Effects of nanohybrid flowable resin-based composites on fibroblast viability using different light-curing units.

PURPOSE: To investigate the in vitro cytotoxic effects of Bis-GMA-containing and Bis-GMA-free flowable resin-based composites (RBCs) on primary human gingival fibroblast cells (hGFc) using direct and indirect curing methods and three different light-curing units (LCUs). MATERIALS AND METHODS: Cells were isolated and cultured in vitro in 24-well plates. The plates were divided into treatment (cells with RBC), control (cells only), and blank (media only) groups. In the treatment groups, two types of nanohybrid flowable RBCs were used: Bis-GMA-free and Bis-GMA groups. Each treatment group was subdivided according to the curing method, i.e., direct curing (RBC was injected into the wells and cured directly on the attached cells) and indirect curing (the samples were pre-cured outside of the well plate and then added to the well plate with cells). To vary the LCU, the subgroups were further divided into three groups: multiple-emission peak light-emitting diode, single-emission peak light-emitting diode, and quartz-tungsten-halogen units. Curing was conducted for 20 seconds. The hGFc cytotoxicity was evaluated via 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay after 24, 48, and 72 hours of culturing. RESULTS: The MTT assay results showed that both RBCs were significantly cytotoxic toward hGFc compared to the control group (p < 0.0001). The Bis-GMA group was significantly more cytotoxic to the cells compared to the Bis-GMA-free group. In addition, the curing method and time interval affected cell viability regardless of the LCU used. CONCLUSION: The Bis-GMA flowable RBC and direct curing method had the highest cytotoxic effects on hGFc regardless of the LCU used. Careful selection of flowable RBCs and proper curing techniques are required to decrease the cytotoxic effects on hGFc and improve the clinical handling of oral tissues.

Assessment of the Satisfaction of Patients Treated by Undergraduate Dental Students at a Saudi Government University: A Cross Sectional Study.

Purpose: The long-term success of any organization is highly dependent on client satisfaction. This applies to the medical and dental fields, where patient satisfaction is considered an indirect indicator of the quality of service provided. This study aimed to assess the level of satisfaction of patients treated by final-year undergraduate students at King Abdulaziz University Dental Hospital (KAUDH). Patients and Methods: In this cross-sectional study, an online questionnaire was distributed to patients (aged ≥14 years) treated at KAUDH by sixth year students during the academic year 2020/2021. The questionnaire comprised 36 items, including demographic and general data, type of dental problems, type of dental treatment received, and satisfaction assessment based on the Dental Satisfaction Questionnaire. Data were analyzed using one-way ANOVA and independent sample t-tests (α=0.05). Results: A total of 203 responses were received (58% response rate). The reliability of the satisfaction tool (Cronbach's alpha) was 0.88, indicating a high reliability. The overall satisfaction level was 80.1% (±14.2). The satisfaction levels related to pain management, quality of care, and access to care were 76.4% (±19.9), 86.2% (±17.1), and 77.5% (±16.5) respectively. The highest satisfaction level (91.5%) was related to the quality item "The student was always treating me with respect". Age, number of visits, length of treatment, case severity, and treatment complexity were not significantly correlated with patient satisfaction (p ≥ 0.116). New patients who had their files directly opened by a sixth-year student and were treated immediately were more satisfied than patients who already had files at KAUDH and were referred to sixth-year students for treatment (p=0.029). Conclusion: Patients treated by final-year students at KAUDH showed high satisfaction levels in relation to pain management, treatment quality, and access. However, the satisfaction of existing old patients was lower than that of new patients, which warrants further assessment, particularly regarding the hospital referral system.

Sagittal condylar angle and gender differences.

