• The korean journal of orthodontics
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• v.26 no.2 s.55
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• pp.163-174
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• 1996

The purpose of this study was to examine the effects of bisphosphonate and indomethacin, blockers of bone resorption with different mechanisms, on alveolar bone remodeling. Male rats were divided into control, bisphosphonate and indomethacin groups, and then each group was divided info an experimental side and a control side according to the force application. Bisphosphonate(6.3mg/kg,$2.52x10^{-2}mol/L$) and indomethacin (9mg/kg, $2.52x10^{-2}mol/L$) were injected 6 hours and 1 hour before or 24 hours after the force application. The rats were killed 72 hours after the force application and histologic examination was perfomed. The values of serum acid phosphatase and lactate dehydrogenase were also measured in the control md experimental groups treated with bisphosphonate or indomethacin 1 hour before the force application. In the experimental side, the least number of osteoclasts was noted in the groups treated 1 hour before the force application with indomethacin or bisphosphonate, while there were no differences between the control and the groups treated with drugs 6 hours before or 24 hours after the force application. In the control side, the number of osteoclasts was not inecreased with no differences among the groups. Histologic examination revealed a severe alveolar bone resorption in the control group and the groups treated with indomethacin 6 hours before or 24 hours after the force application. Indomethacin treatment 1 hour before the force application and bisphosphonate treatment at any time significantly attenuated the bone resorption. Electron microscopically, ruffled border and clear zone of osteoclasts were observed in the control and indomethacin groups, while some osteoclasts were detached from the bone surface and exhibited dull cellular projections in the bisphosphonate groups. The bisphosphonate and indomethacin groups showed lower values of acid phosphatase and lactate dehydrogenase than the control group. The acid phosphatase value in the bisphosphonate group was lower than that in the indomethacin group, whereas there was no difference in the lactate dehydrogenase value between the groups. These results suggest that bisphosphonate reduces the activity of osteoclasts as well as the number of osteoclasts and that indomethacin reduces the number of osteoclasts without affecting the activity of osteoclasts. Bisphosphonate has a larger inhibitory effect on bone resorption md thus less limitation in the application time than indomethacin.

• The korean journal of orthodontics
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• v.26 no.2 s.55
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• pp.175-186
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• 1996

The purpose of this study was to examine the effects of mechanical and thermal fatigue on the shear bond strength(SBS) of stainless steel mesh brackets bonded to human premolar teeth with 3 no-mix adhesives. The stainless steel mesh bracket was Ormesh(Ormco, .022 slot) and three types of no-mix adhesives were Ortho-one(Bisco), $Monolok^2$(RMO), $System\;1^+$(Ormco). The $10^6$ loadcycles of $17.4{\times}10^2sin2{\pi}ftlg{\cdot}cm$ and the 1,000 thermocycles of 15 second dwell time in each bath of $5^{\circ}C\;and\;55^{\circ}C$ were acturated as mechanical and thermal fatigue stress, and SBS were measured after each fatigue test. The fracture sites were analyzed by stereoscope and scanning electron microscope. The results obtained were summarized as follows; 1. Before thermocycles, $Monolok^2$ showed the highest Knoop hardness number(KHN, $64.03kg/mm^2$) and $System\;1^+$ showed the lowest value($31.60kg/mm^2$). After thermocycling, $Monolok^2$ also showed the highest KHN($38.03kg/mm^2$) and $system\;1^+$ showed the minimum($20.87kg/mm^2$). The KHN of Ortho-one, $Monolok^2,\;System\;1^+$ significantly decreased after thermocycling (P<0.01). 2. In static shear bond test, three adhesives had no significant differences in the SBS(P>0.01). 3. After thermocycling test, $Monolok^2$ showed the maximum SBS($19.34{\pm}2.75MPa$) and Ortho-one showed the minimum SBS($13.66{\pm}2.23MPa$). The SBS of Ortho-one(P<0.01) and $System\;1^+$(P<0.05) significantly decreased after $10^3$ thermocycles. 4. The SBS of three adhesives after $10^6$ loadcycles were similar and were not significantly decreased compared with static group(P>0.01). 5. The failure sites were usually bracket/resin interface in all groups irrespective of experimental conditions.

