Resumo Os objetivos deste estudo foram avaliar as propriedades físicas e químicas, citototoxidade e penetração tubular de uma nova medicação à base de silicato de cálcio. Para o teste de pH, e liberação de íons cálcio (1, 24, 72 e 168 h) foi usado medidor de pH e espectofotômetro colorimétrico, respectivamente. Avaliação da radiopacidade, seguiu a ISO 6876:2012). A citotoxicidade foi avaliada pela porcentagem de células viáveis usando o ensaio MTT. Imagens ilustrativas de penetração tubular foram obtidas usando microscopia confocal de varredura a laser (CLSM). Os dados de pH e liberação de cálcio foram analisados através do teste de Análise de Variância de duas vias e teste de Tukey. A radiopacidade foi avaliada usando o teste T de Student. Para a citotoxicidade foi empregada a Análise de Variância de uma via e teste de Tukey. Ambos os materiais apresentaram pH alcalino em todos os tempos experimentais. Os valores de pH da pasta de hidróxido de cálcio foram superiores à pasta biocerâmica em 1, 24 e 72 h (p<0,05). A liberação de cálcio da pasta biocerâmica foi inferior à pasta de hidróxido de cálcio apenas em 24 h (p<0,05). Bio-C Temp foi mais radiopaco que o Ultracal XS (p<0,05). A pasta biocerâmica apresentou efeito citotóxico dependente da dose e do tempo de exposição. Imagens de CLSM mostraram ausência de penetração intratubular para ambas as pastas. A nova medicação à base de silicato de cálcio apresentou pH alcalino, alta liberação de cálcio e boa radiopacidade. Bio C Temp apresentou um efeito citotóxico dependente da dose e do tempo de exposição e ausência de penetração tubular.

Abstract The aims of this study were to evaluate the physical and chemical properties, cytotoxicity and dentinal tubule penetration of a new calcium silicate-based root canal dressing. For pH and calcium ion release evaluation (1, 24, 72 and 168 h) were used a pH meter and colorimetric spectrophotometer, respectively. Radiopacity evaluation followed the ISO 6876:2012. Cytotoxicity was evaluated by the percentage of cell viability using MTT assay. Illustrative images of dentinal tubule penetration were obtained using confocal laser scanning microscopy (CLSM). Data from pH and calcium ion release were statistically analyzed by two-way analysis of variance and Tukey test. Radiopacity was analyzed using the Student t-test. The statistical tests for cytotoxicity results were the one-way analysis of variance and Tukey test. Both materials showed alkaline pH in all experimental times. The pH values for calcium hydroxide paste were higher than bioceramic paste at 1, 24, and 72 h (p<0.05). The calcium ion release of bioceramic was lower than the calcium hydroxide paste only at 24 h (p<0.05). The bioceramic was more radiopaque than the calcium hydroxide paste (p<0.05). Bioceramic paste presented a dose and time-dependent cytotoxic effect after MTT assay. CLSM images showed absence of tubule penetration for both pastes. The new calcium silicate-based canal dressing presented alkaline pH, high calcium release, and acceptable radiopacity. Bio C Temp showed a dose and time-dependent cytotoxic and absence of dentinal tubule penetration.

