IRUCAA@TDC : A study of the changes in facial profile after orthodontic treatment. Part 1. Comparison between the improved group and unimproved group

全文

(1)Title. Author(s) Journal URL. A study of the changes in facial profile after orthodontic treatment. Part 1. Comparison between the improved group and unimproved group Tochikura, M; Nomura, M; Konishi, H; Suzuki, T; Sebata, M; Isshiki, Y Bulletin of Tokyo Dental College, 40(1): 7-20 http://hdl.handle.net/10130/1016. Right. Posted at the Institutional Resources for Unique Collection and Academic Archives at Tokyo Dental College, Available from http://ir.tdc.ac.jp/.

(2) Bull. Tokyo dent. Coll., Vol. 40, No. 1, pp. 7⬃20, February 1999. Original Article. A STUDY OF THE CHANGES IN FACIAL PROFILE AFTER ORTHODONTIC TREATMENT PART 1. COMPARISON BETWEEN THE IMPROVED PART 1. GROUP AND UNIMPROVED GROUP MAYUMI TOCHIKURA, MAYUMI NOMURA, HARUMI KONISHI, TOSHIMASA SUZUKI, MASAYUKI SEBATA and YASUSHIGE ISSHIKI Department of Orthodontics, Tokyo Dental College, 1-2-2 Masago, Mihama-ku, Chiba 261-8502, Japan. Received 6 November, 1998/Accepted for Publication 9 December, 1998. Abstract The purpose of this study was to investigate the harmonious facial profile before and after orthodontic treatment on permanent dentition and to determine the factors which influence lateral facial harmony. Materials were lateral Roentgen cephalograms from 150 subjects (25 males and 25 females each in 3 groups— maxillary protrusion, mandibular protrusion and crowding—) taken before and after treatment. The average age before treatment was 11 years and 6 months and, after treatment, was 14 years and 3 months. The term of active treatment was 2 years and 9 months. Lateral facial evaluation based on the external profile line was performed by a group of 40 persons which included dental students and the general public. In the 5 stage evaluation, each subject could receive from 40 to 200 points. The subjects with more than 121 points were classified in the harmonious group; those with less than 120 points were classified in the disharmonious group. Subjects who had been classified as disharmonious before treatment but became harmonious after treatment constituted the improved group. Subjects classified disharmonious before treatment who remained disharmonious after treatment constituted the unimproved group. The value of the overall harmonious group before treatment was 8.6% and, after treatment, was 36.6%. The increase in the percentage of cases classified as harmonious varied among the different occlusal types: for the mandibular protrusion, the value before treatment was 2% and after treatment was 32%, for crowding it was 18% before and 46% after treatment, and for maxillary protrusion, it was 6% before and 32% after treatment. The ratio of percentage in the harmonious group increased on every malocclusion group after treatment, suggesting the importance of orthodontic treatment for improvement of lateral facial harmony. Before treatment, the morphological conditions in the improved group were more advantageous than those in the unimproved group. Key words:. The harmonious facial profile—Roentgen cephalogram — Effect of orthodontic treatment— Changes of facial profile — External profile line. This study is part of a dissertation submitted by Mayumi Tochikura to Graduate School of Tokyo Dental College for the degree of Doctor of Philosophy. Shikwa Gakuho (95, 53–93, 1995).. 7.

