Alveolar bone loss of maxillary anterior teeth in adult orthodontic patients

The purpose of this study was to evaluate prevalence and severity of alveolar bone loss in adult orthodontic patients, and to identify risk factors for such bone loss. Standardized periapical radiographs of maxillary anterior teeth and cephalograms made before (T-1) and after (T-2) treatment and treatment charts of 343 adults aged 20.0 to 70.1 years (mean 34.5, SD 9.0) before treatment, representing groups of consecutively treated patients from four orthodontic practices, were examined. Alveolar bone loss was calculated by subtracting the distance from the cementoenamel junction (CEJ) to the alveolar crest (AC) at each interproximal tooth surface from the mesial of one maxillary canine to the mesial of the other. Changes in bone level were calculated by subtracting the distance CEJ-AC at T-1 from the corresponding distance at T-2. Tooth movement was calculated from measurements of superimposed tracings of pretreatment and posttreatment cephalograms. Hygiene level was scored subjectively as adequate or inadequate on the basis of gingival appearance on posttreatment intraoral color slides. Sample means of averaged bone loss of all six anterior teeth and of the surface with the most severe bone loss per patient were 0.54 mm (SD 0.62) and 1.82 mm (SD 1.01), respectively. Only 2.5% of the patients had averaged bone loss of ≥2 mm, whereas 36% of the patients had one or more surfaces with bone loss of ≥2m. Multiple linear regression analyses revealed a positive relationship between age and bone loss, and a negative relationship between initial bone level and subsequent bone loss. No association was found between bone loss and length of treatment, posttreatment gingival appearance, amount of horizontal or vertical tooth movement, or treatment with maxillary osteotomy.