Micro-computed tomographic evaluation of the effects of pre-heating and sonic delivery on the internal void formation of bulk-fill composites

Clinical performance of preheating thermoviscous composite resin for non-carious cervical lesions restoration: A 24-month randomized clinical trial

OBJECTIVES

This 24-month, double-blind, split-mouth randomized clinical trial aimed to compare the retention rates of a preheated thermoviscous composite resin (PHT) compared to a non-heated composite resin (NHT) in non-carious cervical lesions (NCCLs).

METHODS

A total of 120 restorations were restored on NCCLs using a preheated (VisCalor bulk, Voco GmbH) and a non-heated (Admira Fusion, Voco GmbH) composite resins with 60 restorations per group. A universal adhesive in the selective enamel conditioning was applied. In the PHT group, composite was heated at 68 °C for using a bench heater. In the NHT group, no heating was employed. Both restorative materials were dispensed into caps and inserted into the NCCLs. The restorations were evaluated at baseline, 6, 12, 18, and after 24 months of clinical service using the FDI criteria. Statistical analysis was performed with Kaplan-Meier estimation analysis for retention/fracture rate and Chi-square test for the other FDI parameters (α=0.05).

RESULTS

After 24 months 108 restorations were assessed. Seven restorations were lost (two for PHT group and five for NHT group), and the retention rates (95 % confidence interval [CI]) were 96.7 % (81.5-99.9) for PHT group and 90.8 % (81.1-96.0) for NHT group, with no statistical differences between them (p > 0.05). The hazard ratio (95 % CI) was 0.52 (0.27 to 1.01), with no significant difference within groups. In terms of all other FDI parameters that were assessed, all restorations were deemed clinically acceptable.

CONCLUSIONS

Both composites showed high rates of retention rates after 24 months.

CLINICAL SIGNIFICANCE

The clinical performance of the new preheated thermoviscous was found to be as good as the non-heated composite after 24-month of clinical evaluation in non-carious cervical lesions.

REGISTRATION OF CLINICAL TRIALS

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Optimizing fracture resistance of endodontically treated maxillary premolars restored with preheated thermos-viscous composite post-thermocycling, a comparative study. Part I

PURPOSE

This research aimed to investigate fracture resistance of endodontically treated maxillary premolars restored using preheated thermo-viscous and fiber-reinforced bulk fill resin composite, in vitro.

METHODOLOGY

Sixty sound human maxillary premolars were selected and divided randomly into 6 groups of ten teeth each (n = 10). Group 1; is the positive control with sound unprepared teeth (P), Group 2; is the negative control in which Mesio-occluso-distal (MOD) cavities were left unrestored (N), Group 3; includes the teeth restored by incremental packing with conventional nanohybrid composite (ChP), Group 4; includes teeth restored with short fiber reinforced bulk fill composite (EF), Group 5; includes teeth restored with preheated thermo-viscous bulk fill composite (VB), and Group 6; includes teeth restored using packable bulk fill composite (XF) Tested restorative materials were bonded with a universal adhesive in self-etch mode. Teeth were kept in distilled water for 24 h at 37 °C proceeded by thermocycling (5- 55 °C, 1200×). Teeth were then exposed to compressive load till fracture at a crosshead speed of 1 mm/min. One-way ANOVA followed by Tukey post-hoc test was implemented to compare between more than two groups in non-related samples. The significance level was established at α = 0.05 for both tests.

RESULTS

Intact teeth significantly recorded the highest fracture resistance values among all groups. A significant difference was recorded among all the tested groups, with the EF recording the highest values, followed by the VB group then the XF group and ChP that recorded the lowest data. Negative control premolars significantly recorded the lowest fracture.

CONCLUSIONS

After thermocycling, endodontically treated maxillary premolars restored with pre-heated thermos-viscous composite did not exhibit an increase in fracture resistance. Notably, our findings indicate that short fiber-reinforced composite demonstrated significantly higher fracture resistance compared to other types of composites assessed in this study. This suggests the potential superiority of short fiber-reinforced composite in enhancing the overall structural integrity of endodontically treated teeth subjected to occlusal forces.

