A comparative in-vitro analysis of peel bond strengths of chair side resilient reline materials to conventional, additive, and subtractive manufactured denture bases.

Abstract

Purpose: To analyze peel bond strengths between three different denture bases and different classes of resilient reline materials. Methods: Denture base acrylic samples were fabricated using heat cured PMMA (ProBase Hot); according to manufacturer’s instructions in a custom fabricated stainless-steel mould to create rectangular acrylic blocks of 65 X10 X 3mm. Subtractive CAD/ CAM denture base samples were created using a band saw by sectioning prepolymerized PMMA pucks (IvoBase CAD) in test sample dimensions. For additive CAD/CAM denture base samples, first a prototype sample was designed using a free CAD software program (Meshmixer) and then 3D printed with a Form 3B printer, using a photopolymerizable denture base resin (Denture base RP). Post processing of 3D printed samples was carried out as per manufacturer’s recommendations. Test surfaces were prepared following a standardised protocol of polishing and washing. These samples were then relined with silicone-based liner (Tokuyama Sofreliner Tough S), a plasticized acrylic liner (Coe Soft); and for the second part of the study with a tissue conditioner (Coe Comfort). It was ensured that bonding was limited to only 22 mm of prepared test surface while remaining 43 mm of sample surface was left unbonded to allow peeling during testing. Samples were loaded into a Landmark® Servohydraulic testing machine and then peeled at crosshead speeds of 20 mm/min for resilient liners and 50 mm/min for tissue conditioner, until failure occurred. Results: In first part of study, results show, that type of denture base (p= 0.5274) and the 10-day water storage (p= 0.58073) had no significant effect on the peel bond strength values. Type of resilient liner did significantly affect the peel bond strength. Sofreliner Tough S (Mean1.6 ± 0.17MPa) had significantly higher bond strengths than Coe Soft (Mean 0.2 ± 0.10 MPa). In second part of study, results show, that type of denture base (P value = 0.00728) and the 10-day water storage (P value = 0.00278); had significant effect on the peel bond strength values of Coe Comfort. At 0-days, Coe Comfort showed highest mean peel bond strength with Probase Hot (Mean 0.28244 ± 0.20387 MPa). At 10-days of water immersion, Coe Comfort showed highest peel bond strength with Formlabs Denture Base RP (Mean 0.05599 ± 0.02177 MPa). There may be a generalized trend for peel bond strength reduction in both resilient liners and tissue conditioner with 10-day water immersion. Conclusion: Tokuyama Sofreliner Tough S has much higher peel bond strength as compared to Coe-Soft resilient liner. Peel bond strength of Coe Comfort is significantly affected by type of denture base and water immersion.