A study on the dental arch characteristics of bialveolar protrusion patients using a three-dimensional digital model / 대한치과교정학회지

Recent beauty trends have caused an increase in the number of bialveolar protrusion patients seeking treatment of lip protrusion. But studies of these patients are not common. Studies using their dental models are especially rare. Dental models have been measured manually or through a computer by digitizing two dimensional images of models. Nowadays, we are able to study dental models more easily and accurately by utilizing the three-dimensional (3-D) laser scanner in dentistry. An investigation was carried out to evaluate the characteristics of the dental arch in a bialveolar protrusion group in comparison with a normal group using 3-D digital models. The normal group was composed of 20 subjects who were selected from students of the School of Dentistry, Kyungpook National University. The bialveolar protrusion group was composed of 20 subjects who visited for treatment at the Department of Orthodontics, Kyungpook National University Hospital. Tooth size, arch width and arch length were measured digitally, and arch shape and the shape of the palate were drawn. Based on the results of this study, the differences of the arch characteristics in the bialveolar protrusion group were that the size of the teeth was larger, mandibular canine width and 1st premolar width were wider, and arch length was longer than in the normal group. And there were differences in the arch shape and the shape of palate between the bialveolar protrusion and normal groups.

Comparison of histologic observation and insertional and removal torque values between titanium grade 2 and 4 microimplants / 대한치과교정학회지

The purpose of this study was to evaluate the light microscopic features and the maximum insertional and removal torque value of microimplants, made from titanium grade 2 or 4, in the tibia of 6 rabbits. First, the maximum torque values of microimplants at implantation were measured. After 2, 8, and 12 weeks of healing time, the microimplant-containing segments of tibia of 2 rabbits were removed and the maximum removal torque of each microimplant were measured. Comparisons of histologic examination and insertional and removal torque values were carried out for the two groups of microimplants. Removal torque values were significantly increased in both groups after 8 and 12 weeks as compared to 2 weeks after implantation. Other values measured did not show any statistically significant differences and there were no histological differences between grade 2 and 4 titanium. Based on these results, this study showed that there were no significant differences between grade 2 and 4 titanium. It seems better to use grade 4 titanium for making microimplants because grade 4 titanium is mechanically harder than grade 2 titanium and has similar retention.

Effects on osteoclast in periodontal ligament space by denerveation of inferior alveolar nerve in young and adult rats / 대한치과교정학회지

Osteoclast action is necessary for alveolar bone remodeling in orthodontic tooth movement. The nervous system has also been reported to be associated with bone remodeling. This study was aimed to investigate the changes of osteoclasts in the periodontal ligament (PDL) space after surgical resection of the inferior alveolar nerve (IAN). Experimental rats were divided into young and adult groups. A surgical resection procedure of the IAN was carried out in the left side of the mandible and a sham operation in the right side of the mandible. The number of osteoclasts on the bundle bone surface and the resorption activity of the osteoclasts were histomorphometrically measured. The changes in distribution of substance P (SP) immunoreactive (IR) nerve fiber were evaluated in the PDL and pulp. SP-IR nerve fiber was depleted in both the PDL and pulp of the IAN resection side in both groups, which confirmed the resection of IAN to be successfully conducted. The number of osteoclasts in the IAN resection side was significantly reduced in both the young and adult groups (p0.05 and p>0.05). The adult group showed that the number of osteoclasts reduced significantly (p0.05). These results suggest that surgical resection of the IAN and aging reduce the population of the recruited osteoclasts within the PDL, but don't affect on the osteoclastic resorption activity.

