[Biomechanics of orthodontic movement--initial response of periodontal tissue]. / Biomecánica da movimentação ortodôntica--resposta inicial dos tecidos periodontais.

There occurs a biological response of the tissues of dental support, in answer to the external physiological forces and those realized during clinical treatments with orthodontical purposes. These forces differ from the first ones because they are continuous and time dependent. A great dental mobility is related to the degree of tissue organization of the periodontium system and the orthodontical movement must utilize this exceptional capacity of renewal and adaptation of the periodontium structures adequately. Therefore, through histological means a search was made to evaluate the succession of alterations of the periodontium system after the application of an orthodontical force on the molars of young rats and to interpret the standards of horizontal mobility and their consequences on the periodontium structures, biologically. An orthodontic force was applied on young rats utilizing steel wire placed in a ring form on a contact point between the first and second lower molars. The animals were sacrificed after 30 minutes, 1, 2, 6, 12, 24, 48, 72, 96 and 168 hours after the placement of the metal ring. After technical preparation, the microscopic slides were examined and the results were compared. In all the sections there was evidence of an intense metabolic activity. A gradual evolution of modification on the phenomenons had occurred.

[Comparative histological study of palatal mucosa in patients with and without complete dentures before and after insertion of new dentures]. / Estudo histológico comparativo da mucosa palatina em pacientes portadores e não portadores de próteses totais antes e após a instalação de novas proteses.

The authors verified histologically in 20 no dentates patients, the influence of complete dentures on the hard palate mucosa. The patients were divided in two groups: I. Patients that never used complete dentures; II. Patients that were using complete dentures when this research was realized. New prosthesis were made for each one of the 20 patients. Immediately before they received the new prosthesis and ninety days after this, biopsies were realized. The circunferencial pieces of the hard palate mucosa were fixed in formol 10% and coloured with Hematoxylin/Eosin and Mallory's Tricomic for histomorphologic analysis and measuring of the stratum corneum of the epithelium. It was made the statistical analysis and the results showed that: 1. In normal conditions, the utilization of the full dentures produces the reduce of the thickness of the stratum corneum. This was more observed in Group I. 2. The range difference of the thickness of the stratum corneum between the first and the second biopsies in the groups I and II (4.86 microns and 2.18 microns) were not statistically significant. 3. With the use of complete dentures the stratum corneum of the epithelium showed tendence to parakeratinization.