PURPOSE: The purpose of this study was to measure sagittal condylar inclination (SCI) in male and female participants and to assess differences between the two groups. This measurement has a clinical value in setting the articulator SCI before fabrication of indirect restorations. MATERIALS AND METHODS: The study included 32 dental students, 16 men and 16 women (aged 18 to 40 years). The participants had no signs of muscular or articular pain. SCI was recorded for participants using a CADIAX® compact 2 electronic axiograph. RESULTS: The mean SCI in both men and women varied between 26.1° and 61.8°, with a mean of 41.9° (SD 7.8). The mean right SCI was 42.0° (SD 8.5), and the mean left SCI was 41.9° (SD 9.2). The mean SCI for men was 40.3° (SD 7.9), and the mean for women was 43.6° (SD 7.7). No statistically significant difference in SCI values was found between the right and left side (p = 0.995), or between the male and female groups (p = 0.133). Also, no correlation could be found between SCI and the age of the participants (r(2) = 0.016, p = 0.489). CONCLUSIONS: The mean value of SCI was within the range reported in previous studies. SCI is highly variable, but this variability does not seem to be attributed to condylar asymmetry, gender, or age of the adult participants. This high variability suggests that independent condylar measurements should be conducted for each patient instead of relying on reported average values.

The effect of bleaching on surface roughness and gloss of different CAD/CAM ceramic and hybrid ceramic materials.

OBJECTIVE: To assess the effect of bleaching on surface roughness and gloss of different CAD/CAM ceramic materials. METHODS: The ceramic materials included IPS e.max CAD (lithium disilicate), VITA ENAMIC (polymer infiltrated ceramic), and Celtra Duo CAD (zirconia reinforced lithium silicate). Samples of each material were randomly divided into four groups (n = 10); a control group immersed in distilled water, the second and third groups were treated with 20% carbamide peroxide (20% CP) and 35% carbamide peroxide (35% CP) bleaching agents for 4 h/day and 60 min/day respectively for 7 days. The fourth group was treated with 40% hydrogen peroxide (40% HP) applied twice, each turn for 20 min. After treatment, the surface roughness (using 3D non-contact profilometry) and surface gloss were assessed followed by imaging with a scanning electron microscope. The data were analyzed using multiple linear regression and Kruskal-Wallis one-way ANOVA tests (α = 0.05). RESULTS: The surface roughness (p = 0.157) and gloss (p = 0.073) of IPS e.max CAD were not significantly affected by the different bleaching treatments. Similarly, no significant effect on surface roughness (p = 0.162) and gloss (p = 0.965) were shown for Celtra Duo CAD. On the other hand, VITA ENAMIC was significantly affected when treated with 20% CP and 35% CP showing increased roughness (p = 0.001) and gloss (p = 0.008). CONCLUSIONS: Home bleaching treatments (20% CP and 35% CP) significantly affected the surface roughness and gloss of VITA ENAMIC while IPS e.max CAD and Celtra Duo CAD were not affected by the different bleaching treatments.

The Effect of Home and In-Office Bleaching on Microhardness and Color of Different CAD/CAM Ceramic Materials.

The aim of this study is to assess the effect of different bleaching agents on microhardness and color of CAD/CAM ceramics including IPS e.max CAD (lithium disilicate), VITA ENAMIC (polymer-infiltrated ceramic), and Celtra Duo CAD (zirconia-reinforced lithium silicate). Materials' samples were divided into three groups (n = 10) and each received a different bleaching treatment; 20% carbamide peroxide, 35% carbamide peroxide, and 40% hydrogen peroxide. A fourth group was stored in water acting as a control. Vickers microhardness and spectrophotometric color measurements were taken at baseline and after bleaching. IPS e.max CAD showed a significant reduction (about 14%), while VITA ENAMIC showed a significant increase (about 78%) in microhardness after bleaching (p ˂ 0.001). Celtra Duo CAD did not demonstrate a significant change in microhardness (p ≥ 0.609). The color difference (ΔEab) after bleaching was 0.29 (±0.08), 2.84 (±0.64), and 1.99 (±0.37) for IPS e.max CAD, VITA ENAMIC, and Celtra Duo CAD, respectively. It could be concluded that the effect of bleaching on color and microhardness was mainly material-dependent. Bleaching significantly affected the microhardness of IPS e.max CAD and VITA ENAMIC. The color difference was within the clinically imperceptible range for IPS e.max CAD, while VITA ENAMIC and Celtra Duo CAD demonstrated perceptible color change.

A simulation model used in teaching denture border adjustment: Randomized controlled trial.