(3) 8. M. TOCHIKURA et al.. INTRODUCTION Edward H. Angle1) suggested that one of the major purposes of orthodontic treatment is facial harmony. Therefore, orthodontic treatment plays a very important role in improving malocclusion and facial disharmony. Investigation of the changes between the harmonious facial profile before and after orthodontic treatment is very important for the evaluation of treatment effects, possibilities, and predictions. Evaluation of facial esthetics varies from person to person, and orthodontic studies have reported that the evaluation may vary depending on age, sex, or orthodontic knowledge4). There are many methods using profile lines9), facial photographs7,12,13) and or people by themselves18). In order to judge the results of orthodontic treatment, dental plaster models or cephalograms are used10,15,17). For this study, we used lateral cephalograms taken before and after treatment. The purpose of this study was to investigate the harmonious facial profile before and after orthodontic treatment on permanent dentition in 3 groups, maxillary protrusion, mandibular protrusion, and crowding, and to determine the factors which influence the harmonious facial profile.. of Orthodontics of the Tokyo Dental College. The selected patients were successfully in treated cases which had been evaluated as “Good” or “Satisfactory” by Gottlieb’s grading analysis5). The average age before treatment was 11 years and 6 months (minimum 8y7m– maximum 15y8m) and that after treatment was 14 years and 3 months (min. 11y2m–max. 17y8m); active treatment was 2 years and 9 months. Lateral cephalograms of these subjects (which were taken in centric occlusion) were used in this study. 2. Method of evaluation Evaluators were 40 persons divided in to two groups (each group consisted of 10 males and 10 females). One group was composed of students from Tokyo Dental College who had orthodontic knowledge. The average age was 24 years and 5 months. The other group was composed of members of the general public. MATERIALS AND METHODS 1. Materials One hundred and fifty subjects were selected from three groups of malocclusion (each group consisted of 25 males and 25 females): mandibular protrusion, maxillary protrusion, and crowding. The selection criteria were: maxillary protrusion cases with an overjet of more than 5 mm, mandibular protrusion cases with a continuous cross bite that includes more than 3 incisors (both central incisors and one lateral) and crowding cases with discrepancies of more than 5 mm in both upper and lower dentition. Patients were treated by multi bracket appliances using the edgewise method at the Department. Fig. 1 Samples of external profile lines A: Before treatment, B: After treatment.

(4) 9. LATERAL FACIAL CHANGE PART 1. Skeletal P. 1 Saddle angle 2 Cranial l. ant 3 Porion loc. 4 SNA 5 NA-FH 6 Convexity 7 Convexity 8 Palatal pl. 9 SNB 10 NB-FH 11 Facial angle 12 Gonial angle 13 Mandibular arc 14 Mandibular pl. 15 Ramus angle 16 S-Ar-Go 17 Ramus posit. 18 Y-axis 19 Facial axis 20 Corpus l. 21 ANB 22 A-B pl. 23 Wits 24 Total facial ht. 25 Lower facial ht. 26 Post facial ht. 27 FH-SN. Fig. 2 Cephalometric measurements of hard tissue. (mm). (mm) (mm) (mm). Denture P. 28 U1 to FH 29 U1 to A-Pog (mm) 30 L1 to FH 31 L1 to Occlusal pl. 32 L1 to Mandibular pl. 33 L1 to A-Pog 34 L1 to A-Pog (mm) 35 Interincisal angle 36 Occlusal pl. 37 Overjet (mm) 38 Overbite (mm). Soft tissue 1 NFR 2 NFA 3 Prn-Pogs-Sn 4 G-Sn to FH 5 G-Sn-P 6 Sn-P to FH 7 Sn-Ls1 to FH 8 Nasolabial angle 9 ULip to E pl. 10 Pogs-Li to FH 11 Prn-Pogs-Li 12 LLip to E pl. 13 G-Pogs to FH 14 Gns-P to FH 15 G-Sn to Sn-Pogs 16 G-Sn to Sn-Bs 17 NM 18 Ns-Sn/Ns-Mes 19 Sn-Mes/Ns-Mes 20 Stm-Mes/Sn-Stm 21 Prn-Pogs to FH 22 P-Sn-Pogs 23 Sn-Ls1 to Pogs-Li 24 Ns-Sn 25 Sn-Stm 26 Stm-Mes 27 Ns-Mes 28 Sn-Mes. Fig. 3 Cephalometric measurements of soft tissue. (mm) (mm). Thickness of soft tissue 1 N-Ns 2 Ans-Prn 3 A-Sn 4 U1e-Ls2 5 L1e-Li 6 B-Bs 7 Pog-Pogs. (mm) (mm). (%) (%) (%). (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm).

