Effects of Internal Bleaching on the Adhesion of Glass-Fiber Posts.

OBJECTIVE: We evaluated the effects of internal bleaching on the adhesion of glass-fiber posts (GFPs) luted with different resin cements. METHODS: Forty extracted human single-root teeth were endodontically treated and divided into four groups (n=10): G1- conventional resin cement (CRC); G2- self-adhesive resin cement (SARC); G3- bleaching + CRC; and G4- bleaching + SARC. Specimens were sectioned transversally into three slices to perform the push-out test at the coronal, middle and apical regions of the root canals. Data were analyzed using analysis of variance and Tukey's test (p<0.05). RESULTS: The push-out bond strength of GFPs luted with SARC after bleaching (G4) was significantly lower than that of the other groups (p<0.001). We found no statistically significant differences in push-out bond strength among the other groups. SIGNIFICANCE: Internal bleaching reduced the adhesion of GFPs luted with SARC. The adhesion of GFPs luted with CRC was not decreased after bleaching.

Effects of 3-dimensional conformal or intensity-modulated radiotherapy on dental pulp sensitivity during and after the treatment of oral or oropharyngeal malignancies.

INTRODUCTION: Radiation therapy (RT) of malignant tumors in the head and neck area may have damaging effects on surrounding tissues. The aim of this investigation was to evaluate the effects of RT delivered by 3-dimensional conformal radiotherapy (3D-RT) or intensity-modulated radiotherapy (IMRT) on dental pulp sensitivity. METHODS: Twenty patients with oral or oropharyngeal cancer receiving RT with 3D-RT or IMRT underwent cold thermal pulp sensitivity testing (PST) of 2 teeth each at 4 time points: before RT (TP1), the beginning of RT with doses between 30 and 35 Gy (TP2), the end of RT with doses between 60 and 70 Gy (TP3), and 4 to 5 months after the start of RT (TP4). RESULTS: All 40 teeth showed positive responses to PST at TP1 (100%) and 9 at TP2 (22.5%; 3/16 [18.8%] for 3D-RT and 6/24 [25.0%] for IMRT). No tooth responded to PST at TP3 and TP4 (0%). A statistically significant difference existed in the number of positive pulp responses between different time points (TP1 through TP4) for all patients receiving RT (P ≤ .05), IMRT (P ≤ .05), and 3D-RT (P ≤ .05). No statistically significant differences in positive sensitivity responses were found between 3D-RT and IMRT at any time point (TP1, TP3, TP4, P = 1.0; TP2, P = .74). A statistically significant correlation existed between the location of the tumor and PST at TP2 for IMRT (P ≤ .05) but not for 3D-RT (P = .14). CONCLUSIONS: RT decreased the number of teeth responding to PST after doses greater than 30 to 35 Gy. The type of RT (3D-RT or IMRT) had no influence on the pulp responses to PST after the conclusion of RT.

Efficacy of sodium hypochlorite, ethylenediaminetetraacetic acid, citric acid and phosphoric acid in calcium hydroxide removal from the root canal: a microscopic cleanliness evaluation.

Rooted molars were subjected to standardized canal instrumentation to a master apical file (MAF). The samples were dressed with Ca(OH)(2), and after 7 days, teeth were reopened and Ca(OH)(2) medication was removed by 1 of 4 different experimental procedures: 2.5% sodium hypochlorite (NaOCl) (n = 10); 17% EDTA-T (n = 10); 10% citric acid (n = 10); or 37% phosphoric acid (n = 10). This was followed by reinstrumentation with MAF plus 15 mL saline solution. The roots were prepared for scanning electron microscopic analysis of the cervical, middle, and apical thirds. Statistical analysis was performed with the Kruskal-Wallis test. EDTA-T and phosphoric acid gave the best results in the apical third, with significant statistical differences compared with other groups. NaOCl gave the worst results. Irrigation with 17% EDTA-T and 37% phosphoric acid is more effective than sodium hypochlorite and citric acid in the removal of calcium hydroxide from the apical third.

Método para o ensino de endodontia laboratorial: plataforma radiográfica para canais simulados / Method for teaching endodontic laboratory: the radiographic platform for simulated root canals

O preparo do canal radicular tem sido avaliado por diferentes métodos ao longo dos anos: a microscopia ótica, a microscopia eletrônica de varredura, o exame radiográfico, analises fotográficas, moldagem, os métodos computadorizados e recentemente a análise tomográfica. Até 1987, a grande dificuldade na avaliação estava na ausência de um controle negativo uma vez que o preparo só podia ser avaliado após a instrumentação. Neste ano, Bramante et al. desenvolveram um método que permitiu a análise antes e após o preparo, usando dentes incluídos em resina e em morsa adequada e seccionados transversalmente, o qual se tornou o mais importante método para análise da qualidade do preparo do canal radicular. Em 1991 Sydney et al.3, desenvolveram uma plataforma radiográfica com a finalidade de padronizar as tomadas radiográficas, obtendo numa mesma película as imagens dos instrumentos antes e depois da instrumentação, para em seguida analisar a manutenção do trajeto original do canal radicular ou não. Face às restrições no uso de dentes naturais e as dificuldades de sua obtenção, o ensino básico da endodontica viu-se obrigado a buscar alternativas. Dente estas, o uso de canais simulados tem se mostrado uma opção de grande valia o que gerou ao desenvolvimento de uma plataforma radiográfica específica para estes, tornando-se valioso auxiliar no ensino da Endodontia.

Root canal preparation has been evaluated by different methods along the years: common optical microscope, the scanning electron microscope, radiographic examination, photographic studies, root canal models, computer programs and recently the tomography. Until 1987 the difficulty on analyzing root canal preparation was the negative control. In this year, Bramante et al. introduced a method that allowed the analysis before, during and after instrumentation. In 1991 Sydney et al.3 developed the radiographic platform method that makes possible to get in the same film the position of the file at the beginning and at the end of instrumentation. Deviations and imperfection are directly observed. The importance of simulated root canals in teaching endodontics is significant as we have difficulties and restrictions on getting human tooth for the grad students. The development of a radiographic platform for simulated root canals is an important teaching aid in endodontics.

Microscopic cleanliness evaluation of the apical root canal after using calcium hydroxide mixed with chlorhexidine, propylene glycol, or antibiotic paste.

This study evaluated cleaning of the dentinal wall after removal of different calcium hydroxide pastes. Sixty-eight single-rooted teeth were prepared using the step-back technique and randomly divided into 4 groups according to medication used: Ca(OH)2 with 0.2% chlorhexidine solution (Group 1), Ca(OH)2 with propylene glycol (Group 2), Ca(OH)2 with antibiotic paste (ciprofloxacin, metronidazole) and distilled water (Group 3), and Ca(OH)2 with antibiotic paste and propylene glycol (Group 4). The samples were stored at 37 °C and 100% relative humidity for 21 days. The medicaments were removed using 5 mL 1% NaOCl, instrumentation with master apical file, 5 mL 1% NaOCl, patency with the K-file #10, ultrasonic instrumentation, and 10 mL 17% EDTA-T. The specimens were analyzed using scanning electron microscopy and chemical analysis. The Kruskal-Wallis (α = 5%) test showed that were no differences between the experimental groups when comparing Ca(OH)2 removal (P = .0951). The chi-square test (α = 5%) indicated a predominance of Ca(OH)2 obstructing dental tubules in all groups. On the basis of the methodology applied, it was concluded that the apical dentine surface remained equally covered by Ca(OH)2, regardless of the vehicle used.