• The korean journal of orthodontics
• /
• v.16 no.2
• /
• pp.123-133
• /
• 1986

The purpose of this study was to collect the information of the straight-wire appliance and to determine the amount of second-order bends in clinical orthodontics. The author analysed the study model of 50 individuals with normal occlusion and results were obtained as follows. 1. The crown angulation was 4 degree in upper central incisor, 7 degree in upper lateral incisor, and 0 degree in lower central incisor and lateral incisor. 2. The crown angulation was 8 degree in upper cuspid and 2 degree in lower cuspid. 3. The crown angulations were 4 degree in upper first bicuspid, upper second bicuspid and lower second bicuspid and 1 degree in lower first bicuspid. 4. The crown angulation was 3 degree in upper first molar, 0 degree in upper second molar, 5 degree in lower first molar and 8 degree in lower second molar. 5. The crown angulations in lower arch were progressively increased from first premolar to second molar. 6. In upper arch, as the crown angulation of one tooth was increased, those of adjacent teeth were increased, too. 7. In the case of lower arch, the crown angulation of cuspid was increased as that of lateral incisor was increased, the crown angulation of second premolar was increased as that of first premolar was increased, and similarity the crown angulation of second molar was increased as that of first molar was increased.

• Journal of Oral Medicine and Pain
• /
• v.16 no.1
• /
• pp.121-136
• /
• 1991

This study was undertaken to obtain the data for age determination following the calcification degree of the second molar, third molar in the point of forensic odontology. The intraoral panoramic radiograph of 1600 male and 1600 female (100 persons each age) ranging from 7 to 2 years of age were studied. The developmental state of the second molar and third molar were divided into 12 stages following the calcification degree and correlations of second molar developmental stage and statistically analyzed. The results were as follows : 1. There was remarkable correlation between the development of the second molar, the third molar and age. 2. There was no significant developmental differences between the right and left second molar, third molar.(p>0.05) 3. The developmental stages of the lower second molar was more advanced than those of upper second molar. (p<0.05) 4. The developmental stages of upper third molar was more advanced than those of lower third molar. (p<0.05) 5. Both the developmental stages of second, third molars were earlier in the female than in the male. (p<0.001) 6. For the purpose of age estimation according to developmental stages of the second, third molar, linear equations are as follows. (p<0.001) second molar : male upper : Y=1.3927X + 0.2213 (r=0.72) lower : Y=1.4132X + 0.0012 (r=0.78) female upper : Y=1.4914X + 0.2151 (r=0.73) lower : Y=1.5429X - 0.0911 (r=0.78)

• Journal of Dental Rehabilitation and Applied Science
• /
• v.16 no.2
• /
• pp.93-104
• /
• 2000

Orthodontic treatment in conjunction with second-molar extraction has been a controversial issue among orthodontists over many decades. The aim of this study was to investigate the treatment effects of upper second molar extraction cases. The sample included 19 upper second molar extraction orthodontic cases(ten Angle's Class I's and nine Class II's, average age=13Y 6M) cared at Kyung-Hee University Department of Orthodontics. Lateral cephalometric radiographs were taken before and immediately after treatment. Seventy-nine points were digitized on each cephalogram and 38 cephalometric parameters were computed comprising 22 angular measurements, 13 linear measurements, and 3 facial proportions. The data obtained from each malocclusion group were analyzed by paired t-test. The statistical results disclosed that there was no significant change in skeletal pattern after treatment except for that accountable by growth while there was statistically significant change in dentoalveolar and soft tissue patterns. There were no significant changes in Bjork sum, posterior facial height /anterior facial height and lower anterior facial height /anterior facial height. No significant changes in anteroposterior position of maxilla and palatal plane were manifested. Although facial axis and lower facial height was slightly increased and the mandible was rotated backward and downward, there was no remarkable change in the mandibular plane. There were statistically significant changes in distal movement of upper first molar, molar key correction and overjet reduction while there was no change in the occlusal plane. The upper lip was slightly retracted simultaneously with slight increase in nasolabial angle. These results signify that distalization of upper dentition with the second molar extraction does change occlusal relationship without gross modifications in the craniofacial skeletal configurationson. Henceforth the second molar extracted would be recommended to treat severe anterior crowding and protrusion with minor skeletal discrepancy.

