Effect of fiber-reinforced direct restorative materials on the fracture resistance of endodontically treated mandibular molars restored with a conservative endodontic cavity design.

OBJECTIVE: This study aimed to evaluate the fracture strength of teeth restored using fiber-reinforced direct restorative materials after endodontic treatment with a conservative mesio-occlusal access cavity design. MATERIALS AND METHODS: A total of 100 extracted intact mandibular first molars were selected and distributed into a positive control group where teeth left intact and the following four test groups comprised of teeth with conservative mesio-occlusal access cavities that had undergone root canal treatment (n = 20/group): access cavity without restoration (negative control), bulk-fill resin composite with horizontal glass fiber post reinforcement, fiber-reinforced composite with bulk-fill resin and bulk-fill resin composite. Following thermocycling (10,000 cycles), fracture resistance was measured using a universal testing machine. Statistical analyses (one-way analysis of variance and the Tamhane test) were performed, and statistical significance was set at p < 0.05. RESULTS: Groups with minimally invasive access cavities had lower fracture strength than intact teeth, regardless of the restoration material (p < 0.05). Fiber-reinforced composite groups demonstrated higher fracture strength than bulk-fill resin composite alone (p < 0.05). Fracture types varied among groups, with restorable fractures predominant in the fiber-reinforced composite groups. CONCLUSION: This study suggests that using fiber-reinforced composite materials, especially in combination with bulk-fill resin composites, can effectively enhance the fracture strength of endodontically treated teeth with conservative access cavities. However, using only bulk-fill resin composite is not recommended based on the fracture strength results. CLINICAL SIGNIFICANCE: When teeth that undergo endodontic treatment are restored using a conservative access cavity design and fiber-reinforced composite materials, especially in combination with bulk-fill resin composites, the fracture strength of the teeth can be effectively increased.

Comparing the effectiveness of caries arrest by micro-operative treatment to operative treatment: A 2-year randomized controlled clinical trial.

OBJECTIVES: To compare the effectiveness of caries arrest by micro-operative treatment (sealing) to operative treatment (flowable resin composite restoration) through a 2-year randomized controlled clinical trial. MATERIALS AND METHODS: A prospective randomized controlled trial was conducted among 7-9-year-old children. At baseline, 630 subjects were screened and 92 children who had at least one carious lesion classified as ICDAS 3 on the pit and fissure of first permanent molar were included. Then they were randomly assigned to the sealant group (73 lesions) and the flowable resin composite group (76 lesions) to receive the corresponding intervention. Lesions status in each group was evaluated every 6 months up to 24 months. Clinical progression of dental caries and materials retention were the outcomes used for group comparisons at p-value < 0.05. RESULTS: After 24 months, three lesions (4.1%) in the sealant group clinically progressed to dentin caries. No lesion in the flowable composite group was observed a progression. The results of Life-table survival analysis show that the cumulative caries arrest rate had no statistically significant difference between the two groups (p = 0.075). However, the cumulative retention rate was 57.5% in the sealant group and 92.1% in the flowable composite group, with significant differences (p < 0.001). The multilevel mixed model showed the sealant had higher risk of retention failure than the flowable composite (OR = 8.66, p < 0.001), while tooth position did not influence material retention (p = 0.083). In addition, the results of Fisher Exact test show that dentin lesions had more retention failure than enamel lesions in the sealant group (p = 0.026). CONCLUSION: Although sealing microcavitated carious lesions of the first permanent molar achieved lower retention rate than resin composite restoration, both sealing and restoration effectively arrested caries progression for two years. CLINICAL RELEVANCE: To preserving dental structure and delaying or eliminating the need for operative procedures, microcavitated carious lesion can be arrested by sealing. TRIAL REGISTRATION: Registered at http://www.chictr.org.cn ; Feb 15th, 2020; No. ChiCTR2000029862.

Marginal integrity of prototype bioactive glass-doped resin composites in class II cavities.

