Effect of extraction treatment on upper airway dimensions in patients with bimaxillary skeletal protrusion relative to their vertical skeletal pattern / 대한치과교정학회지

Objective@#To investigate dimensional changes in regional pharyngeal airway spaces after premolar extraction in bimaxillary skeletal protrusion (BSP) patients according to vertical skeletal pattern, and to further identify dentoskeletal risk factors to predict posttreatment pharyngeal changes. @*Methods@#Fiftyfive adults showing BSP treated with microimplant anchorage after four premolar extractions were included in this retrospective study. The subjects were divided into two groups according to the mandibular plane steepness: hyperdivergent (Frankfort horizontal plane to mandibular plane [FH-MP] ≥ 30) and nonhyperdivergent groups (FH-MP < 0.01). The upper airway variable representing greater decrease in the hyperdivergent group than in the nonhyperdivergent group was the MAS (p < 0.01). Posttreatment changes in FH-MP had negative correlation with changes in MAS (β = –0.42, p < 0.01) and inferior airway space (β = –0.52, p < 0.01) as a result of multivariable regression analysis adjusted for sagittal skeletal relationship. @*Conclusions@#Decreased pharyngeal dimensions after treatment in BSP patients showed no significant difference from the normal range of pharyngeal dimensions. However, the glossopharyngeal airway space may be susceptible to treatment when vertical dimension increased in hyperdivergent BSP patients.

Effect of extraction treatment on upper airway dimensions in patients with bimaxillary skeletal protrusion relative to their vertical skeletal pattern / 대한치과교정학회지

Objective@#To investigate dimensional changes in regional pharyngeal airway spaces after premolar extraction in bimaxillary skeletal protrusion (BSP) patients according to vertical skeletal pattern, and to further identify dentoskeletal risk factors to predict posttreatment pharyngeal changes. @*Methods@#Fiftyfive adults showing BSP treated with microimplant anchorage after four premolar extractions were included in this retrospective study. The subjects were divided into two groups according to the mandibular plane steepness: hyperdivergent (Frankfort horizontal plane to mandibular plane [FH-MP] ≥ 30) and nonhyperdivergent groups (FH-MP < 0.01). The upper airway variable representing greater decrease in the hyperdivergent group than in the nonhyperdivergent group was the MAS (p < 0.01). Posttreatment changes in FH-MP had negative correlation with changes in MAS (β = –0.42, p < 0.01) and inferior airway space (β = –0.52, p < 0.01) as a result of multivariable regression analysis adjusted for sagittal skeletal relationship. @*Conclusions@#Decreased pharyngeal dimensions after treatment in BSP patients showed no significant difference from the normal range of pharyngeal dimensions. However, the glossopharyngeal airway space may be susceptible to treatment when vertical dimension increased in hyperdivergent BSP patients.

Accuracy and precision of integumental linear dimensions in a three-dimensional facial imaging system / 대한치과교정학회지

OBJECTIVE: A recently developed facial scanning method uses three-dimensional (3D) surface imaging with a light-emitting diode. Such scanning enables surface data to be captured in high-resolution color and at relatively fast speeds. The purpose of this study was to evaluate the accuracy and precision of 3D images obtained using the Morpheus 3D(R) scanner (Morpheus Co., Seoul, Korea). METHODS: The sample comprised 30 subjects aged 24-34 years (mean 29.0 +/- 2.5 years). To test the correlation between direct and 3D image measurements, 21 landmarks were labeled on the face of each subject. Sixteen direct measurements were obtained twice using digital calipers; the same measurements were then made on two sets of 3D facial images. The mean values of measurements obtained from both methods were compared. To investigate the precision, a comparison was made between two sets of measurements taken with each method. RESULTS: When comparing the variables from both methods, five of the 16 possible anthropometric variables were found to be significantly different. However, in 12 of the 16 cases, the mean difference was under 1 mm. The average value of the differences for all variables was 0.75 mm. Precision was high in both methods, with error magnitudes under 0.5 mm. CONCLUSIONS: 3D scanning images have high levels of precision and fairly good congruence with traditional anthropometry methods, with mean differences of less than 1 mm. 3D surface imaging using the Morpheus 3D(R) scanner is therefore a clinically acceptable method of recording facial integumental data.

