• The Journal of Korean Academy of Prosthodontics
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• v.57 no.4
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• pp.448-455
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• 2019

Ameloblastoma is a benign odontogenic epithelial tumor with high recurrence rate and requires extensive resection of the surrounding tissue and reconstruction of defect site. Because of the anatomical limitation of the reconstruction site, prosthetic treatment with implants is the first recommendation. This is a case of prosthetic restoration of the reconstruction site with implant fixed prosthesis in patient who underwent mandibular resection and iliac bone reconstruction due to ameloblastoma. However 14 months after completion of implant prosthesis, adjacent natural tooth erupted unexpectedly, resulting in 1mm infra-occlusion occurred including posterior implant prosthesis and anterior natural teeth. In adults, implant infra-occlusion may occur due to residual growth after placement of the maxillary anterior implant. But this case, hypo-occlusion of molar implant and open bite of anterior natural teeth is occurred due to extrusion of adjacent tooth, is rare. Thus we report the treatment process including orthodontic treatment with intrusion of the posterior tooth, and investigate the causes of sudden, unexpected tooth extrusion.

• The korean journal of orthodontics
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• v.30 no.3 s.80
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• pp.317-333
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• 2000

The purpose of this study was to determine the proliferative activity of the osteoblasts and fibroblasts in the midpalatal area and to investigate the adjacent periodontal tissues of individual tooth following rapid expansion of the palate. Ten young adult dogs, aged approximately ten months, were used in the experiment. The experimental design was consisted of 1 week expansion group(Group E1, 3 dogs), 2 week expansion group(Group E2, 3 dogs), 2 week expansion and 2 week retention group(Group E3, 3 dogs), and control group(Group C, 1 dog). For each group, expansion screw was activated one time per day(1/4 turn;$90^{\circ}$) following Hyrax-screw application. The experimental animals in each group were sacrificed at 1, 2 and 4 weeks following palatal expansion. Maxillary tissue blocks were obtained and prepared ior the histomorphologic and immunohistochemical studies. Light mcroscope, polarizing microscope, and soft X-ray apparatus were used in this study, and following results were obtained. 1. In polarizing microscopic study, the expansion groups(E1 & E2) showed blue color representing bone resorption and new bone formation in midpalatal suture area. E3 groups skewed less blue color compared to the E1 and E2 group. But yellow color increased by calcification in the E3 groups. 2. Immunohistochemical study revealed that positive responses of the osteoblasts to PCNA and undifferentiated fibroblasts to EGF in E1 group were somewhat increased. Positive response to PCNA and EGF were increased in fibroblasts and the osteoblasts forming new bone in E2 group. In E3 group, the positive response cell concentrated the periphery of edge of palatal process in both PCNA and EGF. 3. Throughout the expansion period(E1 & E2), light microscopic study showed the edges of the extensive resorption and new palatal processes, indicating bone remodeling within the suture. E3 group exhibited less remodeling of midpalatal suture area. E2 group and E3 group showed cementum formation and resorption at the apex of 3rd premolar and 1st molar E3 group exhibited extensive hyalinized zone on the cervical portion of buccal side of 1st molar. 4. Soft X-ray analysis of E1 group showed hypomineralized defect and microfractures in various parts of the suture areas when compared with control animals. There was no significant difference in the degree of mineralization in the midpalatal suture region between the C and E3 groups. Tooth axis showed tipping of 3rd premolar and 1st molar in the E2 group and E3 group. Based upon these experimental results, it is concluded that the undifferentiated mesenchymal cells always presented in midpalatal suture area following RPE. Differentiated osteoblasts and fibroblasts possess proliferating cellular activity until the 2 week retention period. The posterior teeth are tend to tip buccally as RPE force applied. Retention group exhibited irreversible response with severe hyalinized zone on the buccal surface of the first molar.

• The korean journal of orthodontics
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• v.31 no.2 s.85
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• pp.209-223
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• 2001

At intrusion of upper anterior teeth in patient with periodontal defect, the use of three-piece base arch appliance for pure intrusion is required. To investigate the change of the center of resistance and of the distal traction force according to alveolar bone height at intrusion of upper anterior teeth using this appliance, three-dimensional finite element models of upper six anterior teeth, periodontal ligament and alveolar bone were constructed. At intrusion of upper anterior teeth by three-piece base arch appliance, the following conclusions were drawn to the locations of the center of resistance according to the number of teeth, the change of distal traction force for pure intrusion and the correlation to the change of vertical, horizontal location of the center of resistance according to alveolar bone loss. 1. When the axial inclination and alveolar bone height were normal, the anteroposterior locations of center of resistance of upper anterior teeth according to the number of teeth contained were as follows : 1) In 2 anterior teeth group, the center of located in the mesial 1/3 area of lateral incisor bracket. 2) In 4 anterior teeth group. the center of resistance was located in the distal 2/3 of the distance between the bracket of lateral incisor and canine. 3) In 6 anterior teeth group, the center of resistance was located in the central area of first premolar bracket .4) As the number of teeth contained in anterior teeth group increased, the center of resistance shifted to the distal side. 2. When the alveolar bone height was normal, the anteroposterior position of the point of application of the intrusive force was the same position or a bit forward position of the center of resistance at application of distal traction force for pure intrusion. 3. When intrusion force and the point of application of the intrusive force were fixed, the changes of distal traction force for pure intrusion according to alveolar bon loss were as follows :1) Regardless of the alveolar bone loss, the distal traction force of 2, 4 anterior teeth groups were lower than that of 6 anterior teeth group. 2) As the alveolar bone loss increased, the distal traction forces of each teeth group were increased. 4. The correlations of the vertical, horizontal locations of the center of resistance according to maxillary anterior teeth groups and the alveolar bone height were as follows : 1) In 2 anterior teeth group, the horizontal position displacement to the vortical position displacement of the center of resistance according to the alveolar bone loss was the largest. As the number of teeth increased, the horizontal position displacement to the vertical position displacement of the center of resistance according to the alveolar bone loss showed a tendency to decrease. 2) As the alveolar bone loss increased, the horizontal position displacement to the vertical position displacement of the center of resistance regardless of the number of teeth was increased.