• Proceedings of the KACD Conference
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• 2001.11a
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• pp.574.1-574
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• 2001

Maxillary first molar, the "6-year molar", is the tooth largest in volume and most complex in root and root canal anatomy. Therefore, maxillary first molar is possibly the most treated, least understood. It is the posterior tooth with the highest endodontic failure rate and unquestionably one of the most important teeth. The earliest permanent posterior tooth to erupt, the mandibular first molar seems to be the most frequently in need of endodontic treatment.(omitted)

• The Journal of Korea Assosiation for Disability and Oral Health
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• v.7 no.1
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• pp.33-37
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• 2011

The ectopic eruption is defined as abnormal eruption which gives to displacement of the teeth and abnormal root resorption of adjacent teeth. The prevalence of ectopic eruption is reported to vary 2~6%, most of them are in the maxilla. Etiologic factors include narrow maxilla, large maxillary teeth, inclined eruption path of the first molar, retruded position of the maxilla and hereditary factor. Irreversible ectopic eruption where the second primary molar is lost often causes mesial tipping and rotation of the permanent molar, unfavorable occlusion and space deficiency for the second premolar. Ectopically erupted teeth should be treated early to maintain normal development of the dentition, harmony of facial growth and occlusal support. The method of the treatment are classified as follows : appliances that is positioned at the contact point for unlocking and the distal movement, fixed appliance that is connected to more than one tooth, and occlusion guiding method after disking or extraction of the second deciduous molar. A case report of a patient with bilaterally ectopic eruption of maxilla and mandible first permanent molar was present. Also, the patient who had experienced the chronic myelogenous leukemia, show various dental developmental complications. The ectopic eruption was treated with a Halterman appliance that was a effective way of correcting of ectopic eruption of the permanent first molar.

• Journal of the Korean Academy of Pediatric Dentistry
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• v.51 no.1
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• pp.11-21
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• 2024

This study aimed to analyze the prevalence and severity of infraoccluded primary molars (IPM) and their correlation with the agenesis of permanent successors (APS). A total of 4,011 panoramic radiographs from children aged 4 to 11 years who had all 8 primary molars were examined. The prevalence of APS was analyzed based on the severity and tooth type of IPM. The prevalence of IPM was 13.0%, and there was no difference between genders. The majority of the children had two IPMs each. In all tooth types, mild infraocclusion was the most prevalent, whereas severe infraocclusion was the least frequent. Among the types of primary molars, the lower primary first molar (62.3%) was the most affected, followed by the lower primary second molar (27.7%), the upper primary second molar (5.8%), and the upper primary first molar (4.2%). Infraocclusion was 11.2 times more prevalent in the mandible than in the maxilla, with no significant difference between the left and right sides. The correlation between IPM and APS was also investigated. Among the subjects, 177 had one or more agenesis of premolars, of whom 54 (30.5%) had IPM. Additionally, among the 521 individuals with IPM, 54 individuals exhibited APS (10.4%). This study identified a noteworthy prevalence of infraocclusion, with notable variations among molar types. The LPFM was particularly affected. The majority of cases were classified as mild in severity. Furthermore, a compelling association between IPM and APS was established. Understanding this connection may enhance treatment strategies for infraoccluded teeth and tooth agenesis.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.26 no.2
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• pp.181-189
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• 1996

Ameloblastic odontoma is a mixed odontogenic tumor, which is characterized as being extremely rare, displaying aggressive clinical behavior, resembling a mixed radiopaque and radiolucent radiographic appearance and containing both ameloblastoma and a composite odontoma. Seven-year-old boy complaining of delayed eruption of the left lower permanent 1st molar came to the department of Oral & Maxillofacial Radiology at Chonbuk National University Hospital. The list of our radiographic differential diagnosis included the dental follicle, compound odontoma, complex odontoma and cystic odontoma. The microscopic analysis showed the lesion with the characteristics of an ameloblastic odontoma. The obtained results were as follows; 1. The area was asymptomatic, but the delayed eruption of the left lower permanent 1st molar was observed. Radiographically, well-defined widened pericoronal radiolucency containing several tooth-like radiopacities involving the impacted left lower permanent 1st molar and well-defined round radiolucency containing irregular radiopaque mass were observed. 3. Histopathologically, several tooth-like structures, odontoma components with the area of typical enamel, dentin and pulp, and ameloblastic components with typical follicular ameloblastoma were observed.

• Journal of the Korean Academy of Pediatric Dentistry
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• v.36 no.2
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• pp.253-261
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• 2009

The purpose of this study was to present new data on the timing and sequence of permanent teeth emergence and to compare these findings with the results of earlier studies. The dental examinations had been performed to E-elementary school students, who visited the Yonsei University Dental Hospital between 1998 and 2005; 1,307 boys and 1,312 girls with the age ranging from 6 to 12 years old. The followings were concluded. 1. Eruption time of the maxillary permanent teeth is as follows. It was 6.81 years in male and 6.73 years in female for the central incisor, 7.78 years in male and 7.65 years in female for the lateral incisor, 10.48 years in male and 9.92 years in female for the canine, 9.76 years in male and 9.63 years in female for the first premolar, 10.66 years in male and 10.49 years in female for the second premolar, 6.39 years in male and 6.26 years in female for the first permanent molar, and 12.13 years in male and 12.03 years in female for the second permanent molar. 2. Eruption time of the mandibular permanent teeth is as follows. The central incisor could not be determined in this study, but it is assumed to erupt before the age of 6.08. In the mandible, eruption time was 6.78 years in male and 6.65 years in female for the lateral incisor, 9.76 years in male and 9.05 years in female for the canine, 9.82 years in male and 9.59 years in female for the first premolar, 10.67 years in male and 10.52 years in female for the second premolar, 6.22 years in male and 6.12 years in female for the first permanent molar, and 11.58 years in male and 11.14 years in female for the second permanent molar. 3. The eruption sequence is as follows. In the maxilla, the first permanent molar erupted first, followed by the central incisor, the lateral incisor, the first premolar, the canine, the second premolar, and the second permanent molar. In the mandible, the central incisor erupted first, followed by the first permanent molar, the lateral incisor, the canine, the first premolar, the second premolar, and the second permanent molar. 4. Tooth eruption occurred earlier in female compared to male by average of 0.19 year in the maxilla and 0.29 year in the mandible. 5. In both male and female, the hiatus (interval of rest) occurred between the emergence of lateral incisor and first premolar in the maxilla while it was observed between the lateral incisor and canine in the mandible. Male had a hiatus of 1.98 years in the maxilla and 2.90 years in the mandible, while the female's were 1.98 years and 2.40 years, respectively.

