Effect of argon plasma and Er:YAG laser on tensile bond strength between denture liner and acrylic resin.

STATEMENT OF PROBLEM: The separation of a denture liner from the denture base can be a clinical problem. Different surface treatments to increase the bond have been evaluated, but studies comparing the effect of argon plasma and erbium-doped yttrium aluminum garnet (Er:YAG) laser on the bond between acrylic resin and a denture liner are lacking. PURPOSE: The purpose of this in vitro study was to evaluate the effect of argon plasma and Er:YAG laser treatments on the bond strengths of acrylic resin to 2 denture liners. MATERIALS AND METHODS: Heat-polymerized acrylic resin (Acron Duo) was bonded to silicone soft-liner materials (Molloplast B, n=30; Mollosil, n=30) to create control specimens (n=10), argon plasma treatment (n=10), and Er:YAG laser treatment (n=10). Silicone liners were polymerized on resin specimens. The tensile bond strength test was performed with a crosshead speed of 10 mm/min with a 10-N load until failure. Data were analyzed by using the Kruskal-Wallis test and unpaired t test (α=.05). RESULTS: The laser group showed significantly higher bond strength than the argon plasma group for both Molloplast-B (P=.001) and Mollosil (P<.001). The highest tensile bond strength values were determined in the laser-treated Molloplast-B group (1.325 ±0.119 MPa) while the lowest bond strength values were determined in the Mollosil control group (0.384 ±0.018 MPa). CONCLUSIONS: Argon plasma and Er:YAG laser applications increases the tensile bond strength between soft-liner material and resin. Er:YAG laser treatment results in higher bond strength values than treatment with argon plasma for 1 minute.

The effects of nanofilled resin-based coatings on the physical properties of glass ionomer cement restorative materials.

OBJECTIVES: To determine the effect of two resin-based coatings on the water sorption/solubility and colour change of three conventional and two resin modified glass ionomer cement restorative materials. METHODS: Five glass-ionomer cement (GIC) restorative materials and two nanofilled resin-based coatings were studied. Disc-shaped specimens of each material were prepared and divided into three groups, uncoated and coated with either of the two coatings tested (n = 8). Water sorption and solubility were measured in accordance with ISO 4049 and ISO 6876 instructions, respectively. For colour change, the specimens were immersed in distilled water for 24 h, then immersed for another 24 h and an extra week in the three solutions of lactic acid, coffee, and distilled water. The specimens were subjected to colour measurements, using a spectrophotometer after 24 h and 7 days of immersion. The colour change (ΔE) was calculated using a specific formula. ANOVA tests were used for data analysis. RESULTS: Two-Way ANOVA revealed a significant interaction between materials and coatings for the water sorption/solubility values. Fuji Bulk showed the lowest water sorption/solubility and the coated groups showed a lower mean sorption/solubility and ΔE. The ΔE varied depending on the materials and the solutions. CONCLUSIONS: Coating of GIC restoratives reduced the water sorption/solubility and ΔE of almost all materials with a significant decline in most of the materials. CLINICAL SIGNIFICANCE: Coating of GIC restorations in the oral environment with resin-based coating may protect the restorations from early water sorption/solubility and discolouration.

Influence of beverages and surface roughness on the color change of resin composites.

AIM: The aim of the present study was to determine the degree of surface staining and roughness of resin composites (RC) after finishing and polishing with different methods and immersion in three soft drinks. METHODS: A microhybrid, a nanohybrid, and a hybrid composite were selected. The specimens were prepared and divided into three groups of 36 after 24 hours, and designated as either unpolished or polished using Sof-Lex discs or Enhance point. Each group was further divided into three subgroups, immersed in distilled water, coffee, or cola for 1 week (N = 12). Color change (∆E) was measured by a spectrophotometer after each treatment. The ∆E was calculated using the following formula: ∆E = ([∆L]2+[∆a]2+[∆b]2)1/2. Surface roughness (Ra) was measured after 24 hours and 1 week. To observe the Ra, a scanning electron microscope was used. RESULTS: A moderate correlation between Ra and ∆E was determined. Only coffee caused perceptible ∆E. The effect of Ra on staining was statistically significant (P < .05), but immersion in solutions for 7 days did not increase the Ra of RC. CONCLUSIONS: The highest Ra values were obtained from hybrid RC. The Enhance point created the greatest roughness. Coffee was associated with the greatest ∆E for all materials and polishing methods.

