Search

Objective: The objective of this study was to evaluate the influence of delayed light curing on a dual-cured composite resin on cuspal deflection, microleakage, and enamel cracks. Method and materials: Forty-eight standardized Class 2 cavities were prepared in maxillary third molars and restored with a dual-cure composite resin (Core-X Flow) in bulk-fill technique. The samples were divided into four groups (n = 12) and either self-cured (1) or light cured immediately (2), with 1 minute (3) or 2 minutes of delay (4) after placement. Cuspal deflection was measured before preparation, 6 minutes after placement, after 24 hours, and after 120 days of storage and thermocycling. The margins of the restorations were examined under a stereo microscope after 24 hours and 120 days. Samples were immersed in a 0.2% basic fuchsin solution for 24 hours at room temperature and then sectioned vertically and mesiodistally, and dye penetration and enamel cracks were recorded under a stereomicroscope using a scoring system. Results: Six minutes after placement the cuspal deflections were between 20 ± 2.1 µm and 39.3 ± 1.9 µm. After 120 days the cuspal deflection in all groups was reduced to almost complete recovery, while the percentage of perfect margin decreased. Differences in microleakage, dye penetration, and enamel cracks were observed between different locations but not between the groups. Statistical analysis did not show a correlation between cuspal deflection, margin quality, or enamel cracks. Conclusion: A short delay in light curing of a dual-cure composite resin could significantly reduce the initial cuspal deflection measured 6 minutes after light curing, thereby probably reducing the polymerization shrinkage stress. However, the curing mode did not significantly influence microleakage and enamel cracks. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this prospective study was to evaluate the clinical performance of the restorative material Ceram.X in combination with an experimental one-bottle etch-and-rinse adhesive (K-0127). Materials and Methods: A single operator placed two Class I or II restorations in molars of 43 patients. One molar was restored with Ceram.X/K-0127 (Dentsply DeTrey), the other one with Tetric Ceram/Syntac Classic (Ivoclar Vivadent). At baseline, after one, two, and four years the restorations were evaluated by a second dentist using modified Ryge's criteria. After four years, 27 patients were examined. Results: In one patient, both restorations (Class II) had to be removed for root canal treatment due to pulpitis. Another Class II Ceram.X restoration (3.8%; 4.3% [1 of 23] of Class II restorations) showed score C with regard to wear/anatomical form. Thus, the cumulative failure rate was 7.4% in the Ceram.X group (8.3% of Class II restorations [2 of 24]) and 3.7% in the Tetric Ceram group (4.2% of Class II restorations [1 of 24]). Furthermore, three restorations (11.5%) in each group showed score B for anatomical form and marginal integrity. Slight marginal discoloration (score B) was found at five Ceram.X restorations (19.2%) and four Tetric Ceram restorations (15.4%). Two restorations (7.7%) in each group showed slight changes in color stability (score B). No sensitivity, recurrent caries, or changes in surface texture were recorded after four years. No statistically significant differences were found between the two restorative materials (p > 0.05). Conclusion: After four years of clinical service, 92.6% of Ceram.X/K-0127 and 96.3% of Tetric Ceram/Syntac Classic restorations performed clinically well. [ABSTRACT FROM AUTHOR]

Purpose: Matrices of adhesive restorative materials and repair procedures may both influence bond strength of repaired adhesive materials. This study examined the bond strength of adhesive filling materials to mature adhesive materials after pretreatment with Co-Jet, Monobond S, and Silibond. Materials and Methods: A hybrid composite (Tetric Ceram), a polyacid-modified composite resin (Dyract), and an ormocer (Definite) and their corresponding bonding agents were tested in combination with the repair systems. Restorative materials were placed in molds and polymerized. In group A (control), homologous materials were applied on the polymerized surface directly. In group B, homologous filling materials were placed onto the respective material with the corresponding bonding agent. In group C, adhesive repair filling material was applied after solely pretreating with the repair systems. In group D, the restorative material was applied after pretreatment with the repair systems and application of the corresponding bonding agent. Each subgroup consisted of 20 specimens. The shear bond strength of the samples was measured in a universal testing machine according to the test procedure ISO 10477. Results: The significantly best bond strength of repair filling material on Tetric was achieved by pretreating with Co-Jet followed by application of the corresponding bonding agent (25.5 ± 5.4 MPa, p<0.05). A single application of the bonding agent or use of Monobond with bonding agent also yielded bond strengths of 20 MPa or more on Tetric. For Dyract or Definite, bond strengths of 15.5 ± 5.3 MPa or less were achieved with the different repair procedures. Conclusion: Successful pretreatment of hybrid composites for repair can be achieved by application of Co-Jet followed by the corresponding bonding material, whereas sufficient repair of ormocers and polyacid-modified resin composites is limited. [ABSTRACT FROM AUTHOR]

