• The korean journal of orthodontics
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• v.25 no.3 s.50
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• pp.355-373
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• 1995

Craniofacial region is a musculodentoskeletal system that consists of many anatomical structures ; cranioskeletal structures, dental arches, and formation and functions of masticatory muscles have close correlations. Growth and development of craniofacial region are influenced by not only hereditory factors, but also environmental factors such as craniofacial muscles and surrounding tissues. On the contrary, however, study on changes in functions or adaptations of craniofacial muscles following changes of craniofacial skeletal structures has been somewhat insufficient. The author's purpose was to observe correlations between masticatory muscular functions and change patterns according to cranial skeletal structures and occlusion patterns, for this, comparative study of muscle activity changes of preand post- orthognathic surgery states in skeletal Cl III malocclusion patients was peformed. The selected sample groups were 15 normal male patients, 15 skeletal Cl III pre-orthognatic surgery patients and 15 skeletal Cl III post-orthognatic surgery patients. For each sample groups, cephalometric x-ray taking, masticatory efficiency test and measurements of muscle activities in anterior temporal muscle, masseter and upper lip in rest, clenching, chewing and swallowing were carried out. The following results were obtained : 1. In resting state of mandible, pre-surgery malocclusion group showed higher m. activities in ant. temporalis, masseter and upper lip than post-surgery group. Post-surg. malocc. group showed significantly high m. activity only in upper lip compared to the normal group. 2. In clenching state, post-surg. malocc. group showed higher m. activities in ut. temporalis, masseter and upper lip than pre-surg. malocc. group. 3. In chewing state, post-surg. malocc. group showed higher m. activities in ant. temporalis and masseter than pre-surg. malocc. group, on the other hand, decreased upper lip activity was noticed. 4. In swallowing state, post-surg. malocc. group showed lower upper lip activity than pre-surg. malocc. group but higher than that of the normal group. No significant difference in m. activities of ant, temporalis and masseter was noticed among the three groups. 5. Masticatory efficiency was lower in pre-surg. malocc. group than normal group, masticatory efficiency showed an increase in post-surg. malocc. group compared to the pre-surg. malocc. group. However, both groups showed significant differences compared to the normal group.

• The korean journal of orthodontics
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• v.28 no.2 s.67
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• pp.237-253
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• 1998

Surgical-orthodontic treatment is performed for the skeletal Class III patients with no remaining growth and too big a skeletal discrepancy (or camouflage treatment, and two jaw surgery is needed in order to have maximum effect in such patients. In two jaw surgery cases, surgical alteration of the occlusal plane is necessary to establish optimal function, esthetics and postoperative sability, therefore the establishment of the occlusal plane is essential in diagnosis and treatment. The object of this study is to evaluate the stability of the indiviual ideal occlusal plane bsaed on the architectural and structural craniofacial analysis of Delaires. Thus, the subjects of this study were 48 patients who underwent two jaw surgery, and divided in two groups. Each group were composed of 24patients, A group were operated with ideal occlusal plane and B group were not. Two groups were compared at the preoperative, immediate postoperative (average 4.3days), and long-term postoperative (average 1.3years) lateral cephalometric radiographs. The following results were obtained: 1. There was no significance in occlusal plane angulation between $T_2\;and\;T_3$. Average long term follow-up changes of occlusal Plane angle were $0.24^{\circ}{\pm}2.43$, with FH plane and $0.15{\circ}{\pm}2.16{\circ}$ with SN plane in all 48 patients. These results demonstrated that the occlusal plane after two jaw surgery in skeletal Class III malocclusion was stable. 2. There was no significance in postoperative stability of occlusal plane between A and B group. 3. There was no significance in postoperative stability of occlusal plane depending on surgeon and operative method within each group. 4. The postoperative changes of occlusal plane were correlated to the postoperative changes of jaw rather than tooth position. 5. There was no correlation between the postoperative changes of occlusal plane and maxillary impaction and mandibular setback with surgery.

