The European Journal of Orthodontics Advance Access originally published online on November 2, 2005
The European Journal of Orthodontics 2006 28(2):166-172; doi:10.1093/ejo/cji086
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Assessment of open and incomplete bite correction by incisor overlap and optical density of polyvinyl siloxane bite registration
Departments of Orthodontics, * The Maurice and Gabriela Goldschleger, School of Dental Medicine, Tel Aviv University and ** Tel Hashomer IDF, Israel Aviation Medical Center IAF, Israel
Address for correspondence Dr Nir Shpack, Department of Orthodontics, The Maurice and Gabriela Goldschleger, School of Dental Medicine, Tel Aviv University, 69978 Tel Aviv, Israel, E-mail: nshpack{at}post.tau.ac.il
Open bite (OB) is a generalized term, which could incorporate subgroups that react differently to vertical correction. The objectives of the present study were to detect vertical treatment changes in incomplete bite (IB: inter-incisor overlap with no lower incisor contact with teeth or palate) and OB (no inter-incisor overlap) groups compared with a complete bite (CB: inter-incisor overlap with full lower incisor contact with teeth or palate) control group, to evaluate treatment response of the central and lateral incisors, and to study the vertico-sagittal interaction. Dental casts were taken at three time points, pre-treatment, post-treatment, and after one year of retention, from 54 Class II patients (22 males and 32 females with a mean age of 11 years 6 months) divided into three groups: CB (n = 21), IB (n = 18) and OB (n = 15). Measurements included incisor overlap (mm) and optical density (OD/mm2) of occlusal bite registration made of polyvinl siloxane.
Both CB and IB groups demonstrated post-retention bite opening. However, bite opening in the CB group was three times greater than that in the IB group (e.g. lower lateral = –1.42 mm, 118 OD/mm2 versus –0.40 mm, 107 OD/mm2). Conversely, the OB group showed a significant (P < 0.001) bite closure (e.g. lower lateral = 1.30 mm, –377 OD/mm2). Overjet changes affected OD measurements, causing diversity in OD and millimetric measurements of the lateral incisors in the IB group. In conclusion, the OB group demonstrated a significant stable vertical correction; a post-treatment non-contact inter-incisor relationship was determined by a vertico-sagittal relapse; and full compensation of an IB was not possible.