Resumo Este relato de caso descreve o tratamento e acompanhamento de um molar inferior em uma jovem de 18 anos com cisto periapical. Assim, torna-se importante saber quais opções devemos tomar diante de uma situação clínica que não podemos resolver pelos métodos convencionais, e quais técnicas e abordagens temos para alcançar o sucesso do tratamento. Este caso mostrou o plano de tratamento e acompanhamento, por meio de imagens de tomografia computadorizada de feixe cônico (TCFC), de um molar inferior previamente tratado com grande abscesso periapical e lesão cística, no qual, a primeira abordagem do plano de tratamento foi fazer o retratamento endodôntico. Durante o preparo químico-mecânico a presença de exsudato purulento intracanal permanente impossibilitou a secagem dos canais, impedindo a obturação do sistema de canais radiculares. Devido a essa situação clínica, foi realizada abordagem cirúrgica com a intenção de reduzir esse exsudato permanente e executar uma técnica de descompressão. Após um ano de acompanhamento, os achados clínicos e radiográficos indicaram processo de reparo.

Abstract This case describes the treatment and follow-up of a mandibular molar in an 18-year-old female with a periapical cyst. Thus, it becomes important to know which options should we take when faced with a clinical situation that we cannot resolve through conventional methods, and which techniques and approaches we have to achieve treatment success. This case showed the treatment plan and follow-up, by the use of CBCT images, from a previously treated mandibular molar with a large periapical abscess and cystic lesion, in which, the first treatment plan approach was to make the endodontic retreatment. During the chemo-mechanical preparation the presence of permanent intracanal purulent exudate made it impossible to dry the canals, impeding obturation of the root canal system. Due to this clinical situation, a surgical approach was performed with the intention of reduce this permanent exudate and to execute a decompression technique. Clinical findings, periapical radiographs and cone beam computed tomographic, indicated almost complete resolution of the radiolucency, after a one-year follow-up.

Abstract Objectives This study assessed the incidence and variability features of root canals system (RCS) and their ramifications according to Pucci & Reig (PR) (1944) and the American Association of Endodontists (AAE) (2017) by micro-computed tomography (μCT). Methodology 500 representative extracted human teeth of each tooth group (n=50) (maxillary/mandibular central and lateral incisors, canines, first and second premolars and molars) were scanned by μCT with a resolution of 26.70 μm. The reconstructed cross-sections images and the visualization of the continuous slices in the transversal axis were performed using DataViewer software. RCS were classified according to Pucci & Reig (main canal, collateral canal, lateral canal, secondary canal, accessory canal, intercanal, recurrent canal) and AAE (main canal, accessory canal, lateral canal). The apical deltas were assessed for both classifications. The prevalence of apical deltas was evaluated using the Chi-squared test (p<0.05). Results According to PR, a higher incidence of lateral canals was observed in maxillary canines (10%), central incisors (8%) and first premolars (6%). Using AAE, the highest incidence of lateral canals was observed in the mandibular first premolars (85%), first and second molars (84%), lateral incisors (67%), canines (59%), and in maxillary first premolars (52%). Regarding accessory canals, the PR showed a frequency in 2% of the maxillary lateral incisors and maxillary and mandibular first premolars and 3% of mandibular first and second molars. On the other hand, the AAE showed the highest incidence of accessory canals in 86% of the maxillary first premolars, 71% in mandibular lateral incisors, 69% in mandibular first premolars, 65% in mandibular canines, and 56% in maxillary canines. The PR showed the lowest incidence of apical deltas for all dental groups when compared with AAE (p=0.004). Interestingly, distal canals in maxillary molars showed a significant discrepancy between classifications (p=0.027). Conclusions μCT enabled accurately describing the RC system and related ramifications, adding to the PR and AAE classifications, with some discrepancies reported for maxillary molars. Clinical Relevance This μCT study enabled a thorough description of the variability among root canals and their ramifications, including clinically relevant details on the presence and location of lateral canals and accessories in all human tooth groups, beyond the currently existing classification systems.

