• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.1
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• pp.122-134
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• 2000

The aim of this study is (1) to establish the baseline information concerning the width of keratinized gingiva, depth of gingival sulcus and width of attached gingiva on the buccal surface of the teeth: and (2) to determine the relationship between the above values and tooth eruption: and (3) to estimate the frequency of mucogingival problems. The results were as follows; 1. The mean width of attached gingiva of the children aged $6\sim12$ proved to be wider in the maxilla than in the mandible. Of the primary teeth, the widest width was found in the areas of maxillary primary lateral incisors and maxillary primary canines(3.50mm and 3.55mm). The narrowest was noted in the area of mandibular first primary molars(1.34mm) In the permanent dentition, the greatest width was found in the areas of maxillary permanent lateral incisors (3.00mm). The narrowest was noted in the area of mandibular first premolars(0.55mm). 2. In the primary dentition, the width of attached gingiva of primary canines and first and second primary molars became wider from the age of six as the age increased. In the permanent dentition of the boys, only mandibular central incisors and maxillary first molars showed the tendency towards increase in the width of attached gingiva with increasing age. In the permanent dentition of girls, central and lateral incisors of both jaws and maxillary first molars showed statistically significant increase in the width of attached gingiva with increasing age(p<0.05). 3. At the age of tooth change, the attached gingiva of primary teeth were almost wider than those of successive permanent teeth (p<0.05). 4. During the period of 6 to 12 years of age, the width of keratinized gingiva and the depth of gingival sulcus of permanent tooth at the age of twelve were larger than those of primary tooth at the age of six (p<0.05). 5. The maximum in the frequency of mucogingival problems was found in the areas of upper and lower first primary molars of primary dentition, and in the upper and lower first premolars of permanent dentition regardless of sex. The frequency was higher in primary teeth than in the corresponding successive permanent teeth These teeth showed tendency towards increase in mucogingival problems with age.

• The Journal of the Korean dental association
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• v.39 no.3 s.382
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• pp.199-210
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• 2001

• Restorative Dentistry and Endodontics
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• v.22 no.2
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• pp.731-738
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• 1997

A retrospective in vivo study of endodontically treated mandiblar molars was conducted. The radilographs and clinical records of mandibular molars that had been treated endodontically in the Dental hospital of Yonsei University from 1986 to July 1997 were reviewed and categorized. A total of 1751 cases were studied and following results were obtained. 1. The number of root canals in mandibular first permanent molar in a Korean population revealed three in 53.2 %, four in 23.0 %, two in 18.4 %, C-shaped canal in 5.0 %, and one in 0.4 %. 2. In mandibular second molar, three canals was observed in 53.2 %, four in 22.2 %, two in 14.9%, C-shaped canal in 9.1 %, and one in 0.6%. 3. In the results of the percentage of 4 canals of mandibular first molars at various age, before age 20, 37.7 % was obtained whereas 19.3 % after 30. 4. 7.94 % of mandibular first molars examined were found to have three roots. 5. The mandibular second molar had C-shaped canals in 9.1 %.

• Journal of the korean academy of Pediatric Dentistry
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• v.40 no.1
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• pp.48-52
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• 2013

Ectopic eruption of the first permanent molar is an abnormal positioning of this tooth, causing a premature resorption of the distal surface of the second primary molar. It occurs in approximately 3~4% of the population and the maxillary arch is usually affected. While 66% of ectopically erupting permanent molars are corrected spontaneously without treatment (i.e. a reversible type), active treatment is necessary for irreversible ectopic eruption cases. The treatment modalities have been divided into two categories: interproximal wedging and distal tipping. Interproximal wedging is indicated for minimal impaction and when the impaction is severe, distal tipping techniques are required. Although much has been written about treatment modalities on unilateral ectopic eruption of the first permanent molar, few reports mention bilateral ectopic eruption cases. In this report, two cases of bilateral ectopic eruption of the first permanent molars in young patients are presented. We describe the use of a modified bilateral Halterman appliance for correction of these cases and the clinical results were satisfactory.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.2
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• pp.297-304
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• 2008

The purpose of this study was to evaluate a 3-Dimensional laser scanner for the space analysis after loss of a primary first molar. Six children with premature loss of a primary first molar were examined using study models taken before and after the extraction. The results were as follows: 1. There was no change in primary molar space after the extraction of a maxillary primary first molar However, 2 out of 3 children experienced primary molar space loss in extraction side of a mandibular primary first molar. 2. Arch width and arch perimeter showed no difference between initial and final model. 3. All primary canines did not show any changes in inclination. Maxillary primary second molars had similar changes in both extraction and control side. However, 2 out of 3 mandibular primary second molars in extraction side showed more lingual tipping compared to control side. Mandibular permanent first molars tipped more lingually in extraction side. 4. In angulation, primary canines showed nothing of significance. Mandibular primary second molars tipped more mesially in extraction side than in control side. Maxillary permanent first molars have increased distal angulation after extraction of primary first molars in both side.