OBJECTIVES: This in vitro study examined the marginal integrity of experimental composite materials doped with bioactive glass (BG). MATERIALS AND METHODS: Class-II MOD cavities were prepared and restored with one of the following composite materials: a commercial composite material as a reference (Filtek Supreme XTE), an experimental composite doped with BG 45S5 (C-20), and an experimental composite doped with a fluoride-containing BG (F-20). Six experimental groups (n = 8) were used, as each of the three composites was applied with (+) or without (-) a universal adhesive (Adper Scotchbond Multipurpose). All specimens were subjected to thermocycling (10,000 x, 5-55 °C) and then additionally stored in artificial saliva for eight weeks. Scanning electron micrographs of the mesial and the distal box were taken at three time points (initial, after thermocycling, and after eight weeks of storage in artificial saliva). The margins were classified as "continuous" and "non-continuous" and the percentage of continuous margins (PCM) was statistically analyzed (α = 0.05). RESULTS: In most experimental groups, thermocycling led to a significant decrease in PCM, while the additional 8-week aging had no significant effect. F-20 + performed significantly better (p = 0.005) after 8 weeks storage in artificial saliva than the reference material with adhesive, while no statistically significant differences were observed at the other two time points. C-20 + exhibited significantly better PCM than the reference material with adhesive after thermocycling (p = 0.026) and after 8 weeks (p = 0.003). CONCLUSIONS: Overall, the experimental composites with BG showed at least as good marginal adaptation as the commercial reference, with an indication of possible re-sealing of marginal gaps. CLINICAL RELEVANCE: Maintaining or improving the marginal integrity of composite restorations is important to prevent microleakage and its likely consequences such as pulp irritation and secondary caries.

Repair of monolithic zirconia restorations with different direct resin composites: effect on the fatigue bonding and mechanical performance.

OBJECTIVE: The study aims to evaluate the shear bond and flexural strength fatigue behavior of yttrium-stabilized zirconia (4YSZ) repaired using different resin composites. MATERIALS AND METHODS: Cylindric specimens of 4YSZ were obtained for the bond strength (Ø = 6 mm, 1.5 mm of thickness) and biaxial flexural strength (Ø = 15 mm, 1 mm of thickness) fatigue tests and divided into 3 groups according to the repair resin composite: EVO (nanohybrid), BULK (bulk-fill), and FLOW (flowable). The zirconia surface was air-abraded with alumina particles, a 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) primer was applied, and the resin composite was build-up over the zirconia. Fatigue shear bond strength and flexural fatigue strength tests were performed (n = 15). One-way ANOVA and Tukey post hoc tests were carried out for both outcomes, besides scanning electron microscopy and finite element analysis. RESULTS: The repair material affected the fatigue shear bond strength of zirconia ceramic. The BULK group (18.9 MPa) depicted higher bond strength values than FLOW (14.8 MPa) (p = 0.04), while EVO (18.0 MPa) showed similar results to both groups. No effect was observed for the mechanical behavior (p = 0.53). The stress distribution was similar for all groups. CONCLUSION: The repair of yttrium-stabilized zirconia (4YSZ) ceramics with bulk-fill resin composites was the best option for high fatigue bond strength. However, the fatigue mechanical performance was similar regardless of the applied repair material. CLINICAL RELEVANCE: The repair of yttrium-stabilized zirconia (4YSZ) monolithic restorations may be performed with nanohybrid and bulk-fill resin composites in order to promote longevity in the treatment.

Clinical performance of a glass-hybrid system in comparison with a resin composite in two-surface class II restorations: a 5-year randomised multi-centre study.

