• Journal of the korean academy of Pediatric Dentistry
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• v.3 no.1
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• pp.19-31
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• 1976

To study the eruption pattern of the mandibular first permanent molar, the author took 263 cases of Oblique Cephalogram from age 3 to 6 years old children and observed the vertical and mesiodistal directional change and tooth axis change. The following results were obtained.; 1. The eruption pattern of the mandibular first permanenl molar was changed at about 60~66 months or calcification stage IX. 2. At the early stage, the path of eruption of the mandibular first permanent molar directed upward and forward and after calcification stage IX it changed to the direction of upward. 3. The height of the alveolar bone of the upper part of the mandibular first permanent molar was almost equal to that of the interseptal bone of the first and second deciduous molar, but the height showed gradual descent afterwards. 4. At the early stage, the distance from the distal end of the mandibular second deciduous molar to the anterior portion of the ascending ramus was 1.2~1.4 times larger than the mesio-distal diameter of the mandibular first permanent molar, but at the later stage it was enlarged 1.7~1.9 times larger than the mesiodistal diameter of the mandibular first permanent molar.

• Journal of the korean academy of Pediatric Dentistry
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• v.6 no.1
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• pp.53-63
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• 1979

To Study the eruption pattern of the mandibular second permanent molar, the author took 425 cases of Oblique Cephalogram from 6 to 13 years old children and observed the vertical and mesiodistal directional change and tooth axis change. The following results were obtained. : 1. The eruption pattern of the mandibular second permanent molar was changed at about 10.0~10.1 ages or calcification stage IX. 2. At the early stage, the path of eruption of the mandibular second parmanent molar directed upward and forward and after calcification stage IX it changed to the direction of upward. 3. At the early stage, the distance from the distal end of the mandibular first permanent molar to the anterior portion of the ascending ramus was 0.9~1.0 times larger than the mesio-distal diameter of the mandibular second molar, but at the later stage it was increased 1.4 times larger than the mesio-distal diameter of the mandibular second permanent molar.

• Journal of the korean academy of Pediatric Dentistry
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• v.11 no.1
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• pp.13-24
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• 1984

To Study the eruption pattern of the maxillary first permanent molar, the author took 266 cases of true lateral cephalogram (Male; 137 cases, Female; 129 cases) from 3 to 7 years old children and observed the vertical change and axial change. The following results were obtained: 1. The angle of axial inclination of the maxillary first permanent molar to the F-H plane increased gradually from age 3 to 7, except for age 6 in both sexes. There was a slight reversal of this motion at age 6. 2. The distance from the cusp of the maxillary first permanent molar to the occlusal plane slightly decreased from age 3 to 5, and rapidly decreased from age 5 in both sexes. 3. The change of angle of the axial inclination resulted in the distance from the distobuccal cusp of the maxillary first permanent molar to the occlusal plane decreasing more than that from the mesiobuccal cusp of the maxillary first permanent molar to the occlusal plane in both sexes. 4. The eruption of the maxillary first permanent molar generally was found to be earlier in girls than boys.

• The Journal of the Korean dental association
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• v.50 no.6
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• pp.322-328
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• 2012

Ectopic eruption of the permanent first molar is defined as the eruption of the tooth in an abnormal position or orientation. It may causes distal root resorption and premature exfoliation of the adjacent primary second molar and uncontrolled space loss is followed. Prolonged partial impaction of the permanent molar may also cause undetected caries or abscess formation of the neighbor teeth. The purpose of this paper is to provide a brief review regarding the etiology, classification, and different management techniques for correcting ectopic eruption of permanent first molar.

• The Journal of the Korean dental association
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• v.16 no.3 s.106
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• pp.196-198
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• 1978

Statistically inquiring into dental health index of upper and lower first permanent molar for 1520 pupils of primary school in seoul. I got a conclusion as follows: 1. Lower first permanent molar was lower than upper first permanent molar in dental health index and conversely in DMF rate. 2. Elder pupils were lower than younger pupils in dental health index and conversely in DMF rate.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.3
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• pp.284-291
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• 2016

In order to provide a diagnostic basis for predicting the possibility of the self-correction of ectopic first permanent molars, differences among normal eruption, reversible and irreversible ectopic eruption of maxillary first permanent molars were retrospectively analyzed. The angles of the long axes and the occlusal lines between the maxillary first permanent molar and the adjacent tooth were measured by panoramic radiographs. The occlusal relationship of second primary molars was also investigated. There is a statistically significant difference between the ectopic eruption group and normal group (p < 0.05), but not between the reversible and irreversible ectopic eruption groups (p > 0.05). The angles between the second primary molar and the first permanent molar, the second primary molar and the second permanent molar in ectopic groups showed a smaller degree than those of the control group. Mesial step was found more frequently in the ectopic eruption group than the normal group. In conclusion, the angulation of the first permanent molar and tooth germ of the maxillary second permanent molar showed close relation with ectopic eruption of the maxillary first permanent molar and ectopic first permanent molar is likely to occur in class III patients with maxillary deficiency.

