• The korean journal of orthodontics
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• v.37 no.3 s.122
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• pp.182-191
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• 2007

Objective: The purpose of this study was to evaluate the validity of midsagittal reference (MSR) planes constructed in maxillofacial 3D images. Methods: Maxillofacial computed tomography (CT) images were obtained in 36 normal occlusion individuals who did not have apparent facial asymmetry, and 3D images were reconstructed using a computer software. Six MSR planes (Cg-ANS-Ba, Cg-ANS-Op, Cg-PNS-Ba, Cg-PNS-OP, FH${\perp}$(Cg, Ba), FH${\perp}$(Cg, Op)) were constructed using the landmarks located in the midsagittal area of the maxillofacial structure, such as Cg, ANS, PNS, Ba and Op, and FH plane constructed with Po and Or. The six pairs of landmarks (Z, Fr, Fs, Zy, Mx, Ms), which represent right and left symmetry in the maxillofacial structure, were selected. Statistically significant differences of the right and the left measurements were examined through t-test, and the difference of the right and the left measurement was compared among the six MSR planes. Results: The distances from the right and the left landmarks in each pair to each MSR plane did not show a statistically significant difference. The reproducibility of the landmark identification was excellent. Conclusion: All the six planes constructed in this study can be used as a MSR plane in maxillofacial 3D analysis, particularly, the planes including Cg and ANS.

• The korean journal of orthodontics
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• v.44 no.2
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• pp.77-87
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• 2014

Objectives: This study was designed to define the Korean norm values for the Ricketts analysis. Methods: In this longitudinal study, lateral cephalograms of 31 subjects with normal occlusion were taken biennially from ages 9-19 years. Cephalometric measurements were performed. Parameters for which the 10-year change did not exceed one standard deviation were defined as unchanged. The means and standard deviations for the measured parameters were determined for each age group. Results: No significant changes in growth were observed in the molar relationship, incisor overjet, incisor overbite, mandibular incisor extrusion, interincisor angle, lower incisor tip (B1) to A point-Pogonion (A-PO) plane, upper incisor tip (A1) to A-PO plane, B1 inclination to A-PO, A1 inclination to A-PO, B1 inclination to Frankfurt plane (FH), convexity, lower facial height, facial axis, maxillary depth, maxillary height, palatal plane to FH, cranial deflection, ramus Xi position, or porion location. Continual changes over the 10 years of growth were observed in the maxillary first molar distal position to pterygoid true vertical plane, facial depth, mandibular plane to FH, anterior cranial length, mandibular arc, and corpus length. Conclusions: Clinicians can apply the Korean norms at age 9 as determined in this study when using the Ricketts analysis. The patient's age at the beginning of treatment and their sex should be taken into consideration when drawing visual treatment objectives.

• The Journal of Advanced Prosthodontics
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• v.5 no.1
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• pp.58-66
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• 2013

PURPOSE. The purpose of this study was to decide the most appropriate point on tragus to be used as a reference point at time of marking ala tragus line while establishing occlusal plane. MATERIALS AND METHODS. The data was collected in two groups of subjects: 1) Dentulous 2) Edentulous group having sample size of 30 for each group with equal gender distribution (15 males, 15 females each). Downs analysis was used for base value. Lateral cephalographs were taken for all selected subjects. Three points were marked on tragus as Superior (S), Middle (M), and Inferior (I) and were joined with ala (A) of the nose to form ala-tragus lines. The angle formed by each line (SA plane, MA plane, IA plane) with Frankfort Horizontal (FH) plane was measured by using custom made device and modified protractor in all dentulous and edentulous subjects. Also, in dentulous subjects angle between Frankfort Horizontal plane and natural occlusal plane was measured. The measurements obtained were subjected to the following statistical tests; descriptive analysis, Student's unpaired t-test and Pearson's correlation coefficient. RESULTS. The results demonstrated, the mean angle COO (cant of occlusal plane) as $9.76^{\circ}$, inferior point on tragus had given the mean angular value of IFH [Angle between IA plane (plane formed by joining inferior point-I on tragus and ala of nose- A) and FH plane) as $10.40^{\circ}$ and $10.56^{\circ}$ in dentulous and edentulous subjects respectively which was the closest value to the angle COO and was comparable with the values of angle COO value in Downs analysis. Angulations of ala-tragus line marked from inferior point with occlusal plane in dentulous subject had given the smallest value $2.46^{\circ}$ which showed that this ala-tragus line was nearly parallel to occlusal plane. CONCLUSION. The inferior point marked on tragus is the most appropriate point for marking ala-tragus line.