OBJECTIVE: To evaluate the 5-year clinical performance of a glass hybrid restorative system and a nano-hybrid resin composite in moderate to large two-surface class II cavities. MATERIALS AND METHODS: This study was carried out by dental schools in Zagreb, Croatia; Izmir, Turkey; Belgrade, Serbia; and Milan, Italy. A total of 180 patients requiring two class-II two-surface restorations in the molars of the same jaw were recruited. The teeth were randomly restored with either a nano-hybrid resin composite (Tetric EvoCeram, Ivoclar Vivadent) or a glass-hybrid material (EQUIA Forte, GC). During the 5-year follow-up, two calibrated evaluators at each centre scored the restorations annually using the FDI-2 scoring system. The survival rates were calculated using the Kaplan-Meier method and compared using non-parametric matched pair tests (p < 0.05). RESULTS: There were no statistically significant differences between the overall survival and success rates of the two types of restorations (p>0.05). The success rates (FDI-2 scores 1-3) for EQUIA Forte were 81.9% (average annual failure rate: 3.9%) and 90.7% for Tetric EvoCeram (average annual failure rate: 1.9%). The survival rates (FDI-2 scores 1-4) for EQUIA Forte and Tetric EvoCeram were 94.5% and 94.4%, respectively, with an average annual failure rate of 1.1%. CONCLUSIONS: In terms of success and survival rates, both the glass-hybrid restorative system and the nano-hybrid resin composite have been shown to perform satisfactorily. CLINICAL RELEVANCE: The results of this study indicate that EQUIA Forte can be one of the therapeutic options for moderate to large two-surface class II restorations of posterior teeth.

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

OBJECTIVE: This 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 METHODS: A 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. RESULTS: All 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. CONCLUSION: The two-year clinical performance of dual-cure BFRC was comparable to light-cure BFRCs in Class ӀӀ restorations. CLINICAL RELEVANCE: Dual- and light-cure BFRCs showed excellent clinical performance in Class ӀӀ restorations after a 2-year clinical follow-up.

The radiographic evaluation of 11 different resin composites.

Radiopacities of dental materials used in restorations are very important in making the radiographic diagnosis. Therefore, the aim of our study was to evaluate the radiopacity of five single-shade and six simplishade resin composites with digital technique. Five different single-shade (Charisma Topaz One, Omnichroma, Clearfil Majesty ES-2 Universal, Vittra APS Unique, ZenChroma) and six different simplishade resin composites (G-aenial A'CHORD, Essentia Universal, OptiShade, Estelite Asteria, Filtek Universal, Filtek Z250) were used. For each group, five disk-shaped resin composites of 1 mm and 2 mm thicknesses were prepared. As a control, tooth slices with 1 mm and 2 mm thicknesses and a 99.5% pure aluminum step-wedge were used. The samples, tooth slices, and a step-wedge were placed on a photostimulable phosphor plate. Digital radiographs were taken from 30 and 40 cm distances (70 kVp, 7 mA 0.28 ms). The images were analyzed using ImageJ software to measure the mean gray values. Data were analyzed using SPSS 22 package program and Kruskal-Wallis H Test (p < 0.05). The highest radiopacity was seen in Filtek Universal at both distances and thicknesses. Omnichroma had the lowest radiopacity in all parameters. All specimens showed higher radiopacity than dentin. Except for Omnichroma 1 and 2 mm thick, Clearfil Majesty ES-2 Universal 2 mm thick, samples showed higher radiopacities than enamel (p < 0.05). The restorative materials tested were found to be more radiopaque than dentin. The samples passed the International Organization for Standardization for radiopacity values. The radiopacity values were affected by thickness and type of materials.

Effects of pre-heating on physical-mechanical-chemical properties of contemporary resin composites.

