• Journal of Periodontal and Implant Science
• /
• v.27 no.2
• /
• pp.379-394
• /
• 1997

Several methods have been used for regeneration of tissue lost by periodontal disease. Subepithelial connective tissue graft technique, one of the technniques of mucogingival surgery, is used for the regeneration in esthetic problems such as recession, and denuded root coverage. This study is performed to evaluate the healing process and the regeneration and reattachment of periodontal tissue, including the reconstruction of junctional epithelium, and connective tissue. Alveolar defects in five adult dogs were treated with periodontal surgery and were attained by removing the marginal alveolar bone by $4{\time}3mm$ from CEJ in the labial side of incisors, and root surfaces were planed. The experimental sites were divided into two groups as follows. 1. root planing alone(control group) 2. with connective tissue graft (Experimental Group) In the two groups flaps were positioned and sutured tightly, the healing processes were observed and were histologically compared with each other after 2days, 4days, 1week, 2weeks, 4weeks. The results were obtained as follows : 1. In the two groups blood clots were observed as early as 2 and 4 days, and were resorbed at 1 week. 2. In the two groups moderate inflammation was observed as early as 2 and 4 days, decreased at 1 and 2 weeks, and disappeared at 4 weeks. 3. Junctional Epithelium migration was more significant in the control group, and was restrained by graft materials in the experimental group. 4. Features of connective tissue fiber attachment partially showed the parallel pattern in the two groups from 2 weeks, and entirely from 4weeks. 5. Anastomosis, between graft and connective tissue, appeared from 4 days in the experimental group and the border between them was not discriminated at 4weeks.

• Restorative Dentistry and Endodontics
• /
• v.32 no.1
• /
• pp.47-60
• /
• 2007

The purpose of this study is to compare and to evaluate the effect of pH and lactic acid concentration on the progression of artificial root caries lesion using polarizing microscope, and to evaluate the morphological changes of hydroxyapatite crystals of the demineralized area and to investigate the process of demineralization using scanning electron microscope. Artificial root caries lesion was created by dividing specimens into 3 pH groups (pH 4.3, 5.0, 5.5), and each pH group was divided into 3 lactic acid concentration groups (25 mM, 50 mM, 100 mM). Each group was immersed in acid buffer solution for 5 days and examined. The results were as follows : 1. Under polarized microscope, the depth of lesion was more effected by the lactic acid concentration rather than the pH. 2. Under scanning electron microscope, dissolution of hydroxyapatite crystals were increased as the lactic acid concentration increased and the pH decreased. 3. Demineralized hydroxyapatite crystals showed peripheral dissolution and decreased size and number within cluster of hydroxyapatite crystals and widening of intercluster and intercrystal spaces as the pH decreased and the lactic acid concentration increased. 4. Under scanning electron microscope evaluation of the surface zone, clusters of hydroxyapatite crystals were dissolved, and dissolution and reattachment of crystals on the surface of collagen fibrils were observed as the lactic acid concentration increased. 5. Under scanning electron microscope, demineralizatlon of dentin occurred not only independently but also with remineralization simultaneously. In conclusion, the study showed that pH and lactic acid concentration influenced the rate of progression of the lesion in artificial root caries. Demineralization process was progressed from the surface of the cluster of hydroxyapatite crystals and the morphology of hydroxyapatite crystals changed from round or elliptical shape into irregular shape as time elapsed.