• The korean journal of orthodontics
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• v.27 no.4 s.63
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• pp.549-557
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• 1997

This study was designed to investigate the attrition pattern in Angle Class III malocclusion with facial asymmetry. The sample consisted of three groups, the 20 subjects of normal occlusion group(Group I), the 12 subjects of class III malocclusion without facial asymmetry group(Group II) and 17 subjects of Class III malocclusion with facial asymmetry group(Group III). Attrition areas from canine to second molar on both sides in upper and lower arch, totally twenty, was marked by pencil and mesured by computer system(INTERGRAPH CO. USA) 2 times and the average value was used for date processing. Attrition areas from canine to second molar on both sides in upper and lower arch, totally twenty, was marked by pencil and mesured by computer system(INTERGRAPH CO. USA) 2 times and the average value was used for date Processing. All attrition areas were measured 2 times and the average value was used for data processing The data were statistically analyzed by SAS program. The results of this study were as follows. 1. Total attrition area in Group I was larger than in Group II and III. 2. There was no significant difference in attrition area between right and left side in each group, but attrition area in Group III was larger than in Group I and II. 3. In Group I, Maxillary attrition area was larger than mandibular attrition area, but in Group ll and III, there was no significant difference in attrition area between maxilla and mandible. 4. In Group III, the attrition area of deviated side was target than undeviated side 5. There was no significant difference in attrition area between chewing side and non-chewing side in each group. 6. The total attrition area was unaffected by gender.

• The korean journal of orthodontics
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• v.27 no.4 s.63
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• pp.569-584
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• 1997

The present study assessed the effects of Rapid Maxillary Expansion on head posture and hyoid bone position. For this study, 32 Angle's class III patients - hellman 3c $\~$ adult stage, mean age 12y9m - were selected and divided into two groups, A,B according to craniocervical angulation. Craniocervical angulation Increased in Group A and decreased in Group B after the therapy. And 23 Angle's class I persons $\~$ same hellman stage, mean age 12y7m $\~$ were selected (or the control group. Cephalometric analysis of skeletal pattern, pharyngeal space, head posture, hyoid bone position was performed. The results were as follows, 1. Comparison of skeletal pattern and pharyngeal space 1) All two groups(A,B) had Mandibular plane inclined inferiorly and no pharyngeal space change was obseved after RME therapy 2) Skeletal pattern and pharyngeal space of Group A, B were normal before and after treatment. 2. Comparison of head posture 1) Craniocervical angulation of Group A was increased after treatment. That of Group B was decreased and mandibular plane was inclined inferiorly after treatment. 2) Before treatment, craniocervical inclination was normal in Group A but larger than normal in Group B. After treatment, all two groups(A, B) had normal craniocervical angulation. 3. Comparison of hyoid bone position 1) After treatment, long axis of hyoid in Group A, B was not changed. Antero- posteriorly, hyoid position was changed posteriorly in Group A but no change was founded in Group B after treatment. Vertically, hyoid bone position were not changed in two groups except increase in APHFH in Group A after treatment 2) Long axis of hyoid bone was normal in Group A, B before and after treatment. Anteroposteriorly, hyoid bone position was more anterior than Group B, C before treatment but all the position of two groups had normal position after treatment. Vertical position of hyoid bone was normal in all two groups before and after treatment.

• The korean journal of orthodontics
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• v.26 no.2 s.55
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• pp.205-218
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• 1996

A given facial type can be considered as a syndrome in which various features are aggregated, so a single parameter is not sufficient to accurately identify a given facial type. This study was designed to identify & characterize the skeletal types that blend under the headline-'Cl III,deepbite'. Cephalograms of thirty-four untreated mixed dentition patients, selected mainly on the basis of clinical impression of Cl III with reduced lower face heights were studied. The following conclusion can be drawn. 1. Cl III malocclusion with reduced lower face height could be classified into three types. 2. Subtype 1 was identified by the following features : strong ramus, more anteriorly positioned upper molars without alveolar hypoplasia, acutely reduced Mn. plane angle. 3. Subtype 2 was characterized by a short ramus, sharply reduced postrior alveolar height, and normal Mn. plane angle. In general, this type had hypoplasia tendency in the vertical dimension. 4. In subtype 3, the AUFH occupying more percentage than ALFH was a outstanding feature. Ramal height was in normal range, alveolar hypoplasia and slightly reduced Mn. plane angle was observed. 5. The features of the subtypes were reflected in certain indices, which can be regarded as discriminative index. LAFH: if reduced, regardless of subtypes, indicates reduced lower ant. face height consistently. FHR: when this ratio is increased, it indicates subtype 1. FHI: when this ratio is in normal range, it indicates subtype 2. FPI: if reduced greatly, it indicates subtype 3.