• The korean journal of orthodontics
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• v.18 no.1 s.25
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• pp.253-265
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• 1988

This study was designed to compare the normal head posture group with the extended head posture group in order to investigate the relatinship between head posture and craniofacial morphology. The subjects were devided into two groups; one included 80 children with normal head posture and occlusion, and the other 60 malocclusion patients with extended head posture. Their lateral cephalograms were traced and analysed based on 38 selected items. The following conclusion were reached. 1. The craniocervical angulations in normal group; OPT to SN, CVT to SN, OPT to FH and CVT to FH angles were $101.7^{\circ},\;104.8^{\circ},\;91.7^{\circ}\;and\;100.7^{\circ}$, respectively. 2. Compared with normal group, experimental group showed increase in mandibular plane angle, decrease in facial plane angle, airway space and posterior facial height but, there were insignificant differences in anterior facial height and tongue level between two groups. 3. Of the craniocervical angulations, OPT to FH angle was most highly correlated to the variables of the craniofacial morphology. 4. The effect of craniocervical angulation on craniofacial morphology in experimental group was different from that in comparison of normal group and experimental group.

• The korean journal of orthodontics
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• v.39 no.5
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• pp.300-309
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• 2009

Objective: The purpose of this study was to evaluate the correlation between menton deviation and dental compensation in facial asymmetry. Methods: Tooth axis and distance of first molar and canine to the reference plane were investigated by cone-beam computerized tomography. The subjects consisted of 50 patients with asymmetric mandibles (male 21, female 29, mean age 24.3 years). Control groups were also assessed (male 11, female 9, mean age 25.6 years). Nine measurements (5 linear measurements and 4 angular measurements) were measured in order to evaluate the correlation between menton deviation and the linear and angular difference of first molar and canine in the deviated and none-deviated sides using the defined MPR images. The differences between deviated and non-deviated side, according to menton deviation, were statistically analyzed using stepwise multiple regression analysis. Results: From the result, Menton deviation was negatively correlated with mandibular first molar's angular measurement (${\Delta\angle}LM6$-Mn plane (dev.-ndev.)) and positively with maxillary fist molar's angular measurement (${\Delta\angle}UM6$-FH plane (dev.-ndev.)) (p < 0.01). Two angular measurements (${\Delta\angle}LM6$-Mn plane (dev.-ndev.), ${\Delta\angle}UM6$-FH plane (dev.-ndev.)) explained the variability in menton deviation with a significant $r^2$ value of 0.589. Conclusions: This study suggests that the tooth axis of upper and lower first molars leans towards the deviated side of Menton when there is mandibular asymmetry with Menton deviation.

• The korean journal of orthodontics
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• v.28 no.5 s.70
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• pp.791-802
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• 1998

The purpose of this study was to obtain the angulation and inclination of FACC of all teeth to FH plane. Study models of 31 persons with normal occlusion were selected and mounted on the semiadjustable articulator for this study. Using T.A.R.G. with a little modified method, the angulation and inclination of FACC of all teeth to FH plane were measured and then the measurements were analyzed statistically. The obtained results were as follows. Mean, standard deviation, maximum value, and minimum value of the angulation and inclination of FACC of upper and lower teeth were obtained. $\cdot$The FACC in both upper and lower arch was progressively lingually-inclined from anterior teeth to posterior teeth. $\cdot$In the angulations of FACC of upper teeth, central and lateral incisor showed similar value. Yet, the FACC of the rest was progressively distally-angulated from the canine to posterior teeth. The FACC in lower arch was progressively mesially-angulated from anterior teeth to posterior teeth. $\cdot$The angulation and inclination of FACC of any tooth in both upper and lower teeth correlated strongly and positively with the angulation and inclination of FACC of adjacent tooth.