(5) 10. M. TOCHIKURA et al. Table 1-1 The percentage of harmonious group by lateral facial evaluation Before treatment Malocclusion type Maxillary protrusion Mandibular protrusion Crowding Total. After treatment. H No. (%). D No. (%). H No. (%). D No. (%). 3 ( 6) 1 ( 2) 9 (18). 47 (94) 49 (98) 41 (82). 16 (32) 16 (32) 23 (46). 34 (68) 34 (68) 27 (44). 13 ( 8.6). 137 (91.4). 55 (36.6). 95 (63.4). H: Harmonious group, D: Disharmonious group Table 1-2 Changes in lateral facial evaluation before and after orthodontic treatment Malocclusion type. Maxillary protrusion. Mandibular protrusion. Crowding. Total. Before treatment No. (%) H. 3 ( 6). D. 47 (94). H. 1 ( 2). D. 49 (98). H. 9 (18). D. 41 (82). H. 13 ( 8.6). D. 137 (91.4). After treatment No. (%) H D H D. 2 1 14 33. (66.7) (33.3) (29.8) (70.2). H D H D. 1 0 15 34. (100) ( 0) (30.6) (69.4). H D H D. 6 3 17 24. (66.7) (33.3) (41.5) (58.5). H D H D. 9 4 46 91. (69.2) (30.8) (33.6) (66.4). H: Harmonious group, D: Disharmonious group. who had no orthodontic knowledge. Their mean age was 38 years and 3 months. Traces of external profile line included the Frankfort horizontal plane (Fig. 1), and the patient’s gender was described. Materials were arranged randomly within malocclusion types but segregated on the bases of before and after treatment. Evaluators judged each subject on a 5 grade scale: 5 (good), 4 (satisfactory), 3 (mediocre), 2 (poor), 1 (unsatisfactory). Those receiving more than 121 points were classified in the harmonious group; those receiving less than 120 points were classified in the disharmonious group (evaluators judged each group. before and after treatment). 3. Analysis of cephalograms 1) Landmarks In this study, the 46 landmarks included 28 for hard tissue and 18 for soft tissue. 2) Cephalometric measurement items Hard tissue measurement items (1–38) are shown in Fig. 2. Soft tissue measurement items (1–28) and soft tissue thicknesses (1–7) are shown in Fig. 3. These measurements were selected from Downs’, N-W, Ricketts’, Sebata’s and Nomura’s analyses3)6)8)9)10). 3) Instruments Cephalometric measurement values were.

(6) LATERAL FACIAL CHANGE PART 1. 11. Table 2-1 Results of hard tissue measurements in the improved and unimproved groups with maxillary protrusion. Significant level: * 5%, ** 1%, *** 0.1%, Paired t -test: before and after treatment. processed by the cephalogram analysis program Versa-STAT (Yasunaga Laboratories). These data was transferred to a personal computer (NEC PC 9801) with a digitizer, and the data was saved on a floppy disk. 4) Statistics In order to investigate the relationship between evaluated changes before and after orthodontic treatment and cephalometric measurements from the 3 groups of malocclusions, those evaluated as disharmo-. nious before treatment were further divided into 2 groups. One group, called the improved group, became harmonious after treatment, and the other group, called the unimproved group, remained disharmonious after treatment. These groups were composed before and after treatment. Statistical analysis was performed by means of the SPSS program. Means and standard deviations of cephalometric measurements of.

(7) 12. M. TOCHIKURA et al. Table 2-2 Results of soft tissue measurements in the improved and unimproved groups with maxillary protrusion. Significant level: * 5%, ** 1%, *** 0.1%, Paired t -test: before and after treatment. both groups were calculated using the t-test. Analysis of variance (ANOVA) was used to analyze the 3 groups, and Schffe’s method16) of multiple comparison was applied.. RESULTS 1. Changes in lateral facial evaluation points before and after treatment Before treatment, the percentages of the harmonious group by lateral facial evaluation were 6% in the maxillary protrusion group,. 2% in the mandibular protrusion group, and 18% in the crowding group; the combined value was 8.6%. After treatment, it was 32% in the maxillary protrusion group, 32% in the mandibular protrusion group, 46% in the crowding group, and 36.6% in the combined groups (Table 1-1). Thus the percentage in the harmonious group increased after treatment. A summary of changes in the evaluation points before and after treatment in all subjects were as follows (Table 1-2): of 13 patients who were evaluated as harmonious be-.

(8) LATERAL FACIAL CHANGE PART 1. 13. Table 3-1 Results of hard tissue measurements in the improved and unimproved groups with mandibular protrusion. Significant level: * 5%, ** 1%, *** 0.1%, Paired t -test: before and after treatment. fore treatment, 9 patients (69.2%) remained harmonious after treatment, but 4 (30.8%) became disharmonious after treatment. among 137 patients who were evaluated as disharmonious before treatment, 46 patients (33.6%) improved and became harmonious after treatment, while 91 patients (66.4%) remained disharmonious after treatment. The size of the harmonious group increased after treatment; however, 4 patients decreased with regard to evaluation points.. 2. Results of descriptive statistics 1) Changes between the improved group and the unimproved group The results of descriptive statistics between the two groups were classified based on lateral facial evaluation points. Tables 2-1, 2-2, 3-1, 3-2, 4-1, and 4-2 compare the improved and unimproved groups, before and after treatment. Tables 5-1 and 5-2 compare before and after treatment in the improved group and unimproved groups..