Resumo O objetivo deste estudo foi verificar se as modificações feitas com o adesivo etil cianoacrilato, ECA (Super Bonder ®, Loctite, Itapevi, SP, Brasil) sobre as resinas acrílicas para reembasamento, poderiam inibir ou reduzir a formação de biofilmes de C.albicans sobre sua superfície quando comparado com um selante de superfície comercial (BisCover®, Bisco, Schaumburg, EUA). Amostras de resina acrílica para reembasamento foram fabricadas e divididas aleatoriamente em 6 grupos (n=8): CG (grupo controle), sem tratamento superficial; ECA1, revestimento de ECA na superfície antes da esterilização; ECA2, revestimento de ECA após esterilização; ECA3, ECA incorporado no volume da resina; DPE1, revestimento de BisCover® antes da esterilização; DPE2, revestimento de BisCover® após esterilização. Os espécimes foram inoculados com C. albicans SC5314 (1x107 células/mL) e incubados durante 24 h. Seguidamente, o biofilme foi corado com LIVE/DEAD® BaclightTM L7007 Kit e analisado no microscópio confocal de varredura a laser. As imagens foram avaliadas pelo software bioImageL® v.2.0, no qual foram calculados o biovolume total (μm3), as células viáveis (%) e a área coberta (%). Os dados foram analisados estatisticamente pelos testes de Kruskal-Wallis e Dunn (p<0,05). Os resultados mostraram que os grupos revestidos com ECA apresentaram os melhores resultados, reduzindo a formação do biofilme de C. albicans. As imagens adquiridas revelaram que esses grupos (ECA1 e ECA2) apresentaram um número reduzido de células, principalmente na forma de levedura (menos patogênico), enquanto os outros grupos apresentaram um maior número de células, principalmente na forma de hifas (mais patogênicas). Com base nessas descobertas, encontra-se um efeito benéfico na aplicação do adesivo ECA sobre as superfícies das resinas acrílicas para reembasamento, sugerindo assim uma nova alternativa de prevenir a formação de biofilme fúngico em próteses dentárias.

Abstract The aim of this study was to verify whether modifications made in a hard chairside reline resin by an ethyl-cyanoacrylate adhesive, ECA (Super Bonder®, Loctite, Itapevi, SP, Brazil) would be able to inhibit or reduce Candida albicans biofilm formation on its surface, comparing to a commercial surface sealant (BisCover®, Bisco, Schaumburg, USA). Reline resin specimens were fabricated and randomly divided into 6 groups (n=8): CG (control group), no surface treatment; ECA1, ECA coating on the surface before sterilization; ECA2, ECA coating after sterilization; ECA3, ECA incorporated in the resin bulk; DPE1, BisCover® coating before sterilization; DPE2, BisCover® coating after sterilization. Specimens were inoculated with C. albicans SC5314 (1x107 cells/mL) and incubated for 24 h. Then, the biofilm were stained with LIVE/DEAD® BaclightTM L7007 Kit and analyzed by Confocal Laser Scanning Microscopy. The images were evaluated by bioImageL® v.2.0 software and total biovolume (µm3), viable cells (%), and covered area (%) were calculated. Data were statistically analyzed by Kruskal-Wallis and Dunn tests (p<0.05). Results showed that ECA-coated groups presented better results, reducing C. albicans biofilm formation. Acquired images revealed that these groups (ECA1 and ECA2) presented a reduced number of cells, mostly in yeast form (less pathogenic), while the other groups presented higher number of cells, mostly in hyphae form (more pathogenic). Based on these findings, a beneficial effect of Super Bonder® coating reline resins surface could be demonstrated, suggesting a promising way to prevent fungal biofilm formation on dentures.

Resumo O objetivo dente estudo foi quantificar o material obturador residual após remoção da obturação, repreparo do canal com instrumentos de rotação contínua e reciprocantes e após irrigação ultrassônica passiva (IUP). Vinte molares superiores foram preparados usando instrumentos ProTaper sequencialmente até F1. Os dentes foram obturados com AH Plus e cones de guta percha ProTaper utilizando a técnica de cone único. Em seguida, os espécimes foram submetidos à microtomografia computadorizada (Micro-CT #1). Então, o material obturador foi removido utilizando instrumentos ProTaper Retratamento e novo escaneamento foi realizado (Micro-CT #2). Os espécimes foram divididos em dois grupos de acordo com o instrumento usado para o repreparo: de rotação contínua (ProTaper) ou reciprocante (WaveOne) (Micro-CT #3). Finalmente, IUP foi realizada e nova micro-CT foi conduzida (Micro-CT #4). As análises intra-grupo e inter-grupos foram realizadas utilizando os testes de Friedman e de Dunn e o teste de Kruskal-Wallis e Dunn, respectivamente. O canal palatino apresentou o maior volume de material obturador remanescente em todos os estágios do tratamento endodôntico (p<0,05). A maior redução do volume da obturação foi obtida após usar os instrumentos ProTaper Retratamento (p<0,05). A quantidade de material obturador remanescente após utilizar instrumentos ProTaper Retratamento foi similar àquela obtida após repreparo com instrumentos de rotação contínua e reciprocantes e após a IUP (p>0,05). Instrumentos de rotação contínua e reciprocantes proporcionaram similar remoção de material obturador (p>0,05). A maior redução do volume de material obturador foi obtida após utilizar os instrumentos ProTaper Retratamento. Instrumentos de rotação contínua e reciprocantes, assim como a IUP, não reduzíram o volume de material obturador remanescente.

