Prosthodontist’s ability to detect parallelism of two lines used in occlusal plane determination

Abstract

ABSTRACT
Background: Prosthodontists estimated the parallelism of the occlusal plane to different anatomical landmarks,
which was somewhat arbitrary and depended mainly on their vision. The aim of this research was to assess the
degree of accuracy of prosthodontists in determining the parallelism of two lines. This research was aimed to assess
which technique would be more accurate for the prosthodontist to distinguish parallelism; the comparison of the
occlusal plane with the interpupillary line or with the inferior border of the earlobes.
Materials and methods: Twenty eight prosthodontic specialists were included in this research. Illustrations of two lines
with different tilts were presented to the participants to distinguish whether parallel or not. These illustrations were
divided into two groups; the first group was with lines close together, used with the earlobes and occlusal plane, and
the second group was with lines farther apart, used for the interpupillary line and occlusal plane.
Results: Prosthodontists were accurate to a fraction of a degree in detecting non-parallel lines. Lines closer together
were evaluated more accurately than lines farther apart. Males were slightly better when the lines were closer
together. Age, experience, and post graduate degrees didn’t seem to play any role in the judgment of the
prosthodontist.
Conclusion: Prosthodontists were very accurate and reliable in judging parallel lines. Concerning the comparison of
parallel lines, earlobes were better landmarks for orienting the occlusal plane than the interpupillary line.
Key words: Prosthodontist, parallel, occlusal, earlobes, interpupillary. (J Bagh Coll Dentistry 2010;22(2):16-21).