Smaglyuk L. V., Shundrik L. S.

CONTENTS

Scentific article

Currently the use of fixed orthodontic appliances for treatment of anomalies and deformations of the occlusion is taking the leading position. The main part of success in orthodontic treatment is reliable fixation of the bracket, which depends on the optimal choice of the adhesive system, strict compliance with the sequence of ma-nipulations at work with it, the condition of the tooth enamel used for fixation. Dental fluorosis is commonly known to be widespread in many parts of the Poltava region. This fact is due to the high fluorine content in the environment, which leads to destructive changes of both the enamel and the dentine. The prevalence of dentofacial anomalies in regions with high fluorine content can be up to 84,6 %. It can be sup-posed that the degree of adhesion of the adhesive system to the enamel of a tooth affected with fluorosis will reduce in comparison with the intact enamel. The level of changes in the surface structure of the tooth enamel after acid etching depends on the time of exposure, chemical composition, acid concentration and the structure of hard tissues. However, there is no reli-able information regarding features of morphological changes of the enamel in preparation of a tooth affected with fluorosis for fixation of the bracket. The purpose of our work was to determine factors which provide amplification of the mechanisms for fixing the bracket in orthodontic patients affected with fluorosis. 48 patients affected with fluorosis were taken for orthodontic treatment. Thirty premolars extracted for orth-odontic purposes were used in the morphological research. There were 16 premolars affected with fluorosis and 14 premolars without signs of fluorosis. 37 % orthophosphoric acid in gel was used as an etchant. Light curing orthodontic adhesive Transbond XT (3M Unitek, Monrovia, California, USA) was used in the course of the research. While a tooth was prepared for fixation of the bracket, time of exposure to etching was changed from 30 to 50 sec-onds and time of exposure to drying after washing was changed from 15 to 30 seconds. Thin sections by Kostilenko Y. P. method were prepared for morphological research. Tooth research was per-formed with the help of light and scanning microscopy SEM-102E with high voltage of 30 kV. Сonclusions. Premolars enamel has a composite structure formed by complex interweaving of three divergent sets of crystal fibers. Compositional density between different groups in the crystal fibers enamel thickness gradu-ally increases from the border dentine zone to the most superficial layer. Adhesion between the outer surface of the enamel and adhesive Transbond XT occures at the expense of inter-molecular interactions between their adjacent contact surfaces. By increasing time of the enamel acid etching the degree of coupling between the contact surface and enamel adhesive improves by increasing the width of the gap separating them. The width of the gap between the contact surface of the enamel affected by fluorosis with adhe-sive Transbond XT is usually more than the norm, which reduces the fixing properties of the adhesive.

enamel, fluorosis, adhesive, bracket fixation

«Bulletin of problems biology and medicine» Issue 2 part 2 (108), 2014 year, 152-156 pages, index UDK 616. 314. 13+616. 314–089. 23