Investigation of functional activity human dental pulp stem cells at acute and chronic pulpitis.

UNLABELLED: It is already recognized that together with the other connective tissues organ-specific progenic stem cells are also found in postnatal dental pulp. This group of undifferentiated cells is only 1% of total cell population of the pulp. The aim of the study was the identification of stem cells in human dental pulp, detection of their localization and assessment of functional activity during inflammation process and/or at norm. The obtained results showed that at acute pulpitis the pulp stroma is hypocellular in comparison with the norm but cells proliferative activity is low. CD 133 and NCAM (CD 56) positive stem cells were found in perivascularl space of the pulp stroma and in Hohle layer. At process prolongation and transition to the chronic phase pulp stroma is hypercellular, the cells with large, rounded or oval-shaped nuclei with clear chromatin appear together with fibroblasts. They are distributed as about entire thickness of the stroma as especially Hohle layer. In such cells higher proliferative activity (Ki67 expression) was observed. The cells in the mentioned proliferation phase are intensively marked by CD133, the rate of which is high in Hohle layer and along it. A large number of NCAM (CD 56) positive cells appear in pulp stroma. CONCLUSIONS: During pulpitis an involvement of stem cells into the process of reparative dentinogenesis should be conducted stepwise. In acute cases of the disease, stem cell perivascularl mobilization and proliferation and its migration to Hohle layer occur in response to irritation /stimulation. Chronification of the process leads not only to the migration of stem cells to the periphery of the pulp but also s their В«maturationВ¼ (increase of NCAM expression in the stem cells), which causes an increase the number of dentin producing active odontoblasts and initiation of reparative dentinogenesis.

Isolation of dentin tissue by usinga new liner biodentine at management of simulated experimental caries.

The aim of our study was the use of different types of isolation systems in the treatment of experimentally simulated dental caries that will allow to present additional comparative characteristic for morphological responses of the pulp.For realization of this purpose, 3 systems have been selected: UltraBlend (Ultradent), Biodentine (Septodont) and adhesive system Prime&Bond NT (Dentsply). The study was conducted at the laboratory of Alexander Natishvili Institute of Morphology. For this experiment, 12 male, 6 months of age rabbits were selected. There were created 3 experimental groups, each of which included 4 rabbits. Restoration of the teeth in experimental rabbits with Biodentine revealed sufficient physical properties enabling the operator most comfortably conduct his/her clinical activities: kneading, bringing into caries cavity, condensing and filling dental defect. Isolation of dentin by Biodentine doesn't contradict and/or reduce application of adhesive systems, which is also important for teeth restorations. Biodentine has optimal working time (final curing 10-12 minutes) enabling the operator to conduct maximal formation of material at the bottom of caries cavity.

Clinical parallels in treatment of reversible pulpitis.

Current study is aiming at comparative characterization of clinical aspects of preparations, containing calcium hydroxide, in the treatment of pulp hyperemia (primary pulpitis). With this aim two products, made on the base of calcium hydroxide, were selected: Ultra-Blend (Ultradent) and Life (Kerr). The results obtained after application of these materials were compared with the results obtained in patients affected with the similar pathology, where Ca(OH)2 containing liners were not used in treatment process. 54 teeth were selected for the study, among them - 38 molars and 16 premolars. Patients were divided into three groups: I group (21 teeth) included the patients who underwent pulp hyperemia treatment with Life, II group - patients treated with Ultra-Blend (19 teeth) and III group - patients without any pulp protections respectively (13 teeth). It was decided to perform treatment assessment and making appropriate conclusions according to two factors: degree of adhesion of restorations to teeth surfaces and teeth post-restorative sensitivity. Comparison of the obtained data of study and control groups revealed weakening of adhesion between filling and tooth tissues practically in all 3groups, however, with different rate and intensity: in I group on radioography micro cracks were revealed in 10 cases (47.6%), II group -7 (36.5%) cases and treating group - 4 (30.7%) cases, respectively. The obtained results of the current study revealed non-homogenous picture: in I group where Kerr liner was applied - hypersensitivity was revealed in 12 (57.1%) cases, II group - 6 (31.5%) and III group - 7 (53.8%) cases. It is concluded that the primary reason for teeth prolonged and enhanced sensitivity is a micro-percolation factor into the perimeter. But if we admit the application of medical liners in the treatment of pulp hyperemia, doctor's choice should be made on those, providing maximum prevention of further complications. At this stage of the study such features were better revealed by Ultra-Blend. However, the final clinical outcomes - pulp hyperemia disappearance, no complains, production of tertiary dentin and so on - might be expected within a year after the end of the treatment. Currently, it will be interesting to study the pulp chamber condition, evaluation of electrophysiological parameters of the tooth and restoration quality. The mentioned issues will be studied in the future studies.

[Theoretical and practical principles of dentinogenesis: hypotheses and confirmed clinically reality].

The problem of maintaining dental vitality and stimulating reparative processes is a priority in modern odontology. Restorative processes depend not only on the type and size of tissue damage, but also on the protection capacity and integrity of the structural/functional pulp-dentin boundary. Primary dentin that is initiated in the intrauterine period has unique structure and composition. Secondary dentin continues to form after the tooth is erupted, then after root formation is finished, and throughout life. Actually the primary and secondary dentins have similar tissue structures developed at different stages of dentinogenesis. Primary dentinogenesis is initiated by odontoblasts located in the periphery of dental pulp. Secondary dentin as a structure already exists once root formation is complete, but at that stage is has low levels of mineralization. Formation of tertiary dentin is always reactionary to different pathologies and is initiated by so called "transitional odontoblasts" (odontoblast-like cells) and partially fibroblasts. Odontotropic and anti-inflammatory medications strongly change structural characteristics of the dentin. Pulpal ability to produce dentin-like matrix (tertiary dentin) is an important component of the pulp-dentin reparative capacity. Only specific characteristics of the dentin can account for indications and contraindications for using restorative liners and explain the impact of adhesive systems on these. In this context, the interest is high to the dentin and its response and change in reaction to different stimuli. Dental caries and other pathological processes (abrasion, erosion, attrition) seriously affect dentin vital activity causing it to change to the "emergency" mode. This process is viewed not as resulting from pulp medication but as reactionary, aimed for self-preservation. In such cases the major focus is not on drug composition but on pulpal response. The pulp may be said to "form tertiary dentin for self-protection". In conclusion, the tertiary dentin that forms as a result of pathological processes (express-dentin, reparatory dentin) could be identified as a perfect barrier for the pulp necessary for keeping it vital. And investigation of mechanisms causing primary stimulation of odontoblasts and triggering the reparative processes remains a pressing problem in modern odontology.