STATEMENT OF PROBLEM: Bonding failures of repair resin to denture base resin occurs when denture base resin is wet, however, little is known of how water relates to failures. PURPOSE: This study evaluated the influence of water absorbed in denture base resin on the bond strength and resistance to cyclic thermal stresses of autopolymerizing resins bonded to denture base resin. MATERIAL AND METHODS: Denture base resin disks (n = 180; 12 mm diameter and 3 mm thick) were fabricated from heat-polymerized acrylic resin (Lucitone 199). The disks were divided into groups (n = 60) with 3 conditions of water content: (1) complete water saturation (control), (2) superficial desiccation by blowing air on the specimen, or (3) complete desiccation. Each denture base specimen received 1 of 3 surface treatments (n = 20) including: (1) no treatment, (2) airborne-particle abrasion, or (3) methylene chloride application. An autopolymerizing repair resin (Repair Material, n = 10) or reline resin (Tokuso Rebase Normal set, n = 10) was applied to the bonding area (5 mm diameter) and polymerized at 37 degrees C for 10 minutes. The resistance to cyclic thermal stress was determined after subjecting the specimens to 50,000 thermal cycles between 4 degrees C and 60 degrees C water baths with a 1-minute dwell time (n = 5 per group). Bond strength (MPa) was measured by shear bond testing at a 1.0 mm/min crosshead speed until the applied resin debonded from denture base resin. Data were statistically analyzed by 3-way analysis of variance and multiple comparisons among the groups were performed with Bonferroni test (alpha = .05). RESULTS: The mean bond strengths of repair resin to airborne-particle-abraded denture base specimens were not significantly influenced by either thermal cycling or water content. The mean bond strengths of reline resin significantly decreased after thermal cycling (P < .0001) regardless of the conditions of surface treatment and water content. For methylene chloride treated specimens, bond strengths of both repair and reline resins to completely water saturated specimens were significantly higher than those of completely desiccated specimens (P = .0048 for repair resin, P < .0001 for reline resin) after thermal cycling. CONCLUSIONS: Bond strengths of autopolymerizing resin to denture base resin were not significantly influenced by water content of denture base resin but were significantly influenced by resin type, thermal cycling, and surface treatment.
STATEMENT OF PROBLEM: Bonding failures of repair resin to denture base resin occurs when denture base resin is wet, however, little is known of how water relates to failures. PURPOSE: This study evaluated the influence of water absorbed in denture base resin on the bond strength and resistance to cyclic thermal stresses of autopolymerizing resins bonded to denture base resin. MATERIAL AND METHODS: Denture base resin disks (n = 180; 12 mm diameter and 3 mm thick) were fabricated from heat-polymerized acrylic resin (Lucitone 199). The disks were divided into groups (n = 60) with 3 conditions of water content: (1) complete water saturation (control), (2) superficial desiccation by blowing air on the specimen, or (3) complete desiccation. Each denture base specimen received 1 of 3 surface treatments (n = 20) including: (1) no treatment, (2) airborne-particle abrasion, or (3) methylene chloride application. An autopolymerizing repair resin (Repair Material, n = 10) or reline resin (Tokuso Rebase Normal set, n = 10) was applied to the bonding area (5 mm diameter) and polymerized at 37 degrees C for 10 minutes. The resistance to cyclic thermal stress was determined after subjecting the specimens to 50,000 thermal cycles between 4 degrees C and 60 degrees C water baths with a 1-minute dwell time (n = 5 per group). Bond strength (MPa) was measured by shear bond testing at a 1.0 mm/min crosshead speed until the applied resin debonded from denture base resin. Data were statistically analyzed by 3-way analysis of variance and multiple comparisons among the groups were performed with Bonferroni test (alpha = .05). RESULTS: The mean bond strengths of repair resin to airborne-particle-abraded denture base specimens were not significantly influenced by either thermal cycling or water content. The mean bond strengths of reline resin significantly decreased after thermal cycling (P < .0001) regardless of the conditions of surface treatment and water content. For methylene chloride treated specimens, bond strengths of both repair and reline resins to completely water saturated specimens were significantly higher than those of completely desiccated specimens (P = .0048 for repair resin, P < .0001 for reline resin) after thermal cycling. CONCLUSIONS: Bond strengths of autopolymerizing resin to denture base resin were not significantly influenced by water content of denture base resin but were significantly influenced by resin type, thermal cycling, and surface treatment.
Authors: Ana L Machado; Bruna C Bochio; Amanda F Wady; Janaina H Jorge; Sebastião V Canevarolo; Carlos E Vergani Journal: J Dent Biomech Date: 2012-09-12