Effects of in-office bleaching agents on polished and unpolished nanofilled resin composite.

BACKGROUND: This study investigates the effects of in-office bleaching agents on the color change and surface roughness of nanofilled resin composite finished by various polishing procedures. METHODS: The authors made 108 specimens from nanofilled resin composite, and the finishing and polishing procedures were performed with either Sof-Lex (3M ESPE) or OneGloss (Shofu). The specimens were then immersed in tea or coffee solution for 1 week, after which in-office bleaching agents were applied (n = 9). After polishing and bleaching, the surface roughness was measured with a surface profilometer. The specimen color parameters were measured with the Commission Internationale de l'Eclairage L∗a∗b∗ system in 3 stages, namely after polishing, after staining, and at the end of the bleaching procedure. The total color changes (ΔEab∗) were calculated, and ΔEab∗ not exceeding 2.7 was considered a clinically acceptable threshold. RESULTS: The highest initial roughness value was observed on surfaces polished with OneGloss. In all groups, the surface roughness increased significantly after bleaching. For the Sof-Lex group specimens stained in both tea and coffee solutions, bleaching agent Opalescence Boost (Ultradent) reduced the color change value to 2.7 or less after bleaching. CONCLUSIONS: In-office bleaching agents increased surface roughness in all groups, especially on unpolished surfaces. However, surface roughness was at an acceptable threshold for the multistep polished group, Sof-Lex, after bleaching. Nanofilled resin composite staining can be partially reduced by in-office bleaching agents but not completely removed. PRACTICAL IMPLICATIONS: To reduce the increase in surface roughness of composite restorations due to bleaching, polishing should be applied before and after bleaching.

Effect of the erbium:yttrium-aluminum-garnet laser or diamond bur cavity preparation on the marginal microleakage of class V cavities restored with different adhesives and composite systems.

The aim of this in vitro study was to compare the microleakage of Er:YAG laser and diamond bur on different bonding systems in class V restorations. Class V cavities were prepared with Er:YAG laser or diamond bur on 80 intact human molars. Teeth were randomly distributed into ten groups and cavities were restored with CeramX duo (DENTSPLY) or Filtek Silorane (3M/ESPE) using different bonding materials (One Coat 7.0 (Coltène), XP Bond (DENTSPLY), Clearfil Protect Bond (Kuraray), AdperSE (3M/ESPE), and Silorane System Adhesive (3M/ESPE). All specimens were subjected to thermocycling and load cycling. After being immersed in silver nitrate dye, the specimens were sectioned. Microleakage was evaluated by stereomicroscope and SEM. Data were statistically analyzed by one-way ANOVA, Kruskal-Wallis, and Mann-Whitney tests. Statistically differences were found between groups (p > 0.05) and cavities prepared with the Er:YAG laser showed higher microleakage than diamond bur. The microleakage of different bonding systems was influenced by the choice of diamond bur or Er:YAG laser for class V composite cavity preparation.

The effects of halogen and light-emitting diode light curing on the depth of cure and surface microhardness of composite resins.

AIM: Light-emitting diode light curing units (LED LCUs) have become more popular than halogen LCUs in routine dental restorative treatment. The aim of the study was to compare the effects of two conventional halogen (Hilux Plus and VIP) and two LED (Elipar FreeLight 2 and Smart Lite) light curing units on the depth of cure and the microhardness of various esthetic restorative materials. MATERIALS AND METHODS: The curing depth and microhardness of a compomer (Dyract Extra), a resin-modified glass ionomer (Vitremer), a packable composite (Sculpt It), an ormocer (Admira), a hybrid composite (Tetric Ceram), two microhybrid composites (Miris and Clearfil Photo Posterior) and, a nanofil composite (Filtek Supreme) were determined using a scraping method and a hardness tester. A total of 320 samples were prepared using the eight different materials (n = 10 samples for each subgroup). The scraping test was based on ISO 4049:2000. Vicker's microhardness testing was carried out using hardness tester (Zwick 3212). Data were analyzed using one-way analysis of variance (ANOVA), Bonferroni and the Kolmogorov-Smirnov tests. RESULTS: Best microhardness results were obtained with the LED light curing units and Tetric EvoCeram and Filtek Supreme achieved the highest hardness values. The nanofil composite, Filtek Supreme, showed the best curing depth results in all the tested light curing systems. CONCLUSIONS: The LEDs were found to be more successful than the halogen units with respect to both curing depth and microhardness properties.

