Microtensile bond strength of different acrylic teeth to high-impact denture base resins.

PURPOSE: This study evaluated the effect of denture base acrylic, denture tooth composition, and ridge-lap surface treatment on the microtensile bond strength (µTBS) of three commercially available denture teeth and two injection denture processing systems. MATERIALS AND METHODS: Sixteen experimental groups were formed (n = 3), according to denture tooth surface treatment (no treatment or surface treatment recommended by the manufacturer), denture base processing technique and acrylic (SR-Ivocap-Ivocap Plus or Success-Lucitone 199), and tooth type-composition at bonding interface (BlueLine DCL-PMMA, Portrait IPN-PMMA, Phonares II-PMMA, Phonares II-NHC). Rectangular bar specimens with a 1 mm(2) cross sectional area were fabricated and subsequently thermocycled at 10,000 cycles between 5°C and 55°C with a 15-second dwell time. Select specimens underwent µTBS testing in a universal testing machine with a 1 kN load cell at 0.5 mm/min crosshead speed. Data were analyzed statistically by two and three-way ANOVA and Tukey post hoc test (α = 0.05). RESULTS: Mean µTBS ranged between 56.2 ± 5.6 and 60.8 ± 5.0 N/mm(2) for the Ivocap Plus specimens and 13.3 ± 5.12 to 60.1 ± 6.0 N/mm(2) for the Lucitone 199 specimens. Among the Ivocap specimens, BlueLine DCL and Phonares II NHC had significantly higher µTBS than Portrait IPN to Ivocap Plus acrylic. There were no statistically significant differences among Blueline, Phonares II PMMA, and Phonares II NHC, or between Phonares II PMMA and Portrait IPN. Within the Luctione 199 specimens, there was a significantly higher µTBS for BlueLine DCL and Phonares II NHC denture teeth with the manufacturer-recommended surface treatment when compared to control surface. BlueLine, Portrait, and Phonares II PMMA groups achieved significantly higher mean µTBS than the Phonares II NHC group. There were no statistically significant differences among BlueLine, Portrait, and Phonares II PMMA groups. CONCLUSION: When evaluating the µTBS of PMMA and NHC denture teeth to base resins, a stronger bond was achieved using materials produced by the same manufacturer. Within the Luctione 199 specimens, the Phonares II NHC group demonstrated significantly lower bond strength than other specimens, suggesting that gross ridge-lap reduction of NHC denture teeth is not recommended if a base acrylic by a different manufacturer from the tooth is going to be used.

Sensitivity of Candida albicans biofilm cells grown on denture acrylic to antifungal proteins and chlorhexidine.

OBJECTIVES: Candida albicans cells form biofilms on polymeric surfaces of dentures and other prostheses introduced into the oral cavity. Many biofilm microorganisms exhibit resistance to antimicrobial agents; C. albicans cells may also develop resistance to naturally occurring antifungal peptides in human saliva including histatins (Hsts) and defensins (hBDs). Therefore, we evaluated Hst 5 activity on C. albicans biofilm cells compared to planktonic cells and measured whether surface treatment of denture acrylic with Hst 5, hBD-3, or chlorhexidine gluconate could inhibit in vitro biofilm development. METHODS: Acrylic disks were preconditioned with 500 microl saliva for 30 min, and inoculated with C. albicans cells (10(6)cells/ml) for 1h, at 37 degrees C. Non-adherent cells were removed by washing and disks and were incubated in YPD growth medium for 24, 48, and 72 h at 37 degrees C. Candidacidal assays were performed on 48-h-biofilms and on planktonically grown cells using Hst 5 (15.5, 31.25, and 62 microM). Cell adhesion was compared on disks pre-coated with 0.12% chlorhexidine gluconate, 50 microM Hst 5, or 0.6 microM hBD-3 after 24, 48, and 72 h growth. RESULTS: No significant difference was observed in sensitivity to Hst 5 of biofilm cells compared to planktonic cells (p>0.05). Pre-coating disks with hBD-3 did not inhibit biofilm development; however, Hst 5 significantly inhibited biofilm development at 72 h, while 0.12% chlorhexidine significantly inhibited biofilm development at all time intervals (p<0.05). CONCLUSIONS: C. albicans biofilm cells grown on denture acrylic are sensitive to killing by Hst 5. Surface coating acrylic with chlorhexidine or Hst 5 effectively inhibits biofilm growth and has potential therapeutic application.