Resumo Este estudo avaliou o impacto do pré-alargamento do canal usando uma lima K de tamanho #25 na incidência de fraturas de três instrumentos reciprocantes após múltiplos usos. Após um glide path realizado com uma lima K de tamanho #15, os instrumentos (Reciproc R25, Reciproc Blue R25, e WaveOne Gold Primary) foram inicialmente usados em 936 canais radiculares. Depois, para o segundo e terceiros usos (933 e 927 canais, respectivamente), um pré-alargamento usando uma lima K de tamanho #25 no comprimento de trabalho foi realizado. Radiografias periapicais avaliaram a localização e o comprimento dos fragmentos, e os testes qui-quadrado compararam as frequências observadas e esperadas (α = 5%). A incidência de fraturas durante o reuso variou de 0% a 0,64%. Reciproc não fraturou durante o reuso (P = 0,99), mas sofreu duas fraturas no terceiro uso (P = 0,000). Reciproc Blue e WaveOne Gold tiveram, cada um, uma fratura durante o segundo (P = 0,000) e terceiro (P = 0,000) usos. Após o pré-alargamento do canal usando uma lima K de tamanho #25 em 1.860 canais, apenas 6 instrumentos fraturaram (0,32%), sugerindo que esta abordagem pode prolongar a vida útil desses instrumentos e servir como uma alternativa para sua reutilização com risco reduzido de fratura. préalargamento pré alargamento 25 #2 15 #15 R25 R Primary 93 radiculares Depois 933 (93 92 respectivamente, respectivamente , respectivamente) fragmentos quiquadrado qui quadrado α 5%. 5 5% . 5%) 0 064 64 0,64% P 0,99, 099 0,99 99 0,99) 0,000. 0000 0,000 000 tiveram 1860 1 860 1.86 0,32%, 032 0,32% 32 (0,32%) 2 # #1 R2 9 (9 06 0,64 09 0,9 0,00 00 186 86 1.8 03 0,32 3 (0,32% ( 0,6 0, 0,0 18 8 1. 0,3 (0,32 (0,3 (0, (0

Abstract This study assessed the impact of pre-enlarging the root canal using a size 25 K-file on the fracture incidence of three reciprocating instruments after multiple uses. After a glide path performed with a size 15 K-file, the instruments (Reciproc R25, Reciproc Blue R25, and WaveOne Gold Primary) were initially used in 936 root canals. Then, for the second and third uses (933 and 927, respectively), a pre-enlargement using a size 25 K-file at the working length was done. Periapical radiographs assessed fragment location and length, and chi-square tests compared observed and expected frequencies (α = 5%). The fracture incidence during reuse ranged from 0% to 0.64%. Reciproc did not fracture during reuse (P = 0.99), but experienced two fractures in the third use (P = 0.000). Reciproc Blue and WaveOne Gold each had one fracture during the second (P = 0.000) and third (P = 0.000) uses. Following a pre-enlargement using a size 25 K-file for the second and third uses in 1,860 canals, only 6 instruments fractured (0.32%), suggesting that this approach may prolong the lifespan of these instruments and serve as an alternative for their reuse with a reduced risk of fracture. preenlarging pre enlarging 2 Kfile K file 1 Kfile, file, R25 R Primary 93 canals Then 933 (93 927 respectively, respectively , respectively) preenlargement enlargement done chisquare chi square α 5%. 5 5% . 5%) 0 064 64 0.64% P 0.99, 099 0.99 99 0.99) 0.000. 0000 0.000 000 1860 860 1,86 0.32%, 032 0.32% 32 (0.32%) R2 9 (9 92 06 0.64 09 0.9 0.00 00 186 86 1,8 03 0.32 3 (0.32% ( 0.6 0. 0.0 18 8 1, 0.3 (0.32 (0.3 (0. (0

