Incidence of Dentinal Defects and Vertical Root Fractures after Endodontic Retreatment and Mechanical Cycling

Introduction: The aim of this study was to evaluate the incidence of dentinal defects and vertical root fractures (VRFs) after endodontic retreatment and mechanical cycling (MC). Methods and Materials: Two hundred mandibular premolars were selected. Forty teeth were left unprepared (control group). The remaining 160 root canals were prepared with ProTaper instruments and filled by using two different techniques [eighty with lateral compaction (LC) and eighty with single-cone (SC)]. Forty canals from each group (LC and SC) received no further treatment. The remaining eighty teeth were divided into two groups (LCR and SCR) (n=40) in order to undergo the removal of the root filling, re-preparation and refilling with lateral compaction and single-cone, respectively. All of the teeth were subjected to MC (1,000,000 cycles, 130 N, 2.2 Hz and 37°C). The roots were sectioned at 3, 6 and 9 mm from the apex and observed under 20× magnification. The defects were classified as: no defect, VRF and other defects. Statistical analysis was performed using the Fisher’s Exact test and the Chi-Squared tests (α=0.05). Results: MC alone did not promote any other defects or VRFs. Experimental groups presented higher dentinal defects than the control group (P=0.021). Retreatment groups did not present a higher amount of dentinal defects than the groups that were subjected to the first treatment (P>0.05). Conclusion: Endodontic treatment and retreatment, regardless of the filling technique and MC, did not influence the occurrence of dentinal defects or VRFs in the human premolars.Keywords: Defects; Endodontics; Retreatment; Root Cana

Avaliação da infiltração marginal dos materiais MTA, Cimento de Portland e Ionômero de Vidro empregados em obturações retrógadas

Objetivos. Avaliar o selamento apical promovido pelo MTA, cimento de Portland e ionômero de vidro em retrocavidades de dentes incisivos centrais superiores humanos.Método. Trinta incisivos centrais superiores foram tratados endodonticamente e tiveram sua porção apical seccionada, cavidades retrógadas foram preparadas e em seguida divididas em três grupos de dez dentes cada, da seguinte forma: Grupo1 – MTA; Grupo 2 – cimento de Portland; e Grupo 3 – ionômero de vidro. Dois dentes ainda foram utilizados, um como controle positivo e outro como controle negativo. Após a imersão no corante rodamina B a 0,2% por 48h a 37ºC as raízes foram clivadas e o padrão de infiltração foi mensurado. Os dados foram analisados utilizando-se ANOVA seguido pelo Teste Post Hoc de Bonferroni (p 0,05).Conclusão. Segundo a metodologia empregada, concluiu-se que o material que proporcionou o melhor selamento apical em retrobturações endodônticas foi o ionômero de vidro

Perfil de resistência a agentes antimicrobianos de bactérias anaeróbias isoladas de infecções endodônticas agudas

