Effect of ultraviolet light irradiation on bonding of experimental composite resin artificial teeth

Effect of ultraviolet irradiation treatment on shear bond strength between polymethyl methacrylate and cobalt-chromium-molybdenum alloy

We aimed to elucidate the effects of ultraviolet (UV) irradiation on the shear bond strength (SBS) between heat-cured polymethyl methacrylate (PMMA) and a Co-Cr-Mo alloy. Disk-shaped Co-Cr-Mo alloy prepared by casting were subjected to different UV treatment times (0, 15, and 30 min). To determine the effect of UV treatment on surface properties of the alloy, surface roughness, wettability, and chemical compositions were analyzed. To evaluate the SBS, cylindrical PMMA was bonded to the UV-treated alloy, and subsequently subjected to the SBS test after 24 h of storage at room temperature or following 10,000 thermal cycles (n=10/group). After the UV treatment, the surface roughness remained unchanged, but oxidation resulted in the surface exhibiting greater hydrophilic characteristics. The UV-treated group showed significantly higher SBS values than those of the non-treated group (p<0.001). These results suggested that UV treatment-mediated oxidation improved the bond strength between PMMA and Co-Cr-Mo alloy.

Effect of Photoactivation by Ultraviolet Light on Bond Strength of Composite Veneer on Stainless Steel Crowns—An In Vitro Study

Aim

The aim of this study is to determine the effect of ultraviolet irradiation on the bond strength of composite veneer adhered to the SSCs.

Materials and methods

Seventy anterior typhodont teeth (API, New Delhi, India) were randomly divided into two groups (N = 35/group) to be crowned with 70 maxillary left central incisor SSCs, size no. 3 (3MESPE, St. Paul, USA). The crowns were adjusted and cemented with the glass ionomer cement (type I, Ivoclar Vivadent, New York, USA). The labial surfaces of the experimental group were exposed to UV irradiation for 80 minutes using the UV chamber (Easy UV Chamber, India) with 2 UV lamps that produced 30 W of power to induce photoactivation. Standardized composite blocks (Ivoclar Vivadent, Gurgaon, India) of 4 × 4 × 1 mm were fabricated using Teflon molds and light cured for 60 seconds. The samples were fixed in the acrylic resin (NicTone62),with a label bearing the number of each sample. The samples were stored in a dry medium for 24 hours and tested using a universal testing machine.

Results

The mean shear bond strength in the non-UV group was 26.03 ± 9.42 MPa, while in the UV group, it was 35.10 ± 14.80 MPa. Thus, there was a statistically significant difference in the mean value of the shear bond strength between the non-UV and UV groups. The shear bond strength in the UV group is much higher as compared with the non-UV group.

Conclusion

Based on this study's results, the following conclusion can be made: ultraviolet irradiation of pediatric stainless steel crowns was found to significantly increase the shear bond strength of composite resin.

Clinical significance

UV irradiation could provide suitable adhesion of composite resins to stainless SSCs, leading to in-office veneering of SSCs.

How to cite this article

Sharma A, Kulkarni S, et al. Effect of Photoactivation by Ultraviolet Light on Bond Strength of Composite Veneer on Stainless Steel Crowns—An In Vitro Study. Int J Clin Pediatr Dent 2019;12(1):50–52.

Evaluation of three different decontamination techniques on biofilm formation, and on physical and chemical properties of resin composites

OBJECTIVES

This study evaluated three different sterilization/disinfection techniques for resin composites on bacterial growth and surface modification after decontamination.

METHODS

Two resin composites were sterilized/disinfected with three different techniques: UV light, 1% chloramine T, and 70% ethanol. Four different times were used for each technique to determine the shortest time that the solution or UV light was effective. The influence of sterilization/disinfection technique on bacterial growth was evaluated by analyzing the metabolic activity, using the AlamarBlue™ assay, bacterial viability, and SEM images from biofilms of Streptococcus mutans. The surface change, after the process, was analyzed with ATR/FTIR and SEM images. The solutions used for decontamination (1% chloramine-T and 70% ethanol) were analyzed with ¹ H-NMR to identify any resin compounds leached during the process.

RESULTS

One minute of decontamination was efficient for all three methods tested. Chloramine-T increased the surface porosity on resin composites, no changes were observed for UV light and 70% ethanol, however, ¹ H-NMR identified leached monomers only when 70% ethanol was used. No chemical change of the materials was found under ATR/FTIR analyses after the decontamination process. Chloramine-T, with no previous wash, increased the bacterial viability for both resin composites and increased the bacterial metabolism for the resin composite without fluoride.

CONCLUSION

UV light had no interference on the resin composites properties tested using 1 min of exposure compared to the other decontamination methods. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 945-953, 2018.

Effect of ultraviolet light irradiation on bond strength of fiber post: Evaluation of surface characteristic and bonded area of fiber post with resin cement

OBJECTIVE

Fiber post is cemented to a root canal to restore coronal tooth structure. This research aims to evaluate the effect of ultraviolet (UV) irradiation on bond strength of fiber post with resin cement.

MATERIALS AND METHODS

A total of 40 of the two types of fiber posts, namely, FRC Prostec (FRC) and Fiber KOR (KOR), were used for the experiment. UV irradiation was applied on top of the fiber post surface for 0, 15, 20, and 30 min. The irradiated surface of the fiber posts (n = 5) were immediately bonded with resin cement (Rely X U200) after UV irradiation. Shear bond strength (SBS) MPa was measured, and the dislodged area of post surfaces was examined with scanning electron microscopes. Changes in surface roughness (Ra) of the FRC group after UV irradiation were observed (n = 3) using atomic force microscopy. Data of SBS were statistically analyzed using one-way analysis of variance, followed by multiple comparisons (P < 0.05).

