• 대한치과교정학회지
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• 제41권2호
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• pp.127-137
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• 2011

Objective: The aim of the study was to compare the opening and protrusive mandibular movements between Class I and Class II malocclusions in healthy adolescents by clinical and axiographic evaluations. Methods: Mechanical axiography was performed on non-orthodontically treated, temporomandibular disorder (TMD)-free adolescents (12 - 16 years) with Class I (n = 38, 16 boys, 22 girls) or Class II (n = 40, 19 boys, 21 girls) malocclusion. Opening and protrusive movements were measured clinically and axiographically. Intergroup comparisons were evaluated by t-tests. Results: In opening movement, the maximum clinical opening capacity was significantly different (p ${\leq}$ 0.05) between the groups. In protrusive movement, the Class II group had significantly greater maximum clinical protrusion (p < 0.001) and maximum axiographic protrusive length (p < 0.01) than the Class I group. No significant difference in the other opening and protrusive axiographic measurements was observed. Conclusions: TMD-free adolescents with Class II malocclusion have increased protrusive capacity compared with TMD-free adolescents with Class I malocclusion; however, the detected differences could be normal variations during adolescence.

• 대한치과교정학회지
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• 제48권1호
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• pp.11-22
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• 2018

Objective: The aim of this study was to determine cephalometric factors that help predict favorable soft-tissue profile outcomes following treatment with the Class II Twin-block appliance. Methods: Pre- and post-treatment lateral cephalograms of 45 patients treated with the Class II Twin-block appliance were retrospectively analyzed. Profile silhouettes were drawn from the cephalograms and evaluated by three orthodontists in order to determine the extent of improvement. Samples were divided into a favorable group (upper 30% of visual analogue scale [VAS] scores, n = 14) and an unfavorable group (lower 30% of VAS scores, n = 14). Skeletal and soft-tissue measurements were performed on the cephalograms and an intergroup comparison was conducted. Results: An independent t-test revealed that the following pre-treatment values were lower in the favorable group compared to the unfavorable group: lower incisor to mandibular plane angle, lower incisor to pogonion distance, point A-nasion-point B angle, sella-nasion line (SN) to maxillary plane angle, SN to mandibular plane angle, gonial angle, and symphysis inclination. The favorable group had a larger incisor inclination to occlusal plane. Moreover, the favorable group showed larger post-treatment changes in gonial angle, B point projection, and pogonion projection than did the unfavorable group. Conclusions: Class II malocclusion patients with a low divergent skeletal pattern and reduced lower incisor protrusions are likely to show more improvement in soft-tissue profile outcomes following Class II Twin-block treatment.

• 대한치과교정학회지
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• 제14권1호
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• pp.151-160
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• 1984

This study was designed to get the informations of the mesiodistal axial inclinations of the posterior teeth and of the relationships between these and other angular measurements of facial bony structures in normal occlusion and malocclusion groups using lateral roentgenocephalograms. The subjects consisted of 73 normal occlusions (31 males 42 females), 38 Class II Division 1 malocclusions (17 males 21 females) and 47 Class III malocclusions (19 males 28 females). The findings of this study are as follows : 1. In mandible, the posterior teeth axes of Class II Division 1 malocclusion group were inclined more mesially and those of Class III malocclusion group were inclined more distally than normal occlusion group. In maxilla, Class II Division 1 malocclusion group showed more distal inclination and Class III malocclusion group showed more mesial inclinaton of 1st, 2nd premolars and more distal inclination of 1st, 2nd molars than those of the normal occlusion group. 2. There was a tendency for teeth axes to maintain nearly the same inclination in relation to occlusal plane irrespective of various OMA and OPA in each group. 3. F M A, P M A and O P A were the largest in Class II Division 1 malocclusion group and O M A, GoA were the largest in Class 111 malocclusion group. 4. There were high correlationships between mandibular teeth inclinations related to mandibular plane and 4 angular measurements except OPA, and between maxillary teeth inclinations related to palatal plane and OPA.

• 대한치과교정학회지
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• 제25권6호
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• pp.665-674
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• 1995