Three-dimensional finite element analysis of initial tooth displacement according to force application point during maxillary six anterior teeth retraction using skeletal anchorage / 대한치과교정학회지

The purpose of this study was to investigate the micro-implant height and anterior hook height to prevent maxillary six anterior teeth from lingual tipping and extruding during space closure. We manufactured maxillary dental arch form, bracket and wire, using the computer aided three-dimensional finite element method. Bracket was .022" x .028" slot size and attached to tooth surface. Wire was .019" x .025" stainless steel and .032" x .032" stainless steel hook was attached to wire between lateral incisor and canine. Length of hook was 8mm and force application points were marked at intervals of 1mm. Four micro-implants were implanted on alveolar bone between second premolar and first molar. The heights of them were 4, 6, 8, 10mm starting from wire. We analyzed initial displacement of teeth by various force application point applying force of 150gm to each micro-implant and anterior hook. The conclusions of this study are as the following : 1. When the micro-implant height was 4mm and the anterior hook height was 5mm and below, anterior teeth were tipped lingually. When the anterior hook height was 6mm and above, anterior teeth were tipped labially. 2. When the micro-implant height was 6mm and the anterior hook height was 5mm and below, the anterior teeth were tipped lingually. When the anterior hook height was 6mm and above, the anterior teeth were tipped labially. But lingual tipping of anterior teeth decreased and labial tipping increased when the micro-implant height was 6mm, compared with 4mm micro-implant height. 3. When the micro-implant height was 8mm and the anterior hook height was 2mm, the anterior teeth were tipped lingually. When the anterior hook height was 3mm and above, labial tipping movement of the anterior teeth increased proportionally. 4. When the micro-implant height was 10mm and the anterior hook height was 2mm and above, labial tipping of the anterior teeth increased proportionally. 5. As the anterior hook height increased, anterior teeth were tipped more labially. But extrusion occurred on canine and premolar area because of the increase of wire distortion. 6. Movement of the posterior teeth was tipped distally during maxillary six anterior teeth retraction using micro-implant because of the friction between bracket and wire. Based on the results of this study, we could predict the pattern of the tooth movement according to position of micro-implant and height of anterior hook. It seems that we can find the force application point for proper tooth movement in consideration of inclination of maxillary anterior teeth, periodontal condition, overjet and overbite

Elastic force degradation of synthetic elastomeric chain / 대한치과교정학회지

The purpose of this study was to evaluate the force degradation rate of synthetic elastomeric chains during space closing phase of orthodontic treatment. Two kinds of synthetic elastomeric chains(RMO, 3M) were selected which were commonly used in clinics. All of the samples were extended and tested for 4 weeks under the simulated intraoral condition. The results can be summarized as follows : 1. Time related residual force showed typical logarithm function. Residual force after 4 weeks was 41.2~64.6 % of original force, and difference between two kinds of elastomeric chain existed. 2. Elastic force decreased greatly during first 10 minutes, so 20~25 % of original force disappeared. After that, this decreasing tendency was diminished significantly, average rate of elastic force after 1 week to 4 weeks were 1.5 % demonstrating rather constant force. 3. Even though the same brand of elastomeric chiain was used, as extension rate of elastomeric chain increased, force degradation rate increased by decreasing of residual force.

The moment generated by the torque of the orthodontic rectangular wire : Three-dimensional finite element analysis / 대한치과교정학회지

The purpose of this study was to investigate the ideal clinical torque(In the SWA rectangular wire, the torque by the angle between the plane part and twisted part to move the tooth) of the orthodontic rectangular wire which produce the proper labiolingual movement of the single tooth during finishing stage of the orthodontic treatment. The clinical torque is the sum of the play and the active torque which generates the moment at the bracket. The play is calculated by the formula and the active torque is calculated by the computer aided three-dimensional finite element method. The finite element model was consist of the three brackets which formed a row and 3 kinds of orthodontic rectangular wire(stainless steel, TMA, NiTi) which inserted in brackets. Both sides of the model were twisted and the moment generated in the center bracket was calculated. The sizes of seven wires which were used commonly were .016" X .022", .017" X .022", .017" X .025", .018" X .025", .019" X .025", .020" X .025", .021" X .025". In 018" bracket, 016" X .022", .017" X .022", .017" X .025" wires were inserted and in 022" bracket, all the sizes of wires except .016" X .022" were inserted and tested. The following conclusions could be drawn from this study. 1. The moments generated on the same size of the wires by the same active torque were equal regardless of the bracket slot size. 2. The moments were increased with the size of the wires. The moment generated on the .021" X .025" wire was about 1.75 times as large as that on the .016" X .022" wire regardless of the material. 3. The moments were increased in the order of the NiTi, TMA, stainless steel. The moment of the TMA wire was 0.35 times as small as that of the stainless steel wire and the moment of the NiTi was 0.16 times as small as that of the stainless steel wire. 4. The moment was decreased as the interbracket distance was increased. 5. To get a desired moment with the specific size and material of the wire on the specific bracket slot, the formula and the results were displayed.