• The korean journal of orthodontics
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• v.26 no.3
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• pp.267-279
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• 1996

This study was investigated the changes during treatment and retention period in the Class III malocclusion patients and explored the correlationship between factors that showed relapse tendencies and pre-treatment skeletal pattern and the changes during treatment period. Numbers of total sample were 24 and their Hellman's dental age at the start of treatment was over III B and were retained at least over 1 year 6 months. The following conclusion were obtained by comparing the differences between treatment period and retention period, and after analysing the correlationship of factors that manifested relapse tendencies. 1. The angles formed by FH plane and occlusal plane, FH plane and mandibular plane, and mandibular incisor and mandibular plane changes showed rebound effect during retention period and among them occlusal plane angle and IMPA show reverse correlationship. 2. Upward displacement of the occlusal plane at the end of treatment has returning tendency, is proportional to the displacement during treatment period, but the angle between maxillary and mandibular 1st molar to its basal bone have been constantlsy maintained during the retention period. 3. Mandibular plane decrease during retention period and downward backward rotation during treatment period show correlationship.

• The korean journal of orthodontics
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• v.6 no.1
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• pp.39-46
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• 1976

This study was undertaken to establish the cephalometric standards, using lateral cephalometric roentgenograms of 48 male and 53 female Korean adults with normal occlusion and acceptable profile. By Cohen's method, measurement of depth was taken parallel to the FH plane and expressed as a percentage of the cranial base depth (BA-N). And vertical height was measured along the line perpendicular to the FH plane and expressed as a percentage of the anterior face height (N-M). The following conclusions were obtained: 1) Means and standard deviations of craniofacial proportions of Korean adults were tabulated. 2) Cranial babe depth of male was greater than that of female. 3) The proportionate depth of the middle face was greater in female than in male. 4) The proportionate total anterior face height was greater in male than in female. And it was greater in Korean than in the white.

• The korean journal of orthodontics
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• v.31 no.4 s.87
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• pp.403-414
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• 2001

The purpose of this study was to evaluate treatment effects of the modified Teuscher appliance (MTA) in early Class II division 1 malocclusion. For this purpose, treatment effects of the bionator were compared with those of the MTA. The twenty subjects who were treated excellently with bionator and MTA were selected in each group. In pre- and post-treatment lateral cephalograms, 50 variables were measured, and then the differences between pretreatment and posttreatment data of the bionator and the MTA were statistically evaluated by t-test. The results were as follows : 1. The linear measurements that showed large difference between the bionator group and the MTA group are U1 to FH, U1 to PP, U6 to FH, U6 to PP, Ar-Pog, ramus height, L1 to A-Pog, L1 to facial plane (p<0.05). 2. The angular measurements that showed large difference between the bionator group and the MTA group are SNB, SNA, FABA, APDI (p<0.05). 3. The measurements of the growth pattern such as facial height ratio, FMA, SN-MP angle showed no difference between two groups (p>0.05). These results suggest that the bionator influence the mandiblar growth and lower dentoalveolar structures more than the MTA, and the MTA influence upper jaw and upper dentoalveolar structures more than the bionator comparatively in early Class II division I malocclusion.

• Imaging Science in Dentistry
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• v.34 no.1
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• pp.7-12
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• 2004

Purpose: To investigate the anatomical structure of the incisive canal radiographically by a cone beam computed tomography. Materials and Methods: 38 persons (male 26, female 12) were chosen to take images of maxillary anterior region in dental CT mode using a cone beam computed tomography. The tube voltage were 65, 67, and 70kVp, the tube current was 7 mA, and the exposure time was 13.3 seconds. The FH plane of each person was parallel to the floor. The images were analysed on the CRT display. Results: The mean length of incisive canal was 15.87 mm±2.92. The mean diameter at the side of palate and nasal fossa were 3.49 mm±0.76 and 3.89 mm± 1.06, respectively. In the cross-sectional shape of incisive canal, 50% were round, 34.2% were ovoid, and 15.8% were lobulated. 87% of incisive canal at the side of nasal fossa have one canal, 10.4% have two canals, and 2.6% have three canals, but these canals were merged into one canal in the middle portion of palate. The mean angles of the long axis of incisive canal and central incisor to the FH plane were 110.3°±6.96 and 117.45°±7.41, respectively. The angles of the long axis of incisive canal and central incisor to the FH plane were least correlated (r= 0.258). Conclusion : This experiment suggests that a cone beam computed radiography will be helpful in surgery or implantation on the maxillary incisive area.