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43
STOMATOLOGY
UDC 616.9
MORPHOLOGICAL CHANGES IN THE STATE OF DENTAL TISSUES IN THE TREATMENT OF DEEP CARIES WITH DENTIN-SEALING LIQUID AND LOW-INTENSITY LASER RADIATION (CLINICAL AND EXPERIMENTAL RESEARCH) M.S.Kovaleva, A.A.Britova
Yaroslav-the-Wise Novgorod State University, Alya.Britova@novsu.ru
The article shows the results of morphological studies of dental hard tissues after the application of methods of treatment of deep caries with dentin-sealing liquid and low-intensity laser therapy. This new method is preventive measure against repeated and recurrent caries.
Keywords: deep dentin fluoridation, deep caries, laser therapy, cuprum-calcium hydroxide, odonthoblasts
Статья отображает результаты морфологического исследования твердых тканей зуба после применения методики лечения глубокого кариеса зубов с использованием дентин-герметизирующей жидкости и низкоинтенсивного лазерного излучения. Этот новый метод является хорошей мерой по предотвращению развития вторичного и рецидивного кариеса. Ключевые слова: глубокое фторирование дентина, глубокий кариес, лазерное излучение, гидроокись меди-кальция, одонтобласты
Introduction
The problem of deep caries treating until now remains unsolved due to the fact that success of treatment for the disease is largely determined by the chosen method. Certanly age, specific and nonspecific protection factors of oral cavity, mineral metabolism have a huge influence on the treatment outcome. Therefore until now researches are carried out to find an alternative method of treatment of deep dental caries, which could guarantee a positive result, namely, the ability of dental pulp to product reparative dentin in a short time period.
Complications often appear after treatment as the pulp of the tooth is located in close proximity to the cavity. Method for deep fluoridation of dentin has been recently proposed; it includes using of dentin-sealing fluid with cocurrent using of different fluids [1]: fluoride, magnesium silicate hydroxide, copper, calcium and sodium fluoride as stabilizing agent. Highly dispersed cop-per-calcium hydroxide included in this compound has 100 times more powerful disinfecting effect than calcium hydroxide being a part of the therapeutic caps [2]. Substance containing copper (alkaline copper fluoride) tightly fills in the lumen of dentinal tubules during deep fluoridation and has permanent bactericidal action due to the small crystal size — 50 A, which is much smaller than the diameter of dentinal tubules [3]. Applied to the bottom and walls of the cavity preparation is capable to prevent secondary caries for decades [4].
When diagnosing caries special attention should be paid to the state of the dental pulp as the first reaction of the pulp is observed immediately after the spreading of caries process to enamel dentin [5]. Depending on this appropriate method of treatment is chosen: the application of calcium-containing pads (if intact
pulp and thick layer of dentin) on the bottom of the prepared cavity with pre-processing of cavity with mild antiseptic solution [6] or delayed fillings [9]. In the practice of preventive dentistry these methods were not always worth because in spite of direct effects on the focus of increased demineralization the tooth pulp was not subjected to indirect effects and proceeding from the general principles of physiology the pathological focus which in this case is focus of demineralization needed combined treatment.
To activate the process of dentin mineralization method of deep fluoridation [7] and physical factors such as low-intensity laser radiation [10] are used.
In medical practice, including dentistry, laser technique [11] has found extensive use. Anticarious action of pulsed laser light is composed of several components: a direct effect on dental hard tissue leading to a change in the permeability of the enamel, increased microhardness and remineralization; indirect effects through the tooth pulp, which is manifested by stimulation of microcirculation and metabolism, increased activity of odontoblasts to form dentin replacement. In addition to direct local effect laser radiation has a general effect, reflected in the stimulation of the immune defense mechanisms, neurohumoral and other systems leading to a general mobilization of the adaptive reaction of the body, improving its homeostasis [12].
Based on the foregoing we propose a new method [13] of treatment of deep dental caries (patent number 2,286,816) in order to improve the effectiveness of treatment [14]. To confirm the effectiveness of techniques morphological study of the teeth was conducted before the treatment and after the application of the above method of treatment of deep dental caries in control terms.
Materials and methods
40 patients aged 18 to 45 years with deep caries have been treated. 63 teeth including 41 molars, 22 premolars have been cured. All patients were examined with the use of main and additional methods before the intervention, during treatment and in control terms of 14 days and 9 months later. Throughout the study period electro-exitability threshold of tooth pulp (electric pulp test — EPT) was determined, radiography was performed in 9 months.
Dentin-sealing fluid of Human Hemi company (Germany) consisting of two different composition of fluids has been used for the treatment. Fluid #2 is a suspension of copper-calcium hydroxide, fluid #1 — fluoride magnesium silicate, copper sulfate II, sodium fluoride as stabilizing agent and distilled water. As a permanent seal photopolymer with the adhesive system Filtek Z250 (6 generations) has been used. The effect of low-intensity laser irradiation (LILI) was carried out step by step; fluid #2 was exposed within 15 seconds, then the mixture of fluids ##1 and 2 — within 30 seconds. Cavitary therapy apparatus (CTA) «Ulybka 01» generating a continuous laser radiation with a wavelength of 0.64 microns at a power output of 15 mW (Fig.1) has been used.
