Microtensile bond strengths of adhesively bonded polymer-based CAD/CAM materials to dentin.

This in vitro study aimed to evaluate the effect of two different polymer-based CAD/CAM materials; resin-nano ceramic (Lava Ultimate [LVU]) and composite (CERASMART [CS]), their different surface pre-treatments, and use of different resin cements on the µTBS of adhesively bonded CAD/CAM onlays to dentin. CAD/CAM materials were cut into slabs and divided into five groups according to the surface pre-treatments applied: Silane Primer, OptiBond XTR adhesive, Silane Primer+OptiBond XTR adhesive, Single Bond Universal (SBU), and RelyX Ceramic Primer+SBU. The LVU and CS specimens were bonded to the mid-coronal dentin of 50 non-carious human molars using NX3 resin cement with OptiBond XTR or RelyX Ultimate with SBU. µTBS was evaluated after 5,000 thermocycling and analysed with three-way-ANOVA and post-hoc Tukey's tests (p<0.05). The µTBS was significantly influenced by the type of CAD/CAM material (p<0.0001) surface pre-treatments (p<0.05) and resin cements (p<0.05). Regardless of the pre-treatments and resin cements, bonding of the composite CAD/CAM material to dentin was higher than the resin nano-ceramic material.

Effect of bleaching on microhardness of esthetic restorative materials.

This study evaluated the effect of a high-concentration carbamide peroxide­containing home bleaching system (Opalescence PF) and a hydrogen peroxide­containing over-the-counter bleaching system (Treswhite Supreme) on the microhardness of two nanocomposites (Filtek Supreme XT and Premise) and leucite-reinforced glass ceramic (Empress Esthetic), glass ceramic (Empress 2 layering), and feldspathic porcelain (Matchmaker MC). A total of 100 specimens, 20 of each kind of the restorative materials, 2 mm in thickness and 10 mm in diameter, were fabricated. Then the specimens were polished with SiC paper and 1 µm alumina polishing paste. After polishing, porcelain specimens were glazed in accordance with the manufacturer's instructions. Each type of restorative material was then randomly divided into two groups (n=10), and the specimens were treated with either Opalescence PF or Treswhite Supreme. The microhardness of the specimens before bleaching (baseline) and after bleaching was determined using a digital microhardness tester. Data were analyzed using the Mann-Whitney U-test and the Wilcoxon test. Opalescence PF significantly influenced the hardness of all the restorative materials. Statistically significant decreases with respect to before bleaching were found for Premise (p=0.005), Empress Esthetic (p=0.003), Empress 2 layering (p=0.005), and Matchmaker-MC (p=0.003), whereas a statistically significant increase was observed in Filtek Supreme XT (p=0.028). The difference in the microhardness values between before and after bleaching using Treswhite Supreme was statistically significant only for Premise (p=0.022). High-concentration carbamide peroxide­containing home bleaching may affect the microhardness of restorative materials.

Long-term provisional anterior tooth replacement using fiber-reinforced composite and avulsed tooth crowns as pontics.

The loss of anterior teeth due to trauma requires immediate attention for function and esthetics. While implant- supported or conventional fixed prostheses may be the treatments of choice for adults, relatively noninvasive and reversible provisional procedures for tooth replacement are necessary for adolescents. In recent years, developments in fiber and composite technology offer a conservative treatment approach to restore the anterior edentulous space as a fixed provisional tooth replacement. This case report presents the chairside procedures of anterior tooth replacement in an adolescent using the avulsed tooth crowns as pontics which were bonded to teeth on either side of the edentulous space and reinforced with a preimpregnated fiber.

Bond strengths of three different dentin adhesive systems to sclerotic dentin.

The two-fold aims of this study were: (1) to evaluate the microtensile bond strengths of different adhesive systems to sclerotic and sound palatal dentin; and (2) to observe the respective resin-dentin interfaces. Thirty extracted human incisor teeth were divided into two groups. Group I comprised sclerotic defects in the palatal zone. Group II comprised sound palatal dentin surfaces as control. Each group (n=15) was divided into three subgroups according to dentin adhesive systems: self-etch (Clearfil SE Bond), total-etch (Scotchbond Multi-Purpose Plus), and glass ionomer (Reactmer Bond) adhesive systems. The specimens were subjected to tensile forces. Obtained data were analyzed by two-way ANOVA and post hoc Duncan's test. Fracture sites and resin-dentin interfaces were observed using a light microscope and SEM. With sound dentin, Clearfil SE Bond showed a significantly higher bond strength than the other adhesives (p < 0.05). With sclerotic dentin, although there were no significant differences in bond strength among the adhesives groups (p > 0.05), the bond strength values of Clearfil SE Bond and Scotchbond Multi-Purpose Plus were significantly decreased. On resin-dentin interface observation, different images were presented by different bonding systems.

Bonding to sound vs caries-affected dentin using photo- and dual-cure adhesives.