The aim of this study was to quantify the residual filling material after filling removal, re-preparation with rotary or reciprocating files and passive ultrasonic irrigation (PUI). Twenty maxillary molars were prepared using ProTaper instruments up to F1. The teeth were filled with AH Plus and ProTaper gutta-percha points using the single-cone technique. Thereafter, the specimens were scanned using a micro-computed tomography system (Micro-CT #1). Then, the root canal filling was removed using ProTaper Retreatment files, and a new scan was performed (Micro-CT #2). The specimens were divided into two groups according to the instrument used for re-preparation: ProTaper rotary or WaveOne reciprocating files (Micro-CT #3). Finally, PUI was performed, and a new micro-CT scan was performed (Micro-CT #4). Intragroup and intergroup analyses were performed using Friedman and Dunn's post hoc test and the Kruskal-Wallis and Dunn post hoc tests, respectively. Palatal canal presented the highest volume of residual filling material in all stages of endodontic retreatment (p<0.05). The main reduction of filling volume was achieved after using ProTaper Retreament (p<0.05). The amount of remaining filling material after using ProTaper Retreatment was similar to that achieved with rotary and reciprocating files and after PUI (p>0.05). Rotary and reciprocating files achieved similar removal of the root canal filling (p>0.05). The greatest reduction in filling material was achieved after using ProTaper Retreatment files. Rotary and reciprocating instruments and PUI did not improve the removal of root canal filling materials.

Objetivo Avaliar o efeito da dentina sobre o pH e a atividade antimicrobiana de formulações com hidróxido de cálcio. Material e método O pH e a atividade antimicrobiana das formulações (G1- polietilenoglicol, G2- glicerina e paramonoclorofenol canforado ou G3- clorexidina) foram analisados nas formulações puras (G1A, G2A e G3A) ou acrescidas de dentina em pó (G1B, G2B e G3B). Tubos de polietileno foram preenchidos com uma das formulações e imersos em água destilada. O pH foi analisado após 24 horas, 7, 14 e 21 dias. A atividade antimicrobiana foi avaliada sobre Enterococcus faecalis (ATCC 29212), através do teste de difusão em ágar. Os resultados foram submetidos aos testes de ANOVA e Tukey (p=0,05). Resultado A dentina não exerceu efeito sobre o pH das formulações, exceto ocasionando a redução em G1, no período de 24 horas (p<0,05). Nas demais formulações, não houve interferência da dentina sobre o pH (p>0,05). Quando comparados entre os grupos, em 24 horas e 7 dias, G1A e G1B apresentaram menor pH (p<0,05). Em 14 dias, G2A, G2B, G3A e G3B demonstraram similar pH (p>0,05), assim como entre G3B e G1A (p>0,05). Em 21 dias, todas as formulações demonstram semelhante pH (p>0,05). Os resultados em ordem decrescente da atividade antimicrobiana foram G2A=G2B>G3A=G3B>G1A=G1B (p<0,05). Conclusão A dentina não interferiu no pH e na atividade antimicrobiana das diferentes formulações com hidróxido de cálcio, exceto na associação com o polietilenoglicol, em que ocasionou a redução do pH apenas no período de 24 horas. A formulação com paramonoclorofenol canforado apresentou maior atividade antimicrobiana, seguida da clorexidina e do polietilenoglicol.

