Tetric N-Ceram Bulk Fill Research Articles

The Impact of Modeling Liquids on Surface Roughness and Color Properties of Bulkfill Resin Composites After Simulated Tooth Brushing: An in Vitro Study. Part I.

To evaluate the effect of different modeling agents on color changes, surface roughness, and translucency parameters over time in Bulkfill resin composites. Sixty specimens were prepared using three Bulkfill resin composites (Tetric N-Ceram Bulkfill, Filtek One Bulkfill and Opus Bulkfill) and three modeling agents (Wetting Resin, Optibond FL and Ambar APS). All specimens were subjected to a simulated tooth-brushing (Baseline, 50.000 cycles, 100.000 cycles), and surface roughness was measured at each interval. Surface topography was evaluated. The translucency parameter and color changes were assessed after 24-h, 7-, 14- and 30-day immersion in water, wine, and coffee. Data was analyzed using ANOVA and Bonferroni test. All specimens increased roughness after simulated tooth-brushing (p < 0.05). Wetting Resin decreased roughness on Tetric N-Ceram Bulkfill (p < 0.05). The translucency parameter remained unaltered for all groups. All groups changed color after 30-days of immersion in wine and coffee (p < 0.05). Ambar APS and Wetting Resin on Tetric N-Ceram Bulkfill showed higher color changes when immersed in coffee (p < 0.05). The use of modeling agents does not jeopardize translucency properties but may affect surface roughness and color properties of Bulkfill resin composites depending on their composition. The findings of this study suggest that surface roughness and color properties are affected by the differences in the composition between modeling agents and Bulkfill resins composites.

The 24 months clinical evaluation of class II bulk fill composite restorations

Background: Resin Composite materials are widely used in daily clinical dentistry because of their moderate cost compared with ceramics, easy placement, adequate esthetics, ability to bond with enamel and dentine, and physico-chemical properties. Bulkfill composite materials were introduced to reduce chairside time. These materials have properties such as optimal bond strength, decreased polymerization shrinkage, and reduced cuspal deflection. This in-vivo study compared the clinical performance of three different class II resin composite restorations. Methods: Seventy-one patients (41 females and 30 males) aged 20–43 years with at least three approximal caries were included in the present study. Two hundred twenty-three teeth with approximal caries were restored with two bulk-fill composites (Tetric-N Ceram Bulk fill [TEC], Filtek Bulk Fill [FB]) and a posterior resin composite (Gradia Direct Posterior [GDP]). Two experienced dentists clinically evaluated the restorations with a 5x magnification loupe using the modified United States Public Health Service (USPHS) criteria at baseline and at 24 months. Results: The chi-square test was performed for statistical analysis. The cumulative retention rate for all restorations at 24 months was 90.5%. Retention loss was observed for three TEC (6.1%), four FB (8.2), and seven GDP (14%) restorations. There was no statistically significant difference among the three resin composite restoration groups in color match, marginal adaptation, surface roughness, marginal discoloration, anatomical form, and secondary caries criteria (P&gt;0.05). Conclusion: Bulk-fill composite restorations in class II slot cavities have the same clinical results as traditional posterior composite restorations.

Effect of a 3-second Off-label Exposure on the Depth of Cure of Eight Resin-based Composites.

This study evaluated the depth of cure (DoC) of eight resin-based composites (RBCs) photocured using one multipeak light-curing unit (LCU) on the standard output setting for the manufacturer's RBC recommended exposure time and at a higher irradiance for 3 seconds. Three conventional RBCs: Tetric EvoCeram (Evo), Tetric N-Ceram (Cer), Tetric Prime (Pri); and five bulk-fill: Tetric N-Ceram Bulk Fill (CerBF), Opus Bulk Fill APS (OpusBF), Opus Bulk Fill Flow APS (OpusF), Tetric PowerFill (PFill) and Tetric PowerFlow (PFlow) were examined. Only PFill and PFlow are formulated to be photocured in 3 seconds. The RBCs were packed into a metal mold and photocured using a Bluephase PowerCure LCU for the RBC manufacturer's recommended exposure time on the standard mode and using the 3-second high irradiance mode. After photocuring, the specimens were immersed in a solvent for 1 hour. The length of the remaining RBC was measured and divided by 2. Data were analyzed using two-way analysis of variance (ANOVA) followed by the Tukey post hoc multiple comparison test (α=0.05). There was no significant difference in the DoC values for PFill and PFlow when photocured using the 3-second high irradiance protocol compared to the lower irradiance standard mode protocol. All other RBCs had significantly lower DoC values (p<0.001) when photocured off-label using the 3-second high irradiance mode. Of the eight RBCs tested, only PFill and PFlow achieved the same DoC when the high irradiance 3-second curing method was used compared to when their longer lower irradiance protocol was used.

