6CHAPTER 6DENTURE BASESDEFINITIONA denture base is that part of adent - PDF document

6-CHAPTER 6DENTURE BASESDEFINITIONA denture base is that part of adenture which rests on the foundation areasand to which teeth are attached.1The functions of denture bases areto:Attach the prosthetic teeth tothe RPD.2.sfer occlusal forces tothe abutment teeth and, intooth-tissue supported RPDs,to the denture foundationarea.Replace the missing alveolartissue in bulk andappearance.To provide bracing, retention,and in tooth-tissue supportedRPDs direct- indirectretention.DESIRABLE CHARACTERISTICSClassic lists of requisites for the"ideal" denture base appear in McCracken's2and Applegate's3 textbooks. Theserequirements reworded, expanded andslightly modified are: 1.Be dimensional stable duringfabrication, use, repair andreline/rebase.Be chemically inert or at lestcompatible with the oraltissues.Not have a taste or odor andshould not pick up a taste orodor from oral fluids. 4.Have a surface which isdense to avoid harboring oforal fluids andmicroorganisms.Be capable of adaptingaccurately to the master cast. 6.Be capable of being adjusted,finished and polished withinstruments available in thedental office. 7.Be abrasion resistant. 8.Be capable of being cleanedby usual oral hygienetechniques and materials. 9.Be of low initial cost andinexpensively repaired andrelined/rebased.Be capable of being repairedand relined/rebased bycustomary dental techniques.11.Be a good thermal conductor.12.ve a low specific gravityfor maxillary RPDs and aspecific gravity similar, to orslightly greater than, thetis

sues it is replacing formandibular RPDs.13.Have resilience and impactstrength sufficient to permitthe use of a thin base.14.y bond toprosthetic tooth materials andRPD alloys.15.Be strong enough to resist thestresses which will be appliedto it.16.Be capable of being coloredto match the various mucosacolors and retain this colorwith time, use, and cleansing.17.Not soften or warp in hotwater or other cleansingsolutions.There is no denture base materialwhich meets all of these requirements.However, the currently used denture base 6-materials (metal and plastic) are verysatisfactory.There are two types of RPD denturebases: (1) metal, and (2) plastic.THE METAL DENTURE BASEThe metal denture base (Fig. 6-1) hasmetal in contact with the edentulous ridge.Prosthetic teeth are attached to the metalbase with a plastic base or by cementation toa retentive post. Fig. 6-1.  A metal denture baseINDICATIONS:A tooth supported edentulousspace where further boneresorption is not anticipated.2.When a facing, tube tooth,metal pontic, or metalreinforced denture tooth is tobe used.3.A tooth-tissue supportededentulous space when the"floating denture base"concept is being used.CONTRAINDICATIONS:Tooth-tissue supportededentulous space.2. Tooth supported edentulousspace where bone resorptionis expected.ADVANTAGES:Very rigid.2.High thermal conductivity.Thermal conductivity may bedecreased if plastic isprocessed onto the metalbase.Very stable form.4.High abrasion resistance.5.Less porous than plastic andthere

fore easier to clean.DISADVAMore difficult to adjust tissuesurface than a plastic base.2.More difficult to reline themetal tissue surface.3.Metal not esthetic.THE PLASTIC DENTURE BASEThe plastic denture base (Fig. 6-2)has plastic in contact with the edentulousridge. It is used more frequently than themetal base. Fig. 6-2.  A plastic denture base Metal Metal DentureBase RetentionMinor 6-Tooth-tissue supportededentulous spaces.2.Tooth supported edentulousspaces where bone resorptionwill necessitate areline/rebase.Where considerable missingalveolar tissue must bereplaced.here esthetics is a primaryconcern.Single tooth edentulousspaces.Where protrusive or lateralocclusal guidance will be onthe prosthetic teeth.ADVANTAGES:Can be easily relined.2.Easy to fabricate, adjust,finish and polish, and repair.3.Plastic is more esthetic thanmetal.More porous than metal andtherefore more difficult toclean.Requires more bulk forrigidity than metal.3.Easily abraded.4.Easily fractured.5. is a poor thermalconductor.Has the potential to bedimensionally unstable.Note: The high impact plasticdenture base materials suchas Lucitone 199 haveimproved resistance toabrasion and fracture.REFERENCESThe glossary of prosthetic terms. 6thed. St. Louis, C V Mosby, 1994.2.Henderson D, McGivney G P,Castleberry D J. McCracken'sremovable partial prosthodontics.7th ed. St. Louis, C V Mosby1985:131.Applegate O C. Essentials ofremovable partial denture prosthesis.2nd ed. Philadelphia, W BSaunders, 1960:14