Abstract The aim of this study was to evaluate the influence of radiation therapy on root canal sealer push-out bond strength (BS) to dentin and the sealer/dentin interface after different final irrigation solutions (NaOCl, EDTA, and chitosan). Sixty-four maxillary canines were distributed into two groups (n=30): non-irradiated and irradiated with 60 Gy. Canals were prepared with Reciproc-R50 and subdivided (n=10) for final irrigation (NaOCl, EDTA, chitosan) and filled. Three dentin slices were obtained from each root third. The first slice of each third was selected for BS evaluation, and the failure mode was determined by stereomicroscopy. SEM analysis of the sealer-dentin interface was performed in the remaining slices. Two-way ANOVA and Tukey's tests (α=0.05) were used. Lower BS (P<0.0001) was obtained after irradiation (2.07±0.79 MPa), regardless of the final irrigation solution used. The NaOCl group (P<0.001) had the lowest BS in the irradiated (1.68±0.72) and non-irradiated (2.39±0.89) groups, whereas the EDTA (irradiated: 2.14±0.77 and non-irradiated: 3.92±1.54) and chitosan (irradiated: 2.37±0.73 and non-irradiated: 3.51±1.47) groups demonstrated a higher BS (P<0.05). The highest values were observed in the coronal third (3.17±1.38) when compared to the middle (2.74±1.36) and apical ones (2.09±0.97)(P<0.0001). There were more cohesive failures and more gaps in irradiated specimens, regardless of the final solution. The present study showed that radiation was associated with a decrease in BS, regardless of the final solution used, whereas chitosan increased BS in teeth subjected to radiation therapy.

Abstract: This literature review has critically analyzed the published research related to the biomechanical preparation of root canals with three-dimensional analysis using micro-computed tomography (micro-CT). In December 2017, six databases (PubMed, Cochrane, Web of Science, Embase, Scopus, and Science Direct) were accessed using keywords to find articles including the use of the micro-CT analysis in biomechanical root canal preparation. There were 60 full articles that were selected, which were screened and read by two authors. The research that was reviewed and analyzed included root canal anatomy and sample selection, changes in canal shape and untouched canal areas, canal transportation and centering ability, and kinematics (motion). Of the studies selected, 49.18% discussed anatomical characteristics, with 54.1% of these studies describing mesial roots of mandibular molars with moderate curvature. Only 35% used a stratified distribution based on root canal system morphology and quantitative data obtained by micro-CT. The analysis of canal transportation and centering ability showed that transport values in the apical third exceeded the critical limit of 0.3 mm in mesial roots of mandibular molars with moderate curvature, especially in the groups in which a reciprocating system was used. In relation to kinematics, 91.70% of the reviewed studies evaluated continuous rotating instruments, followed by reciprocating rotation (38.33%), vibratory (15%), and the adaptive kinematics, which was in only 8.33%. The reciprocating kinematics was associated with higher canal decentralization and transportation indexes, as well as a greater capacity for dentin removal and debris accumulation. This literature review showed that the anatomy, the type of design and kinematics of instruments, and the experimental design are factors that directly influence the quality of biomechanical preparation of root canals analyzed in a qualitative and quantitative manner by micro-CT.

Resumo O objetivo deste estudo foi avaliar a morfologia de 70 pré-molares inferiores com depressões radiculares (DR) usando a microtomografia. Os dentes foram escaneados e avaliados quanto à morfologia das raízes e canais radiculares, bem como o comprimento, profundidade, frequência e localização das DR. O volume, a área de superfície e o Structure Model Index (SMI) dos canais foram mensurados no comprimento total da raiz. Parâmetros bidimensionais e orifícios do canal foram avaliados a 1, 2 e 3 mm do forame apical. O número de canais acessórios, a espessura dentinária e a aparência transversal do canal em diferentes níveis de raiz também foram registrados. A expressão de sulcos profundos foi observada em 21,42% da amostra. Os comprimentos médios de raiz e DR foram de 13,43 mm e 8,5 mm, respectivamente, enquanto a profundidade das DR variou de 0,75 a 1,13 mm. O volume médio do canal, a área superficial e o SMI foram de 10,78 mm3, 58,51 mm2 e 2,84, respectivamente. O delta apical estava presente em 4,35% da amostra e os canais acessórios foram observados principalmente nos terços médio e apical. Os parâmetros bidimensionais indicaram canais radiculares com secção oval e alta frequência de divisões canal principal (87,15%). A configuração Tipo V do canal radicular foi a mais prevalente (58,57%). A presença de canais em forma de C foi observada em 13 pré-molares (18,57%), enquanto a espessura dentinária variou de 1,0 a 1,31 mm. Os sulcos radiculares nos primeiros pré-molares inferiores foram associados à ocorrência de várias complexidades anatômicas, incluindo canais em forma de C e múltiplas divisões do canal principal.