OBJECTIVES: The goal was to propose a new simulation model as a training tool in complete denture (CD) flange adjustment and to evaluate if the model can improve student competencies in different learning domains. METHODS: Fourth-year undergraduate dental students (n = 100) were equally divided into control and test groups. Both groups received didactic instructions for CD post-insertion procedures, but the test group had additional simulation training using modified working casts. Both groups then performed CD flange adjustment on real patients, and their skills were evaluated using a specific checklist. The data were assessed by independent samples t-test and a chi-square test at α = 0.05. RESULTS: The students in the test group showed significantly better overall performance (57.94%) compared with the control group (30.14%) in clinical post-insertion CD flange adjustment procedures (p < 0.001). However, the psychomotor skills of the male students in the test group were not significantly influenced (p = 0.268). Considering the competencies for different tasks, more students that were competent were present in the test group compared to those in the control group regarding most of the knowledge (p ≤ 0.012) and all of the cognitive skill tasks (p ≤ 0.021). More students were competent for half of the psychomotor skill tasks (p ≤ 0.027). However, when considering gender, the number of competent male students was significantly greater in the test group only for one of the psychomotor tasks. CONCLUSION: The simulation model significantly improved the overall clinical skills of the students, allowing them to learn the common CD post-insertion maintenance procedures before performing the procedure clinically.

The Effect of Simulated Chewing on the Surface Roughness of Direct and Indirect Resin-Composites Opposed by Zirconia: An In Vitro Study.

Purpose: To assess the surface roughness of two different light-cured resin-composites when opposed by monolithic zirconia after simulated mastication. Materials and Methods: Materials included a direct restorative nanohybrid (n = 10) and an indirect microhybrid (n = 10) resin-composite (Tetric EvoCeram and Sinfony, respectively). The antagonist material was 3 mol% yttria-stabilized tetragonal zirconia polycrystalline ceramic. Each material was subjected to in vitro chewing against zirconia using a chewing simulator for 250,000 cycles. A 3D profilometer was used to assess the surface roughness parameters of each resin-composite before and after the simulated chewing. Independent t-test and paired sample t-test were performed to compare roughness values for both materials and to compare baseline and after chewing simulation values (p = 0.05). Results: Sinfony showed significantly greater roughness values compared to Tetric EvoCeram (p ≤ 0.025) before and after simulated chewing, except for Sa and Sv parameters after simulated chewing where the difference between the two materials was insignificant (p = 0.06 and 0.89, respectively). Surface roughness increased for both materials after simulated chewing compared to baseline values, but the difference was insignificant (p ≥ 0.065). However, Sa (p = 0.04) and Sv (p = 0.012) for Tetric EvoCeram were significantly higher after compared to before chewing simulation. Conclusion: Tetric EvoCeram had a smoother surface than Sinfony before and after simulated chewing. Surface roughness for both materials was higher after simulated chewing compared to baseline values which represent surface damage that was significant for Tetric EvoCeram while Sinfony showed better resistance.

Repair of temporary fixed dental prostheses using a flowable resin composite: Effect of material, bonding, and aging.

OBJECTIVES: Assessment of the effect of aging and bonding on the reparability of different temporary crown and bridge materials using a flowable resin composite. METHODS: The materials used included two bis-acryl and two polymethylmethacrylate materials. The materials were aged either dry, in distilled water, or in a 75% ethanol/water solution. Each group was divided into three subgroups (n = 6) according to the bonding method: application of a universal adhesive, application of a universal primer followed by a universal adhesive, or no bonding. Materials were repaired with a light-cure flowable resin composite; then, they were subjected to thermocycling and tested by shear bond strength. The data were analysed using three-way ANOVA, one-way ANOVA, and Tukey post hoc tests (α = 0.05). RESULTS: The shear bond strength was significantly higher for bis-acryl compared to polymethylmethacrylate materials (p < 0.001). In terms of aging conditions, shear bond strength was in the order of 75% ethanol/water solution < dry < water. The application of bonding agents significantly increased the shear bond strength of polymethylmethacrylate-based materials (p < 0.001). The difference between water and dry storage was insignificant (p = 0.558); however, storage in a 75% ethanol/water solution showed significantly lower values compared to both dry and water storage in most of experimental groups (p < 0.001). Polymethylmethacrylate-based materials mainly demonstrated adhesive failure, while bis-acryl materials predominantly showed cohesive failure. CONCLUSION: The bond strength of a light-cure flowable resin composite is significantly higher with bis-acryl compared to that with polymethylmethacrylate-based substrates. Aging in water does not have a significant effect; however, the 75% ethanol/water solution tends to negatively affect repairability. The application of different bonding agents positively affects the repair strength, especially for polymethylmethacrylate-based substrates.

