Nanohybrid Composite Resin Research Articles

Comparative evaluation of surface roughness and bacterial adhesion on two bioactive cements: an in-vitro study

BackgroundDental restorative materials are recognized as artificial niches that facilitate the adherence and accumulation of oral microorganisms. To mitigate oral diseases and extend the lifespan of restorations, it is advantageous to use dental materials that exhibit low susceptibility to bacterial adhesion.ObjectiveTo evaluate and compare bacterial adhesion on two bioactive restorative materials, a glass hybrid restorative, and an alkasite with a nanohybrid resin composite as a positive control. The secondary objectives were to compare the surface roughness (SR) of the materials and determine the correlation between the bacterial adhesion and the SR.Materials and methodsThe samples consisted of 33 polished discs of each material: Group A: Tetric® N-Ceram (nanohybrid resin composite), Group B: Equia Forte™ HT Fil (glass hybrid restorative) and Group C: Cention N® (alkasite). Streptococcus mutans cultures were inoculated and after 24-hours of incubation, bacterial adhesion was measured by measuring optical density (OD) and number of colony forming units (CFUs). After 96-hours incubation, the bacterial cell count was determined using scanning electron microscopy (SEM). SR was assessed using surface profilometer.ResultsAlkasite had significantly lower OD and CFUs (p < 0.001 and p = 0.015 respectively). According to the SEM analysis, the glass hybrid restorative had lower mean bacterial cell count with no significant difference between the groups. The nanohybrid composite had the smoothest surface that was significantly lower than the alkasite and glass hybrid restorative (p = 0.002). None of the groups demonstrated a correlation between bacterial adhesion and SR.ConclusionAlkasite impedes bacterial adhesion better than the glass hybrid restorative and nanohybrid composite, while smoother surfaces are achieved with the nanohybrid composite.

Effect of Pempek Vinegar on Composite Resin Hardness Nanohybrid

Background: Nanohybrid composite resin is a dental restorative material that is widely used in modern dental practice. However, the interaction of these materials with acidic foods and drinks, such as pempek vinegar, can affect their mechanical properties. Materials and Methods: This research is laboratory experimental research with pretest-posttest with only group design. In this study, nanohybrid composite resin was used in the form of a circle on a mold with a thickness of 2 mm and a diameter of 10 mm which was immersed in a solution of pempek vinegar. The number of samples used is 6 samples with 4 test groups. The 4 test groups were divided into immersion times of 1,3,5,7 days. Results: After immersion, the results of the hardness of the composite resin were taken. Using the normality and homogeneity tests, the hardness test results data were processed. It was found that the data were normally distributed and not homogeneous for each data group. After that an analysis was carried out using independent t-test (p &lt;0.005) it was found that there was a significant effect of the hardness of the composite resin on immersion in Pempek vinegar solution which was soaked for 3 days, 5 days and 7 days. Conclusion: Pempek vinegar solution affects the surface hardness of the nanohybrid composite resin which is probably influenced by pH, liquid absorption ability, and soaking time.

A Spectrophotometric Evaluation of Effect of Tea, Coffee, Cola Beverage, and Juice on Color Stability of Microhybrid and Nanohybrid Resin Composites: In Vitro Study

A Spectrophotometric Evaluation of Effect of Tea, Coffee, Cola Beverage, and Juice on Color Stability of Microhybrid and Nanohybrid Resin Composites: In Vitro Study

Three-year clinical performance of direct restorations using low-shrinkage Giomer vs. nano-hybrid resin composite

