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7. Khabilov N. L., Mun T. O., Usmonov F. K.//Rasmiy akhborotnoma. - 2013. - № 6. - P. 66-67.
8. Paraskevich V. A. Development of the system of dental implants for rehabilitation of patients with total absence of teeth//Dissertation work for doctor of medical sciences. - Moscow, 2008-219 p.
9. Bezrukov V. M., Matveeva A. I., Kulakov A. A. Results and prospects of research of problems of dental implantology in Russia//Sto-matology. - 2002. - No. 1. - P. 52-55.
Habilov Nigman Lukmanovich, Usmonov Farkhod Komilzhonovich, Mun Tatyana Olegovna, Tashkent State Dental Institute Milusheva Rakiya Yunusovna, Holmuminov Abdufatto Axatovich, Research Center for Polymer Chemistry and Physics at National University of Uzbekistan E-mail: farus2004@mail.ru
The problem of creating a bioactive layer of the intraosseous dental implants in Uzbekistan
Abstract: Calcium phosphate coatings on dental implants accelerate bone growth and enhance bone fixation. To increase the biocompatibility of the electrolytic coating is supposed to use bioactive natural polymer — Chitosan Bombyx mori, extracted from waste silk production in Uzbekistan. It is assumed that the inclusion of chitosan in electrodeposition coating tricalcium phosphate (CFP) will improve the biocompatibility of the coating, while retaining its original mechanical properties.
Keyword: dentistry, dental implants, bio-active layer, three-calcium phosphate coating, chitosan, bombyx mori, biocom-patibility, porosity, surface roughness of a bioactive layer.
Calcium phosphate coatings on dental or orthopedic implants accelerate the growth ofbone tissue and improve bone fixation [1]. Typically, these coatings promote bone ingrowth during the healing period of the first, leading to permanent fixation technique. Two types of calcium phosphate: hydroxyapatite and tricalcium phosphate are used as a coating material. Hydroxyapatite and tricalcium phosphate are the backbone of naturally occurring inorganic component ofbone. Tricalcium phosphate — a porous form of calcium phosphate. Tricalcium phosphate is used as a biological filler which is partly resorbed and replaced by bone. The transformation of tricalcium phosphate is a pivotal point of periodontal regeneration. This "scaffolding" for the formation of new bone, which is then replaced by newly formed bone. Since hydroxyapatite — is imported drug, however local product tricalcium phosphate was used in this study. The plasma spraying method mainly uses calcium phosphate coatings on metal sputtering [2]. However, this method is carried out at high temperatures, which may alter the structure of the coating of calcium phosphate (CFP).
An alternative method for the development of CFR at low temperatures is a method of electrodeposition. In addition, this method allows you to control the porosity and thickness of the coating [3]. To increase the biocompatibility of the electrolytic coating use of our bioactive natural polymer — Chitosan Bombyx mori, extracted from waste silk production in Uzbekistan is supposed. We believe that the inclusion of chitosan in electrodeposition CFP improves the biocompatibility of the coating, meantime it maintains its original mechanical properties.
Conventional methods of obtaining polysaccharide chitosan is characterized by chemical and structural heterogeneity since even after the harsh chemical processing conditions contains small amounts of protein and mineral impurities, and by a broad
molecular weight distribution. The latter causes the formation of insoluble gel particles by dissolving chitosan. These factors significantly limit its application field. For our studies highly purified chitosan was required, because its further use is associated with a medical application. For this purpose, cleaning chitosan Bombyx mori from the guild of chitosan, obtained on the basis of the Research Center for Polymer Chemistry and Physics at the National University of Uzbekistan (NUU.) was carried out. Chitosan is a guild grayish pulp particles of irregular shape, strongly contaminated extraneous mechanical impurities. Physico-chemical properties of the starting chitosan examined by elemental analysis, infrared spectroscopy (IR), X-ray analysis, the degree of deacety-lation (SDA), molecular weight (MW).
Plant chitosan was characterized by nitrogen content — 7.42 %, ash — 3.37 %, solubilityt — 86.05 %, humidityt — 13.68 %, crystall conditiont — degree of 41 % (Table 1). MM is defined viscomet-ric — 170 kDa; SDA determined Conductivity — 71.5 % (Fig. 1).
On the basis of this sample chitosan purification technique that was developed, which was pre-dissolved in 2 % chitosan in acetic acid, the precipitation and coagulation of the solution at a certain pH, alcohol washing, centrifugation and freeze-dried sample was conducted. Experimentally optimal concentrations of the chitosan solution were chosen, the ratio precipitant — chitosan solution, the coagulation time, pH. The obtained chitosan samples characterized by a high degree of purity: at the IR spectra no peak acetamido group related to chitin, amide II peak at 1590 cm-1 peak of greater intensity manifested. The nitrogen content and the solubility of the obtained samples is considerably increased and reaches 98, 8.52 and 8 %, respectively. Reduction of ash samples (1.43 %) is almost 2 times as evidenced by an increase in the purity of the sample (Table 1).