A longitudintal study of soft-tissue profile changes in Korean adults aged from 24 to 32 years / 대한치과교정학회지

The purpose of this study was to evaluate the soft-tissue profile changes from 24 to 32 years of age in Korean adults. The subjects used in this study consisted of 17 males and 8 females. The data obtained from the lateral cephalograms taken at age 24 and 32, were analyzed statistically. The obtained results were as follows : 1. During the observation period, there were no significant changes in the hard-tissue measurements in both sexes (p>0.05). 2. In the anteroposterior measurements of soft-tissue, the males had significant increase in chin area (Pog', Gn'), and the females had significant decrease in lower lip (LI) (p<0.05). 3. In the vertical measurements of soft-tissue, both sexes showed the increased tendency in upper lip length(Sn-Sto) where the males showed significant increase (p<0.05). 4. In general, the females and males had the increased tendency in soft-tissue thickness, especially significant increase in chin area (Pog', Gn') (p<0.05).

Osteodistraction of Midface Using Rigid External Distraction Device

We treated a total of 4 patients with midfacial hypoplasia, aged 12 to 19 years, using distraction osteogenesis between January 1998 and June 1999. In 3 patients with severe maxillary hypoplasia, we used rigid external distraction device developed by Dr. Polley. The distraction was performed from 5 days after Le Fort I osteotomy at a rate of 1 mm/day for 10 to 15 days. After distraction was completed, the device was left in place for another 6 weeks for bony consolidation. And then, an orthodontic face mask was used with elastic traction for 2 months. In one patient with partial hypoplasia of the midface, the osteotomized zygoma and a part of the maxilla was distracted selectively using rigid external distraction device a total of 15 mm. In the degree of SNA, mean value improved from 75.0(75.5, 75.0, 74.5) to 81.8(81.5, 83.0, 81.0) after 6 months later. In relapse rate, distracted length decreased from 10 mm to 6 mm, 15 mm to 8 mm, 13mm to 7 mm at 6 months later resulting in relapse rate of 44.3%. The follow-up period was from 7 to 26 months. Advantages of rigid external distraction device are highly effective technique of maxillary distraction, easy control of vector of distraction and no additional surgical procedure for removal of the device. In conclusion, the external distraction device is very useful for midface distraction.

Changes in CGRP-immunoreactive nerve fibers during expansion of midpalatal suture of the rat / 대한치과교정학회지