Effect of Polywave and Monowave Light Curing Units on the Microtensile Bond Strength and Failure Types of Different Bulk-Fill Resin Composites: An in vitro Study.

This study aimed to evaluate the effects of polywave and monowave light-emitting diode curing units on the microtensile bond strength and failure types of three bulk-fill resin composites. This in vitro experimental study was performed on 180 microbars obtained from human third molars and were distributed into 12 groups according to the type of bulk-fill resin composite and the light-curing unit. Third molars were restored using Filtek One Bulk Fill Restorative, Tetric® N-Ceram Bulk Fill, and Opus Bulk Fill resin composites was light-cured with Elipar Deep Cure L and Valo in three modes: standard, high power, and extra power. Subsequently, microtensile analysis was carried out with a universal testing machine and the type of failure with an optical stereomicroscope. For statistical analysis, the Kruskal-Wallis H-test was used, with the Bonferroni post hoc test and Fisher's exact test, considering a significance of p<0.05. There were significant differences in the microtensile bond strength between the Filtek One Bulk Fill restorative and Opus Bulk-Fill (p = 0.042) when light was cured with the polywave unit at standard power. On the other hand, the Filtek One Bulk Fill Restorative and Opus Bulk Fill resins showed significant differences in microtensile bond strength when light was cured with the monowave unit compared with the polywave unit (p<0.05). The presence of alternative photoinitiator systems that are more reactive than camphorquinone produced higher microtensile bond strength in Tetric N-Ceram Bulk Fill and Opus Bulk Fill resins when light-cured with a high and standard polywave unit, respectively, compared to Filtek One Bulk Fill resins. Finally, Tetric N-Ceram Bulk Fill and Opus Bulk Fill resins had the highest percentage of mixed failures, while Filtek One Bulk Fill resin had adhesive failures, which was related to its lower microtensile bond strength.

Polymerization efficiency of different bulk-fill resin composites cured by monowave and polywave light-curing units: a comparative study.

The objective was to evaluate the polymerization efficiency of different bulk-fill resin-based composites cured by monowave and polywave light-curing units, by assessment of the degree of conversion and Vickers microhardness at different depths. Two commercially available bulk-fill resin-based composites were used: Filtek One Bulk Fill Restorative (3M ESPE) and Tetric N-Ceram Bulk Fill (Ivoclar Vivadent). The light-curing units utilized were two LED light-curing units: a monowave LED light-curing unit (BlueLEX LD-105, Monitex) and a polywave LED light-curing unit (Twin Wave GT-2000, Monitex). For each test, 20 cylindrical specimens (4 mm diameter, 4 mm thickness) were prepared from each bulk-fill resin-based composite using a split Teflon mold. Ten specimens were light-cured by the monowave light-curing unit and the other ten were light-cured by the polywave light-curing unit according to the manufacturer's recommendations. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) was used to assess the degree of conversion, and a Vickers microhardness tester was used to assess Vickers microhardness. Statistical analysis was performed using three-way ANOVA and Tukey post-hoc tests (P < .05). The degree of conversion and Vickers microhardness in bulk-fill resin-based composites containing only camphorquinone as photoinitiator were similar when cured with either monowave or polywave light-curing units. However, bulk-fill resin-based composites containing a combination of photoinitiators exhibited significantly higher degree of conversion and Vickers microhardness when cured with a polywave light-curing unit. Although all groups showed statistically significant differences between the top and bottom surfaces regarding degree of conversion and Vickers microhardness, all of them showed bottom/top ratios > 80% regarding degree of conversion and Vickers microhardness. The polywave light-curing unit enhanced the polymerization efficiency of bulk-fill resin-based composites especially when the latter contained a combination of photoinitiators, but does not prevent the use of a monowave light-curing unit.