The purpose of this study is to investigate the cephalometric characteristics of the open-bite patients with DJD of TMJ. The DJD open-bite cases were compared with normal samples and Class II open-bite cases with normal TMJ respectively. Twenty three open-bite patients with bilateral DJD of TMJ($13.9\~35.3$ yens old, Group I) were selected from the Department of Orthodontics, SNUDH. Group ll consisted of thirteen Class II open-bite cases($13.2\~27.4$ years old) with no TMD signs/symtoms and good condylar shapes. Group III samples were the forty eight healthy dental students who have Class I molar relationships with no history of orthodontic treatment, good facial balance and no TMD symptoms($20.0\~26.8$ years old). First, sixty measurements in the lateral cephalometric radiographs and analysis of variance(P<0.05, Scheffe) were used to compare these three groups. The seven measurements showed significant difference(p<0.05) between Group I and Group II. After analysis of variance, six of them were used for the discriminant analysis(Wilks' stepwise analysis) and the discrminant function for Group I/Group II was obtained. The results and conclusions were as follows : In most of the measurments, Group I and Group II showed the same skeletal and dental characteristics. But seven of the sixty measurements(FH-PP angle, SNB, FH-ArGo angle, articulare angle, genial angle, upper gonial angle and Ar-Go length) were significantly different(p<0.05) between Group I and Group II. These differences may be explained by the fact that in DJD cases the mandible rotated backward due to the shortening of the ramus following the degenerative destruction of condylar head and its surrounding structures. The resulting discriminant function was : $D={-0.120X}_1+{0.066X}_2+{0.144X}_3-{0.058X}_4+2000,\;where\;X_1=ArGo\;length(mm),\;X_2=SArGo\;angle(degree),\;X_3=FH-PP\;angle(degree),\;X_4=Gonial\;angle(degree)$. Mean of the group centroids was -0.555 and percent of the 'grouped' cases correctly classified was $88.89\%$.

• 대한치과기공학회지
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• 제29권2호
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• pp.197-211
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• 2007

With the development of orthodontics and increasing concerns on physical appearance, the number of patients has been steadily increasing. It is quite important not only to make effective cure plans and accurate diagnoses but also to have a thorough grasp of patients' malocclusion types and their occurrence frequency, in addition to patients' personality in order to cure the patients appropriately. This study is based on 946 malocclusion patients who had visited Chong-A Dental Hospital from 1999 to 2004 and investigated their aspects of malocclusion and characteristics of their gender, age and residence. The results are as follows. 1. The number of patients per year had been decreased until 2001, after which year the number had fluctuated. The number was the largest in 1999, 169 and the smallest in 2001, 140. Female occupied 68.0% of the total, twice as many as male, 32.0%) 2. Based on the Angle's classification, 19 or over year - old group was the largest of the total, 59.3% and 6 or younger year - old group, the smallest, 0.5%. The 19 or over year old group was less than a half of the total (47.4%) in 2003 and there were no patients who belonged to the 6 or younger year - old group in 2003 and 2004. 3. Distributions on the types of malocclusion have shown that 39.9 % of the total are in the Class I, the largest, 31.0% in the Class I and 29.2 in the Class II, the smallest. 1) The number of the ClassI was 73, the largest, that of the Class III being 35, the smallest in 1999. On the whole, the number of the Class I accounted for the largest part of the total. 2) The number of male patients in the Class II was the smallest, generally being the largest in the Class I. In case of female, that of the Class III was the smallest. 3) Based on the age, the Class I was the highest in between 7 and 13 age group, the Class III the lowest. The Class I occupied the largest around 40%. 4) In the shape of physiognomy, the meso occupied the largest part among all the Class, of which the Class II was the highest, 64.2%. The bracy was the largest in the Class I, and the dolicho in the Class III. 5) In the profile, the convex shape was the largest in the Class I and II, and especially in the Class II, over 3/4 of the total, 75.4%. In contrast, the direct shape was the largest in the Class III and the sunken shape occupied 33.3%, which was nearly ten times more than the case of the Class I and III. 6) In the asymmetry of physiognomy, the number of patients of the Class IIIwas the largest, 34.1% and that of the Class II, the smallest, 19.5%. It was found that about one fourth of the malocclusion patients were under the asymmetry of physiognomy. 4. In the distribution of patients' residence, 81.4% were from the Seoul Metropolis and 48.2% from Gangnam-Gu where Chong-A Dental Hospital is located and Seocho-Gu and Songpa-Gu which are adjacent to Gangnam-Gu.

• Restorative Dentistry and Endodontics
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• 제18권2호
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• pp.357-367
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• 1993