Correlation of expression and activity of matrix metalloproteinase-9 and -2 in human gingival cells of periodontitis patients

PURPOSE: Matrix metalloproteinases (MMPs) are capable of degrading extracellular matrix, and they are inducible enzymes depending on an inflammatory environment such as periodontitis and bacterial infection in periodontal tissue. Gingival inflammation has been postulated to be correlated with the production of MMP-2 and MMP-9. The objective of this study was to quantify the expression and activity of MMP-9 and -2, and to determine the correlation between activity and expression of these MMPs in human gingival tissues with periodontitis. METHODS: The gingival tissues of 13 patients were homogenized in 500 microL of phosphate buffered saline with a protease inhibitor cocktail. The expression and activity of MMP-2 and -9 were measured by enzyme-linked immunosorbent assay and Western blot analysis, and quantified by a densitometer. For the correlation line, statistical analysis was performed using the Systat software package. RESULTS: MMP-9 was highly expressed in all gingival tissue samples, whereas MMP-2 was underexpressed compared with MMP-9. MMP-9 activity increased together with the MMP-9 expression level, with a positive correlation (r=0.793, P=0.01). The correlation was not observed in MMP-2. CONCLUSIONS: The expression of MMP-2 and -9 might contribute to periodontal physiological and pathological processes, and the degree of MMP-9 expression and activity are predictive indicators relevant to the progression of periodontitis.

Histologic assessment of the biological effects after speedy surgical orthodontics in a beagle animal model: a preliminary study / 대한치과교정학회지

OBJECTIVE: Speedy surgical orthodontics (SSO), an innovative orthodontic treatment, involves the application of orthopedic forces against temporary skeletal anchorage devices following perisegmental corticotomy to induce movement of specific dental segments. Herein, we report the biological effects of SSO on the teeth and periodontal structures. METHODS: Five beagle dogs were divided into 2 groups and their 6 maxillary incisors were retracted en masse by applying 500 g orthopedic force against a single palatal mini-plate. Retraction was performed without and with perisegmental corticotomy in groups I and II, respectively. All animals were killed on the 70th day, and their periodontal structures were processed for histologic analyses and scanning electronic microscopy (SEM). The linear distance between the third maxillary incisor and canine was used as a benchmark to quantify the retraction amount. RESULTS: Retraction was markedly faster and retraction amount greater in group II than in Group I. Surprisingly, Group II did not show any root resorption despite extensive retraction, while Group I showed prominent root surface irregularities. Similarly, SEM showed multiple resorption lacunae in Group I, but not in Group II. CONCLUSIONS: SSO is an effective and favorable orthodontic approach for major en masse retraction of the maxillary anterior teeth.

Factors affecting orthodontically induced root resorption of maxillary central incisors in the Korean population / 대한치과교정학회지

OBJECTIVE: Orthodontically induced root resorption (OIRR) involves partial loss of cementum and dentin of teeth caused by routine orthodontic treatment. It decreases root length and influences the function of affected teeth. In this study, the treatment and patient factors causing apical root resorption in Koreans were determined. The observed factors were extraction, gender, age, displacement of root apex, total treatment period, total teeth length, and shape of the root. METHODS: The records of 137 patients treated with full, fixed edgewise appliances were obtained from the Department of Orthodontics, Dankook University Dental Hospital, from November 2007 to December 2008. Periapical radiographs of the maxillary central incisors and cephalometric radiographs of each patient were used to assess apical root resorption and type of tooth movement. RESULTS: The mean amount of resorption was 1.62 +/- 1.58 mm. The amount of resorption in the extraction and non-extraction groups was 2.10 +/- 1.64 mm and 1.18 +/- 1.39 mm, respectively. The amount of root resorption increased with the total tooth length. Severe root resorption (> 4 mm) was related to abnormal root shape (blunt, pointed, or eroded). CONCLUSIONS: The variables significantly related to OIRR were extraction, initial tooth length, and root shape.