RESULTS

SBS was significantly higher for 20 min of UV irradiation of the FRC group while significantly higher SBS was observed with 15 min of UV irradiation of the KOR group. Resin cement was more evident (cohesive failure) on the dislodged post surface of the UV treated groups compared with the control. The surface roughness of the FRC post was Ra = 175.1 nm and Ra = 929.2 nm for the control and the 20 min group, respectively.

CONCLUSIONS

Higher surface roughness of the UV irradiated group indicated formation of mechanical retention on the fiber post surface. Evidence of cohesive failure was observed which indicated higher SBS of fiber post with the UV irradiated group.

Effect of ultraviolet light irradiation and sandblasting treatment on bond strengths between polyamide and chemical-cured resin

The aim of this study was to evaluate the effects of ultraviolet light (UV) irradiation and sandblasting treatment on the shear bond strength between polyamide and chemical-cured resin. Three types of commercial polyamides were treated using UV irradiation, sandblasting treatment, and a combining sandblasting and UV irradiation. The shear bond strength was measured and analyzed using the Kruskal-Wallis test (α=0.05). Comparing shear bond strengths without surface treatment, from 4.1 to 5.7 MPa, the UV irradiation significantly increased the shear bond strengths except for Valplast, whose shear bond strengths ranged from 5.2 to 9.3 MPa. The sandblasting treatment also significantly increased the shear bond strengths (8.0 to 11.4 MPa). The combining sandblasting and UV irradiation significantly increased the shear bond strengths (15.2 to 18.3 MPa) comparing without surface treatment. This combined treatment was considered the most effective at improving the shear bond strength between polyamide and chemical-cured resin.

Effect of ultraviolet light irradiation period on bond strengths between fiber-reinforced composite post and core build-up composite resin

The aim of the present study was to characterize the effects of the ultraviolet light (UV) irradiation period on the bond strength of fiber-reinforced composite (FRC) posts to core build-up resin. Three types of FRC posts were prepared using polymethyl methacrylate, urethane dimethacrylate, and epoxy resin. The surfaces of these posts were treated using UV irradiation at a distance of 15 mm for 0 to 600 s. The pull-out bond strength was measured and analyzed with the Dunnett's comparison test (α=0.05). The bond strengths of the post surfaces without irradiation were 6.9 to 7.4 MPa; those after irradiation were 4.2 to 26.1 MPa. The bond strengths significantly increased after 15 to 120-s irradiation. UV irradiation on the FRC posts improved the bond strengths between the FRC posts and core build-up resin regardless of the type of matrix resin.

Bonding of acrylic denture teeth to MMA/PMMA and light-curing denture base materials: the role of conditioning liquids

OBJECTIVES

The connection between resin denture teeth and the denture base is essential for the integrity of partial and full dentures. The aim of the present study was to analyse the bond strength of acrylic denture teeth to two light curing denture base materials compared to the gold-standard (MMA/PMMA) using different conditioning liquids.

METHODS

The ridge laps of 220 identical denture teeth were ground and pre-treated using different conditioning liquids (MMA, an experimental conditioning liquid as well as the two commercially available liquids Palabond and Versyo.bond). The denture base materials (PalaXpress, Versyo.com, Eclipse) were applied using a split mould to obtain tensile bond strength specimens of identical shape. Ten specimens per test group were either stored in water for 24h or thermocycled (5000×, 5-55°C) prior to tensile bond strength testing (cross-head speed 10mm/min). Data was subjected to parametric statistics (α=0.05).

RESULTS

The three-way ANOVA revealed a significant influence of the material, pre-treatment as well as the storage. PalaXpress showed the highest bond strength (24.3MPa) of all materials tested after TC, whereas the use of MMA led to the most constant results. Lower values were recorded for Versyo.com (17.5MPa) and Eclipse (10.4MPa) bonded with Versyo.bond.

CONCLUSIONS

The results indicate that MMA/PMMA based denture base resins provide reliable and durable bond strength to acrylic denture teeth. Using light-curing denture base materials requires the application of appropriate conditioning liquids to obtain acceptable bond strength. The use of MMA affects bond strength to light-curing denture base materials.

CLINICAL SIGNIFICANCE

The pre-treatment of denture teeth is critical regarding their bond-strength to denture base materials and in turn for the integrity of removable full and partial dentures. Light-curing denture base resins are more sensitive to the correct tooth pre-treatment compared to conventional MMA/PMMA materials, requiring specific conditioning liquids.

Effect of filler type and polishing on the discoloration of composite resin artificial teeth

In this study, the effects of filler type and polishing on the discoloration of composite resin artificial teeth were examined. Four types of experimental resins were prepared: one was a matrix resin, while the others were composite resins containing three different types of fillers (nano-sized silica filler with or without silanization, and prepolymerized filler). Specimens were immersed in distilled water, coffee, red wine, or curry. Color change after immersion was measured using a colorimeter. Color difference values (delta E) and changes in translucency parameter (delta TP) were statistically analyzed using three-way ANOVA and Tukey's comparison. On the influence of the polishing factor, statistically significant differences were neither observed in delta E nor delta TP between polished and non-polished tooth surfaces. On the contrary, the influences of filler type and discoloration medium, and their interaction thereof, were significant. With unsilanized filler, the delta E value of composite resin artificial teeth was significantly increased.