Dentin adhesion of bulk-fill composites and universal adhesives in class I-cavities with high C-factor

OBJECTIVES

The aim of this study was to compare the dentin adhesion of bulk-fill composites in high C-factor class I-cavities before and after thermocycling to a control group using incremental layering technique.

METHODS

A standardized class I-cavity was prepared into 195 human molars, then different universal adhesives were applied either in self-etch or etch & rinse mode, and the cavity was filled according to each materials application protocol. The material combinations used were a conventional layered composite as control, the respective bulk-fill product, two other bulk-fill composites made by different manufacturers, with one of them being tested using two different polymerization times. Furthermore, one thermoviscous bulk-fill composite and one self-adhesive restorative were examined of which the latter can only be applied in self-etch mode. In each group the dentin adhesion to the cavity bottom was measured using microtensile bond strength test initially (24 h water storage) and after thermocycling. All results were statistically analyzed using STATA 17.0.

RESULTS

The statistical analysis showed significant differences between the control and the experimental groups (p < 0.001). The highest mean bond strength before (14.8 ± 10.7 MPa) and after aging (14.2 ± 11.5 MPa) was measured for the etch & rinse-control group. Among the bulk-fill groups, the etch & rinse technique consistently showed higher bond strengths. Bond strength of groups with shortened polymerization did not exceed 2.1 MPa. The bond strength of the self-adhesive restoration material was low before and after thermocycling (2.7 MPa/ 0.0 MPa). Groups with low bond strength values showed a high number of pre-testing-failures.

CONCLUSIONS

Bulk-fill materials used in high C-factor class I-cavities showed lower bond strength during self-etch application. The same applies for a shortened polymerization regime, which cannot be recommended for high C-factor cavities.

CLINICAL SIGNIFICANCE

Today, a large variety of materials and application techniques can be used when placing an adhesive restoration. Whether new instead of established procedures should be applied in high C-factor cavities has to be critically assessed, as they are a demanding scenario for adhesive restorations.

Assessment of internal porosities for different placement techniques of bulk-fill resin-based composites: a micro-computed tomography study

OBJECTIVES

The aim was to compare the porosity of different bulk-fill resin-based composites (RBCs) placement techniques to the conventional incremental technique using microcomputed tomography (μ-CT).

MATERIAL AND METHODS

Occlusal cavities were prepared on extracted human molars, divided into five groups based on the placement technique (n = 10/group). Techniques examined were Monoblock-two-step (SureFil SDR flow + Ceram.X), Monoblock-two-step (Tetric EvoFlow Bulk-Fill + Tetric EvoCeram Bulk-Fill), Monoblock-one-step (Tetric EvoCeram Bulk-Fill), Monoblock with sonic activation (SonicFill2), and incremental technique (Filtek Z250). μ-CT scanning (SkyScan, Bruker, Belgium) assessed the number, volume of closed pores, and total porosity. Analysis of variance on ranks was used (Student-Newman-Keuls method and Mann-Whitney rank-sum test), to determine the significance of RBC viscosity and the sonication placement technique. The Spearman correlation method assessed the correlation between porosity characteristics (α = 0.05).

RESULTS

The SonicFill2 presented a higher number of closed pores than the other groups (p < 0.05). The overall porosity within the restoration seemed greater in this order: Filtek Z250 > SonicFill2 > Tetric EvoFlow Bulk-Fill + Tetric EvoCeram Bulk-Fill > Tetric EvoCeram Bulk-Fill > SureFil SDR Flow + Ceram.X. Sonication was associated with increased number (p = 0.005) and volume (p = 0.036) of closed pores. A strong correlation was observed between the number and volume of closed pores (R2 = 0.549, p < 001).

CONCLUSIONS

The monoblock technique with sonic activation showed significantly more internal porosity than the other placement techniques. Sonication during application contributed to the higher number and volume of closed pores than the passive bulk-fill application.

