Evaluation of the influence of connective tissue dysplasia on morphologic and biochemical rearrangements in the organic and mineral matrix of lower third molars at different stages of eruption

Abstract

Purpose of the work is to evaluate the maturity of the hard tissues of the lower third molars at different stages of eruption in connective tissue dysplasia, based on the results of microscopic and biochemical methods.
Material and methods.
The study involved 84 women in the age groups 14—17, 18—21, 22—26, 27—31, 32—36 years with and without connective tissue dysplasia who had teeth 38, 48, which were at different stages of eruption, extracted for orthodontic or emergency indications. After preparation of dentin, enamel and enamel-dentin junction samples according to our own methods, microscopic examination was carried out using a scanning electron microscope Jeol JCM-5700, the morphology of dental hard tissues was evaluated on a longitudinal section, as well as biochemical examination by IR spectroscopy, the position and intensity of absorption bands (AB) were determined at all stages.
Results.
Statistically significant differences between age groups in CTD were found in the superficial section: in the age group 22—26 years at the stages of rudiment (p=0.0001), up to the gingival level (p=0.02), up to the level of the crown of the second molar (p=0.002); in the age group 14—17 years at the stage of eruption up to the level of the crown of the second molar (p=0.0200). In the deep section, differences were established only at the age of 14—17 years at the stage up to the level of the crown of the second molar (p=0.0200). The intensity of AB phosphate (967 cm−1) decreases in CTD at all stages of eruption except for the rudimentary stage, but it is at this stage that the intensity of AB 1050 cm−1 also decreases, which generally indicates a decrease in the mineral content of dental hard tissues in CTD. The AB intensity of collagen (1202 and 1249 cm−1) in CTD increases in dentin and decreases in enamel.
Conclusions.
The results of microscopic and biochemical examination of the hard tissues of lower third molars show that the presence of collagen fibers in dentin affects the biochemical and mechanical properties of enamel through enamel-dentin junction, due to strong adhesion and proper packing of collagen fibrils.