Improving reline bonding in 3D-printed dentures: an experimental in vitro study

Area of Science:

• Materials Science
• Biomaterials Engineering
• Dental Prosthetics

Background:

• 3D-printed denture bases offer customization but may require relining.
• Evaluating the bond strength of relined 3D-printed materials is crucial for durability.
• Polymethylmethacrylate (PMMA) is a common material for denture relining.

Purpose of the Study:

• To assess the tensile bond strength of 3D-printed denture bases relined with conventional PMMA resin.
• To compare the efficacy of various surface treatment protocols on bond strength.
• To determine if surface treatments can restore bond strength to levels comparable to intact specimens.

Main Methods:

• Ninety 3D-printed resin specimens were divided into nine groups with varying surface treatments (control, monomer application, sandblasting, combinations, and bonding agents).
• Tensile bond strength was evaluated using universal testing machines at a crosshead speed of 1 mm/min.
• Fracture patterns were analyzed microscopically, and data were statistically analyzed using Kruskal-Wallis ANOVA and Dunn's post hoc test.

Main Results:

• The intact control group exhibited the highest ultimate tensile strength (UTS) (25.9 MPa).
• Sandblasting combined with monomer application (19.7 MPa) yielded the highest UTS among treated groups, significantly higher than no treatment (11.5 MPa).
• All relined specimens showed adhesive failures at the interface, indicating bond strength limitations.

Conclusions:

• Surface treatments improve the bond strength of relined 3D-printed denture bases but do not fully restore it to original levels.
• Sandblasting combined with monomer application is a simple and effective surface treatment for enhancing bond strength.
• These findings suggest that accessible surface treatments may be preferable to complex bonding systems for relining 3D-printed dentures.