG Primary 25.07 (WOGP, n = 36) and the RB R25 25.08 (RBR25, n = 36) for the mesial canals, whereas WOG Large 45.05 (WOGL, n = 18) and RB R40 40.06 (RBR40, n = 18) for the distal. Canal preparation was divided into thirds and the torque, maximum torque and time, were recorded. RESULTS: The RBR25 instruments exhibited higher maximum torque in the apical third in contrast to the WOGP instruments (p < 0.05). The intragroup analysis found a significant difference in maximum torque between the cervical and apical thirds, and the middle and apical thirds (p < 0.05) for both instruments (RBR25 and WOGP). The WOGP group had the shortest preparation time (p < 0.05). There were no significant differences between the WOGL and RBR40 for any of the parameters evaluated (p > 0.05). The RBR25 had the highest torque when compared to the WOGP. Both instruments exhibited higher torque in the apical third and there were no significant differences between the instruments in the distal canal.