This research assessed the effects of pre-heating on the physical-mechanical-chemical properties of different resin composites. For this, resin composites were evaluated in 6 levels: Admira/ADM, Vitra/VIT, Filtek Supreme/FS, Filtek Supreme Flowable/FSF, Filtek One/FO, and Filtek Bulk Fill Flowable/FBF; temperature was evaluated in 4 levels using a composite heater: room temperature/22 ºC, 37 ºC, 54 ºC, and 68 ºC. Response variables were: degree of conversion/DC, flexural strength/FS and color stability/ΔE (immediately after light curing/LC, after 7 days of dark-dry-storage, and after 24 h and 3 days of artificial aging in water at 60 ºC). Data were subjected to 2-way ANOVA (DC and FR) and 3-way repeated measurements ANOVA (ΔE), all followed by Tukey's test (α = 5%). DC were similar (FBF, FS, and FSF) or increased (ADM, FO, and VIT) as the temperature increased. Results of FR were unchanged or increased for all composites except VIT and ADM. High-viscosity composites (VIT and FS) showed higher FR values than low-viscosity composite (FSF). For bulk-fill composites, FBF and FO showed similar results, but lower than high-viscosity composites. Results of color stability showed acceptable values up to 3 days aging except for ADM and FSF. ΔE was not influenced by pre-heating and, overall, ΔE: FS < VIT < FO < FSF < ADM < FBF. Only VIT and FS showed ΔE ≤ 3.3 (clinical threshold). Therefore, the effects of pre-heating depend on the material. The tested materials generally showed similar or enhanced properties after pre-heating (except ADM and VIT).

Transitioning from injectable resin composite restorations to resin composite CAD/CAM veneers: A clinical report.

OBJECTIVE: To describe a shift from injectable resin composite technique to composite resin computer-aided design and computer-aided manufacturing (CAD/CAM) veneers in addressing esthetic concerns associated with diastemas between anterior lower teeth in a clinical case. CLINICAL CONSIDERATIONS: Among several techniques proposed for direct resin composite restoration, the "Injectable resin composite technique" has gained popularity for its time-efficiency, reduced technique sensitivity, and diminished reliance on clinician skills. However, challenges such as staining and the need for frequent polishing follow-ups may prompt the consideration of more stable alternatives such as indirect veneer restorations. While ceramic veneers offer superior mechanical and optical properties, resin ceramic veneers, especially those milled from CAD/CAM resin ceramic blocks, offer advantages such as rapid, cost-effective production, simplified intra-oral repairs, less susceptibility to fracture, superior stress absorption, and requires minimal tooth preparation, making them an appealing option for many patients. Moreover, a fully-digital approach not only streamlines the process but also saves time and labor while ensuring the delivery of high-quality restorations to patients. CONCLUSION: In addressing a patient's dissatisfaction with constant polishing of direct resin composite restorations, a shift to resin composite CAD/CAM veneers was implemented. Utilizing a fully-digital approach with CAD/CAM resin ceramic restorations successfully restored both esthetics and function. CLINICAL SIGNIFICANCE: While the injectable resin composite technique achieves immediate esthetic results, its low color stability necessitates frequent polishing sessions. The replacement of direct resin composite restorations with CAD/CAM resin composite veneers becomes a viable option for patients seeking more stable restorations that require fewer follow-ups. This transition addresses both esthetic concerns and the need for enduring solutions in restorative dentistry.

Influence of in-office whitening on the color matching and surface characteristics of single-shade resin composites.

OBJECTIVE: The color matching of single-shade resin composites after in-office whitening was investigated. MATERIALS AND METHODS: Four single-shade resin composites were used. A total of 35% hydrogen peroxide was used as the whitening agent. The resin composite was placed in a cavity of an artificially discolored bovine tooth. The color differences between the restoration and surrounding enamel before and after whitening were determined based on ΔE*ab, ΔE00, and ΔWID. The color stability, surface roughness (Sa), and surface gloss (GU) of the resin composite alone were also evaluated. Statistical analyses were performed using repeated-measures analysis of variance with the Tukey-Kramer test. RESULTS: Based on the 50:50% of perceptibility and acceptability thresholds of ΔE*ab and ΔE00, none of the resin composite restorations were clinically acceptable before or after whitening. Regarding ΔWID, although all resin composites showed "acceptable match" in the baseline, they showed "mismatch" after the third session of whitening. Most of the resin composites alone were stable in color against whitening. CONCLUSIONS: Although the single-shade resin composites failed to achieve the expected color matching on discolored teeth either before or after the whitening, the impact of the whitening on the color of the resin composite alone may be negligible.

Evaluation of surface microhardness and gingival marginal adaptation of three different bulk-fill flowable resin composites: A comparative study.

