To date, there is a theory that increased resistance to caries is observed in the teeth, which for any reason underwent destructive changes in the pulp. That is why there is a need to study the impact of pulp vitality on the development of the carious process. The aim of the research was to study the microscopic structure of epoxy sections of intact and carious third molars. We studied 4 intact and 6 carious third molars. For this purpose, specimens were made taking into account the free penetration of the fixative solution into the pulp. To this end, immediately after the tooth was removed, we cut off its roots almost near the crown, preserving the integrity of the latter. The method relied on the impregnation of specimens with epoxy resin, according to the method of epoxy plastination of tooth specimens, developed at the Department of Human Anatomy of Ukrainian Medical Stomatological Academy. The epoxy blocks were cut with a disk into two halves until the hard tissues of the tooth crown were exposed together with the pulp. We found that the hard tissues (dentin and enamel coating) of intact third molars did not have any structural defects. However, their pulp chamber contained mainly an amorphous substance, devoid of any typical pulp tissue structures. That is, the pulp was in a state of complete devolution. Quite the opposite presentation was observed in specimens of carious teeth. We found that their pulp chamber contained quite noticeable tissue structures typical of the dental pulp. It is interesting that in the subodontoblastic layer, in front of the carious alteration of the enamel, there was compaction of the pulp, which may be due to infiltration of perivascular connective tissue by immunocompetent cells. It was found that on the border with carious destruction of enamel, there was a compacted spot of altered dentin, whose matrix was intensely pigmented in brown colour, due to the accumulation of melanin on the dentino-enamel junction. Its excessive formation is associated with the destruction of protein-carbohydrate complexes of organic matter in the deep layers of dentin. We found that the pulp compaction and the focus of carious alteration of the enamel are projectively connected by a radial cord of altered dentin, known in the literature as “dead tracts”. Hence, there is reason to believe that the identified changes indicate a latent form of caries, with a pulpogenic mechanism of development. Thus, it can be argued that the teeth, which for any reason underwent degenerative changes in the pulp, are not prone to carious lesions, whereas in carious teeth, the pulp is active and involved in the pathogenesis of the carious process.
The article presents a theoretical synthesis and a new solution of the scientific problem, which consists in determining the sexual and individual polymorphism of third molars through the age aspect. The review of the relevant literature, the results obtained by analysing orthopantograms of people at the first period of adulthood, and studying randomly selected third molars removed for various clinical reasons (more than 140 samples) are presented. It has been shown that erupted third molars considerably vary in size and shape that is due to different combinations of configurational relationship between the crown and root parts. This depends on the location of opposing teeth in the dentition and sex as well, but does not correlate with age. Moreover, the entire range of individual and sexual variability of the third molars is limited by two extreme forms: very large teeth with long divided roots or with a quadratubercular crown, which are not significantly different from typical molars, and very small analogues with one fused root section, the crowns of which resemble small permanent teeth. Between these forms all other are distributed and most numerous types we called as intermediate. The data analyzed indicate that the individual variability of the size of the teeth in length depends entirely on the length of their root sections. It has been established that, relative to the crown-root index, there are three forms distinguished among the third molars: long-root; medium root and short root. At the same time, long-root forms are found mainly among male teeth, mid-root forms are more characteristic of female wisdom teeth, and short-root forms of third molars do not show a sex difference. The results obtained demonstrate that the orthopantogram of the dentofacial system in humans (aged 22 to 35 years) reliably reveals an inverse relationship between the longitudinal size and the term of eruption of the third molars. The systematic approach used in the work made it possible to bring the varied polymorphism of the third molars into a certain order, highlighting the most indicative features for their classification.
This article presents a literature review, the results of the analysis of random samples of third molars removed for various clinical indications (11 samples). The teeth samples were analyzed visually, then their coronal parts were treated with epoxy plastination technique and prepared polished sections were studied microscopically. The analyzed data demonstrate the pathogenesis of fissure caries in our samples studied can be explained in terms of the direct virulent effect of pathogenic bacteria on the organic matter in the superficial dentin and basal enamel with the formation of auto antigens, which, as a result of sensitization of the local immune system, become the initial source of the carious process spreading to other teeth. This gives grounds to identify it with the pathogenesis of autoimmune pathology. It has been established that carious damage to hard tissues on the smooth surfaces of the dental crown begins with the pulp, when it is vital, and stops as a result of its tissue degeneration. It has been shown that a single latent damage to the hard dental tissues is the initial manifestation of the latent stage of the carious process, while multiple defects indicate its further progression. As for the generally accepted classification of caries, according to which superficial, medium and deep caries are distinguished, then, in our opinion, they should be considered as stages of the further process of carious destruction of hard dental tissues. We can suggest the study of the pathogenesis of carious lesions of third molars is necessary in order to prevent the occurrence of autoimmune diseases and increase the effectiveness of their treatment.
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