Two-year clinical performance of dual- and light-cure bulk-fill resin composites in Class ӀӀ restorations: a randomized clinical trial

ObjectiveThis study aimed to compare the clinical performance of dual- and light-cure bulk-fill resin composites (BFRCs) in Class ӀӀ restorations after 2 years.Materials and methodsA double-blinded, prospective, randomized clinical trial (RCT) was conducted following the CONSORT (Consolidated Standard of Reporting Trials) guidelines. Forty patients were enrolled in the study. Each patient received three compound Class ӀӀ restorations. One dual-cure (Fill-Up; Coltene Waledent AG) and two light-cure (QuiXfil; Dentsply, and Tetric N-Ceram Bulk Fill; Ivoclar Vivadent) BFRCs were used for 120 Class ӀӀ restorations. A universal adhesive (ONE COAT 7 UNIVERSAL; Coltene Waledent AG) was used with all restorations. Restorations were clinically evaluated after 1 week (baseline), 6 months, 12 months, 18 months, and finally after 24 months using the FDI World Dental Federation (FDI) criteria. The Kruskal–Wallis test was used for comparison between BFRCs groups at baseline and at each recall period, and the Wilcoxon signed-rank test was used for comparing different follow-up times of each BFRC to baseline. The level of significance was set at p < 0.05.ResultsAll BFRCs restorations showed only minor changes and revealed no statistically significant differences between their clinical performance for all evaluated parameters at all recall periods; also, there was no statistically significant difference between all recall periods and baseline for all evaluated parameters.ConclusionThe two-year clinical performance of dual-cure BFRC was comparable to light-cure BFRCs in Class ӀӀ restorations.Clinical relevanceDual- and light-cure BFRCs showed excellent clinical performance in Class ӀӀ restorations after a 2-year clinical follow-up.

Evaluation of fracture resistance of maxillary premolars of different geometrical cavities restored with different composite resins incorporated with chitosan nanoparticles.

Composites with 0.2% chitosan nanoparticles (CSN) are used recently; however, this combination needs to be studied in different cavity designs. The aim of the study was to compare the fracture resistance of maxillary premolars with different cavity geometries restored with different types of composite resins incorporated with 0.2% CSN. About 130 extracted human single-rooted maxillary premolars were embedded in acrylic molds 2 mm below cementoenamel junction, divided into five groups for cavity preparations of standardized dimensions. Group 1: (control) intact teeth (n = 10), Group 2: Class I cavities (n = 40), Group 3: Class II mesio-occlusal (MO) (n = 40), Group 4: Class II mesio-occluso-distal (MOD) (n = 40). Groups 2, 3, and 4 were subdivided into four subgroups for composite restoration; A: Neo spectra ST-Universal (NST); B: Tetric N-Ceram Bulk-fill (TNC); C: NST + CSN; and D: TNC + CSN and tested for fracture resistance using universal testing machine. One-way analysis of variance and post hoc Tukey's tests were used for data analysis (P ≤ 0.05). In all groups, the highest fracture resistance was found in MOD cavities, followed by MO and least in Class I cavities. Subgroup D (TNC with CSN) showed the highest fracture resistance in all groups (P ≤ 0.05). Tetric N-Ceramic bulk fill with 0.25% CSN showed high fracture resistance in cavities with different geometries.

Influence of compressive forces and aging through thermocycling on the strength of mono incremental dental composite resins

Understanding dental composite resins' physical and mechanical properties is vital for advancing dental materials science, enhancing durability, and improving patient care. The present study aims to quantitatively investigate the impact of compressive forces and thermocycling aging on the strength of mono incremental dental composite resins, focusing on three materials: 3M Filtek One Bulk Fill, Opus Bulk Fill APS A2 from FGM, and Tetric N-Ceram Bulk Fill VIA from Ivoclar Vivadent. Using a mixed quasi-experimental approach, 84 samples were divided into a control group and an experimental group, comprising 14 samples of each material. The samples underwent a thermocycling process involving temperature cycles between 5°C, 37°C, and 55°C, totaling 10,800 cycles, simulating one year of aging. Subsequently, compressive strength tests were conducted using a universal press to identify the fracture point of the material and calculate its strength. Our results reveal differences in the material before and after thermocycling; however, these differences were not statistically significant concerning strength. Thus, it is concluded that one year of thermocycling aging does not induce substantial changes in the resin that would compromise its strength. Future research should consider extended thermocycling tests spanning multiple years to pinpoint the potential onset of issues affecting material strength durability. Keywords: compressive strength, dental composite resins, thermocycling, aging, mono incremental.

