Abstract The aim of this study was to evaluate the effects of proanthocyanidin (PA) and chlorhexidine (CHX) on the bond strength (BS), failure pattern, and resin-dentin interface morphology of the endodontic sealers EndoREZ and AH Plus after 24 h and 6 months of water storage. A total of 120 prepared bovine roots were divided into six groups: AH Plus, CHX+AH Plus, PA+AH Plus, EndoREZ, CHX+EndoREZ, and PA+EndoREZ. Dentin was treated for 1 or 5 min with 2% CHX or 15% PA, respectively. Roots were filled and stored in water for 24 h or 6 months (n = 10). Root slices were subjected to push-out test and scanning electron microscopy (SEM). Data were compared using two-way ANOVA and student's t-test (α = 5%). BS decreased over time for AH Plus and untreated EndoREZ (p < 0.05). At 24 h, AH Plus had higher BS than EndoREZ (p < 0.001), with no differences among treatments for both sealers (p > 0.05). At 6 months, EndoREZ had higher BS values for CHX and PA than control (p < 0.05). AH Plus had higher BS than EndoREZ (p < 0.001), while with CHX or PA, similar BS was observed in both sealers (p > 0.05). Cohesive and mixed failures were observed in all groups. SEM revealed sealer tags in the root dentin. In conclusion, BS decreased with time and AH Plus had higher BS than EndoREZ in untreated dentin; however, CHX or PA enhanced long-term BS of EndoREZ. Overall, dentin treatment affected failure pattern and resin-dentin interface morphology, particularly for EndoREZ.

Resumo Irrigantes para canais radiculares são usados para minimizar os efeitos negativos da camada de smear na retenção do cimento obturador. O objetivo deste estudo foi avaliar a eficácia da agitação do ácido etilenodiaminotetracético a 17% (EDTA) com ultrassom, Nd:YAG 1064-nm e laser diodo 980-nm na retenção de um cimento obturador à base de resina epóxica nas paredes do canal radicular. Quarenta dentes bovinos unirradiculares foram instrumentados com o sistema rotatório ProTaper e divididos em quatro grupos de acordo com o protocolo de irrigação final (n = 10): (1) EDTA 17% (controle); (2) EDTA 17% com agitação ultrassônica por 50-s; (3) EDTA 17% com agitação com laser diodo (2-W) por 50-s; e (4) EDTA 17% com agitação com laser Nd:YAG (1,5-W) por 50-s. Após obturação endodôntica com cone principal F5 e cimento Sealer 26, as raízes foram seccionadas nos terços radiculares cervical, médio e apical para obtenção de slices de 1,5-mm. Testes de push-out foram realizados utilizando uma máquina universal de ensaios com velocidade de carga de 1 mm/min. Os dados foram analisados utilizando os testes two-way ANOVA e Tukey's (α=0,05). Os terços radiculares apicais tiveram força de adesão significantemente maior que os terços cervical e médio (p<0,05). EDTA com Nd:YAG 1064-nm ou laser diodo 980-nm apresentaram os maiores valores de força de adesão e foram significantemente diferentes do EDTA com agitação ultrassônica e EDTA apenas (p < 0,05). Falhas adesivas foram predominantes apenas no grupo EDTA. Falhas mistas foram predominantes em todos os grupos de agitação. A agitação do EDTA com Nd:YAG 1064-nm e laser diodo 980-nm aumentou a força de adesão do cimento à base de resina epóxica às paredes do canal radicular comparado com a obtida com EDTA apenas ou EDTA com agitação ultrassônica.