This study aimed to evaluate the microtensile bond strength (microTBS) of photo- and dual-cure adhesives to sound and caries-affected dentin using total- and self-etch techniques. Human third molars with occlusal caries were prepared as previously described by Nakajima and others (1995). Dentin surfaces were bonded with Optibond Solo Plus (Kerr; photo-cure adhesive) or Optibond Solo Plus + Dual-cure activator (Kerr; dual-cure adhesive) with total- and self-etch technique. Clearfil AP-X (Kuraray) was used for composite buildups. Following storage in distilled water at 37 degrees C for 24 hours, the teeth were sectioned into 0.7-mm thick slices to obtain sound and caries-affected dentin slabs, then trimmed to form hour glass shapes with a 1 mm2 cross-sectional area. The specimens were subjected to microtensile testing using EZ-test (Shimadzu) at 1 mm/minute. Data were analyzed using three-way ANOVA and Student's t-Test (p<0.05). Bond strengths to sound dentin with photo- and dual-cure adhesives using total- and self-etch techniques were significantly higher than those to caries-affected dentin. Dual-cure adhesive significantly decreased bond strengths both to sound and caries-affected dentin. The total-etch technique showed no beneficial effect on caries-affected dentin compared with the self-etch technique. Scanning electron microscopic observation of the resin-dentin interfaces revealed that hybrid layers in caries-affected dentin were thicker than those observed in sound dentin with photo- and dual-cure adhesives. Resin infiltration into dentinal tubules of caries-affected dentin was hampered by the presence of mineral deposits.

Effect of tooth age on microtensile bond strength of two fluoride-releasing bonding agents.

PURPOSE: The purpose of this study was to evaluate the effect of age of dentin and enamel on the microtensile bond strengths of a glass-ionomer based, all-in-one, single-step, self-etching adhesive system (Reactmer Bond, RB) and an antibacterial, two-step self-etching primer system (ABF Bond, ABF). MATERIALS AND METHODS: Extracted molars from 3 age groups (20 to 25, 35 to 40, and 50 to 55 years) were used. Enamel was removed from the occlusal surfaces of the teeth, and the entire flat surfaces were covered with composite resin (4 mm in height) following application of bonding agents. The bonded specimens were thinly sectioned parallel to the long axis of the tooth into 0.87 +/- 0.03 mm2 rectangular sections, resulting in 6 to 7 enamel specimens and 10 to 15 dentin specimens per tooth. The specimens were subjected to the microtensile test at a crosshead speed of 1 mm/min. The data were analyzed by Univariate ANOVA, Tukey HSD, and regression analysis. RESULTS: The bond strength of ABF to both enamel and dentin was higher than the bond strength of RB. Bond strengths of ABF to dentin were significantly higher than the bond strengths to enamel (p < 0.05). The 35- to 40-year age group of ABF showed the highest bond strength of all. In RB dentin groups, 34% of specimens showed cohesive failure in composite resin material. CONCLUSION: Bond strength values to enamel were not affected by age of teeth in either bonding system. Dentinal bond strength using ABF changed according to age of the teeth. Age did not affect bond strength values of RB to dental hard tissues. However, the high number of cohesive failures in Reactmer paste indicated low tensile strength of the material.

Physical properties of different composites.

The purpose of this study was to determine the flexural strength (FS), flexural modulus (FM), depth of cure (DC), polymerization shrinkage (PS), and microhardness (VH) of the following composites: Two packable composites--Filtek P-60 and Solitaire 2; One ion-releasing composite--riston AT; and Two hybrid composites--Charisma and Filtek Z-250. Data of the different tests conducted were obtained as follows: FS and FM data were determined with a universal-testing machine; Polymerization shrinkage was determined using the apparatus of Watts and Cash; Depth of cure was measured with a micrometer (Mitotuyo, UK); and Microhardness was measured with a Shimadzu Microhardness tester (500 g, 15 seconds). All data of the different tests were statistically analyzed by one-way variance analysis (ANOVA), which yielded the following results: Filtek Z-250 showed the statistically highest flexural strength and modulus values. Solitaire 2 exhibited the highest shrinkage, while the volumetric shrinkage results of Filtek Z-250 and Filtek P-60 ranked the lowest. For depth of cure, there were no statistically significant differences among all materials tested (p<0.05). Microhardness results revealed the following tendency: Filtek Z-250 = Filtek P-60 > Ariston AT = Solitaire 2 = Charisma.

Reattachment of a fractured maxillary tooth: a case report.

A 14-year-old male patient reported with a horizontal fracture of almost the entire crown of a maxillary incisor, extending subgingivally at the palatal side. After root canal therapy and electrosurgery, the tooth fragment was reattached using a total-etch dentin-bonding system and a hybrid composite. Due to enamel cracks and the necessity for more retention, the labial surfaces of the teeth were veneered with a micro-filled composite. The clinical situation of the reattached teeth was confirmed successful by radiographic and photographic assessment after 1, 3, 6, and 12 months. The restoration of an anterior tooth with original tooth fragment in young patients has advantages over conventional composite or prosthetic restorations. However, reattached teeth with fracture extending subgingivally, require long-term follow-up.

In vitro effect of cavity disinfectants on the bond strength of dentin bonding systems.