CLINICAL RELEVANCE

Using bulk-fill materials enhances efficiency, yet void formation remains an issue, depending on viscosity and active/passive delivery of materials. Clinicians must familiarize themselves with effective placement techniques to reduce void formation and optimizing treatment outcomes.

A laboratory pilot study on voids in flowable bulk-fill composite restorations in bovine Class-II and endodontic access cavities after sonic vibration

This pilot study investigated whether sonic-powered application of a bulk-fill resin-based composite (RBC) in Class-II or endodontic access cavities reduces void formation. The crowns and roots of 60 bovine teeth with Class-II cavities (C) and endodontic access cavities (E) respectively, were assigned to ten groups (C1-C5, E1-E5). Cavities were filled with RBC (SDR flow + , one increment) using different application techniques: no adaptation (C1 + E1), spreading of RBC on the cavity surfaces with a dental explorer tip (C2 + E2), low (C3 + E3) or high frequency (C4 + E4) direct activation by inserting a sonic-powered tip into RBC and high frequency indirect activation with an ultrasonic insertion tip (C5 + E5). The restorations were light-cured and investigated for voids using microtomography. The number of voids and percentage of voids related to the volume were statistically analysed (α < 0.05). While most voids in Class-II restorations were observed in C4 (p ≤ 0.0031), no significant differences were found between the other groups (p > 0.05). The percentage of voids showed no differences in E1-E5 (p > 0.05). C4 showed a significantly higher percentage of voids compared to C2 (p < 0.001). There is no benefit in applying sonic vibration when filling Class-II or endodontic access cavities.

3D-2D microleakage assessment of preheated bulk-fill composite resin applied with different parameters: a micro-CT analysis

This study evaluated microleakage from class II cavities filled with bulk-fill composite preheated to different temperatures, applied at different thicknesses, and with different polymerization modes. A total of 60 mesio-occlusal cavity were drilled into the extracted human third molars at 2 mm and 4 mm thickness. Preheated bulk-fill composite resin (Viscalor; VOCO, Germany) was applied to the cavities at 68 °C and 37 °C after the adhesive resin was applied, and cured using standard and high-power light-curing modes of a VALO light-curing unit. An incrementally applied microhybrid composite was used as the control. The teeth were subjected to 2000 cycles of heating to 55 °C and cooling to 5 °C with a 30-s hold time. Then, they were immersed in a 50% silver nitrate solution for 24 h and scanned with micro-computed tomography. Scanned data were processed using the CTAn software. Two (2D) and three (3D) dimensional analyses of leached silver nitrate were performed. The data's normality was assessed using the Shapiro-Wilk test before comparisons using a three-way analysis of variance. In both 2D and 3D analysis, bulk-fill composite resin preheated to 68 °C and applied at 2 mm thickness showed less microleakage. In the 3D analysis, restorations applied at 37 °C and 4 mm thickness in high-power mode showed significantly higher values (p < 0.001). Preheated bulk-fill composite resin can be applied at 68 °C and effectively cured at both 2 mm and 4 mm thickness.

Various ways of pre-heating a bulk-fill thermoviscous composite in restoration in non-carious cervical lesions: 12-month randomized clinical trial

OBJECTIVE

The objective of the study is to evaluate through a randomized clinical trial the best method to preheat a composite resin, if using a Caps dispenser device associated with Caps Warmer (CD) or with a VisCalor Caps dispenser/warmer (VD) for restorations in non-carious cervical lesions (NCCLs).

MATERIAL AND METHODS

One hundred and twenty restorations were distributed to two groups (n = 60) according to the pre-heating way of thermoviscous bulk-fill composite resin. For the CD group, pre-heating was carried at 68 °C using a heating bench for 3 min. For the VD group, pre-heating was performed at 68 °C using a heating gun for 30 s. After that, pre-heated bulk-fill composites were directly inserted in the NCCLs. The total working time was recorded. The restorations were evaluated after 6 and 12 months of clinical performance according to the FDI criteria. Statistical analysis was performed using the Student's t test for unpaired samples for working time, and the Chi-square test for restoration clinical performance (α = 0.05).

