Influence of chemical surface treatment on bond strength of acrylic teeth to conventional and nano-silica reinforced denture base resin: An in vitro study

Background: Debonding of acrylic denture teeth from denture base resin remains a frequent cause of prosthesis failure. Chemical surface modification of the ridge lap area and reinforcement of polymethyl methacrylate (PMMA) with nano silica particles have been proposed to enhance tooth-resin adhesion.

Aim: To evaluate and compare the effect of chemical surface modification using dichloromethane, ethyl acetate, cyanoacrylate and acetone on the shear bond strength of acrylic denture teeth bonded to unreinforced PMMA and nano silica (nSiO₂) reinforced PMMA denture base resin.

Materials and Methods: 50 standardized samples were fabricated and divided into two main groups based on denture base resin: conventional PMMA and nSiO₂ reinforced PMMA (2 wt%). Each group was further subdivided into five subgroups according to ridge lap surface treatment: control (no treatment), dichloromethane, ethyl acetate, cyanoacrylate and acetone. Heat-cure PMMA was processed using a conventional compression molding technique. All samples were stored in water for 7 days before testing. Shear bond strength was evaluated using a universal testing machine at a crosshead speed of 1 mm/min. Data were analysed using One-way ANOVA and post hoc tests (p ≤ 0.05).

Results: Chemical surface treatment significantly influenced bond strength in both resin groups (p < 0.001). Dichloromethane showed the highest bond strength for conventional PMMA (29.26 ± 0.63 MPa) and nSiO₂ reinforced PMMA (31.88 ± 0.59 MPa). Cyanoacrylate demonstrated the lowest values in both groups. Nano‑silica reinforced PMMA exhibited consistently higher bond strength than unreinforced PMMA across all surface treatments.

Conclusion: Chemical surface modification enhances the bond strength of acrylic denture teeth to denture base resin with dichloromethane being the most effective agent. Nano‑silica reinforcement further improves tooth-resin adhesion. The combination of dichloromethane surface treatment and nSiO₂ reinforced PMMA provides the highest bond strength and may improve the clinical longevity of complete dentures.