The effect of different packing methods, silinated glass fiber incorporation and Co-Cr framework involvement on the fit of acrylic denture base at the posterior palatal region

الملخص EN

Background : presence of teeth and deep palatal shape decrease the fit of acrylic resin denture to the master cast especially at the posterior region as well as the conventional packing system involves removal of the flasks from the press to the clamp that create pressure discontinuity may also aggravate the unfit of denture base.

The purpose of this study is to investigate the effect of tension packing system, incorporation of silinated short glass fiber, and Co-Cr framework involvement on the fit of acrylic resin denture base at the posterior palatal region of deep palate model in presence of teeth.

Material and Method : A silicon mold was used to prepare a (60) type VІ stone master cast, (30)casts were used in conventional packing system and the other half for tension packing system ,where each main group were subdivided into three sub groups (control , silinated short glass fiber, and Co-Cr framework involved groups) each consist of( 10) samples.

Acrylic dough was prepared and packed, in tension packing system the flasks were placed between the metal plates of tension device and the screws nuts were tightened before the final definitive closure, short curing cycle was undertaken.

Short glass fiber group’s samples were prepared using the same conventional denture base construction steps except for the addition of salivated short glass fiber(4mm) in (2 %) concentration.

Co- Cr framework was fabricated to occupy2/3 of palate, then acrylic resin –metal combination denture base were constructed.

Samples were cut anterior to the posterior palatal seal area.

The gap space between the acrylic base and the master cast was measured by travelling microscope.

Results : the results showed different fit of acrylic denture base to the cast at the different points in each sample where the ridge crests and the marginal borders points showed good fit in contrast to the mid palatal points that revealed the poorest fit in all the tested groups.

The Co-Cr groups showed the highest fit, followed by glass fiber groups while, the poorest fit were in the control groups.

Conclusion : it is concluded that Co-Cr framework involvement, incorporation of salivated glass fiber, and / or tension packing system had increased the fit in different grades.