5-year clinical performance of posterior bulk-filled resin composite restorations: A double-blind randomized controlled trial

ObjectivesThe aim of this double-blind, and randomized controlled clinical trial was to evaluate the 5-year clinical performance of posterior resin composite restorations placed with the incremental filling technique [IF] or the bulk-fill technique [BF]. Two different adhesive systems were used: etch-&-rinse (ER) or self-etch (SE). MethodsPosterior dental teeth of 72 participants (n = 236), with a cavity depth of at least 3 mm, were randomly divided into four groups. Restorations were applied with either Tetric N-Bond or Tetric N-Bond SE. The composite resin Tetric N-Ceram Bulk-Fill was placed either with IF or BF. Restorations were evaluated using FDI criteria at baseline and after 1, 2, 3, 4, and 5 years. Statistical analysis was performed using the Wilcoxon Signed rank test (a=0.05). ResultsTwo hundred and four restorations were evaluated after 5 years. Eleven restorations were considered 'failed', ten due to fracture (4 IF and 6 BF) and one due to secondary caries (IF). The annual failure rate was 1.2% for BF and 1% for IF (p = 0.35). When comparing BF and IF, no significant differences were found for any of the parameters evaluated (p > 0.05). Regarding the adhesive systems, 44 and 51 restorations showed minor problems in terms of marginal adaptation and staining, with significantly more marginal discoloration when the self-etch adhesive was used (p = 0.002). SignificanceThe bulk-fill restorative technique showed good clinical behavior compared to the incremental filling technique, especially when using an etch-&-rinse adhesive, after 5 years of clinical evaluation.

Cuspal Deflection and Marginal Integrity of Class II Cavities Restored with Bulk-fill Resin Composites

Objective: This laboratory study aims to assess the cuspal deflection, adaptation, and marginal sealing of premolars restored with bulk-fill resin composites. Methods: Fourty-four premolars received class II preparations (distal and mesial boxes located 1 mm above and 1 mm below the cementoenamel junction, respectively). The teeth were distributed into four groups according to the resin composite used for restoration (n=11): G1 (control): Filtek Z250 XT; G2: Filtek Bulk-Fill; G3: Tetric N-Ceram Bulk-Fill; G4: Aura Bulk-Fill. A digital micrometer was used to measure the cuspal deflection before and after the restorative procedures. Replicas in epoxy resin of the restored teeth were achieved before and after thermal cycles. The cervical margins were observed by SEM at 200x magnification to obtain the percentage of continuous margins (%CM). After thermal cycles, the samples were immersed in a silver nitrate solution, and the microleakage was analyzed in the cervical margins. Results: ANOVA showed no significant differences in the cuspal deflection and %CM among the resin composites. Student’s t-test showed a significant decrease in the %CM after thermal cycles for all resin composites at the cervical margin in dentin. There was higher microleakage at the dentin margin for all the resin composites. Conclusion: Bulk-fill resin composites had comparable behavior to a conventional composite in regard to the cuspal deflection, adaptation, and marginal sealing parameters.

Cuspal Deflection and Marginal Integrity of Class II Cavities Restored with Bulk-fill Resin Composites

Objective: This laboratory study aims to assess the cuspal deflection, adaptation, and marginal sealing of premolars restored with bulk-fill resin composites. Methods: Fourty-four premolars received class II preparations (distal and mesial boxes located 1 mm above and 1 mm below the cementoenamel junction, respectively). The teeth were distributed into four groups according to the resin composite used for restoration (n=11): G1 (control): Filtek Z250 XT; G2: Filtek Bulk-Fill; G3: Tetric N-Ceram Bulk-Fill; G4: Aura Bulk-Fill. A digital micrometer was used to measure the cuspal deflection before and after the restorative procedures. Replicas in epoxy resin of the restored teeth were achieved before and after thermal cycles. The cervical margins were observed by SEM at 200x magnification to obtain the percentage of continuous margins (%CM). After thermal cycles, the samples were immersed in a silver nitrate solution, and the microleakage was analyzed in the cervical margins. Results: ANOVA showed no significant differences in the cuspal deflection and %CM among the resin composites. Student’s t-test showed a significant decrease in the %CM after thermal cycles for all resin composites at the cervical margin in dentin. There was higher microleakage at the dentin margin for all the resin composites. Conclusion: Bulk-fill resin composites had comparable behavior to conventional composites in regard to the cuspal deflection, adaptation, and marginal sealing parameters.