Laser Application to the Root Surface Increases the Bonding Strength of Surface-Treated Prefabricated Glass-Fiber Posts in Teeth with Excessive Substance Loss.

BACKGROUND This study examined the effect of roughening of the root surface using an erbium-doped yttrium aluminum garnet (Er: YAG) laser on the binding strength of teeth undergoing root canal treatment. MATERIAL AND METHODS Ninety single-rooted teeth were used and assigned randomly to 9 groups (n=10 each). Root canals were prepared using the FlexMaster rotary system. An Er: YAG laser was applied to the root canals in Group 1, with no surface treatment of the glass-fiber post. In Group 2, aluminum oxide particles were applied. In Group 3, the laser was applied to the root canals, with Cojet treatment. Group 4 received laser treatment and Clearfil Ceramic Primer. In Group 5, Clearfil Ceramic Primer silane coupling was performed on post surfaces without laser treatment. In Group 6, hydrofluoric acid (HF) application was followed by Clearfil Ceramic Primer cementing of the glass post surfaces with laser application. In Group 7, HF acid treatment was performed without laser. In Group 8, the laser was applied, followed by sanding of post surfaces using Korox 50, and silane coupling with Clearfil Ceramic Primer. In Group 9, the post surfaces were sanded using Korox 50 with laser application to the root canals. The samples were subjected to a push-out experiment. The data were analyzed using Friedman's test and the Wilcoxon signed-rank test. RESULTS A significant difference in bonding strength was found among the groups (p<0.005). CONCLUSIONS Use of an Er: YAG laser in the root canal may be beneficial prior to bonding of glass posts.

Fracture toughness of seven resin composites evaluated by three methods of mode I fracture toughness (KIc).

This study compared the fracture toughness values of seven resin composites and analyzed the consistency of data values using three methods: compact tension, three point and four point bending for Mode I failure. Seven resin composites were selected: Estellite Sigma Quick, Esthet X HD, Filtek Supreme XTE, Heliomolar, Ice, Rok, and Vit-l-escence. For each material, 18 specimens (n=6 for each test) were prepared. Maximum load to failure was recorded using a universal testing machine and fracture toughness was calculated. There was a direct significant correlation among all tested methods. Rok showed the highest and Estelite the lowest KIc values. SEM of the fractured surface of compact tension method showed propagation of the cracks from stresses concentrating at the corner of the notch and the surface of the sample. Four-point test gave the largest range in KIc and was a simple method to discriminate between the resin composite values of KIc.

Adhesion of conventional and simplified resin-based luting cements to superficial and deep dentin.

This study evaluated the bond strengths of conventional (chemically and dual-polymerized) and simplified resin-based luting cements with their corresponding adhesives to superficial dentin (SD) and deep dentin (DD). Recently extracted third molars (N = 70, n = 10 per group) were obtained and prepared for testing procedures. After using their corresponding etchants, primers, and/or adhesive systems, the conventional and simplified cements (Variolink II [group A, conventional], Bifix QM [group B, conventional], Panavia F2.0 [group C, conventional], Multilink Automix [group D, simplified], Superbond C&B [group E, conventional], Clearfil Esthetic Cement [group F, simplified], Ketac-Fil [group G, conventional]) were adhered incrementally onto the dentin surfaces using polyethylene molds (inner diameter 3.5 mm, height 5 mm) and polymerized accordingly. Resin-modified glass-ionomer cement (RMGIC) acted as the control material. Shear bond strengths (1 mm/min) were determined after 500 times of thermocycling. Kruskal-Wallis and Mann-Whitney tests were used to analyze the data (α = 0.05). Bond strength (MPa) results were significantly affected by the cement types and their corresponding adhesive systems (p ≤ 0.05). The shear bond strengths (MPa ± SD) for groups A-G were 14.6 ± 3.8, 18.9 ± 3.9, 5.5 ± 4.5, 3.1 ± 3.6, 1.1 ± 2.5, 15.5 ± 2.6, 7 ± 4.3 and 7.1 ± 5.8, 15.1 ± 7.8, 8.4 ± 7.3, 7.5 ± 7.3, 4.9 ± 5.1, 12.5 ± 2.1, 6 ± 2.6 for SD and DD, respectively. The level of dentin depth did not decrease the bond strength significantly (p > 0.05) for all cements, except for Variolink II (p < 0.05). On the SD, bond strength of resin cements with "etch-and-rinse" adhesive systems (Variolink II, Bifix QM, Super-Bond C&B) showed similar results being higher than those of the simplified ones. Simplified cements and RMGIC as control material showed inferior adhesion to superficial and deep dentin compared to conventional resin cements tested.