Dentists' Knowledge, Attitudes, and Awareness of Infection Control Measures during COVID-19 Outbreak: A Cross-Sectional Study in Saudi Arabia.

As antiviral vaccines are still pending for the COVID-19 disease, improving dentists' knowledge and prevention measures is important. This study aimed to assess dentists' knowledge, attitude, and perception of COVID-19 in Saudi Arabia during the early outbreak period. In addition, infection control measures for dental setting were also assessed. Online questionnaire was distributed to dentists in different regions of Saudi Arabia when COVID-19 outbreak in Saudi Arabia was at its beginning. The questionnaire was assessing demographic variables, knowledge, attitude, risk perception, and preparedness towards COVID-19. Questions regarding infection control measures were also included. The correct incubation period of the virus was recognized by 43% of participants. Fever, cough, and shortness of breath were the mostly recognized symptoms for COVID-19 (98.9%, 95.5%, and 93.3% respectively). Participants in age groups ≥60, 50-59, and 20-29 years old were more likely to perceive COVID-19 as a very dangerous disease compared to 30-39 and 40-49 age groups. Dentists in Saudi Arabia showed satisfactory knowledge and positive attitude towards COVID-19. Improving dentists' level of knowledge could be achieved through increasing their accessibility to materials provided by dental health care authorities, which specifies the best and safest approaches for dealing with patients during and after the outbreak.

Knowledge, Attitude, Behavior, and Stress Related to COVID-19 among Undergraduate Health Care Students in Jordan.

OBJECTIVES: This study aimed to assess knowledge, attitude, and infection control measures related to the coronavirus disease 2019 (COVID-19) pandemic outbreak among Jordanian health care students. Besides, their social behavior and stress level regarding COVID-19 infection were assessed. MATERIALS AND METHODS: An online questionnaire was distributed to medical, dental, pharmacy, nursing, and applied health science students in Jordan during the COVID-19 outbreak quarantine in March 2020. The questionnaire comprised 38 questions assessing demographic data, knowledge, attitude, risk perception, and stress level toward COVID-19. Questions regarding infection control measures and social behavior after the quarantine were also included. STATISTICAL ANALYSIS: Independent samples t-test, one-way analysis of variance (ANOVA), and chi-square at a significance level of 5% were used for data analysis. RESULTS: A total number of 935 responses were collected. The knowledge score of 55.72% of participants was satisfactory and it was higher for the clinical years' students compared with the basic years' students (p = 0.000) (descending order: sixth year > fifth year > fourth year > third year > first year > second year). Also, knowledge scores were significantly higher for medical and dental students than other disciplines (descending order: medicine, dentistry, pharmacy, nursing/applied) (p = 0.000). The social media (89.1%) and TV or radio (69.5%) were mainly routes through which participants heard about COVID-19. Moderate and justifiable feelings about COVID-19 were found in the majority of the participants. CONCLUSION: Although the majority of students showed good knowledge scores, few of them appeared to have a serious lack of knowledge. Therefore, proper education and mentoring are necessary for students before reopening the university campuses.

The effect of desiccation on water sorption, solubility and hygroscopic volumetric expansion of dentine replacement materials.