Midpalatal suture expansion if often used for patients having narrow maxillary arch, cleft palate, respiratory handicap with narrow nasal cavity. CGRP has been known as a modulator of pain transmission in central nervous system and a local effector to peripheral tissue causing vasodilation, increase of blood flow, modulation of immunesystem, regulation of macrophagic function and stimulation of bone formation. To investigate changes of CGRP-immunoreactive nerve fibers in midpalatal suture during the expansion, immunohistochemical study was performed by using rats. Experimental rats (10 weeks, 250 gm) were divided into five groups (control, 1, 4, 7, 14 days group (each n=4) and applied orthodontic force (approximately 200gm) to upper anterior incisors. Frozen sections of midpalatal suture area were immunostained by using rabbit antisera. The results were as follows: The CGRP-immunoreactive nerve fibers were hardly observed in control group. In 1 day group, the CGRP-immunoreactive nerve fibers were more increased around the vessels than control group. In 4 days group, the CGRP-immunoreactive nerve fibers were more increased than control group, but nor more increased than 1 day group. Vascular diameter was more enlarged. In 7 days group, especially, hematoxilin affinity of cells was remarkable and cells were arranged along the bone margin. The CGRP-immunoreactive nerve fibers were more reduced than 4 days group and vascular diameter was also reduced. In 14 days group. the CGRP-immunoreactive nerve fibers were similar to those of 7 days group and the irregularity of bone margin was almost recoverd. In Conclusion, the CGRP-immunoreactive nerve fibers may be related to intial neurogenic inflammatory reaction in expanding mid-palatal suture.

Prediction of the change of soft tissue profile on the lower face following retraction of incisors / 대한치과교정학회지

The purpose of this study was to evaluate the change of soft tissue profile on lower face following retraction of incisors through orthodontic treatment. 31 Korean women with bialveolar protrusion who were treated with 4 first bicuspid extraction were selected. All of samples were treated from above 17 years of age. Lateral cephalometric head films taken before and after treatment were analyzed statistically. The results were obtained as follows. The ratio of upper incisor retraction to upper lip retraction and lower incisor retraction to lower lip retraction were 1.54 : 1(r=0.746) and 0.92 : 1(r=0.584) respectively. It appeared during orthodontic treatment that UIS-LS was increased considerably and the others in soft tissue thickness measurements were slightly decreased. Analysis of correlation showed that the change of the upper lip(LS) with th change of maxillary central incisor(UIS) and the change of lower lip with the change of B point were most strongly correlated. The multiple regression equations were obtained to predict soft tissue profile change of lower face according to retraction of incisors.

The retrospective study on the prognosis of Class III malocclusion treatments / 대한치과교정학회지

The purpose of this study was to predict the prognosis of class III malocclusion treatments. 25 patients selected for this study were devided into two groups by the stability of dentitional, skeletal and soft tissue profile improvement. One was stable group which consisted of 12 children and the other was relapse group with 13 children. Various measurements in initial lateral cephalogram were calculated and analyzed by t-test, correlation coefficient and discriminant analysis. The results of this study were summarized as follows: 1. In both stable and relapse groups, there was not distinct difference in the antem-posterior skeletal relationship(P<0.05). 2. As the result of wits, AB to occlusal plane angle and occlusal plane to mandubular plane angle, the occlusal plane of relapse group was stopper than that of the stable group. 3. In correlation coefficient analysis, the overjet and the occlusal plane to mandibular plane angle showed significant correlations (P<0.001, P<0.01). 4. The discrminant function was obtained from three major influential measurements; overjet, AB to occlusal plane angle and articular angle, and this function could discriminate correctly in 88% of these samples.

c-Fos expression in the rat trigeminal sensory nucleus complex following tooth movement / 대한치과교정학회지

The c-fos is known as neuronal marker of second neurons which is activated by noxious peripheral stimulation. To investigate the changes of c-fos expression in the trigeminal n icleus complex during tooth movement, immunohistochemical study was performed. Experimental rats(9 weeks old, 210 gm, 21 rats) were divided into seven groups( normal, i hour group, 3 hour group, 6 hour group, 12 hour group, 1 day group, 3 day group). Rats in the normal group were anesthesized without orthodontic force. Rats in the experimental groups were applied orthodontic force (approximately 30 gm) to upper right maxillary molar. Frozen sections of brain stem were immunostained using rabbit antisera. The changes of c-fos expression were observed with respect to rostrocaudal distribution, laminar organization, and duration of orthodontic force application. The study results were as follows. · The c-fos nuclei in the dorsal part were observed from ipsilateral transition zone of subnucleus interpolaris and subnucleus caudalis to Ci cervical dorsal horn rostrocaudally. The maximal peak point was the rostral part of subnucleus caudalis. The greatest proportion of c-fos cells were located within lamina I and II. · The c-fos nuclei in the dorsal part were observed from the most caudal part of subnucleus interpolaris to the middle part of the subnucleus caudalis. · The number of c-fos imniunoreactive dot increased at 1 hour group, reached its maximum at the 3 and 6 hour groups, and showed a decreasing trend after 12 hours. These results imply that nociceptive stimulation caused by continuous orthodontic force might be modulated by transition zone of subnucleus interpolaris and subnucleus caudalis, subnucleus caudalis, C1 spinal dorsal horn.