Surface roughness analysis of ceramic bracket slots using atomic force microscope / 대한치과교정학회지

OBJECTIVE: This study was designed to measure the surface roughness at the slot floor of various ceramic brackets. METHODS: One kind of stainless steel bracket (Succes(R)), two kinds of monocrystalline brackets (Inspire Ice(R), Perfect(R)) and two kinds of polycrystalline brackets (Crystalline V(R), Invu(R)) were examined. Atomic force microscopy (AFM) was used to measure the surface roughness of each bracket. Data acquisition and processing were performed using SPIP(TM). RESULTS: The differences in values of Sa, Sq, and Sz in Invu(R) and Inspire Ice(R) were not statistically different from the control group Succes(R). The values of Sa, Sq, and Sz of Perfect(R) and Crystalline V(R) were greater than those of Succes(R). Differences of all the Sa, Sq, and Sz values between Perfect(R) and Crystalline V(R) were not statistically significant. CONCLUSIONS: It is concluded that the slot surfaces of Succes(R), Inspire Ice(R), and Invu(R) were smooth compared to those of Crystalline V(R) and Perfect(R).

Changes in surface roughness of bracket and wire after experimental sliding - preliminary study using an atomic force microscopy / 대한치과교정학회지

OBJECTIVE: The surface roughness of orthodontic materials is an essential factor that determines the coefficient of friction and the effectiveness of tooth movement. The aim of this study is to evaluate the surface roughness change of the brackets and wires after experimental sliding quantitatively. METHODS: Before and after experimental sliding tests, the surface roughness of stainless steel brackets, ceramic brackets, stainless steel wires, and beta-titanium (TMA) wires were investigated and compared using atomic force microscopy (AFM). RESULTS: After sliding tests, changes in the surface of the wire were greater than changes in the bracket slot surface. The surface roughness of the stainless steel bracket was not significantly increased after sliding test, whereas the roughness of ceramic brackets was decreased. Both the surface roughness of stainless steel and TMA wires were increased after sliding test. More changes were observed on the ceramic bracket than the stainless steel bracket. CONCLUSIONS: AFM is a valuable research tool when analyzing the surface roughness of the brackets and wires quantitatively.

The effects of electrical current from a micro-electrical device on tooth movement / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to determine whether an exogenous electric current to the alveolar bone surrounding a tooth being orthodontically treated can enhance tooth movement in human and to verify the effect of electric currents on tooth movement in a clinical aspect. METHODS: This study was performed on 7 female orthodontic patients. The electric appliance was set in the maxilla to provide a direct electric current of 20 micronA. The maxillary canine on one side was assigned as the experimental side, and the other as control. The experimental canine was provided with orthodontic force and electric current. The control side was given orthodontic force only. Electrical current was applied to experimental canines for 5 hours a day. The amount of canine movement was measured with an electronic caliper every week. RESULTS: The amount of orthodontic tooth movement in the experimental side during 4 weeks was greater by 30% compared to that of the control side. The amount of increase in tooth movement in the experimental side was statistically significant. The amount of tooth movement in the experimental side during the first two weeks was greater than that in the following two weeks. The amount of weekly tooth movement in the control side was decreased gradually. CONCLUSIONS: These results suggested that the exogenous electric current from the miniature electric device might accelerate orthodontic tooth movement by one third and have the potential to reduce orthodontic treatment duration.

Change in arch width in extraction vs nonextraction treatment / 대한치과교정학회지

OBJECTIVE: This study was performed to investigate the influences of extraction and nonextraction treatment on smile esthetics by measuring dental arch width changes. METHODS: Pretreatment and posttreatment study models of 30 first premolar extraction cases and 30 nonextraction cases were randomly selected to determine whether extraction treatment results in narrow dental arches, and a consequent unaesthetic smile. Arch widths were measured from the cusp tips of the canines and the first molars. Posterior arch widths were also measured at a constant arch depth derived by averaging randomly chosen nonextraction models. RESULTS: The intercanine widths increased significantly in the extraction sample, whereas the intermolar widths decreased significantly. The arch width at a standardized arch depth was significantly wider in the extraction subjects. CONCLUSION: These results elucidate that constriction in arch width is not a materialized consequence of extraction treatment. It leads to postulate that an esthetically compromising effect from narrow dental arches on smile is hardly anticipated with extraction treatment.

