• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.3
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• pp.312-319
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• 2020

Precocious puberty (PP) is defined as the early development of secondary sexual characteristics (before the ages of 8 years in girls and 9 years in boys). The aim of this study is to identify characteristics of the dental maturity in girls with PP that discriminate them from normal healthy girls. This study included 99 girls aged 6 - 8 years with PP and 99 girls without past medical history of same chronological age (control group). The study was performed on 198 panoramic radiographs (99 PP girls, 99 control group girls). Demirjian method was used to evaluate the panoramic radiographs and determine dental maturity. Difference in dental maturity score and tooth formation stages between the two groups were analyzed. The PP group showed significant higher maturity score than control group. Among mandibular teeth, mandibular 2nd premolar and 2nd molar were significantly more mature in the PP group than control group. Logistic regression analysis showed that mandibular 2nd molar was only significant predictor for PP girls.

• Journal of the korean academy of Pediatric Dentistry
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• v.38 no.2
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• pp.119-128
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• 2011

In the process of assessing the children with anterior crossbite in early mixed dentition, it has frequently been detected that the stronger the skeletal pattern of the malocclusion is, the more markedly delayed the development and eruption of maxillary teeth are. If the anteroposterior characteristics of craniofacial skeleton has any relationship with dental maturation, the evaluation of dental development and eruption was thought to be able to contribute to early diagnosis of crossbite in children. This study was performed for the purpose of elucidating the relationship between dental maturation of maxillary teeth and some cephalometric values in children with anterior crossbite of maxillary undergrowth type in early mixed dentition. Among the children in Hellman dental age IIA and IIC who attended the Pediatric Dental Clinic of Pusan National University Hospital with orthodontic problems, cases with Class III malocclusion were classified and 50 cases of maxillary undergrowth type and type with normal maxilla respectively were randomly selected and studied as subjects. From their lateral cephalographs and panoramic radiographs, their anteroposterior skeletal features, the dental maturity and eruption rate were obtained of each group and data were analyzed to yield the results as follows: 1. Comparing the maturity of maxillary teeth of both groups, only the first molars of maxillary undergrowth group showed significantly slower development and eruption (p<0.05). 2. There was high correlation between maturation of maxillary 1st molar and chronological age(p<0.05). 3. Among the parameters of anteroposterior relationship of skeletal pattern in maxilla and mandible. Wits was revealed as a useful index to predict both the calcification and eruption rate of the 1st molars whereas SNA was to eruption rate(p<0.05).

• The korean journal of orthodontics
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• v.27 no.5 s.64
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• pp.853-864
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• 1997

The evaluation of growth potency can be done with many physiologic indicators. It has been well known that skeletal maturity has a close relation with both sexual maturity and somatic maturity, but the correlation between skeletal maturity and dental maturity was believed to be less certain. But, recent studies show that specific teeth, including lower canines, present close correlations with skeletal maturity. So, in this study, we studied hand-wrist X-ray films and orthopantomograms of 387 Korean boys and girls aged from 7 to 15; the purpose was to determine skeletal and dental maturity, and to find out a new method to estimate individual skeletal maturity using multiple-regression model, without the help of hand-wrist X-ray film. As a result of this study, followings were observed. 1. The following multiple-regression model can estimate skeletal maturity index (SMI) with 84% of accuracy, and regression coefficient of chronologic age, sex and lower canine show statistical significance. SMI = 0.60 x chronologic age - 1.67 x sex$^{**}$ + 0.88 x lower canine$^{*}$ - 0.05 x lower 2nd molar$^{*}$ - 10.3 $^{*}$ : mean age corresponding each developing stage, $^{**}$ : male=1, femal=0 2. The following multiple-regression model can estimate skeletal age with 87% of accuracy, and regression coefficient of chronologic age, sex and lower canine show statistical significance. Skeletal age = 0.75 x chronologic age - 0.55 x sex$^{**}$ + 0.71 x lower canine$^{*}$ - 0.09 x lower 2nd molar* -5.77 $^{*}$ : mean age corresponding each developing stage, $^{**}$ : male=1, femal=0