Comparison of the effect of storage media on shear punch strength of resin luting cements.

OBJECTIVES: To measure the shear punch strength of eight resin-containing luting cements before and after immersion in acidic solution and ethanol at different temperatures (37 degrees C and 60 degrees C). METHOD: Specimens were prepared from six resin luting cements; Set (SDI), Panavia F (Kuraray), RelyX Veneer (3M/ESPE), VarioloinkII (Ivoclar), Maxcem (Kerr), Nexus2 (Kerr) and two Resin-modified glass-ionomer luting cements (RM-GICs); GC Fuji Plus (GC Corporation), RelyX Luting 2 (3M/ESPE). For each material a total of 114 disc-shaped specimens were prepared. Six specimens were immersed in distilled water for 24 h at 37 degrees C, polished and subjected to baseline measurement for shear punch strength. The remaining 108 specimens were randomly divided into 18 groups of six, and immersed in three solutions; distilled water, 0.01 mol/L lactic acid, and 50% ethanol at 37 degrees C or 60 degrees C, for 1 week, 1 month or 3 months. Specimens were washed, dried and tested for final shear punch strength. RESULTS: Values were material and solution dependent. Values of Nexus 2 and Rely X Veneer are the highest, and Rely X Luting 2 the lowest. Ethanol and lactic acid specimens showed significantly lower values compared with the distilled water specimens. CONCLUSION: The shear punch strengths of the resin-containing luting cements were affected by time and storage solution. While some of the resin luting cements had significantly higher values compared to that of the RM-GICs, there were no significant differences between the RM-GICs and resin cements such as Panavia F and Set.

Fracture strength of indirect resin composite laminates to teeth with existing restorations: an evaluation of conditioning protocols.

PURPOSE: This study evaluated the fracture strength and failure types of indirect resin-based composite laminates bonded to teeth with aged Class III composite restorations that were conditioned according to various protocols. MATERIALS AND METHODS: Maxillary central incisors (N = 60) with window-type preparations received laminates made of a highly-filled resin composite material (Estenia) (10 per group).On the mesial and distal side, Class III cavities (3 x 3 mm) were prepared using ultrasonic burs and filled with resin composite (Quadrant Anterior Shine). The unrestored teeth served as a control group (group 6). All restored teeth (n=50) were thermocycled (5 degrees C to 55 degrees C, 6000X) and subjected to one of the conditioning protocols: (1) air-particle abrasion with alumina particles coated with silica (30-microm SiO2, CoJet)+silanization, (2) air-particle abrasion with alumina particles (50 microm, Al2O3)+silanization, (3) 9.5% hydrofluoric acid (HF) for 90 s (Ultradent)+silanization and (4) protocol of Clearfil Repair Kit, (5) adhesive resin (Quadrant Unibond Sealer). A three-step bonding procedure and dual-polymerizing resin cement (Panavia F 2.0) were employed. The inner surfaces of the laminates were conditioned (CoJet-Sand, 30 mum SiO2) and silanized (ESPE-Sil). All specimens were stored in water at 37 degrees C for one month prior to the fracture test. RESULTS: A significant difference was observed in fracture strength values between the groups (ANOVA, p = 0.0261). The only significant difference was between group 2 (299 +/- 103 N) and group 3 (471 +/- 126 N) (p = 0.0239) (Tukey's test, alpha = 0.05). The majority of failures were type C (35/60) (chipping of the laminate with enamel exposure), followed by type B (21/60) (cohesive failure within the composite laminate). CONCLUSION: The fracture strengths of the laminates tested did not show significant differences, whether they were bonded to existing, aged Class III composite restorations or to intact teeth. The failure types, however, varied between the groups. The lowest strengths were obtained from the air-particle abraded (50 microm, Al2O3) and silanized group.