Objective To evaluate the dentin effect on pH and antimicrobial activity of the calcium hydroxide chemical formulations. Material and method pH and antimicrobial activity of calcium hydroxide formulations were evaluated (G1-polyethyleneglycol, G2-glycerin and camphorated paramonochlorophenol and G3-chlorhexidine). The formulations were evaluated alone (G1A, G2A e G3A) or with dentin powder (G1B, G2B and G3B). Polyethylene tubes were filled with the formulation and immersed in distilled water. After 24 hours, 7, 14 and 21 days, pH was evaluated. The antimicrobial activity was evaluated against Enterococcus faecalis by agar diffusion test. All data were submitted to ANOVA and Tukey tests (p=0.05). Result None effect was observed on pH and antimicrobial activity by dentin on different chemical formulations, except the reduction occurred in G1 at 24 hours (p <0.05). When compared between the groups at 24 hours and 7 days, G1A and G1B had a lower pH (p <0.05). At 14 days, G2A, G2B, G3A and G3B showed similar pH (p <0.05) and between G3B and G1A (p> 0.05). At 21 days, all formulations were similar (p> 0.05). Regarding antimicrobial activity G2B G2A => = G3A G3B> = G1A G1B (p <0.05). Conclusion The dentin did not affect the pH and antimicrobial activity of different formulations containing calcium hydroxide, except in association with polyethylene glycol, which caused the reduction of pH, within 24 hours. The formulation with paramonochlorophenol camphor showed higher antimicrobial activity, followed by chlorhexidine and polyethylene glycol.

This study evaluated the association of level of anxiety in children with and without sleep bruxism (SB). The study was performed with 84 six- to eigth-years-old children, divided into two groups: with bruxism (BG) and without bruxism (CG). Following the criteria purposed by American Academy of Sleep Medicine (AASM) to determine SB, the presence of tooth wear has been verified through clinical examinations, and the parents have answered a questionnaire about their children’s behavior and habits. Additionally, the State-Trait Anxiety Inventory for Children (STAIC) was applied to parents of the selected patients. Data analysis revealed a statistical significant difference between the groups (Student’s t-test, p= 0.0136). Based on the results, anxiety assessment revealed that children with bruxism have reached higher levels in the STAIC scale than the non-bruxism group. Therefore, it indicates a direct relationship between the presence of anxiety disorder and the onset of bruxism in children.

OBJECTIVE: The purpose of this study was to assess the push-out bond strength of glass fiber posts to root dentin after cementation with glass ionomer (GICs) and resinmodified glass ionomer cements (RMGICs). MATERIAL AND METHODS: Fifty human maxillary canines were transversally sectioned at 15 mm from the apex. Canals were prepared with a step back technique until the application of a #55 K-file and filled. Post spaces were prepared and specimens were divided into five groups according to the cement used for post cementation: Luting & Lining Cement; Fuji II LC Improved; RelyX Luting; Ketac Cem; and Ionoseal. After cementation of the glass fiber posts, all roots were stored at 100% humidity until testing. For push-out test, 1-mm thick slices were produced. The push-out test was performed in a universal testing machine at a crosshead speed of 0.5 mm/minute and the values (MPa) were analyzed by Kolmogorov-Smirnov and Levene's tests and by two-way ANOVA and Tukey's post hoc test at a significance level of 5%. RESULTS: Fiber posts cemented using Luting & Lining Cement, Fuji II LC Improved, and Ketac Cem presented the highest bond strength to root dentin, followed by RelyX Luting. Ionoseal presented the lowest bond strength values (P>0.05). The post level did not influence the bond strength of fiber posts to root dentin (P=0.148). The major cause of failure was cohesive at the cement for all GICs and RMGICs. CONCLUSIONS: Except for Ionoseal, all cements provided satisfactory bond strength values.