Evaluation of the Microhardness of Different Types of Bulk Fill Resins

The constant search for the ideal restorative material causes the new formulations to aim for an increase of 4 to 5 mm, getting an improvement of its mechanical properties, for example, the organic and inorganic matrix of other materials. With this, the objective of the present study was to evaluate the microhardness of different brands of bulk fill resin. In order to perform the research, 30 specimens were prepared, with group 1 with 10 specimens of the conventional composite resin Opallis (FGM). Group 2 with 10 specimens of Oppus Bulk Fill composite resin (FGM). And group 3 with 10 specimens of the Tetric N-Ceram Bulk fill resin (Ivoclar Vivadent), all made from a preset silicon matrix. Each group was photopolymerized on the upper surface at the time indicated by the manufacturer, stored in an oven with distilled water under 37 ° C for 24 hours. After this period, they were measured with a digital caliper and submitted to the Vickers microhardness test at 5 random points on the upper surface. The values recorded by the microdurometer were taken to the statistical analysis using ANOVA test with Tukey post-test, in which it showed a statistical difference between Bulk fill Tetric N-Ceram (Ivoclar Vivadent) and Opallis (FGM) with p value&lt;0.001, and a statistical difference between Bulk Fill Tetric N-Ceram (Ivoclar Vivadent) and Opus Bulk Fill (FGM) with a p value of 0.001. There was no difference between Opallis and Opus Bulk fill (FGM). It was concluded that Bulk Fill Tetric N- Ceram resin (Ivoclar Vivadent) obtained a lower microhardness when compared to Opallis (FGM) and Opus Bulk Fill (FGM) resins.

A Laboratory Study of the Effect of pH on Solubility of Bulk-Fill and Conventional Composites

Aim: Factors such as the low pH of acidic foods and beverages can affect long-term clinical success of restorative materials in the oral cavity. The aim of this study was to compare the solubility of Bulk-fill and Conventional Nano-Hybrid Resin Based Composites (RBCs) in different solutions. Material and Methods: A total of 60 cylindrical specimens were prepared from two RBCs (Tetric N-Ceram, Tetric N-Ceram Bulk-fill) and their constant weight was measured. The specimens were divided into six groups ( N = 10) in accordance with RBC type and pH solution (solution 1, 2, 3 with pH = 2.5, 5, 7, respectively), and were immersed in desired solutions for 30 days. Then they were weighed again and solubility levels of the specimens were calculated according to ISO 4049. Data were analysed by two-way ANOVA. The test power was considered at 80%. Results: The type of RBC had no significant effect on solubility; while the effect of PH was significant. Solution 1 caused significantly the highest solubility. No statistically significant differences were found among other groups. Conclusions: Considering the limitations of the laboratory investigations, it was concluded that solubility rate of Bulk-fill and Conventional RBCs was higher in solutions with lower pH. There was no difference among the RBCs. However, the solubility rates of all groups are within the clinically normal range.

Effect of Acidic Beverages on the Hardness, Elastic Modulus and Wear Resistance of Giomer and Nongiomer Bulk-fill Materials.