Purpose: To compare the influence of in vivo and in vitro conditions on marginal and internal adaptation of composite restorations using three adhesive systems. Methods: 60 human teeth were distributed among three material groups. In each root, three Class V cavities were prepared and filled with the same material, one in vivo and, after extraction, one in perfused and one in not-perfused dentin specimens. Results: Evaluation of gap formation at the composite/dentin interface with SEM revealed no significant differences between marginal and internal adaptation. Adaptation data were different according to the materials used (P= 0.002), and to experimental conditions (P= 0.04). According to the gap frequency concerning experimental conditions, it was concluded that in vivo adaptation of composite restorations to dentin seemed to be better compared to in vitro results achieved with perfused dentin, and worse compared to in vitro results achieved without perfused dentin. Additionally, it was noted that the impact of the experimental conditions on the performance of different adhesive materials was dependent on the composition of the materials. Least adaptation was found for the perfused specimens in most groups, and least gap formation for the non-perfused in vitro specimens. A material dependent influence of experimental conditions on the study influenced the results. In vitro adaptation to perfused dentin seems to be undervalued compared to the clinical situation in certain circumstances. [ABSTRACT FROM AUTHOR]

This in vitro study evaluated and compared the efficacy of three in-office bleaching systems and investigated their effect on enamel microhardness. Three groups of 12 teeth (third molars) each were bleached as follows: Group A: Opalescence Xtra Boost (38% HP), Group B: Easywhite Ready (30% HP) with plasma unit and Group C: Zoom2 system (25% HP with the Zoom2 unit). The teeth were stained with tea for 24 hours, followed by the appropriate bleaching procedure. Each bleaching cycle was conducted for 15 minutes. The bleaching procedure was repeated until a shade change of six tabs (VITA shade guide) was obtained. The shade of the teeth was evaluated before, immediately after bleaching and one month later, both visually and digitally. Additionally, the "change of shade tabs per minute" was calculated. For the digital evaluation, the photos were taken under the same circumstances and the L*a*b* values were calculated using Photoshop. Five additional enamel samples for each group were prepared, and Knoop microhardness was evaluated before and after 15 minutes of bleaching. According to the visual shade evaluation, the treatment cycles required to reach the defined level of bleaching were: 1.58 for Group A (23.7 minutes), 1.02 for Group B (16.2 minutes) and 1.25 for Group C (18.7 minutes). Immediately after bleaching, a significant difference was found between Groups A and B (p = 0.0094). However, one month after the bleaching procedure, no significant difference could be observed among the three groups. According to the digital evaluation, no significant differences were found among the three bleaching systems for each of the L*a*b* values and the three times tested (p > 0.05). No significant difference (p = 0.055) was noticed among the three groups regarding microhardness after bleaching.

Contamination of etched enamel with repair bond agents during repair of dental restorations may interfere with the bonding of composite to enamel. This study examined the bond strength of adhesive filling materials to etched bovine enamel after pre-treatment with the repair systems Monobond S, Silibond and Co-Jet. The materials Tetric Ceram, Dyract and Definite and their corresponding bonding agents (Syntac Single Comp, Prime & Bond NT, Etch and Prime) were tested in combination with the repair systems. One hundred and thirty-five enamel specimens were etched (37% phosphoric acid, 60 seconds) and equally distributed among three groups (A-C). In Group A, the repair materials were applied on etched enamel followed by applying the composite materials without using their respective bonding material. In Group B, the composite materials were placed on etched enamel after applying the repair materials and bonding agents. In control Group C, the composite materials and bonding agents were applied on etched enamel without using the repair systems. In each sub-group, every composite material was applied on 15 specimens. Samples were stored in artificial saliva for 14 days and thermocycled 1,000 times (5 degrees C/55 degrees C). The shear bond strength of the samples were then determined in a universal testing machine (ISO 10477). Applying Monobond or Silibond followed by the use of its respective bonding agents resulted in a bond strength that was not statistically different from the controls for all filling materials (Group C). The three composites that used Monobond and Silibond without applying the corresponding bonding agent resulted in bond strengths that were significantly lower than the controls. Utilizing the Co-Jet-System drastically reduced the bond strength of composites on etched enamel. Contamination of etched enamel with the repairing bonding agents Monobond and Silibond does not interfere with bond strength if the application of Monobond and Silibond is followed by using its corresponding bonding system of the composites tested.