Microleakage of repaired class V silorane and nano-hybrid composite restorations after preparation with erbium:yttrium-aluminum-garnet laser and diamond bur.

The aim of this in vitro study was to compare the microleakage of repaired class V resin composite restorations prepared either by Er:YAG laser or a diamond bur. Ninety-six intact human molar teeth were randomly distributed into eight groups. In the first four groups, class V cavities (3 × 3 × 3 mm) prepared on the buccal and lingual surfaces of the teeth using an erbium:yttrium-aluminum-garnet laser (VersaWave, HOYA ConBio, Japan). Similar class V cavities were prepared in the second four groups using a diamond bur (S-Class, Komet, UK). Teeth in groups 1, 2, and 5, 6 were restored with a nano-ceramic composite (Ceram.X duo, DENTSPLY), whereas a silorane material (Filtek Silorane, 3M ESPE) was used to restore cavities in groups 3, 4, and 7, 8. Two different adhesive systems (XP Bond, DENTSPLY, and Silorane System Adhesive, 3M ESPE) were also used. All specimens were aged for 7 days. New cavities (3 × 3 × 3 mm) were prepared adjacent to the old restorations with Er:YAG laser (groups I-IV) or diamond bur (groups V-VIII). Different repair materials were then applied to the new cavities using the previous two restorative materials and two adhesive systems. All teeth were subjected to thermocycling (5,000 cycles between 5 and 55°C) and axial loadcycling (30 N, 1 Hz, 2,000 cycles). Specimens were immersed in 50% w/w silver nitrate solution. Teeth were sectioned longitudinally in buccolingual direction. Stereomicroscope (Nikon SMZ 800) and SEM (JEOL JSM 5600) were used to evaluate the microleakage that existed at the interface between the old restorations and the repair materials. Data were analyzed statistically with one-way ANOVA and Tukey tests (p < 0.05). Even though no statistically significant differences were found between any of the groups, the cavities repaired with different restoratives showed slight microleakage, especially those prepared by Er:YAG laser (p > 0.05). No microleakage scores were obtained in the groups repaired with Filtek Silorane/Filtek Silorane and Ceram.X/Ceram.X. All the substances tested can be used as repair materials for immediate repair after Er:YAG laser and diamond bur. All substances tested in this study can be used as immediate repair materials after cavity preparations with Er:YAG laser or diamond bur.

Effect of Thermo-mechanical Load Cycling on Microleakage in Class II Ormocer Restorations.

OBJECTIVES: The objective of this in vitro study was to evaluate the marginal sealing ability of an ormocer in comparison with a hybrid composite when using thermocycling and load cycling procedures together in the study design. METHODS: Modified proximal Class II cavities were prepared on the mesial and distal surfaces of twenty-two human premolars. Each tooth was restored with Admira and contralaterally with TPH Spectrum. Half of all of the teeth were subjected to thermo-mechanical load cycling. After dye penetration, longitudinal sections in mesio-distal direction were prepared and examined under a stereomicroscope. Data were analyzed with Mann Whitney U test. RESULTS: The results showed that the thermo-mechanical load cycling caused a statistically significant increase in gingival microleakage when compared with the non-thermocycled and non-loaded restorations for both the materials Admira (P=0.006) and TPH Spectrum (P=0.023). CONCLUSIONS: Simultaneous load cycling and thermocycling are decisive factors in the in vitro assessment of gingival microleakage, which still remains to be a clinical problem even with the ormocer system Admira.

Clinical evaluation of an ormocer, a nanofill composite and a hybrid composite at 2 years.

PURPOSE: To evaluate the 2-year clinical performance of an ormocer, a new nanofill composite and as a control a conventional hybrid composite restorations in small Class I cavities of permanent molars. METHODS: 90 Class I maxillary cavities were prepared in 90 patients. Cavities were restored incrementally in oblique layers with ormocer (Admira), nanofill (Filtek Supreme), or hybrid (Renew) composite material. Restorations were examined using the United States Public Health Service modified Ryge criteria at baseline, after 6 months, 1 year and 2 years. The changes in the parameters during the 2-year period were assessed with Friedman test analysis. Comparison of the baseline scores with those at the recall periods was evaluated by Wilcoxon signed rank test; the level of significance was set at P< 0.05. RESULTS: None of the restorative materials exhibited secondary caries or postoperative sensitivity at the 6-month, 1-year or 2-year recall (P> 0.05). After 2 years, except the one failed Admira restoration, no other criteria was clinically unacceptable.

Two-year clinical evaluation of ormocer and nanofill composite with and without a flowable liner.