Abstract The aim of this study was to evaluate morphological features of 70 single-rooted mandibular first premolars with radicular grooves (RG) using micro-CT technology. Teeth were scanned and evaluated regarding the morphology of the roots and root canals as well as length, depth and percentage frequency location of the RG. Volume, surface area and Structure Model Index (SMI) of the canals were measured for the full root length. Two-dimensional parameters and frequency of canal orifices were evaluated at 1, 2, and 3 mm levels from the apical foramen. The number of accessory canals, the dentinal thickness, and cross-sectional appearance of the canal at different root levels were also recorded. Expression of deep grooves was observed in 21.42% of the sample. Mean lengths of root and RG were 13.43 mm and 8.5 mm, respectively, while depth of the RG ranged from 0.75 to 1.13 mm. Mean canal volume, surface area and SMI were 10.78 mm3, 58.51 mm2, and 2.84, respectively. Apical delta was present in 4.35% of the sample and accessory canals were observed mostly at the middle and apical thirds. Two-dimensional parameters indicated an oval-shaped cross-sectional appearance of the root canal with a high percentage frequency of canal divisions (87.15%). Canal configuration type V (58.57%) was the most prevalent. C-shaped configuration was observed in 13 premolars (18.57%), whereas dentinal thickness ranged from 1.0 to 1.31 mm. Radicular grooves in mandibular first premolars was associated with the occurrence of several anatomical complexities, including C-shaped canals and divisions of the main root canal.

Abstract: The aim of this study was to compare two irrigation techniques and four devices for endodontic sealer placement into the dentinal tubules. Ninety-nine single-rooted human teeth were instrumented and allocated to either the control (CO) (n=11) or experimental groups according to the irrigation method: syringe and NaveTip needle (NT) (n=44), and EndoActivator (EA) (n=44). These groups were subdivided according to sealer placement into K-File (KF), lentulo spiral (LS), Easy Clean (EC), and EndoActivator (EA) subgroups. Moreover, the distances of 5 mm and 2 mm from the apex were analyzed. The teeth were obturated with AH Plus and GuttaCore X3. Analyses were performed by scanning electron microscopy associated to cathodoluminescence. The percentage and maximum depth of sealer penetration were measured. Data were evaluated by three-way analysis of variance (ANOVA) and Games-Howell test (p<0.05). EA was superior to NT in percentage of sealer penetration. EC was significantly superior to EA (subgroup) for sealer penetration, and both improved the percentage of sealer penetration when compared to LS. Better sealer penetration was observed at the distance of 5 mm from the apex. Sealer penetration into the dentinal tubules was significantly improved by sonic irrigant activation.

Resumo A relação do forame principal com o ápice anatômico da raiz tem sido objeto de vários estudos. Embora estejam anatomicamente próximos, eles raramente coincidem, e a sua distância pode variar de acordo com a idade ou o tipo de dente, oscilando entre 0,2 e 3,0 mm. O objetivo deste artigo é relatar que a saída foraminal do canal mediano (MMC), presente na raiz mesial de molares inferiores, pode apresentar variações significativas, atingindo distâncias acima de 3 mm do ápice anatômico. Vinte e cinco primeiros molares inferiores com MMC foram escaneados (resolução de 9,9 mm) e a distância do forame principal ao ápice anatômico avaliada. Em geral, a distância mostrou variações consideráveis; no entanto, em 3 espécimes esta distância ficou acima de 3 mm. Este estudo teve como objetivo relatar que a saída do forame principal de canais medianos de primeiros molares inferiores pode apresentar variações consideráveis, podendo atingir distâncias maiores do que as relatadas previamente na literatura.