Abstract Root canal irrigants are used to minimize the negative effects of smear layer on endodontic sealer retention. The aim of this study was to evaluate the efficacy of agitation of 17% ethylenediaminetetraacetic acid (EDTA) with ultrasonic, 1064-nm Nd:YAG and 980-nm diode laser on the retention of an epoxy-based sealer to the root canal walls. Forty single-rooted bovine teeth were instrumented with ProTaper rotary system and divided into four groups according to the final irrigation protocol (n = 10): (1) 17% EDTA (control); (2) 17% EDTA with 50-s ultrasonic agitation; (3) 17% EDTA with 50-s diode laser (2-W) agitation; and (4) 17% EDTA with 50-s Nd:YAG (1.5-W) laser agitation. After endodontic filling with gutta-percha F5 master cone and Sealer 26, the roots were sectioned at the cervical, middle, and apical root thirds to obtain 1.5-mm slices. Push-out tests were performed using a universal testing machine at a 1 mm/min crosshead speed. Data were analyzed using two-way ANOVA and Tukey's tests (α=0.05). Apical root thirds had significant higher retention values than cervical and middle thirds (p < 0.05). EDTA with 1064-nm Nd:YAG or 980-nm diode laser presented the highest retention values and was significantly different from EDTA with ultrasonic agitation and EDTA only (p < 0.05). Adhesive failures were predominant to EDTA only group. Mixed failures were predominant to all agitation groups. 1064-nm Nd:YAG and 980-nm diode laser EDTA agitation enhanced the retention of the epoxy-based sealer to the root canal walls compared with that due to EDTA only or EDTA with ultrasonic agitation.

This study evaluates the effect of two thermoplastic obturation systems (MicroSeal and Obtura II) on bond strength of different sealers to intraradicular dentin. Sixty root canals of human canines were prepared using ProTaper rotary files (crown-down technique) and irrigated with 2.5% sodium hypochlorite and 17% EDTA. The root canals were filled by MicroSeal, Obtura II, or lateral compaction techniques using AH Plus and Epiphany SE. 1.5 mm thick root slices were subjected to the push-out test. ANOVA and Tukey's test showed that the bond strength values (MPa) observed in the groups obturated with MicroSeal (2.96 ± 2.72) and Obtura II (2.68 ± 2.18) did not significantly differ from each other (p > 0.05) but were significantly higher than that observed in the group obturated with lateral condensation (2.01 ± 1.48; p < 0.05). There were no statistically significant differences in strength (p > 0.05) among the root canal thirds (cervical: 2.44 ± 2.03; middle: 2.50 ± 2.27; and apical: 2.70 ± 2.34). Adhesive failures were predominant (60%) in all groups. In conclusion, MicroSeal and Obtura II techniques, using AH plus sealer, increased the resistance to displacement of the filling material, when compared with lateral compaction. Moreover, when used with Epiphany SE, these obturation systems did not affect the bond strength of the material to root dentin.

Este relato descreve dois casos de remoção de fragmentos de instrumentos de terços apicais de canais radiculares utilizando um extrator personalizado e técnica da agulha modificada, respectivamente. No Caso 1, um extrator foi fabricado para remover fragmento de broca localizado no terço apical do canal radicular de um incisivo central superior. O uso deste extrator permitiu a remoção bem sucedida e conservadora do fragmento de instrumento. No Caso 2, uma agulha para anestesia modificada foi utilizada como um trépano para ganhar acesso ao redor de um fragmento de instrumento localizado na porção apical curva do canal mésio-vestibular de um molar inferior. Um segmento de fio de aço foi inserido no lúmen da agulha para envolver o fragmento metálico, permitindo sua remoção com rotação no sentido anti-horário e simultâneo movimento de retração. Métodos alternativos e criativos são úteis para a remoção intracanal de fragmentos metálicos durante o tratamento endodôntico.

This paper describes two cases of instrument fragment removal from the apical thirds of root canals using a customized extractor and a modified needle technique, respectively. In case 1, a customized extractor was manufactured to remove a bur fragment located in the apical root canal of a maxillary central incisor. The use of this extractor enabled successful and conservative removal of the instrument fragment. In case 2, a modified injection needle was used as a trepan to gain access around an instrument fragment located in the curved apical portion of the mesiobuccal canal of a mandibular molar. A segment of steel wire was inserted into the needle lumen to engage the metallic fragment, enabling its removal with counter-clockwise rotation and a simultaneous pull-out motion. Alternative and creative methods are useful for the management of intracanal metallic fragments during root canal treatment.

