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Denture base

Dr.Shanai M.



Denture base: is that part of partial denture that supports artificial teeth and transfer occlusal forces to supporting oral structures
The primary function of denture base
• Masticatory function: as the d. base transfer the occlusal stresses to the underlying supporting oral structures.
• Esthetic or cosmetic function: this is related to reproduction of natural looking contours.
• Stimulation of the underlying tissue by massaging action during vertical movement of the denture base under functional stress, as this will maintain the form and health of underlying tissue
Types of denture base according to support:
• Tooth supported partial denture
• Tooth tissue borne partal denture.

Tooth-Supported Partial Denture Base

In a tooth supported prosthesis, the denture base is primarily a span between two abutments supporting artificial teeth. Thus occlusal forces are transferred directly to the abutments through rests. Also, the denture base and the supplied teeth serve to prevent horizontal migration of all abutment teeth in the partially edentulous arch and vertical migration of teeth in the opposing arch.
When only posterior teeth are being replaced, esthetics is usually only a secondary consideration. On the other hand, when anterior teeth are replaced, esthetics may be of primary importance. Theoretically, the tooth-supported partial denture base that replaces anterior teeth must perform the following functions: (1) provide desirable esthetics; (2) support and retain the artificial teeth in such a way that they provide masticatory efficiency and assist in transferring occlusal forces directly to abutment teeth through rests; (3) prevent vertical and horizontal migration of remaining natural teeth; (4) eliminate undesirable food traps (oral cleanliness); and (5) stimulate the underlying tissues.

Tooth tissue born partial denture base

In a distal extension partial denture, denture bases other than those in tooth-supported modifications must contribute to the support of the denture.
The edentulous area close to the terminal abutments is supported primarily by the occlusal rest on the abutment teeth however; farther from the abutment the support from the underlying ridge tissue becomes increasingly important
Maximum support from the residual ridge may be obtained by
1.using broad denture base
2. accurate denture bases
Both spread the occlusal load justifiably over the entire area available for such support. This maximum support can be obtained through good impression of the distal extension ridge,

• also the distal extension base required relining and rebasing in the future,

So the material being used for tooth tissue supported partial denture should allow relining and rebasing which is not necessary in tooth porn partial denture as its supported at each end on a tooth through the rest, while the condition where relining is required where gross tissue changes (bone resorption) have been occurred beneath tooth tissue base to the point that poor esthetic and food accumulation result.
Types of denture base
• Resin type (acrylic denture base)
• Metal type denture base.

Resin type denture base

Its most widely used type of D.B. because of easy of fabrication and easy of attachment to metal framework. the resin D.B. attached to metal framework by mechanical mean (through out the hole present in meshes or ladder area) in addition, the resin D.B. having the advantage of future relining or rebasing therefore its of main choice in:
• Distal extension ridges: the resin D.B. is indicated for distal extension cases (CL.I&CL.II) because of the support of the denture by tissue and there will be continuous bone resorption creating a space between residual ridge and D.B. so there will be need for relining.
• long span ridge: in CLIII&CLIV edentulous cases because of possibility of tissue changes underneath the B.D. and there will be need for future relining.
• In case of immediate partial denture: since after healing period there will be need for relining so that resin D.B. will be needed for such cases.


Metal type D.B.
Its made of either
• Gold and platinum but this material are so expensive.
• Stainless steel or cr-co, which is more being in use now day.
• Recently, the titanium being used as denture base and in oral implant because of its excellent properties.
The metal type D.B. has the ability to stimulate the underlying tissues that will maintain the integrity of the bone by preventing osseuse tissue resorption, but its principle disadvantage is difficulty to reline in future, therefore the metal type D.B. will be indicated in:
• Short span (tooth born removable p.d)
• When there is no enough space for artificial teeth (in adequate intermaxillary space) because of over eruption of apposing teeth.

Advantage of metal denture bases

• Accuracy and permanency of form: the metal alloys take accurate form and don’t permit changes by internal factors (internal stains that may be released later and cause distortion are not present). Because accuracy, the metal base provides an intimacy of contact that contributes considerably to the retention of a denture prosthesis. Permanence of form of the cast base is also ensured because of its resistance to abrasion from denture cleaning agents.
• Comparative tissue response: clinical observation have demonstrated that the inherent cleanliness of cast metal base contributes to maintain the health of oral tissues when compared with acrylic resin base, this may be due to greater density and bacteriostatic activity contributed by ionization and oxidation of metal base, while acrylic resin tend to accumulates mucineous deposits, bacteria may accumulate and producing a harmful enzymes to underlying tissues.

• Thermal coductivity: temperature changes are transmitted through the metal base to the underlying tissues, there by helping to maintain the health of these tissues, while acrylic D.B. have an insulting properties that prevents interchange of temperature between D.B. and underlying tissues; therefore the metal D.B. give more natural feeling from resin D.B.
• Weight and bulk : metal alloys may be casted much thinner than acrylic resin and still have adequate strength and rigidity: therefore the metal D.B. will be less weight and bulk than the resin D.B.
Disadvantages of metal D.B.
• Difficult to reline and rebase.
• Expensive
• The error that occur in posterior palatal seal area (post dam) cant be corrected with metal D.B., while if same error occurred in resin D.B. repostdaming is the choice for this problem.

Design consideration of D.B.

• Support: maximum support from D.B. depending on limiting anatomical structures and their movement during function and accuracy od denture base
• Esthetic and stimulation underlying tissues
• Whether we have a free end extension or bounded saddle edentulous cases.
• Type of metal alloy being used in fabrication of D.B.
• Thickness required of D.B.


Periodontal consideration of D.B. design
• D.B. should be of optimal extension and thickness to reduce stresses on abutment
• D.B. should not impinge on gingival tissues.
• D.B. should expose the gingival tissues (relief in area that not involve in periodontal disease)
Types of artificial teeth
• Acrylic teeth: artificial teeth that have been made of acrylic resin, it has the ability to be attached chemically to D.B.
• Porecelain teeth: its attached to D.b. by mechanical mean, either by pin that will be processed in D.B. and a hole is presenting the base of the tooth allowing its attachment by cementation.
• Metal teeth: some cases the molar teeth may be processed as part of the D.B. by casting procedture this is indicated in cases od limited intermaxillary spaces