RESULTS

Working time was shorter for VD with a statistically significant difference compared to CD (p = 0.01). Few restorations were lost or fractured after 12 months of clinical evaluation (p > 0.05). The retention rates were 96.7% (CI 95 %: 88.6-99.1%) for CD and 98.3% (CI 95 %: 91.1-99.7%) for VD. The other FDI parameters were considered clinically acceptable.

CONCLUSIONS

The different pre-heating ways did not influence the clinical performance of thermoviscous bulk-fill composite restorations in NCCLs after 12 months.

CLINICAL RELEVANCE

Regardless of the bulk-fill thermoviscous composite resin pre-heating ways, the restorations are clinically acceptable after 12 months.

Effect of preheating on mechanical properties of a resin-based composite containing elastomeric urethane monomer

This study investigated the effect of preheating an elastomeric urethane monomer (Exothane-24) experimental resin composite on its physicochemical properties. Two resin matrices were formulated: (a) 50 wt% Bisphenol-glycidyl methacrylate (Bis-GMA) and 50 wt% triethylene glycol dimethacrylate (TEGDMA); and (b) 20 wt% Exothane-24, 40 wt% Bis-GMA and 40 wt% TEGDMA. A photoinitiator system (0.25 wt% camphorquinone and 0.50 wt% ethyl-4-dimethylamino benzoate) and 65 wt% of the inorganic filler (20 wt% 0.05 μm silica and 80 wt% 0.7 μm BaBSiO₂ glass) were added to both matrices. These formulations were then assigned to four groups: Exothane-24 (E); Exothane-24 plus preheating (EH); no Exothane-24 (NE); and no Exothane-24 plus preheating (NEH). NEH and EH were preheated at 69 °C. The dependent variables were as follows: film thickness (FT); polymerization shrinkage stress (PSS); gap width (GW); maximum rate of polymerization (Rp_max); and degree of conversion (DC). Data were statistically analyzed by two-way ANOVA and Tukey's test (α = 0.05). Preheating reduced FT for both composites. PSS and GW were significantly lower for EH, when compared with E. The DC for EH and NEH and the Rp_max for EH increased significantly. Preheating improved most of the physicochemical properties (FT, PSS, GW, and DC) of the experimental resin composite containing Exothane-24.

Effect of Pre-Heating on the Monomer Elution and Porosity of Conventional and Bulk-Fill Resin-Based Dental Composites

The pre-heating of dental resin-based composites (RBCs) improves adaptability to cavity walls, reducing microleakages. However, the rapid cooling of the pre-heated RBC may change the polymerization kinetics, and thus the final network configuration of the RBC. It is well known that unreacted monomers remaining in the set RBC can leach into the oral cavity. However, it is still not clear how the pre-heating and cooling of RBCs alter monomer elution (ME). Thus, the purpose was to determine the ME from room-temperature and pre-heated RBCs, in addition to determining the closed porosity (CP) volume. Bulk-filled RBCs and layered conventional RBC samples were prepared. The pre-polymerization temperature was set at 24 °C and 55/65 °C. The ME from RBC samples was assessed with high-performance liquid chromatography using standard monomers. CP was measured with micro-computed tomography. ME decreased significantly from bulk fills and increased from layered samples as a result of pre-heating. Pre-heating was unfavorable in terms of CP in most RBCs. Based on the effect size analysis, ME and CP were greatly influenced by both material composition, pre-polymerization temperature, and their interaction. While the pre-heating of high-viscosity bulk-fill RBCs is advantageous from a clinical aspect regarding biocompatibility, it increases CP, which is undesirable from a mechanical point of view.