• Journal of Technologic Dentistry
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• v.8 no.1
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• pp.91-99
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• 1986

In order to evaluate the community dental health level the actual health capacity of the lower-first permanent molar is suitable as a indicator for assessment. So we had surveyed decayed, missed and filled lower permanent first molar of 460 persons who were in the age from 20 to 29 in Iri City. The obtained results were as follows: 1. The DMFT indices of the lower first permancent molars showed in 1.40 in the age group of from 20 to 24 and 1.44 from 25 to 29. 2. The actual dental health capscities of the lower first permanent molars showed in 84.86% in the age group of from 20 to 24 and 81.03% from 25 to 29. 3. The DMF indices of the lower first permanent molars showed 15.15% in the age group of from 20 to 24 and 18.98% of from 25 to 29. 4. The DMF rates of the lower first permanent molars showed 85.66% in the age group of from 20 to 24 and 88.70% of from 25 to 29. 5. The DMF rates of the lower first permanent molars showed 70.00% in the age group of from 20 to 24 and 71.96% of from 25 to 29. 6. The DT rates of the lower first permanent molars showed 48.84% in the age group of from 20 to 24 and 39.55% of from 25 to 29. 7. The FT rates the lower first permanent molars showed 40.22% in the age group of from 20 to 24 and 43.98% of from 25 to 29. 8. The MT rates of the lower first permanent molars showed 10.94% in the age group of from 20 to 24 and 16.17% of from 25 to 29.

• Journal of the Korean Academy of Pediatric Dentistry
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• v.44 no.1
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• pp.56-63
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• 2017

Delayed eruption of the first molar, without a generalized or localized cause, is usually associated with delayed development of the affected tooth. The aim of this study was to investigate the clinical features of the first permanent molar showing delayed development and eruption, and its association with developmental anomalies of other teeth. Panoramic radiographs of 40 healthy children showing delayed development and eruption of first permanent molars were analyzed. The clinical features of affected first molars and developmental anomalies of other teeth (except third molars) were evaluated. Delayed first molars were more frequent in the maxilla. The incidence of bilateral delayed development of first molars was greater than that of unilateral cases in female patients. In contrast, male patients showed unilateral delayed development of the first molar more frequently. A higher incidence of congenitally missing teeth was observed in patients with delayed first molar. In each case, delayed development or congenital absence was observed in the second molar adjacent to the delayed first molar. Overall, delayed first molar seems to be associated with congenital absence of additional teeth. Understanding the developmental mechanisms of this phenomenon requires further studies.

• Journal of the Korean Academy of Pediatric Dentistry
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• v.46 no.1
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• pp.10-20
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• 2019

Individual dental age is used as an index of chronological age estimation and is an important indicator of the child's growth stage. Dental age does change greatly over time, but it changes constantly. And updating information about this change is important. The purpose of this study was to provide information about tooth eruption stage using diagnostic model analysis and to investigate tooth eruption sequence and estimate chronological age based on this information. Tooth eruption stages were measured on a diagnostic model from 488 patients in 5 - 13 year old children. Based on the information on eruption stage, eruption sequence in maxilla was first permanent molar, central incisor, lateral incisor, first premolar, canine, second premolar and second permanent molar. Eruption sequence in mandible was first permanent molar, central incisor, lateral incisor, canine, first premolar, second premolar and second permanent molar. There were significant differences between males and females in the eruption stage of canine, first and second premolar, and second molar at several ages. The chronological age of male and female was estimated by the coefficient of determination of 0.816, 0.826 respectively.

• Journal of the Korean Academy of Pediatric Dentistry
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• v.49 no.1
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• pp.45-56
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• 2022

The purpose of this study is to evaluate changes of occlusion following the placement of preformed metal crown in the permanent first molar affected by severe caries or hypomineralization. The study was conducted on 24 patients who met the criteria among the patients with occlusion in the permanent first molar reaching the occlusal plane. Restorative treatment was performed on one first molar using preformed metal crown. Before treatment, immediately after treatment, after 4 weeks, and after 8 weeks, the T-scan III was used for measuring distribution of bite force at the maximum intercuspal position, and overbite was measured with digital vernier calipers and change of dental midline was surveyed. After 8 weeks, questionnaires survey was conducted. In most cases, immediately after treatment, the distribution of bite force between the restored side and non-restored side of arch was reversed compared to before treatment, and the overbite was decreased. However, after 4 weeks, bite force of the left and right side was balanced and the distribution of bite force on the restored and non-restored permanent first molars had similar values. Also, the changed overbite and midline were returned to pre-treatment status and there was no significant temporomandibular joint and masticatory discomfort after treatment. In this study, it was confirmed that spontaneous occlusal equilibrium was achieved one month after the placement of preformed metal crown.

• 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.