Friction of calcium phosphate brackets to stainless steel wire / 대한치과교정학회지

OBJECTIVE: Esthetic brackets which resemble the color of natural teeth have been widely used. But the frictional resistance of ceramic brackets, a typical esthetic bracket, is greater than that of metal brackets. The purpose of this study was to measure the frictional resistance of the new calcium phosphate brackets (CPB) which were recently developed and to evaluate its clinical usability by comparing the frictional differences of CPB with metal brackets and metal slot inserted ceramic brackets. METHODS: Experimental groups were CPB (Hyaline II, Tomy, Tokyo, Japan), metal bracket (Kosaka, Tomy, Tokyo, Japan) and metal slot inserted ceramic bracket (Clarity, 3M Unitek, Monrovia, CA, USA). All of the brackets had 0.022-inch slot sizes. The brackets were tested with 0.019 x 0.025 inch stainless steel wire (3M Unitek, Monrovia, CA, USA). A biologic model was used to simulate the situation which would occur during orthodontic treatment with fixed appliances. Retraction force was applied at a speed of 5 mm/min for 30 seconds. The frictional resistance was measured on a universal testing machine (Instron 4467, Instron, Norwood, MA, USA). RESULTS: CPB showed significantly higher friction than metal brackets (p < 0.05) and lower friction than metal slot inserted ceramic brackets (p < 0.01). CONCLUSIONS: CPB can be considered to be a useful orthodontic esthetic bracket with respect to frictional resistance, as its friction is remarkably lower than that of metal slot inserted ceramic brackets.

A comparative study of soft tissue changes with mandibular one jaw surgery and double jaw surgery in Class III malocclusion / 대한치과교정학회지

Numbers of postulations lie on the difference of integumental changes with two major surgical remedies of one jaw vs. two jaw surgery in skeletal Class III malocclusion. Accordingly it was the aim of the study to elucidate the skeletal profile changes with an accompanying disposition of soft tissues, consequently to yield the correlation and ratio of soft tissue changes with two types of surgical procedures, which in turn make it possible to predict the soft tissue outcomes by means of assembled regression equations. Cephalometric headfilms of fifty two adult skeletal Class III comprised of 26 maxillary advancement by Le Fort I osteotomy and mandibular setback by sagittal split ramus osteotomy simultaneously (double jaw surgery, group A), 26 mandibular setback alone (one jaw surgery, group B) were statistically analyzed. Group A manifested 72.4% soft tissue advancement to skeletal changes in the upper lip area, while group B appeared to have no statistically significant changes. The nasolabial angle showed more increment in group A than in group B, whereas the mentolabial angle illustrated more reduction in group B. The backward movement of soft tissue pogonion to skeletal change revealed 98% in group A, and 109% in group B. The double jaw surgery group characteristically revealed remarkable integ umental change in the upper lip area, while the one jaw surgery had major effects in the lower lip and soft tissue pogonion areas.

A study on treatment effects of Class III cases by second molar extraction / 대한치과교정학회지

This study aimed at investigating the skeletal, dentoalveolar, and soft tissue changes of Class III malocclusion cases treated by second molar extraction. The lateral cephalograms of 15 subjects with moderate Class III malocclusion by average ANB -1.4degrees and IMPA 85degrees were traced and the computerized superimposition of average craniofacial change was made. The data was gathered and statistically analyzed. The results were as follows: 1. Lower anterior facial height/anterior facial height increased by 0.6%(P<0.01), mandibular plane increased by 1.5degrees (P<0.05). 2. There was a slightly downward & backward rotation of the mandible. 3. Lower first molar tipped distally by 4.06mm(P<0.001), lower anterior teeth lingually tipped by 3.2degrees (P<0.05). 4. Retracted lower lip improved facial profile. This study may suggest that second molar extraction could be effective for a moderate Class III malocclusion to make distalization of the lower first molar easier and avoid severe lingual tipping of the lower incisor, if the lower third molar has a normal shape, good direction of eruption and adequate time for lower second molar extraction.

A comparative study of soft tissue profile between Korean and Caucasian young adults under NHP / 대한치과교정학회지

This study was performed to establish Korean soft tissue cephalometric norms, to compare the norms between sexes and between races, and then to suggest a guideline to execute orthodontic diagnosis and treatment planning for dentofacial deformities in Korean. Young Korean adults were selected. They were 27 males (23.8 2.6-year-old) and 20 females (22.5 1.7-year-old) who had harmonious facial balance. After taking lateral cephalograms under the natural head position which is widely known as a highly reliable and reproducible reference position, films were traced and analysing factors were measured as introduced by Arnett et al. Comparisons were done between male and female groups and between Korean and Caucasian groups using unpaired t-test. From the results it was concluded that Korean male had generally thicker lower facial soft tissue and smaller nasolabial angle, longer facial height, deeper facial depth, and more protrusive lower face than Korean female. From the comparison with Caucasian norms adopted from the research of Arnett et al., both Korean male and female showed longer facial lengths generally except less exposed maxillary incisor, and shorter facial depth than Caucasian counterparts. Also, both races showed similar horizontal position of maxillary structures from TVL (true vertical line), but there were more significant anteroposterior differences of maxilla-mandible in Korean groups. These results mean Korean had relatively more retruded mandibular structures from the reference line, TVL. Individuals who had harmonious facial balance showed similar facial angle, more or less 170 degree, regardless of sexes or races.

