• Journal of Periodontal and Implant Science
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• v.32 no.1
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• pp.173-186
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• 2002

The purpose of this study was to evaluate effect of platelet rich plasma on the treatment of Grade II furcation involvement, with Demineralized Freeze-Dried Bone(Dembone(R)) and bioabsorable membrane(BioMesh(R)) in humans by digital subtraction radiography. 12 teeth(control group) were treated with Demineralized Freeze-Dried Bone(Dembone(R)) and bioabsorable membrane(BioMesh(R)), and 12 teeth(test group) were treated with Demineralized Freeze-Dried Bone(Dembone(R)), bioabsorable membrane(BioMesh(R)) and Platelet Rich Plasma. The change of bone density was assessed by digital subtraction radiography in this study. The change of mineral content by as much as 5%(vol) could be perceived in the subtracted images. The change of mineral content was assessed in the method that two radiographs are put into computer program to be overlapped and the previous image is subtracted by the later one. Both groups were statistically analyzed by Wilcoxon signed Ranks Test and Mann-whitney Test using SPSS program (5% significance level). The results were as follows: 1. In test group, the radiopacity in 3 months after surgery were significantly increased than 1 month after surgery(p<0.05). However. there were no significant difference between 1 month after surgery and 3 months after surgery in control group(p>0.05). 2. In test and control group, the radiopacity in 6 months after surgery were significantly increased than 1 month after surgery(p<0.05) 3. In test and control group, the radiopacity in 6 months after surgery were significantly increased than 3 months after surgery(p<0.05). 4. There were no significant difference between test group and control group at 1 month, 3 months after surgery, but radiopacity in test group were significantly increased than control group at 6 months after surgery(p<0.05). In conclusion, Platelet Rich Plasma can enhance bone density.

• Journal of Periodontal and Implant Science
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• v.32 no.1
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• pp.161-172
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• 2002

The present study evaluated the effects of guided tissue regeneration using xenograft material(deproteinated bovine bone powder), with and without biodegradable membrane in beagle dogs. Contralateral fenestration defects (6 ${\times}$ 4mm) were created 4 mm apical to the buccal alveolar crest of maxillary premolar teeth in 5 beagle dogs. Deproteinated bovine bone powders were implanted into fenestration defect and one randomly covered biodegradable membrane (experimental group). Biodegradable membrane was used to provide GTR. Tissue blocks including defects with soft tissues which were harvested following four & eight weeks healing interval, prepared for histo-phathologic analysis. The results of this study were as follows. 1. In control group, at 4 weeks after surgery, new bony trabecular contacted with interstitial tissue and osteocytes like cell were arranged in new bony trabecule. Bony lamellation was not observed. 2. In control gruop, at 8 weeks after surgery, scar-like interstitial tissue was filled defect and bony trabecule form lamellation. New bony trabecular was contacted with interstitial tissue but defect was not filled yet. 3. In experimental group, at 4 weeks after surgery, new bony trabecular partially recovered around damaged bone. But new bony trabecular was observed as irregularity and lower density. 4. In experimental group, at 8 weeks after surgery, lamella bone trabecular developed around bone cavity and damaged tissue was replaced with dense interstitial tissue. In conclusion, new bone formation regenerated more in experimental than control groups and there was seen observe more regular bony trabecular in experimental than control groups at 4 weeks after surgery. In control group, at 8 weeks after surgery, the defects was filled with scar-like interstitial tissue but, in experimental group, the defects was connected with new bone. Therefore xenograft material had osteoconduction but could not fill the defects. We thought that the effective regeneration of periodontal tissue, could be achieved using GTR with biodegradable membrane.