Abstract This study compared the effects of different final irrigation protocols on the mechanical properties and structural integrity of root dentine. One-hundred eight teeth were instrumented and irrigated with sodium hypochlorite (NaOCl) using conventional irrigation (CI). Teeth were distributed into four groups based on final irrigation protocols: Control Group (CG): 17%EDTA/CI + H2O; G1: 2.5%NaOCl/Passive Ultrasonic Irrigation (PUI) + EDTA/PUI + NaOCl/PUI (60s each); G2: EDTA/PUI + NaOCl/PUI (30s each); G3: EDTA/PUI + NaOCl/PUI + H2O/PUI + CHX/PUI (30s each). Four tests were conducted: three-point flexural strength test, Scanning Electron Microscopy analysis, microhardness assessment, and the push-out bond strength (POBS) of the filling material to the root dentine. Data were analyzed using ANOVA and Tukey tests (Flexural strength), and Student t-test (Microhardness). Erosion scores and POBS were analyzed by Kruskal-Wallis and Dunn tests (α = 0.05). Results indicated no significant differences in flexural strength (p > 0.05) among groups. CG exhibited the lowest erosion scores in the cervical third. In the middle third, CG had lower scores than G1 and G2, while in the apical third, CG had lower scores than G1 (p < 0.05). Microhardness values decreased following the protocols (p < 0.05), except for the CG (p > 0.05). G2 displayed higher POBS values in the middle and apical thirds (p < 0.05). The protocols did not significantly influence the flexural strength of root dentine. However, they did affect microhardness and promoted greater erosion. The best results for POBS were observed when the final irrigation involved the sequential use of EDTA and NaOCl employing PUI for 30 seconds in each solution. dentine Onehundred One hundred (NaOCl CI. CI . (CI) (CG) 17EDTACI EDTACI 17 H2O HO H O G 25NaOClPassive NaOClPassive 2 5 Passive (PUI EDTAPUI NaOClPUI 60s s each) 30s G3 H2OPUI HOPUI CHXPUI CHX each. conducted threepoint three point test analysis assessment pushout push out (POBS Flexural strength, , strength) ttest t Microhardness. (Microhardness) KruskalWallis Kruskal Wallis α 0.05. 005 0.05 0 05 p third 0.05, However 3 solution (CI (CG 1 OPUI (Microhardness 00 0.0 0.

Resumo Este estudo avaliou os instrumentos Reciproc R25 e Pro-R 25 sem uso, após um primeiro e um segundo uso em retratamento endodôntico com perfilômetro 3D por interferometria de luz sem contato, microscópio eletrônico de varredura (MEV) e testes de fadiga cíclica. Vinte dentes unirradiculares foram instrumentados com Reciproc R25 e obturados com guta-percha e cimento endodôntico. Um perfilômetro 3D com uma objetiva 20x usando o software Mx ™ foi usado para avaliar as superfícies da lâmina de corte do Reciproc e Pro-R (n = 5 por grupo) na condição sem uso, após o primeiro e após um segundo uso em procedimentos de retratamento. Após retratamento, o MEV foi usado para avaliar as características topográficas dos instrumentos utilizados. Testes de fadiga cíclica foram realizados para comparar instrumentos novos com instrumentos usados. O teste One-way ANOVA seguido pelo teste de Tukey foi usado para comparar os instrumentos testados nos diferentes estágios. Para comparar os diferentes instrumentos e para avaliação de fadiga cílcica, foi utilizado o Student t-test. Não foram observadas diferenças estatisticamente significantes nas superfícies das lâminas de corte dos instrumentos Reciproc e Pro-R antes e após um e dois usos (p> 0,05). O Reciproc na condição sem uso apresentou maior Sa e Sq quando comparado ao Pro-R (p <0,05). Não foram observadas diferenças entre Reciproc e Pro-R após um e dois usos (p> 0,05). O Reciproc sem uso apresentou maior tempo de fratura do que os instrumentos Pro-R (p<0,05), e apenas o Pro-R apresentou diferenças entre instrumentos novos e usados (p<0,05). Os procedimentos de retratamento com Reciproc e Pro-R não alteraram a topografia da superfície dos instrumentos. Reciproc apresentou maior resistência à fadiga cíclica em comparação com o Pro-R.

