The shear bond strength of artificial teeth with denture bases

الملخص EN

Background : Fracture and deboning of artificial teeth from denture bases are common clinical problems which are facing both the patient and the dentist.

The optimal combination of artificial teeth with visible light cured (VLC) denture base resin and the effect of thermocycling should be evaluated.

This study was conducted to evaluate and compare the shear bond strength of artificial teeth (acrylic and porcelain) with denture bases cured by water bath and visible light under the effect of different surface treatments and the effect of thermocycling with artificial saliva.

Material and methods : Heat polymerized (Densply) and visible light polymerized (Elite) acrylic resins were used.

Two types of artificial teeth (acrylic, Florident) and (porcelain, Ivoclar vivadent) were prepared.

Five specimens of each tooth type were processed to each of the denture base materials after the application of different surface treatments according to the manufacturer’s instructions.

Five specimens for each type of artificial teeth without surface treatments were also fabricated.

Specimens were thermocycled and tested for strength until fracture with an Instron universal testing machine.

Data were analyzed with analysis of variance and student T-test.

A photomicrographic microscope was used to identify adhesive and cohesive failures within debonded specimens.

Results : The mean force required to fracture the specimens were obviously larger for heat cured specimens compared with the light cured specimens.

The most common failure was cohesive within the tooth or the denture base.

With each base material, the artificial teeth which were treated with combined mechanical and chemical surface treatment exhibited the highest shear bond strength.

Thermocyclig had deleterious effect on the light cured specimens.

In general, heat polymerized groups failed cohesively within the artificial tooth.

While the light cured groups failed adhesively at the tooth denture base interface.

Conclusions : Within the limitations of this study, the type of denture base materials and surface treatments of the denture tooth selected for use may influence the shear bond strength of the tooth to the base.

Selection of more compatible combinations of base and artificial teeth may reduce the number of prosthesis fractures and resultant repairs.