ObjectivesThe objective of this investigation was to compare the clinical performance of a nano-hybrid resin composite and a low-shrinkage Giomer resin composite.Material and methodsIn total, 35 pairs of restorations were performed using either low-shrinkage Giomer (Beautifil II LS, Shofu Inc.) or nano-hybrid (Clearfil Majesty Posterior) resin composite in 35 patients by two operators using the relevant adhesives, i.e., FL-Bond II (Shofu Inc.) and Clearfil SE Bond (Kuraray), with the self-etching technique according to each manufacturer's instructions. Two clinicians assessed the restorations 2 weeks (baseline); 6 months; and 1, 2, and 3 years after the restorative procedures using FDI (World Dental Federation) criteria (Scores 1–5). Data were analyzed using the marginal homogeneity and McNemar tests. The survival rate was calculated using Kaplan–Meier survival analysis and the survival of the two groups was compared with the log-rank test (p = 0.05).ResultsThe mean observation period was 37.7 ± 6.8 months. All restorations completed their 3-year follow-up. The criteria were mainly rated with high (1 or 2) scores for quality in both groups. Only one restoration in the low-shrinkage Giomer resin composite group was accepted as a failure at the 2-year recall due to retention loss.ConclusionAt the 3-year follow-up, the performance of the restorations using the Giomer and the nano-hybrid resin composite were similar and clinically acceptable.Clinical relevanceThe low-shrinkage Giomer resin composite exhibited a similar clinical performance to the nano-hybrid resin composite after 3 years in service with both materials displaying minor surface deteriorations at the 3-year recall.Clinical Trial Registrationhttps://clinicaltrials.gov, identifier: NCT02823769.

Evaluating the clinical significance of color stability in nanohybrid composite resins: a comparative study of local and international brands

Aims: The objective of this study was to evaluate the color stability of five nanohybrid composite resins, including locally produced Turkish brands and an international brand, after exposure to staining and brushing simulations over time. Methods: Five nanohybrid composite resins; Filtek Z550 (FLT), Dolgunn (DLG), RubyComp Nano (CMP), Nova Compo C (NVC), and Parion (PRN) were tested. Specimens underwent staining and brushing simulations designed to replicate clinical oral conditions. The staining process involved immersing the specimens in a coffee solution for 8 hours per day over a 10-day period to simulate short-term staining (t1), and for 12 days to simulate long-term staining equivalent to 1 year (t2). Brushing cycles were used to replicate the mechanical wear caused by daily oral hygiene practices. Color measurements were recorded at baseline (t0), after 10 days of staining (t1), and after 1 year of simulated staining and brushing (t2). Additional analyses were conducted using Energy-dispersive X-ray spectroscopy (EDX) and Scanning Electron Microscopy (SEM) to investigate structural and surface characteristics. Statistical analysis was performed using generalized linear models and two-way robust ANOVA to assess the significance of differences in color stability, with a significance level set at p

Quantification of Color Variation of Various Esthetic Restorative Materials in Pediatric Dentistry.

The goal of this paper is to find an association between the staining capacity of dental restorations used in pediatric patients and food items and to develop an optimum model to predict the most informative factor that causes the highest amount of color change through machine learning algorithms. Color changes in restorative materials occur as a result of intrinsic and extrinsic factors, such as the type of restorative material, food items used, polished status of the material, and time interval. This was an "in vitro study" conducted at Aligarh Muslim University, Aligarh, Uttar Pradesh, India. The study included 200 specimens, that is, 40 in each group A (orange juice), group B (Amul Kool Café), group C (Pepsi), group D (Amul Kesar Milk), and group E (artificial saliva). The materials were glass ionomer cement (GIC), resin-modified glass ionomer cement (RMGIC), microhybrid composite resin, and nanohybrid composite resin. These were further divided into polished and unpolished groups. The optimum modeling of the prediction of color change in materials by different effective factors was done by machine learning decision tree. We applied two algorithms: Chi-square automatic interaction detector (CHAID) and classification and regression tree (CART). In prediction modeling in the decision tree by CHAID and CART, color change is taken as the dependent variable, and group (type of restorative material), food items, time interval, and polished status are taken as independent variables. The various beverages caused significant color variation due to different pigmentation agents. The agent that caused the highest color change was Kool Café. The Kesar Milk had the lowest pigmentation capacity. The greatest color variation was found on Glasionomer FX-II submerged in Pepsi and the least on Ivoclar Te-Econom Plus in Kesar Milk. The mean absolute error for the training dataset in the CART model and CHAID model is 0.379 and 0.332, and for the testing data set, it is 0.398 and 0.333, respectively. Therefore, the prediction of color change by the CHAID model is optimum, and we found that the restorative materials have a maximum predictor importance of 0.86 (86%), time interval 0.07 (7%), food items 0.04 (4%), and polished status has the least importance, that is, 0.03 (3%). The staining capacity of restorative material highly depends on the material itself, the initial time interval, and least on the food items used. The clinical performance of dental restorations could be affected by various beverages consumed by children. This study thus provides important clinical insights into esthetic dentistry by offering valuable information on long-term color stability and the effect of polishing on common esthetic restorative materials used in pediatric dentistry. Varshney P, Khan SY, Jindal MK, et al. Quantification of Color Variation of Various Esthetic Restorative Materials in Pediatric Dentistry. Int J Clin Pediatr Dent 2024;17(7):754-765.