The aim of this study was to evaluate and compare the effect of acidic beverages on the hardness, elastic modulus, and wear resistance of four different resin-based restorative materials. A total of 128 specimens (10 mm diameter, 4 mm thickness) were prepared from a conventional resin composite (Filtek Z250 [Z250]), a giomer bulk-fill (Beautifil Bulk Restorative [BBR]) and two nongiomer bulk-fill materials (Tetric N-Ceram Bulk Fill [TNC] and SonicFill 2 [SF2]). Each material group was divided into four subgroups (n=8) according to the storage media: artificial saliva (control), orange juice, regular Coke, and sports drink. The experimental specimens were immersed in the solutions for 30 minutes, five times a day for 5 days and kept in artificial saliva for an hour between the immersion periods. Control specimens were stored in artificial saliva for 5 days. The nanoindentation test with a Berkovich diamond tip was used to determine the hardness and elastic modulus before and after the 5-day storage periods. Following the nanoindentation tests, the specimens were subjected to a chewing simulator for 120,000 cycles. The specimens were then scanned with a three-dimensional scanner. The wear resistance was analyzed by measuring the volume and height loss. Specimens were observed by environmental scanning electron microscopy. The statistical analyses were performed by analysis of variance, Tukey HDS test, and paired samples t-test (α=0.05). Z250 showed significantly higher elastic modulus in all groups (p<0.05). After erosive cycles, the greatest decrease in hardness and elastic modulus was observed for BBR. TNC showed higher wear resistance than the other resin-based materials (p<0.05). The BBR specimens immersed in acidic solutions showed higher wear rates than the artificial saliva group (p<0.05). Conventional resin composite showed higher hardness and elastic modulus than bulk-fill materials when exposed to acidic beverages but comparable or lower wear resistance. Degradation due to acidic beverages most affected the mechanical properties of giomer bulk-fill.

Thickness-Dependent Light Transmittance and Temperature Rise in Dual-Cure Bioactive and Light-Cure Bulk-Fill Composite Resins.

This study aimed to assess the light transmittance (T) and temperature increase through different increments of dual-cure bioactive bulk-fill restorative material (ACTIVA), light-cure bulk-fill, and conventional composite resin materials. Cylindrical specimens with a diameter of 8 mm and heights of 1, 2, 3, and 4 mm of ACTIVA, Tetric-N-Ceram bulk-fill (TBF), Filtek One bulk-fill (FBF), and Filtek Z250 (FZ) (n = 6 per group, 96 in total) were light-cured with a visible blue low-intensity light-emitting diode (LED) (650-800 mW/cm2 irradiance). T, and the temperature increase, were measured using an optical power meter and a digital thermometer during curing. The T mean values ranged between 0.012 and 0.239 (76.02 to 98.81% light attenuation), while the temperature rise mean values ranged between 9.02 and 20.80 °C. The parameters, including material type (partial eta squared (ηp2) = 0.284, p < 0.0001), thickness (ηp2 = 0.284, p < 0.0001), and their interaction (ηp2 = 0.185, p = 0.047), significantly affected the T values, whereas only the material type (ηp2 = 0.352, p = 0.047) affected the temperature rise values. The T and temperature rise mean values were highest in ACTIVA increments of 1-mm increments, in particular, showing the highest T mean values, followed by similar increments of TBF. A significantly higher T was found in 1-mm increments compared to thicker increments for all materials (p < 0.0001), and a significant positive correlation existed between T and temperature rise values (r = 0.348, p = 0.001). These findings show that the bioactive material ACTIVA and TBF allow for better T than the other materials, with ACTIVA recording a higher temperature rise. However, the large light attenuation observed for all materials, irrespective of thickness, suggests that curing in more than one location with a low-intensity LED is necessary to optimize the curing process. Furthermore, incremental filling of bulk-fill materials using a low intensity LED could be beneficial.

Performance of bulk-fill versus conventional nanocomposite resin restorations supporting the occlusal rests of removable partial dentures: An in vitro investigation

