• The korean journal of orthodontics
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• 제36권2호
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• pp.136-144
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• 2006

The purpose of this study was to determine whether association exists between temporomandibular joint (TMJ) characteristics in transcranial radiographs and TMJ internal derangement and to evaluate the validity of transcranial radiographs in diagnosis of internal derangement. Transcranial radiographs and magnetic resonance imaging (MRI) of 113 TMJs from 76 subjects were used for this study and all TMJs were classified into 3 groups according to the results of MRI: normal disk position, disk displacement with reduction, and disk displacement without reduction. Transcranial analysis included linear measurement of joint spaces and condylar head angle measurement. To determine any relationship between transcranial measurements according to disk displacement, one-way ANOVA was used. The results showed that condyle-fossa relationship in standard transcranial radiographs had no relationships with disk displacement. And, as disk displacement progressed, condylar angle between head and neck increased significantly. This result can be interpreted that condylar head angle reflects structural hard tissue change according to internal derangement progress. But this is insufficient in the determination of internal derangement. Therefore, although still clinically helpful, the validity of standard transcranial radiographs to diagnose TMJ internal derangement was questioned.

• The korean journal of orthodontics
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• 제32권2호통권91호
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• pp.91-105
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• 2002

In general, orthodontists make problem lists and treatment plans based on norms of several cephalometric standards. But consideration of dentoalveolar compensation, which tends to maintain normal dental arch relationship in various skeletal jaw relationships, helps orthodontists make more individualized treatment objectives and plans. The purpose of this study was to classify skeletal patterns of normal occlusion samples by cluster analysis and to investigate the dentoalveolar compensation according to skeletal patterns. The subjects were consisted of 125 subjects who were normal occlusion samples at Seoul National University Dental Hospital, Department of Orthodontics. Lateral cephalograms in centric occlusion were traced and digitized. The skeletal patterns of normal occlusion samples were classified into three horizontal groups and three vertical groups by cluster analysis and ANOVA on the skeletal and dentoalveolar measurements among the groups were carried out. The results were as follows ; 1. Anteroposterior and vertical skeletal relationships of normal occlusion samples were very variable. 2. As the mandibular position was anterior to the maxilla, the maxillary incisors inclined more labially, the mandibular incisors more lingually, and the occlusal plane was flattened due to the anteroposterior dentoalveolar compensation. dentoalveolar height was decreased and upper posterior teeth was uprighted to the palatal plane and lower incisors and lower posterior teeth to the mandibular plane. 4. Lower incisors were more strongly associated with the dentoalveolar compensation than upper incisors according to the anteroposterior and vertical skeletal relationship.

• The korean journal of orthodontics
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• 제26권5호
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• pp.557-568
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• 1996

The purpose of this study was to analyze the growth changes of ODI and APDI with age on the three facial growth patterns. The biennial serial cephalometric radiographs of 19 male and 14 famale samples with normal occlusion during 10 years were used in this study. The samples were divided into three groups - drop type, neutral type, forward type - by the total change of the Y-axis during the periods of the study. The findings in this investigation indicated the following: 1. The mean values and standard deviations of each age group in each facial type of male and famale were obtained. 2. The difference of ODI and APDI among the 3 facial types was not significant through all observed ages(P)0.05). The size of ODI appeared large consistently in order of the drop, neutral, and forward type in both male and female through all observed ages. 3. The ODI and APDI were maintained without any charges with age during the periods of the study(p>0.05). 4. In correlation analysis between the total change of the Y-axis and 6 measurements, the AB plane angle and facial angle showed correlation in both male and female(p<0.05), the APDl in only female(p<0.001), but the ODI not appeared correlation in either male or female(p>0.05).

• The korean journal of orthodontics
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• 제23권2호
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• pp.249-261
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• 1993

This study was conducted to examine the growth change in external nose according to age which plays an important role in determining the facial profile, by analysing the biennial serial lateral cephalograms of 20 males and 20 females of mean 8.5 years old to 16.5 years old who have a normal occlusion. The results of this study were summarized as follows. $\cdot$ Both mean and standard deviation were obtained according to each item, sex and age for the male and female. $\cdot$ Nose heights of the male and female increased with increase in their age. The upper to lower nose height ratio somewhat decreased for both male and female with increase of age. The mean ratio was 3.69 : 1 for the male, respectively, and 3.83 : 1 for the female during this study．$\cdot$ The nose depth indicated the most significant increase of all items according to the increase of age, while the sagittal depth inicated higher value for the female than that of the male in the most age groups. $\cdot$ The nose inclination did not show a remarkable change during this study. $\cdot$ The proportions of growth completed at the earliest age showed the highest percentage for sagittal depth(male : $87.14\%$ & female : $91.29\%$). Also, the male indicated the lowest percentage in lower nose height $(73.04\%)$, while the female did the lowest in nose depth$(79.09\%)$. $\cdot$ There was shown the variable of the greatest correlation between the upper nose inclination and nose depth. $\cdot$ From this study, the whole external nasal growth was occurred downward and forward which was more frequent for forward growth than vertical growth.