Changes of CGRP immunoreactivity in rat trigeminal ganglion neurons during tooth movement / 대한치과교정학회지

GRP was known as the modulator of pain transmission in central nervous system and local effector to peripheral tissue causing vasodilation, increased blood flow, modulation of immune system, stimulation of endothelial cell proliferation, and stimulation of bone formation. Numerous study, therefore, were done to elucidate involvement of CGRP to tooth movement. To investgate the response of CGRP immunoreactive nerve cells according to cell size in trigemeinal ganglion during tooth movement, immunohistochemical study was performed using rat. Experimental rats(9 weeks old, 210 gm) were divided as six groups(normal(n=6), 3 hours group(n=5), 12 hour group(n=4), 1 day group(n=5), 3 day group(n=5), 7 day group(n=5)), and were applied orthodontic force (approximately 30 gm) to upper right maxillary molar. After frozen sections of trigeminal ganglions were immunostained using rabbit antisera, the changes of CGRP immunoreactive cells in regard to cell size distribution(small cell(up to 20 microgramm), medium cell(20-35 microgramm), large cell(above 35 microgramm)) were observed. The results were as follows 1. The percentage of CGRP immunoreactive cells to all nerve cells in trigeminal ganglion was 33.0% in normal control group, was decreased to 24.5% in 1 day group, and was increased to 41.8% in 7 day group. 2. The percentage of small, medium, and large cells expressing CGRP immunoreactivity in normal trigeminal ganglion to all CGRP immunoreactive cells were 51.3%, 44.0%, 4.7%, respectively. 3. The percentage of small cells with CGRP immunoreactivity to all CGRP immunopositive cells was increased in 3 hour and 12 hour groups. 4. The percentage of medium cells with CGRP immunoreactivity was increased in 3 day and 7 day groups. 5. The percentage of large cells with CGRP immunoreactivity was increased in 7 day group. Conclusively, the small cells with CGRP immunoreactivity in trigeminal ganglion respond to orthodontic force during initial phase of tooth movement, and later the medium and large with CGRP immunoreactivity respond.

The effects of static magnetic field and pulsed electromagnetic field on alkaline phosphatase and dna synthetic activity of ME3t3-E1 cells / 대한치과교정학회지

The purpose of this study was to evaluate the effects of magnetic field on cellular activity of MC3T3-El cells. The celular activity was monitored by alkaline phosphatase and DNA synthetic activity in control, static magnetic field and pulsed electromagnetic field groups. A static magnetic field was applied to the cell by placing one, two, three, four, and five samarium-cobalt magnets above and below each cell plate for 24hours per day. A pulsed electromagnetic field with a frequency of 100 herz was applied for 10 hours per day. After 10 days of magnetic field exposure, there were increase of alkaline phosphatase activity in static magnetic field groups consisted of one, two and three magnetic groups, Alkaline phosphatase activities were not significantly increased in four and five magnetic groups, Application of pulsed electromagnetic field did not result in significant increase in alkaline phosphatase activity compared to control. DNA synthetic activity in both static and pulsed electromagnetic field group were not significantly different from that in control group, The result of this study suggest that magnetic field could have effect on the metabolism of bone cells related to the cellular metabolic process,

