a) In between edentulous space
b) Abutment surface adjacent to an edentulous area
c) Edentulous areas
d) Abutment area
The correct answer is: B. Abutment surface adjacent to an edentulous area.
Guiding planes are surfaces on proximal or lingual surfaces of teeth that are parallel to each other and, more importantly, to the parts of insertions and removal of a removable partial denture. These planes may be created on enamel surfaces or on the surfaces of dental restorations.
The function of guiding planes are as follows:
• To provide one path of placement and removal of restoration.
• To ensure the intended actions of reciprocal, stabilizing and retentive components.
• To eliminate gross food traps between abutment teeth and components of the denture.
As a rule, proximal guiding plane surfaces should be about one half the width of the distance between the tips of adjacent buccal and lingual cusps or about one third of the buccal lingual width of the tooth. They should extend vertically about 2/3rds of the length of enamel crown portion of the tooth from the marginal ridge cervically.