Histological and morphometric specifics of the jaw alveolar process bone tissue in individuals with connective tissue dysplasia symptoms

Aim of the study: to identify histological morphometric features of the jaw bone tissue and vascular system in individuals with undifferentiated connective tissue dysplasia (UCTD) syndrome to improve the efficiency of pathomorphological diagnostics of the congenital disorders affecting connective tissue development.

Material and methods. Histological and morphometric studies of bone preparations were done using sectional material obtained from 34 authenticated subjects aged 36-60 with preserved lower jaw dentition. The study was carried out at 36th and 46th teeth projection involving the assessment of the periosteum, as well as the compact and the spongy bone layers. The individuals were divided into two groups: Group 1 (n=15) – those with no background pathology; Group 2 (n=19) – individuals with UCTD syndrome revealing at least 6 locomotor and locomotorvisceral signs with at least 2-3 organs affected. While studying the microstructure, the preparations were stained with hematoxylin and eosin, picrofuchsin (according to Van Gieson); for the morphometric evaluation of bone tissue and vascular system, quantitative parameters (the compact substance proportion; the spongy substance proportion; the number of vessels; the number of Haversian canals; the diameter of vessels; the diameter of Haversian canals; the vascular wall thickness; the proportion of osteoblasts; the proportion of osteocytes and the proportion of osteoclasts), the ImageJ software was used.

Results. Deteriorating qualitative indicators of the jaw histology and angio-architectonics in UCTD manifest by the following changes: areas featuring disoriented bar structures; enlarged and deformed osteocytes with nuclei located in the peripheral areas; dystrophic changes in osteocytes; depleted cellular and vascular pattern; increased extracellular matrix volume; expanded Haversian osteons; vascular bed multiplications and twisting; autolytic resorption foci with axillary resorption type; thickening, curvatures, disturbed spatial connection of collagen fibers; thin-walled veins with a sharp increase in the diameter; thickened walls of arterial vessels with a decrease in their lumen; venous malformation areas; vessels revealing signs of endotheliosis. Quantitative changes in individuals suffering from UCTD syndrome demonstrate the following (according to Me) compared with the data in persons with no background pathology: a decrease in the compact substance proportion (2.14-fold); an increase in the spongy substance content (1.42-fold); a decrease in the number of blood vessels (1.56-fold) with a decrease in their diameter (1.54-fold); an increase in the vascular wall thickness (2.27-fold); a decrease in the number of Haversian canals (1.44-fold) with their diameter increase (2.25-fold); an increase in the proportion of osteoblasts (3.54-fold); a decrease in the osteocyte content (1.78-fold).

Conclusion. The identified changes involving the morphology and microscopic angio-architectonics of the jaw bones in individuals with UCTD syndrome point at incomplete maxillofacial bone maturation processes; progression of degenerative and sclerotic changes typical of osteoporosis; slowed local microcirculation, also reflecting the specifics of connective tissue metabolism in case of collagenopathies. It would be reasonable to review the entire set of therapeutic, preventive, and rehabilitation measures in this category of patients to correct metabolic issues related to osteopenia and increase the mineral saturation and hardness of bone tissue.

Key words: connective tissue dysplasia, angio-architectonics of the alveolar process, histological structure of the alveolar process, pathomorphological studies, histological morphometric studies, bone tissue.

Conflicts of interest. The authors have no conflicts of interest to declare.

Funding. There was no funding for this study