O objetivo deste estudo foi avaliar a resistência à fratura de dentes com rizogênese incompleta simulada após diferentes tratamentos intra-radiculares. A rizogênese incompleta foi simulada pelo seccionamento das coroas e raízes de incisivos bovinos. O preparo e alargamento do canal radicular foram realizados utilizando uma broca no sentido coroa-ápice e ápice-coroa. As amostras foram distribuídas (n=10) em cinco grupos: controle positivo (PoC) - sem preparo do canal radicular e sem obturação; controle negativo (NeC) - os dentes foram seccionados e os canais radiculares foram preparados; pino anatômico direto Reforpost #2 (RaP) - pino de fibra de vidro principal + resina composta; pino de fibra de vidro com dupla conicidade (ExP) - pino de fibra de vidro Exacto #3; e pino de fibra de vidro Reforpost #2 + pinos de fibra de vidro acessórios Reforpin (RrP). Nos grupos RaP, ExP e RrP foram realizados plugs apicais de MTA Angelus com 4,0 mm. As amostras foram incluídas em cilindros com resina de poliestireno e o ligamento periodontal foi simulado com material de moldagem à base de poliéter. As amostras foram submetidas ao teste de resistência à fratura, por meio de força compressiva (0,5 mm/min a 135º em relação ao longo eixo do dente) em uma máquina de ensaios mecânicos MTS 810. Os dados foram submetidos à ANOVA a um critério e aos testes para comparações múltiplas Dunnett C ou Tukey HSD (α=0,05). Os grupos controle (PoC e NeC) apresentaram resistência à fratura inferior aos grupos experimentais, sendo o menor valor médio produzido por NeC. ExP produziu os maiores valores de resistência à fratura entre os grupos experimentais. Os procedimentos de preparo e alargamento produziram efeitos prejudiciais na resistência à fratura de dentes bovinos. A utilização de pinos de fibra de vidro intra-radiculares aumentou significativamente a resistência à fratura de dentes com rizogênese incompleta simulada.

The aim of this study was to evaluate the fracture resistance of simulated immature teeth after different intra-radicular treatments. Crowns and roots of bovine incisors were cut transversally and removed to simulate immature teeth. Root canal preparation and flaring were performed using a bur in crown-apex and apex-crown direction. The samples were distributed into 5 groups (n=10): Positive control (PoC) - no root canal flaring or filling; Negative control (NeC) - teeth were sectioned and their root canals were flared; Direct anatomical glass fiber post (RaP) - #2 Reforpost main glass fiber post relined with composite resin; Double tapered conical glass fiber posts (ExP) - #3 Exacto glass fiber post; and #2 Reforpost main glass fiber + Reforpin accessory glass fiber posts (RrP). In RaP, ExP and RrP, 4.0-mm apical plugs were done with MTA Angelus. The specimens were embedded in polystyrene resin inside cylinders and the periodontal ligament was simulated with a polyether-based impression material. The specimens were submitted to compressive fracture strength test (0.5 mm/min at 135° relative to the long axis of the tooth) in a servo-hydraulic mechanical testing machine MTS 810. Data were subjected to one-way ANOVA and Dunnett's C or Tukey's tests (α=0.05). The control groups (PoC and NeC) showed lower fracture strength than the experimental groups. NeC presented the lowest resistance and ExP presented the highest resistance among the experimental groups. The flaring procedures produced a detrimental effect on the fracture resistance of the bovine teeth. Glass fiber intra-radicular posts increased significantly the fracture resistance of simulated immature teeth.