Abstract This study evaluated the Reciproc R25 and Pro-R 25 instruments in unused condition, after one and a second use in endodontic retreatment employing a noncontact 3D light interferometer profiler, scanning electron microscopy (SEM) and cyclic fatigue tests. Twenty single-root teeth were instrumented with Reciproc R25 and filled with gutta-percha and sealer. A 3D profiler with a 20x objective using the Mx™ software was used to evaluate the cutting blade surfaces of Reciproc R25 and Pro-R 25 (n=5 per group) in unused condition, after the first and second uses in retreatment procedures. After retreatment, SEM was used to evaluate the topographic features of the used instruments. Cyclic fatigue tests were performed to compare new to used instruments. One-way ANOVA followed by Tukey test was used to compare the tested instruments before and after the first and second uses. Student t-test was used to compare the different instruments and for cyclic fatigue evaluation. No significant differences were observed in the cutting blade surfaces of Reciproc and Pro-R before and after one and two uses (p>0.05). Reciproc without use showed higher Sa and Sq when compared to Pro-R without use (p<0.05). No differences were observed between Reciproc and Pro-R after one and two uses (p>0.05). New and unused Reciproc showed longer time to fracture than Pro-R instruments (p<0.05), and only Pro-R showed differences between new and used instruments (p<0.05). Retreatment procedures with Reciproc and Pro-R did not change the surface topography of instruments. Reciproc had greater resistance to cyclic fatigue compared with Pro-R.

Abstract This study evaluated the cytotoxicity, the antimicrobial and physicochemical properties of root canal sealers incorporated with phytotherapic Uncaria tomentosa (UT). Unmodified AH Plus (Dentsply, DeTrey, Germany) and MTA Fillapex (Angelus, Londrina, Brazil) were used as controls. UT was incorporated into AH Plus and MTA Fillapex, at concentrations of 2% and 5% of the total weight of these sealers (w/w). Flowability, setting time, and solubility were evaluated following ISO requirements. The pH values were measured at periods of 12, 24, 48 hours, and 7 days. The antimicrobial activity of the sealers against Enterococcus faecalis was analyzed by both direct contact tests in freshly prepared sealers, and after 7 days. The cytotoxicity of the samples was evaluated by the MTT assay, to check Balb/c 3T3 cell viability. The statistical analysis was performed by one-way ANOVA and Tukey’s test (p < 0.05). The incorporation of UT was associated with a decrease in flow, for both sealers, an increase in AH Plus setting time, increase in MTA Fillapex pH values, and solubility (after 14 days), for both sealers (p < 0.05). Regarding the antibacterial evaluation, bacterial reduction was reported after incorporation of UT into both AH Plus and MTA Fillapex, up to 7 days after handling of the material (P<0.05). UT incorporation decreased the cytotoxic effects of both AH Plus and MTA Fillapex sealers in a way directly proportional to their respective concentrations (p < 0.05). In conclusion, UT can be added to both sealers to reduce their cytotoxicity, and improve their antibacterial effects, without compromising their original physicochemical properties.

Abstrac The aim of the present study was to evaluate the cyclic fatigue, torsional resistance and surface roughness of Reciproc R25 instruments in four different situations, namely as new instruments and as instruments tested after clinical preparation of one, two or three maxillary molars with four root canals. The total time required to perform each root canal preparation was recorded. Cyclic fatigue resistance was determined by the time to fracture using a customized testing device (n = 10 per group). The torsional test evaluated the torque and angle of rotation to failure according to ISO 3630-1 (n = 10 per group). The roughness of the working parts of new and used instruments was evaluated with a profilometer (n = 5 per group). Statistical analysis was performed using one-way ANOVA and Tukey’s test. The level of significance was set at 5%. No fractures or deformations were observed after clinical use. Higher preparation time was needed during the third use of the instruments for all root canals (p < 0.05). There were no significant differences among the groups in regard to either cyclic fatigue or torsional resistance (p > 0.05). Regarding the roughness measurements, groove depth was higher on new and one- versus two- or three-maxillary-molar-prepared instruments (p < 0.05). It can be concluded that the clinical use of Reciproc instruments increased preparation time and decreased surface roughness. However, clinical use did not affect the cyclic fatigue or torsional resistance of the Reciproc instruments.

