• The korean journal of orthodontics
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• v.28 no.4 s.69
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• pp.591-600
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• 1998

The purpose of this study was to investigate the root resolution and repair pattern of human teeth according to the force magnitude, direction and duration during the initial leveling and alignment phase. 40gms to 500gms of force applied to the 37 experimental teeth with duration of 3 weeks to 7 months. Then, the experimental teeth were extracted. 13 control teeth were extracted without treatment. The results are as follows: 1. $59.5\%$ of 37 teeth exhibited root resorption. The initial resorption site was visible at the apex within 3 weeks with 100 gms samples, and the initial repair site was visible at the apex within 3 months with 400 gms samples. 2. Number of resorbed teeth increased with the duration of the force. 3. The depth of the resorption increased with the magnitude of the force. 4. The areas of resorbed root corresponded with the loading pattern. 5. The areas of resorbed root were highly correlated with the magnitude of the force. The result of this study suggest that root resorption could occur during the initial leveling and alignment phase, These initial injuries are all small and insignificant. It is the extensive type of apical root resolution that must be regarded as deleterious to the function and stability of the tooth moved. During the initial leveling and alignment phase lighter force of the interrupted type and short treatment period would be favorable with regard to avoidance of root resorption and repair of resorbed root surface.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.3
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• pp.490-497
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• 2007

Odontoma is defined as a benign odontogenic tumor containing enamel, dentin as well as cementum and constitued 22% of all odontogenic tumors. Although the lesions are commonly asymptomatic, they may be discovered routine radiographic examination. Odontomas often cause disturbances in the eruption of teeth such as, impaction or delayed eruption, retention of primary teeth, or abnomalities in the position of the teeth such as tipping or displacement of adjacent teeth. Radiologically, odontomas manifest as a dense radiopaque lesion surrounded by a thin radiotransparent halo. However, in some cases, radiopacity was not quite clear and images of the teeth shadowed very tiny odontomas. And at early development stages of odontoma, calcification remains immature and is difficult to diagnose on radiographs. This suggests that when delayed eruption of the teeth is found, periapical radiographs should be taken to clarify whether any small area of radiopaque material exists. This case report shows tiny odontomas involving an impacted tooth and crowding and we remove the tiny odontoma surgically.

• The korean journal of orthodontics
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• v.35 no.6 s.113
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• pp.451-458
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• 2005

Cephalometric superimposition is unable to evaluate tooth movement along the occlusal plane and the errors of photographing and superimposition of the occlusogram is also inevitable. The purpose of the present study was to evaluate the rotational movements of the maxillary posterior teeth following space closure after extraction of maxillary first premolars. using 3D dental images. In 19 adult females. analysis of rotational movements of the maxillary posterior teeth was performed between the initial and final 3D dental images superimposed on the maxillary hard palate. The results showed a diversity of rotational movements of posterior teeth. The causes of various rotational movements may be different rotation of molars in each case at the beginning of treatment. individual characters of the dental arch and tooth morphology. The results of the study indicate that accurate evaluation of rotational movements of posterior teeth following space closure after extraction of premolars using 3D dental images can be obtained through the subdivision of tooth movement during the initial aligning, space closure and finishing stages.

• Journal of Periodontal and Implant Science
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• v.23 no.3
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• pp.535-563
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• 1993

New techniques for regenerating the destructed periodontal tissue have been studied for many years. Current acceptable methods of promoting periodontal regeneration alre basis of removal of diseased soft tissue, root treatment, guided tissue regeneration, graft materials, biological mediators. Platelet-derived growth factor (PDGF) is one of polypeptide growth factor. PDGF have been reported as a biological mediator which regulate activities of wound healing progress including cell proliferation, migration, and metabolism. The purposes of this study is to evaluate the possibility of using the PDGF as a regeneration promoting agent for furcation involvement defect. Eight adult mongrel dogs were used in this experiment. The dogs were anesthetized with Pentobarbital Sodium (25-30 mg/kg of body weight, Tokyo chemical Co., Japan) and conventional periodontal prophylaxis were performed with ultrasonic scaler. With intrasulcular and crestal incision, mucoperiosteal flap was elevated. Following decortication with 1/2 high speed round bur, degree III furcation defect was made on mandibular second(P2) and fourth(P4) premolar. For the basic treatment of root surface, fully saturated citric acid was applied on the exposed root surface for 3 minutes. On the right P4 20ug of human recombinant PDGF-BB dissolved in acetic acid was applied with polypropylene autopipette. On the left P2 and right P2 PDGF-BB was applied after insertion of ${\beta}-Tricalcium$ phosphate(TCP) and collagen (Collatape) respectively. Left mandibular P4 was used as control. Systemic antibiotics (Penicillin-G benzathine and penicillin-G procaine, 1 ml per 10-25 1bs body weight) were administrated intramuscular for 2 weeks after surgery. Irrigation with 0.1% Chlorhexidine Gluconate around operated sites was performed during the whole experimental period except one day immediate after surgery. Soft diets were fed through the whole experiment period. After 2, 4, 8, 12 weeks, the animals were sacrificed by perfusion technique. Tissue block was excised including the tooth and prepared for light microscope with H-E staining. At 2 weeks after surgery, therer were rapid osteogenesis phenomenon on the defected area of the PDGF only treated group and early trabeculation pattern was made with new osteoid tissue produced by activated osteoblast. Bone formation was almost completed to the fornix of furcation by 8 weeks after surgery. New cementum fromation was observed from 2 weeks after surgery, and the thickness was increased until 8 weeks with typical Sharpey’s fibers reembedded into new bone and cementum. In both PDGF-BB with TCP group and PDGF-BB with Collagen group, regeneration process including new bone and new cementum formation and the group especially in the early weeks. It might be thought that the migration of actively proliferating cells was prohibited by the graft materials. In conclusion, platelet-derived growth factor can promote rapid osteogenesis during early stage of periodontal tissue regeneration.