Sorption and solubility of luting cements in different solutions.

This study examined the solubility, sorption, and dimensional change of eight luting cements in two different solutions: 50% ethanol:water and distilled water. Ten disk specimens were prepared of each material following the manufacturers instructions, and then ground with silicone carbide paper. Sorption and solubility were calculated by weighing the specimens before and after immersion and desiccation. Data were analyzed by two-way ANOVA, Tukey's HSD and Fisher's PLSD tests. GC Fuji Plus and RelyX Luting2 showed the highest values of sorption and solubility both in water and ethanol:water. The percentage changes in volume for Maxcem, Nexus 2, Panavia F, RelyX Veneer, and VariolinkII were considerably smaller than for GC Fuji Plus, RelyX Luting2, and seT in both water and ethanol:water and after desiccation. Stability occurred within 2 weeks for all the eight materials when in water, while GC Fuji Plus, Maxcem, Panavia F and seT took 3 to 4 weeks to stabilize in ethanol:water.

Removable partial denture in a cleft lip and palate patient: a case report.

This clinical report described the oral rehabilitation of a cleft lip and palate patient with removable partial denture. Although implant-supported fixed treatment was presented as part of the optimum treatment plan to achieve the best result, the patient declined this option due to the significant financial burden. Persons with a congenital or craniofacial defect are unique, and oral problems must be evaluated individually to the most ideal treatment. The changes in appearance, function, and psychological wellbeing have an enormous impact on patients' personal lives and are rewarding for the maxillofacial prosthodontist providing this care.

A technique for fabrication of an interim ocular prosthesis.

Several ocular and orbital disorders require surgical intervention that may result in ocular defects. Immediate intervention is required to preserve the anophthalmic socket size and prevent scar tissue contractures that may follow surgery. Unfortunately, immediate fitting of an anophthalmic socket with an artificial eye may not always be possible, and a delayed prosthesis delivery may result in settling and sinking of the prosthesis into the socket, therefore requiring orbital cavity conformation. This article presents a short review of the most commonly used techniques for processing an ocular prosthesis, while suggesting a practical transition to the application of some of them. A technique for fabricating a custom-made provisional ocular prosthesis using digital imaging technology is described. This technique may be considered in order to avoid costly procedures that might be required as a result of delayed artificial eye insertion. The technique described in this article provides a cost-effective choice for optimal orbital cavity conformation and serves as a diagnostic aid for predicting the patient's compliance to ocular prosthetic treatment. The esthetic advantages and the relative ease of fabrication of this interim prosthesis allow it to be considered a first step in the management of untreated anophthalmic sockets.

Effect of storage duration on the hardness and tensile bond strength of silicone- and acrylic resin-based resilient denture liners to a processed denture base acrylic resin.

STATEMENT OF PROBLEM: Two potential problems commonly identified with a denture base incorporating a resilient liner are a failure of the bond between the acrylic resin and resilient liner material and a loss of resiliency of the resilient liner material over time. PURPOSE: This investigation evaluated the effect of storage duration on the tensile bond strength and hardness of acrylic resin- and silicone-based resilient liners that were either heat- or autopolymerized onto denture base acrylic resin. MATERIAL AND METHODS: The denture liners investigated were a definitive acrylic resin-based heat-polymerized (Vertex Soft), interim acrylic resin-based autopolymerized (Coe-Soft), definitive silicone-based heat-polymerized (Molloplast-B), and definitive silicone-based autopolymerized (Mollosil Plus) resilient liner. The resilient liners were processed according to manufacturers' instructions. The resilient liner specimens for tensile bond strength testing (n=10) were 10 x 10 x 3 mm and were processed between 2 polymethyl methacrylate (PMMA) (Meliodent) blocks (40 x 10 x 10 mm). The resilient liner specimens for hardness testing (n=10) were 20 mm in diameter and 12 mm in height. Specimen shape and liner thickness were standardized. Specimens were stored for 1 day, 1 week, or 1, 3, or 6 months in water at 37 degrees C. Tensile bond strength was measured in a universal testing machine at a crosshead speed of 20 mm/min, and hardness was measured using a Shore A durometer. Two-way ANOVA and Tukey HSD tests were used to analyze the data (alpha=.05). RESULTS: The results indicated that there were significant differences both in the hardness and bond strength values of resilient liner materials. The definitive silicone-based heat-polymerized (Molloplast-B) resilient liner had significantly higher bond strength and lower hardness values than the others. Prolonged exposure to water produced significantly higher hardness values and lower bond strength values. CONCLUSIONS: Within the limitations of this in vitro study, specimens of resilient liners immersed in water demonstrated significantly (P<.001) lower bond strength values and higher hardness values over time.

