RPD qestion

[NYtimes]

Hey Guys;
I have a question regarding RPD design. in class 2, on tooth supported side, first premolar and first molar are missing. in the book, there are two rests on M and D side of second premolar. and a WW on B side. I was wondering what happend to reciprocal arm??
and another question is that can we remove mesial rest and put a reciprocal arm with circum clasp on second premolar?
what if we remove WW and put a retentive arm and reciprocal arm on canine?

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[tinman831]

We could better answer your question if we knew what it was. Feel free to ask. 🙂

 

[dentheartthrob]

I've always thought that wrought wires were just used for interim prosthesis. Concerning the canine, I would assume that it would be contraindicated due to esthetic reasons

 

[charlestweed]

I don’t think you can remove mesial rest and put circumferential clasp on the second premolar because this would flex and damage that tooth when the patient chews on the partial denture. Mesial rest is a very important fulcrum that allows the partial to swing up and down (during mastication) without putting too much stress on the 2nd premolar. At our school, we are taught to put M + D rests (or just a mesial rest) on occlusal fossa and an “I bar” on the buccal of 2nd premolar for this particular case. For reciprocity, I would put a reciprocal I bar on the contralateral 2nd premolar. My 2 cents.

I agree w/ Denthearthrob. You should not put a clasp on the canine….patient would not be very happy.

 

[ivorinedust]

A canine or a premolar may be "esthetically" clasped using an RPI--rest, plate and I bar ( " a rest on M and D sides and WW on the bucccal side" as the OP may have erroneously described), with the I bar approaching the infrabulge from the cervical and engaging the undercut just below it. For most people who have normal smile lines the clasp would be barely noticeable as it would be fully or partially hidden by the lips.

If using an RPI on a distal extension or tooth supported denture, a reciprocating arm may be placed on the lingual of the abutment tooth, originating from the mesial rest, but for hygienic reasons, this arm may be omitted if a distal plate is placed on the tooth as part of the RPI assembly. It goes without saying that the mesial rest must remain as a component of the RPI. Properly executed, a distal plate will 'reciprocate' effectively. So you don't have to wonder why there was no reciprocal arm. It was not needed.

In the case of the missing first premolar and 1st molar teeth, the abutment 2nd premolar need not be clasped, but may be utilized as a pier abutment. Mesial and distal plates (and rests) are employed on the sides of the tooth adjacent to the edentolous areas.

Ivorinedust

"Apolonia, relieve my toothache!"

 

[ICrownUrTeeth]

I've always thought that wrought wires were just used for interim prosthesis. Concerning the canine, I would assume that it would be contraindicated due to esthetic reasons

WW are great clasps to use. It is has the ability to flex in all directions, hence less torque to the teeth. WW use in conjunction with a cast reciprocal element is called a combination clasp.

In a lot of RPD cases, abutment teeth has buccal undercut that does not allow RPI design. If esthetics is an issue, for kenedy class IV cases, use rotational path design.

 

[NYtimes]

A canine or a premolar may be "esthetically" clasped using an RPI--rest, plate and I bar ( " a rest on M and D sides and WW on the bucccal side" as the OP may have erroneously described), with the I bar approaching the infrabulge from the cervical and engaging the undercut just below it. For most people who have normal smile lines the clasp would be barely noticeable as it would be fully or partially hidden by the lips.

If using an RPI on a distal extension or tooth supported denture, a reciprocating arm may be placed on the lingual of the abutment tooth, originating from the mesial rest, but for hygienic reasons, this arm may be omitted if a distal plate is placed on the tooth as part of the RPI assembly. It goes without saying that the mesial rest must remain as a component of the RPI. Properly executed, a distal plate will 'reciprocate' effectively. So you don't have to wonder why there was no reciprocal arm. It was not needed.

In the case of the missing first premolar and 1st molar teeth, the abutment 2nd premolar need not be clasped, but may be utilized as a pier abutment. Mesial and distal plates (and rests) are employed on the sides of the tooth adjacent to the edentolous areas.

Ivorinedust

"Apolonia, relieve my toothache!"

Thanks for your complete answer. second paragraph regerding the omitted reciprocal arm was not convincing. when the WW is in action, it forces the tooth toward the Lingual. does the guiding plate prevent this force? guiding plate does not cover the tooth in the lingual side. I was thinking that it can just prevent torque toward M or D.