OBJECTIVES: To evaluate surface microhardness and gingival marginal adaptation of three different bulk-fill flowable resin composites (FB-RBCs) in Class V cavities with enamel or dentin margins before and after thermocycling (TMC). MATERIALS AND METHODS: Three available FB-RBCs were used; Palfique Bulk Flow (PaBF) (Tokuyama Dental), SDR Flow+ Bulk Fill Flowable (Dentsply Sirona), and I-Flow Bulk Fill (I-Dental). Thirty discs were prepared from each type of FB-RBCs. The discs were subjected to Vickers microhardness tester machine. Class V cavities were prepared on 180 molars. Gingival margins of half the specimens were prepared above CEJ and the other half below CEJ. Cavities were restored with FB-RBCs for gingival marginal adaptation test. Two-way ANOVA was used in microhardness, while three-way ANOVA was used for marginal adaptation. RESULTS: The used materials showed statistically significant differences in microhardness and marginal adaptation. CONCLUSIONS: Regarding microhardness, PaBF showed the highest value before TMC and SDR was the highest after TMC. Regarding marginal adaptation, SDR revealed the best marginal adaptation than PaBF and I-flow, either subjected to TMC or not. CLINICAL SIGNIFICANCE: The longevity of cervical restorations depend on both the location of the cavity margin and the material used. The microfractures in resin composite surface due to low surface microhardness as well as marginal gaps seen in laboratory studies could be considered as an indicative parameter for clinical problem associated with marginal differences.

A fully digital workflow involving 3D printed tooth reduction guides and injection resin-indexes to restore an impacted canine.

OBJECTIVE: The present clinical report describes a long-term temporary restorative approach using injectable composite to reshape a canine into a central incisor, within the context of an ongoing orthodontic treatment. This treatment protocol describes a fully-digital workflow, incorporating digital designed and 3D printed diagnostic wax up, reduction guides and resin-injection index. CLINICAL CONSIDERATIONS: Effective planning is important when aiming to deliver a comprehensive and multidisciplinary workflow, and digital tools serve as invaluable aids. CONCLUSION: The use of a fully digital workflow in a comprehensive dental treatment resulted in a predictable and successful outcome for a restoration of a canine that was transformed into a central incisor. CLINICAL SIGNIFICANCE: This approach highlights the efficacy of digital technology in achieving precise and successful dental restorations, emphasizing its significance in modern dental practice.

Three dimensionally printed template with an interproximal isolation design guide consecutive closure of multiple diastema with injectable resin composite.

OBJECTIVE: This article describes a novel 3D-printed template armed with interproximal matrices to isolate interproximal contact areas and guide injectable resin composite for consecutive closure of multiple diastema. CLINICAL CONSIDERATIONS: Among several treatment options proposed for diastema closure, direct resin composite is noninvasive and easy to repair. The "composite injection technique" has been introduced to improve time efficiency and reduce technique sensitivity for clinicians. However, in the case of multiple diastema, the overflow of excess resin materials onto the adjacent teeth during injection poses challenges for recontouring the interproximal anatomy. A 3D-printed template with special-designed gaps at interproximal areas was designed and fabricated based on a virtual diagnostic wax-up. Flowable resin composite was then consecutively injected through the template to close diastemata at multiple adjacent teeth. CONCLUSION: This technique using a 3D-printed template with interproximal isolation design contributed to an efficient and accurate operation for multiple anterior diastema closure. CLINICAL SIGNIFICANCE: Efficient and accurate freehand buildups of composite restoration for multiple diastema are challenging in operative dentistry. The described noninvasive full digital workflow provides a predictable method to accurately recontour the multiple target restorations and reduce the chair-side time and technical sensitivity.

Synthesis and characterisation of microcapsules for self-healing dental resin composites.