Oral rehabilitation of a patient with hypoplastic amelogenesis imperfecta: a case report.

To report a case of oral rehabilitation of a patient diagnosed with hypoplastic amelogenesis imperfecta. A 18-year-old female with hypoplastic amelogenesis imperfecta presented for prosthodontic treatment to eliminate tooth sensitivity while enhancing esthetics and restoring masticatory function. Treatment included, lengthening of the maxillary and mandibular clinical crowns, and placement of metal-ceramic fixed partial dentures. The 1-year recall examination revealed no pathology associated with the rehabilitation, and the patient's esthetic and functional expectations were satisfied. For successful prosthodontic therapy, the clinician should be aware of all condition of patient.

Effect of denture cleansers on the hardness of heat- or auto-cured acrylic- or silicone-based soft denture liners.

PURPOSE: To investigate the effect of short (24 hours) and long term (6 months) exposure to a variety of commercially available denture cleanser solutions on the hardness of a variety of acrylic- and silicone-based resilient liners that were either heat- or auto-cured. METHODS: The denture liners investigated were an acrylic-based heat-cured (Vertex Soft), acrylic-based auto-cured (Coe-Soft), a silicon-based heat-cured (Molloplast-B) and silicon-based auto-cured (Mollosil Plus) resilient liners. Cylindirical specimens (20 mm diameter, 12 mm high) were made of each material, using 10 replications for each test condition. Immersion solutions consisted of distilled water (control), and those based on alcohol, chlorhexidine, or an alkaline peroxide (Dermacol, aqueous chlorhexidine, Steradent) as a major active component. Specimens were fabricated according to manufacturer directions. Shore-A durameter hardness readings were taken on all specimens at each time interval and then compared statistically using four-way ANOVA and Tukey HSD (alpha = 0.05). RESULTS: The results of this study indicated that, compared with distilled water, significant effect on the hardness of the specimens were found after immersion in all of the denture cleanser solutions at 24 hours and at 6 months. Specimens immersed in chlorhexidine showed higher and significant hardness changes than those immersed in other cleanser solutions. Also, it was determined that hardness of resilient liner materials increased with time and significantly higher hardness was recorded at 6 months for the auto-cured specimens compared with their heat-cured counterparts.

Effect of storage duration on tensile bond strength of acrylic or silicone-based soft denture liners to a processed denture base polymer.

OBJECTIVE: To investigate the effect of storage duration on the tensile bond strength of acrylic and silicone-based denture base materials with liners either heat-cured or auto-cured. MATERIAL AND METHODS: The denture liners investigated were Vertex soft (acrylic-based, heat-cured), Coe soft (acrylic-based, auto-cured), Molloplast-B (silicone-based, heat-cured), and Mollosil plus (silicone-based, auto-cured). The soft liner specimens were 10 x 10 x 3 mm and were processed between two PMMA blocks. They were tested following immersion in water at 37 degrees C for 1 day, 1 week, and 1, 3, and 6 months. Tensile bond strength was measured using a universal testing machine (Testometric Micro 500) at a crosshead speed of 20 mm/min (n = 10 specimens per experimental group). Multiple ANOVA and Tukey HSD were used to analyse the data at a pre-set alpha of 0.05. RESULTS: The results indicate that the tensile bond strength of acrylic-based soft liners is greater than that of silicone-based materials. The bond strength of all lining materials decreases with storage duration; the decrease being greatest for the acrylic-based soft liners. The decrease in bond strength of the auto-cured materials is greater than that of the heat-cured products. CLINICAL SIGNIFICANCE: Comparison of the materials in this study indicates that the silicone-based, heat-cured soft liner is superior, based on the tensile bond strength property. Use of silicone-based, heat-cured soft liners may provide better clinical success over a long period. These laboratory results need to be verified by clinical testing.