The effects of continuous and intermittent compressive pressure on alkaline phosphatase activity of periodontal ligament cells / 대한치과교정학회지

The propose of this study was to evaluate the effect of cellular activity of PDL cells dependent on intermittent and continuous compressive force by determining the alkaline phosphatase activity. An intermittent and continuous compressive forces were applied on PDL cells at the confluent stage. The alkaline phosphatase activity was measured on control and experimental groups every 24, 48, 72hours. The experimental group were consist of continous and intermittent compressive group which were compressed by 300g/cm2 of diaphragm pump. The intermittent compressive group was connected by timer which was worked on 10 minutes and off 10minutes. The results were as follow; 1. The alkaline phosphatase activity of intermittent compressive group was lower than control group at 24 hours(P<0.05). 2. The alkaline phosphatase activity between each groups showed no significant difference at 48hours. 3. The alkaline phosphatase activity of continuous compressive group was significantly higher than control group at 72 hours(P<0.01).

The effect of fuctional lateral shift of mandible on the growth of mandible in growing rats / 대한치과교정학회지

This investigation examined the effect of lateral shift of mandible from functional occlusal interference on the growth of mandible and the growth pattern of mandible shown after the removal of occlusal interference. The followings were performed with the results below : the changes in mandible and condylar cartilage were studied in the experimental group with upper right, lower left incisors cut for 2 and 4 weeks- an 4-week-old rats and the experimental group which had cut for 4 weeks and suspended for 2 weeks. 1. In the 2-week experimental group, the left mandibular length, condylar length, mandibular height and condylar area seemed smaller than those on the right and the normal group ; the right mandibular length and condylar area were smaller than the normal group. 2. In the 4-week experimental group, left condylar area was smaller than the right, but due to the quick changes in adaptability of left mandible, right and left mandibular lengths were similar. compared with the normal group, however, mandibular length and condylar area still remained small. 3. In the 6-week experimental group, the left and the right appeared similar with the mandibular length remaining still shorter than the normal group. 4. In the sagittal plane, the proliferation of the cartilage layers of the left condylar cartilage of the 2-week group appeared to have general repression compared with the right and the normal group. The right side also showed repressed growth compared with the normal group. In the 4 and 6-week groups, however, it was similar to the normal group. 5. In condylar cartilage volume, no significant difference was noted in the comparisions of left and right of the experimental group, nor in the comparison of the same sides of experimental wand normal groups. Based on the above, in case of contralateral incisal cutting in rats, it was observed that the growth of mandible and condyle of the cutting side was repressed , at the same time, the quick adaptability led to similar changes of growth in left and right mandibles. But judging fiuui the similar phenomena throughout the whole experimental period in the changes of condylar cartilage volume in the experimental, right and left, and normal groups, the general overall growth of condylar cartilage was found unrepressed. It was also recognized that the growth of condylar cartilage can take in various directions.

A cephalometric analysis on esthetic facial soft tissue of Korean young adult female / 대한치과교정학회지

Cephalometric radiographs, frontal photographs and profile silhouette phogographs of 68 young adult female who were model or were recommended to have esthetic face were used in this study. 7 Students in department of Art of Kyungpook national university and 15 orthodontists estimated profile slides which were made of 3 Profile silhouettes in parallel with FH plane. Profile silhouettes were made of soft tissue profile line of cephalometric radiograph. Only orthodontists estimated frontal photographs. Students and orthodontists score 9 in excellent case, score 7 in good case, score 5 in average case, score 3 in poor case. Correlation analysis between orthodontists' esthetic concept and Artists' esthetic concept, between frontal view esthetics and profile view esthetics which estimated by orthotontists, between profile view esthetics and profile measurements which consisted of measurements of 38 female who were scored above 5 mean score in profile silhouette by orthodontists were done. And the finding in this study indicated the following 1. Correlation between orthodontists' esthetic concept and Artists' esthetic concept in profile silhouette was significant (r=0.67,P=0.0001). 2. Correlation between frontal view esthetics and profile view esthetics which estimated by orthodontist was significant (r=0.26,P=0.0381). 3. Measurements which had significant correlation between profile measurements and profile view esthetics wer Na-Pog, to N', BNV to Pog', BNV/B' -Pog', Ls-Li-Pog', Li-B'-Pog' Z angle(P<0.05). 4 Mean and standard deviation of profile measurements of 38 female were obtained.