Fig.1. Cavitary therapy apparatus «Ulybka 01»
The experimental work was performed on 20 rats of Wistar line weighing 200.0 — 220.0, and 2 mongrel dogs weighing 15.0 and 10.0 kg. Studies have been carried out in accordance with the European Convention for the Protection of Vertebrate Animals used for experimental and other scientific purposes (ETS № 123). All interventions on rats have been performed under chloroform anesthesia, on dogs — under general anesthesia using «Zoletil» and «Ksila» drugs.
Animals were divided into two groups; 1st group of animals — the usual method of treatment, 2nd group of animals — treatment with dentin-sealing liquid and low-intensity laser radiation. The hard tissue of teeth was used for morphological study. The study was conducted at the level of light microscopy. Tissues of extracted teeth were fixed in solution of 10% neutral formalin. Decalcification was carried out by drug «Bio-dek» (BioVitrum). Dehydration in alcohols and filling with paraffin-celloid mixture were performed. Slice of preparation of thickness 6.5 microns were stained according to Van Gieson.
Results and discussion
None of the patients has noted the appearance of post-sealing pain immediately after treatment. None has complained in the control terms of observation. EPT data before treatment on average were 8.5 ± 0.09 mA, in 14 days — 7.0, in 28 days — 6.0. 2 months later 16 people were examined, the numbers were 5.0 mA, in 9 months numbers of five surveyed equaled 4.0 mA. Also secondary or recurrent caries have not been mentioned. After 12 months in 20 patients who came to re-examination, positive results persisted. All the seals were satisfactory; color-stable, marginal adaptation without failure.
The proposed method has improved the results of treatment of deep caries due to mineralization of dental hard tissues. Exposure to LILI was determined empirically with following microcrystallography. (Fig.2). For the chosen exposure effects of LILI form more structured, well-defined, large crystals of the dentin-sealing liquid that is necessary for deeper penetration of liquid in treatment of patients with deep caries.
Fig.2. Crystals of dentin-sealing liquid have pronounced pore planes, well-defined, exposition of LILI - 45 seconds
Comparative analysis of histological preparations with the traditional treatment and with dentin-sealing liquid and low-intensity laser radiation allowed noting that the height of odontoblasts and the bulk density of cells in this layer in the second group of animals increased. Thus, in the 1st group of Wistar rats (Fig.3) odontoblasts represented thin layer of flat cells; then in the 2nd group of animals (Fig.4) the cells were mainly cubic or cylindrical shape. Increase of bulk density of odontoblastic layer was registered in the 2nd group of animals. Increase of fibroblastic cells is marked in the pulp. The foregoing suggests increase in functional activity of odontoblasts and the stimulating effect of used method. A similar picture is observed in dogs. In preparations of the 1st group of animals (Fig.5) odontoblasts represent one cell layer, while preparation of the 2nd group has visually remarkable increase in bulk density of odontoblasts represented by cylindrical cells. Remarkable increase of fibroblastic cells (Fig.6) is also noted; undifferentiated cells are revealed. Among the fibers of loose connective tissue the capillaries can be seen, the total volume and the density of which prevail in comparison with the 1st group.
Fig.3. Dental tissues of animals (rats) of the 1s group. Stained according to Van Gieson. *400. Flat odontoblasts (marked by single arrow), areas of tissue rarefaction around odontoblasts. Light cell nuclei of pulp, heterochromatin located on the periphery
Fig.6. Increase of the cellular content of odontoblasts. Elongated shape of odontoblasts. Increased content of microvasculature cells and increase of bulk density of loose connective tissue of pulp
Fig.4. Dental tissues of animals (rats) of the 2nd group. Remarkable increase of odontoblasts, cubic and cylindrical cells along with flat ones. Increase of bulk density of odontoblastic layer
Fig.5. Dental tissues of animals (dogs) of the 1st group. Stained according to Van Gieson. *400. Odontoblasts marked with arrow. Single layer of odontoblasts. Compact arrangement with prevalance of fibrous components of the pulp
In order to determine the general picture of the observed phenomena morphometric study was used by imposing grid with equidistant points for microscopic stereometric research of organs and the electronic images [8]. The results of the calculation show the proportion of the nuclei of endothelial cells in the dental pulp of the tested animals in the control and experimental groups. Histograms show percentage increase of nuclear structures of endothelial cells of the pulp in experimental samples compared with control ones (Fig.7, 8).
Fig.7. Changes of the number of nuclei of endothelial cells of the pulp in the samples of teeth of rats
Fig. 8. Changes of the number of nuclei of endothelial cells of the pulp in the samples of teeth of dogs.
Increasing of endothelial cells in the pulp of teeth of experimental animals testifies the phenomenf of an-giogenesis and improvement of microcirculation of tissue.
Conclusions
1. To confirm the efficacy of the proposed method histological analysis and morphometric study of cellular structures of studied tissues should be carried on.
2. Data of morphometric studies indicate phenomena of neogenesis and increasing of vessels of microcir-culatory bloodstream against the background of the applied treatment.
3. Morphological analysis of dental tissues in experimental animals and clinical picture of patients' teeth after treatment by proposed method show that the applied method of treatment is effective.
4. Treatment of deep caries with dentin-sealing liquid and low-intensity laser radiation can be considered as alternative in comparison with previously proposed methods of treatment of deep caries.
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