AIM: The purpose of this study was to i) synthesise TEGDMA-DHEPT microcapsules in a laboratory setting; ii) characterise the resultant microcapsules for quality measures. MATERIALS & METHODS: Microcapsules were prepared by in situ polymerization of PUF shells. Microcapsules characterisation include size analysis, optical and SEM microscopy to measure the diameter and analyse the morphology of PUF microcapsules. FT-IR spectrometer evaluated microcapsules and benzyl peroxide catalyst polymerization independently. RESULT: Average diameter of TEGDMA-DHEPT microcapsules was 120 ± 45 µm (n: 100). SEM imaging of the capsular shell revealed a smooth outer surface with deposits of PUF nanoparticles that facilitate resin matrix retention to the microcapsules upon composite fracture. FT-IR spectra showed that microcapsules crushed with BPO catalyst had degree of conversion reached to 60.3%. CONCLUSION: TEGDMA-DHEPT microcapsules were synthesised according to the selected parameters. The synthesised microcapsules have a self-healing potential when embedded into dental resin composite as will be demonstrated in our future work.

The optical behavior of nano filled resin composite loaded with graphene oxide nanoparticles.

OBJECTIVES: Assessment of the effect of incorporation of graphene oxide nanoparticles (GONPs), different concentrations into resin composite with different thicknesses on its color modulation. MATERIALS AND METHODS: GONPs were prepared using the chemical reduction method and characterized using a transmission electron microscope and X-ray diffraction. The minimum concentrations of GONPs that provided the most effective antibacterial action (0.05 wt% and 0.2 wt%.) were prepared to be the concentration added to the tested resin composite. Calculations were done to find the required volume of the GONPs solution needed according to the mass of the resin composite. 70 nano-filled resin composite discs were prepared with 10 mm diameter × 3 mm height. 10 resin composite discs were prepared without GONPs incorporation and served as a control (G0). The other 60 resin composite specimens were divided into 2 equal groups (G1& G2) according to the concentration of the loaded nanoparticles in the specimens. Each group was divided into 3 equal subgroups according to the thickness of the resin composite containing GONPs; [T1: GONPs dispersed in the bottom 1 mm of the disc, while the top 2 mm of the disc was of resin composite only. T2: GONPs dispersed only in the bottom 2 mm of the disc and T3: GONPs dispersed in the total thickness of the disc (3 mm)]. ∆E values were calculated using a Vita Easy shade Spectrophotometer. RESULTS: Incorporation of GONPs into resin composite induced significant color change and among all the 6 experimental groups, G1T1 group (of 0.05 wt% concentration GONPs dispersed only in the bottom 1 mm of the disc) showed a non-significant color change. CONCLUSION: Dispersion of GONPs has a detectable effect on the color change of resin composite. Meanwhile, dispersion in low concentration for only the bottom 1 mm thickness of resin composite has an undetectable effect on its color.

Impact of repeated preheating of bulk-fill resin composite on postoperative hypersensitivity; a randomized controlled clinical trial.

BACKGROUND: This clinical study was conducted aiming to evaluate the impact of repeated preheating of bulk-fill resin composite on postoperative hypersensitivity. METHODS: A total of 105 eligible, consenting adults were recruited. Patients had posterior teeth suffering from proximal decay with no signs of irreversible pulpitis. Patients were prepared for Class II restorations and restored with bulk-fill resin composite. Patients were randomized into three groups of 35 patients according to the number of preheating cycles for the resin composite syringe used; group I: no preheating; control group at room temperature, group II: Resin composite preheated once, and group III: Resin composite preheated ten cycles. Patients were assessed for postoperative dentin hypersensitivity using the visual analogue scale (VAS) at three-time intervals: day one, one week and by the end of one month after restorative treatment. Statistical analysis was performed; ANOVA with a single factor was used to test for significance at a p value ≤ 0.05. For nonparametric data, the Kruskal‒Wallis test was used to compare the three testing groups. Friedman's test was used to study the changes within each group. Dunn's test was used for pairwise comparisons when the Kruskal‒Wallis test or Friedman's test was significant. RESULTS: The scores of the three groups through the three time intervals were almost zero except for the first day where VAS scores were recorded with maximum score of 3 for groups I and II. Groups II and III; there was no statistically significant change in hypersensitivity scores by time with P-values 0.135 and 0.368, respectively. However, for group I there was a significant difference from VAS score recorded on first day and the two following time intervals. CONCLUSION: The repeated preheating cycles of bulk-fill resin composite prior to curing had no adverse effect on the patients regarding postoperative dentin hypersensitivity. This information could be of utmost significance, as the same resin composite syringe can undergo numerous preheating cycles clinically before it is completely consumed with the advantage of improvement on the handling properties. TRIAL REGISTRATION: The protocol of the current study was registered at www. CLINICALTRIALS: gov , with the identification number NCT05289479 on 21/03/2022. All procedures involving human participants were performed in accordance with the ethical standards of the Research Ethics Committee of the Faculty of Dentistry, Minia University, Egypt, under the approval number 73/440 on 11/09/2020.