Este relato de caso descreve a obturação do canal radicular realizada sobre um grande fragmento da lima ProTaper S1 em um segundo molar inferior com pulpite irreversível. Uma lima ProTaper S1 fraturou durante a instrumentação do canal mésio-vestibular. Aproximadamente 10 mm de remanescente do fragmento da lima permaneceu nos terços apical e médio do canal. A obturação foi realizada sobre este fragmento usando guta-percha compactada termomecanicamente e cimento endodôntico. Achados radiográficos e ausência de sinais e sintomas clínicos após 3 anos de acompanhamento indicaram o sucesso do tratamento. Imagens de tomografia computadorizada de feixes cônicos revelaram a ausência de lesão periapical e detalhes do fragmento da lima intracanal relacionados à obturação do canal radicular e à morfologia do ápice. Neste caso, a presença de grande instrumento fraturado intracanal não teve impacto negativo no prognóstico endodôntico durante o período de acompanhamento.

This case report describes root canal filling performed over a large S1 ProTaper file fragment in a second mandibular molar with irreversible pulpitis. An S1 ProTaper file was fractured during the instrumentation of the mesiobuccal canal. Approximately 10 mm of file fragment remained in the apical and middle thirds of the canal. The obturation was performed over this fragment using thermomechanically compacted gutta-percha and sealer. Radiographic findings and the absence of clinical signs and symptoms at 3-year follow up indicated successful treatment. Cone-beam computed tomography images revealed absence of periapical lesion and details of intracanal file fragment related to root fillings and apex morphology. In this case, the presence of a large intracanal fractured instrument did not have a negative impact on the endodontic prognosis during the follow up evaluation period.

O objetivo deste estudo foi analisar as características clínico-radiográficas e microscópicas de uma série de casos de fibroma ossificante (FO). Para o estudo, todos os casos com diagnóstico de FO do arquivo do Laboratório de Patologia Bucal da Universidade de Ribeirão Preto, Ribeirão Preto, São Paulo, Brasil, foram estudados. Os dados clínicos foram coletados das fichas de encaminhamento das lesões ao Laboratório. As características radiográficas foram avaliadas em cada caso. Todos os casos foram revisados microscopicamente para confirmação do diagnóstico. Oito casos foram identificados, 5 em mulheres e 3 em homens. A idade média dos pacientes foi de 33,7 anos e a maioria das lesões (7 casos) ocorreu na mandíbula. Radiograficamente todas as lesões se apresentavam como imagens uniloculares e a maioria (5 casos) se mostravam como imagem mista. O tamanho médio do tumor foi de 3,1 cm e 3 casos causavam deslocamento dos dentes envolvidos. Microscopicamente, todos os casos apresentavam várias áreas mineralizadas semelhantes a osso, imersas em um tecido conjuntivo celularizado. Dos 8 casos, 5 foram submetidos a excisão cirúrgica da lesão e 1 paciente recusou tratamento. Nos outros 2 casos, essa informação não estava disponível. Conclui-se que o FOs ocorrem mais comumente na mandíbula de pacientes do gênero feminino durante a quarta década de vida e se apresentam frequentemente como uma imagem radiográfica mista. Diagnósticos diferenciais coerentes são importantes para guiar a conduta clínica mais adequada. A correlação entre as características clínicas, imaginológicas e histopatológicas é a chave para estabelecer o diagnóstico correto.

The aim of this study was to assess the clinical, radiographic and microscopic features of a case series of ossifying fibroma (OF) of the jaws. For the study, all cases with OF diagnosis from the files of the Oral Pathology Laboratory, University of Ribeirão Preto, Ribeirão Preto, SP, Brazil, were reviewed. Clinical data were obtained from the patient files and the radiographic features were evaluated in each case. All cases were reviewed microscopically to confirm the diagnosis. Eight cases were identified, 5 in females and 3 in males. The mean age of the patients was 33.7 years and most lesions (7 cases) occurred in the mandible. Radiographically, all lesions appeared as unilocular images and most of them (5 cases) were of mixed type. The mean size of the tumor was 3.1 cm and 3 cases caused displacement of the involved teeth. Microscopically, all cases showed several bone-like mineralized areas, immersed in the cellular connective tissue. From the 8 cases, 5 underwent surgical excision and 1 patient refused treatment. In the remaining 2 cases, this information was not available. In conclusion, OF occurs more commonly in women in the fourth decade of life, frequently as a mixed radiographic image in the mandible. Coherent differential diagnoses are important to guide the most adequate clinical approach. A correlation between clinical, imaginological and histopathological features is the key to establish the correct diagnosis.

