Ultrastructural arrangement and elemental composition of baby teeth enamel through physiological change period

Aim of study. This study aimed to examine the specific features of the microscopic structure and the chemical elements of the teeth enamel in children through physiological tooth change, which stand behind low level of resistance to caries.
Materials and methods. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy were employed through the study to examine the structure as well as the elemental composition of the enamel on baby teeth removed subject to clinical indications. Extirpated baby teeth (n=175), taking into account respective histomorphological features, were divided into two groups, namely, Group 1, which were molars (n=80) with a so-called mature enamel structure and fully developed roots (children aged 48-54 months); Group 2 – molars (n=80) going through the stage of involutive processes involving the enamel and featuring resorbable roots (children aged 84-132 months). The extracted teeth were decalcified for a histological study, put in a Histomix medium, followed by preparation of serial sections and staining with hematoxylin and eosin. The samples were examined with a Leica DM4000 B LED microscope (magn. ×20-×1000). In Group 1 (n=15), the acid resistance of the enamel on the teeth to be extracted was identified with the enamel resistance test (ERT) (V.R. Okushko, 1984).
Results. The low level of acid resistance of the enamel on intact teeth in children with absorbable roots in the second period of lactic bite has been proven to be due to the following changes in the tooth enamel morphology and chemical composition: tightly fixed plaque; disturbed structural arrangement in the intact enamel so-called islands (hypo- and demineralized areas; granular texture, porosity, porous surface; destroyed enamel prisms; destroyed interprism substance; disoriented apatite crystals; oblique enamel prisms; issues manifested like cracks and cavities with scalloped edges running through the entire enamel layer); increased concentration of organic matrix due to low mineralization; decreased share of trace elements (by IU) (F – 0.012 % wt, Zn – 0.07 % wt); reduced enamel layer (down to 0.43 ± 0.14 mm) along with expanded interprism spaces (up to 1.87 ± 0.36 microns; p≤0.05); Ca /P molar coefficient value of 1.39 with a concentration of Calcium and Phosphorus in the enamel at 18.13 % wt and 13.07 % wt, respectively.
Conclusion. Involutive changes through the second lactic bite period occurring against suppressed synthetic activity of odontoblasts, lack of replacement dentin and structural and functional instability of the enamel layer – all these contribute to the development of issues affecting the enamel surface. Lengthy accumulation of dental plaque, disturbed integrity of thinned enamel, a high share of organic matter with weak mineralization and erosion of the enamel layer, as well as a scalloped enamel-dentine border, will reduce the baby teeth resistance to aggressive factors to be found in the oral cavity, as well as will make the respective tissues vulnerable to the carious process.
Keywords: baby teeth, enamel, caries resistance, acid resistance of enamel, elemental composition, X-ray spectral analysis, scanning electron microscopy.
Conflicts of interest. The author have no conflicts of interest to declare.
Funding. There was no funding for this study.