(9) 14. M. TOCHIKURA et al. Table 3-2 Results of soft tissue measurements in the improved and unimproved groups with mandibular protrusion. Significant level: * 5%, ** 1%, *** 0.1%, Paired t -test: before and after treatment. (1) Maxillary protrusion (Table 2-1, Table 2-2, Table 5-1, Table 5-2) The improved group had the following characteristics as compared with the unimproved group. Before treatment, the mandibular arc and pogonion rotated forward, the lower facial height and total facial height were small, the upper and lower incisor edges were retruded, the lower incisors tipped lingually, and the thickness of soft point B was thin. After treatment, the improved group showed significant differences in the following measurements: overjet and nasal height became smaller, upper and lower lip were. retruded, pogonion grew forward, and the lower facial height became smaller than the mid-facial height. Although the lower facial height and thickness of soft point B differed from measurements obtained before treatment, these differences were not significant. The improved group showed significant differences in the changes in overjet and nasal height, which both became smaller after treatment. (2) Mandibular protrusion (Table 3-1, Table 3 -2, Table 5-1, Table 5-2) The improved group had the following characteristics when compared with the.

(10) LATERAL FACIAL CHANGE PART 1. 15. Table 4-1 Results of hard tissue measurements in the improved and unimproved groups with crowding. Significant level: * 5%, ** 1%, *** 0.1%, Paired t -test: before and after treatment. unimproved group. Before treatment, porion, point B and mandibular arc were placed backward, lower incisors tipped labially, overjet and overbite were small, nasal height was shorter than mid lower face, upper lip tipped lingually and the upper and lower lips were thin. After treatment, most of the above mentioned items improved except for the tips of the lower incisors and the thickness of the lower lip. However, the following items were noted only after treatment in the im-. provement group; point A was located in front of the facial plane, ANB was positive, and the lower facial height was smaller than the mid-facial height. In the unimproved group point A was located in back of the facial plane and ANB was negative. Improvement included the following factors:—point A placed forward, the mandibular plane inclined upward and forward, and the overjet became larger than in the unimproved group..

(11) 16. M. TOCHIKURA et al. Table 4-2 Results of soft tissue measurements in the improved and unimproved groups with crowding. Significant level: * 5%, ** 1%, *** 0.1%, Paired t -test: before and after treatment. (3) Crowding (Table 4-1, Table 4-2, Table 5-1, Table 5-2) The improved group had the following characteristics when compared with the unimproved group: before treatment, the student’s t-test did not detect significant difference in hard tissues variables. In measurement of soft tissues, the upper and lower facial height decreased in the improved group. After treatment, the improved group shown significant differences in the following variables: upper and lower incisal edge were retracted, lower incisors tipped lingually, subnasion placed forward against. the glabella, mid-lower facial height became smaller than total facial height and thickness of soft point A became thin. The lower facial height became smaller and thickness of soft point B became thin in the improved group. 2) Analysis of variance for three malocclusion groups Analysis of variance was applied to test the three malocclusion groups before treatment, after treatment, and to compare them between before and after treatment. The comparison between the maxillary protrusion group and crowding group after treatment.

(12) LATERAL FACIAL CHANGE PART 1. Table 5-1 Variables indicating significant differences between improved and unimproved groups: hard tissue measurements. Significant level: * 5%, ** 1%, *** 0.1%, Unpaired t -test A: Before treatment, B: After treatment, C: Treatment change Table 5-2 Variables indicating significant differences between improved and unimproved groups: soft tissue measurements. Significant level: * 5%, ** 1%, *** 0.1%, Unpaired t -test A: Before treatment, B: After treatment, C: Treatment change. 17.