Abstract The aim of this randomized clinical trial was to compare the occurrence and intensity of postoperative pain and analgesic intake after root canal treatment, using different root canal sealers. Sixty single-rooted teeth diagnosed with asymptomatic necrosis and apical periodontitis were randomly assigned to 3 experimental groups (n=20), according to the root canal sealer: AH Plus, Endofill or MTA Fillapex. Endodontic treatment was performed in two sessions, and calcium hydroxide was used as the intracanal dressing. Patients were instructed to record pain intensity as none, slight, moderate and severe. Scores from 1 to 4 were attributed to each level of pain after 24 h, 48 h and 7 days. The need for analgesic intake was also recorded. Differences in the incidence of postoperative pain and the need for an analgesic were analyzed using the chi-square test. Differences in pain intensity after treatment were analyzed using the ordinal (linear) chi-square test. No significant differences were detected among the groups in terms of either incidence or intensity of postoperative pain, or need for analgesic intake, at any timepoint (p>0.05). No pain was reported after 7 days. AH Plus, Endofill and MTA Fillapex used for filling root canals resulted in the same rate of postoperative pain and need for analgesic medication.

Abstract The objective of this study was to assess the influence of chlorhexidine (liquid and gel) and zinc oxide in calcium hydroxide (CH) pastes on root pH in simulated external resorption. One hundred human anterior teeth with a single root canal were selected. After decoronation and root canal instrumentation, the specimens were divided into 4 experimental groups and 1 control group (without intracanal paste): CH + saline (CH+S), CH + 2% chlorhexidine liquid (CH+ CHX), CH + 2% chlorhexidine gel (CH+ CHXg), and CH + 2% chlorhexidine gel + zinc oxide (CH+ CHXg+ZnO). pH was measured using a microelectrode at 3 and 24 h, and 1, 2, 3, and 4 weeks after inserting intracanal pastes. Data were analyzed statistically using an ANOVA and Tukey’s test (p < 0.05). The CH+CHXg+ZnO group had the highest pH values throughout (p<0.05). The CH+S and CH+ CHX groups had the highest pH values after 1 week and the CH+ CHXg group after 2 weeks. CH+ CHXg maintained the highest pH until the fourth week compared with CH+ CHX (p < 0.05). The control group remained at a neutral pH at all evaluated times. It can be concluded that chlorhexidine solution or gel maintained the alkaline pH of CH, and chlorhexidine gel allowed a slower decrease in pH over time. CH+ CHXg+ZnO showed the highest pH values and was an effective intracanal medication for maintaining alkaline root pH in the area of resorption.

