OBJECTIVES:
To evaluate the initial bonding properties of recently and previously introduced soft relining materials to denture base polymers with different polymerization techniques and different water content.

METHODS:
The initial tensile bond strength of 10 soft liners (Mollosil Plus, Dentusil, Ufi gel Soft, GC Reline Soft, Silagum Comfort, Vertex Soft, Astron Soft, Molloplast B, Flexacryl Soft, Triad Resiline) to three denture base polymers (Paladon 65, Palapress Vario, Ivocap Plus) were assessed with a modified method. Paladon 65 specimens immersed in water for 3 months were also used to test the effect of water content of denture base polymer on bond strength results. After testing, a visual examination of the fracture surfaces and a SEM investigation of the interface structure were performed. Tensile strength of each soft liner material was also tested. Data were analyzed statistically by two-way ANOVA (alpha = 0.05).

RESULTS:
Significant differences were found among tensile bond strength results (P < 0.05). Vinyl poly(organosiloxane) soft liners (Mollosil Plus, Dentusil, Ufi gel Soft, GC Reline Soft, Silagum Comfort) and a plasticized PMMA soft liner (Vertex Soft) gave statistically similar bond strength results for different denture base polymers (P>0.05). For the other materials used (Astron Soft, Molloplast B, Flexacryl Soft, Triad Resiline), different denture base polymers caused significantly different results (P < 0.05). Poly(organosiloxane) based materials gave slightly higher bond strength results with water immersed specimens than with the dry specimens.

SIGNIFICANCE:
A wide variety of newly formulated soft liners used in this study gave comparable or better bond strength results compared to Molloplast B.