(13) 18. M. TOCHIKURA et al. Table 6 Results of ANOVA: after treatment Group. A vs. B. B vs. C. 1. G-Sn to Sn-Pogs ( ° ). ⬎⬎. ⬍⬍. 2. G-Sn to Sn-Bs. ( ° ). ⬎⬎. ⬍⬍. 3. NFR. ( ° ). 4. NFA. ( ° ). 5. Prn-Pogs-Sn. ( ° ). ⬍⬍. ⬎. 6. NM. ( ° ). ⬍⬍. ⬎⬎. Direction of pogonion growth. 7. G-Pogs to FH. ( ° ). ⬍⬍. ⬎⬎. U lip protrusion. 8. U Lip to E-pl.. (mm). ⬎. L lip protrusion. 9. L Lip to E-pl.. (mm). Variables Facial type. Nasal height. A vs. C. ⬎. Significant level: ⬎5%, ⬎⬎1% A: Maxillary protrusion, B: Mandibular protrusion, C: Crowding. showed similar forms of soft tissues. However, comparison between other pairs showed significant differences (Table 6). These results suggested that, before treatment, the lateral facial profile on in mandibular protrusion group was different from those of the maxillary protrusion and crowding groups. After treatment, the maxillary protrusion and crowding groups had similar lateral facial profiles.. DISCUSSION 1. Method of evaluation Evaluations of facial esthetics could be influenced by the level of orthodontic knowledge, sex, or age of the evaluator. Evaluators have different opinions and individual preferences. Dongieux and Sassouni2) found no difference between orthodontists, students, and artists in their esthetics preferences. On the other hand, Foster4) maintained that orthodontists showed different esthetics preferences from others (general dentists, art students, black people, Chinese people, and Caucasians) in evaluations of adult males and females. These studies suggested the necessity of balance in the persons selected as evaluators.. Thus, in the present study, we selected 40 evaluators who were divided into 2 groups composed of the same number of males and females. One group had orthodontic knowledge, and the other did not. Evaluators judged trace of external profile lines and materials arranged randomly in relation to malocclusion type and before and after treatment. 2. Results 1) Changes in lateral facial evaluation points before and after orthodontic treatment We could not find any literature which compared lateral facial harmony observed before and after orthodontic treatment. However, studies comparing the lateral facial harmony between three types of malocclusion have been reported7,13,14,18). Those studies stated that most subjects in the harmonious group had class I occlusion. Yamauchi18) reported that female subjects in the harmonious group tended to have class II malocclusion. Patients with all types of malocclusion could achieve harmonious facial profiles with orthodontic treatment. In this study, we evaluated lateral facial profiles before and after orthodontic treatment for three types of malocclusion: crowding,.

(14) 19. LATERAL FACIAL CHANGE PART 1. maxillary protrusion, and mandibular protrusion. The results obtained by Yamauchi18) were difficult to compare with the results obtained in this study, owing to differences in the subject selection methods used. There was some agreement with regard to the fact that some malocclusion types were included in the harmonious group. According to Ito et al.7) 36 out of 43 patients were classified as harmonious after orthodontic treatment; their percentage of harmonious group was very high compared with our results (36.6%). However, the ratios of malocclusion types in our study differs from those in Ito et al. study, so the results can not be easily compared. On the other hand, Sebata et al.13) reported results very similar to ours with regard to classification of malocclusion type and the number of subjects with each type of malocclusion. Sebata et al.14) found that, 37% of all malocclusion subjects were classified as harmonious. This percentage was very high compared with our result (8.6%). We agree with Sebata et al.14) with regard to the malocclusion ratio of the harmonious and crowding groups. However, our maxillary protrusion group and mandibular protrusion group differed from theirs. These disagreements in lateral facial evaluation might be due to differences in the material selected. In our study, the external profile line were used as the data source, while Yamauchi18) evaluated people themselves, and Ito et al.7) and Sebata et al.13) judged the esthetic profile by lateral facial photographs. In this study the changes observed before and after orthodontic treatment, were as follows: before treatment, the overall percentage of the harmonious group was only 8.6%, but, after treatment, it increased to 36.6%. Furthermore, the ratio of the harmonious group increased on every malocclusion group after treatment. These results confirmed the importance of orthodontic treatment in the improvement of harmonious facial profile. 2) Differences between the improved group and unimproved groups Many past studies have reported methods for judgment of lateral facial harmony and. disharmony. Most of these studies have based judgment on skeletal classification involving lateral facial type (convex type or concave type) or lower facial form around lips. Yamauchi18) and Riedel11) reported that the harmonious facial profile involved retaction of the pogonion and lingual tipping of upper incisors. Tweed17) reported the importance of lower incisal position (L1 to Mandibular pl. was 90°5°), and our study showed similar results with regard to improvement after treatment. Sebata14) reported that the harmonious facial profile was related to the ANB angle and the lower incisal angle. Thus, they shared the opinion that the shape of lip was a very important factor in the harmonious facial profile. In this study, we investigated the factors which influenced the harmonious facial profile. In our comparison of three groups of malocclusion, we found the factors involved in harmonious facial profile included the following. In the hard tissue measurements, the difference in the anterior-posterior relationship of the maxilla and mandible was small, and the position of upper and lower incisors was retruded. In the soft tissue measurements, the upper and lower lips were retruded, the lower lip was thin, and the ratio of the height of the lower face was decreased. Finally, the improved group had more advantageous morphological conditions than the unimproved group before treatment. Also, skeletal balance is preferable to a harmonious facial profile. However, in case of slight skeletal unbalance, the skeletal problems can be improved by of orthodontic tooth movement, thus achieving a harmonious facial profile and soft tissue balance. The fact that the ratio of the harmonious group increased in every malocclusion group after treatment suggested the importance of orthodontic treatment for the harmonious facial profile.. REFERENCES 1) Angle, E.H. (1900). The Treatment of Maloc-.