Resumo O presente estudo comparou o efeito da utilização de uma irrigação intermediária com água destilada usando a irrigação convencional, a microcânula EndoVac ou o sistema Self-Adjusting File (SAF) na prevenção de formação da smear-layer química (SLQ). Trinta pré-molares humanos foram utilizados. Os canais foram preparados com sistema Reciproc e irrigados com NaOCl a 5,25%. Após o preparo químico mecânico, as amostras foram divididas em 3 grupos (n=10) de acordo com o protocolo de irrigação intermediária com água destilada utilizado: irrigação convencional, a microcânula EndoVac ou SAF. Utilizou-se uma lavagem final com solução de clorexidina a 2% e a microscopia electrónica de varredura foi utilizada para avaliar a eficácia dos protocolos. Dois avaliadores calibrados atribuíram escores de acordo com a presença ou ausência de SLQ nas paredes do canal radicular nos terços coronal, médio e apical, como a seguir: (1) sem SLQ; (2) pequenas quantidades de SLQ; (3) SLQ moderada e (4) muita SLQ. As diferenças entre protocolos foram analisadas com testes de Kruskal-Wallis e Mann-Whitney U. Os testes Friedman e Wilcoxon foram utilizados para comparação entre cada terço do canal radicular. SAF resultou em menor formação de SLQ quando comparado com a irrigação convencional e a microcânula EndoVac (p<0,05). Quando os terços dos canais radiculares foram analisados, os grupos irrigação convencional e microcânula EndoVac apresentaram menor formação de SLQ nos terços coronal e médio em relação ao terço apical (p<0,05). No grupo SAF, não houve diferença entre os terços (p>0,05). Dentro dos resultados do presente estudo, pode-se concluir que um fluxo intermediário de água destilada, administrado pelo sistema SAF resultou em melhor redução da formação de SLQ durante o preparo químico mecânico.

Abstract This study compared the effect of intermediate flush with distilled water delivered by conventional irrigation, EndoVac microcannula or Self-Adjusting File (SAF) system in the prevention of chemical smear layer (CSL) formation. Thirty human premolars were used. Canals were prepared with Reciproc system and 5.25% NaOCl. After chemomechanical preparation, samples were divided in 3 groups (n=10) according to the intermediate irrigation protocol with distilled water using: conventional irrigation, EndoVac microcannula or SAF. A final flush with 2% chlorhexidine solution was used and scanning electron microscopy was performed to assess protocol effectiveness. Two calibrated evaluators attributed scores according the presence or absence of CSL on the surface of the root canal walls at the coronal, middle and apical thirds, as follows: (1) no CSL; (2) small amounts of CSL; (3) moderate CSL; and (4) heavy CSL. Differences between protocols were analyzed with Kruskal-Wallis and Mann-Whitney U tests. Friedman and Wilcoxon signed rank tests were used for comparison between each root canal third. SAF resulted in less formation of CSL when compared with the conventional irrigation and EndoVac microcannula (p<0.05). When root canal thirds were analyzed, conventional irrigation and EndoVac groups showed less CSL formation at coronal and middle thirds in comparison to the apical third (p<0.05). In SAF group, there was no difference among the thirds (p>0.05). It may be concluded that an intermediate flush of distilled water, delivered by the SAF system resulted in a better reduction of CSL formation during chemomechanical preparation.

Resumo O objetivo deste estudo clínico foi avaliar a relação entre a demora na procura por tratamento e o desenvolvimento de reabsorções inflamatórias externas em dentes luxados com ápice fechado. A amostra desta pesquisa foi constituída por 67 pacientes que apresentaram 133 dentes traumatizados, dos quais 56 foram acometidos por luxação extrusiva, 69 por luxação lateral e 8 por luxação intrusiva, proservados por no mínimo 24 meses. Foi registrado o tempo decorrido entre a data do trauma e o primeiro atendimento. Verificou-se a ocorrência de necrose pulpar e reabsorções inflamatórias externas em cada tipo de traumatismo. O Teste Exato de Fisher foi aplicado para verificar a influência da data do atendimento inicial e o desenvolvimento de reabsorções inflamatórias externas em cada tipo de luxação e o teste de Odds Ratio foi aplicado para verificar o risco do desenvolvimento de reabsorções inflamatórias externas em função da demora na procura por tratamento. Os resultados revelaram que a necrose pulpar foi verificada em 105 dentes luxados (78,9%) e a reabsorção inflamatória externa foi verificada em 17.8% das luxações extrusivas (10), sendo 15,9% das luxações laterais (11) e 25% das luxações intrusivas (2). A demora na procura por tratamento influenciou o desenvolvimento de reabsorções infamatórias externas nas luxações laterais (p=0,0174). Os pacientes que procuraram tratamento após 45 dias da data do trauma apresentaram 3,4 vezes mais chance de desenvolver reabsorção inflamatória externa do que os pacientes que procuraram tratamento logo após o traumatismo. Conclui-se que o tratamento tardio após a ocorrência do traumatismo pode prejudicar o prognóstico e favorecer o desenvolvimento de reabsorções inflamatórias externas em dentes luxados com ápice fechado.