OBJECTIVE: To assess the setting time (ST), flow (FL), radiopacity (RD), solubility (SB) and dimensional change following setting (DC) of different sealers (AH Plus®, Polifil, Apexit Plus®, Sealapex®, Endométhasone® and Endofill®) according to American National Standards Institute/American Dental Association (ANSI/ADA) Specification 57. MATERIAL AND METHODS: Five samples of each material were used for each test. For ST, cast rings were filled with sealers and tested with a Gilmore needle. For FL, the sealer was placed on a glass plate. After 180 s, another plate with 20 g and a load of 100 g were applied on the material, and the diameters of the discs formed were measured. In RD, circular molds were filled with the sealers, radiographed and analyzed using Digora software. For SB, circular molds were filled with the sealers, a nylon thread was placed inside the material and another glass plate was positioned on the set, pressed and stored at 37°C. Samples were weighed, placed in water, dried and reweighed. The water used for SB was analyzed by atomic absorption spectrometry. For DC, circular molds were filled with the sealers, covered by glass plates and stored at 37°C. Samples were measured and stored in water for 30 days. After this period, they were dryed and measured again. RESULTS: Regarding ST, AH Plus®, Apexit® and Endofil® sealers are in accordance with ANSI/ADA standards. Endométhasone's manufacturer did not mention the ST; Polifil is an experimental sealer and Sealapex® did not set. Considering RD, SB and DC, all sealers were in accordance with ANSI/ADA. The spectrometric analysis showed that a significant amount of K+ and Zn2+ ions was released from Apexit Plus® and Endofill®, respectively. CONCLUSION: Except for DC, all other physicochemical properties of the tested sealers conformed to ANSI/ADA requirements.

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.

O objetivo deste estudo foi avaliar a expressão imunoistoquímica de syndecan-1 (CD138) e Ki-67 em cistos radiculares (CR), cistos dentígeros (CD) e tumores odontogênicos queratocísticos (TOQ). Trinta e cinco CR, 22 CD e 17 TOQ foram utilizados no estudo e as reações imunoistoquímicas usando os anticorpos anti-syndecan-1 e anti-Ki-67 foram realizadas pelo método estreptavidina-biotina-peroxidase. Para análise estatística, o teste exato de Fisher e o coeficiente de correlação de Spearman foram utilizados. Entre as lesões estudadas, não foram observadas diferenças na expressão de syndecan-1, mas a expressão suprabasal de Ki-67 foi significativamente maior nos TOQ (p<0,0001), quando comparado aos CR e CD. No CR, havia correlação positiva entre a expressão (p=0,02) e intensidade (p=0,0001) de syndecan-1 e entre a intensidade de syndecan-1 e expressão de Ki-67 (p=0,01). No TOQ, a expressão de Ki-67 na camada suprabasal correlacionou positivamente com a expressão (p=0,01) e intensidade de expressão (p=0,01) de syndecan-1. A expressão de syndecan-1 não parece ser um fator determinante das características histopatológicas distintas e do comportamento biológico das lesões estudadas. Entretanto, correlação positiva entre syndecan-1 e um marcador de proliferação celular foi evidenciado em CR e TOQ.

The aim of this study was to assess the immunohistochemical expression of syndecan-1 (CD138) and Ki-67 in radicular cysts (RC), dentigerous cysts (DC) and keratocystic odontogenic tumors (KOT). Thirty-five RC, 22 DC and 17 KOT were used in the study and immunohistochemical reactions using anti-syndecan-1 and anti-Ki-67 antibodies were performed by the streptavidin-biotin-peroxidase method. Fisher's exact test and Spearman's correlation coefficient were used for statistical analysis of data. Among the studied lesions, no differences in the syndecan-1 expression were observed, but the suprabasal expression of Ki-67 was significantly higher in KOT (p<0.0001), when compared with RC and DC. In RC, there was positive correlation between the expression (p=0.02) and intensity (p=0.0001) of syndecan-1 and between the intensity of syndecan-1 and Ki-67 expression (p=0.01). In the KOT, Ki-67 expression in the suprabasal layer correlated positively with the expression (p=0.01) and intensity (p=0.01) of syndecan-1. The expression of syndecan-1 does not seem to be a determinant factor of the distinct histopathological features and biological behavior of the studied lesions. Nevertheless, positive correlation between syndecan-1 and a cell proliferation marker was observed in RC and KOT.

