The Preparation Of Periodontal Sustained-released Gel Of Galla Chinensis And Its Research In Vitro

Periodontitis is a multi-factor disease.There is no ideal treatment to cure it at present. Dental plaque is the initiation factor of periodontitis, but the destruction caused by bacteria is limited. A series of local and systemic reactions triggered by bacteria is the main reason for the destruction of periodontal tissues. The loss of periodontal attachment caused by periodontitis has been a very difficult problem that we have to face in clinical treatment.Medicine treatmeat, as an indispensable means of periodontal treatments, is often used to enhance and consolidate the effect after scaling. The periodontal local release agent can act directly on lesions, and maintain effective drug concentration for a long time. As a result, it has become the main agent in periodontal treatments. However, sustained-release agents used in clinic still have many deficiencies. No one has reached the ideal standard. So it is difficult to meet the clinical requirements.Natural medicine has become the focus of researchs in this realm. Galla chinensis has antibacterial, hemostatic, and other convergence effect. Research has shown that it can effectively inhibit the activity of various suspected periodontal bacteria, avoid HPDLFs from the destruction caused by LPS, promote the generation of HPDLFs and its attachment on cementum. It also can prevent the degradation of collagen through the inhibition of collagenase activity. Poly lactic and glycollic acid (PLGA) is a biodegradable polymer controlled release carrier. The efficient drug which is mixed in the material will release slowly with the gradual degradation of PLGA in the body, so it can achieve the purpose of continuous action.In this study, we will use Galla chinensis combined with PLGA to develop a periodontal sustained-release gel that its physical and chemical properties can be consistent with the clinical needs. The feasibility of the gel using in periodontal treatment will be discussed through the study on its effects on the multiplication, the activities of ALP and the expression of MMP-3 in HPDLFs. This study comprised four tests:1. The preliminary determination of the matrix ratio of the periodontal sustained-released gel of Galla chinensis and in vitro release studyDifferent concentrations of PLGA and different ratio of solvent were made into periodontal sustained-released gel of Galla chinensis, and its dissolution, setting time and the physical and chemical properties were observed.At the same time,we measured in vitro release study of various factors on the gel in vitro release of drugs. The results showed that: a mixed solvent 1MP more, PLGA dissolved sooner. The more the content of GTA, prepared by the gel mobility of the poorer, gel condensation water longer .And in the same proportion of mixed solvents, the PLGA density is higher ,the gel which makes more mounts thickly, meets the water set time to be also shorter.Gel in vitro release test results showed that the drug release ratio and the ratio of mixed solvents is proportional to 1MP, and is inversely proportional to the proportion of GTA and the density of PLGA.Simultaneously the higer the drug concentration , the higher rates of early release. All agents accumulated 7d release rate exceeded 80%. Integrated the various factors, we tentatively choose 1MP: GTA = 7:3, PLGA concentration of 40%, 8% Galla chinensis concentration of slow-release gel as a ratio of the reference value.2. Screening of the periodontal sustained-released gel formulation of Galla chinensis and quality inspectionWe made an orthogonal design at 3 levels of 3 factors (concentration of PLGA, portion of solvent and concentration of Galla chinensis) to measure the concentration of Galla chinensis in vitro, and used the releasing rate on the sixth day as a parameter. By calculating the range in order to explore a best formula of periodontal sustained-released gel of Galla chinensis, and inspect the quality of gel.The results indicated that: according to the range, the order of three factors' influence to the gel is PLGA concentration > solvent portion > Galla chinensis concentration. The best formula is : the concentration of PLGA = 35% (w /w) , 1MP:GTA = 7:3 and Galla chinensis's concentration = 4 % (w /w).The quality of study results showed the homogeneous gel, fine , have a certain viscosity and good stability.3. Effects of a periodontal sustained-released gel of Galla chinensis on the multiplication and the activities of ALP in HPDLFs inhibited by LPSWe used the cell culture technique, MTT and enzyme kinetics methods to investigate the effects of a periodontal sustained-released gel of Galla chinensis on the multiplication and the activities of ALP of human periodontal ligament fibroblasts(HPDLFs) induced by lipopolysaccharide(LPS).The results indicated that at the concentration of 100μg/mL,LPS could inhibit the multiplication of HPDLFs and the activities of ALP.Compared with the LPS group, the multiplication of HPDLFs and the activities of ALP of all the groups increased after treated with Galla chinensis solutions released from the gel. The most obvious effect could be observed among all the groups.The results suggest that the periodontal sustained- released gel of Galla chinensis can be an effective antagonist of the inhibitory effect of LPS on the HPDLFs.4. Effects of a periodontal sustained-released gel of Galla chinensis on the secretion of MMP-3 in human periodontal ligament fibroblasts induced by lipopolysaccharideIn this experiment HPDLFs were cultured in vitro and treated with LPS or with LPS + Galla chinensis solutions released from the gel at different time points. The amounts of MMP-3 secreted by HPDLFs were detected by ELISA. The results indicated that significant increases (P <0.05) in MMP-3 level were observed in the groups treated by LPS of the concentration from 50 to 100μg/ml when they were compared with blank group. After treated with Galla chinensis solutions released from the gel, the amounts of MMP-3 of all the groups were significantly lower than that of the LPS group (P<0.05). Significant differences were found among all the groups, the amount of MMP-3 secretion of HPDLFs treated with the solution released from the gel in the first 2 hours was the lowest. Compared with the LPS group, the inhibition ratio of MMP-3 of this solution was 75.77%. But with the extending of releasing time, the inhibitory action was weakening gradually, however, the inhibition ratio still remained as high as 32.26% on the 7th day. These results indicated that the periodontal sustained- released gel of Galla chinensis can significantly inhibit the secretion of MMP-3 in human periodontal ligament fibroblasts induced by LPS, and the inhibitory action can last 7 days.