PURPOSE: The aim of this clinical follow-up study was to determine the clinical performance of ormocer and a new nanofill composite material, lined or not lined with flowable composites, after 2 years. MATERIALS AND METHODS: Occlusal restorations (n = 108) were placed in 54 patients with two symmetric restorations per patient. In one of the two restorations in each patient, cavities were first lined with the flowable composite material Admira Flow or Filtek Flow after applying the two-step total-etch one-bottle adhesive (Admira Bond) or single bond adhesive (Single Bond). Admira or Filtek Supreme was then applied. Restorations were examined using the USPHS modified Ryge criteria for retention, color matching, cavosurface marginal discoloration, anatomic form, marginal adaptation, surface texture, and secondary caries by two previously calibrated dentists. The overall performance of the restorations was evaluated by Wilcoxon signed ranks test. The chi-square test was used to determine differences in the performance of the restorations in which the flowable composite was applied first. RESULTS: There was no secondary caries or postoperative sensitivity in any of the restorations at the 6-month, 1-year, and 2-year follow-up examinations. After 2 years, only one Admira restoration had failed; all other restorations were available for evaluation. There were no statistically significant differences among the materials regardless of the prior use of flowable material (p > 0.05). There was no statistically significant difference between the restorations with and without the prior application of flowable materials (p > 0.05). CONCLUSION: The clinical performance of occlusal restorations using ormocer or nanofill composite did not benefit from the additional use of the flowable composite. Both of the restorative materials exhibited ideal clinical performance.

Effects of dietary acids on surface microhardness of various tooth-colored restoratives.

The aim of this in vitro study was to investigate if surface microhardness of Fuji IX GP, Vitremer, Dyract AP, and Prodigy is influenced by conditioning in aqueous solutions of lactic, orthophosphoric, citric, and acetic acids against bidistilled water (which was used as control). The pH values of acids used in this study were representative of dietary acids. All specimens were stored in bidistilled water for one week and then conditioned in the respective test solutions for another week. Citric (p<0.05) and acetic acids reduced, while lactic and orthophosphoric acids (p<0.05) increased the microhardness of both Fuji IX GP and Vitremer. On the other hand, microhardness of both Dyract AP and Prodigy was significantly reduced by all acidic media (p<0.05). The observed differences in the surface microhardness of various tooth-colored restorative materials conditioned in several media varied not only with the pH but also the nature of the acidic solution, and with the composition of the evaluated material.

Effect of operators' skills on increase in cavity volume of restorations.

OBJECTIVE: The purpose of this in vitro study was to evaluate the change in cavity volume after removal of amalgam and resin composite restorations, based on the dental skills of the operators. METHOD AND MATERIALS: A high-speed turbine and diamond burs were used to prepare Class II cavities in 60 acrylic resin mandibular first molar teeth. After the teeth were weighed with precision scales, the cavities were restored with amalgam or posterior resin composite. The restored teeth were then stored in distilled water at room temperature for 48 hours. Three undergraduate students with 2 years' practical experience on patients, and three postgraduate students with an additional 4 years' practical experience in the Department of Operative Dentistry, removed the restorations from the cavities with a high-speed turbine, and the teeth were all weighed again. After cavities were rerestored with the same materials, each restoration was removed once more by the same operator. The weighing procedure was repeated before and after the removal of the restorations. The data were subjected to paired and unpaired t tests. RESULTS: Every time a restoration was removed from a tooth, the cavity preparation became significantly larger, but the postgraduate students caused significantly smaller increases in cavity volume. CONCLUSION: Increases in cavity volume are not based on the nature of t he restorative material; however, the individual experience levelsand dental skills of the operators lead to significant differences in the cavity volume increase.

Abrasive effect of brushing on ormocers following acid conditioning.

The purpose of this study was to evaluate the effect of toothbrushing on the surface roughness and microhardness of Admira and Definite following acid conditioning. Half of the samples were either used as controls or brushed for 10 minutes using an electric toothbrush with slurry. The remaining specimens were stored in orthophosphoric acid with a pH of 1.9 for 24 hours and then half were brushed. The surface roughness of Admira and Definite was not significantly affected by storage under acidic conditions. However, the specimens of both materials in the control groups and the ones tested after acidic storage were found to be significantly smoother than the specimens subjected to toothbrushing alone and brushing following acid conditioning. For both materials, significantly higher values of microhardness were obtained after toothbrushing following acid conditioning than toothbrushing alone. Therefore, brushing following acid conditioning significantly affects the surfaces of the ormocers.