Este estudo avaliou o efeito de protocolos de clareamento com peróxido de hidrogênio 38% (PH) e tempos pós-clareamento na resistência ao cisalhamento de uma resina composta á dentina. Cem fragmentos de dentina intracoronária foram incluídos e distribuídos aleatoriamente em 2 grupos experimentais de acordo com o protocolo de clareamento: PH (2 aplicações de 10 min cada) e HP ativado por LED laser (2 aplicações de 10 min cada/45 s de ativação pela luz). Os grupos foram subdivididos de acordo com o tempo pós-clareamento (n=10): 1 dia, 3 dias, 7 dias, 10 dias e 14 dias. O grupo controle não foi clareado e apenas restaurado (n=10). Os espécimes foram restaurados com sistema adesivo Single Bond/resina Filtek Z250 usando matriz de teflon. Após 24 h, foram submetidos ao teste de cisalhamento. Os dados foram analisados por ANOVA e teste de Tukey (α=0,05). O grupo não clareado (0,283 ± 0,134) apresentou a maior resistência de união e foi estatisticamente semelhante (p>0,05) ao PH- 10 dias (0,278 ± 0,064), PH + LED laser/10 dias (0,280 ± 0,078), PH/14 dias (0,281 ± 0,104), PH + LED laser/14 dias (0,277 ± 0,093). Resistência de união inferior foram verificadas para PH/1 dia (0,082 ± 0,012), PH/3 dias (0,079 ± 0,013), PH + LED laser/1 dia (0,073 ± 0,018) e PH + LED laser/3 dias (0,080 ± 0,015), que foram estatisticamente semelhantes entre si (p>0,05). HP/7 dias (0,184 ± 0,154) e PH + LED laser/7 dias (0,169 ± 0,102) apresentaram valores intermediários (p<0,05). O procedimento restaurador da dentina intracoronária clareada com peróxido de hidrogênio 38%, com ou sem o uso de fonte de luz, deve ser realizado pelo menos após 10 dias do tratamento clareador.

This study assessed the effect of bleaching protocols with 38% hydrogen peroxide (HP) and post-bleaching times on shear bond strength of a composite resin to dentin. One-hundred slabs of intracoronary dentin were included and randomly assigned into 2 groups according to the bleaching protocol: HP (2 applications of 10 min each) and HP activated by LED laser (2 applications of 10 min each/45 s of light activation). Groups were subdivided according to the post-bleaching time (n=10): 1 day, 3 days, 7 days, 10 days and 14 days. The control group was unbleached and restored (n=10). The specimens were restored with Single Bond adhesive system/Filtek Z250 resin using a polytetrafluorethylene matrix and were submitted to the shear bond strength testa after 24 h,. Data were analyzed by ANOVA and Tukey's test (α=0.05). Unbleached group (0.283 ± 0.134) had the highest bond strength and was statistically similar (p>0.05) to HP/10 days (0.278 ± 0.064), HP + LED laser/10 days (0.280 ± 0.078), HP/14 days (0.281 ± 0.104), HP + LED laser/14 days (0.277 ± 0.093). Lower bond strength were verified in HP/1 day (0.082 ± 0.012), HP/3 days (0.079 ± 0.013), HP + LED laser/1 day (0.073 ± 0.018) and HP + LED laser/3 days (0.080 ± 0.015), which were statistically similar (p>0.05). HP/7 days (0.184 ± 0.154) and HP + LED laser/7 days (0.169 ± 0.102) had intermediate values (p<0.05). The restorative procedure of intracoronary dentin bleached with 38% HP with or without the use of light source should be performed after at least 10 days after the bleaching treatment.

