• Journal of the korean academy of Pediatric Dentistry
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• v.41 no.1
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• pp.64-71
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• 2014

Mesiodens is defined as a supernumerary tooth in the premaxillary region. It can cause several clinical manifestations in normal eruption and position of adjacent teeth, such as displacement and impaction. Although the mesiodens accompanied by a clinical complication is indicated for removal, the optimal time of mesiodens removal is still controversial. Some authors suggest immediate intervention defining the removal of mesiodens as soon as possible after the first detection. On the other hand, others recommend delayed intervention which denotes the removal of mesiodens after complete root development of adjacent teeth. This case report is presented with three cases of spontaneous correction and proper alignment of rotated maxillary central incisors by extraction of mesiodens when the crowns of rotated incisors were completely formed while the roots of them were at an early developmental stage.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.4
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• pp.630-635
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• 2004

The etiology of mesiodens is unknown but the most widely accepted theory is the hyperactivity of the dental lamina. Complications of mesiodens are delayed or prevented eruption of maxillary central incisors, displacement or rotation of permanent teeth, crowding of affected region, abnormal diastema or permanent space closure, dilaceration or abnormal root development of permanent teeth, primordial or follicular cyst formation, root resorption of adjacent teeth, eruption into nasal cavity. If mesiodens rotate the maxillary central incisors, space deficiency is not common and relapse is very common. So overcorrection is needed. To prevent the rotational relapse, early treatment, overcorrection, long retention period, properly formed proximal surface, use of coupled force, and surgical techniques have been suggested. The authors present two cases, whose chief complain were severely rotated maxillary incisors by mesiodens, treated by orthodontic and surgical technique and showed good results.

• The Journal of the Korean dental association
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• v.16 no.11 s.114
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• pp.849-856
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• 1978

Relapse following rotational movement of the tooth is a common problem in orthodontic practice. To overcome such relapse, many procedures have been advocated: prolonged retention, permanent retention, over-rotation, rotation of teeth at an early age, surgical procedures such as gingivectomy, redressement force, septotomy, et cetra. A 23-year-old woman presented with Angle's Class I malocclusion and extreme rotation of maxillary central incisors. After 15 months' active therapy, septotomy was performed on maxillary central incisors and Howley retainer was applicated for the purpose of overcoming rotational relapse. During the 1 year post-operative observation, negligible, if any, rotational relapse occurred.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.3
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• pp.368-373
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• 2010

The incisors function as instruments for biting and cutting food during mastication. They also support the lips and face and maintain vertical dimension. In addition, they contribute to overall normal arch appearance. They play important role during the articulation of speech and assist in guiding jaw closure. Extraction and space maintenance are the most common treatment for a tooth with poor prognosis. However, in the mixed dentition, extraction of the upper permanent incisors results in many complications, such as resorption of alveolar bone, poor esthetics, pronunciation, and mastication. Considering these various roles of incisors in oral cavity, approach for traumatized incisors, even the ones with poor prognosis, should be considered first prior to simple extraction. The dentist must take into account the age of the patient, growth potential, occlusion, oral hygiene status, economic status and motivation towards dental health in addition to patient compliance. In this case, although the prognosis was predicted to be unfavorable due to short root and mobility, we could save the central incisor using conservative treatment, reposition by orthodontic appliance instead of extraction.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.2
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• pp.213-230
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• 2008

The aim of this study was to analyze the initial movement and the stress distribution of each tooth and periodontal ligament during the lingual lever-arm retraction of 6 maxillary incisors using FEA. Two kinds of finite element models were produced: 2-properties model (simple model) and 24-properties model (multi model) according to the material property assignment. The subject was an adult male of 23 years old. The DICOM images through the CT of the patient were converted into the 3D image model of a skull using the Mimics (version 10.11, Materialise's interactive Medical Image Control System, Materialise, Belgium). After series of calculating, remeshing, exporting, importing process and volume mesh process was performed, FEA models were produced. FEA models are consisted of maxilla, maxillary central incisor, lateral incisor, canine, periodontal ligaments and lingual traction arm. The boundary conditions fixed the movements of posterior, sagittal and upper part of the model to the directions of X, Y, Z axis respectively. The model was set to be symmetrical to X axis. Through the center of resistance of maxilla complex, a retraction force of 200g was applied horizontally to the occlusal plane. Under this conditions, the initial movements and stress distributions were evaluated by 3D FEA. In the result, the amount of posterior movement was larger in the multi model than in the simple model as well as the amount of vertically rotation. The pattern of the posterior movement in the central incisors and lateral incisors was controlled tipping movement, and the amount was larger than in the canine. But the amount of root movement of the canine was larger than others. The incisor rotated downwardly and the canines upwardly around contact points of lateral incisor and canine in the both models. The values of stress are similar in the both simple and multi model.