• The Journal of the Korean dental association
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• v.31 no.4 s.287
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• pp.295-304
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• 1993

• 대한치주과학회:학술대회논문집
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• 2006.11a
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• pp.68-69
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• 2006

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.1
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• pp.84-88
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• 2009

Tooth impaction refers to situations where a tooth fails to erupt due to mechanical blocking and remains unerupted beyond the normal time of eruption. It is commonly found in permanent dentition, but rarely in deciduous dentition. Tooth impaction is caused by systemic or local factors, and most common etiology is odontoma. Odontoma is also commonly found in permanent dentition, and rarely in deciduous dentition. We are presenting case of 4 year and 4 month year old girl, who had impacted and disto-angulated lower left deciduous second molar due to odontoma. We removed odontoma and performed orthodontic traction of impacted lower left deciduous second molar. Then, the impacted primary molar was erupted and acceptable occlusion was obtained.

• Journal of dental hygiene science
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• v.6 no.1
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• pp.29-34
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• 2006

This study was undertaken to compare the tooth and arch size between crowding patient and normal subjects. Two group of dental casts were selected on the basis of crowding patients and normal subjects. One group, consisting of 40 pair of dental casts(20 male and 20 female), exhibited noncrowded dentitions. A second group, consisting of 40 pairs of dental cast(21 male and 21 female), exhibited remarkably crowding need for orthodontic treatment. Tooth width measurements were made with a sliding digital caliper with Vernier scale neared 0.01 mm. Mean, standard deviation, T-test of the following parameters were used to compare two group : individual mesiodistal crown widths, arch width and arch length. The following result were obtained. In the mesiodistal crown widths, normal subjects had generalized larger teeth than Wheeler's results(human tooth size index), except for maxillary central incisor, maxillary 2nd premolar, mandibular canine, and mandibular 1st molar. In the orthodontic patients with crowded dentitions, the mesiodistal tooth crown widths were generalized larger teeth than noncrowded normal subjects. In the arch width and arch length, the crowded dentition group had smaller arch width and arch length than the normal group.

• The korean journal of orthodontics
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• v.26 no.5 s.58
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• pp.535-546
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• 1996

The purpose of this study was to classify mandibular dental arch forms based on Raberin's method, and to compare Raberin's arch forms with that of the Korean's, and to designate arch form of bracket level according to distance between cusp tip and buccal surface of bracket level. The sample consisted of 159 mandibular dental casts showing normal occlusion which was taken from 62 males and 97 females of the Korean, aging from 13 to 25 years. The model was taken by X-ray. The landmarks were cusp points which expressed the mandibular dental arch line of cusp tips and buccal points which were measured from cusp tips to buccal surfaces of bracket level. The landmarks on the film were digitized, and measurements and statistics were performed. The results were as follows; 1. The models were classified as type 1, type 2, type 3, type 4 and type 5 by the author, and polynomial functions of the six degree and R-square values were calculated using statistical method, and each calculated equations explained each group with the least R-square value of 0.97, and each arch forms' were plotted. 2. The distribution of type 1 was $17.6\%$, type 2 $20.8\%$, type 3 $20.8\%$, type 4 $16.3\%$ and type 5 $24.5\%$. 3. The Korean arch form was characterized by larger width, smaller height compared to the French arch form. 4. The designated arch form of bracket level, viz the distance between cusp point and buccal point was calculated. The distance between cusp point and buccal point of incisor was 1mm, canine 1.9mm, first premolar 2.5mm, second premolar 2.6mm, first molar 2.7mm and second molar 2.7mm.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.2
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• pp.322-328
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• 2007

The first molar is important for mastication and also it plays roles to formation of vertical occlusion and growth of jaw bone after mixed dentition. Impaction of mandibular first molar can result in a short lower facial height, formation of a follicular cyst, pericoronal inflammation, resorption of the roots of neighboring teeth and malocclusion. The options of treatment plans are as follows; observation, surgical exposure, orthodontic traction, surgical relocation and extraction. Surgical exposure could be considered as a basic treatment plan. For surgical exposure it is important to maintain patent channel between the crown and the normal eruptive path into the oral cavity, many techniques including cementation of a celluloid crown, packing with zinc oxide-eugenol surgical pack are used. In these cases, we could observe spontaneous eruption of mandibular first molar using surgical exposure with or without removal of odontoma. Also we could obtain the main patency effectively and conveniently by using surgical pack and translucent retainer.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.4
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• pp.607-617
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• 2002

