In Vitro Shear Bond Strength of Additively Manufactured Denture Base Resins to Hard Chairside Reline Materials.

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Additive Manufacturing in Dentistry

Background:

• Reliable bonding between denture base resins and chairside reline materials is critical for denture longevity.
• Limited evidence exists on the bond strength of additively manufactured denture bases with reline materials under simulated aging.

Purpose of the Study:

• To evaluate the shear bond strength (SBS) of two hard chairside reline materials to conventional PMMA and two additively manufactured denture base resins.
• To assess the influence of thermocycling, simulating clinical aging, on the bond strength and failure modes.

Main Methods:

• Six material combinations were tested: two additively manufactured resins (UDMA, MA) and one conventional PMMA bonded with two reline materials (R, U).
• Specimens underwent three conditions: non-thermocycling (NT), thermocycling before relining (TB), and thermocycling after relining (TA).
• Shear bond strength was measured, and failure modes were analyzed after thermocycling.

Main Results:

• Denture base resin type, reline material, and thermocycling significantly affected SBS (P < .05).
• The U reline material consistently showed higher SBS than R across all denture bases.
• After thermocycling, the U groups exhibited no failures, while R groups showed significant debonding (20-80%) and predominantly adhesive failures.

Conclusions:

• Material compatibility and thermal aging critically influence bonding performance between denture bases and reline materials.
• The U reline material demonstrated superior resistance to thermally induced debonding compared to R.
• Proper selection of hard chairside reline materials can achieve bonding performance comparable to conventional PMMA for additively manufactured dentures.