A Comparison of Microtensile Bond Strength, Film Thickness, and Microhardness of Photo-Polymerized Luting Composites

The aim of this study was to evaluate the effect of CAD/CAM composite thickness on micro-tensile bond strength (µTBS), microhardness (HV), and film thickness (FT) of different luting composites. Composite blocks (6.8 mm × 6.8 mm) were divided into 12 groups according to: CAD/CAM thickness and luting composite. For each group, 21 rods (1 mm × 1 mm) were tested in tension at crosshead speed of 1 mm/min. Fracture modes were categorized as adhesive, mixed, and cohesive. Microhardness (n = 5/group) was assessed using microhardness tester. Film thickness (12-rods/group) was evaluated using a stereomicroscope (×40). Data were analyzed using the two-way ANOVA/Tukey’s HSD test (p = 0.05). Parameters “thickness”, “cement”, and “thickness x cement” showed significant difference on µTBS and HV (p < 0.05). At 2 mm, heated x-tra fil composite showed the highest µTBS (45.0 ± 8.5 MPa), while at 4 mm thickness, Grandio Flow revealed the lowest µTBS (33.3 ± 6.3 MPa). Adhesive, mixed, and cohesive failures were reported. The HV of all composites decreased when photo-polymerized through 4 mm thickness (p < 0.05). Regardless of CAD/CAM thickness, photo-polymerized composites can be successfully used for luting CAD/CAM composite.

Coulometric titration of water content and uptake in CAD/CAM chairside composites

OBJECTIVES

This study aimed to evaluate the water content and uptake of CAD/CAM chairside composites over 60 days using coulometric Karl Fischer (KF) titration.

METHODS

Rectangular plates (10 ×10×1 mm³ of thickness) were cut from the blocks of composites Cerasmart 270 (CS), Katana Avencia (KA), Grandio Blocs (GB), and Lava Ultimate (LU). Specimens were stored in distilled water for up to 60 days at 37 °C, and non-stored specimens were used as a control (n = 5). Specimens were isothermally heated at 200 °C, and the water content was evaporated and transferred to the titration cell throughout a nitrogen gas flow. The KF coulometer determined the percentage of water in each specimen. Data were analyzed by 2-way ANOVA and Tukey`s test (α = 0.05).

RESULTS

The water content of non-stored specimens ranged from 0.29 to 1.66 wt% (6.9-32.9 μg/mm³) for GB and LU, respectively. The water content increased underwater storage (0.82-2.96 wt% after 60 days). The extend of water sorption (11.9-26.1 μg/mm³) among the materials was directly related to their base water content. No additional water content increase was observed after 7 (LU and KA) or 21 (GB and CS) days. Measuring the water content in wt% or μg/mm³ affected the ranking of materials when KA and CS were analyzed.

SIGNIFICANCE

Composites with higher base water content also presented higher water sorption. KF titrationshowed to be a reliable method to measure the water sorption of composites, including their base water content.

Viscosity modulation of resin composites versus hand application on internal adaptation of restorations

OBJECTIVE

To compare the effect of the injection of viscosity modulated resin composites versus hand application without modulation, on the internal adaptation of different material to the gingival wall of class II preparations.

MATERIALS AND METHODS

Class II cavities were created on mesial and distal surfaces of 60 extracted human molars, resulting on 120 tooth preparations (n = 120). The preparations were restored with four resin composites: VIS-VisCalor (Voco); GRA-GrandioSO (Voco); FIL-Filtek One Bulk Fill (3 M/ESPE); and SON-SonicFill (Kerr). Each composite was applied by two different techniques: by hand (H) or assisted (A). For the hand technique, the material was placed into the preparation using a spatula. For the assisted technique, the resin composite was heated up to 65 °C (for VIS, GRA, and FIL) or sonicated (for SON) and injected into the preparation. After the restorative procedures, the teeth were completely demineralized to allow the restoration removal. The total area of the gingival wall and the area occupied by interfacial defects of adaptation (TDA) were measured by optical microscopy and digital software. The percentage of the area occupied by the defects (%TDA) in relation to the total area was calculated. The data were analyzed by two-way ANOVA and Tukey tests.