• Journal of Dental Rehabilitation and Applied Science
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• v.39 no.1
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• pp.52-60
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• 2023

Autotransplantation of third molars with completely formed roots is known to be effective and provide a high long-term success rate. However, in case of severe mobility or unexpectedly extraction is observed during the monitoring period after surgery, it is generally considered as a failure. This case report describes successful replantation of autotransplanted mature third molar into surgically created molar socket. 1 year follow up of transplanted tooth showed clinically normal periodontal pocket depth and tooth mobility. Root resorption or bone loss were not observed. Provided that there is no apparent sign of inflammation, re-insertion into socket is a viable alternative to immediate determination of extraction.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.4
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• pp.718-724
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• 2008

Tooth impaction is a frequently observed eruption anomaly in pediatric dental practice. Young patients with impacted or unerupted teeth have more prediction for dentigerous cyst formation. Dentigerous cyst presents radiographic features, unilocular or multilocular radioluscency. Cysts occur most frequently in the premolar region except third molar. Dentigerous cysts can grow to a considerable size, and large cysts may be associated with a painless expansion of the bone in the involved area. Extensive lesions may result in facial asymmetry, osseous destruction, root resorption of proximal teeth and displacement of associated tooth. The nature of the causative tooth influences the type of surgical treatment required for the dentigerous cyst. If the cyst is associated with a supernumerary or wisdom tooth, complete enucleation of the cyst along with extraction of tooth may be the first treatment choice. Otherwise, preservation of the associated teeth should be considered to prevent a young patient from psychological and mental trauma because of the loss of tooth. We should consider the degree of tooth displacement, osseous destruction and growth pattern of oromaxillofacial area when planning treatment. Thus a proper and logical treatment planning can help a proper growth and development of oromaxillofacial area and can save the patient from a psychological and mental trauma. This report describes 4 cases of the management of impacted premolars and molars associated with dentigerous cysts in children.

• Journal of dental hygiene science
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• v.8 no.2
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• pp.89-96
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• 2008

Effects of sodium fluoride exposure on the amelogenesis during fetal formation were investigated using 11 days rat incisor of control group and two experimental groups. According to results of morphological analysis using an electron microscope, enamel organ in the rat incisor consisted of presecretory, secretory, and maturation zone, especially maturation zone had ruffle-ended ameloblasts (rAB) that additionally supply inorganic ions and smooth-ended ameloblasts (sAB) that remove water and organic compounds. Such a histological composition was same in fetal and adult rats. According to experimental results using calcein (green fluorescence) in order to reveal the modulation cycle of ameloblast, modulation cycle of experimental group decreased on an average one time than control group, as increase of density of sodium fluoride indicated that thickness of smooth-ended ameloblast decreased. Also ratio of thickness on sagittal total length of sAB increased than rAB in experimental groups than control group. In total length of teeth, an injected 100 ppm sodium fluoride group was similar control group but as injected 200 ppm group became short. In experimental group, thickness of sAB and rAB became narrow to the tip of cutting edge. According to concentration of sodium fluoride grows, the modulation cycle and total length of teeth were decreased, finally it prevented teeth growth.

• Journal of the korean academy of Pediatric Dentistry
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• v.40 no.1
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• pp.21-27
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• 2013

In growing children it is frequently found that dental maturation is strongly influenced by the growth rate of maxilla or mandible. If there is evidence to prove this, it might be utilized as a criterion in the early diagnosis of skeletal malocclusion, even before the object's real skeletal features are yet revealed. The purpose of this study was to find out if the difference of dental maturation in over-grown mandible in children with skeletal Class III has any relationship with some skeletal features of mandible. 50 patients in Hellman dental age IIIA with normal occlusion and Class III malocclusion of mandibular over-growth type respectively were selected as study objects. The age estimation was performed on maxillary and mandibular teeth, eruption rate of the 2nd molars of each group have been measured on panoramic radiography, and the differences in dental age of the upper and lower jaw were analyzed under Demirijian's method. The results were as follows: The difference of dental age of maxillary and mandibular teeth between the two groups was 0.66 and 1.20 years respectively, with a higher difference in the experimental group (p < 0.05). The difference of eruption rate of the maxillary and mandibular second molar was not found between two group (p >0.05).