Abstract This clinical study aimed to evaluate the relationship of the delay between dental trauma and the initial attendance to the development of external inflammatory root resorption in permanent teeth affected by severe luxation. Sixty-seven patients, aged between 11 and 56 years, presenting 133 injured teeth with closed apex (56 extrusive luxation, 69 lateral luxation and 8 intrusive luxation) were followed up for a minimum of 24 months. The time elapsed between dental trauma and the initial attendance was recorded. The presence of necrotic pulp and external inflammatory resorption for each type of trauma was verified. Fisher’s exact test was used to verify the influence of the initial attendance date at the Dental Trauma Center and the development of inflammatory resorption (p<0.05). The odds ratio was used to check the risk of developing external inflammatory resorption due to delay in seeking treatment. Pulp necrosis was observed in 105 teeth (78.9%) and external inflammatory resorption was detected in 17.8% cases of extrusive luxation (10 teeth), 15.9% of lateral luxation (11 teeth) and 25% of intrusive luxation (2 teeth). For lateral luxation, extended delay between the date of injury and initial attendance influenced the occurrence of external inflammatory resorption (p=0.0174). Patients who began treatment 45 days after the injury were 3.4 times more likely to develop external inflammatory resorption than patients who sought treatment after the trauma. Treatment late after the occurrence of dental trauma can impair the prognosis and result in the development of external inflammatory resorption in luxated teeth.

Resumo O objetivo do presente estudo foi verificar os efeitos citotóxicos de longo prazo da MTA Fillapex e comparar com os do AH Plus. Solubilidade e pH também foram avaliados. Osteoblastos humanos foram incubados com elutos de amostras frescas de AH Plus e MTA Fillapex, e com elutos dos mesmos espécimes pelas 4 semanas seguintes. O pH foi avaliado a cada semana. Um ensaio multiparamétrico de viabilidade celular foi realizado. Para solubilidade foi utilizada metodologia ISO. Os resultados foram analisados por ANOVA, complementada com o pós-teste de Tukey (p<0,05). Nenhuma diferença significativa foi encontrada entre os materiais frescos quando avaliados em relação a citotoxicidade (p>0,05). Depois de uma semana, o AH Plus tornou-se não-citotóxico em todos os três parâmetros avaliados. Por outro lado, MTA Fillapex permaneceu citotóxico durante todo o período experimental (p<0,05). A solubilidade do AH Plus foi significativamente menor do MTA Fillapex para todos os períodos avaliados (p>0,05). O pH da AH Plus foi significativamente menor do que o MTA Fillapex na segunda e na terceira semana (p<0,05). Nos outros períodos testados não houve diferença estatística. Em conclusão, o MTA Fillapex permaneceu citotóxico após 4 semanas e a sua citotoxicidade pode estar relacionada à elevada solubilidade deste material.

Abstract The aim of the present study was to verify the long-term cytotoxic effects of the MTA Fillapex and to compare them with AH Plus. Dissolution rate and pH were also evaluated. Human osteoblast cells were incubated with elutes of fresh specimens from AH Plus and MTA Fillapex, and with elutes of the same specimens for 4 successive weeks. Elute's pH was evaluated at each time point. A multiparametric cell viability assay was performed. For dissolution rate, ISO methodology was used. The results were analyzed by one-way analysis of variance, complemented with the Tukey post-test (p<0.05). No significant difference was found among the materials when fresh mixed (p>0.05). After 1 week, AH Plus became non-cytotoxic on all three evaluated parameters. Conversely, MTA Fillapex remained severely and mildly cytotoxic over the entire experimental period (p<0.05). The dissolution rate of AH Plus was significantly lower than MTA Fillapex at all time points (p>0.05). The pH of AH Plus was significantly lower than MTA Fillapex at the second and third week (p<0.05). In the other tested time points no statistical difference was observed. In conclusion, MTA Fillapex remained cytotoxic after 4 weeks and its cytotoxicity may be related to the high dissolution rate of this material.