Este estudo avaliou o efeito do laser de diodo 980 nm na microinfiltração apical e na morfologia intrarradicular da dentina. Raízes de 110 incisivos inferiores foram utilizadas no estudo: 92 para o teste de microinfiltração e 18 para microscopia eletrônica de varredura (MEV). As raízes foram divididas em 3 grupos de acordo com a solução irrigante (água, NaOCl e NaOCl/EDTA) e subdivididas em 3 de acordo com a irradiação laser (sem irradiação, irradiados com 1,5 W e irradiados com 3,0 W). Duas amostras de cada subgrupo foram preparadas para MEV. As raízes restantes foram preenchidas com AH Plus e guta percha. A infiltração apical foi avaliada nas raízes por meio da penetração do corante e os dados foram analisados por ANOVA e teste de Tukey-Krammer (α=0,05). Os resultados da MEV mostraram intensificação das mudanças quando se aumentou a potência do laser e variações de acordo com a solução irrigadora. Camada de smear modificada foi observada em espécimes tratados com água e irradiados com laser. Raízes irrigadas com NaOCl/EDTA tiveram níveis menores de infiltração (0,17 ± 0,18 mm) estatisticamente diferente (p<0,05) das raízes irrigadas com água (0,34 ± 0,30 mm), mas semelhante (p>0,05) aos irrigados com NaOCl (0,28 ± 0,29 mm). As raízes não irradiadas tiveram níveis menores de infiltração (0,10 ± 0,14 mm), diferente (p<0,05) de 1,5 W (0,32 ± 0,22 mm) e 3.0 W (0,37 ± 0,32 mm). O laser de diodo 980 nm alterou a morfologia da dentina e aumentou a infiltração marginal apical.

This study evaluated the effect of 980-nm diode laser on apical microleakage and intraradicular dentin morphology. Roots of 110 mandibular incisors were used in the study: 92 for microleakage test and 18 for scanning electron microscopy (SEM). Roots were randomly assigned to 3 groups according to the irrigating solution (water, NaOCl and NaOCl/EDTA) and were divided into 3 subgroups according to the laser irradiation protocol (without irradiation, irradiated at 1.5 W and irradiated at 3.0 W). Two specimens of each subgroup were prepared for SEM. The remaining roots were filled with AH Plus and gutta-percha. Apical leakage was assessed by ink penetration and data were analyzed statistically by ANOVA and Tukey-Krammer test (α=0.05). SEM analysis showed intensification of changes with increase of laser power as well as variations according to the irrigating solution. Modified smear layer was observed in specimens treated with water and irradiated with laser. Roots irrigated with NaOCl/EDTA had lower levels of infiltration (0.17 ± 0.18 mm) differing significantly (p<0.05) from those of roots irrigated with water (0.34 ± 0.30 mm), but similar (p>0.05) to those irrigated with NaOCl (0.28 ± 0.29 mm). Non-irradiated roots had lower levels of infiltration (0.10 ± 0.14 mm), differing (p<0.05) from those irradiated at 1.5 W (0.32 ± 0.22 mm) and 3.0 W (0.37 ± 0.32 mm). The 980 nm diode laser modified dentin morphology and increased apical microleakage.

Este estudo avaliou a resistência à fratura de dentes submetidos ao clareamento interno restaurados com diferentes procedimentos. Quarenta incisivos superiores foram tratados endodonticamente e divididos em 4 grupos (n = 10): G1- restaurados com resina composta (RC), G2- clareados com peróxido de hidrogênio (PH) e restaurados com o RC, G3- restaurado com RC e pinos de fibra de vidro (RC + pinos) e G4- clareados e restaurados com RC + pinos. O PH foi aplicado na superfície vestibular e câmara pulpar 3 vezes por sessão, por 2 sessões com intervalo de 7 dias entre elas. Dez dentes hígidos adicionais foram submetidos a teste fratura (padrão ouro). A resistência à fratura (kN) foi determinada em máquina Instron. Os dados foram analisados por Análise de Variânica e teste de Tukey-Krammer (α= 0,05). Os dentes não tratados (padrão ouro) apresentaram a maior resistência à fratura (0,43 ± 0,16) (p <0,05). Os dentes restaurados com RC (G1) apresentaram a menor resistência à fratura (0,23 ± 0,11) (p <0,05). Os dentes clareados e restaurados com RC (G2) (0,26 ± 0,10), restaurado com RC + pinos (G3) (0,31 ± 0,17) e os clareados e restaurados com RC + pinos (G4) (0,33 ± 0,12) apresentaram valores intermediários, ora semelhantes ao do grupo com o maior valor, ora similares ao grupo de valores mais baixos. Pode-se concluir que os dentes submetidos ao clareamento interno podem ser restaurados com apenas resina composta.