• Journal of the korean academy of Pediatric Dentistry
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• v.48 no.2
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• pp.229-236
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• 2021

Eruption disturbances of the mandibular first molars can cause multiple problems in occlusal development although they are extremely rare. Early diagnosis and treatment are very important to prevent complications associated with eruption disturbances. The present case report describes the treatment of two cases of eruption disturbances of the mandibular first permanent molar. A fixed appliance composed of a cantilever spring with mandibular second deciduous molar as an anchor tooth was used to tract the impacted mandibular first permanent molar. The success of both cases shows that this novel traction appliance can be used to induce the eruption of an impacted mandibular first permanent molar within a short time in patients with intact mandibular second deciduous molar as an anchor tooth.

• Journal of Technologic Dentistry
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• v.11 no.1
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• pp.65-70
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• 1989

The development of the lobe pattern in the human dentition plays a part in the form and function of each individual teeth. In order to determin the morphological categories used to describe the occlusal surfaces of the maxillary and mandibular molars, the variation of the developmental grooves which separate each lobe in the molars was examined and analysed. The obtained conclusions were as follow. 1. Most of the maxillary first molars with more distinct and more developmental grooves than the other molars but in most cases of the third molar, a heart-shaped outline due to poorly developed or abscent distolingual cusp was most frequent and in this case the third molar had the 3 cusps separated by the central developmental groove and the buccal developmental groove. 2. In most cases, the mandibular first molar had the 5-cusp type that the groove patter resembles a Y, the second molar the 4-cusp type arranged in such a way that the buccal and lingual developmental grooves meet the central developmental groove at right angle on the occlusal surface and many instances of the mandibular third molars had the 5-cusp thpe with a+groove pattern which separatess the mesiolingual cusp from the distobuccal cusp and the 4-cusp type with a+groove pattern. 3. The maxillary and mandibular third molar were most variable in the developmental groove.

• Journal of the korean academy of Pediatric Dentistry
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• v.44 no.3
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• pp.370-377
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• 2017

Molar-incisor malformation (MIM) is a recently described dental anomaly characterized by root malformation in permanent first molars accompanied sometimes by abnormal root forms in primary second molars or enamel defects in maxillary central incisors. This report presents three cases of MIM along with a review of previous studies. Three patients exhibited abnormal root forms in the permanent first molars, with varying degrees of deformation. Two of the patients experienced medical events at birth. One of the patients was a monozygotic twin, whose twin sister exhibited normal dentition without any significant abnormalities. The present report also reviews recently reported cases of MIM in literature. In the management of MIM-associated clinical issues, consideration of microscopic features and accompanying characteristics might facilitate early diagnosis and comprehensive treatment planning.

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.3
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• pp.337-343
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• 2020

Molar-incisor malformation (MIM) is a new type of root anomaly reported recently. The characteristics of MIM are dysplastic root formations, constriction of pulp chambers and presence of calcified matrices at the level of cementoenamel junction in permanent first molars and primary second molars. In some cases, permanent maxillary incisors are also affected. The permanent first molars of the patient in this case report were affected with MIM. Generalized pulp stones were observed in overall primary dentition. Micro-computed tomography (micro-CT) imaging and scanning electron microscope-energy dispersive X-ray spectrometer analysis were performed on the extracted mandibular first molar and maxillary primary second molar of the patient. Micro-CT images revealed the discontinuity of enamel directly connected to an accessory canal of the root.

• The korean journal of orthodontics
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• v.11 no.2
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• pp.143-150
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• 1981

Casts of 180 Korean male and female with normal occulsion of early permanent dentition (from dental age of Hellman III C, to IV A) were studied to measure the mesiodistal crown diameters and to calculate the coefficients of correlation between the teeth. From the study, the following conclusions were made: 1. Mesiodistal dimension of maxillary central incisors, canines, first molars and mandibular canines, first premolars, second premolars and first molars of male are larger than that of female. 2. Korean teeth are roughly intermediate between those of American Caucasian and those of American Negro. 3. In both sexes, the relation between the first and second premolars appeared highly correlated not only in the maxillary arch but also in the mandibular arch, and the relation between the central incisor and lateral incisor appeared highly correlated in the mandibular arch. 4. The relation between the maxillary and mandibular first premolars appeared highly correlated in both sex, and the relation between the maxillary canine and mandibular canine in male as well as between the maxillary central incisor and mandibular central incisor in female appeared highly correlated.