OBJECTIVE: To evaluate the effect of two cavity disinfectants, a 2% chlorhexidine and a 1% benzalkonium chloride solution, on the shear and tensile bond strengths of dentin bonding systems to dentin. METHOD AND MATERIALS: Superficial dentin was exposed from 84 freshly extracted human third molars. The teeth were randomly assigned to two main groups according to the bonding agent used, either One Step or Optibond Solo. Each dentin bonding system had six test groups (three for shear, three for tensile testing), and each test group had a control and two cavity disinfectant groups. In the control groups, dentin bonding systems were applied after etching the dentin, whereas in the cavity disinfectant groups, dentin was conditioned and treated for 20 seconds with the disinfectants before applying the dentin bonding systems. A hybrid resin composite then was applied to all treated samples. After storage in distilled water at 37 degrees C for 24 hours, shear and tensile tests were performed. Data were analyzed using Kruskall-Wallis and Mann-Whitney U tests. RESULTS: The mean shear and tensile bond strengths of One Step and Optibond Solo were not significantly different from each other, and the cavity disinfectants also had no significant effects on shear and tensile bond strength values versus the controls. CONCLUSION: The results indicate that the use of 2% chlorhexidine and 1% benzalkonium chloride solutions as cavity disinfectants after etching the dentin did not affect the shear and tensile bond strengths of One Step and Optibond Solo.

Wear and microhardness of different resin composite materials.

This study determined the three-body abrasive wear resistance of two packable composites (P-60; Solitaire 2), an ion-releasing composite (Ariston AT), a hybrid composite (Tetric Ceram) and an ormocer (Admira). The study also looked at the correlation between wear resistance and hardness of the composites. Three-body wear testing was performed using an ACTA wear machine with 15 N contact force using millet seed as the third body. Wear depth (microm) was measured by profilometry after 200,000 cycles. The hardness test was performed using a digital microhardness tester (load: 500 g; dwell time: 15 seconds). The data were analyzed by using Kruskal Wallis (p < 0.05). There were statistically significant differences among the three body abrasive wear of the composites. The ranking from least to most were as follows: Filtek P-60 < Solitaire 2 < Ariston AT < Tetric Ceram < Admira. Filtek P-60 showed the highest microhardness value. No other significant differences in hardness were observed among the different resin composites (P-60 > AristonAT = Tetric Ceram = Solitaire 2 = Admira). The results of this study indicate that there are significant differences in the wear resistance of the resin composites. The correlation between hardness and wear was significant with a correlation coefficient of r:-0.91. A significant negative correlation exists between hardness and three-body wear of resin composites.

Polymerization shrinkage and microleakage in Class II cavities of various resin composites.

This study investigated the polymerization shrinkage of restorative materials and microleakage in the proximal box of Class II restorations. Twenty caries free extracted human molars were prepared on the mesial and distal, making 40 slot cavities. Groups (n=10) were classified as: Group 1: Single bond/Filtek Z-250; Group 2: Single Bond/Filtek Flow/Filtek Z-250; Group 3: Admira Bond/Admira; Group 4: Ariston Liner/Ariston. Dentin bonding systems and resin composites were applied according to the manufacturer's instructions. The specimens were stored in distilled water for one week at 37 degrees C, thermocycled (5 degrees-55 degrees C x 2000), stained with 50% aqueous silver nitrate, immersed in a diluted developer solution (24 hours), rinsed and sectioned in two pieces with a low speed saw (Isomet). Dye penetration (Score 0-4) was determined separately at the occlusal enamel margin and cementoenamel junction. The volumetric polymerization shrinkage of materials was determined with the apparatus of Watts and Cash (Watts Cash, 1991) for 300 seconds. Polymerization shrinkage results were as follows: Filtek Flow (3.5% +/- 0.1) > Admira (2.1% +/- 0.1) = Ariston AT (2.3% +/- 0.1) > Filtek Z-250 (1.8% +/- 0.1) (One-way Anova, post hoc Bonferroni test at p = 0.05 level). No statistical difference was found at the enamel margins for any of the materials (Score 0-1). At the cemento-enamel junction, all test groups showed significantly higher microleakage when compared to the enamel margins (Kruskal-Wallis test, Mann-Whitney U). Dye penetration results at dentin were as follows: Filtek Flow + Filtek Z-250 = Admira < Ariston AT = Filtek Z-250. microleakage than the ion-releasing and hybrid composites lined only with bonding agent at the cementoenamel junction in Class II cavities.

Reducing microleakage in composite resin restorations: an in vitro study.

The purpose of this in vitro study was to evaluate the effect of a resin lining on microleakage around composite resin restorations. Standard slot cavities were prepared on the approximal surfaces of 48 extracted human molar teeth. The cavities were restored with two conventional or two condensable composite resins, placed with or without a flowable composite resin lining. The teeth were subjected to thermal stress and immersed in dye solution. Dye penetration was viewed with both a stereomicroscope and a scanning electron microscope. Flowable resin lining material under condensable composites may be beneficial in reducing microleakage around cervical margins.