• The korean journal of orthodontics
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• v.30 no.3 s.80
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• pp.367-375
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• 2000

If a mandibular prognathic patient has an extremely unnatural anteroposterior and vertical maxilla or keen esthetical perception for facial profile, orthognathic surgery must be performed along with orthodontic treatment, which alone cannot provide satisfactory results in this case. Esthetical improvement becomes an important factor in the satisfaction level of the patient's treatment result, but an attempt to objectively measure beauty holds many problems. Therefore, in the end, the patient submits the final esthetical evaluation based on his/her subjective viewpoint. Because Korean people have a tendency to prefer the facial appeareance of westerners, they favor an oval shaped face over the traditional round face. This research was conducted in response to the complaints raised by patients who claim that their face had become more round from widening of facial width after the orthognathic surgery for manidibular prognathism than before the surgery. The following results were obtained on the changes in facial appearance and patient satisfaction level by analyzing the skull P-A analysis of total of 14 patients (8 male and 6 female) who underwent orthognathic surgery primarily chief complaint for manidibular prognathism and from their responses on questionnaires. These results are to be used in the research on the pre- and post- operative changes in facial height and width from orthognatic surgery. 1. Three ($21.4\%$) of 14 patients said that their face had widened. 2. The A group showed no change in mandibular width but B group showed a 0.7mm reduction. The facial width increased by 0.45mm and 0.66mm in groups A and B, respectively, after the orthognathic surgery 3. After the surgery the facial length changed by an 0.52mm increase in upper facial height , 1.19mm reduction in lower facial height, and 0.7mm reduction in mandibular height in group A. In group B group, there was a 0.67mm reduction in upper facial height, 3.66mm reduction in lower facial height, and 5mm reduction in mandibular height. 4. In reference to facial width, the facial height showed $1.5\%$ reduction in group A and $3.6\%$ reduction in group B after the surgery. 5. In reference mandibular height-to-facial width ratio, there was a $1.3\%$ reduction in group A, and $4.4\%$ reduction in group B after the surgery. 6. In reference to the mandibular height-to-width ratio, there was a $1.3\%$ reduction in group A and $4.3\%$ reduction in group B after the surgery. 7. Although the change in the facial width due to surgery can be ignored, sufficient explanation should be Provided to the patient before surgery on the fact that the face can appear to be relatively wide because of the reduced facial length as result of the surgery.

• The korean journal of orthodontics
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• v.25 no.3 s.50
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• pp.311-321
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• 1995

This study was undertaken to investigate the distribution of the chewing side preference and variations in the maximum bite force and facial morphology according to chewing side preference since unilateral chewing may cause morphologic and functional anomalies. 50 dental students who had no signs or symptoms of masticatory system and Angle's Class I relationship in posterior segments were selected, and divided into two groups, that is, 25 in bilateral chewing group(19 male and 6 female) and 25 in unilateral chewing group(10 male and 15 female). Maximum bite force was estimated ana posteroanterior cephalogram were measured ana statistically analyzed. The results were as follows : 1. Their were more students with bilateral chewing side preference($68\%$) and unilateral chewing side group consisted of right side preference($68\%$) and left side preference($32\%$). 2. There was no significant difference in the strength of max. bite force between the right and left side in bilateral chewing group. The bite force of the chewing side nab greater in the unilateral chewing group but less in the non-chewing side compared to those of bilateral chewing group with Bo significant difference. Max. bite force of chewing side was greater than that of non-chewing side in the unilateral chewing group(Female p<0.05). Max. bite force of males was about twice in that of females in both groups(p<0.05). Max. bite force of chewing side of the unilateral chewing group was similar to that of the bilateral chewing group, but that of non-chewing side was less than that of the bilateral chewing group. 3. In comparison of the facial morphology, there was no statistically significant difference in the size between the right and left side of the bilateral chewing group and between chewing and non-chewing side of the unilateral chewing group.