O objetivo do presente estudo foi avaliar e comparar a dor pós-operatória após a instrumentação foraminal usando NaOCl 5,25% ou gel de CHX 2% em dentes não vitais unirradiculares após instrumentação reciprocante. Sessenta e dois voluntários, apresentando um único canal radicular diagnosticado com necrose assintomática e periodontite apical, foram randomizados em dois grupos experimentais de acordo com o protocolo de irrigação (ou seja, grupos de NaOCl 5,25% e CHX gel 2%). O tratamento endodôntico foi realizado em uma única visita sob instrumentação reciprocante com instrumentação foraminal. Os voluntários foram instruídos a registrar a intensidade da dor. Escores de 1-4 foram atribuídos a cada tipo de dor após 24, 48 e 72 h. Testes de Kolmogorov-Smirnov e t de Student foram utilizados para determinar diferenças significativas em p<0,05. Em média, o percentual de pacientes que teve nenhumaou leve dor após 24, 48 ou 72 h foi de 77.4%, 88.7% e 95.1%, respectivamente. Não foi encontrada diferença de idade estatisticamente significante entre os grupos (p>0,05, teste t de Student). A dor pós-operatória não apresentou diferença estatisticamente significativa em qualquer período de observação ao usar NaOCl 5,25% ou CHX gel 2% (p>0,05). Além disso, não foi observada diferença significativa no número médio de comprimidos analgésicos utilizados entre os grupos (p>0,05). O uso de NaOCl 5,25% ou CHX gel 2% resultou na mesma dor pós-operatória. Portanto, pode-se inferir que a escolha do irrigante não tem relação com um acompanhamento a curto prazo em relação a dor pós-operatória.

The aim of the present study was to evaluate and compare postoperative pain after foraminal instrumentation using 5.25% sodium hypochlorite (NaOCl) or 2% chlorhexidine (CHX) gel irrigation protocol in nonvital single-rooted teeth after reciprocating instrumentation. Sixty-two volunteers presenting a single root canal diagnosed with asymptomatic necrosis and apical periodontitis were randomized into 2 experimental groups regarding the irrigation protocol (ie, 5.25% NaOCl and 2% CHX gel groups). Endodontic treatment was performed in a single session under reciprocating instrumentation with foraminal instrumentation. Volunteers were instructed to record pain intensity. Scores from 1 to 4 were attributed to each kind of pain after 24, 48, and 72 h. Kolmogorov-Smirnov and Student´s t tests were used to determine significant differences at p<0.05. On average, the percentage of patients that had no or mild pain after 24, 48 or 72 h was 77.4%, 88.7% and 95.1%, respectively. No statistically significant age difference was found between the groups (p>0.05, Student´s t test). Postoperative pain showed no statistically significant difference at any observation period when using 5.25% NaOCl or 2% CHX gel (p>0.05). Moreover, no significant difference was observed in the mean number of analgesic tablets used between the groups (p>0.05). In conclusion, the use of 5.25% NaOCl or 2% CHX gel resulted in the same postoperative pain. Therefore, it can be inferred that irrigant choice has no relation with short-term follow up regarding postoperative pain.

