Marco Abdo Gravina

Apical root resorption: the dark side of the root.

INTRODUCTION The diagnosis of apical root resorption is usually based on routine radiographs. However, these methods are limited because the images reflect the superimposition of the whole root structure and can lead to underestimation of the extent of apical root resorption. In this study, we aimed to determine the lengths of the labial and lingual surfaces of incisors with apical root resorption and compare them with the longest radicular length obtained on sagittal images of cone-beam computed tomography, and to create a qualitative visual scale of the different patterns of apical root resorption. METHODS Eighty-two incisors with apical root resorption from 25 patients had their labial and lingual root surfaces and the longest radicular lengths determined in the sagittal plane and compared. Five orthodontists, at 2 times, classified the images of each incisor according to a visual scale developed by the authors. RESULTS There was no significant difference between the labial and lingual surfaces; however, the longest radicular length was significantly greater than the shortest surface length. The visual scale showed intraobserver agreement of 0.615 and interobserver agreements of 0.74 and 0.52 at both times, respectively. CONCLUSIONS The difference between the longest and shortest root lengths suggests that radiographic superimposition underestimates the extent of the resorption lesion. The proposed visual scale showed a frequency of agreement above 65% and a coefficient of reproducibility varying from moderate to substantial.

The role of orthodontic tooth movement in bone and root mineral density: A study of patients submitted and not submitted to orthodontic treatment

Summary Background Orthodontic force application to the teeth is responsible for a series of biological responses in the bone and dentin, which lead to some alterations of the mineral density of the tissues. Our objective was determine, through cone-beam computed tomography (CBCT), the mineral density of the apical third of the roots of the upper central incisors and of the periapical bone portion surrounding these teeth, in patients submitted to orthodontic treated and untreated individuals. Material/Methods 30 untreated individuals and 15 treated ones (treatment cessation at least 1 year before the study) underwent CBCT. Mineral density was assessed in the apical third of the root of the upper central incisors and in the alveolar bone in the periapical region of these teeth. In order to reduce CBCT-related mineral density variability, we standardized the cone-beam tomography device, the image-acquisition settings and the field of view positioning and size. Student’s t test was used for the analyses. Results bone mineral density (BMD) and root mineral density (RMD), in Hounsfield Units, were 674.84 and 1282.26 for the untreated group and 630.28 and 1370.29 for the treated group, respectively. The differences between the group means were statistically significant for RMD (p<0.05). Conclusions untreated individuals had a significant lower mean RMD in comparison with those submitted to orthodontic treatment.

Shear bond resistance and enamel surface comparison after the bonding and debonding of ceramic and metallic brackets

Objective To evaluate, in vitro, the shear bond strength presented by three brands of polycrystalline ceramic brackets and one brand of metallic bracket; verify the adhesive remnant index (ARI) after the tests, and analyze, through scanning electron microscopy (SEM) the enamel surface topography after debonding, detecting the release of mineral particles. Methods Sixty bovine lower incisors were used. Three ceramic brackets (Allure®, InVu®, and Clarity®) and one metallic bracket (Geneus®) were bonded with Transbond XT®. Kruskal-Walliss test (significance level set at 5%) was applied to the results of share bond and ARI. Mann Whitneys test was performed to compare the pairs of brackets in relation to their ARI. Brown-Forsythes test (significance level set at 5%) was applied to the results of enamel chemical composition. Comparisons between groups were made with Games-Howells and the Post-hoc tests. Results No statistically significant difference was observed in relation to the shear bond strength loads. Clarity® brackets were the most affected in relation to the surface topography and to the release of mineral particles of enamel (calcium ions). Conclusion With regard to the ARI, there was a prevalence of score 4 (40.4%). As for enamel surface topography, the Geneus® bracket was the only one which did not show superficial tissue loss. The InVu® and Clarity® ones showed cohesive fractures in 33.3% and the Allure® in 50%, the latter being the one that presented most fractures during removal.

