Freqüência clínica dos biótipos periodontais considerando o formato geométrico dos incisivos centrais superiores / Clinical frequency of periodontal biotypes among different geometric forms of maxillary incisors

O objetivo deste estudo clínico foi avaliar a freqüência dos biótipos periodontais, considerando os diferentes formatos geométricos dos incisivos centrais superiores, através de parâmetros anatômicos dentários e gengivais. Quarenta voluntários foram agrupados de acordo com a forma dos incisivos centrais superiores (ICS, n = 10): retangular (grupo 1), triangular (grupo 2), quadrado (grupo 3) ou oval (grupo 4). Para cada voluntário, foi determinado o biótipo periodontal através de consenso entre 3 examinadores calibrados e foram medidos: o comprimento (CC) e a largura (LC) da coroa; a razão entre a largura e o comprimento da coroa (PLC); a altura do ponto de contato entre os ICS (APC); a distância entre os zênites gengivais dos ICS (ZG1); a distância entre os zênites gengivais do incisivo central e do incisivo lateral superiores (ZG2); a altura da papila entre os ICS (AP1); e a altura da papila entre o incisivo central e o incisivo lateral superiores (AP2). Os dentes quadrados obtiveram os menores valores de comprimento coronário (9,36 ± 0,97, p = 0,0012) e a maior proporção entre a largura e o comprimento da coroa (0,93 ± 0,06, p = 0,0001), quando comparados aos dos demais grupos. Os dentes triangulares apresentaram significativamente a maior distância (8,44 ± 0,89, p = 0,0438) considerando o parâmetro ZG2. O biótipo periodontal fino/festonado foi predominante no total de voluntários desse estudo (60%), e mais freqüente em indivíduos com dentes retangulares. Voluntários com dentes quadrados apresentaram maior freqüência de periodonto plano e espesso (60%), embora o teste exato de Fisher não tenha encontrado diferenças estatisticamente significantes entre os grupos.

The aim of this clinical study was to evaluate the frequency of periodontal phenotypes among different geometric forms of maxillary central incisors. Some clinical parameters such as tooth and papillae dimension, localization of contact points and distances between gingival vertices were also evaluated. Forty patients were selected and divided into 4 groups (n=10) according to geometric form of maxillary central incisors: rectangular (group 1), triangular (group 2), squared (group 3) or ovoid (group 4). Squared teeth showed the lowest coronal length values (9.36±0.97; p=0.0012 and the highest coronal width/length ratio (0.93±0.06; p=0.0001), when compared to the other groups. Thin and scalloped gingival phenotype was predominant in this clinical study (60%), and was frequent in groups 1, 2 and 4. In contrast, squared teeth (group 3) presented predominantly thick and plan gingiva. Nevertheless, Fisher’s exact test did not found any statistical difference among groups.

Microleakage at the composite-repair interface: effect of different surface treatment methods.

This study evaluated microleakage at the composite-repair interface after using different methods of surface treatment. Eighty resin composite specimens (Filtek Z250, 3M Dental Products) aged in artificial saliva for three months were divided into four groups (n=20) according to the following surface treatment methods: untreated control-no roughening or abrasion of the surface; roughening with diamond burs; jet prophylaxis with sodium bicarbonate particles and air abrasion with 50 microm aluminum oxide particles. Each method was examined using scanning electron microscopy (SEM) to evaluate changes in surface topography. All groups were then etched with 37% phosphoric acid, coated with a bonding agent (Single Bond, 3M Dental Products) and received new resin applications. The samples were then thermocycled (800 cycles/5 degrees C to 55 degrees C [+/- 2]) and immersed in 2% methylene blue buffered dye solution (7.0 pH) for four hours. Three examiners measured the extent of microleakage in a stereoscope microscope using four representative scores. For all experimental groups, no significant difference in repair microleakage was identified by the Kruskal-Wallis test (p>0.05). Therefore, different testing methods of surface treatment showed the same effect on dye penetration along the repair interface.