(NaOH),
a b
Fig. 1. a — the intrinsic viscosity of the shop chitosan in 0.3 M buffer SN3SOONa is 3.14 dl/g, MM = 170 kDa; b — SDA = 71.5 %
Table 1. - Test results chitosan Bombyx mori
№ Index Value
TSh 88.2-13:2011 Actual
Plant Purified
1. Appearance Loose weight without lumps or powder, with particles of irregular shape Loose weight with particles of irregular shape homogeneous powder
2. Color Cream, allowed yellowish grayish and brownish shades Cream Cream
3. Moisture conten t %, not more than 12 13.68 10.55
4. Ash content %, not more than 2 3.37 1.43
5. Particle size, mm. 10 10 0.2-0.6
6. Nitrogen content, % not less than 6.8 7.42 8.52
7. Solubility in 2 % acetic acid 85 86.05 98.85
8 pH 1 %, aqueous solution, not more than 8.5 7.5 7.5
9 Intrinsic viscosity, dl/g, not less than 1.64 3.14 2.5
IR spectroscopic analysis a lack of guild chitosan sample pu- On the X-ray diffraction patterns can be seen that a reduc-
rity chitosan manifestation peak acetamido group in the region tion in the degree of crystallinity of the samples up to 36-39 %,
was revealed as 1640 cm-1 and a weak peak intensity at 1550- which indicates an increase in amorphization of purified chitosan
1590 cm-1 (Figure 2). samples (Figure 3).
40 35 30 25 20 15 10
100 cm'1
Fig. 2. a — IR-spectrum of chitosan in the guild; b — IR-spectrum of purified chitosan
Fig. 3. Diffraction patterns: a — plant chitosan; b — purified chitosa
Fig. 4. a — purified HZ SN3SOONa buffer 0.3 M, the intrinsic viscosity of 2.48 dl/g, M.W. 130 kDa chitosan; b — SDA is 72 %
Fig. 4 shows the purified chitosan deacetylation degree, which is 72 %. The molecular weight of the purified chitosan ranges from 120 to 130 kDa.
Data on physical-chemical indicators of the guild and purified chitosan are shown in Table 1.
The purified chitosan was used for further coating with a titanium plate CFP. Laboratory equipment was assembled for coating,
which consists of a thermostated cell equipped with a temperature sensor, two electrodes: a reference electrode and a reference electrode and a cathode, which is attached to a titanium plate (Fig. 5).
Pre titanium plate of 30 mm. were prepared x 10 mm. x 1 mm., which are then processed to a certain roughness. The roughness of the plates was measured with an atomic force microscope brand Agilent Technologies 5500 (US). The data shown in Fig. 6.
Fig. 5. Scheme of laboratory setup for the electrolytic deposition of coatings on titanium plates
Fig. 6. AFM picture: a — the initial titanium plate, plate roughness 1.66 micron; b — the primary processing — plate roughness 2.58 um; c — the final treatment — roughness of the plate — 4.09 um
The tricalcium phosphate powder (Ca3 (PO4)2) was used as the calcium-containing coating. Tricalcium phosphate is a tertiary calcium phosphate, also known as bone ash. This phosphate is a rich source of calcium and phosphorus, which are available to form cells.
As used Ca3 (PO4) 2, the structural formula:
It represents a grayish powder with a molecular weight of 310.18 g/mol and a density of 2.81 g/cc, measured under standard conditions (25°C, 100 kPa).
Elemental analysis data are given in Table 2. This sample has a large ash content ~ 60 % of cells, poorly soluble in water but readily soluble in 2 % acetic acid to form phosphates. There have also been removed IR spectrum and the powder diffraction pattern of tricalcium phosphate (Fig. 7 a, b).
On Ca3 IR spectrum (PO4) 2 p resence ofphosphate anions confirmed broad strong absorption band with a maximum in the range of 1050 cm1 (doublet with the presence of shoulder 1130 cm1) belonging to the antisymmetric vibration phosphate anion and bending vibrations — (OPO) = 550 cm1.
Table 2. - Physico-chemical characteristics of Ca3 (PO4) 2
Sample Humidity, % Ash, % Solubility, %
H2 O 2 % CH3COOH
Ca3 (P04)2 1.68 58.40 43.68 96.01
a
b
c
Results of dental implantation at patients with the accompanying somatic pathology
Fig. 7. a — IR; b — diffraction pattern of Ca3 (PO4) 2
As seen from the diffractogram of the sample, the peak at 20 = 300 clearly describes tricalcium phosphate.
Preparation of calcium/phosphate chitosan coatings Ti plate (30 mm. x 10 mm. x 1 mm.) with a roughness of 4.0 microns were cleaned with acetone using ultrasonic, ethanol (96 %), and demineralized water. Electrolytically precipitated calcium phosphate coating was prepared on the Ti cathode plate at 52°C for 10 hours in a TCP (pH 7.0 buffer) supersaturated solution with a supported current 2.0 mA/cm2 galvanostatic installation. Using scanning electron microscopy (SEM) were recorded for
the coating formation TKF Ti plate with a coating thickness of 10 -14 microns.
For electrodeposited on a titanium plate chitosan purified chitosan solution was prepared with a concentration of 0.5 to 0.9 g/l by dissolving chitosan (72 % SDA) in 2 % acetic acid, which is then added to the supersaturated solution TKF. Deposition was done at 52°C for 15 hours in a supersaturated solution with chitosan TKF pH buffer (6.6 ~ 6.7), supported with a current of 2.0 mA/cm2. The plates were then washed with demineralized water and dried at 50°C for 12 hours.
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b
a
Yarmukhamedov Bekhzod, Associated professor, PhD, Tashkent state dental institute, Uzbekistan, Department of oral surgery and dental implantology E-mail: yabehzod@gmail.com
Results of dental implantation at patients with the accompanying somatic pathology
Abstract: Until recently operations of dental implantation were performed at patients of not having associated diseases. Now researches of opportunities of dental implantation at different types of the accompanying somatopathies are conducted. Keywords: dental implantation, somatic pathology, cardiovascular system, excretory system.
