• 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.

• 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.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.

• The korean journal of orthodontics
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• v.35 no.3 s.110
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• pp.227-237
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• 2005

Eruptive disturbance of the permanent lower first molar is an uncommon condition caused by physical barriers on the eruption path or failure of the eruptive mechanism. Once eruptive disturbance of the permanent lower first molar is diagnosed. treatment should be started as soon as possible to establish a normal eruption pathway and to avoid any detrimental effects on the developing occlusion A case of primary retention of the mandibular first permanent molar treated with operculectomy and forced eruption which showed good treatment results and stability is described

• The korean journal of orthodontics
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• v.46 no.3
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• pp.171-179
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• 2016

Objective: The primary aim of the study was to generate new prediction equations for the estimation of maxillary and mandibular canine and premolar widths based on mandibular incisors and first permanent molar widths. Methods: A total of 2,340 calculations (768 based on the sum of mandibular incisor and first permanent molar widths, and 1,572 based on the maxillary and mandibular canine and premolar widths) were performed, and a digital stereomicroscope was used to derive the the digital models and measurements. Mesiodistal widths of maxillary and mandibular teeth were measured via scanned digital models. Results: There was a strong positive correlation between the estimation of maxillary (r = 0.85994, $r^2=0.7395$) and mandibular (r = 0.8708, $r^2=0.7582$) canine and premolar widths. The intraclass correlation coefficients were statistically significant, and the coefficients were in the strong correlation range, with an average of 0.9. Linear regression analysis was used to establish prediction equations. Prediction equations were developed to estimate maxillary arches based on $Y=15.746+0.602{\times}sum$ of mandibular incisors and mandibular first permanent molar widths (sum of mandibular incisors [SMI] + molars), $Y=18.224+0.540{\times}(SMI+molars)$, and $Y=16.186+0.586{\times}(SMI+molars)$ for both genders, and to estimate mandibular arches the parameters used were $Y=16.391+0.564{\times}(SMI+molars)$, $Y=14.444+0.609{\times}(SMI+molars)$, and $Y=19.915+0.481{\times}(SMI+molars)$. Conclusions: These formulas will be helpful for orthodontic diagnosis and clinical treatment planning during the mixed dentition stage.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.1
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• pp.167-174
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• 2008

Mandibular first molar and primary molars usually have two roots, on the mesial and distal sides. Occasionally, these molars have an extra root located in the distolingual aspect. Prevalence of the 3-rooted first permanent molar shows ethnic variation, ranging from about 3% in Caucasian to about 20% in Mongoloid group, which includes Chinese, Japanese, Eskimo, American and Canadian Indians. The frequency of the mandibular molar with three roots decreases in the order of the first permanent molar, the second primary molar, and the first primary molar. If the mandibular first or second primary molar has an additional distolingual root, the adjacent molars, including the first permanent molar, posterior to it also may have it. Coronal morphologic change can occur in the mandibular first primary molars with three roots: the crown had more triangular-shape compared to the one with two roots, possibly affected by the presence of additional distolingual root. Clinically, exact diagnosis and treatment should be taken with those teeth for pulp canal treatment, extraction, and SS Cr.

• 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)

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.1
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• pp.130-135
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• 2010

Ectopic eruption is caused by an abnormal direction of eruptive path, most common in maxillary first molar, mandibular lateral incisor, and maxillary canine, and sometimes mandibular first molar. Ectopic eruption of first molar leads to abnormal root resorption of second deciduous molar, which, if left untreated, could cause premature loss of second deciduous molar; mesial tilting and rotation of first permanent molar; lack of space for eruption of second premolar; and occlusal problems. Therefore early treatment is advised when diagnosed as ectopic eruption. Treatment of ectopic eruption in the first permanent molar involves providing proper guidance for the direction of eruption using interproximal wedging and distal tipping methods while preserving second deciduous molar. This case report shows satisfactory results of the ectopic eruption of mandibular first molars in young patients who were treated with Humphrey appliance and Halterman appliance.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.2
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• pp.226-232
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• 2010

Incidence of tooth impaction varies from 5.6 to 18.8% of the population. Failure of eruption of the first and second permanent molars is rare; the prevalence in the normal population is 0.01% in case of the first permanent molar, and 0.06% in case of the second permanent molar. Permanent molars are particularly important for providing sufficient occlusal support and co-ordinating facial growth. Failure of eruption of permanent molars may result in various complications such as decrease in vertical dimension, posterior open bite, extrusion of antagonistic teeth, resorption and inclination of adjacent teeth, formation of cyst and so on. Treatment options of impacted teeth are periodic observation, surgical exposure, surgical exposure with subluxation, orthodontic relocation, and surgical extraction before prosthetic treatment. Early diagnosis and treatment are important, because delayed treatment induces various problems such as decreased spontaneous eruptive force, decreased successful percentage, increased treatment period, increased various complications. Prevalence of the failure of mandibular first molars is rare but eruptive guidance before extraction of impacted teeth is necessary due to importance of permanent molars. We reported two cases of surgical exposure of impacted mandibular first molar. In these cases, we could observe different result of the impacted mandibular first molar after surgical exposure.