OBJECTIVE: To evaluate water sorption, solubility and hygroscopic expansion and the effect of desiccation for a calcium silicate-based material, a conventional glass ionomer, and a resin-modified glass ionomer. METHODS: Water sorption, solubility and hygroscopic expansion of Biodentine™ (BD), GC Fuji IX GP® FAST (FJ), and Ionolux (IO) were tested under two pre-storage conditions: with desiccation and without desiccation. Disc-shaped samples (n=5) were immersed in water and weighed at different time intervals (1h, 24h, 3d, 7d and 30d) and hygroscopic expansion was recorded at 7d and 30d. Data were analysed using Factorial repeated measures ANOVA, one-way/two-way ANOVA, Independent samples t-test and Tukey's post hoc test (α=0.05). RESULTS: With desiccation, sorption of IO and FJ was 124.33µg/mm3 and 79.97µg/mm3 respectively. Solubility was -12.36µg/mm3 for IO and -20.19µg/mm3 for FJ. Hygroscopic expansion was 3.01% for IO and -2.35% for FJ. Without desiccation, sorption was in the order: IO˃BD˃FJ (130.35µg/mm3, 122.07µg/mm3, and 107.21µg/mm3 respectively), while solubility order was: BD˃FJ˃IO (154.83µg/mm3, 88.82µg/mm3, and 25.67µg/mm3 respectively). IO and FJ showed significant difference in sorption and solubility between the two pre-storage treatment groups (p˂0.005). Hygroscopic expansion was in the order: IO˃BD˃FJ. SIGNIFICANCE: BD had the highest solubility while IO had the least. The relatively stable polymeric resin in IO may contribute to its low solubility but high hygroscopic expansion. Desiccation had significant effect on sorption, solubility and volumetric expansion of water-based materials.

Post-irradiation hardness development, chemical softening, and thermal stability of bulk-fill and conventional resin-composites.

OBJECTIVES: To measure bottom/top hardness ratio of bulk-fill and conventional resin-composite materials, and to assess hardness changes after dry and ethanol storage. Filler content and kinetics of thermal decomposition were also tested using thermogravimetric analysis (TGA). METHODS: Six bulk-fill (SureFil SDR, Venus bulk fill, X-tra base, Filtek bulk fill flowable, Sonic fill, and Tetric EvoCeram bulk-fill) and eight conventional resin-composite materials (Grandioso flow, Venus Diamond flow, X-flow, Filtek Supreme Ultra Flowable, Grandioso, Venus Diamond, TPH Spectrum, and Filtek Z250) were tested (n=5). Initial and 24h (post-cure dry storage) top and bottom microhardness values were measured. Microhardness was re-measured after the samples were stored in 75% ethanol/water solution. Thermal decomposition and filler content were assessed by TGA. Results were analysed using one-way ANOVA and paired sample t-test (α=0.05). RESULTS: All materials showed significant increase of microhardness after 24h of dry storage which ranged from 100.1% to 9.1%. Bottom/top microhardness ratio >0.9 was exhibited by all materials. All materials showed significant decrease of microhardness after 24h of storage in 75% ethanol/water which ranged from 14.5% to 74.2%. The extent of post-irradiation hardness development was positively correlated to the extent of ethanol softening (R(2)=0.89, p<0.001). Initial thermal decomposition temperature assessed by TGA was variable and was correlated to ethanol softening. CONCLUSIONS: Bulk-fill resin-composites exhibit comparable bottom/top hardness ratio to conventional materials at recommended manufacturer thickness. Hardness was affected to a variable extent by storage with variable inorganic filler content and initial thermal decomposition shown by TGA. CLINICAL SIGNIFICANCE: The manufacturer recommended depth of cure of bulk-fill resin-composites can be reached based on the microhardness method. Characterization of the primary polymer network of a resin-composite material should be considered when evaluating its stability in the aqueous oral environment.

Long-term sorption and solubility of bulk-fill and conventional resin-composites in water and artificial saliva.

