My understanding was that guideplanes only extend to the line angles on the facial and lingual surfaces. May you please help me understand why the bur is running across the entire facial and lingual surfaces in this video? Thank you
I think that's only for proximal guiding plates. In this case he's got a retentive clasp on the buccal and reciprocal arm on the lingual surface. Because these are rigid they can be stressed and weakened by going into undercuts, so he creates guiding planes to eliminate undercuts in all the areas, except where the terminal (flexible) 1/3rd of the retentive clasp sits as he wants this to have an undercut to flex into (and sit under the survey line). Notice for final bit of the video the bur stops before the mesial half of the buccal surface (the surface facing away from the camera) - this is where the terminal third of the clasp would be
4.53 : We have lowered the height of contour.I thought it remains the same for abutment and we prepare guiding planes only.what are the indications for lowering the height of contour?
For a detailed explanation please read the section on "Surveying, Path of Insertion, Guiding Planes' in my RPD manual at removpros.dentistry.dal.ca/Manuals.html
For a detailed explanation please read the section on "Surveying, Path of Insertion, Guiding Planes' in my RPD manual at removpros.dentistry.dal.ca/Manuals.html Also view the video 'Prepare Retentive Undercut'