• The korean journal of orthodontics
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• 제26권3호
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• pp.247-254
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• 1996

This study was performed to evaluate the hyoid bone position and airway in skeletal class III malocclusion and to prove the correlation between airway, hyoid bone position and mandibular position. The sample, considered of 47 class III malocclusion patients for experimmtal group and 52 class I malocclusion students for control group. Twenty three linear and angular measurements about hyoid bone position, airway size, mandibular position were taken from the lateral cephalograms. The differences between skeletal class III malocclusion group and normal occlusion group were compared and the correlation were evaluated statistically. The results obtained were as follows, 1. There were significant difference in S-APH, A-APH, N-APH, LAH-PBR, AA-PNS, PNS-ad between class I and class III malocclusion groups. 2. The hyoid bone was more anteriorly positioned in class III malocclusion group than class I malocclusion group and skeletal airway size in class III malocclusion group was smaller than class I malocclusion group. 3. There were significant difference in several measurements especially vertical and angular measurements of hyoid bone position and airway size between male and female. Usually the measurements in male were larger than female. 4. There were no significant correlation between hyoid bone position and airway size also airway size, and didn't showe significant correlation with mandibular position, 5. S-APH showed negative correlation with Wits appraisal and A-APH, N-APH showed positive correlation with Wits appraisal. On the contrary vertical measurements of hyoid bone position showed positive correlation with lower facial height.

• The korean journal of orthodontics
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• 제28권5호
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• pp.855-864
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• 1998

The purposes of this study were to evaluate the cephalometric characteristics of Korean female patients with Class II division 2 malocclusion and to compare Korean females with Caucasian females who had same type of malocclusion. All of the samples had Class II division 2 malocclusion with deep overbite (more than 4mm) and full permanent dentition. These samples were divided into two groups according to the races: Group 1(N=16; Korean females; average age=18Y 2M) and Group 2 (N:20; Caucasian females; average age=14Y 2M). The pretreatment lateral cephalograms were measured, analyzed and compared by using 38 variables and independent t-test. And the results were as follows: 1. Although there were no differences in Overbite, SN to mandibular plane angle, Palatomandibular plane angle, and FMA between Group 1 and 2, the other vertical relation variables of maxilla and mandible (SN to palatal plane angle, SN to occlusal plane angle, ODI) of Group 1 showed more clockwise rotation tendency of occlusal plane and less hypodivergency tendency than those of Group 2. 2. There were no differences in mandibular body length and ramus height between Group 1 and 2 except small upper genial angle of Group 1. There was less counterclockwise rotation tendency of mandible in Group 1. 3. There were no statistical significant differences in UAFH/LAFH and PFH/AFH between Group 1 and 2. 4. Although there were no differences of overjet and anteroposterior position of mandible between Group 1 and 2, the position of maxilla of Group 1 was more retropositioned than that of Group 2. 5. Except the more protrusion of lower incisor to A-Pog of Group 1, there were no differences of inclination and distance of upper and lower incisors to basal plane between Group 1 and 2. 6. The distance from upper- first molar to palatal plane showed no difference between Group 1 and 2. But the distance from lower first molar to mandibular plane of Group 1 was greater than that of Group 2. So it may be partially related to the clockwise rotation of occlusal plane and the less counterclockwise rotation tendency of mandible of Group 1. 7. Group 1 had more protrusive upper and lower lips than Group 2.

• The korean journal of orthodontics
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• 제27권2호
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• pp.221-230
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• 1997