The search for new instruments to promote an appropriate cervical preparation has led to the development of new rotary instruments such as TripleGates. However, to the best of the authors' knowledge, there is no study evaluating TripleGates effect on the “risk zone” of mandibular molars.Objectives: The aim of this study was to evaluate the effects of a crown-down sequence of Gates-Glidden and TripleGates burs on the remaining cervical dentin thickness and the total amount of dentin removed from the root canals during the instrumentation by using cone beam computed tomography. The number of separated instruments was also evaluated.Material and Methods : Mesial roots of 40 mandibular first molars were divided into 2 equal groups: crown-down sequence of Gates-Glidden (#3, #2, #1) and TripleGates burs. Cervical dentin thickness and canal area were measured before and after instrumentation by using cone beam computed tomography and image analysis software. Student’s t-test was used to determine significant differences at p<0.05.Results : No significant differences (p>0.05) were observed between the instruments, regarding the root canal area and dentin wall thickness.Conclusion : Both tested instruments used for cervical preparation were safe to be used in the mesial root canal of mandibular molars.

Phosphoric acid has been suggested as an irrigant due to its effectiveness in removing the smear layer.Objectives: The purpose of this study was to compare the antimicrobial and cytotoxic effects of a 37% phosphoric acid solution to other irrigants commonly used in endodontics.Material and Methods : The substances 37% phosphoric acid, 17% EDTA, 10% citric acid, 2% chlorhexidine (solution and gel), and 5.25% NaOCl were evaluated. The antimicrobial activity was tested against Candida albicans, Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Actinomyces meyeri, Parvimonas micra, Porphyromonas gingivalis, and Prevotella nigrescensaccording to the agar diffusion method. The cytotoxicity of the irrigants was determined by using the MTT assay.Results : Phosphoric acid presented higher antimicrobial activity compared to the other tested irrigants. With regard to the cell viability, this solution showed results similar to those with 5.25% NaOCl and 2% chlorhexidine (gel and solution), whereas 17% EDTA and 10% citric acid showed higher cell viability compared to other irrigants.Conclusion : Phosphoric acid demonstrated higher antimicrobial activity and cytotoxicity similar to that of 5.25% NaOCl and 2% chlorhexidine (gel and solution).

Aim: To evaluate the foraminal transportation during foraminal enlargement after manual instrumentation with stainless steel files, preparation with the Mtwo system and Reciproc R25 file. Methods: Thirty roots were selected, divided in three groups and prepared in accordance with the different instrumentation systems: Hand Files (HF); Mtwo system (MS); and Reciproc system (RS). All groups were prepared with the instrumentation level 1 mm beyond the apex. Photomicrographs were performed using scanning electron microscopy, to record the foraminal anatomy before and after instrumentation. Data were analyzed using ANOVA followed by Tukey's test with a significance level of 5%. Results: The group instrumented with hand files showed higher foraminal transportation when compared to the Mtwo and Reciproc groups (p<0.05). Reciproc group showed lower transportation when compared to the Mtwo group (p<0.05). Conclusions: The stainless steel files caused significant foraminal transportation, while Reciproc system showed safe apical preparation, with little transportation.

Objectives The aim of the present study was to investigate the effects of root canal sealers on the cytotoxicity of 3T3 fibroblasts during a period of 5 weeks. Material and Methods Fibroblasts (3T3, 1×105 cells per well) were incubated with elutes of fresh specimens from eight root canal sealers (AH Plus, Epiphany, Endomethasone N, EndoREZ, MTA Fillapex, Pulp Canal Sealer EWT, RoekoSeal and Sealapex) and with elutes of the same specimens for 5 succeeding weeks after immersing in simulated body fluid. The cytotoxicity of all root canal sealers was determined using the MTT assay. Data were analyzed using ANOVA and Tukey's test. Results RoekoSeal was the only sealer that did not show any cytotoxic effects (p<0.05). All the other tested sealers exhibited severe toxicity initially (week 0). MTA Fillapex remained moderately cytotoxic after the end of experimental period. Toxicity of the other tested sealers decreased gradually over time. The evaluated root canal sealers presented varying degrees of cytotoxicity, mainly in fresh mode. Conclusions RoekoSeal had no cytotoxic effect both freshly mixed and in the other tested time points. MTA Fillapex was associated with significantly less cell viability when compared to the other tested root canal sealers.