Effect of Finishing Protocol on Obtaining and Maintaining Gloss in Four Nanohybrid Resin Composites.

Within the clinical objectives of performing direct restorations with resin composites is the achievement of an optimal surface in mechanical terms, while also resembling the natural optical characteristics of dental enamel. The aim of this study is to compare the gloss levels achieved in four nanohybrid resins using four different finishing/polishing (F/P) protocols and assess the retention of gloss after an aging process. Forty-eight A2-colored samples from four commercial brands (Filtek Z250 XT, Tetric N-Ceram, Zafira, and Spectra Smart) were prepared, with 12 specimens per resin. The samples were divided into four subgroups based on the F/P treatment: T1 (clinical polishing sequence with ShapeGuard system), T2 (metallographic polishing sequence), T3 (clinical polishing sequence with PermaSeal), and T4 (final polymerization through glycerin and clinical polishing sequence). Gloss measurements were taken before and after aging.ANOVA one-way was done. Before aging, Z250 showed the highest average gloss in T1 (77.2 gloss units - GU), while Zafira (43.8 GU), Tetric (39.5 GU), and Spectra (33.5 GU) had lower values. In T2, Zafira (92.7 GU) and Spectra (87.4 GU) had the highest average gloss, and Tetric (75.7 GU) and Z250 (78.3 GU) had the lowest. No significant differences were found in T3, and in T4, Z250 had the highest average gloss (78.9 GU), followed by Tetric (74.7 GU) and Zafira (52.5 GU), with Spectra having the lowest (42.7 GU). Control group gloss levels ranged from 61.8 to 71.8 GU and remained consistent after aging, except for Tetric in T1 (p=0.045). The impact of F/P strategies on gloss retention varies with the material, even within the same resin composite classification. The initial gloss level appears to be a more critical factor for long-term gloss retention than the specific F/P protocol used.

Comparison of Class II Bulk-Fill, Self-Adhesive Composites, Alkasite, and High-Viscosity Glass Ionomer Restorations in Terms of Marginal and Internal Adaptation.

(1) Background: Restoring decayed teeth in young patients can be challenging. This calls for a simplification of the protocols through new biomaterials. Therefore, the aim of this study was to compare the marginal adaptation delivered by restorative materials applied on class II cavities by using a simplified protocol, before and after fatigue test, followed by the assessment of the internal adaptation. (2) Methods: Forty-eight human teeth were divided into six groups (n = 8). Dentinal fluid simulation was performed before restoring the class II cavities: Gr 1-adhesive (Clearfil Universal Bond Quick) and nanohybrid flowable composite (Clearfil Majesty ES Super Low Flow), Gr 2-adhesive (Clearfil Universal Bond Quick) and nanohybrid composite (Clearfil Majesty ES standard), Gr 3-bulk fill self-adhesive composite (Surefil One), Gr 4-bioactive powder-liquid filling material (Cention Forte), Gr 5-universal adhesive (Adhese Universal) and nanohybrid composite resin (Tetric Powerfill); and control group (CT)-high-viscosity glass ionomer (Equia Forte). Marginal adaptation was observed with scanning electron microscopy (SEM) and compared before and after a fatigue test consisting of repeated thermal and mechanical cycles. The specimens were then cut mesio-distally, and internal adaptation was undertaken using SEM again. Repeated measures and one way ANOVA followed by a Fisher's LSD test and Fisher's LSD post hoc test were used in order to compare the statistically significant differences among groups. (3) Results: As for the marginal adaptation after loading, Cention Forte (58%) and Equia Forte HT (53%) were statistically equivalent and presented the highest results, followed by Clearfil Majesty ES Standard (32%) and Tetric Powerfill (27%), with Surefil One (8%) and Clearfil Majesty ES Flow Super Low (7%) showing the worst results. In terms of internal adaptation, Cention Forte (85%) and Clearfil Majesty ES Standard (74%) had the highest percentages of continuous margins. Tetric powerfill (56%) and Equia Forte HT (44%) showed statistically significantly lower results, followed by Clearfil Majesty ES Flow Super Low (33%) and eventually Surefil One (17%). (4) Conclusions: This in vitro study showed promising results for the marginal and internal adaptation of alkasite dual cured Cention Forte in the restoration of class II cavities. This material could be considered an interesting restorative alternative for the restoration of deciduous teeth.