• The korean journal of orthodontics
• /
• v.17 no.1
• /
• pp.93-106
• /
• 1987

The purpose of this study was to investigate the fittness of Golden relation items was advocated by Ricketts whether or not it is applicable to the young adult Korean dentitions and also to evaluate the several new Golden relation items conducted by the author. The material was consisted of 81 dental casts (34 male, 47 female) with ideal occlusion, which never undergone orthodontic, prosthodontic procedures. Measurements were made on the arch dimensions using sliding caliper (Mitutoyo. Co) and data were computerized and analyzed. The findings of this study were as follows, 1. The Golden proportion advocated by Ricketts dose not seem to directly applicable to the Korean normal dentition, however, the modification from the Ricketts' original shows the Golden proportion as follow: A first series of progressive Golden relations was found on the Golden ratio among the lower central incisors width, the inter mesioincisal width of the upper lateral incisors, and the upper first premolars width. A second series was found on the Golden ratio among the lower lateral incisors width, lower inter canine tips width and theupper first molar distal cusp tips width. A third series was found on the Golden ratio between the inter distal aspect width of e lower canine and the mesial cusp tips width of the lower second molars or inter cusp tips width of upper second premolars. 2. In addition to Ricketts' original, 4 new Golden proportions were found in young adult Korean dentition, these are as follows; The tips of lower canine width had Golden relation with the width of the upper first premolar buccal cusp tips or the width of the lower first molar central fossae. The distal aspect of the lower first premolars had Golden relation with the buccal surface widths of the lower or upper second molars. The width of upper lateral incisors had Golden relation with the upper second molar height. The width of the lower canine tips had Golden relation with the lower second molar height.

• The korean journal of orthodontics
• /
• v.23 no.1 s.40
• /
• pp.123-136
• /
• 1993

The purpose of this report is to present the successful improvement of occlusal relationship and facial esthetics in class II division 1 malocclusion with severe labioversion of upper anterior teeth and severe overjet, and in class II malocclusion with infraversion of bilateral maxillary canines by MEAW mechanics, which enables us to get effective distal on mass movement of maxillary dentition, with upper second molar extraction. After treatment, there were natural contact points at canine and premolar regions, normal occlusal relation-ship and treatment results, satisfied the gnathologic concept, in this 2 cases. Compared with the routine treatment with premolar extraction, the treatment time and patients' discomfort were reduced. And the MEAW mechanics, which enables us to get effective distal on mass movement of maxillary dentition, resulted in reduction of the treatment time and getting the good treatment results. Consequently, the majot concerns in orthodontic treatment are appropriate diagnosis and treatment plan, so, the application of second molar extraction with appropriate case analysis and diagnosis is very helpful to orthodontic treatment.

• Journal of Oral Medicine and Pain
• /
• v.8 no.1
• /
• pp.121-126
• /
• 1983

This study is conducted with a view to make correct sexual differentiation by the utilization of discriminant functions. For that purpose were randomly sampled out 148 young adults testes, comprising 67 males and 81 females, ranging from 15 through 18 years fo age. Based on the values made available from the measurement of 6 items corresponding to the maxillary cast models, a statistical analysis was made to abstract feasible discriminant functions. The results findings are as follows: 1. The mean value by sex indicates, in all items, higher one in male group than in female group. 2. Through the measurement were defined as singnificant items in sexual differentiation the bucco-lingual dimensions of canine, 1st-molar, 2nd molar, and 1st bimolat width. 3. Derived from the value from measurement items were discriminant functions with the intention of applying them to sexual differentiation, as follows: 1) Y=-25.4112+0.7513BL3+0.3298BL4-0.2854BL5+0.7350BL6-0.3482BL7+0.2893AW (as tested by Method I) 2)Y=-25.0628+0.7737BL3+0.7468BL6-0.3885BL5+0.2951AW(as tested by Method II) BL3 : Bucco-lingual dimension of upper canine BL4 : Bucco-lingual dimension of upper first prmolar BL5 : Bucco-lingual dimension of upper second premolar BL5 : Bucco-lingual dimension of upper first molar BL6 : Bucco-lingual dimension of upper second molar AW : Upper first bimolar width 4. Sexual defferentiation in terms of descriminant functions represented a probility of 74.6%.

