“Comparative Evaluation of the Shear Bond Strength and Tensile bond strength of Hard and Soft tissue Denture Relining Materials Bonded to Microwave Cured Denture Base Resin and Conventional Heat Cured Denture Base Resin”

Abstract

Background:  Denture bearing tissues are subjected to different types and different magnitude of forces, they also undergo remodeling over a period of time. Hence, many a times the intaglio surface of the overlying prosthesis has to be relined to fit onto the modelled tissues. Denture Liners have been widely used in Prosthodontics to refit the tissue contacting surface of prostheses.   Chairside Denture (Hard and Soft) reliners are commonly used for this purpose they also act as shock absorbers i.e, help to distribute forces applied to soft tissues during function. It is very important that these lines bond to the denture surface to serve the purpose they are meant to. Various studies have been conducted to evaluate the bond strength of reline materials with conventional heat cure denture base resins however not much is known about the bonding of commercial denture reliners with other acrylics like microwave cured, light cured denture base resins. The present study was conducted to  evaluate and compare the Tensile and Shear Bond Strength of Hard and Soft Denture Relining Materials Bonded to Conventional Heat Cured Denture Base Resin versus Microwave Cured Denture Base Resin.

Materials & Methods: A total of 160 Cylindrical Specimens were made from Cylindrical Metal Mould of dimension 20mm length and 8mm diameter. 80 specimens each using Conventional Heat Cured Acrylic Denture Base Material and Microwave Cured Denture Base Material. The study was divided in to 8 groups. Each group contained 20 samples. The centre of cylinder was marked using a marker and 4mm was cut off from the midsection using water cooling Disc. The test samples (Heat cured & Microwave cured denture base resin) were placed back in the respective portion of the cylindrical mould. Repacking was done with reline resins .Tensile and shear bond strength test was done with  Instron Universal Testing Machine .Kruskal-wallis test was used for comparison of multiple groups followed by Mann-whitney U test that used for comparison the assessment of any significant differences between the groups.

Results: The highest mean Tensile bond strength value was obtained for Microwave cured denture base resin relined with G C Reline Hard (Kooliner) (27.08 MPa) and lowest for Heat cured denture base resin with G C soft denture reliner (1.04MPa). The highest mean Shear bond strength value was obtained for Microwave cured denture base resin relined with G C Reline Hard (Kooliner) (27.24 MPa) and lowest for Heat cured denture base resin with G C soft denture reliner (1.43MPa).

Conclusion: The microwave resin samples relined with hard liners exhibited maximum adhesion and showed highest tensile and shear bond strength value followed by heat cure resin samples relined with hard liners, microwave resin samples relined with soft liners and lastly heat cure resin samples relined with soft liners.