Supraposition of unopposed molars in young and adult rats

ObjectivePrevious clinical studies indicate that the overeruption of unopposed teeth may be different between young and adult individuals. The aim of this study was to investigate the position of the unopposed molar, in young and adult rats.MethodsIn young (4-week old) and adult (26-week old) rats, the right maxillary molar crowns were reduced occlusally by grinding. After 4 weeks, the animals were sacrificed and scanned by micro-CT.ResultsThe unopposed molars of the young animals were in supraposition being on average 262 μm (±135 μm) higher than the position of molars with antagonists. This was more pronounced than in adults (average 125 ± 108 μm, P < 0.01). In the young animals the alveolar bone level was higher in the unopposed molars with supraposition while no differences were found in the adults’ molars.ConclusionsOur results demonstrated that the overeruption potential of unopposed molars is higher in young than adult rats.