Influence of chairside surface treatments on the shear bond strength of PEKK polymer to veneering resin materials: An in vitro study.

STATEMENT OF PROBLEM: High-performance thermoplastics have been adopted as an alternative restorative material to metal or ceramics. However, a straightforward surface modification process to provide a durable bond strength between the polymer and the veneering material is lacking. PURPOSE: The purpose of this in vitro study was to evaluate the shear bond strength (SBS) of different veneering resin materials to polyetherketoneketone (PEKK) after different surface treatments. MATERIAL AND METHODS: Rectangular (7×7×2 mm) PEKK specimens (N=120) were randomly allocated to the following 6 groups (n=20): untreated (Cnt); nonthermal plasma (NTP) treated; tribochemical silica airborne-particle abrasion with 30-µm silica-modified Al2O3 (Tbc); abraded with a coarse-grit diamond rotary instrument (Ab); tribochemical silica airborne-particle abrasion + plasma treated (Tbc_NTP); abraded + plasma treated (Ab_NTP). After a bonding agent (PEKK Bond) was applied to the specimens, each group was divided into 2 subgroups according to the applied veneering resin materials: polymethylmethacrylate (PMMA) and nanohybrid composite resin (NHC, n=10). The specimens were stored in water for 24 hours at 37 °C and subjected to the SBS test by using a universal testing machine, and failure modes were evaluated using a stereomicroscope. Two-way analysis of variance (ANOVA) was performed followed by the Tukey honestly significant difference (HSD) test to statistically analyze the data (α=.05). RESULTS: The 2-way ANOVA showed that surface treatment methods, veneering material, and their interactions were significantly different on the SBS values (P<.001). The highest SBS values were determined for the Tbc and Tbc_NTP treatment groups not only for PMMA (10.71 to 11.63 MPa) but also for NHC (19.80 to 20.60 MPa) veneering resin materials (P<.05). CONCLUSIONS: The bonding capacity of PEKK to the PMMA and NHC veneering resin materials can be significantly improved by using tribochemical silica airborne-particle abrasion alone or with nonthermal plasma surface treatment techniques. Furthermore, using NHC veneering resin material is recommended over PMMA.

Influence of surface sealant agents on the surface roughness and color stability of artificial teeth.

STATEMENT OF PROBLEM: Although various surface sealant agents are available and recommended for chairside polishing procedures, their effect on the surface roughness and color stability of denture teeth is not clear. PURPOSE: The purpose of this in vitro study was to evaluate the effect of sealant agents on the surface roughness and color stability of various denture tooth materials. MATERIAL AND METHODS: Eighty disk-shaped specimens were prepared for each type of denture tooth material (SR Vivodent, PMMA; Vitapan, reinforced-PMMA; SR Phonares II, composite resin). The specimens were assigned to 4 groups according to the surface treatment used (n=20): surface sealant agents (Palaseal; Heraeus Kulzer GmbH, Optiglaze; GC Corp Biscover; Bisco Inc) and a conventional laboratory polishing technique (control group). A thermal cycling procedure was applied for half of the specimens (n=10). The surface roughness (Ra) values of thermocycled and nonthermocycled specimens were measured with a profilometer. The CIELab color parameters of both thermocycled and nonthermocycled specimens were measured with a spectrophotometer at baseline and after 7-day storage in a coffee solution. The color differences were calculated from the CIEDE2000 (ΔE00) formula. Data were statistically analyzed with 3-way ANOVA and the Tukey HSD test (α=.05). RESULTS: The type of tooth material, surface treatment technique, and their interactions were significant for Ra values, and each variable and their interactions were also significant for ΔE00 values (P<.05). Thermal cycling had a significant effect only on ΔE00 values (P<.05). CONCLUSIONS: Palaseal and Optiglaze sealant agents provided smoother and more color-stable denture tooth surfaces than the conventional polishing technique. The use of the Biscover agent with SR Vivodent and Phonares II teeth increased the Ra values. The color of conventionally polished SR Vivodent and Phonares II teeth changed more with thermal cycling.