• Journal of the korean academy of Pediatric Dentistry
• /
• v.37 no.1
• /
• pp.117-123
• /
• 2010

Tooth eruption is the movement of the tooth from the developing place in the alveolar bone to the functional position in the oral cavity. The permanent incisors originate from the dental lamina on the lingual side of preceding deciduous tooth and erupt to the level of the occlusion through the well developed gubernacular cord. Ectopic eruption is a developmental disturbance in the eruption pattern of the permanent dentition. Most of the ectopically erupted lower incisor has been found in lingual side. The ectopically erupted tooth could be repositioned by orthodontic force in the early mixed dentition, which could help preventing the problems of loss of space and the lingual tilting of the lower anterior teeth. An eight-year-old girl visited the department of pediatric dentistry, Yonsei Dental University Hospital, for the evaluation and the treatment of the lower right lateral incisor, which was horizontally erupted in the lingual side, parallel to the mouth floor. Her tongue was placed on the labial side of that tooth. There was no previous dental history of dental caries or trauma on the pre-occupied primary incisor. Clinical and radiographic examinations including the computed tomography(CT), showed no evidence of dilacerations on root. Therefore, we decided to start active orthodontic traction of the lower right lateral incisor. We designed the fixed type of buccal arch wire and the lip bumper with hook for the traction. Button was attached to the lingual side of the ectopically positioned tooth. Elastic was used between the appliance and the button on that tooth. After the tooth become upright over the tongue level, appliance was change to the removable type and periodic check-up with occlusal guidance was followed to monitor the position of the tooth. In this case using the fixed appliance with modified form of lip bumper and hook embedded in acrylic part instead of extraction was very efficient up-righting the ectopically erupted tooth toward the occlusal plane.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.27 no.3
• /
• pp.317-326
• /
• 2011

The mental foramen and anterior loop of the mandibular canal are important landmarks for mandibular surgical procedures. The purpose of this study was to analyze the shape and position of the mental foramen and anterior loop of the mandibular canal on the computed tomography (CT) images, and apply the results clinically. CT images of 96 patients (33 male, 36 female, age range 17~43 years, mean $24.6{\pm}4.99$ years) were enrolled. The horizontal and vertical position of the mental foramen, as well as the distance from the root apices were measured. The distance of the anterior loop of the mandibular canal to the root apices, and the buccal angle were measured. The mental foramen was found mostly below the second premolar observed in 81 cases (46.0%), between the first and second premolars in 67 cases (38.0%), and between the second premolar and first molar in 19 cases (10.2%). The mean distance between the mental foramen and the lower border of the mandible was $12.20{\pm}1.77$ mm, the mean distance between the mental foramen and root apex was $5.16{\pm}0.98$ mm. The mean distance of the anterior loop of the mandibular canal was $5.80{\pm}2.00$ mm. The buccal angle measured at $47.7{\pm}9.07^{\circ}$. The distance between the root apex and mental foramen measured as $5.16{\pm}0.98$ mm on panoramic radiography, and $6.2{\pm}3.07$ mm on CT. The mean distance between the mental foramen and mandibular canal was $5.39{\pm}1.62$ mm. When performing surgical procedures such as installing dental implants, it is important to minimize surgical trauma, especially the risk of damage to the mental nerve. To optimize the surgical outcome, a careful assessment of the shape and position of the mental foramen and the anterior loop of the mandibular canal must be made. CT images are useful for finding such anatomic structures.