• The korean journal of orthodontics
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• v.26 no.1 s.54
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• pp.1-16
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• 1996

The purpose of this study was to evaluate the amount and interrelationship of the soft and hard tissue changes after simultaneous maxillary advancement and mandibular setback surgery in skeletal Class III malocclusion. The sample consisted of 25 adult patients(13 males and 12 females) who had severe anteroposterior skeletal discrepancy. These patients had received presurgical orthodontic treatment and surgical treatment which consisted of simultaneous Le Fort I or Le Fort II osteotomy and bilateral sagittal split ramus osteotomy. The presurgical and postsurgical lateral cephalograms were evaluated. The computerized statistical analysis was carried out with SPSS/$PC^+$ program. The results were as follows. 1. The correlation of maxillary hard and soft tissue horizontal changes were high and the ratios for soft tissue to A point were $71\%$ at Sn, $67\%$ at SLS and $37\%$ at LS. 2. The correlation of mandibular hard and soft tissue horizontal changes were very high and the ratios were $84\%$ at LI, $107\%$ at ILS, $96\%$ at Pog' and $97\%$ at Gn'. 3. The correlation of mandibular hard tissue horizontal changes and soft tissue vertical changes were moderate. 4. The upper to lower lip length were increased(P<0.001). 5. The soft tissue thickness were decreased in upper lip and increased in lower lip(P<0.001). The postsurgical changes were reversely correlated with initial thickness in upper lip.

• The korean journal of orthodontics
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• v.33 no.4 s.99
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• pp.293-305
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• 2003

The pharynx have significant locations and functions because it forms a part of the unit in which respiration and deglutition are carried out. Because of the closed relationship between the pharynx and the dentofacial and craniofacial structure, many studies are carried out on this subjects. The purpose of this study were to compare the airway size including pharynx, soft palate, tongue and hyoid bone between normal and hyperdivergent skeletal pattern and to evaluate the change of those size in different age. The sample of this study were consisted of 51 subjects in normal group, 52 subjects in hyperdivergent group. Each was divided into two subgroups by age , child group(9-l2yr old) and adult group(18yr old over). The lateral cephalometric radiographs were taken and the distance, angle and ratio of the facial skeleton, pharynx, soft palate, tongue and hyoid bone were measured and evaluated statistically. The result obtained were summarized as follows : 1 SN-Mn angle, FMA, and Pal-Mn angle were significantly larger in child group than adult group, but the lower anterior facial height(LAFH) and facial height ratio(FHR) were significantly smaller in child group than adult group. Occlu-Mn angle was significantly steep in hyperdivergent group than normal, but not significantly different between child group and adult group. 2. Hyperdivergent group and child group had the stronger correlation between SN-Mn angle, FMA, Pal-Mn angle, LAFH and FHR and airway size than normal group and adult group. Hyperdivevgent child group had significant negative correlation between SN-Mn angle, FMA, Pal-Mn angle and sagittal skeletal dimension of nasopharynx and sagittal depth of nasopharyngeal lumen. Significant positive correlation were seen between LAFH and vertical measurement of airway. 3. There was no difference of the linear measurement of airway size between hyperdivergent group and normal group. 4. Adult group had smaller posterior pharyngeal wall, target nasopharyngeal depth longer nasopharyngeal height and longer pharyngeal length than child group. 5. The sagittal measurement of hyoid bone had no difference between child group and adult group. But adult group had larger vertical measurement of hyoid bone than child group.

• The korean journal of orthodontics
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• v.38 no.2
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• pp.104-120
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• 2008