AIM: To investigate the amount of connective tissue migrated into the extraction socket using EPTFE and latex membranes. METHODS: Seventeen rats were selected and randomly divided into 3 groups: e-PTFE membrane (n = 6), Latex membrane (n = 6) and Control (no membrane, n=5). After extraction of the maxillary right incisor, the animals of the test groups were subjected to alveolar guided bone regeneration (GBR) surgery and received an expanded polytetrafluoroethylene (e-PTFE) and a latex membrane, respectively. Thirty days after surgery, the animals were killed and histometric analysis was done to evaluate the migration of connective tissue. Data were analyzed statistically by one-way ANOVA and multiple-comparison Tukey's test at 5% significance level. RESULTS: There was statistically significant difference between groups e-PTFE and Latex (p=0.001), and between groups e-PTFE and Control (p=0.012), but no significant difference was found between groups Latex and Control (p=0.416). CONCLUSIONS: The e-PTFE membrane showed better results and appeared more adequate for GBR therapy, forming a barrier to prevent the migration of connective tissue into the extraction socket. The latex membrane, on the other hand, did not show benefits over the control group.

OBJECTIVE: This study has two aims: 1) to evaluate the apical transportation of the Wizard CD Plus and ProTaper Universal after preparation of simulated root canals; 2) to compare, with Adobe Photoshop, the ability of a new software (Regeemy) in superposing and subtracting images. MATERIAL AND METHODS: Twenty five simulated root canals in acrylic-resin blocks (with 20º curvature) underwent cone beam computed tomography before and after preparation with the rotary systems (70 kVp, 4 mA, 10 s and with the 8×8 cm FoV selection). Canals were prepared up to F2 (ProTaper) and 24.04 (Wizard CD Plus) instruments and the working length was established to 15 mm. The tomographic images were imported into iCAT Vision software and CorelDraw for standardization. The superposition of pre- and post-instrumentation images from both systems was performed using Regeemy and Adobe Photoshop. The apical transportation was measured in millimetres using Image J. Five acrylic resin blocks were used to validate the superposition achieved by the software. Student's t-test for independent samples was used to evaluate the apical transportation achieved by the rotary systems using each software individually. Student's t-test for paired samples was used to compare the ability of each software in superposing and subtracting images from one rotary system per time. RESULTS: The values obtained with Regeemy and Adobe Photoshop were similar to rotary systems (P>0.05). ProTaper Universal and Wizard CD Plus promoted similar apical transportation regardless of the software used for image's superposition and subtraction (P>0.05). CONCLUSION: Wizard CD Plus and ProTaper Universal promoted little apical transportation. Regeemy consists in a feasible software to superpose and subtract images and appears to be an alternative to Adobe Photoshop.

OBJETIVO: determinar as características mecânicas de alças em gota e em gota com helicoide, quando da incorporação de variações na liga metálica (aço inoxidável e beta-titânio), na intensidade de dobras de pré-ativação (0º e 40º) e na secção transversal do fio utilizado para a construção dessas alças (0,017" x 0,025" e 0,019" x 0,025"). MÉTODOS: foram submetidas ao ensaio mecânico 80 alças para fechamento de espaços, sendo quantificadas as magnitudes de força horizontal, proporção momento/força e relação carga/deflexão produzidas pelos corpos de prova. As alças foram submetidas a uma ativação total de 5,0mm, sendo registrados os valores a cada 1,0mm de ativação. No tratamento estatístico dos dados obtidos, foi realizada a análise de variância, sendo essa complementada pelo teste de comparações múltiplas de Tukey, considerando o nível de significância de 5%. RESULTADOS: de maneira geral, as alças em gota com helicoide produziram menores magnitudes de força horizontal e relação carga/deflexão e maiores valores de proporção momento/força do que as alças em gota. Dentre todas as variáveis analisadas, aquela que apresentou uma maior influência na força horizontal e na relação carga/deflexão produzidas pelas alças foi a liga metálica. Já a proporção momento/força mostrou ser influenciada em maior grau pela pré-ativação das alças de fechamento de espaços.