• Journal of Periodontal and Implant Science
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• v.35 no.3
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• pp.703-718
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• 2005

The purpose of this study was to evaluate the clinical efficacy of guided tissue regeneration(GTR) technique using chitosan nanofiber membrane and to compare it to the clinical efficacy following GTR using PLA/PLGA(copolymer of polvlactic acid and polylacticglycolic acid) membrane in mandibular class II furcation defects in human. The chitosan nanofiber membranes were applied to the mandibular class II furcation defects of 13 patients(test group) and PLA/PLGA membranes were applied to those of 11 patients(control group). Probing pocket depth, clinical attachment level, gingival recession, plaque index and gingival index were measured at baseline and 3 months postoperatively. Vertical and horizontal furcation defect depth were measured at surgery. Both groups were statistically analyzed by Wilcoxon signed Ranks Test and Mann-Whitney Test using SPSS program. The results were as follows: 1. Probing pocket depth, clinical attachment loss and gingival index were significantly reduced at 3 months postoperatively compared to values of baseline in both groups(p<0.05). 2. Gingival recession and plaque index were not significantly decreased at 3 months postoperatively compared to values of baseline in both groups. 3. No significant difference between two groups could be detected with regard to changes of probing pocket depth, gingival recession, clinical attachment level, plaque index and gingival index at 3 months postoperatively. In conclusion, chitosan nanofiber membrane is effective in the treatment of human mandibular class II furcation defects and a longer period study is needed to fully evaluate the outcomes.

• The korean journal of orthodontics
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• v.34 no.3 s.104
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• pp.253-260
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• 2004

Frictional force between the orthodontic bracket and arch wire during sliding tooth movement is related to many factors, such as the size, shape and material of both the bracket and wire, ligation method and the angle formed between the bracket and wire. There have been clear conclusions drawn in regard to most of these factors, but as to the effect of bracket width on frictional force there are only conflicting studies. This study was designed to investigate the effect of bracket width on the amount of frictional forces generated during clinically simulated tooth movement. Three different widths of brackets $(0.018{\times}0.025'\;standard)$ narrow (2.40mm), medium (3.00mm) and wide (4.25mm) were used in tandem with $0.016{\times}0.022'$ stainless steel wire. Three bracket-arch wire combinations were drawn on for 4 minutes on a testing apparatus with a head speed of 0.5mm/min and tested 7 times each. To reproduce biological conditions, dentoalveolar models were designed with indirect technique using a material with similar elastic properties as periodontal ligament (PDL). In addition, to minimize the effect of ligation force, elastomer was used with added resin, which was attached to the bracket to make up for the discrepancies of bracket width. The results were as follows: 1. Maximum frictional force for each bracket-arch wire combination was: Narrow (2.40mm): $68.09\pm4.69gmf$ Medium (3.00mm): $72.75\pm4.98 gmf$ Wide (4.25mm): $72.59\pm4.54gmf$ 2. Frictional force was increased with more displacement of wire through the bracket slot. 3. The ANOVA psot-hoc test showed that the bracker width had no significant effect on frictional force when tested under clinically simulated conditions(p>0.05).

• The korean journal of orthodontics
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• v.27 no.2
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• pp.283-296
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• 1997

Stomatognathic system is a complex one that is composed of TMJ, neuromuscular system, teeth and connective tissue, and all its components are doing their parts to maintain their physiological relationships. Mandible, in particular, performs various functions such as mastication, speech, and deglutition, the muscular activities that determine such functions are signalled by numerous types of proprioceptors that exist in periodontal membrane, TMJ, and muscles to be controlled by complicated pathways and mechanics of peripheral and central nervous system. Orthodontic treatment, especially when accompanied by orthognathic surgery, brings dramatic changes of stornatognat is system such as intraoral proprioceptors and muscle activities and thus, changes in patterns of mandibular function result The author tried to analyze changes in patterns of mandibular movement and physiologic activities of surrounding muscles in Skeletal Class III ortlrognathic surgery patients who presently show a great increase in numbers. The purpose of this study was to draw some objective guidelines in evaluating funclierual aspects of orthognathic surgery patients. Mandibular functional analysis using Biopak was performed for skeletal Class III prognathic patients who underwent IVRO(lntraoral Vertical Ramus Osteotmy), and the following results were obtained: 1. Resting EMG was greater in pre-surgical group than the control group, and it showed gradual decrease after the surgery. Clenching EMG of masseter and anterior temporalis of pre-surgical group was smaller than those of control group, they also increased post-surgically, and significant difference was found between pre-surgical and post-surgical(6 months) groups. 2. Resting EMG of anterior ternporalis was greater than that of all the other muscles, but there was no significant difference. Clenching EMG of anterior temporalis and masseter were greater than those of the other muscles with statistical difference. In swallowing, digastric muscle showed the highest EMG with statistical significance. 3. Limited range of mandibular movement was shown in pre-surgical group. Significant increase in maximum mouth opening was observed six months post-surgically, and significant increase in protrusive movement was observed three months post-surgically.