The longitudinal growth changes of craniofacial structure in Korean adult (during the age of 24 to 31) / 대한치과교정학회지

Recently, according to the increase of adult patient, it is neccessory to understand the growth changes of adult after cessation of active pubertal growth in clinical orthodontics. The purpose of this study was to investigate the growth changes of craniofacial structure after active growth period(afult) in order to use reference in clinical orthodontics. Authors followed the 40 sample(male 25, female 15) from 24 to 31 years of age. By analyzing the serial cephalograms, authors could get the following findings. ? The mandible rotated clockwise in female, but not in male, and no incremental growth change in both genders. ? The anterior facial height and lower anterior facial height were increased in both genders, the increase of lower anterior facial height exceed the posterior facial height increase in famale. ? The cranial base was stable throughout observation period. ? The upper incisors uprighted slightly in female. ? There were quite great the individual variation in the growth change of ceaniofacial structure in adult.

Maturation of cervical vertebrae and mandibular growth changes / 대한치과교정학회지

In order to investigate the possibility of using a cervical vertebral maturation indicator as a mandibular growth indicator, the relationship of cervical vertebral maturation and mandibular & body height growth changes was assessed in biennial serial lateral cephalometric raadiographs of eighteen korean male and fourteen korean female while they were 8.5 to 185 years old. The following results were obtained. 1. It was a reliable method to evaluate skeletal maturation by using cervical vertebrae. 2. In general, cervical vertebral maturation stages of females were higher than those of males at the same age and there were significant differences in statistics at the age of 105, 14.5. 3. The age of a female at the same cervical vertebral maturation stage were earlier than that of a male. 4. In the case of males, significant Ar-Gn increases were found between stage 3 and 4,5 Ar-Go increases between stage 4 and 5. 5. In the case of females, significant S-Gn and Ar-Gn increases were found between stage 3 and 4. 6. Significant body height increases were found between stage 3 and 4 in both sexes. 7. The peak velocity of body height and mandibular length was observed between cervical vertebral maturation stage 3 and 4 in botli series. 8. The relationship between- inandibular & body height changes and specific maturation stage of cervical vertebra was found, therfore using a cervical vertebral maturation indicator as mandibular growth indicator is quite within realms of possibility.

A comparative study on chewing movement in normal occlusion and skeletal Class III malocclusion / 대한치과교정학회지

A comparative study was made on the chewing movements of normal occlusion and skeletal class III malocciusion. Thirty normal occlusion sybjects and twenty skeletal class III malocciusion patients were given chewing gums for the study ; using BioPAK system, the chewing movement on the frontal plane was recorded and analyzed. With a typical chewing path chosen representing each subject, chewing width, poening distance, poening and closing angles, maximum opening and closing velocities were observed. Seven characteristic patterns were classfied based on the types of chewing paths. The followings are the results : 1. Compared with the normal occlusion group, the skeletal class III malocclusion group showed more varied and vertical chewing patterns. 2. In comparision of chewing widths, skeletal class III malocclusion group showed marrower path than the mormal occlusion group(P0.05). 4. In opening and closing angles, skeletal class III malocclusion group showed more acute angles than the normal occlusion group(P0.05). 6. In the classification of chewing movement pattern, Type IV(chopping type)of skeletal class III malocclusion group showed a higher rate with 25.0% over 3.3% of normal occlusion group.