OBJECTIVE: To determine the mechanical characteristics of teardrop loop with and without helix fabricated using different metal alloy compositions (stainless steel and beta-titanium), submitted to different intensities of bends preactivation (0º and 40º), and with different cross-sectional dimension of the wire used to build these loops (0.017 x 0.025-in and 0.019 x 0.025-in). METHODS: Eighty loops used to close spaces were submitted to mechanical tests. The magnitudes of horizontal force, the moment/force ratio, and the load/deflection ratio produced by the specimens were quantified. Loops were submitted to a total activation of 5.0 mm and the values were registered for each 1.0 mm of activation. For statistic data analysis, a analysis of variance was performed and a Tukey's Multiple Comparison test was used as supplement, considering a 5% level of significance. RESULTS: In general, teardrop loops with helix produced lower magnitudes of horizontal force and load/deflection ratio, and higher moment/force ratio than teardrop loops without helix. Among all analyzed variables, metal alloy composition presented greater influence in the horizontal force and in the load/deflection ratio. The moment/force ratio showed to be more influenced by the preactivation of loops for space closure.

AIM: This study compared the resistance to fracture of endodontically treated teeth restored with different intraradicular posts with different lengths and full coverage metallic crowns. METHODS: Sixty extracted human canine teeth were randomly divided into 6 groups. Groups CP5, CP75 and CP10 were restored using custom cast post and core (CP) and groups PF5, PF75 and PF10 were restored with provisional pre-fabricated tin post (PF) and composite resin core at 5 mm, 7.5 mm and 10 mm of intraradicular length, respectively. The specimens were submitted to dynamic cyclic loading and those that resisted to this load were submitted to load compression using a universal testing machine. Compressive load was applied at a 45-degree angle to the long axis of the tooth until failure. RESULTS: Kruskal-Wallis one-way analysis of variance by ranks showed statistically significant differences among the groups (p<0.0001). However, when the means were compared using the Tukey's test, significant differences were noted between groups CP5 and CP10 and between groups CP10 and PF5. All groups presented root fractures and post displacements during mechanical cycling. All teeth in groups CP5 and PF5 failed the dynamic cycling test. CONCLUSIONS: This study showed that increasing intraradicular post length also increases resistance to fracture of endodontically treated teeth. On the other hand, most endodontically treated teeth restored with pre-fabricated tin posts (provisional posts) failed in the dynamic cycling test.

OBJECTIVE: This study investigated the role of periodontal disease in the development of stroke or cerebral infarction in patients by evaluating the clinical periodontal conditions and the subgingival levels of periodontopathogens. MATERIAL AND METHODS: Twenty patients with ischemic (I-CVA) or hemorrhagic (H-CVA) cerebrovascular episodes (test group) and 60 systemically healthy patients (control group) were evaluated for: probing depth, clinical attachment level, bleeding on probing and plaque index. Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans were both identified and quantified in subgingival plaque samples by conventional and real-time PCR, respectively. RESULTS: The test group showed a significant increase in each of the following parameters: pocket depth, clinical attachment loss, bleeding on probing, plaque index and number of missing teeth when compared to control values (p<0.05, unpaired t-test). Likewise, the test group had increased numbers of sites that were contaminated with P. gingivalis (60%x10%; p<0.001; chi-squared test) and displayed greater prevalence of periodontal disease, with an odds ratio of 48.06 (95% CI: 5.96-387.72; p<0.001). Notably, a positive correlation between probing depth and the levels of P. gingivalis in ischemic stroke was found (r=0.60; p=0.03; Spearman's rank correlation coefficient test). A. actinomycetemcomitans DNA was not detected in any of the groups by conventional or real-time PCR. CONCLUSIONS: Stroke patients had deeper pockets, more severe attachment loss, increased bleeding on probing, increased plaque indexes, and in their pockets harbored increased levels of P. gingivalis. These findings suggest that periodontal disease is a risk factor for the development of cerebral hemorrhage or infarction. Early treatment of periodontitis may counteract the development of cerebrovascular episodes.