Comparative Evaluation of Microtensile Dentin Bond Strength and Interfacial Micromorphology of Three Universal Adhesives.

To assess and compare the microtensile dentin bond strength (μTBS) and interfacial micromorphology of three universal adhesives. 96 human molars were assigned to three universal adhesives: Single Bond Universal (SBU), CLEARFIL Universal Bond Quick (UBQ), and RE-GEN Universal Adhesive (REGEN). Adhesives were applied in self-etch mode. SBU and REGEN were applied following the manufacturers' instructions. UBQ was divided into two subgroups: one following the manufacturer's instructions (UBQ Short) and the other with an extended application time (UBQ Extended). Teeth were restored with nanohybrid resin composite. Specimens were divided into immediate and delayed subgroups. The delayed subgroups were stored for 6 months and subjected to 5000 thermocycles. μTBS was tested, and failure mode was analyzed. Interfacial micromorphology was assessed using a scanning electron microscope. The data were statistically analyzed (p⟨ 0.05). The adhesive choice, aging, and their interaction significantly affected μTBS. SBU exhibited the highest immediate μTBS, comparable to UBQ (Extended) and REGEN, and significantly higher than UBQ (Short). In delayed testing, SBU outperformed the other adhesives. Aging negatively affected the μTBS of UBQ and REGEN, while SBU wasn't affected. The quick application concept of UBQ deteriorated its μTBS compared to the extended application time.

Investigation of Various Finishing/Polishing Procedures on Color Stability of Composite Resins

Objective: The objective of this study was to assess the impact of various finishing and polishing systems on the color stability of composite resins treated with coffee. Methods: Fifty samples of each of nanohybrid and supra-nanohybrid composite resin materials were prepared and each material was randomly divided into 5 groups (n=10): Group 1: Control group (mylar strip), Group 2: One Gloss (one step), Group 3: One Gloss + polishing paste, Group 4: Soflex disk (multistep), Group 5: Soflex disk + polishing paste. The samples were colored in coffee solution for 144 hours to simulate six months of coffee consumption after polishing. The color of the samples before-after staining was measured with a spectrophotometer and ∆E00 values were calculated. Results: Material, polishing type and the interaction of these two parameters had a statistical effect on the color change values (p&amp;lt; 0,001). The ∆E00 values of supra-nanohybrid composite resin were higher than nanohybrid. Both materials exhibited color change above the thresholds of clinical perceptibility (PT&amp;gt; 0,8) and acceptability (AT&amp;gt; 1,8). In terms of polishing types, the highest ∆E00 was found in the control group and the lowest in the disk group. The additionally applied polishing paste caused a non-significant decrease in the color change of the single-step polishing system (p&amp;lt; 0,05) and a statistically significant increase in the multi-steps polishing system (p&amp;gt; 0,05). Conclusion: Considering the limitations of the study, it can be concluded that the use of multi-steps discs is more advantageous in preventing discoloration of composite resins.

Two-year clinical performance of indirect resin composite restorations in endodontically treated teeth with different cavity preparation designs: a randomized clinical trial