RESULTS

Significant differences were observed for the application technique (p = 0.0403) and for the materials (p = 0.0184), as well for the interaction between them (p = 0.0452). The mean (standard deviation) of %TDA and results of Tukey test for the interaction were as follows: SON/H - 1.04(0.75)a; VIS/A - 2.01(0.92)a; VIS/H - 3.62(0.99)b; GRA/A - 6.23(3.32)b; FIL/H - 7.45(3.31)bc; GRA/H - 9.21(4.53)c; SON/A - 11.26(4.04)a; FIL/A - 17.89(5.08)d.

CONCLUSION

The injection of heated resin composites improves the adaptation to the walls in relation to the hand technique for VisCalor and GrandioSO but worsens for Filtek One. Sonic vibration increases the number of interfacial defects for SonicFill.

CLINICAL RELEVANCE

The physical modulation of the resin composite viscosity can improve or worsen the material adaptation to the walls of class II restoration. It had a positive impact for VisCalor and GrandioSO but a negative for Filtek One and SonicFill.

Effect of Preheating and Vibration on Microhardness and Microleakage of Microhybrid Resin Composite (In Vitro Study)

BACKGROUND: Preheating and sonic vibration are two methods for the treatment of microhybrid resin composites that may effect on their mechanical and physical properties. AIM: This study was conducted to assess the effect of using preheating and sonic vibration on microhardness and microleakage of microhybrid resin composite METHODS AND MATERIALS: For microhardness test, a total of 30 samples of resin composite discs were prepared. Samples were divided into three groups according to the method of treatment of resin composite, controlled group (T0), preheated group (T1), and sonic vibration group (T2). Surface microhardness values were evaluated at baseline and after thermocycling. For microleakage test, a total of 30 Class-V cavities were prepared on the labial surfaces of extracted human anterior teeth. The cavities were then divided into three groups according to the method of resin composite treatment as mentioned before in the microhardness test. All samples were sectioned; then two-dimensional cross-sectional images from each sample. Each cross-sectional image was analyzed using Image J software to quantify interfacial microleakage at the cavity floor. STATISTICAL ANALYSIS USED: Two-way ANOVA analysis was used to test the effects of thermocycling on three groups of each test. One-way ANOVA was used to compare between three different methods of resin composite treatment. RESULTS: For microhardness at baseline revealed that the highest mean value was recorded for the control group, followed by the sonic vibration group meanwhile, the lowest mean value was recorded for the sonic vibration group, followed by preheated group at microleakage test. CONCLUSION: Preheating and sonic vibration of microhybrid resin composite does not improve its microhardness; however, sonic vibration provides better marginal adaptation than the preheating and the conventional methods.

Pre-Heating Effect on Monomer Elution and Degree of Conversion of Contemporary and Thermoviscous Bulk-Fill Resin-Based Dental Composites

Detection of unreacted monomers from pre-heated resin-based dental composites (RBC) is not a well-investigated topic so far. The objectives were to determine the temperature changes during the application and polymerization, the degree of conversion (DC) and unreacted monomer elution of room temperature (RT), and pre-heated thermoviscous [VisCalor Bulk(VCB)] and high-viscosity full-body contemporary [Filtek One Bulk(FOB)] bulk-fill RBCs. The RBCs' temperatures during the sample preparation were recorded with a K-type thermocouple. The DC at the top and bottom was measured with micro-Raman spectroscopy and the amounts of eluted BisGMA, UDMA, DDMA, and TEGDMA were assessed with High-Performance Liquid Chromatography. The temperatures of the pre-heated RBCs decreased rapidly during the manipulation phase. The temperature rise during photopolymerization reflects the bottom DCs. The differences in DC% between the top and the bottom were significant. RT VCB had a lower DC% compared to FOB. Pre-heating did not influence the DC, except on the bottom surface of FOB where a significant decrease was measured. Pre-heating significantly decreased the elution of BisGMA, UDMA, DDMA in the case of FOB, meanwhile, it had no effect on monomer release from VCB, except TEGDMA, which elution was decreased. In comparison, RBC composition had a stronger influence on DC and monomer elution, than pre-cure temperature.