Dental impression is an important step in the preparation of prostheses since it provides the reproduction of anatomic and surface details of teeth and adjacent structures. The objective of this study was to evaluate the linear dimensional alterations in gypsum dies obtained with different elastomeric materials, using a resin coping impression technique with individual shells. A master cast made of stainless steel with fixed prosthesis characteristics with two prepared abutment teeth was used to obtain the impressions. References points (A, B, C, D, E and F) were recorded on the occlusal and buccal surfaces of abutments to register the distances. The impressions were obtained using the following materials: polyether, mercaptan-polysulfide, addition silicone, and condensation silicone. The transfer impressions were made with custom trays and an irreversible hydrocolloid material and were poured with type IV gypsum. The distances between identified points in gypsum dies were measured using an optical microscope and the results were statistically analyzed by ANOVA (p < 0.05) and Tukey's test. The mean of the distances were registered as follows: addition silicone (AB = 13.6 µm, CD=15.0 µm, EF = 14.6 µm, GH=15.2 µm), mercaptan-polysulfide (AB = 36.0 µm, CD = 36.0 µm, EF = 39.6 µm, GH = 40.6 µm), polyether (AB = 35.2 µm, CD = 35.6 µm, EF = 39.4 µm, GH = 41.4 µm) and condensation silicone (AB = 69.2 µm, CD = 71.0 µm, EF = 80.6 µm, GH = 81.2 µm). All of the measurements found in gypsum dies were compared to those of a master cast. The results demonstrated that the addition silicone provides the best stability of the compounds tested, followed by polyether, polysulfide and condensation silicone. No statistical differences were obtained between polyether and mercaptan-polysulfide materials.

O objetivo neste estudo foi avaliar a resistência à fratura de dentes tratados endodonticamente restaurados com diferentes pinos e diferentes alturas de remanescente dentinário da coroa. Sessenta caninos recém-extraídos foram tratados endodonticamente, separados em 6 grupos (n=10) e restaurados com núcleo metálico fundido (CP0 e CP3), pino pré-fabricado e núcleo em resina composta (PF0 e PF3) ou resina composta (CR0 e CR3). Os grupos CP0, PF0 e CR0 não possuíam férula e os grupos CP3, PF3 e CR3 apresentaram 3 mm de remanescente coronário. Todos os dentes foram restaurados com coroas totais metálicas. A resistência à fratura foi medida em máquina universal de ensaios com o longo eixo do dente posicionado a 45 graus em relação ao carregamento axial, até que ocorresse fratura. A análise de variância 2 critérios (?=0,05) mostrou diferença estatisticamente significativa entre os grupos. Quando as médias das forças para fratura foram comparadas (CP0 = 820,0 N; CP3= 1179,12 N; PF0 = 561,05 N; PF3 = 906,79 N; CR0 = 297,84 N; e CR3 = 1135,15 N) não foram observadas diferenças significativas entre os 3 grupos com 3 mm de remanescente coronal. Os resultados mostraram que a presença de férula em coroas aumenta significantemente a resistência à fratura de dentes tratados endodonticamente.

The aim of this study was to investigate the fracture strength of endodontically treated teeth restored with different posts and variable ferrule heights. Sixty freshly extracted human canines were treated endodontically and randomly assigned to 6 groups (n=10), being restored with custom-made cast post-and-core (CP0 and CP3 groups), prefabricated post and composite resin core (PF0 and PF3 groups), and composite resin (CR0 and CR3 groups). The CP0, PF0 and CR0 groups presented no ferrule and the CP3, PF3 and CR3 presented 3 mm of coronal structure. All teeth were restored with full metal crowns. The fracture strength was measured in a universal testing machine at 45o to the long axis of the tooth until failure. Data were analyzed statistically by 2-way ANOVA and Tukey's test (?=0.05). When the mean fracture strength values were compared (CP0 group - 820.20 N, CP3 group - 1179.12 N; PF0 group - 561.05 N; PF3 group - 906.79 N; CR0 group - 297.84 N; and CR3 group - 1135.15 N) there was statistically significant among the groups (p<0.05), except for the three groups with 3 mm of coronal remaining, which were similar to each other. The results of this study showed that the ferrule in crowns promoted significantly higher fracture strength in the endodontically treated teeth.