Purpose: The purpose of this study was to assess the hard and soft tissue changes associated with mandibular bilateral sagittal split osteotomy and genioplasty. Methods: This is a retrospective study of 40 patients who underwent either bilateral sagittal split osteotomy for mandibular setback (BSSO group, n = 20) or in combination with advancement genioplasty (Genio group, n = 20). Lateral radiographs, were taken before and immediately after surgery, and at least 6 months after surgery. Results: Comparing hard and soft tissue changes between the BSSO group and Genio group, there were significant differences in the lower incisor, soft tissue B point (B'), and soft tissue Pogonion (Pg') (p < 0.5). The mean ratio of hard and soft tissue changes for B/B', Pg/Pg', and Menton/soft tissue Menton after surgery in the BSSO group was 0.997, 0.965, and 1.022 respectively, and 0.824, 0.602, and 0.887 respectively in the genio group. Significant differences were found between the two groups. There were significant differences in lip thickness (B-B', Pg-Pg') in the Genioplasty group between pre and postsurgery, but not in the BSSO group. Pogonion to Labrale inferior and B' had a correlation coefficient of 0.833, 0.922, respectively for the BSSO group, and 0.775, 0.799 for the Genio group. Conclusions: The results indicate that there is a significant difference between bilateral sagittal split osteotomy with or without genioplasty in the lower facial esthetics values. The combination of mandibular setback and genioplasty had a smaller change in soft tissue thickness of the symphysis area after surgery than that of mandibular setback only.

• The korean journal of orthodontics
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• v.34 no.5 s.106
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• pp.394-407
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• 2004

The Purpose of this study was to evaluate the effect of the lower third molar on treatment time and distal en masse movement of the lower dentition in Giass III malocclusions. Thirty subjects (9 males and 27 females) were selected, all of whom were diagnosed as Glass III malocclusion and treated by fixed appliances without premolar and/or molar extraction. They were divided into three groups Group 1 consisted of 12 subjects. whose lower third molars were not extracted during the whole orthodontic treatment. Group 2 consisted of 8 subjects. whose lower third molars were extracted after WEAW application and before removal of the orthodontic appliances. Group 3 consisted of 10 subjects whose lower third molars were extracted before MEAW application. For each subject. overall treatment time and duration of MEAW application were determined. In addition. pre-treatment and post-treatment lateral cephalometric radiographs were analyzed. All data were Processed statistically with ANOVA, and the conclusions were as follows: There was no significant difference among the groups in overall treatment time However, duration of MEAW application was longer in Group 2 than in Group 1 or Group 3. The overjet that was established after orthodontic treatment was largest in Group 3, in which the lower third molars were extracted befor MEAW application. After orthodontic treatment, IMPA decreased in Group 3. but increased in Group 1 and Group 2. There was no significant difference among the three groups in the translation of lower second molars However the tipping movement of lower second molars was significantly different, highest in Group 2 and lowest in Group 1 Therefore. it is thought to be better for the orthodontic treatment of Class III malocclusions to extract the lower third molars before MEAW application. In Group 2, the mandibular plane angle was decreased as a result of forward rotation of the mandible This skeletal change was thought to bring about the difficulty of treatment.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.4
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• pp.389-403
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• 2008

In Angle's Class III malocclusion, which has higher incidence in Korean than Western, depressed midfacial profile with protruded lower lips and mandible may give rise to many functional, esthetic, psychological, social problems. Due to the different malocclusion incidence according to racial differences, many previous studies focused on the relationship between Class II malocclusion and nasal airway obstruction. Previous studies used lateral cephalography which has limitations of 2 dimensional image with projection error and identification error. Therefore, the purpose of this study was to analyze morphologic differences in the nasal airway between normal occlusion and Angle's Class III malocclusion patients using 3-dimensional facial computed tomography. Thirteen normal occlusion(7 men and 6 women) and sixteen skeletal Class III(7 men and 9 women) patients were selected and 3-dimensional facial computed tomography taking was performed. Comparison between two group in volume and sectional area of nasal airway were carried out. The results were followed. 1. In the comparison of absolute nasal airway volume, oropharyngeal space of experimental group were larger than control group but there are no significant difference in other. 2. In the comparison of relative nasal airway volume, oropharyngeal space of experimental group were larger than control group but there are no significant difference in other. 3. In the oropharyngeal space width on frontal and lateral view, the similar tendency was revealed between two groups. 4. In the lateral curvature of nasal airway, the similar tendency was revealed between two groups.