• Restorative Dentistry and Endodontics
• /
• v.6 no.1
• /
• pp.63-70
• /
• 1980

This study was to determine the incidence of pulp stone in each tooth by means of analyzing 375 orthopantomograph taken from 375 patients (252 male), 125 female). The pictures were grouped by age, 20s, 30s, 40s, 50s, and sex. The results were as follows 1. In the group of 20s, male showed the highest incidence in the first molar (40~50%) and the second highest was in the 2nd molar about 35%~50%. In the female group, the first molar and the second molar showed 25%~40%. 2. In the group of 30s, the highest value was found on the first molar and the next was the 2nd molar which appeared 30%~40% in male. In the female, the first molar was 55%~70% and the 2nd molar 30%~50% 3. In the group of 40s, the first molar represented highest value about 45%~60% and the 2nd molar was 40~60% in the male. Female group also showed in the first molar 30%~50% and the second molar 25~30%. 4. In the group of 50s, the highest incidence was 40%~60% on the first molar and next was 35%~50% on the second molar in male, in femalegroup showed 30%~50% on the first molar and 25%~50% on the second molar. 5. The incidence in upper was higher than that of lower. 6. Comparison between right and left showed right was slightly higher than left side.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.4 no.1
• /
• pp.7-18
• /
• 1977

The author carried out to determine the normal range of eruptive time, average age and order of eruption of primary teeth in korean infants. The examimation was given to 1757 healty infants(Male 1032, female 725) from afterbirth 4 months to 32 months. The results was as fallows. 1. The eruption of primary teeth was 0.57 months earlier in male than in female. 2. The average month of eruption of primary teeth was as follows; Upper primary central is $9.66{\pm}0.19$ months Upper primary lateral is $11.58{\pm}0.18$ months. Upper primary canine is $18.06{\pm}0.32$ months. Upper first primary molar is $16.45{\pm}0.29$ months. Upper second primary molar is $24.28{\pm}0.51$ months. Lower primary central is $7.50{\pm}0.12$ months. Lower primary lateral is $12.87{\pm}0.16$ months. Lower primary camine is $18.82{\pm}0.34$ months. Lower first primary molar is $17.66{\pm}0.37$ months. Lower second primary molar is $23.89{\pm}0.51$ months. 3. The eruptive order of the korean is different from that of the American and same to that of Japanese. 4. There is no significant right and left arch. 5. Generally, the eruption of primary teeth on the upper is 1.08 months earlier than on the lower; but the upper central is 2.16 months later than the lower and the upper second primary is 0.39 months later than the lower.

• Imaging Science in Dentistry
• /
• v.43 no.4
• /
• pp.289-293
• /
• 2013

Purpose: This study was performed to determine the relationship between the stage of tooth eruption (both vertical and mesio-angular) and chronological age. Materials and Methods: Indirect digital panoramic radiographs were used to measure the distances from the dentinoenamel junction (DEJ) of the second molars to the occlusal plane of the second molar teeth and of the adjacent third molars in 264 Thai males and 437 Thai females using ImageJ software. The ratio of those distances was calculated by patient age, and the correlation coefficient of the ratio of the third molar length to the second molar length was calculated. Results: The correlation between the height of the vertically erupted upper third molar teeth and age was at the intermediate level. The age range of ${\geq}15$ to <16 years was noted to be the range in which the correlation between the chronological age determined from the eruptional height and actual chronological age was statistically significant. The mean age of the female subjects, in which the position of the right upper third molar teeth was at or above the DEJ of the adjacent second molar but below one half of its coronal height was $19.9{\pm}2.6$ years. That for the left side was $20.2{\pm}2.7$ years. The mean ages of the male subjects were $20.1{\pm}3.3$ years and $19.8{\pm}2.7$ years for the right and left sides, respectively. Conclusion: It might be possible to predict chronological age from the eruption height of the wisdom teeth.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.21 no.2
• /
• pp.486-490
• /
• 1994

Maxillary first molar is the key in normal occlusion. Mesial drifting of maxillary first molar result form early loss of second deciduous molar. Mesial drifted maxillary first molar was treated by headgear, Hawley appliance with screw, brasswire, etc. But, these appliance should be necessary for patients cooperation. Recently, several appliance for molar distalizing without patients cooperation has been introduced. We are reporting in this paper about distalizing of mesial drifted maxillary first molar because of early loss of deciduous second molar by open coil jig. Distalization of molar by open coil jig is predictable, rapid, painless method without mecesscity of patient cooperation.