The purpose of this study was to evaluate the fracture strength of class II restored premolars with amalgam, posterior composite, amalgam - Ketac silver, resin - Ketac silver restorations at marginal ridge. Fifty extacted maxillary and mandibular premolar teeth that were caries free, fracture free, and restoration free were selected and randomly divided into five groups : Group 1 : 10 intact teeth, Group 2 : 10 teeth with class II cavities and restored with, amalgam, Group 3: 10 teeth with class II cavities and restored with posterior resin, Group 4 : 10 teeth with class II cavities and restored with amalgam - ketac silver, Group 5 : 10 teeth with class II cavities and restored with resin - Ketac silver. All teeth were mounted in base of dental stone within metal rings of 2cm diameter, exposing only the crown portion. Class II mesio - occlusal or disto - occlusal cavities were prepared into specimens of Group 2 through 5 by using a No. 710 fissure bur. The occlusal portion was prepared to a faciolingual width of 1.5mm and a pulpal depth of 1.5mm. The proximal protion was prepared to a faciolingual width of 4mm, a occlusogingival height of 4mm, and a gingival floor of 1.5mm. The teeth in Group 2 and 3 were resotored with silver amalgam apd posterior resin respectively. In Group 4 and 5, proximal portions were first filled with Ketac silver 1.5mm gingivally and remaining cavities were restored with amalgam and posterior resin respectively. All specimens were stored in 100 % relative humidity at $37^{\circ}C$ for 48 hours before testing. All teeth were subjected to a compressive load in a Universal Instron Testing Machine at marginal ridges. The loads required to fracture the restorations were recorded in killograms and the data obtained were subjected to statisticall analysis. The results were all follows : 1. The fracture strength of Group 1 which were unprepared were $100{\pm}10.1\;kg$ and the higher values than Group 2, 3, 4, 5 which were prepared and resotred. 2. In restored groups, Group 2 had the higher fracture strength($81.8{\pm}12.4\;kg$) than other groups and Group 4 had the lowest fracture strength($66.8{\pm}9.2kg$). 3. There were significant differences between fracture strength of between Group 1 and Group 3, 4, 5(P<0.05), but not significant difference between fracture strength of Group 2, 3, 4, 5(P>0.05).

• 대한치과보철학회지
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• 제18권1호
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• pp.7-13
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• 1980

The purpose of this study was to evaluate the removable partial denture prescriptions including surveyed crowns and design of component parts sent to the laboratory technician. A total of 351 casess with prescription forms and master cast in maxillary and mandibular semi-edentulous situations collected from dental laboratory by random sampling were selected for this study. The evaluation and study observed here involved the classification of edentulous situations, status of abutment splinting, form of rest seats and guiding plane of surveyed crows, location of maxillary major connectors and tripodig marks on the master casts. Removable partial denture prescriptions contained (1) general request (upper and lower cast framework), (2) types of metal, (3) location of retainer(retention, lingual bracing, rest area, guiding plane surface), (4) location and type of major connector, (5) relief area and amount, (6) and other specific instructions. The following informations based on the classified groups such as Group I was those cases sent with no real prescriptions. They say 'make a partial.' No prescriptions, no thought beforehand, Group II was those cases sent with a minimal prescriptions. They say 'make a partial with clasps on May be some preparations, usually inadequate. Group III was those cases sent with a moderately good prescription. Adequate but could be much better. No tripoding but it tell what clasps go where. Still not good prescriptions. Group IV was good cases, tripoded with adequate prescriptions and a prescription which exactly describes what is expected from the laboratory. The analyzed results were as follows: 1. The normal form of rest seats and guiding plane of surveyed crowns in Class. I and Class. II edentulous situations on the maxillary cast were observed 31.9% and 27.89%, respectively. The abutment teeth and retainer without occlusal rests of Class. I and Class. II were showed 11.58% and 8.86%, respectively. In mandibular cases, the normal form of rest seats and guiding plane of surveyed crowns showed 27.54% and 8.82% in Class. I and Class. II situation. The abutment teeth and retainer without rest seats were showed 15.19%, respectively. 2. The splinted surveyed crowns of Class. I and Class. II maxillary edentulous situations in distal extension cases were showed 34.51% and 28.85%, but 28.52% and 10.29%, respectively. 3. The location and type of maxillary major connector delineated on the master cast were 66 cases (44.89%). 4. The results of 351 cases were classified as Group I 146(41.59%), Group II 115 (32.76%), Group III 57 (16.23%), and Group IV 33 (9.48%). 5. The delineation of abutment tooth for clasping were 176 cases (50.14%) among total of 351 cases. 6. The delineation of height of contour line were showed 45 cases (12.8%) in Group II, 14 cases (3.98%) in Group III and 33 cases (9.40%) in Group IV with total 92 cases (26.21%). 7. In surveying procedure, the delineation of tripoding marks and reference line were showed 17 cases (4.84%).