Statement of problemPlacing removable partial denture (RPD) rests on composite resin restorations has long been a debatable issue. Despite developments in composite resins such as nanotechnology and bulk-filling techniques, studies investigating the performance of composite resin restorations when used to support occlusal rests remain scarce. PurposeThe purpose of this in vitro study was to investigate the performance of bulk-fill versus incremental (conventional) nanocomposite resin restorations when they are used to support RPD rests under functional loading. Material and methodsThirty-five caries-free intact maxillary molars of similar coronal size were collected and divided into 5 equal groups (n=7): Enamel (Control) group: rest seats prepared entirely in enamel; Class I Incremental group: Class I cavities restored with incrementally placed nanohybrid resin composite resin (Tetric N-Ceram); Class II Incremental group: Mesio-occlusal (MO) Class II cavities restored with Tetric N-Ceram; Class I Bulk-fill group: Class I cavities restored with high-viscosity bulk-fill hybrid resin composite (Tetric N-Ceram Bulk-Fill); and Class II Bulk-fill group: MO Class II cavities restored with Tetric N-Ceram Bulk-Fill. Occlusal rest seats were prepared mesially in all groups, and clasp assemblies were fabricated and cast in cobalt chromium alloy. Specimens with their clasp assemblies were subjected to thermomechanical cycling using a mechanical cycling machine (250000 masticatory cycles) and 5000 thermal cycles (5 °C to 50 °C). Surface roughness (Ra) was measured with a contact profilometer before and after cycling. Fracture analysis was done using stereomicroscopy, and margin analysis was done with a scanning electron microscope (SEM) before and after cycling. Statistical analysis of Ra was conducted using ANOVA followed by the Scheffé test for between-group comparison and paired t test for within-group comparison. The Fisher exact probability test was used for fracture analysis. The Mann–Whitney test was used for between-group comparison and Wilcoxon signed rank test for within-group comparison for the SEM images (α=.05). ResultsMean Ra increased significantly after cycling in all groups. Significant differences in Ra were found between enamel and all 4 resin groups (P<.001), with no significant differences between incremental and bulk-fill resin groups for both Class I and II specimens (P>.05). No significant differences were found between the 2 resin groups with regard to fracture and margin analysis (P>.05). ConclusionsThe surface roughness of enamel was significantly lower than that of both incremental and bulk-fill nanocomposite resins before and after functional loading. Incremental and bulk-fill nanocomposite resins showed comparable performance in terms of surface roughness, fracture behavior, and marginal adaptation.

A comparative evaluation of preheat treatment, postcure heat treatment, and combined heat treatment on degree of conversion of a bulk-fill composite: An in vitro study.

The aim of this study was to evaluate the effect on the degree of conversion of Tetric N-Ceram Bulk Fill Composite subjected to preheat treatment, postcure heat treatment, and combined heat treatment. A total of 90 samples were prepared from Tetric N-Ceram Bulk Fill using customized stainless steel molds and divided into six groups of 15 samples each based on the heat treatment. Group I (control group): no heat treatment, Group II: preheat treatment at 60°C, Group III: postcure heat treatment at 100°C, Group IV: postcure heat treatment at 200°C, Group V: combined preheat treatment at 60°C and postcure heat treatment at 100°C, and Group VI: combined preheat treatment at 60°C and postcure heat treatment at 200°C. The degree of conversion was analyzed using Raman spectrometer. Data were analyzed using analysis of variance followed by the Scheffé test using Statistical Package for the Social Sciences 20.0 version. The order of values of degree of conversion from maximum to minimum for the groups are as follows: Group VI (98.77 ± 0.52) > Group V (97.11 ± 0.78) > Group IV (95.00 ± 0.86) > Group III (93.00 ± 1.22) > Group II (86.88 ± 1.36) > Group I (76.55 ± 1.42). The statistical analysis revealed a statistically significant difference between the groups (P < 0.05). Combined heat treatment samples showed better values of degree of conversion.

Fracture Load of Molars Restored with Bulk-fill, Flowable Bulk-fill, and Conventional Resin Composite After Simulated Chewing.

This study aimed to compare the fracture toughness of molars with wide mesio-occlusal-distal (MOD) cavities restored with regular and flowable bulk-fill resin composite and a conventional resin composite after 250,000 mechanical cycles of chewing simulation. Thirty-two extracted mandibular third molars were selected and class II MOD cavities involving 2/3 of the intercuspal width and 4 mm depth were prepared. Teeth were divided into four groups based on resin composite type and insertion technique (n=8): (1) CT, unprepared teeth (control); (2) CV, conventional resin composite (Tetric N-Ceram, Ivoclar Vivadent) with incremental technique; (3) R-BF, regular bulk-fill resin composite (Tetric N-Ceram Bulk Fill, Ivoclar Vivadent) with a single increment; and (4) F-BF, flowable bulk-fill resin composite (Tetric N-Flow Bulk Fill, Ivoclar Vivadent) with a single increment, except for a 1-mm-thick layer at the occlusal surface, restored with conventional resin composite (Tetric N-Ceram). All specimens were evaluated to detect the presence and propagation of enamel cracks using a LED transilluminator before and after 250,000 mechanical cycles (SD Mechatronic GmbH). After a chewing simulation, they were subjected to a compressive force in a universal testing machine (DL-2000, EMIC) until fracture. The maximum fracture load of the specimens was measured (N) and the fracture patterns were classified based on the fracture site (above or below the cementoenamel junction [CEJ]). Data were statistically analyzed with one-way ANOVA. All specimens survived after 250,000 mechanical cycles, and no statistically significant differences among groups were observed regarding the fracture toughness (p<0.05). The fracture analysis demonstrated that failures below the CEJ were more common in CV (75%), while CT, R-BF, and F-BF showed this type of failure in 38%, 63%, and 63% of the specimens, respectively. The results of the crack analysis showed that the occurrence of new cracks and crack propagation was also higher in CV (33.3%), followed by R-BF, F-BF, and CT (14%, 14%, and 11% of the specimens, respectively). Teeth restored with regular and flowable bulk-fill composites showed similar fracture toughness after the chewing simulation compared to those restored with the conventional resin composite and unprepared teeth. Furthermore, teeth restored with both regular and flowable bulk-fill composites showed a lower incidence of enamel cracks and fractures below the CEJ compared to those restored with the conventional resin composite.