Dental biomaterials redefined: molecular docking and dynamics-driven dental resin composite optimization.

BACKGROUND: Dental resin-based composites are widely recognized for their aesthetic appeal and adhesive properties, which make them integral to modern restorative dentistry. Despite their advantages, adhesion and biomechanical performance challenges persist, necessitating innovative strategies for improvement. This study addressed the challenges associated with adhesion and biomechanical properties in dental resin-based composites by employing molecular docking and dynamics simulation. METHODS: Molecular docking assesses the binding energies and provides valuable insights into the interactions between monomers, fillers, and coupling agents. This investigation prioritizes SiO2 and TRIS, considering their consistent influence. Molecular dynamics simulations, executed with the Forcite module and COMPASS II force field, extend the analysis to the mechanical properties of dental composite complexes. The simulations encompassed energy minimization, controlled NVT and NPT ensemble simulations, and equilibration stages. Notably, the molecular dynamics simulations spanned a duration of 50 ns. RESULTS: SiO2 and TRIS consistently emerged as influential components, showcasing their versatility in promoting solid interactions. A correlation matrix underscores the significant roles of van der Waals and desolvation energies in determining the overall binding energy. Molecular dynamics simulations provide in-depth insights into the mechanical properties of dental composite complexes. HEMA-SiO2-TRIS excelled in stiffness, BisGMA-SiO2-TRIS prevailed in terms of flexural strength, and EBPADMA-SiO2-TRIS offered a balanced combination of mechanical properties. CONCLUSION: These findings provide valuable insights into optimizing dental composites tailored to diverse clinical requirements. While EBPADMA-SiO2-TRIS demonstrates distinct strengths, this study emphasizes the need for further research. Future investigations should validate the computational findings experimentally and assess the material's response to dynamic environmental factors.

Influence of thickness and restorative system on the mechanical behavior of CAD/CAM minimally invasive occlusal veneers - in vitro study.

AIM: The aim of this study was to evaluate the physical-mechanical behavior of the occlusal veneers when subjected to thermomechanical cycling. MATERIALS AND METHODS: Sixty specimens were divided into 04 groups (n=15 per group), according with the different restorative materials and thicknesses: material - lithium dissilicate LD (IPS e.max CAD, Ivoclar Vivadent) and nano- ceramic-resins NCR (ESPE Lava Ultimate, 3M); thickness - 0.6 and 1.2mm. The occlusal veneers were bonded over human flattened fresh extracted molars with dual-polymerizing luting agent (Variolink N, Ivoclar Vivadent and RelyX Ultimate 3M) using the respective adhesive system following the selective-etch technique (self-etch in dentin and total etch in enamel). The resin cement was light cured for 40 seconds each face, using a LED light cure equipment (BlueStar II, Microdont, 1100 mW/cm2). The response variables consisted of veneer survival rates (crack formation, catastrophic cracks and debonding) when subjected to thermal cycling from 5° to 55° C and simultaneous mechanical cycling performed at load intensities of 100, 200, 300, 400 and 450N for 20,000 cycles each. RESULT: Data were submitted to the Kruskall Wallis test and Pairwise Comparison, adopting a significance level of 5%. NCRs presented a lower incidence of failures (p<0.05) when compared to LD. According to thickness factor, 1.2mm thick occlusal veneers withstand higher cycling loads. CONCLUSION: NCR occlusal veneers with 1.2mm thickness presented superior physical-mechanical behavior than lithium disilicate and 0.6mm restorations.

