Long-term changes in untreated dental arches
Tsiopas N, Nilner M, Bondemark L, Bjerklin K. A 40 years follow-up of dental arch dimensions and incisor irregularity in adults. Eur J Orthod 2011 Oct 19 [Epub ahead of print]
Studies describing 40 years of changes in dental arch dimensions and irregularity are rare. Researchers at Malmo University in Sweden followed 35 patients for an average of 38.4 years. The inclusion criteria were no missing teeth, no history of orthodontic or prosthodontic treatment, and at least 20 years of age at the initial records. They were followed up at 10-year and 30-year time points. The results describe 18 patients included in this study. Mandibular incisor crowding increased, with Little’s irregularity index showing a 1.0-mm average change. No changes were observed in the maxilla. Intercanine distances decreased by 1.1 mm in the mandible and by 0.8 mm in the maxilla. Intermolar widths increased by 0.7 mm in the mandible and remained unchanged in the maxilla. Arch lengths decreased in both the mandible and the maxilla, with an average of 0.7 mm mainly at the first follow-up time point. Arch depths decreased in both the mandible and the maxilla, with similar changes for the molars and the canines. The authors believed that this represented a gradual mesial migration of the dentition. No statistically significant changes were found in overjet, overbite, and frequency of Class I occlusion, Class II occlusion, crossbite, open bite, and deepbite. This study confirms the finding of previous studies (Bishara, 1996; Bishara, 1997; Tibana, 2004). The authors concluded that the dentoalveolar process is dynamic and will continue to experience changes throughout an adult’s lifetime. Both patients and orthodontists should be aware of and expect dentoalveolar changes throughout life.
Reviewed by Michael C. Meru
Effect of intercuspidation on Class II dental correction
Thurman MM, King GJ, Ramsay DS, Wheeler TT, Phillips C. The effect of an anterior biteplate on dental and skeletal Class II correction using headgears: a cephalometric study. Orthod Craniofac Res 2011;14:213-21
Class II malocclusions include many combinations of dental, skeletal, and esthetic problems that usually do not self-correct. Recent studies have suggested that dental intercuspidation might contribute to the maintenance of a Class II malocclusion despite the greater amount of mandibular growth relative to the maxilla during adolescence. These authors hypothesized that separating the dentition during Class II treatment will enhance the correction of the dental Class II relationship. They compared the cephalometric treatment outcomes between 2 groups: Class II subjects treated with headgear alone, and Class II subjects treated with headgear and biteplane to disclude the posterior teeth. Group 1 (University of Florida) included 81 subjects with a minimum of a bilateral end-to-end Class II molar relationship. Treatment consisted of a biteplane worn full time and headgear (16 ounces) worn 14 hours a day until a Class I molar relationship was achieved, up to 24 months. Group 2 (University of North Carolina) included 50 subjects with overjet of 7 mm or greater, treated with a combination headgear at night (8-10 oz) for 15 months. The authors’ main finding was that the biteplane provided no additional benefit to headgear treatment for Class II growth modification. The biteplane’s occlusal separation did not permit greater mandibular growth or greater forward translation of the mandibular dentition. The headgear-biteplane group did show a significantly greater effect on overbite reduction than did the headgear group, confirming that biteplanes are effective for the correction of deep overbites. The analytic challenges of comparing 2 cohorts from 2 separate randomized clinical trials are discussed.
Reviewed by Laura Harshbarger
Effect of intercuspidation on Class II dental correction
Thurman MM, King GJ, Ramsay DS, Wheeler TT, Phillips C. The effect of an anterior biteplate on dental and skeletal Class II correction using headgears: a cephalometric study. Orthod Craniofac Res 2011;14:213-21
Class II malocclusions include many combinations of dental, skeletal, and esthetic problems that usually do not self-correct. Recent studies have suggested that dental intercuspidation might contribute to the maintenance of a Class II malocclusion despite the greater amount of mandibular growth relative to the maxilla during adolescence. These authors hypothesized that separating the dentition during Class II treatment will enhance the correction of the dental Class II relationship. They compared the cephalometric treatment outcomes between 2 groups: Class II subjects treated with headgear alone, and Class II subjects treated with headgear and biteplane to disclude the posterior teeth. Group 1 (University of Florida) included 81 subjects with a minimum of a bilateral end-to-end Class II molar relationship. Treatment consisted of a biteplane worn full time and headgear (16 ounces) worn 14 hours a day until a Class I molar relationship was achieved, up to 24 months. Group 2 (University of North Carolina) included 50 subjects with overjet of 7 mm or greater, treated with a combination headgear at night (8-10 oz) for 15 months. The authors’ main finding was that the biteplane provided no additional benefit to headgear treatment for Class II growth modification. The biteplane’s occlusal separation did not permit greater mandibular growth or greater forward translation of the mandibular dentition. The headgear-biteplane group did show a significantly greater effect on overbite reduction than did the headgear group, confirming that biteplanes are effective for the correction of deep overbites. The analytic challenges of comparing 2 cohorts from 2 separate randomized clinical trials are discussed.
Reviewed by Laura Harshbarger
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