• The korean journal of orthodontics
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• v.26 no.2 s.55
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• pp.153-162
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• 1996

Rapid maxillary expansion is widely used for the correction of anteroposterior discrepancies, constriction of the maxillary arch, etc. This experiment was undertaken to examine the serial changes in the osteogenesis as well as the collagen fiber bundles in the intermaxillary suture during the rapid maxillary expansion treatment. Four young female dogs aged 6 to 8 months old and not showing menarche yet were used for the experiment. The maxillary impression of dogs were taken, expansion device cast and Hyrax screw soldered at the midline in the 1st premolar area. RME device was delivered to the dogs and the activation of 0.25 mm per quarter-turn was done 2 times per day for 10 days until 5 mm separation was made. Separation of the maxilla was confirmed by X-ray. The animals were sacrificed on 0, 15, 30, 60 days from the finish of maxillary separation and preparations for light microscopy and surface electron microscopy were made. The sutures were cut into frontal serial sections for examination of the histological reactions. The following results were obtained and the conclusions made. 1. The edges of the two palatal plates bordering the midpalatal suture which at the beginning of the retention period were mainly composed of compact bone, underwent extensive resorption followed by new bone formation and gradually became spongy bone rich in bone marrow which in the 60 day retention animal became the compact bone with short intermaxillary suture space. During this transformation, newly formed trabecular bone tissues were added to the original margin. 2. Throughout the expansion period, the collagen fibers underwent successive changes such as stretching, loss of polarity, and finally fibrillogenesis. Towards the end of the expansion procedure, sharpey's fiber formation in newly formed bones were observed. 3. Bony spicules were found in the initial stage of retention on occlusal topographic X-rays, which later were confirmed to have ossified. 4. Judging from the histological changes occuring during the experimental expansion, excessive expansion will cause an excessive bleeding, and retard the remodeling of intermaxillary suture. According to the above results, the bone remodeling after rapid maxillary expansion was preceded by the migration of migratory cells into the intermaxillary suture area. The bone remodeling phenomena were on-going during the 2 months retention sample.

• The korean journal of orthodontics
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• v.27 no.4 s.63
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• pp.643-659
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• 1997

For the total treatment of skeletal malocclusions, 3-dimensional evaluation and diagnosis are essential. Although anteroposterior discrepancies can be evaluated through various methods, the satisfactory methods for evaluations of facial asymmetry and transverse discrepancies are yet to be found. The adequate diagnosis and treatment of transverse discrepancies may be more important in the maintenance of functional occlusion as well as for the stability of results obtained from orthognathic surgery than the anteroposterior or vertical discrepancies. Since the soft tissue effects from the transverse discrepancies may not be pronounced, especially when combined with anteroposterior or vertical discrepancies which have prominent characteristics, the differentiation of their effects may be difficult from visual inspection alone. Therefore it is essential that the normal facial proportions would be established from the posteroanterior cephalometry as a reference for the accurate diagnosis and treatment. The present study evaluates 76 subjects from Yonsei University freshmen with normal facial symmetry and occlusion. Posteroanterior cephalograms were taken from the subjects and the normal values and facial proportions are obtained. The results are as follows. 1. The transverse and vortical values from posteroanterior cephalometry and their ratio, with means and standard deviations are calculated. 2. The ratio of vertical values to transverse values is 0.837 (male 0.836, female 0.841). 3. The Proportion of maxillary and mandibular widths is 0.747 (male 0.745, female 0.752), with statistically significant correlation. 4. Various degree of significant correlations are observed in the following craniofacial widths; (Cranial width, Bizygomaticofrontal suture width, Facial width, Maxillary width, Upper & Lower Intermolar width, Mandibular width). 5. Although the facial height as well as other line measurements increase as the facial widths increase, angle measurement ($Bj\ddot{o}rk$ Sum, Mandibular Plane Angle, Gonial Angle), decreases and posterior to anterior facial height ratio increases, therefore indicating the tendency for a brachycephalic facial type. These results may be used as references for the treatment planning in orthognathic and orthodontic treatments for the dentofacial deformity patients.

