Structural and microelemental changes in enamel under the influence of various methods of preparation

Abstract

Previous scientific researches and obtained practical results show that the choice of the optimal technology of odontopreparation is still a subject of further scientific research. Objective — To study in vitro influence of methods of odontopreparation on the surface of enamel, its structure, qualitative and quantitative composition of microelements at the stages of preparation of teeth for microprosthetics. >. 45 samples of teeth extracted for orthodontic and prosthetic indications and prepared by a special technique were studied. They were divided into 3 equal groups according to the method of preparation: Group I — intact enamel, II — preparation with diamond burs, III — air abrasion. The enamel surface of the specimens was examined under a scanning electron microscope with a magnification from 400 to 6000 times. Micro X-ray spectral analysis with determination of mass fractions of C, O, Na, Mg, Al, Ca and P was carried out. >. In intact tooth samples, enamel is characterized by a homogeneous surface structure against the background of its stable quantitative and qualitative microelement composition. On the surface of enamel affected by mechanical influence of various methods of preparation (use of diamond drills and aeroabrasion), disturbances of various degree of expressiveness are observed: from insignificant grooves of the size of 5 µm (III group) to wavy — 5—60 µm, with the presence of horizontal microcracks, fragments of enamel prisms, with traces of diamond splashes from repeated unidirectional movements of drill facets (II group). At the same time in group II against the background of increase in the proportion of calcium from 32.56 to 34.48% and phosphorus from 12.42 to 14.99% slightly decreased the amount of carbon, magnesium and aluminum (by 0.49, 0.36 and 0.30%, respectively) in comparison with group I. In group III there is an increase in the proportion of oxygen from 32.66 to 36.06% and phosphorus from 12.42 to 15.14% against the background of negative dynamics of carbon, magnesium and aluminum. Comparative analysis of the results of biological samples showed a 1.3-fold decrease in carbon content and a 1.85-fold increase in magnesium content in group III compared to group II. >. During odontopreparation with minimally invasive ceramic restorations, the enamel surface changes, its structure is altered, and the balance between the quantitative and qualitative microelement composition changes, the degree of which depends on the preparation method. In this case, preparation of the tooth by air abrasion is more gentle in terms of preserving the enamel structure, but less stable in terms of quantitative trace element composition.