• 대한치과교정학회지
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• 제22권1호
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• pp.109-121
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• 1992

Temporomandibular joint is a major structure to play an important role in the function & stability of the occlusion as well as the stomatognathic system. Therefore, the TMJ is the structure that requires the complete analysis for diagnosing and planning treatment of pathologic changes by TMJ dysfunction and malocclusion. So, in this study, to evaluate TMJ situation in Korean malocclusion, based on the previous accomplishments, students of the dental college of Won-Kwang Univ. are surveyed and selected in terms of Angle's classification of malocclusion, whose TMJ radiographs were taken in the centric occlusion and centric relation. In each maiocclusion groups, the mean and standard deviation of anterior, posterior and superior joint space of the right, left and both side in CO & CR are evaluated and also those of the fossa height and the articular eminence angle of the right, left and both sides are evaluated. The obtained results were as follows: 1. In the correlation coefficient between the malocclusion groups, no other items except the posterior joint space of the right side in CR between in class I and class III are significant. 2. In the correlation coefficient between the right and left side, the each joint space in class I malocclusion group and class II malocclusion group are significant. 3. In the change of each joint space during the transmit from CO to CR, there is a tendency of increasing anterior joint space and decreasing posterior, superior joint spaces in class I, II malocclusion and increasing superior joint space and decreasing anterior, posterior joint space in class III malocclusion, which is significant in the correlation coefficient, but not significant in the T-test. 4. In each malocclusion group, the correlation coefficient between the posterior joint space and the superior joint space in C.R is highly significant. 5. The fossa height of class II malocclusion group is lesser than that of class I or class III, which is not significant in T-test. 6. In the correlation coefficient between Rt. and Lt. side in the fossa height, it is not significant in class I and class III group, but significant in class II malocclusion group. 7. The articular eminence angle of class II malocclusion group is larger then that of class I or class III groups, which is fairly significant. 8. In the correlation coefficient between Rt. and Lt. side in the articular eminence angle, it is significant in each malocclusion group.

• Restorative Dentistry and Endodontics
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• 제7권1호
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• pp.131-138
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• 1981

The purpose of this study was to evaluate the marginal leakage of composite resin. Preparing 144 class V cavities on freshly extracted noncarious teeth, composite resins were prepared and inserted by one dentist according to the manufacturer's instructions. The experiments were performed in two different groups; In group I; Class V cavities with $90^{\circ}$ cavosurface angle, In group II; Class V cavities with $135^{\circ}$ cavosurface angle. And each group was divided 2 subgroups; In control group; composite resin restoraions without acid etch technique. In experimental group; composite resin restorations with acid etch technique. All specimens were immersed in 0.05% crystal violet solution. Before examination, the restored teeth were subjected to thermal stress. The specimens were sectioned occlusogingivally through the center of the restorations with a diamond disk. The sections were examined under a reflected light microscope at 1 day, 7 days and 30 days after immersing the specimens in dye solution. The results were as follows; 1. Control group of group I and group II showed marginal leakage. 2. The degree of marginal leakage in experimental group was greater reduced than control group. 3. In control group, the degree of marginal leakage in group I was greater than group II. 4. In experimental group, there is not statistical differences of the degree of marginal leakage between group I & group II.

• 대한치과교정학회지
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• 제32권4호
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• pp.241-255
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• 2002

교정치료의 목표는 좋은 안모 균형과 치열의 안정을 얻는 것이며 이를 위해서는 부정교합의 다양한 원인에 상응한 치료를 시행해야 한다. 본 연구에서는 성인 골격성 II급 부정교합자의 측모두부규격 방사선학적 특징을 조사하기 위하여 성인 정상교합자 140명(남 70명, 여 70명)과 성인 골격성 II급 부정교합자 120명(남 60명, 여 60명)의 측모두부규격 방사선사진을 촬영하였으며 계측결과를 바탕으로 골격 및 치아, 연조직 59개 항목을 평가하여 다음과 같은 결론을 얻었다. 1. 수직적 거리 계측치 및 고경 비율은 골격 분석에서는 정상교합군과 II급 부정교합군에서 차이가 없었으나 연조직 분석에서는 다소 차이를 보였다. 2. II급 부정교합군이 정상교합군에 비해 하악골 길이는 더 작았으며 더 후방에 위치하였다. 3. 상악골의 길이와 전후방적 위치는 II급 부정교합군과 정상교합군 간에 차이가 없었다. 4. 코, 상순, 상악 연조직 부위의 전후방적 위치와 Nasolabial angle은 정상교합군과 II급 부정교합군 간에 차이가 없었으며 하악 연조직의 전후방적 위치에서 뚜렷한 차이를 보였다. 5. 상하악 전치의 수직적 길이(U1-HP, L1-MP)는 II급 부정교합군이 정상교합군보다 더 컸으며 제1대구치에서는 두 군간 차이가 없었다. 6.상순에 대한 상악전치의 노출도(U1-Stms), 상악전치의 치축 각도(U1-HP)는 두 군간 차이가 없었으며 하악전치의 치축 각도(IMPA)는 II급 부정교합군이 정상교합군보다 더 컸다. 7. II급 부정 교합군의 안모 유형 분류에서, 상악골은 정상 위치 하고 하악골이 후방 위치하는 경우가 43.3%로 가장 많았으며, 상악골과 하악골이 모두 정상 위치하는 경우가 28.3%, 상악골과 하악골이 모두 후방 위치하는 경우는 20.0%였다.