Abstract The relationship of the main foramen to the anatomic root apex has been the subject of several studies. Although they are anatomically close, they rarely coincide, and their distance can vary according to age or tooth type, ranging from 0.2 to 3.0 mm. The aim of this short communication was to evaluate the distance between the main foramen of independent middle mesial canals (MMCs) and the anatomical mesial root apex of mandibular first molars using the micro-computed tomography. Twenty-five mandibular first molars with MMCs were scanned (resolution of 9.9 µm), and the distance from its main foramen to the anatomical apex was evaluated. Overall, the distance ranged from 0.2 to 2.4 mm; however, in 3 specimens the distance was greater than 3 mm. This report demonstrates that the exit of the main foramen of the MMC varies considerably and could approach a substantial distance from the anatomical apex greater than previously reported in the literature.

OBJECTIVE: This study assessed the muscular activity during root canal preparation through kinematics, kinetics, and electromyography (EMG). MATERIAL AND METHODS: The operators prepared one canal with RaCe rotary instruments and another with Flexo-files. The kinematics of the major joints was reconstructed using an optoelectronic system and electromyographic responses of the flexor carpi radialis, extensor carpi radialis, brachioradialis, biceps brachii, triceps brachii, middle deltoid, and upper trapezius were recorded. The joint torques of the shoulder, elbow and wrist were calculated using inverse dynamics. In the kinematic analysis, angular movements of the wrist and elbow were classified as low risk factors for work-related musculoskeletal disorders. With respect to the shoulder, the classification was medium-risk. RESULTS: There was no significant difference revealed by the kinetic reports. The EMG results showed that for the middle deltoid and upper trapezius the rotary instrumentation elicited higher values. The flexor carpi radialis and extensor carpi radialis, as well as the brachioradialis showed a higher value with the manual method. CONCLUSION: The muscular recruitment for accomplishment of articular movements for root canal preparation with either the rotary or manual techniques is distinct. Nevertheless, the rotary instrument presented less difficulty in the generation of the joint torque in each articulation, thus, presenting a greater uniformity of joint torques.

The aim of this study was to evaluate the influence of different restorative procedures on the fracture resistance of endodontically treated teeth submitted to intracoronal bleaching. Fifty upper central incisors were distributed into 5 groups: GI - healthy teeth; GII - endodontically treated teeth sealed with Coltosol; GIII - endodontically treated teeth bleached and sealed with Coltosol; GIV - endodontically treated teeth bleached and restored with composite resin; and GV - endodontically treated teeth bleached and restored with a fiberglass post and composite resin. In the bleached specimens, a cervical seal was made prior to bleaching with 38% hydrogen peroxide. The gel was applied on the buccal surface and in the pulp chamber, and was then light-activated for 45 s. This procedure was repeated three times per session for four sessions, and each group was submitted to the restorative procedures described above. The specimens were submitted to fracture resistance testing in a universal testing machine. There were statistically significant differences among the groups (p < 0.05). The mean value found for GIII was the lowest (0.32 kN) and was significantly different from the values found for GI (0.75 kN), GII (0.67 kN), GIV (0.70 kN), and GV (0.72 kN), which were not significantly different from each other (p > 0.05). The restorative procedures using composite resin were found to successfully restore the fracture resistance of endodontically treated and bleached teeth.