• The korean journal of orthodontics
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• v.28 no.4 s.69
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• pp.563-580
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• 1998

This study was designed to analysis the displacement and stress distribution of individual tooth by orthodontic force during distal on masse movement of the maxillary dentition. In this study, three dimensional finite element analysis was used. Author made the finite element model of maxillary teeth, periodontal ligament, alveolar bone and bracket with anatomic and physiologic characteristics on computer. Author analysed and evaluated the displacement and stress distribution of individual tooth when extraoral force, Class II intermaxillary elastics, ideal arch wire, MEAW and tip back bend were used for distal on masse movement of the maxillary dentition. These analyses were also applied in the case of the maxillary second molar were not extracted. Author compared the results of the cases which maxillary second molar were extracted or not. The results were expressed quantitatively and visually. Author obtained following results, 1. When anterior headgear was applied, the posterior translation, posterior tipping, and vertical displacement of teeth were produced more in the anterior segment of the dentition. 2. When Class II intermaxillary elastics were applied in the ideal arch wire, the teeth displacement were usually produced in the anterior segment. But when tip back bend were added in the ideal arch wire, the orthodontic force produced by elastics were transmitted to the posterior segment. As increasing the tip back bend, posterior translation and lingual tipping of anterior teeth were decreased, posterior translation and tipping displacement of posterior teeth were increased, and extrusion of anterior teeth by Class II elastics were decreased 3. When MDAW and Class II elastics were applied, the teeth movement were sir flu with the case of ideal arch wire and Class II elastics, but more small and uniform teeth displacement were produced Compared with the ideal arch wire, posterior tipping of the posterior segment were more produced than lingual tipping displacement of the anterior segment. 4. When the maxillary second molar without orthodontic appliance existed, the displacement of maxillary first molar were decreased.

• The korean journal of orthodontics
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• v.31 no.3 s.86
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• pp.311-323
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• 2001

One of the various mechanics used to treat unilateral Class II malocclusion is head gear with asymmetric face bow. We made the finite element models of unilateral Class II maxillary dental arch and power arm asymmetric face bow. We designed this experiment to observe stress distribution of periodontal ligament, reaction force, and displacement and to understand force system, so to predict the therapeutic effect. On the basis of computerized tomograph of maxillary dental arch of 25 years old male with normal occlusion without extraction and orthodontic treatment history, we made finite element models of maxillary dental arch and periodontal ligament. Then we modified that model to unilateral maxillary Class II malocclusion model of which maxillary left molar displaced mesially. Also, We made finite element model of asymmetric face bow of which right outer bow shorter than left by 25mm(RMO, Penta-FormTM/Medium size, 0.045 inch iner bow, 0.072 inch outer bow). After that, retraction force of 250g, 300b, 350g were applied to maxillary first molar. We concluded as follow. 1. The Net force that both maxillary first molars were received increased as the retraction force increased. Mesially positioned tooth received more force than normally positioned tooth. But, both tooth were received distal force, so distal movement occured. 2. Both tooth received buccal lateral force. In analysis of force element, as the retraction force were increased, force of X-axis at mesially positioned tooth decreased, and force of X-axis at normally positioned tooth increased. so lateral force component moved to the side received less force from more force. 3. There were rotation, tipping with distal movement in maxillary first molar. As retraction force were increased, rotation and tipping also increased. More tipping and rotation occured at the side received more force, that is, mesially positioned tooth. Though it Is small change, displacement of same pattern occur in normally positioned tooth

• The korean journal of orthodontics
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• v.32 no.1 s.90
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• pp.9-18
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• 2002

