Determination of final occlusal vertical dimension by cephalometric analysis

Resumo

Most of techniques for determining the occlusal
vertical dimension (OVD) of edentulous patients are based on
soft tissues references, which lead to measurement discrepancies.
Objective: To propose a method to obtain the OVD of edentulous
patients during the confection of complete dentures considering
the lower facial height established by Ricketts (LFHr) or the lower
facial height obtained from cephalometric analysis of dentulous
patients (LFHd). Material and methods: The OVD of 11 edentulous
patients was determined by the association of 3 clinical methods. On
each patient’s bite plates a metallic ball was fixed and the patient
was submitted to lateral radiographic to obtain the lower facial
height (LFHe) from cephalometric analysis. Additionally, from 40
lateral cephalograms of dentulous patients the LFHd was obtained.
After that, the distance between metallic balls (DMB, in mm) was
calculated to verify the linear difference when LFHe was changed
to LFHd or LFHr, which provided the amount of wax to be added
or removed from the bite plates, establishing a new method of OVD
determination. LFHe, LFHd and LFHr values were submitted to t e
z statistical tests and DMB differences were analyzed by Student’s
t-test (α=0.05). Results: LFHr (47.0±4.0o a) was statistically higher than LFHd (44.9±5.6o b) and LFHe (43.5±3.5o b). There was statistical
difference on linear discrepancies calculated between the LFHe
and LFHd (1.7±4.1mm a
) or LFHr (4.2±4.1mm b
). Conclusion: The
use of the cephalometric analysis showed to be a useful auxiliary
tool in determining the intermaxillary relationship. However, this
method must be associated with different clinical methods of OVD
determination and it is recommended that regional references are
used to calculate the linear discrepancies.