A presente tese teve como objetivos analisar o padrão de resistência a antimicrobianos de bactérias isoladas de infecções endodônticas agudas por meio de uma revisão sistemática e meta-análise (capítulo 1); identificar e determinar a diversidade genotípica, a sensibilidade bacteriana e os fatores de virulência de anaeróbios facultativos isolados em casos de abscesso apical agudo (capítulo 2); e realizar, por meio de uma proposta de informativo, a difusão de informações geradas com orientações sobre o uso de agentes antibióticos em infecções endodônticas agudas para dentistas e pacientes (capítulo 3). A revisão sistemática foi realizada por meio de pesquisa em base de dados na internet e na literatura cinza até maio de 2015. As normas do PRISMA foram seguidas. Estudos clínicos em humanos que avaliaram o perfil de resistência a antimicrobianos de isolados de infecções endodônticas agudas primárias por meio de métodos laboratoriais foram incluídos. O efeito randômico da Meta-análise foi empregado, e o desfecho foi descrito reunindo as taxas de resistência para cada antibiótico testado. Os dados de sete estudos foram extraídos. A taxa de resistência para 15 diferentes agentes antibióticos foram avaliadas, variando entre 3,5% a 40%. Baixas taxas de resistência foram observadas para amoxicilina + clavulanato e amoxicilina, e altas taxas foram observadas para tetraciclina. No capítulo 2, amostras de canais radiculares foram coletadas de sete dentes com diagnóstico de abscesso apical agudo. Bactérias anaeróbias facultativas foram identificadas com o auxílio de métodos fenotípicos e MALDI-TOF MS. A sensibilidade antimicrobiana das cepas isoladas foi determinada para benzilpenicilina, eritromicina e clindamicina por meio da difusão em disco. Bactérias anaeróbias facultativas foram isoladas de 3 dentes. Streptococcus spp., Staphylococcus aureus, Enterococcus faecalis, e Actinomyces viscosus foram identificados. Streptococcus spp. e S. aureus foram sensíveis à benzilpenicilina. E. faecalis (24 cepas) isolados de um mesmo paciente tiveram a sensibilidade antimicrobiana determinada por meio da concentração inibitória mínima para benzilpenicilina, amoxicilina e amoxicilina + clavulanato utilizando-se o E-test. A diversidade genotípica e a presença de fatores de virulência (ace, asa, gelE, efaA, cylA, esp) nas cepas de E. faecalis foi analisada por meio do PFGE e PCR, respectivamente. A expressão da gelatinase e da hemolisina foi testada, e a produção de biofilme quantificada. E. faecalis foram sensíveis aos antibióticos beta-lactâmicos. O mesmo perfil cromossonal de DNA foi revelado para cepas de E. faecalis isoladas. Os genes gelE, ace e efaA foram detectados em 18 cepas. A expressão da gelatinase e a produção de biofilme foram observadas. Cepas de E. faecalis tiveram o mesmo perfil de DNA cromossomal, porém parecem apresentar diferentes perfis de virulência. No capítulo 3 foram apresentadas duas propostas de textos informativos. A primeira com o objetivo de orientar o dentista sobre o uso correto dos antibióticos sistêmicos em endodontia. A segunda visa informar os pacientes sobre a utilização dos antibióticos e esclarecer possíveis dúvidas.The present thesis aimed to analyze the antimicrobial resistance profile of bacteria isolated from acute endodontic infections through a systematic review and meta-analysis (Chapter 1); to identify and determine the genotypic diversity, antimicrobial susceptibility and virulence factors of isolated facultative anaerobes in isolates from acute apical abscess (Chapter 2); and to provide information for dentist and patients generated from guidelines on the use of antibiotic agents in acute endodontic infections (Chapter 3). The electronic databases and the gray literature were searched up to May 2015 for systematic review. PRISMA guidelines were followed. The clinical studies in of humans that have evaluated the antimicrobial resistance of the isolates of primary acute endodontic infections through laboratorial methods were included. A random effect meta-analysis was employed, and the outcome was described as being the pooled resistance rates for each antimicrobial agent. The data from 7 studies were extracted. The resistance rates for 15 different antimicrobial agents were evaluated, ranging from 3.5% to 40.0%. Lower resistance rates were observed for amoxicillin+clavulanate and amoxicillin, and higher resistant rates were detected for tetracycline. In Chapter 2, root canal samples were collected from seven teeth. Facultative anaerobic bacteria were identified by phenotypic methods and MALDI-TOF MS. Antimicrobial susceptibility of strains was determined to benzylpenicillin, erythromycin and clindamycin by disk-diffusion. Facultative anaerobic bacteria were isolated from 3 teeth. Streptococcus spp., Staphylococcus aureus, Enterococcus faecalis, and Actinomyces viscosus were found. Streptococcus spp. and S. aureus were susceptible to benzylpenicillin. E. faecalis strains (n=24) isolated from the same patients had their susceptibility determined by minimum inhibitory concentration of benzylpenicillin, amoxicillin and amoxicillin + clavulanate using the E-test. The genotypic diversity and virulence factors (ace, asa, gelE, efaA, cylA, esp) were analyzed in E. faecalis strains by PFGE and PCR, respectively. Phenotypic expression of gelatinase and cytolysin were tested. Biofilm production was quantified. All the E. faecalis strains were susceptible to β-lactam antibiotics. The same chromosomal DNA fragmentation profile was revealed to E. faecalis strains isolated. The gelE, ace and efaA genes were detected in 18 E. faecalis strains. Gelatinase expression and biofilm production were observed. E. faecalis strains had the same chromosomal DNA profile, but showed virulence profiles different. In Chapter 3, two sugestion for information texts were presented. The first aims to guide dentists on the proper use of systemic antibiotics in endodontics. The second aims to inform patients about the use of antibiotics and clarify possible doubts

Efficacy of passive ultrasonic irrigation in removing root filling material during endodontic retreatment

Abstract Introduction The aim of endodontic retreatment is to remove the previous root filling materials completely to allow for the subsequent steps of cleaning, canal shaping and filling replacement. Objective To evaluate the efficacy of passive ultrasonic irrigation (PUI) in the removal of residual root filling material after removing the bulk of the root filling with nickel-titanium rotary instruments. Material and method Eighteen mesial isthmus-containing roots of human mandibular molars were prepared and filled. The root canal filling was removed with the ProTaper Retreatment system and K-files. The specimens were randomized into 2 groups (n = 9), both irrigated with 2.5% NaOCl and 17% EDTA. In the conventional group, an irrigation syringe was used. In the PUI group, the PUI technique was used. The roots were sectioned longitudinally and evaluated under stereomicroscopy. Student’s t test was used to compare groups and the general linear model was used to compare the apical, cervical, and middle root thirds within each group, in regard to the percentages of remaining residual filling material. Result There was no statistically significant intergroup difference, irrespective of which root third was evaluated (P > 0.05). In the PUI group, the apical third showed a significantly higher percentage of residual filling material, in comparison with the cervical (P = 0.038) and middle (P = 0.029) thirds. Conclusion The PUI technique was not more effective than the conventional irrigation technique in removing residual root filling material during endodontic retreatment in root canals with a complex anatomy

Efficacy of passive ultrasonic irrigation in removing root filling material during endodontic retreatment

Abstract Introduction The aim of endodontic retreatment is to remove the previous root filling materials completely to allow for the subsequent steps of cleaning, canal shaping and filling replacement. Objective To evaluate the efficacy of passive ultrasonic irrigation (PUI) in the removal of residual root filling material after removing the bulk of the root filling with nickel-titanium rotary instruments. Material and method Eighteen mesial isthmus-containing roots of human mandibular molars were prepared and filled. The root canal filling was removed with the ProTaper Retreatment system and K-files. The specimens were randomized into 2 groups (n = 9), both irrigated with 2.5% NaOCl and 17% EDTA. In the conventional group, an irrigation syringe was used. In the PUI group, the PUI technique was used. The roots were sectioned longitudinally and evaluated under stereomicroscopy. Student’s t test was used to compare groups and the general linear model was used to compare the apical, cervical, and middle root thirds within each group, in regard to the percentages of remaining residual filling material. Result There was no statistically significant intergroup difference, irrespective of which root third was evaluated (P > 0.05). In the PUI group, the apical third showed a significantly higher percentage of residual filling material, in comparison with the cervical (P = 0.038) and middle (P = 0.029) thirds. Conclusion The PUI technique was not more effective than the conventional irrigation technique in removing residual root filling material during endodontic retreatment in root canals with a complex anatomy