The present study hypothesized that the double keyhole looped archwire plays a positive role for the sake of translatory movement and/or controlled tipping of upper 6 anteriors, and secures anchorage control as well. The purposes of the study were to evaluate the changes in lateral cephalograms during orthodontic treatment with DKHLs and to compare the skeletal & dental changes before- & after-treatment. The materials of this study were lateral cephalograms of 20 adult patients with upper dentoalveolar protrusion both in class I and in class II Division1 malocclusion. Lateral cephalograms were taken before and after orthodontic treatment with upper 1st bicuspid extraction and DKHLs. The results were obtained as follows : 1. There were no statistically significant differences in skeletal measurement except SNB and PTFH between before- & after-treatment. The major changes were in dentoalveolar region. 2. After treatment, there were statistically significant decrease in dental measurement except interincisal angle. 3. Both upper & lower lip protrusion was decreased. 4. There were statistically differences in upper anterior crown horizontal & root vertical dimension(7.08 ${\pm}$ 2.14 mm, 2.38 ${\pm}$ 1.15 mm, p<0.01). 5. There were statistically differences in upper posterior dental(both crown & root) horizontal dimension(2.48 ${\pm}$ 0.99 mm, 2.05 ${\pm}$ 0.91 mm, p<0.01).

• Journal of Periodontal and Implant Science
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• v.29 no.3
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• pp.539-553
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• 1999

The purpose of this 6-months study was to compare the clinical and radiographic outcomes following guided tissue regeneration treating human mandibular Class II furcation defects with a bioabsorbable BioMesh barrier(test treatment) or a nonabsorbable ePTFE barrier(control treatment). Fourteen defects in 14 patients(mean age 44 years) were treated with BioMesh barriers and ten defects in 10 patients(mean age 48 years) with ePTFE barriers. After initial therapy, a GTR procedure was done. Following flap elevation, root planing, and removal of granulation tissue, each device was adjusted to cover the furcation defect. The flaps were repositioned and sutured to complete coverage of the barriers. A second surgical procedure was performed at control sites after 4 to 6 weeks to remove the nonresorbable barrier. Radiographic and clinical examinations(plaque index, gingival index, tooth mobility, gingival margin position, pocket depth, clinical attachment level) were carried out under standardized conditions immediately before and 6 months after surgery. Furthermore, digital subtraction radiography was carried out. All areas healed uneventfully. Surgical treatment resulted in clinically and statistically equivalent changes when comparisons were made between test and control treatments. Changes in plaque index were 0.7 for test and 0.4 for control treatments; changes in gingival index were 0.9 and 0.5. In both group gingival margin position and pocket depth reduction was 1.0mm and 3.0mm; clinical attachment level gain was 1.9mm. There were no changes in tooth mobility and the bone in radiographic evaluation. No significant(p${\leq }$0.05) difference between the two membranes could be detected with regard to plaque index, gingival index, gingival margin position, pocket depth, and clinical attachment level. In conclusion, a bioabsorbable BioMesh membrane is effective in human mandibular Class II furcation defects and a longer period study is needed to fully evaluate the outcomes.

• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.2
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• pp.446-452
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• 1999

Ectopic eruption of the first permanent molar means the first permanent molar assumes an atypical path of eruption resulting in premature atypical resorption of the second primary molar. If the reversible eruption does not occur, early loss of the second primary molars results in space loss, mesial tipping of the first permanent molar, impaction of the second premolar, buccal segment crowding and overeruption of opposing tooth. The main objectives of treatment are (1) to prevent loss of the second deciduous molars so it can continue to serve as a space maintainer and (2) to regain lost arch length, allowing the second premolar to erupt into normal position. The optimal treatment approach depends on a number of factors including the clinical eruption status of /6/, the change in position of /6/, the amount of enamel ledge of /E/ entrapping /6/, the mobility of /E/, and the presence of pain or infection. Unilateral appliance to correct the mesial angulation of ectopic permanent first molars, as in the majority of the appliance designs, would produce a resultant force that would further enhance the space loss. A bilateral support similar to the holding arch design is recommended to maximize the anchorage. These case reports present the successful result of preserving space for the second premolar in treatment of ectopic eruption of the first permanent molar using Halterman appliance with bilateral anchorage on patients visiting department of pediatric dentistry in Samsung Medical Center.