Trial designThis is a randomized, controlled, superiority, double-blinded, parallel-group, two-arms trial with an allocation ratio of 1:1. This study aimed to assess whether the cavity design could affect the clinical performance of the CAD/CAM generated indirect resin composite restoration in endodontically treated teeth (ETT) evaluated using the Modified USPHS criteria after a two-year follow up.MethodsA total of 30 participants who underwent endodontic treatment for MOD cavities in permanent molars were divided randomly into two parallel groups (n = 30 restorations) according to the performed cavity design to group 1 in which there was no cuspal reduction (inlay) and group 2 in which cuspal reduction was performed (overlay). All pulp chambers were filled with bulk fill flowable composite, and the cavities were prepared following the criteria of the cavities for indirect restorations and restored using nano-hybrid composite resin blocks (Brilliant, Coltene, Switzerland). The restorations were evaluated using the modified USPHS criteria at baseline, six months, one-year and two years follow-up visits. For qualitative data, frequencies (n) and percentages (%) were used to display the data, while mean and standard deviation (SD) were used for quantitative data. The normality of the data was evaluated using the Shapiro-Wilk and Kolmogorov-Smirnov tests. For every test, P ≤ 0.05 was used as the significance threshold.ResultsTwenty-six individuals completed the follow-up period after receiving the assigned intervention.The inter-group comparison showed that, at the 6- months and 12- months observation points, the overlay design had significantly better marginal adaptation, less incidence of discoloration or tooth/restoration fracture, and similar marginal integrity and caries incidence to the inlay design. After 24- months, the overlay design still had better marginal adaptation, less incidence of discoloration or tooth/restoration fracture and less caries incidence in comparison to the inlay design, while there was no difference in the marginal integrity between either design.Conclusions and clinical relevanceCuspal reduction in endodontically treated teeth showed better clinical performance than the cusp preservation thus, the former is more reliable.

Effects of Artificial Aging of Direct Resin Nano-Hybrid Composite on Mean Bond Strength Values for Veneer Ceramic Samples.

BACKGROUND This study investigates the effect of artificial aging of direct resin nanohybrid composites on mean bond strength values for veneer ceramic samples. MATERIAL AND METHODS Ninety direct nanohybrid composite resin (Tetric N-Ceram) cylindrical discs were divided into 5 groups (n=18 each) based on aging cycles (thermocycling), as follows: TC=no aging (control), T1=850, T3=2500, T6=5000, and T12=10000 cycles, representing 1, 3, 6, and 12 months of clinical usage, respectively. Lithium disilicate glass ceramic (IPS e.max Press) cylindrical discs were cemented to resin discs using resin cement (Variolink N) after surface treatments (ceramic etching, silaning, composite abrasion). Differences in means between subgroups were calculated using one-way ANOVA, followed by the Tukey honestly significant differences post hoc test. Differences were considered statistically significant with a P value ≤0.05. RESULTS The highest SBS between ceramic and aged composite was observed at 1 month (m=20.35) but did not differ significantly from the control group (m=20.97). For all other subgroups (3, 6, 12 months) SBS was significantly less than that of the control (P≤0.05). At 1 and 3 months, cohesive failures were more common, whereas adhesive failures were more common in 6- and 12-month-old composites. CONCLUSIONS SBS of aged composites was less than that of non-aged composites, with SBS decreasing proportionally as the resin aged. When cementing a ceramic restoration over existing composite restorations, those older than 1 month should be removed and replaced with new ones.

Comparison of Surface Roughness of Nanohybrid Composite Resin Immersed in Various Mouthwashes

Comparison of Surface Roughness of Nanohybrid Composite Resin Immersed in Various Mouthwashes

Surface roughness of supra-nano spherical filled and nanohybrid composite resin after Coffea arabica immersion: an experimental study

ABSTRACTIntroduction: Supra-nano spherical filled composite resin (Omnichroma, Tokuyama, Japan) with sol-gel method has 0.26 μm filler size, while nanohybrid composite resin (ENA HRi, Micerium, Italy) has 0.2-1 μm filler size. Nanofillers enhance resistance from chlorogenic acid contained in Coffea arabica. This study analyzed the surface roughness difference between supra-nano spherical-filled and nanohybrid composite resins after Coffea arabica immersion for 7 and 14 days, with 15 minutes of immersion each day. Methods: This study was an in vitro laboratory experiment with a pretest-posttest control group design. Twenty composite resin samples were immersed in artificial saliva and divided into four groups; supra-nano coffee, nanohybrid coffee, supra-nano saliva (control), and nanohybrid saliva (control). After 24 hours, immersion in Coffea arabica was started for supra-nano coffee group and nanohybrid coffee group for 15 minutes daily until days 7 and 14. Control groups were immersed in saliva. Results: One-way ANOVA showed significant differences in the surface roughness between composite resin groups. Post-hoc Tukey showed a significant difference between supra-nano coffee (0.91± 0.29 μm) and nanohybrid saliva (1.43±0.42 μm). The GLM Repeated Measure test showed significant surface roughness changes in supra-nano after 14 days of immersion in Coffea arabica (1.47±0.13 μm), while nanohybrid experienced surface roughness changes in 7 days of immersion in Coffea arabica (1.94±0.55 μm) and increased in 14 days (2.25±0.47 μm). In saliva immersion (control group), nanohybrid experienced an increase in surface roughness after 14 days, while supra-nano did not experience a significant increase in surface roughness. Conclusion: Supra-nano spherical filled composite resin exhibits greater resistance to changes in surface roughness following immersion in Coffea arabica.KEYWORDSCoffea arabica, nanohybrid, composite resin, supra-nano spherical filled, surface roughness