A study on the effects of Electrical stimulation by the miniature Electric device on the tooth movement and tissue remodeling / 대한치과교정학회지

Electric current is a highly probable way as a clinical tool for tooth movement. The purposes of this study were to determine the usefulness of exogenous electric currents in accelerating orthodontic tooth movement and to investigate the effects of electric-orthodontic treatment on the remodeling of the periodontal tissue histologically. The study was performed with six male cats weighing around 3kg. The electric device which is providing the direct electric current of 20microA was inserted to the removable appliance. The right and left maxillary canines were assigned as control and experimental sides respectively. The control canine was provided with orthodontic force (75gm) only and the experimental side was given the same amount of force and electricity. The lingual buttons were bonded to the maxillary canines and both sides of canines were retracted with NiTi coil spring. The electric device was adjusted to provide 20microA direct current to the experimental canines 5 hours a day. The amount of the canine movement was measured with electronic caliper every week. After 4 weeks of tooth movement, the animals were sacrificed and the histologic study was performed. The results of this study were as follows : 1. The application of a direct current to the experimental tooth significantly increased the final amount of orthodontic tooth movement. The amount of tooth movement after 28-day was 37% more in the experimental side. 2. The electrically stimulated tooth showed histologic evidence of significant increases in the amount of bones and matrix deposition in the area of tension. 3. In the compression side, the electric-orthodontic treatment stimulated bone resorption more extensively in the experimental canines. 4. After 28 days of electricity exposure and orthodontic force, the experimental side demonstrated significantly more osteoblasts, osteoclasts, capillaries and osteoid tissues, reflecting an increase in the local tissue's cellular activity. 5. Intermittent electrical stimulation (five hours a day) had effects to enhance orthodontic tooth movement and tissue remodeling. These results suggested that the low-intensity exogenous electric current by the miniature electric device might accelerate orthodontic tooth movement and bone remodeling in vivo and have the possibility to reduce the orthodontic treatment duration.

Dental and skeletal characteristics and growth in Class III malocclusion between skeletal ages of 10 and 14 / 대한치과교정학회지

The purpose of this study was to evaluate growth changes and skeletal characteristics of Korean children with Class III malocclusions from 10 to 14 years of skeletal age. Radiographs of 60 children with Class III malocclusion and 60 normal controls were assessed. Both groups were subdivided into 6 samples according to sex and skeletal age. Skeletal age was assessed using handwrist X-rays using the Greulich and Pyle norms. The Krogman-Walker plane (occipitale-maxillon) through Sella was used as a reference plane in this study with y-axis perpendicular to the x-axis. Six Student t-tests were conducted to compare the control group with the Class III group according to each gender and age. The characteristics of Class III malocclusion group compared to the control group included shorter anterior and posterior cranial base, shorter and retrusive maxilla, longer mandible, increased molar-incisor distance, retroclined lower incisors, labially proclined upper incisors, and anteriorly located mandibular molar, smaller upper and middle facial depth, and larger lower facial depth. Landmarks representing facial depth, size of maxilla and mandible, and their AP relationship including anterior facial height indicate that growth characteristic was determined early in life. But growth pattern of cranial base and some of the dental landmarks showed progressive divergence between Control and Class III groups with age. The position of the posterior border of the mandible was found to be significantly forward in both females and males by the age of 14 and at the anterior border in males and females at all ages. Hyperdivergent mandibular plane, changes in anterior segment of mandible, small anterior cranial base, and decrease in cranial base flexure was also noted.