It has been known that head posture may influence directly and/or indirectly the growth and development of craniofacial morphology and can also be influenced by the funtional demand of physiologic activity. It was reported that facial morphology has close relationships with hyoid bone position and head posture. In many previous studies, Natural Head Posture(NHP) was guided, and also it was shown that NHP has high degree of reproducibility. Otherwise, There was few study about the relationship of head posture, with routine cephalometric film which is used for clinical orthodontic purpose. In this study, according to the Wits and ANB of initial cephalometric film which was taken with vertical pendulum as representative of true vertical reference line. We classified the subjects which is comprised of 60 adult female patients into Class I, II, III (Cl I, II, III)and we tried to find out the correlation of head posture and hyoid bone position according to the classification of malocclusion. As a result of our research, we found the followigs. 1. In comparison of vertical position of hyoid bone relative to the cranial base. the position of hyoid bone of Cl III was lower than that of Cl II. 2. In comparison of anteriorpostes or position of hyoid bone, relative to the cervical column. The position of hyoid bone of Cl III was more anterior than that of a II 3. in comparison of vertical position of hyoid bone relative to mandible. There was no significant correlation aumoug the groups of malocclusion. 4. ANB and Wits showed no significant correlation with hyoid bone position. 5. The relative extension of head, which was noted in Cl II, showed negative with Sum, ANB. 6. In Cl II and Cl III, Post to Ant facial height showed positive correlation with NSL/VER.

• The Journal of the Acoustical Society of Korea
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• 제33권1호
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• pp.10-20
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• 2014

To study the water-entry impact noise, on-board experiment using a small launcher firing various objects was performed in the Yellow Sea. As the launcher fires a cylindrical object from the ship vertically, generated noise is measured with a hydrophone on the starboard of Chung-hae, Marine surveyor. Three types of cylindrical objects, which have noses of flat-faced, conical, and hemisphere, were used during the experiment. The measured noise exhibits a time-dependency which can be divided into three phases: (1) initial impact phase, (2) open cavity flow phase, (3) cavity collapse and bubble oscillation phase. In most cases, the waveform of bubble oscillation phase is dominant rather than that of initial impact phase. Pinch-off time, where a cavity begins to collapse, occurs at 0.18 ~ 0.2 second and the average lasting time of bubble was 0.9 ~ 1.3 second. The energy of water-entry impact noise is focused in the frequency region lower than 100 Hz, and the generated noise is influenced by the nose shapes, object mass, and launching velocity. As a result, energy spectral density on the bubble frequency is higher in the order of flat-faced, conical, hemisphere nose, and the increase of initial energy raises the energy spectral density on the bubble frequency in the cylinder body of same shape. Finally, we compare the measurements with the simulated signals and spectrum based on the bubble explosion physics, and obtain satisfactory agreements between them.

• The korean journal of orthodontics
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• 제26권4호
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• pp.349-358
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• 1996

To extract or not to extract permanent teeth for the correction of malocclusion has been a great debate in the history of orthodontics, and there is a variety of analytic methods and criteria to aid in the diagnosis. Extraction formulas that has been presented are many analytic methods that depend on arch length discrepancy, dental prominence, and skeletal pattern of the each patients. Of these analysis, the most important diagnostic factor is patient's skeletal pattern. Because the behavior of the dentition is closely dependent upon the skeletal pattern of each patient, dentition must be arranged within that person's skeletal frame. EI(Extraction Index) is composed of CF, interincisal angle, and lip position. CF is made of ODI and APDI that differentiate vertical and horizontal component of the skeletal pattern. So, EI not only represents patient's skeletal pattern, but also takes facial appearance into consideration. This study was undertaken to investigate EI and related cephalometric variables on the cephalogram of Korean adolescents which consisted of 153 persons with normal occlusion, harmonious skeleton and pleasing face. The following conclusions were obtained. 1. The mean value of the ODI is $73.5^{\circ}$, APDI $82.5^{\circ}$, CF $156.3^{\circ}$ 2. The mean value of the interincisal angle is $123.6^{\circ}$ 3. The mean distance of upper lip to E-line is 0.0mm, lower lip to E-line is 1.4mm. 4. The mean value of the EI is $153.8^{\circ}$.

• The korean journal of orthodontics
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• 제33권1호
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• pp.31-39
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• 2003

This study was performed to evaluate whether growth Prediction method can be used to diagnose and make treatment plan in skeletal Class III malocclusion patients or not. The sample was consisted of 25 patients(13 males, 12 females) who had been diagnosed with skeletal Class III malocclusion at first visit and after that had returned to take ortognathic surgery. Growth prediction performed with Ricketts' growth prediction method from first cephaogram. was compared with actual growth of the second cephalogram. The findings of this study were as follows ; 1. There was significant difference between actual growth and growth prediction in Porion Location, Ramus Position, Facial Depth, Facial Axis, Mandibular Plane angle, Maxillary Convexity. So, for these items Ricketts' growth prediction method is not proper to predict growth. 2. Although the growth amount of mandibular body was similar to normal growth amount, mandible was positioned anteriorly because of Porion Location and Ramus Position. 3. In skeletal Class III malocclusion patients, the tendency of mandibular prognathism might be aggreviated because of anterior placement of ramus and anterosuperior rotation of Pogonion.