An In-depth Analysis of the Effects of Preheating Three Different Composite Resin Systems at Two Different Temperatures on Their Microhardness

Abstract Background: Composite restorations often have inferior physical properties compared to natural enamel and dentin, leading to early failure. Preheating the traditional composite before its placement and curing seems to enhance all its physical characteristics magically. The objective of the current research was to assess the impact of preheating on the surface microhardness of commonly used composite resin materials, specifically FILTEK P60, FILTEK Z250XT, and Tetric-N-Ceram Bulk fill. Materials and Methods: The resin composite tubes were either left at the ambient room temperature (24°C ± 1°C) or preheated in a commercial preheating device to 50°C and 60°C for 40 min. By inserting uncured preheated composite resin into class II Mseio-Occluso-Distal (MOD) cavities with specifications of 2 ± 0.3 mm axial height, 2 ± 0.3 mm pulpal depth, parallel proximal walls with a 3 ± 0.3 mm buccolingual width, 1.5 ± 0.3 mm gingival width, and an occlusal isthmus width equal to one-third of the intercuspal distance from composite resin tubes, a total of 99 class II MOD cavities on premolars were established. Each specimen’s Vicker’s hardness number (VHN) was determined. The gathered information was examined utilizing a two-way ANOVA and Tukey’s post hoc test with a significance threshold of 0.05. Results: When preheated to the temperatures of 50°C and 60°C, a remarkable rise in the mean Vickers hardness numbers (VHNs) of all the resin composites compared to those maintained at the room temperature (P &lt; 0.05) was seen. The mean VHNs at the room temperature for FILTEK P60, FILTEK Z250XT, and Tetric-N-Ceram were 47.27 ± 9.08, 59.63 ± 1.56, and 75.69 ± 0.80, respectively, with a significant variation between all of them (P &lt; 0.05). The mean VHNs were, respectively, 108.45 ± 2.42, 103.45 ± 1.29, and 113.00 ± 4.35 at 50°C, with a significant variation between them all. At 60°C, the mean VHNs were, respectively, 121.09 ± 1.30, 128.00 ± 0.89, and 135.00 ± 2.04, with a significant variation between all of them (P &lt; 0.05). Conclusion: The surface microhardness of all investigated composite resins was greatly increased by preheating, with Tetric N-Ceram Bulk Fill showing the greatest value at a preheating temperature of 60°C.

Dental restoration operative time and analysis of the internal gap of conventional resins (Incremental Technique) vs. Bulk Fill (Single-Increment Technique): In vitro study.

To determine the operative time and the internal restoration gap in the restoration-tooth interface in the cavity floor using an incremental technique for conventional resins and the single-increment technique for the bulk fill resin. In this in vitro experimental study, the internal gaps of the restoration-tooth interfaces in the cavity floors of two conventional resins and two bulk fill resins were microscopically analyzed, and the restoration times of the single-increment technique and the incremental technique were determined. Bulk fill resins had smaller internal gap (63.31 µm) than conventional resins (333.14 µm). Regarding the restoration time, the single-increment technique obtained the best results in operative time (3.52 minutes), with significant differences relative to the incremental technique. The Tetric N-Ceram bulk fill resin presented better performance than conventional resins relative to the internal gap of the restoration-tooth interface in the cavity floor. In addition, the single-increment technique presented a short clinical restoration time. Key words:Composite, internal gap, restoration technique.