• The korean journal of orthodontics
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• v.26 no.2 s.55
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• pp.233-244
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• 1996

The purpose of this study was to compare the shear bond strength obtained from ceramic and plastic brackets bonded with various light-cured adhesives and to evaluate their debonded failure sites. Plastic brackets, Transcend 6000, Signature and Starflre TMB brackets were bonded with Orthobond, Light Bond and Transbond on one hundred forty extracted human premolar teeth as manufacturer's descriptions. After thermocycling the brackets were debonded with an Instron universal testing machine and the debonded bracket base surfaces were inspected under stereoscope to evaluate the failure sites. Also the shear bond strength and failure patterns with different curing time and with two different source of light were compared. The results were as follows. 1. There were no statistically significant differences among the mean shear bond strength of Orthobond, Light Bond and Transbond in a same bracket group except Plastic bracket group(p<0.05). 2. The mean shear bond strength of each adhesive with different bracket groups showed statistically significant differences. Stafire TMB showed the highest shear bond strenght among the brackets in this study, but there was no statistically singnificant difference with Transcend 6000 while there was statistically significant difference with Signature.(p<0.05) 3. The various bonding failure patterns were occurred among different bracket groups but most of failure sites were bracket base -adhesive interfaces. 4. There were no statistically significant differences in shear bond strength between the groups with curing time of 10 second and 20 second, and between the groups with two different sources of light as long as sufficient light intensity(above $400mWcm^2$) were provided(p<0.05). According to the result, it should be considered in clinical use of ceramic bracket with light-cured adhesives that the shear strengths of ceramic brackets were influenced by the retention from of bracket base as well as the composition of bracket and there was no difference in the shear bond strenght among various light-cured adhesives used in this study.

• The korean journal of orthodontics
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• v.34 no.2 s.103
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• pp.131-142
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• 2004

The movement of tooth-bone segments by osteotomy can simultaneously shift tooth and surrounding alveolar bone in a relatively short period. The purpose of this study was to evaluate the tissue changes in pulp, periodontal ligament, and alveolar bone in rapid tooth-bone movement with osteotomy. The mandibular 3rd premolar of a dog was extracted and cortical bones of the buccal and lingual area were eliminated, and then cortical bones around the mesial and distal area of root, and below the root apex of the mandibular 4th premolar were osteotomized. After a one-week latency period, a tooth-borne distraction device was activated for 6 days. And pulp, periodontal ligament and alveolar bone were evaluated clinically, radiologically, histologically and immunohistochemically at 0, 1, 2, 4, 6, 8 weeks of the consolidation Period and conclusions were roached as follows. 1. Latency period didn't affect total amount or tooth movement and healing process of tissue during consolidation period. 2. Bone formation continued through 8 weeks of consolidation in distracted side, with a high peak at 1-2 weeks, and the lowest at 6-8 weeks or consolidation. 3. At 1 week of consolidation, alveolar bone resorption, osteoclast appearance and inflammatory cell infiltration were the most active, and dentinoclasts characteristically appeared on the pulp and pressure side of the periodontal ligament. 4. The expression of $TGF-\beta$ was area-specific, as it was strong-positive at bone matrix, osteoblast osteoclast of alveolar bone, and dentinoclast inside pulp, but weak in pulp, cementoblast and acellular cementum. 5. The expression of $TGF-\beta$ was generally observed at the initial 1-2 weeks of consolidation at vessels, periodontal ligament cells, and osteoblast near alveolar bone on the distraction side of the periodontal ligament, and was significantly decreased after 6 weeks of consolidation.

• The korean journal of orthodontics
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• v.34 no.2 s.103
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• pp.165-175
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• 2004

Information on the limits of treatment could allow for more rational treatment Planning and better results after treatment. From this point of view, this article has attempted to discuss the limits of orthodontic tooth movement. A relatively wider range of tooth movement is expected after Class III surgical-orthodontics than after conventional orthodontic treatment in general. The purposes of this Paper were: first, to evaluate the reliability of teeth position measuring gauge; and second, to elucidate the limits of orthodontic tooth movement. Dental casts of fifty-fine subjects were analyzed by using Set-up model checker (InVisitec Co., Korea) before and aster the Class III surgical-orthodontic treatment. The changes of maxillary and mandibular dental arch widths were also measured from the canines to the second molars. To test the inter-examiner reliability, randomly selected casts were measured by another examiner. Descriptive statistics and paired t tests were used to explain the tooth movement during treatment. The results showed a relatively good reliability of measuring instruments and a very diverse range of tooth movement. Collective changes by the orthodontic tooth movement evaluated in Class III surgical-orthodontics allowed for a suggestive interpretation of specific treatment patterns. Arch width changes during the inter-arch coordination were mainly the result of tipping in both buccal segments. Based on the results of this study, the possibility of a change in dentition as a result of orthodontic treatment should be understood in order to launch a well-organized plan of treatment.