Prototype of a new tip developed to be coupled to dental light-curing units for optimizing bonding of orthodontic brackets and accessories

OBJECTIVE Development of a new device to be coupled to light-curing units for bonding orthodontic brackets and accessories, and test its efficacy in an in vitro mechanical trial. The inner surface of the device is mirrored and is based on physical concepts of light refraction and reflection. The main advantage of such device is the reduced clinical time needed for bonding and the low possibility of contamination during the process. METHODS One hundred and twenty specimens were used for testing the shear bond strength of brackets bonded with the device. The Adhesive Remnant Index (ARI) was also determined. The sample was divided into 2 groups. In group 1 a halogen light-curing unit was used while in group 2 a led light-curing unit was used. Each group was then subdivided. In subgroups H1 and L1, a conventional light guide rod was used while in subgroups H2 and L2 bonding was performed with the mirrored device coupled to the tip of the guide light rod. RESULTS The values obtained for the shear bond strength and the ARI in the subgroups were compared. Results showed that there was no statistically significant difference for the shear strength (p > 0.05) and the ARI (p > 0.05) between the subgroups. CONCLUSIONS The tests of mechanical trials and the ARI analysis showed that the new device fulfilled the requirements for bonding orthodontic accessories, and that the time for bonding was reduced to half, being necessary only one light exposure.

Estudo dos Determinantes Cefalométricos da Relação ÂnteroPosterior Maxilomandibular em Amostra de Oclusão Normal

Objetivo: Comparar os valores das medidas utilizadas na analise da relacao ântero-posterior maxilomandibular (ANB, AF-BF, Wits, TPi e FABA) com seus respectivos padrao de normalidade; determinar o grau de correlacao entre estas medidas; avaliar a presenca de dimorfismo sexual.Metodo: Foram utilizadas 23 telerradiografias em norma lateral de brasileiros portadores de oclusao clinicamente normal com idade acima de 18 anos e o sexo escolhido ao acaso. Os valores foram avaliados entre si e comparados com o padrao para cada medida utilizando-se o teste t-student com nivel de significância de 5%, bem como determinacao do grau de correlacao de Pearson entre as medidas para ambos os sexos e avaliacao do dimorfismo sexual atraves do teste Kruskal-Wallis assumindo o nivel de signifcância de 5%. Resultados: Para o sexo masculino, as medidas AF-BF e TPi apresentaram valor p0,05.Conclusao: As medidas AO-BO, ANB e FABA dos individuos do sexo masculino da amostra estudada nao apresentam diferenca estatisticamente significativa em relacao aos valores padrao. Ja para os individuos do sexo feminino da amostra, nao houve diferenca estatisticamente significativa em relacao aos valores padrao para as medidas AF-BF, AO-BO, ANB e FABA; existe um alto grau de correlacao entre as medidas TPi, AO-BO e ANB para o sexo masculino e TPi, AOBO, ANB e FABA para o sexo feminino; nao houve dimorfismo sexual para nenhuma das medidas estudadas (AU) Objective: To copare the values of the measurements used in the analysus of the anteroposterior maxillomandibular relationship (ANB, AF-BF, Wits, TPi and FABA) with standard values of normality; to evaluate the degree of correlation between the measurements; to evaluate the presence of sexual dimorphism for each measurement in the sample under study.Method: Twenty three lateral cephalometric radiographs of Brazilian individuals with normal occlusion, over 18 years of age, with sex randomly selected, were taken. The values were evaluated between them and compared with the standard values for each measurement using t-Student test with significant at the 5% level of significance, as well as the determination of the degree of Pearsons correlation between the measurements for both sexes, and the evaluation of sexual dimorphism throught Kruskal-Wallis test at the 5% level of significance.Results: For the male sex, the measurements AF-BF and TPi showed value p0,05.Conclusion: The measurements AO-BO, ANB and FABA of the male subjects did not show statistically significant difference when compared to standard values. As for the female individuals, there was no significant difference relative to standard values for the AF-BF, AOBO, ANB and FABA measurements. There is a high degree of correlation between the TPi, AO-BO and ANB measurements for males and TPi, AOBO, ANB and FABA for females. No sexual dimorphism was noticed in any of the studied measurements (AU)