Guiding Planes

Question 1

what are guiding planes

Answer 1

vertically parallel surfaces of abutment teeth oriented so as to contribute to the direction of the path of placement and dislodgement of RPDs

Question 2

guiding planes ____ on natural teeth

Answer 2

rarely exist

Question 3

what are the functions of guiding planes

Answer 3

• provide for one path of placement/ removal
• ensure the intended actions of the RPD components
• eliminate/decrease gross food traps
• increase frictional component of minor connectors
• lowers the hieght of contour on proximal surfaces to allow better positioning of arms

Question 4

how can reduction of the guiding plane be accomplished

Answer 4

altering the tilt of the cast or by selective grinding of the enamel surface

Question 5

what are the locations of guiding planes

Answer 5

• proximal surfaces of abutment teeth
• parallel to long axis of teeth
• as length is increased, frictional retention is increased and resistance to rotation is increased

Question 6

the width of guiding planes:

Answer 6

• as wide as the widest portion of the occlusal rest
• one third of the bucco lingual width of the tooth
• one half the distance between the cusp tips

Question 7

length of guiding planes:

Answer 7

tooth supported abutments- 3.0 - 4.0 mm
- tooth- tissue supported abutments ( distal extension abutments) - 1.5 to 2.0 mm