The purposes of this study were to evaluate the timing of tooth calcification and the change of tooth position with tooth developmental stage on the mandibular teeth. Seven hundred seventy two children(male:446, female:326), 3 to 12 years of age were examined radiographically with panoramic film. Dental development was determined by inspecting radiographs and assigning a rating according to consecutive stages defined by Moorrees, and tooth cusp position and root terminus position were measured from the lower border of mandibular body and calculated the position index to evaluate the movement of tooth with developmental stage. The results were as follows. 1. There were no significant differences between boys and girls in the timing of calcification until crown completion, but timing of calcification tend to be faster in girls than in boys after root initiation stage. 2. In terms of mean age, crown completion of central incisor in boys and girls occurred at the age of 3.71, 4.05 years, at 4.44, 4.60 years for the lateral incisor, at 5.35, 5.11 years for the canine, at 6.62, 6.36 years for the first premolar, at 7.36, 7.17 years of second premolar, at 3.51, 3.69 years of first molar, and at 7.90, 7.64 years for the second molar respectively. Apex 1/2 closed stage of central incisor occurred at the age of 8.70 in boys, 8.18 in girls, at 9.55, 8.99 years for the lateral incisor, at 12.48, 11.60 years for the canine, at 12.30, 12.01 years for the first premolar, at 12.19, 12.26 years of second premolar, at 9.12, 8.87 years of first molar, and at 12.59, 12.45 years for the second molar respectively. 3. There was no noticeable movement of cusp tip until crown completion (Crc), but showed rapid movement toward occlusion plane after root initiation(Ri) and again maintain stable position after root completion stage(Rc). 4. Root terminus position was stable until root 1/4 formation stage(R1/4), followed by rapid movement toward occlusal plane and was stable again after root 3/4 formation stage(R3/4). 5. Developmental stage at the time of alveolar bone penetration by cusp tip varied with each of the permanent teeth. 6. Canine tooth follicle was at the lowest position in the mandibular body during the early stage of calcification, followed by second premolar, first premolar, lateral incisor, second molar, first molar and central incisor in order.

• 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.39 no.5
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• pp.300-309
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• 2009

Objective: The purpose of this study was to evaluate the correlation between menton deviation and dental compensation in facial asymmetry. Methods: Tooth axis and distance of first molar and canine to the reference plane were investigated by cone-beam computerized tomography. The subjects consisted of 50 patients with asymmetric mandibles (male 21, female 29, mean age 24.3 years). Control groups were also assessed (male 11, female 9, mean age 25.6 years). Nine measurements (5 linear measurements and 4 angular measurements) were measured in order to evaluate the correlation between menton deviation and the linear and angular difference of first molar and canine in the deviated and none-deviated sides using the defined MPR images. The differences between deviated and non-deviated side, according to menton deviation, were statistically analyzed using stepwise multiple regression analysis. Results: From the result, Menton deviation was negatively correlated with mandibular first molar's angular measurement (${\Delta\angle}LM6$-Mn plane (dev.-ndev.)) and positively with maxillary fist molar's angular measurement (${\Delta\angle}UM6$-FH plane (dev.-ndev.)) (p < 0.01). Two angular measurements (${\Delta\angle}LM6$-Mn plane (dev.-ndev.), ${\Delta\angle}UM6$-FH plane (dev.-ndev.)) explained the variability in menton deviation with a significant $r^2$ value of 0.589. Conclusions: This study suggests that the tooth axis of upper and lower first molars leans towards the deviated side of Menton when there is mandibular asymmetry with Menton deviation.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.4
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• pp.519-525
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• 2010

Ectopic eruption means the eruption of the tooth in an abnormal position due to multiple factors, which found most frequently in maxillary fist permanent molars, mandibular lateral incisors and maxillary permanent canines. Ectopic eruption of the maxillary first permanent molar occurs when the molar erupts with a more mesial angulation than normal, and locks itself in an atypical resorption on the distobuccal root of the second primary molar. The maxillary first permanent molar plays important roles for mastication and occlusion, so ectopically erupted maxillary first permanent molars should be relocated into proper position. Treatment options are separation by insertion of the brass wire or elastic rings, preparation of distal aspect of the maxillary second primary molar, using fixed or removable appliance with finger spring, and placement of space maintainer or space regainer after extraction of the maxillary second primary molar. We report three cases treated of ectopically erupted maxillary first permanent molar by re-setting of stainless steel crowns, placement of brass wire and using active plate. We could find out distal movement of maxillary first permanent molars into proper position and normal occlusion.