OBJETIVO: Avaliou-se in vitro a resistência à fratura de raízes com pinos metálicos fundidos e de fibra de vidro, variando sua configuração geométrica. METODOLOGIA: Cinquenta incisivos centrais superiores tratados endodonticamente foram incluídos em resina acrílica. Dez receberam apenas preparo coronário (controle) e quarenta tiveram coroas seccionadas e raízes incluídas em resina (deixando 4 mm cervicais). Distribuiu-se os espécimes em 5 grupos: controle, pino metálico cilíndrico, metálico cônico, pino de fibra de vidro cilíndrico e cônico. Submeteram-se os corpos-de-prova a ensaio de compressão, até ocorrer a fratura. RESULTADOS: A ANOVA indicou diferença significante entre os grupos (P<.05) e no teste de Tukey-Kramer´s o controle (867±243 N) apresentou os maiores valores de resistência à fratura, sendo similar ao grupo do pino de fibra cilíndrico (711±180 N). Não houve diferença significante entre os pinos metálicos cilíndricos (435±245 N) ou cônicos (585±164 N) e os de fibra cônicos (453±112 N). Os grupos dos pinos de fibra cilíndricos (711±180 N) e pinos metálicos cônicos (585±164 N) apresentaram valores intermediários e não foram diferentes entre si. CONCLUSÃO: Pinos de fibra de vidro são uma alternativa viável ao pino metálico fundido cilíndrico e cônico. Os pinos de fibra cilíndricos aumentaram a resistência à fratura dos incisivos tratados endodonticamente.

PURPOSE: To evaluate the in vitro fracture resistance of roots with glass-fiber and metal dowels with different designs. METHODS: Fifty-endodontically treated maxillary central incisors were embedded in acrylic resin. Ten of them received only the coronary preparation, and the remaining forty were embedded (except for 4mm of the cervical area) after removing the clinical crowns. Specimens were divided into five groups (n=10): control (teeth with only coronary preparation), cylindrical cast dowel, conical cast dowel, cylindrical glass-fiber dowel and conical glass-fiber dowel. Specimens were subjected to an increasing compressive load (N) until fracture. RESULTS: ANOVA indicated significant difference (P<.05) among the groups, and the Tukey-Kramer´s test identified these differences. The control group (867±243 N) presented the highest values and was statistically similar to cylindrical glass-fiber dowel group (711±180 N). There is no significant difference among the metal dowel cylindrical (435±245 N) or conical (585±164 N) group and conical glass-fiber dowel (453±112 N). Cylindrical glass-fiber dowel (711±180 N) and conical cast dowel and core (585±164 N) groups had intermediate values and did not differ from each other. CONCLUSIONS: Cylindrical glass fiber dowels represent a viable alternative to the cast-metal dowel cylindrical or conical. Cylindrical glass fiber dowels also increase endodontically treated incisors' resistance to fracture.

The cleaning capacity of Hero 642 nickel-titanium files, complemented by the Hero Apical instruments in flattened roots, was determined by histological analysis, considering the area of action of the instruments on the coronal walls and the presence of remaining debris. Twenty-four single-canal, human mandibular incisors were divided into three groups and prepared as follows: GI, instrumented with Hero 642 NiTi files 30/.06, 25/.06, 20/.06, 25/.06, and 30/.06; GII, instrumented as GI followed by Hero Apical size 30/.06; GIII, instrumented as GI followed by Hero Apical sizes 30/.06 and 30/.08, then returning to 30/.06 with pendulum movements. The apical thirds were prepared for histological processing, analyzed at 40× magnification and the images were examined morphometrically. Statistical analysis showed that GIII presented the best results for removing debris (5.22% ± 4.13), with more contact between the instruments and the root canal walls (19.31% ± 0.15). This differed statistically from GI (14.04% ± 4.96 debris removal, with 42.96% ± 7.11 instrument contact) and GII (12.62% ± 5.76 debris removal, with 35.01% ± 0.15 instrument contact). Root canal preparation with Hero 642, complemented by Hero Apical instruments (30/.06 and 30/.08, then re-instrumented with Hero Apical 30/.06 using pendulum movements), was more efficient for debris removal and allowed more contact of the instruments with the root canal walls. GII presented the worst results.