This study evaluated the fracture resistance of teeth submitted to internal bleaching and restored with different procedures. Forty maxillary incisors were endodontically treated and assigned to 4 groups (n=10): G1- restored with composite resin (CR), G2- bleached with hydrogen peroxide (HP) and restored with CR, G3- restored with CR and fiberglass posts (CR + posts) and G4- bleached and restored with CR + posts. HP was applied in the buccal surface and pulp chamber 3 times at each one of 2 sessions with an interval of 7 days between them. Additional 10 sound incisors were subjected to fracture strength test (gold standard). The fracture strength (kN) was determined in an Instron machine. Data were analyzed by ANOVA and Tukey-Kramer test (α=0.05). The untreated teeth (gold standard) showed the highest (p<0.05) fracture strength (0.43 ± 0.16). Teeth restored with CR (G1) without internal bleaching had the lowest (p<0.05) fracture strength (0.23 ± 0.11). Teeth bleached and restored with CR (G2) (0.26 ± 0.10), restored with CR + posts ithout internal bleaching (G3) (0.31 ± 0.17) and, bleached and restored with CR + posts (G4) (0.33 ± 0.12) had intermediate values, sometimes similar to the group with the highest value, sometimes similar to the group with the lowest value. In conclusion, as far as the fracture strength is concerned, teeth subjected to internal bleaching can be restored with composite resin alone, as the use of posts in these teeth did not increase their resistance.

O objetivo do presente estudo foi avaliar a remoção de smear layer por meio da microscopia eletrônica de varredura (MEV) e quantificar a liberação de íons cálcio resultante da irrigação com as soluções quelantes estudadas, por meio da espectrofotometria de absorção atômica. Dezesseis caninos extraídos foram instrumentados com a técnica step-back e divididos em 3 grupos de acordo com a solução irrigadora utilizada: G1: 1 mL de EDTAC a 17% entre cada lima; G2: CDTA a 17%; e G3: EGTA a 17%. As soluções foram coletadas após o uso. Os dentes foram secionados longitudinalmente e as raízes examinadas por MEV para verificação de smear layer nos terços por meio de escores (variando de 1 a 4), e avaliadas por três examinadores calibrados "cegos". Para quantificar a liberação de íons cálcio, as soluções coletadas foram avaliadas por espectrofotometria de absorção atômica. Com relação ao smear layer, o teste de Friedman evidenciou diferença estatisticamente significante (p<0,01) comparando-se o EGTA 17% ao EDTAC 17% e ao CDTA 17%, sendo que os canais irrigados com estas duas soluções apresentaram menor quantidade de smear layer que aqueles irrigados com EGTA. As soluções de EDTAC 17% (70,5±14,2 µg/mL Ca) e CDTA 17% (60,6±20,67 µg/mL Ca) apresentaram maiores quantidades de íons cálcio (p<0,01) quando comparadas ao EGTA 17% (22,8±7,54 µg/mL Ca). Desta forma, pode-se concluir que a associação destas metodologias pode contribuir para o entendimento da ação das soluções quelantes no interior dos canais radiculares.

The purpose of this study was to evaluate, by scanning electron microscopy (SEM), smear layer removal and quantify, by atomic absorption spectrophotometry, the amount of calcium ion present in the chelating solutions after their use. Sixteen extracted canines were instrumented using the step-back technique and were assigned to 3 groups according to the irrigating solution used: G1: 1 mL 17% EDTAC between each file; G2: 1 mL 17% CDTA; G3: 1 mL 17% EGTA. The solutions were collected after use. The teeth were cleaved longitudinally, evaluated under SEM and assessed for smear layer by blinded examiners and scored from 1 to 4. In order to quantify calcium ion release, the collected solutions were examined by atomic absorption spectrophotometry. Freidman's test was used for statistical analysis of SEM values and showed that canals irrigated with 17% EDTAC and 17% CDTA had significantly less smear layer throughout the canals than 17% EGTA (p<0.01). For analysis of the collected solutions, Tukey's test was used and showed that EDTAC and CDTA had a greater amount of calcium ions (22.8±7.54 and 60.6±20.67 µg/mL, respectively) compared to EGTA (70.5±14.2 µg/mL) (p<0.01). The association both methodologies may contribute to the understanding of how these solutions act in the root canal.