(15) 20. 2). 3) 4) 5) 6) 7). 8). 9). 10) 11). M. TOCHIKURA et al. clusion of the Teeth and Fractures of the Maxillae. 6th ed., pp.5–23, S.S. White Dental Manufacturing Co., Philadelphia. Dongieux, J. and Sassouni, V. (1980). The contribution of mandibular positioned variation to facial esthetics. Angle Orthod 50, 334– 339. Downs, W.B. (1956). Analysis of the dentofacial profile. Angle Orthod 26, 191–212. Foster, E.J. (1973). Profile preference among diversified groups. Angle Orthod 43, 34–40. Gottlieb, E. (1975). Grading your orthodontic treatment results. J of Clin Orthod 9, 155– 161. Graber, T.M. (1952). New horizons in case analysis— Clinical cephalometrics. Am J Orthod 38, 603–624. Ito, K., Ueki, S., Tabe, T. and Yamauchi, K. (1977). A consideration with stabilized position of incisors after orthodontic treatment. Journal of Japan Orthodontic Society 36, 212–230. (in Japanese) Nezu, H., Nagata, K., Yoshida, Y. and Kikuchi, K. (1984). Bioprogressive Diagnosis, 1st. pp.45–54, Rocky Mountain Morita, Tokyo. (in Japanese) Nomura, M. (1988). A study of the harmonious profile in facial esthetics—On the normal occlusion and that after orthodontic treatment. Shikwa Gakuho 88, 1557–1602. (in Japanese) Ricketts, R.M. (1960). A foundation for cephalometric communication. Am J Orthod 46, 330–357. Riedel, R.A. (1957). An analysis of dentofacial relationships. Am J Orthod 43, 103–119.. 12) Sebata, M., Kikuchi, M., Nogami, K., Harazaki, M. and Ichimura, K. (1969). Studies for establishing basis of construction of harmonious profile of Japanese–1 –. Journal of Japan Orthodontic Society 28, 61–67. (in Japanese) 13) Sebata, M., Kikuchi, M., Nogami, K., Harazaki, M. and Ichimura, K. (1969). Studies for establishing basis of construction of harmonious profile of Japanese–2 –. Journal of Japan Orthodontic Society 28, 239–253. (in Japanese) 14) Sebata, M. (1973). Orthodontic treatment and harmony of facial profile. Shikwa Gakuho 73, 617–628. (in Japanese) 15) Steiner, C.C. (1960). The use of cephalometrics as an aid to planning and assessing orthodontic treatment. Am J Orthod 46, 721– 735. 16) Tsunami, K. and Origasa, H. (1995). Medical Uses of Scientics, 1st ed., pp.180–182, Scientist Co., Tokyo. (in Japanese) 17) Tweed, C.H. (1946). The frankfort— mandibular plane angle in orthodontic diagnosis classification, treatment planning, and prognosis. Am J Orthod 32, 175–230. 18) Yamauchi, K. (1962). Studies on “beautiful face” of Japanese female adult. Part 1 Roentgen-Cephalometric analysis. Journal of the Osaka University Dental Society 6, 99–116. (in Japanese) Reprint requests to: Dr. Mayumi Tochikura Department of Orthodontics, Tokyo Dental College, 1-2-2, Masago, Mihama-ku, Chiba 261-8502, Japan.

(16)