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Clinical Protocol for Removable Partial Dentures. Diagnosis & Treatment Planning. Gather diagnostic info Make preliminary impressions Pour diagnostic casts. Mounting Diagnostic Casts. If required: Extruded teeth Severe attrition Insufficient interarch space Deep overbite, etc.
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Diagnosis & Treatment Planning • Gather diagnostic info • Make preliminary impressions • Pour diagnostic casts
Mounting Diagnostic Casts • If required: • Extruded teeth • Severe attrition • Insufficient interarch space • Deep overbite, etc. • use Semiadjustable Articulator
Formulate Treatment Plan • Overall Treatment Plan • Specific RPD Treatment Plan • Select abutments, direct retainers • Major connectors • Position of rests, g.p., bracing & retentive arms
Critical!!! • When RPD is part of treatment: • Draw design on surveyed cast • Design approved before any treatment started: • Affects direct restorations • Can influence need for/preparations for crowns • Insures RPD can be completed successfully • Survey, tripod, heights of contour
Formulate Treatment Plan • Discuss with instructor prior to discussing with patient • Provide rationale for design
Final Impressions for Partial Dentures • Framework Impression • Altered Cast Impression
Framework Impression Border Molded Custom Tray • Tray that is made for patient • Mold tray periphery with thermoplastic compound
Framework Impression • Material of Choice • Polyvinyl Siloxane
Framework Impression • Polyvinyl siloxanes • Excellent dimensional stability • Good tear strength • No taste • Glove contamination • Relatively hydrophobic - improved
Prior to the Final Impression • No plaque or calculus • Healthy soft tissues • Initial therapy complete
Prior to the Final Impression • Make alginate impression to check: • Guiding planes • Rest seats • Retentive areas • Heights of contour
Framework Impression • Syringe low viscosity material • Around abutment teeth • Over occlusal surfaces • Use care in rest seats • Do not over fill trays - overextension
Framework Impression • Medium viscosity in tray • Increased filler content • less shrinkage • Less displacement of soft tissues than high viscosities
Evaluating the Impression • Absence of Significant Voids • Any area where metal contacts abutment (e.g. rests, minor connectors) • Any area where major or minor connectors contact soft tissue
Evaluating the Impression • Peripheries well defined • Accurately records supporting tissues • Allows for all elements of design
Evaluating the Impression • Mandible • Measure FGM to floor of mouth • Record measurements • Transfer to cast - inferior framework border
Evaluating the Impression • No significant areas of “burn through” • Border molding not covered • Displaces the tissue • Change in contour caused by the border molding
Evaluating the Impression • Impression integrity • No significant tears • Not separated from tray
Evaluating the Impression • Critical Anatomy Recorded • Vestibular depths • Hamular notches (marked) • Vibrating line (marked) • Retromolar pads • Frenal attachments • Floor of mouth (measured)
Preparation for Impression • Practice inserting & removing tray • Dry tissues
Preparation for Impression • Block out • large embrasures • bridge pontics • Don’t cover occluding or framework surfaces
Preparation for Impression • Teeth must be DRY for wax to stick
Don’t Reseat Impression • Won’t fully seat over undercuts
Framework Impression • Box & pour impression • Survey & tripodize • Draw design • Send to Lab with Work Authorization for framework fabrication
Master Cast • Pour in improved dental stone • Type IV (Silky Rock) • Vacuum mix stone • Allow to set at least 1 hour • strength to resist fracture
Master Casts • No significant bubbles or flaws • Teeth not fractured from cast • Includes all anatomical surfaces of final impressions • Includes 3-4 mm. land area
Master Cast • Base parallel ridge • 12 mm (.5”) thick (minimum) • Evidence of a dense stone surface • Clean & well trimmed (keep wet while trimming)
Pour Secondary Cast • Draw design on secondary cast • Checked/corrected with instructor • Correct design on 2nd cast • Send to lab with 1st poured cast • lab will transfer the design to this cast
RPD Protocol Summary • Diagnosis, Treatment Plan, Hygiene • Diagnostic Casts • Draw Design & list abutment modifications • Instructor Approval • Abutment modifications • Preliminary impression to check mod.’s • Final Framework Impression • Pour two casts
RPD Protocol Summary • Draw design on 2nd cast • Instructor approval/corrections • Cast to Lab with 1st pour & prescription • Inspect framework waxup • Framework Adjustment • Altered Cast impression, if needed • Try-in with teeth in wax • Process, deliver to patient