The aim: The paper was aimed at the study of the processes of mineralization of the enamel of the permanent tooth after its eruption. Materials and methods: To study the structure of the enamel of permanent teeth has been carried out using light and electron microscopy. The study of the process of the development of the primordia of the permanent teeth involved 10 culled puppies of 30-40 days of age. Microscopic, electron microscopic, immunohistochemical methods of research have been used to study the processes of histogenesis. Results: The studies show that in the postnatal period, the formation of the crown, externally covered with cuticular epithelium, marks the formation of the primordium of the permanent tooth at the follicle stage. After eruption of a tooth, different parts of its crown have three individual structural and functional barriers to enamel biomineralization. The first one is provided by the cuticular epithelium of the pitted areas of the crown, which ensures filtering of the salivary fluid from the protein deposit in the form of a pellicle. The second barrier is defined on the lateral and cuspidate surfaces of the enamel, where the cuticle is erased or poorly expressed. The third structural and functional barrier of enamel biomineralization is located in the cervical portion of teeth of different classes. Conclusions: Different areas of the enamel in the tooth crown have specific filtration barriers, which can be distinguished as follows: pit-and-fissure-and-groove, cuspidateand-approximal, and cervical barriers. The cuticle is poorly expressed or totally absent on the cusps of the tooth crowns in contrast to pitted areas.
The aim: Thepaper wasaimedat thestudyof thebiomineralization processesofa permanentdental crown in thepostnatal period of histogenesis. Materials and methods: The study involved 30 culled puppies aged 30-40 days. To study the histogenesis of the germs of the permanent tooth from the cuticular epithelium in the postnatal period microscopic, electron microscopic, immunohistochemical methods of study have been used. Results: The studies show that in the postnatal period, the maturation of the germ of a permanent tooth starts with the synthesis of cells of the cuticular epithelium of the organic stroma, capable of subsequent mineralization. Differentiation of the proameloblasts, located on the surface of the dental papillary mesenchyma, at the early stages of histogenesis, is strongly associated with the appearance of a specific protein taftelin. Origination of secretory ameloblasts, which produce the protein enamelin, triggers the process of secondary biomineralization of the enamel. The terminal processes of the secretory ameloblasts produce the protein in the form of layers that overlap each other at a certain angle. Such layering of the structures of enamel and dentin contributes to the S-shaped maturation of the hard tooth tissues, strengthening them considerably. At the follicle stage, maturation of the dental crown, coated with cuticular epithelium, occurs. Invaginations of the cuticular epithelium form a characteristic topography of the dental crown, and enamel projections are further formed by the ameloblasts. Epitheliocytes of the inner layer of the enamel organ have desmosomal connections that allow the filtration of the salivary fluid at the stage of the enamel trophism. Conclusions: The findings of the study suggest that, normally, due to the cuticular epithelium, filtration of the salivary fluid occurs with protein deposition on it and subsequent infiltration of the calcium salts into the subjacent enamel.
Relevance. The issue of quality endodontic treatment of teeth with complicated caries is still known as requiring thoughtful research. A significant percentage of periodontitis occurs in the area of furcations of multi-rooted teeth, sometimes alone, but more often as combined with apical periodontitis. Among the number of unsolved tasks, there is question about furcation areas and in particularly their antiseptic treatment and obturation in the complex treatment of chronic apical periodontitis of multi-rooted teeth. Aim: to investigate the histo-morphological features of the furcation area of the first, second molars of the upper and lower jaws and, according to the results of the experimental study, to develop a scheme of complex treatment of chronic apical periodontitis of multi-rooted teeth. Materials and methods. Ten first and second molars of both jaws not affected by fluorosis and removed according to orthodontic or surgical indications in patients aged from 25 to 50 years, were used for this study. In the first stage, transverse and longitudinal sections of the molars were made using diamond-coated separation disks. Using an orthopaedic tip, the first half of the molars were cut longitudinally in the mesio-distal direction with separation disks, under water cooling. The other half of the molars were cut transversely along the neck of the tooth and histochemically stained. In the second stage of the study, we used the experimental application of photodynamic therapy for antiseptic treatment of furcation channels and sealing them with citrate buffer. For this purpose, the next two first and two second mandibular molars were selected, respectively dissected in two planes. Samples were fixed in a vertical position; cotton rolls soaked with 2% methylene blue were placed onto the bottom of each half for 30 s., 1 min., 5 min., and 24 h. In this study we used light binocular stereoscopic microscope MBS-9; histochemical dyes: CHIC-thionine, ammonia silver solution "Argentat", reducing agent (hydroquinone), methylene blue, device "UFL - 122" company "Lux Dent", citrate buffer solution and white clay. The results were recorded with a digital camera mounted on a microscope tube. Results and discussion. The results of histochemical examination of ten molars showed the presence of furcation channels in four teeth. Two samples were stained with CHIC-thionine, the others were stained with two-component "Argenate". The selected samples were dissected in the sagittal plane through the area of localization of the furcation channels and studied under the microscope (magnification: 8x32). In teeth dissected in the transverse plane, the crown and mouth pulp were instrumentally removed without dilation of the root canals and stained accordingly. Thus, when modelling the stage of photodynamic treatment using a 2% solution of methylene blue, there is a significant filling of furcation channels and root canals along their entire length. The photosensitizer 2% methylene blue at the exposure of 30s demonstrates the highest efficiency at the minimum staining of surrounding fabrics. The microscopy was performed to confirm the ability of the photosensitizer to penetrate into the furcation channels at х8 – х32 magnification. After the experimental filling of furcation channels and root canals, we can see clear white stripes along their entire length on the dentin surface of the longitudinal section of the root; these stripes are obliquely directed towards the canal surface and consist of numerous dentinal tubules impregnated with citrate buffer. Numerous thin white lines are clearly visible on the surface of the section that run in parallel, tangentially through almost the entire thickness of the root wall and end up their course in the area around the peripulpal dentin. This indicates the formation of calcium citrate in the root canal that tightly covers its entire surface impregnating the dentinal tubules and completely fills them along their entire length. Therefore, the experimental model of using 2% methylene blue photosensitizer at a 30 s. exposure for photodynamic therapy and citrate buffer for obturating furcation and root canals can be applied in the treatment of patients with chronic apical periodontitis and lesions of the furcation area. Conclusions. Thus, morphological studies of the first and second molars of both jaws have shown the presence of furcation channels, which anatomical structure is quite complex and demanding in terms of their antiseptic treatment and filling. Therefore, we developed new effective for disinfection and obturation techniques including applying photodynamic therapy for disinfection of furcation channels and citrate buffer for their obturation.
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