Este estudo in vitro comparou a resistência à remoção por tração de núcleos metálicos fundidos em liga de Cu-Al (Goldent-LA) cilíndricos, jateados, de comprimento constante igual a 9 mm, cimentados com cimento de fosfato de zinco e com três diferentes diâmetros: 0,9 mm, 1,3 mm e 1,7 mm. Trinta e seis caninos superiores hígidos tiveram suas coroas seccionadas, sendo as raízes incluídas em blocos de resina acrílica, e os canais, tratados endodonticamente. Os dentes foram divididos em três grupos para serem preparados e padronizados com o auxílio de um paralelômetro com as seguintes brocas: Grupo 1 - Largo nº 2; Grupo 2 - Largo nº 4; Grupo 3 - Largo nº 6. Os núcleos foram moldados com resina acrílica ativada quimicamente e, após a fundição, foram jateados e tiveram as suas dimensões conferidas com um paquímetro digital. Após a cimentação, os corpos-de-prova foram armazenados em água destilada durante 7 dias, em estufa a 37ºC e, posteriormente, submetidos a teste de tração em uma máquina universal de ensaios Instron 4444. Com a análise estatística dos resultados, pôde-se concluir que não houve diferença estatisticamente significante entre os grupos testados. A variação do diâmetro em núcleos cilíndricos jateados cimentados com fosfato de zinco não afetou a resistência à remoção.

This study compared the resistance to removal by traction of abraded cylindrical metal cast posts of Cu-Al (Goldent-LA). The posts had constant length (9 mm) and three different diameters (0.9, 1.3 and 1.7 mm), and were cemented with zinc phosphate cement. The crowns of 36 sound maxillary canines were sectioned, the roots were immersed in resin blocks and the root canals were endodontically treated. The teeth were divided into three groups to be prepared and standardized with the use of a parallelometer with the following burs: Group 1 - Largo n. 2; Group 2 - Largo n. 4; Group 3 - Largo n. 6. The posts were molded with chemically activated resin and after casting they were abraded and their dimensions were confirmed with a digital caliper. After cementation of the posts in the prepared root canals, the samples were kept at 37ºC in distilled water for 7 days and subsequently submitted to the traction test in a universal testing machine (Instron 4444). The results showed no statistical difference between the groups. Diameter variation (0.9 mm, 1.3 mm and 1.7 mm) in abraded cylindrical posts cemented with zinc phosphate did not affect resistance to removal.

Estudou-se o efeito da solução de EGTA (ácido bis(2-aminoetil) etilenoglicol-N,N,N',N'-tetraacético) a 1, 3 e 5% sobre a microdureza da dentina radicular, no terço cervical de dentes humanos. Utilizaram-se 5 incisivos centrais superiores recém-extraídos. Os dentes foram seccionados transversalmente na junção esmalte/cemento e as coroas foram desprezadas. As raízes foram incluídas em blocos de resina acrílica de rápida polimerização, colocadas em uma máquina de corte e seccionadas transversalmente de 1 em 1 milímetro. O segundo corte do terço cervical da raiz de cada dente foi selecionado para o experimento. Cada corte foi dividido em quatro partes sendo que cada parte foi colocada sobre um disco de acrílico, que servia de suporte para a medida de microdureza. Aplicou-se 50 µl da solução teste durante cinco minutos sobre cada superfície de dentina. Água destilada e deionizada foi utilizada como controle. A microdureza da dentina foi medida em um aparelho de dureza Vickers com 50 gramas de carga e 15 segundos de aplicação. A análise estatística dos resultados mostrou que as 3 soluções quelantes reduziram significantemente a microdureza da dentina quando comparado com a água. As soluções de EGTA a 1, 3 e 5% apresentaram-se estatisticamente diferentes entre si.

The effect of 1%, 3% and 5% EGTA (ethylene glycol-bis-(b-amino-ethyl ether) N,N,N´,N´-tetra-acetic acid) on the microhardness of root dentin of the cervical third of human teeth was studied. Five newly extracted maxillary incisors were sectioned transversely at the cementoenamel junction, and the crowns were discarded. The roots were embedded in blocks of high-speed polymerized acrylic resin and cut transversely into 1-mm sections. The second section of the cervical third of the root of each tooth was sectioned and divided into four parts. Each part was placed on an acrylic disc that was used as a base for microhardness measurement. Fifty microliters of 1% EGTA, 3% EGTA, or 5% EGTA were applied to the dentin surface. Deionized and distilled water was used as control. Dentin microhardness was then measured with a load of 50 g for 15 s. Statistical analysis showed that the three concentrations of the chelating solution EGTA significantly reduced dentin microhardness when compared with water (ANOVA, p<0.01), and that there was a statistically significant difference among the three solutions (Tukey test, p<0.05).