• Journal of Periodontal and Implant Science
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• v.36 no.1
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• pp.195-210
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• 2006

The aim of this study is to evaluate the effects of combination of rhBMP-4 and chitosan, which have osteoinductive capacity, on the regeneration of bone defects in dogs. Three beagle dogs aged over one and half years and weighed about 15Kg were used in this study. Three round defects were made by trephine bur in each side of mandibles. Each defect was filled with collagen, chitosan, rhBMP-4/chitosan. The dogs were sacrificed at 1, 3 or 8 weeks postsurgery and the results were evaluated histologically. The results of this study were as follows: 1. The sign of new bone formation, rearrangement of osteoblasts was revealed adjacent of preexisted bone or around graft materials such as chitosan. 2. The descending order of groups in bone regeneration speed was the rhBMP-4/chitosan group, chitosan group, collagen group. In the combination group, new bone was regenerated more and in better quality than others. 3. The regeneration of bone was observed in the rhBMP-4/chitosan group in 3 weeks after surgery. In 8 weeks after surgery, bone regeneration was observed in all three groups, and new bone at 8th week was denser in the chitosan and rhBMP-4/chitosan group than collagen group. In conclusion, rhBMP-4 and chitosan can be applied in the bone regeneration procedures usefully. It is considered that chitosan can be a splint for the maintenance of the defect form and produce much better effect when used with good grafting material or bone morphogenetic protein.

• The korean journal of orthodontics
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• v.39 no.5
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• pp.278-288
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• 2009

Objective: The aim of this study was to investigate the changes in the center of resistance of the maxillary teeth in relation to alveolar bone loss. Methods: A finite element model, which included the upper dentition and periodontal ligament, was designed according to the amount of bone loss (0 mm, 2 mm, 4 mm). The teeth in each group were fixed with buccal and lingual arch wires and splint wires. Retraction and intrusion forces of 200 g for 4 and 6 anterior teeth groups and 400 g for the full dentition group were applied. Results: The centers of resistance were at 13.5 mm, 14.5 mm, 15 mm apical and 12 mm, 12 mm, 12.5 mm posterior in the 4 incisor group; 13.5 mm, 14.5 mm, 15 mm apical and 14 mm, 14 mm, 14.5 mm posterior in the 6 anterior teeth group; and 11 mm, 13 mm, 14.5 mm apical and 26.5 mm, 27 mm, 25.5 mm posterior in the full dentition group respectively according to 0 mm, 2 mm, 4 mm bone loss. Conclusions: The center of resistance shifted apically and posteriorly as alveolar bone loss increased in 4 and 6 anterior teeth groups. However, in the full dentition group, the center of resistance shifted apically and anteriorly in the 4 mm bone loss model.

• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.2
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• pp.116-126
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• 2018

Purpose: The purpose of this study was to analyze the factors affecting the survival rate and the marginal bone level of dental implants that have functioned over 7-years. Materials and Methods: In 92 patients, 178 dental implants were included. Implant-related factors (diameter, length, prosthetic splint), patient-related factors (gender, smoking, plaque index, compliance to supportive periodontal therapy) and surgery-related factors (proficiency of surgeon, bone graft) were evaluated via clinical and radiographic examination. The marginal bone level was determined by intraoral standard radiography at the mesial and distal aspects of each implant using an image analysis software program. Results: The survival rate of all the implants was 94.94% and the marginal bone level was $0.89{\pm}1.05mm$, these results are consistent with other studies that present long-term good clinical results. Implant length and plaque index among several factors were statistically significant for implant survival rate (P < 0.05). Smoking and the presence of regeneration surgery were statistically significant for the marginal bone level (P < 0.05). Conclusion: Dental implant that have functioned over 7-years showed favorable long-term survival rates and marginal bone level. Implant length and plaque control should be considered for improving the long-term clinical results. It is needed that careful application of bone regeneration technique and smoking control for maintaining of marginal bone level.