Relationship between formation and eruption of permanent mandibular buccal dentition and vertical height of the mandibular body: longitudinal study of Japanese boys from 4 to 9 years of age.

AIM: To examine the relationship between the formation and eruption (vertical tooth movement in and through the alveolar bone) of the permanent mandibular buccal dentition and vertical height of the mandibular body. METHOD: Mandibular morphology and tooth formation and eruption were analyzed from cephalograms taken annually on each birthday month from 4 to 9 years of age. RESULTS: From 4 to 6 years of age, before active tooth eruption, there was a significant positive correlation between the vertical height of the mandibular body and the distance from the permanent mandibular buccal dentition to the occlusal plane. There was a significant positive correlation between the vertical height of the mandibular body at 6 years of age and the subsequent annual amount of tooth eruption in the mandibular buccal dentition. Simple linear regression equations were obtained to predict the amount of mandibular buccal tooth formation and eruption from the vertical height of the mandibular body at 6 years of age. CONCLUSION: The larger the mandibular vertical height, the larger the distance from the buccal dentition to the occlusal plane before active eruption, and the larger the amount of tooth eruption during the active eruption period. The vertical mandibular morphology is useful to predict the formation and eruption of the mandibular buccal dentition.

Three cases of anterior maxillary osteotomy under orotracheal intubation.

Anterior maxillary osteotomy is frequently applied to skeletal Class II cases with maxillary protrusion. In addition to the anteroposterior problem, these cases are often accompanied with a long midfacial appearance and display of incisors and gingiva during smiling. In the application of anterior maxillary osteotomy to such patients, it is necessary to move the anterior maxillary segments upward as well as backward. Since the upward movement occasionally interferes with the intranasal endotracheal tube, orotracheal intubation is recommended for the operation. Recently, the use of a resin replica of the mandibular dental arch was introduced to place the anterior maxillary segment correctly in the planned position and to obtain the correct occlusion. This article reports on 3 maxillary protrusive skeletal Class II patients with deep overbites and vertical esthetic problems treated by this method. The treatment results show that all 3 patients exhibited large upward and backward movements of the anterior maxillary segments and desirable facial profiles, with a reduction of the deep overbites after the treatment. This case report demonstrates that the anterior maxillary osteotomy under orotracheal intubation with the use of a resin replica is a useful method to treat maxillary protrusive skeletal Class II patients with a large alveolar height.