Radiopacity and Microleakage Evaluation of Different Intermediate Materials

Objective: The aim of this study is to compare the radiopacities of different types of materials with indications for application as a base under restorations and the microleakage of the final restorations with these materials applied as bases. Methods: Standart Class I cavities were prepared in 90 caries-free molar teeth. The cavities were randomly divided into 9 groups according to the type of intermediate material to be applied (n=10): 1. High flowable composite, 2. Low flowable composite, 3. Fiber reinforced composite, 4. Giomer, 5. Ormocer, 6. Alkasite, 7. Bioactive composite, 8. High viscosity glass ionomer, 9. Glass carbomer. The base materials in each group were applied to the cavity floor and restoration was completed using a nanohybrid composite resin and an universal adhesive system. To evaluate radiopacity, radiographic images were taken using direct digital system and mean gray values were measured with ImageJ software. To analyse microleakage, specimens were subjected to thermocycling, immersed in 2% methylene blue solution for 24 hours, sectioned buccolingually and leakage values observed on the half-piece surfaces were examined under a stereomicroscope and recorded. Data were analysed using One-way Analysis of Variance, Tukey HSD Test and Pearson Chi-Square with Bonferroni-corrected Z Test (p˂0.05). Results: In terms of radiopacity, while alkasite and low flowable composite showed the highest radiopacity, glass carbomer gave the lowest (p

The effect of nano propolis on surface color changes of nanohybrid composite resins

Background: Nanohybrid composite resins have many advantages, but one disadvantage is their absorbent nature which can lead to discoloration. Phenols and flavonoids in nano propolis cause diffusion and affect the matrix and pigments of nanohybrid composite resins. The accumulation of reduction-oxidation reactions causes new compounds of nanohybrid composite resins to occur so that they have different colors. Objective: The study was conducted to determine the changes in surface color of nanohybrid composite resin after immersion in nano propolis at 5% concentration. Methods: Research experimental laboratory method with pre and post test design was applied to 25 nanohybrid composite resin fruit samples of size (5x5x1.5) mm embedded in bovine incisive, then immersed in 5% nano propolis and 25 ml of distilled water at 37oC for five days. The color change (ΔE) was measured with a DSLR camera and processed with Adobe Lightroom Classic software in CIE L*a*b* format. Results: The anova test on ΔE in the data showed the p-value of sphericity assumed was smaller than 0.05. There is a difference in the average measurement results on the first day to the fifth day in the treatment group. Independent t-test of control and treatment data showed a significant difference in measurement results. The results of the post hoc test with the Tukey method showed that the treatment groups at 4x24 hours and 5x24 hours did not have significant differences. P-value at 4x24 hours and 5x24 hours was 0.957. Conclusion: There was a change in the surface color of the nanohybrid composite resin after being immersed in a nano-solution of propolis with a concentration of 5%.

An In Vitro Analysis of the Effects of Mouthwashes on the Surface Properties of Composite Resin Restorative Material.