Este estudo avaliou a resistência à fratura de raízes fragilizadas restauradas com pinos de fibra de vidro, núcleos de resina composta e coroas totais metálicas. Trinta caninos superiores foram aleatoriamente divididos em 3 grupos. Dentes sem enfraquecimento (grupo controle); grupo de raízes parcialmente enfraquecidas e amplamente enfraquecidas. O grupo controle foi restaurado com pinos de fibra de vidro e núcleo em resina composta. Os dentes dos grupos de raízes parcialmente e amplamente enfraquecidas foram internamente preparadas de maneira padronizada simulando enfraquecimento. Após isto, as raízes foram parcialmente preenchidas com resina composta e restauradas como no grupo controle. Os espécimes foram expostos a 250.000 ciclos em uma máquina de ciclagem mecânica. Todos os dentes intactos foram submetidos à carga estática (N) em uma máquina de ensaio universal a 45 graus ao longo eixo do dente até a sua falha. Os resultados foram analisados através do teste ANOVA a 1 critério e teste de Dunnett para comparações múltiplas (p=0,05). A análise estatística revelou diferenças significantes (p<0,01) entre os três grupos (grupo controle = 566,73 N; RPE = 409,64 N; e ERA = 410,91 N). Quando as três médias de resistência a fratura são ranqueadas as duas menores não se diferem. Os resultados deste estudo mostraram que uma maior espessura de paredes dentinárias aumenta significantemente a resistência à fratura de dentes tratados endodonticamente.

This study evaluated the fracture resistance of weakened roots restored with glass fiber posts, composite resin cores and complete metal crowns. Thirty maxillary canines were randomly divided into 3 groups of 10 teeth each: teeth without weakened roots (control); teeth with partially weakened roots (PWR) and teeth with and largely weakened roots (LWR). The control group was restored with glass fiber posts and a composite resin core. Teeth in the PWR and LWR groups were flared internally to standardized dimensions in order to simulate root weakness. Thereafter, the roots were partially filled with composite resin and restored in the same way as in the control group. The specimens were exposed to 250,000 cycles in a controlled chewing simulator. All intact specimens were subjected to a static load (N) in a universal testing machine at 45 degrees to the long axis of the tooth until failure. Data were analyzed by one-way ANOVA and Dunnett's test for multiple comparisons (p=0.05). There were statistically significant difference differences (p<0.01) among the groups (control group = 566.73 N; PWR = 409.64 N; and LWR = 410.91 N), with significantly higher fracture strength for the control group. There was no statistically significant difference (p>0.05) between the weakened groups. The results of this study showed that thicker root dentin walls significantly increase the fracture resistance of endodontically treated teeth.

OBJECTIVE: This study evaluated the fracture strengths of endodontically treated teeth restored with prefabricated posts with different post lengths. MATERIAL AND METHODS: Thirty freshly extracted canines were endodontically treated. They were randomly divided into groups of 10 teeth and prepared according to 3 experimental protocols, as follows; Group 1/3 PP: teeth restored with prefabricated post and composite resin core (Z250) with post length of 5.0mm; Group 1/2 PP and Group 2/3 PP: teeth restored with prefabricated post and composite resin core (Z250) with different combinations of post length of 7.5mm and 10mm, respectively. All teeth were restored with full metal crowns. The fracture resistance (N) was measured in a universal testing machine (crosshead speed 0.5mm/min) at 45 degrees to the tooth long axis until failure. Data were analyzed by one-way analysis of variance (alpha=.05). RESULTS: The one-way analysis of variance demonstrated no significant difference among the different post lengths (P>.05) (Groups 1/3 PP = 405.4 N, 1/2 PP = 395.6 N, 2/3 PP = 393.8 N). Failures occurred mainly due to core fracture. CONCLUSIONS: The results of this study showed that an increased post length in teeth restored with prefabricated posts did not significantly increase the fracture resistance of endodontically treated teeth.