Este estudo avaliou quantitativamente a reparação óssea periapical após cirurgia parendodôntica, utilizando avaliação planimétrica bidimensional (imagens convencionais e digitais intraorais radiográficas-IRs) e tridimensional (CBCT). Onze dentes anteriores da maxila (de 11 pacientes) com lesões ósseas periapicais e indicação de tratamento endodôntico cirúrgico foram selecionados. IRs e imagens tomográficas foram obtidas antes da cirurgia parendodôntica, e 48 h, 4 e 8 meses após a cirurgia. Para cada período, a área (mm2) de rarefação óssea foi mensurada, e os valores para os três métodos comparados. A área nas imagens de CBCT foi mensurada nas seções mésio-distal, compreendendo o maior diâmetro da lesão. Os dados foram submetidos à análise de variância de medidas repetidas a dois critérios e teste T com correção de Bonferroni. Houve diferença significativa entre os períodos de avaliação (p=0,002) em relação à área de lesão óssea periapical mensurada. Não houve diferença significativa entre os métodos de avaliação (p=0,023). Nas imagens tomográficas as áreas das lesões foram 10% maiores do que as observados nas IRs convencionais (22,84 mm2) e 15% maior do que àquelas das digitais (21,48 mm2). A partir dos valores baseline (40,12 mm2) a 4 (20,06 mm2) e 8 meses (9,40 mm2), foram observadas reduções de 50 e 77%, respectivamente, na área das lesões (p<0,0001). De 4 a 8 meses, esse valor foi de 53%. Entre o período de 48h a oito meses após as cirurgias parendodônticas foram observadas reparações ósseas progressivas nas avaliações bidimensionais (IRs convencional e digital) e tridimensional (CBCT). A CBCT produziu resultados semelhantes aqueles avaliados por meio das IRs.

This study quantitatively assessed the periapical bone repair following endodontic surgery, using planimetric evaluation based on two- (conventional and digital intraoral radiographic images - IRs) and three-dimensional (cone beam computed tomography - CBCT) evaluation. Eleven maxillary anterior teeth (of 11 patients) with periapical bone lesions and indication for surgical endodontic treatment were selected. IRs and CBCT images were acquired before the endodontic surgery, and 48 h, 4, and 8-months after the surgery. In each period of evaluation, the area (mm2) of the bone lesion was measured in the images, and the values for the three methods were compared. The area in the CBCT images was measured in the mesio-distal sections comprising the largest diameter of the lesion. Data were submitted to repeated measures 2-way ANOVA and t-tests with Bonferroni correction. There was significant difference between the periods of evaluation (p=0.002) regarding the assessed periapical bone lesion area. There was no statistically significant difference between the methods of evaluation (p=0.023). In the CBCT images the lesion areas were 10% larger than those observed in the conventional IRs (22.84 mm2) and 15% larger than those observed in the digital IRs (21.48 mm2). From the baseline (40.12 mm2) to 4 (20.06 mm2) and 8-months (9.40 mm2), reductions of 50 and 77% in the lesion area, respectively, were observed (p<0.0001). From 4 to 8-months, this value was 53%. Progressive bone repair could be seen from 48h to 8-months following endodontic surgery based on two- (conventional and digital IRs) and three-dimensional (CBCT) evaluation. CBCT images provided results similar to those assessed by means of IRs.

The effect of post-polymerization treatments (MW-microwave irradiation and WB-water-bath) on the degree of conversion (DC) of three reline resins (Ufi Gel hard-U, Kooliner-K, and Tokuso Rebase Fast-T) and one denture base resin (Lucitone 550-L), submitted to two polymerization cycles (LS-short and LL-long), was evaluated by using FT-Raman spectroscopy (n = 5). The molecular weight (Mw) of the powder of all materials and of K polymerized specimens (control; MW; and WB; n = 3) was analyzed using GPC. DC data were analyzed using Kruskal-Wallis test (a = .05). For control specimens, there were no significant differences between U (68%) and LL (77%) and among LL, K (81%), and T (84%). LS (92%) had the highest DC (P < 0.05). Only material K exhibited an increased DC after WB (P < 0.05). All powders had Mw from 4.0 x 10(5) to 6.5 x 10(5) and narrow Mw distributions (2.1 to 3.6). Polymerization and post-polymerization produced K specimens with Mw similar to that of K powder.