Restorative composite resins have clinical prime importance in modern dental practice, but numerous factors influence their prognosis in the oral environment. Their interaction with oral care products, like mouthwashes, is one such factor. This study aimed to evaluate the quantifiable effects of different mouthwashes on the surface properties of the composite resin restorative material. The method involved formulating 90 samples of nanohybrid composite resins (Medicept Dental India Private Limited, Mumbai, India). The samples were treated with 1% alcohol, without alcohol, and with a saline solution (control). Surface roughness (Ra values) and microhardness had been checked before and after an exposure period of 24 hours. Data were thus tabulated, and from that, average values of surface roughness and microhardness were derived. This data was analyzed using the IBM SPSS Statistics for Windows, V. 26.0 (IBM Corp., Armonk, NY). Analysis of variance (ANOVA) and a t-test were used to compare the means of the variables. The level of significance was fixed at p < 0.05. The surface roughness value was significantly highest in the ethanol-containing mouthwash-treated samples after 24 hours of exposure (p < 0.05). The microhardness was statistically lower in these samples (p < 0.05). These research data give quantitative information, however, about the mass effect of mouthwashes on the composite resin restorative material. The presented changes, which were illustrated by the values of surface roughness and microhardness, are drawing attention to the fact that a cautious approach must be taken in the recommendations for oral care in the provision of intensive treatments with restorative composite resins.

Evaluation of Surface Roughness and Microhardness of Bulk-fill and Nanohybrid Composite after Exposure to Different Beverages at Various Time Intervals - An In vitro Study.

The aim of the study was to compare the surface roughness and microhardness of bulk-fill composite and nanohybrid composite resin after exposure to three different beverages at different time intervals. In this study, 60 composite discs each for bulk fill and nanohybrid, of dimensions 10 mm × 2 mm were made. Both composites were randomly divided into four subgroups, i.e., 15 samples each for artificial saliva, tea, coffee, and soft drinks which were further subdivided into five samples for three time intervals. Composite resin discs were immersed in beverages for 4 min in 24 h for 7, 15, and 30 days. All samples were evaluated for surface roughness and microhardness before and after immersion. Both the composites showed a significant increase in surface roughness in all the beverages with maximum change in surface roughness observed in nanohybrid composite resin immersed in soft drinks. Furthermore, the microhardness of both the composites was decreased significantly in all beverages with maximum change in microhardness observed in nanohybrid composite resin immersed in soft drinks. Bulk-fill composite resin has better resistance to surface roughness and higher microhardness as compared to nanohybrid. Furthermore, acidic beverages highly affect the physical properties of both composite resins for longer periods.

Effect of repeated preheating on color stability of three types of composite resins and a giomer: An in vitro study.

This study assessed the effect of repeated preheating of three types of composite resins and a giomer on their color stability. In this in vitro study, 128 composite resin and giomer specimens with a 10-mm diameter and a 2-mm height were evaluated in eight groups (n=16) of Heliomolar microfilled, Brilliant Enamel microhybrid, and Tetric N-Ceram nanohybrid composite resins, and Beautifil II giomer used at room temperature and also after preheating of the tube in a water bath at 55‒60 °C for 40 times. After preparing the specimens, their color parameters were measured by a spectrophotometer. The specimens were immersed in a tea solution for 3 hours/day for 40 days and underwent spectrophotometric color assessment again. The color change (∆E) was calculated and analyzed by two-way ANOVA (α=0.05). The effects of composite resin type (P<0.001) and preheating (P<0.001) and their interaction effect (P<0.001) were significant on ∆E. Immersion in a tea solution caused a significantly greater color change in giomer (P<0.05). The ∆E of the microfilled composite resin was significantly higher than that of nanohybrid (P=0.003) and microhybrid composite resin (P=0.004). Repeated preheating of giomer, microhybrid, and nanohybrid composite resin specimens to 55‒60 °C for 40 times adversely affected their color stability in the tea solution. The color change was significantly greater for giomer.

An influence of preheating composites on microleakage- An invitro study

Resin composites have become one of the widely used restorative materials in the field of dentistry. Resin composite Pre-heating is a recent innovative method that is clinically beneficial by improving handling and marginal adaptation of the resin to the tooth. The study aims to determine the effect of temperature on the degree of microleakage in resin composite restorations. In the present study, Class 1 cavity was prepared in 30 extracted non-carious human premolars and divided into two groups. Group A (n=15) - filled with nano-hybrid resin composite (3M™ Filtek™ Z350 XT Universal Composite) at room temperature. Group B (n=15) - filled with the same resin preheated and then checked for micro-leakage under SEM. Mann-Whitney test was used to compare the mean Marginal Leakage scores between the 2 groups. There was a statistically significant difference in the micro-leakage score between group A and group B. Group B showed minimal or no micro-leakage in comparison to Group A. Preheating the resin composite has better adaptability to the walls thus reducing micro-leakage and postoperative sensitivity.