In Vitro Tensile Strength Comparison of Denture Liners to 3-D Printed Denture Resin

Objectives: In vitro study to compare tensile bond strength of 2 soft tissue liners, A-Lynol®(Dentsply Caulk) and B-CoeSoft®(GCAmerica) to TrueDent Polyjet®(Stratasys) printed denture material modified with 3 types of surface pre-treatment.
Methods: 60 pairs of TrueDent®(10x10x20mm) resin blocks with 10x10mm interfacing surfaces were fabricated using J5 DentaJet Polyjet® print cycle 5h9m. Blocks processed to manufacturer’s specification, pressure washed, soaked in 2%NaOH solution(120m), pressure washed-second cycle, post-cured in glycerin 80°C,60mx2cycles with agitation of liquid between cycles. Blocks soaked in 70% isopropyl alcohol(30m), air dried(2hrs) ,divided into 3 surface pretreatment groups per material(n=10). Group1-acrylic bur HPSGEB,Brassler®, Group 2-air abrasion 50µ AlO,15s,65psi,4.5bar; Group 3-medium grit slurry/ragwheel(30s) as control. Surface treatment confirmed using 3.5X magnification. Opposing blocks positioned 3mm apart using PVS matrix. Reline materials placed on opposing resin surfaces, cured(24h), placed in distilled water(24h). Instron1123/44R universal testing instrument with 5mm/min crosshead speed using 500N(50kg) load cell measured max load and tensile strength. Results analyzed with 2-way ANOVA/Tukey(p<0.05)
Results: See Table I. Adhesion of liner A to printed resin was significantly stronger than B with surface treatments pooled(p<0.001). Bur pretreatment of printed resin produced strongest adhesion with liner A, compared to any other liner/surface treatment combination(p<0.05). No significant differences observed among remaining liner/treatment combinations(p≥0.05) except for pumice/B, which was significantly lower than all liner A treatments(p<0.05).
Conclusions: Best adhesion to TrueDent® printed resin was obtained withacrylic bur pretreatment and use of Lynol® liner.