Assessing Fracture Resistance of Restored Premolars with Novel Composite Materials: An In Vitro Study

During restorative treatment, premolars restored with resin filling materials using the conventional incremental-fill technique take longer restoration time and undermine the integrity of the tooth. The aim of this study was to assess fracture resistance of premolars restored by various types of novel bulk-fill composite resin materials. Forty-eight (n = 48) freshly extracted sound maxillary first premolars were used in this in vitro study. The teeth were divided into six groups, each having 8 specimens. Group A (positive control) was allocated for the intact teeth. For specimens in Groups B to F, a large cavity (Class-II MOD) was prepared with a standardized dimension of cavity (3 mm depth on the pulpal floor, 4 mm at the gingival seat, and 3 mm cavity width). Group B represented prepared teeth without any restoration. Group C, Group D, Group E, and Group F were restored with Tetric EvoCeram^® incremental-fill (conventional), Beautifil bulk-fill, Filtek posterior bulk-fill, and SonicFill 2 bulk-fill restorative materials, respectively. All samples were finished and polished with an enhanced finishing kit and stored in distilled water for a month before the fracture resistance testing. All the samples were exposed to the axial loading (the speed of crosshead was 1 mm/min) in a computer-controlled universal testing machine (LARYEE, China) via a steel bar (6 mm in diameter) and the maximum applied force in Newton was recorded as the fracture resistance. One-way analysis of variance (SPSS 21) was used to compare the fracture resistance within the groups, and Tukey's post hoc test was used to determine the difference between the groups. The lowest value of fracture resistance was recorded for Group B, and the highest value was recorded for Group A followed by the values of Group D, Group C, Group F, and Group E. One-way ANOVA revealed a statistically significant difference between the groups (P < 0.05). Nonsignificant difference was found between the premolars restored by bulk-fill and conventional composites. Among the bulk-fill restored specimens, Beautifil restorative demonstrated significantly higher fracture resistance in comparison with the other two bulk-fill restored specimen groups (SonicFill 2 and Filtek). Bulk-fill composite such as Beautifil could be an alternative option to conventional incremental-fill composite for premolar restoration.

Six-year clinical evaluation of bulk-fill and nanofill resin composite restorations

OBJECTIVES

This study aims to compare the performance of a bulk-fill and a nanofill resin composite in class II restorations after 6 years.

MATERIALS AND METHODS

Fifty patients having at least two class II carious lesions were recruited for the study. One lesion in each patient was randomly assigned to be restored using either the Tetric EvoCeram Bulk Fill (TB) or Filtek Ultimate (FU) resin composites with their respective adhesives. One hundred four restorations were placed by two calibrated operators. Restorations were evaluated at baseline and annually over the course of 6 years by two examiners using modified USPHS criteria. Data were statistically analyzed using the Chi-square and Cochran Q tests (p < 0.05).

RESULTS

Sixty-six restorations in 33 patients were evaluated after 6 years. Only one restoration was lost from FU group at 5 years. At the end of 6 years, marginal discoloration was observed in three (9.1%) TB and eight (36.4%) FU restorations creating a significant difference between the groups (p < 0.05). The FU group showed a significant increase in marginal discoloration at 6 years from the baseline (p < 0.05). Marginal adaptation was rated as Bravo for 9.1% and 24.2% of TB and FU restorations, respectively (p > 0.05). Significant degradation was observed within each group in terms of marginal adaptation (p < 0.05). There were no statistically significant differences between the groups for the other criteria tested (p > 0.05).

CONCLUSIONS

Bulk-fill restorations performed better for marginal discoloration. The remaining clinical performance criteria of bulk-fill and nanofill resin composite restorations were similar after 6 years.

CLINICAL RELEVANCE

Bulk-fill resin might be a better alternative to incrementally placed restorative in terms of marginal discoloration under clinical conditions.