A cephalometric investigation on the craniofacial configurations of Class II division 1 and 2 in Korean / 대한치과교정학회지

Numerous studies have revealed the similarities and discrepancies in two divisions of class II malocclusion, since these malocclusion groups have been postulated to be disparate criterion, much as classified under one diagnostic umbrella. This study was undertaken to describe the craniofacial configurations of class II division 1 and 2, and consequently to discriminate the morphologic differences between the two malocclusion groups in Korean sample. Lateral headfilms of 34 class II division 1 and 29 division 2 were employed, while those of 142 adults of normal occlusion served as a control. The landmarks were digitized and 26 variables were statistically analyzed for one way: 1. There manifested no statistically significant difference in maxillary position anteroposteriorly. Normal occlusion group exhibited most anteriorly positioned mandible, whereas class II division 1 showed the most retroposition. Class II division 1 disclosed clockwise rotation tendency of mandible, which resulted in position of the chin posteriorly. 2. Class II division 1 showed greater in SN to MP, SN to PP significantly than other groups. 3. Class II division 2 showed smaller gonial angle and larger mandibular body length than other groups. 4. Class II division 1 revealed greater anterior lower face height than other groups, whereas division 2 dictated significantly greater posterior face height. 5. Class II division 2 expressed the most retroclined lower incisor, while division 1 manifested the most proclination. The largest interincisal angle resided in Class II division 2 group. There were no significant differences in upper molar position anteroposteriorly.

A Cephalometric study on tooth movement pattern of maxillary 6 anteriors with double keyhole loops / 대한치과교정학회지

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 Division 1 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+/-2.14 mm, 2.38+/-1.15 mm, p<0.01). 5. There were statistically differences in upper posterior dental(both crown & root) horizontal dimension(2.48+/-0.99 mm, 2.05+/-0.91 mm, p<0.01).

Evaluation of orthodontic treatment outcomes and post-treatment changes by the PAR index / 대한치과교정학회지

The purposes of this study were to assess the treatment results in orthodontic department, Kyung Hee University, to evaluate the occlusion at 2 year follow-up control, in relation to the original malocclusion, and changes occurring in the follow-up period, and to determine whether treatment and posttreatment changes of the PAR index were related to the original Angle classification Dental study casts of 25 patients in permanent dentition were evaluated using Peer Assessment Rating (PAR) index. The PAR index was measured at the pretreatment stage, immediately after treatment, and at 2 years posttreatment. The following results were obtained : 1. The treatment reduced the PAR index by 85.05% and it indicates that KHDC clinic has a high standard of treatment 2. The follow-up result of 75.40% PAR score reduction implies a gain of 9.65% of posttreatment PAR score during follow-up period. 3. There is no relationship between the treatment changes of the PAR index and the orignal Angle classification.

Study on the growth of the mandible using wide open lateral cephalogram / 대한치과교정학회지

In proceeding with orthodontic treatment, the prediction for the shape, growth rate and growth direction of mandible plays a major role to set up the treatment plan and determine its period and prognosis. Various approaches being made so far have shown that the linear and angular measurement using lateral cephalograms are relatively accurate to estimate them. This study was purposed to find the shape of mandible more clearly by preventing the overlap of the Condyle head area which appears in lateral cephalogram, and to estimate its growth rate by comparing the growth quantity and ratio via lateral area measurement. This experimental was performed against 40 patients total, of which Class I of 14, Class II of 9 and Class III of 17 consist. Wide open lateral cephalograms of 40 patients were taken over average period of 4 Year 3 Months, then the linear and angular measurements were carried out with 11 itemized lists. Autocad R14 application program was utilized to draw their appearance, measure and compare their lateral area. As a result of study, conclusions were made as follows; 1. Mandibular body length (gonion-menton) tended to increase in order of CIII, CI and CII, and Mandibular body length of CIII group had a tendency to grow twice faster than that of CII group. 2. In lateral items such as Go-Me, A-Cd, B-Cp, E-F and G-H, CIII showed a significant increase on the year-average quantity and rate of the growth, and especially apparent difference was observed in CIII group rather than CII group. 3. For the 4 Year 3 Months period, the year-average growth quantity of lateral area of the mandible was 1.0 cm2 for Class I, 0.8 cm2 for Class II and 1.4 cm2 for Class III, which corresponds to 11.9%, 11.8% and 20.3% of growth ratio respectively. Thus, growth ratio almost 2 times more than other groups was observed in group CIII while growth ratio between group CI and CII has little difference. 4. Considering the results as above, it can be proposed that the difference in size of the mandible between groups is caused by the difference in the growth rate and growth quantity of the mandible, which generated in the middle of growth, rather than the difference in size of congenital Jaw-bone.