• Journal of Oral Medicine and Pain
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• v.3 no.1
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• pp.11-22
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• 1977

In order to evaluate the normal eruption time of the Korean permanennt teeth, the author had examined the eruption phases of permanent first molars in 778 males and 653 female children aged from 5 to 9-year old and analysed. The eruption was divided into 4 phases; the tip of the crown can be seen, the dull occlusal surface of the crown can be easily seen, the crown is not in contact with its antagonist, and the crown is in contact with its antagonist. The obtained results were as follows : 1. It seemed that percentage of the eruptingand erupted permanent first molar in female by age was higher than that of male. 2. In general, percentage of the erupting and erupted permanent first molar by age was higher than that of upper first molar. 3. In the correlation of age with the eruption phase, the regression equation were "y=0.43x+5.61" on male upper first molar, "y=0.41x+5.60" on male lower first molar, "y=0.44x+5.47" on female upper first molar, and "y=0.38x+5.57" on female lower first molar respectively.n female lower first molar respectively.

• The Journal of the Korean dental association
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• v.21 no.12 s.175
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• pp.1005-1010
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• 1983

To study the eruption process of the permanent tooth, esp., 1st molar, the author took 303 cases of oblique cephalogram (Male. 162 cases, Female: 141 cases) from age 3 to 8 yea old children, and observed the vertical change and axial change. The result were as follow: 1. The mesial end of upper 1st molar was closer to the occlusal plane than the distal, and they were erupting toward the occlusal plane by aging. In the case of lower 1st molar, the distal end was closer to the occlusal plane than the mesial and the occlusion showed the tendency to accord with the plane to be settled by aging. 2. Eruption rate of the upper and lower 1st permanent molar increased rapidly at 5 or 6 years of age. 3. Axial inclination of lower 1st permanent molar to the mandibular plane decreased gradually from 3 years of age, except for 6 years of age. There was some increase at 5 or 6 years of age.

• The korean journal of orthodontics
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• v.17 no.2
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• pp.311-320
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• 1987

The purpose of this study was to investigate the growth changes of maxilla and mandible and position changes of first permanent molars of growing children The author analyzed the data using cephalometric roentgenogram of 43 boys and 39 girls age of 6 to 11 with normal occlusion The obtained results were as follows 1 The eruption path of maxillary and mandibular first permanent molar superimposed on TM-ANS and mandibular plane shows individual variation 2 There was no correlation between horizontal and vertical changes of maxillary first permanent molar, but positive correlation in mandibular first permanent molar 3 As the eruption, the forward changes of mandibular first permanent molar was significantly greater than that of maxillary first permanent molar 4 As the ages were increased, there were irregular growth changes of maxilla and mandible 5 Growth changes of lower anterior facial height was relatively stable 6 N-S-${\bar{6}}$ was stable after age 7.

• Journal of the korean academy of Pediatric Dentistry
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• v.11 no.1
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• pp.25-39
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• 1984

The author has sought to determine the time and the sequence of permanent teeth eruption in Korean children. The study group consisted of 15,671 healthy children (male 8,015 ; female 7,656) aged 5-13 years old who lived in Seoul or Cheongju. The results were as follows : 1. The eruption times of permanent teeth were 0.45 years earlier in females than in males. 2. The ages corresponding to $ER_{50}$ of permanent teeth were as follows : In Maxilla 1) central incisor was 7.37 yrs 2) lateral incisor was 8.50 yrs 3) canine was 10.83 yrs 4) 1st premolar was 10.30 yrs 5) 2nd premolar was 11.09 yrs 6) 1st molar was 6.49 yrs 7) 2nd molar was 12.79 yrs In Mandible 1) central incisor was 6.40 yrs 2) lateral incisor was 7.41 yrs 3) canine was 10.18 yrs 4) 1st premolar was 10.26 yrs 5) 2nd premolar was 11.15 yrs 6) 1st molar was 6.32 yrs 7) 2nd molar was 12.05 yrs 3. The eruption sequence of permanent teeth by Z-test was as follow: In Male 1st : Mandibular 1st molar, and Mandibular central incisor 2nd : Maxillary 1st molar 3rd : Maxillary central incisor 4th : Mandibular lateral incisor 5th : Maxillary lateral incisor 6th : Mandibular canine, Maxillary and Mandibular 1st premolar 7th : Maxillary canine 8th : Maxillary and Mandibular 2nd premolar 9th : Mandibular 2nd molar 10th : Maxillary 2nd molar In Female 1st : Mandibular 1st molar, and Mandibular central incisor 2nd : Maxillary 1st molar 3rd : Mandibular lateral incisor, Maxillary central incisor 4th : Maxillary lateral incisor 5th : Mandibular canine, Maxillary and Mandibular 1st premolar 6th : Maxillary canine 7th : Maxillary and Mandibular 2nd premolar 8th : Mandibular 2nd molar 9th : Maxillary 2nd molar 4. The corresponding permanent teeth in the mandible generally erupted earlier than the corresponding permanent teeth in the maxilla by an average of 0.73 years, but the mean eruption time of mandibular 1st premolars was almost the same as those of maxillary 1st premolars, and the mean eruption time of mandibular 2nd premolars was 0.06 years later than those of maxillary 2nd premolars. 5. There is no significant difference between left and right arch in the eruption time and sequence. 6. Generally, the ages of permanent teeth eruption tended to be earlier than those of Dr. Cha's data from 1963.