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.3
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• pp.359-366
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• 2010

It was easy to find that children of a skeletal anterior crossbite in the early mixed dentition period showed a stark difference in the dental maturity between their maxillary and mandibular teeth, if they have stronger physical characteristics. If the difference of dental age between maxillary and mandibular teeth which can be identified via panoramic radiographs may serve as an early sign of class III malocclusion, this is considered valuable as a tool of early detection diagnosis. We obtained lateral cephalometric radiographs, panoramic radiographs, working model and clinical images of patients of Hellman dental age IIA and IIC who visited the department of pediatric dentistry, Pusan National University Dental Hospital and examined them to select 50 patents for normal occlusion group and skeletal anterior crossbite group, respectively. Their panoramic radiographs were used for the Demirjian's method to figure out dental ages of maxillary and mandibular teeth of each group and the eruption rate of the first molars. Their differences are as follows: 1. In both groups, the dental ages from Demirjian's method were advanced than the chronological ages. No sexual dimorphism was detected for the chronological or dental age in either group (p>0.05). 2. The difference of dental age of maxillary and mandibular teeth between the normal occlusion group and crossbite group was 0.22 and 0.69 years, respectively, with a higher difference in crossbite group(p<0.05). 3. Compared to the normal occlusion group, the crossbite group showed a higher difference in the eruption rate between maxillary and mandibular first molar(p<0.05).

• Journal of the korean academy of Pediatric Dentistry
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• v.49 no.1
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• pp.35-44
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• 2022

The aim of this study is to evaluate the development of the left mandibular third-molar development with modified Demirjian method and its relation to chronological age. A total of 1653 digital panoramic radiographs of healthy individuals aged between 7 and 23 years who visited Yonsei University Dental hospital were selected. The developmental status of the left mandibular third molars was assessed using dental maturity scoring proposed by Demirjian et al. The mean age of the first appearance of mineralization, complete crown formation, and complete root formation were around 9, 14, 21 years respectively. Statistically significant differences between males and females in the development stage of D and G were revealed that crown formation and root length completion were attained earlier in males than in females. There was significant positive relationship between age and third molar development in both sexes, and new formula was presented to estimate age of children and adolescents based on their developmental stages of third molars. In this study, the use of left mandibular third molar as a developmental marker is appropriate, and age estimation can be attained with dental maturity stage.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.3
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• pp.254-263
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• 2016

Many studies on the prognosis of avulsed teeth were published but follow-up studies on Korean children and adolescents are insufficient. The aim of this study was to identify clinical factors determining the healing and prognosis of permanent incisors that were replanted after avulsion injury. This study included 184 permanent teeth in 142 patients aged 6-14 years. The clinical and radiographic data of the patients were analyzed from electronic medical records. Immature teeth had a higher probability of pulp revascularization than mature teeth. When extra-alveolar time was longer than 60 minutes, the incidence of inflammatory root resorption (IRR) was higher in immature teeth than mature teeth. However, the incidence of replacement root resorption (RR) was higher in mature teeth than immature teeth under the same condition. The incidence of IRR was increased when pulp was extirpated more than 20 days after replantation. IRR had a more significant influence on the decrease of survival expectation than RR. There was no significant correlation between the root development stage and survival expectation. However, when RR occurred, immature teeth survived shorter than mature teeth. Long term follow-up results from this study are expected to be used as fundamental data for the treatment guidelines and evaluation of the prognosis of replanted teeth.