| OBJECTIVE:1.A new desensitizing gel was prepared through a confirmed prescription of bamboo salt, Calcined oyster, Drynaria fortunei, Indigo naturalis, Rehmannia glutinosa, Neotame and Poloxamer 407 (P407). The best concentration of P407 in prescription was selected according to the gelation temperature of gel.2.The effect of the desensitizing gel on dentinal tubule occlusion was investigated, compared to mouthwash slobber and Duraphat to study the mechanism.METHODS:1.A new desensitizing gel was prepared through a confirmed prescription of bamboo salt, Calcined oyster, Drynaria fortunei, Indigo naturalis, Rehmannia glutinosa, Neotame and Poloxamer 407 (P407). The best concentration of P407 in prescription was selected according to the gelation temperature of gel.Ethanol extracts of Drynaria fortunei, Indigo naturalis and Rehmannia glutinosa and hydrochloric acid extract of Calcined oyster were combined and concentrated to achieve the medicine liquid. Then bamboo salt and Sweetener Neotame were added into the medicine liquid to achieve the desensitizing solution. P407 were then slowly added to the solution got from the last step to prepare the desensitizing gel. The gelation temperature was measured by a test tube tilting method (TTM). A glass tube containing the desensitizing gel was placed in a low-temperature thermostat water bath. The temperature was increased. Through visual inspection, if the desensitizing gel started flowing when tilting the tube, the temperature displayed on the thermometer was determined as a gelation temperature. The best concentration of P407 in prescription was selected according to the gelation temperature of gel.2.The effect of the desensitizing gel on dentinal tubule occlusion was investigated, compared to mouthwash slobber and Duraphat to study the mechanism.Scanning electron microscopy (SEM) was used to assess effect of the desensitizing gel on dentinal tubule occlusion. 32 caries-free human premolars extracted from orthodontic patients were collected. All soft tissue deposits and calculus were removed from the teeth. All the teeth were sectioned horizontally at 1mm above the cemento-enamel junction. The cervical regions were cut into about 2-mm-thick dentin disks. These disks were wet ground tangentially to expose the dentin surface. The teeth were randomly divided into four groups according to the agents (tests and controls) used:a. Physiological saline group (blank control); b. Mouthwash slobber group (test); c. Duraphat group (positive control); d. Desensitizing gel group (test). The experimental agents were respectively applied onto corresponding groups. This procedure was repeated in every 8 hours for a month. After all the treatment, the specimens were fractured carefully on the middle. Half of the slices were positioned in a way that then could be observed in a cross-sectional view, while the others were positioned to permit a longitudinal view. These specimens were observed under an SEM.RESULTS:1.The results of gelation temperature measurements showed that the concentration formulations of P407 in desirable gelation temperature range were 0.27-0.30g/ml (gelation temperature 38-42℃). Thus, the gel will be a gel form in oral cavity and turn to liquid phase when gargling with warm water above the temperature of oral cavity. Finally, formulation containing 0.30g/ml of P407 was selected.2.The analysis of cross-sectional and longitudinal specimens under SEM indicated that after treatment with desensitizing gel, most of the tubules were occluded and the dentin surface was covered by sedimentation. Duraphat group and desensitizing gel group showed similar effects on occlusion of the dentinal tubules, much better than the effect of mouthwash slobber group and control group.CONCLUSION:Based on the findings of SEM Observation, the desensitizing gel exhibits an obvious effect on dentinal tubule occlusion, reducing the permeability of dentin in isolated teeth. It provides evidence for the desensitizing gel in managing DH. |
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