Color Stability of Bioactive Restorative Material vs Nanohybrid Resin Composite: An In Vitro Study.

AIM: This study aimed to assess the color stability of bioactive restorative materials vs nanohybrid resin composites after 3 months of immersion in three frequently consumed beverages. MATERIALS AND METHODS: Thirty disk-shaped specimens of Giomer dental restorative material (Shofu, Japan) and nanohybrid resin composite (Tokuyama, Japan) were performed using a Teflon mold. Super-Snap system (Shofu, Japan) was utilized to finish and polish the specimens to be preserved for 24 hours in distilled water at 37°C. The samples had been divided into three subgroups (Coffee, tea, Pepsi) (n = 5). The initially displayed color measurements of the samples were performed using a spectrophotometer (VITA Easyshade® V). After 7 days, 30 days, and 90 days, color measurements were repeated, and the E of each sample was estimated. E of each sample was calculated. RESULTS: The Giomer group showed statistically significant higher E values than the nanohybrid resin composite where the p-value was ≤0.0001. Tea subgroup showed the highest statistically significant E values in both groups where the p-value was ≤ 0.0001. The highest statistically significant color change was recorded at 3 months. CONCLUSION: The color of bioactive restorative material is less stable if compared with nanohybrid resin composite. CLINICAL SIGNIFICANCE: As tea and coffee are popular beverages, particularly in Middle Eastern nations, dentists must advise patients about the color change of resin restorations. Patients are advised to brush their teeth immediately after consuming these beverages. How to cite this article: Saber EH, Abielhassan MH, Abed YA, et al. Color Stability of Bioactive Restorative Material vs Nanohybrid Resin Composite: An In Vitro Study. J Contemp Dent Pract 2024;25(3):221-225.

Progressive Tooth Wear Against Resin-Based Restorative Composites.

PURPOSE: The composition and properties of resin-based composite materials could affect tooth wear and lead to clinical problems. Therefore, the study objective was to characterize human tooth wear behavior against a bulk-fill restorative (BF) compared to a conventional resin composite (RC) and a CAD/CAM resin nano ceramic (RN). METHODS: Square-shaped specimens of each material were prepared and sub-divided according to the number of testing cycles (n=8): 100,000, 250,000, and 500,000 cycles. An occlusal wear test was performed using a chewing machine with 49 N, 2 Hz, in 37°C distilled water. Human premolar cusps were used as antagonists. Micro-CT and laser scanner were used to scan antagonists and specimens, respectively. Wear volume was assessed using a software and the wear pattern was examined with SEM. Softening in solvent analysis was performed by measuring the materials' Knoop microhardness (KHN) before and after immersion in ethanol. Wear volume data were analyzed with two-way ANOVA and Student-Neuman-Keuls test (α=0.05). RESULTS: For tooth and specimen wear volume, there was statistical significance for material and number of cycles, but not for the interaction between factors. BF resulted in less tooth (p=0.008) and specimen (p=0.030) wear than RN and RC, which were similar (p⟩0.05). Volume loss increased from 100,000 to 500,000 cycles. BF showed the lowest microhardness (KHN1); and %ΔKHN similar to RC, but greater than RN. CONCLUSION: BF induced less volume loss to the tooth than RC and RN, while presenting greater wear resistance. The tooth wear pattern and damage progression were mild for all materials. CLINICAL SIGNIFICANCE: Resin composites show favorable wear behavior, leading to low volume loss and mild structural damage of the tooth. Regular bulk-fill resin composite stands out for its efficient restorative technique, low wear susceptibility and reduced capacity to wear down the tooth.