Presentation on theme: "Lab Techniques for Flexible Partial Dentures"— Presentation transcript:
1 Lab Techniques for Flexible Partial Dentures Valplast Presentation - Peterson Airforce Base
2 Introduction to Flexible Partials Simple solution to provide a removable restorationNo tooth preparation neededNo metal frame neededFinished partial with one trip through the laboratoryInjection TechniqueValplast Partials are repairable and relinableGuaranteed not to breakValplast Presentation - Peterson Airforce Base
3 Type of Material Valplast is a type of Nylon Thermoplastic Injection MoldedDenser than acrylicLower Water Absorption than PMMAFlexural modulus around 470MPa at body temperature (making it both flexible and sturdy)In use since 1953
4 Lab Procedure - Overview Design, block and relieve master modelDuplicate stone modelTry-in (if required) or Set-up on MasterTransfer set-up to duplicate modelWax with prefabricated patternsInvest, Sprue, Wax EliminationProcess with Manual InjectorFinish and Polish
33 Advising Clinician on Insertion and Adjustment Partial must be placed in very hot water (150°F or more) for a minute prior to insertion and allowed to cool to a tolerable temperature.This process makes the partial as flexible as it would be at body temperature. This minimizes adjustments
34 AdjustmentsMinor clasp tightening or loosening can be done by heating the clasp again in very hot water and bending it severely in the needed direction. This will purposely warp the area enough to change its positionGrinding should be done as a last resort.Use a Standard Green Mounted Stone (used usually for porcelain) to adjust Valplast. 20K to 30K rotation and constant motion
35 Small Additions - Welding Using hot air welder and welding rod, build up a boxing in the addition site to secure a new toothSelect a matching acrylic tooth.Break a porcelain tooth to obtain pinsHeat each of two pins in flame to cherry red and embed in the partial half way (pin head protruding)Cure scooped stock tooth over pins using tooth-shade or pink acrylic.
36 Large Additions – Injection Wax new section on duplicate model to original partialInvest, Sprue, Wash out waxPrepare bonding site with acid etch solution (Val-Fuse Repair Liquid)Inject, finish, and polish
37 Relines Take Putty Matrix to record tooth position Strip teeth from partial (in blocks) while duplicating the model.Rewax new base using matrix to position teethInvest and process using repair technique to bond top-half exposed Valplast to new base.Finish and Polish
38 Clinical Prep for Tooth Addition Clinician should take overall alginate impression to lift out caseCounter-model for biteBefore pouring the model, any deposits or adhesives should be removed from surface or the process will lead to an unintended reline.
39 Clinical Prep for Reline Closed-mouth rubber-base reline impression.Pick-up overall alginate impression.Counter not necessary