OBJECTIVES: To assess sorption and solubility of several bulk-fill and conventional resin-composites after one-year storage in water and artificial saliva (AS). METHODS: Six bulk-fill (SureFil SDR, Venus Bulk Fill, X-tra base, Filtek Bulk Fill flowable, Sonic Fill, and Tetric EvoCeram Bulk Fill) and eight conventional resin-composites (Grandioso Flow, Venus Diamond Flow, XFlow, Filtek Supreme XTE, Grandioso, Venus Diamond, TPH Spectrum, and Filtek Z250) were tested. Disc shaped samples (n=5) were randomly immersed into distilled water and AS for one-year period and weighed at different time intervals. Data were analysed using repeated measures ANOVA, one-way ANOVA, and Tukey's post hoc test (α=0.05). RESULTS: In water, all materials (with the exception of X-Flow) reached a stable mass within three months with a slow increase observed in AS up to one year. Sorption values in water and AS for most materials were not significantly different (p≥0.2). Sorption and solubility values in water ranged from (6.5 µg/mm(3) and -1.77 µg/mm(3) respectively) for X-tra base to (78.8 µg/mm(3) and 44.77 µg/mm(3) respectively) for X-Flow (p<0.005). Sorption of the polymer matrix in water ranged from 1.18% for XB to 9.95 % for XF. CONCLUSIONS: Water sorption and solubility of resin-composites are material-dependent and highly affected by the filler loading and hydrophilicity of the resin matrix. BisEMA and UDMA-BisEMA based resins appeared to be more hydrophobic than BisGMA based systems. Water and AS, are generally comparable as storage media in terms of water sorption. CLINICAL SIGNIFICANCE: Bulk-fill materials and conventional resin-composites tested varied in terms of sorption and solubility but both were considered stable in longterm water storage. The composition of each material is critical and can affect the long-term clinical performance of either type of resincomposites.

Qualitative and quantitative characterization of monomers of uncured bulk-fill and conventional resin-composites using liquid chromatography/mass spectrometry.

OBJECTIVES: The aim of this study was to assess the resin matrix monomer composition of selected bulk-fill and conventional resin-composite materials using reverse phase liquid chromatography coupled with electron spray ionization mass spectrometry. MATERIAL AND METHODS: Six bulk-fill (SureFil SDR, Venus Bulk Fill, X-tra base, Filtek Bulk Fill flowable, Sonic Fill, and Tetric EvoCeram Bulk Fill) and eight conventional resin-composites (Grandioso Flow, Venus Diamond Flow, X-Flow, Filtek Supreme XTE, Grandioso, Venus Diamond, TPH Spectrum, and Filtek Z250) were tested. For assessment of resin composition and relative monomer amounts, uncured resin-composites were analysed with reverse phase liquid chromatography/electron spray ionization mass spectrometry. logP values (a measure of hydrophobicity) of detected compounds were calculated and their correlation to reverse phase liquid chromatography retention time was explored. Data were analysed with one-way ANOVA, Tukey post hoc test, Pearson correlation and regression analyses at α=0.05. RESULTS: The main monomers detected were BisGMA, UDMA, TEGDMA, and BisEMA. Monomers were detected at variable combinations in different materials with significantly different relative amounts. Other monomers were detected including HDDMA, DEGDMA, TCD-DI-HEA, and SDR-UDMA in Grandioso flow, X-flow, Venus Diamond, and SureFil SDR respectively. A positive correlation between logP and reverse phase liquid chromatography retention time was detected (r(2)=0.62, p=0.004). CONCLUSIONS: Resin composition of bulk-fill resin-composites is comparable to that of conventional materials with the exception of SureFil SDR. The relative hydrophobicity of dental monomers can be determined by their reverse phase liquid chromatography retention time.

Analysis of long-term monomer elution from bulk-fill and conventional resin-composites using high performance liquid chromatography.

OBJECTIVE: The aim of this study was to assess monomer elution from bulk-fill and conventional resin-composites stored in different media using high performance liquid chromatography (HPLC) for up to 3 months. METHODS: Six bulk-fill (SureFil SDR, Venus Bulk Fill, X-tra base, Filtek Bulk Fill flowable, Sonic Fill, and Tetric EvoCeram Bulk Fill) and eight conventional resin-composites (Grandioso Flow, Venus Diamond Flow, X-Flow, Filtek Supreme XTE, Grandioso, Venus Diamond, TPH Spectrum, and Filtek Z250) were tested. Cylindrical samples (n=5) were immersed in water, 70% ethanol/water solution (70% E/W), and artificial saliva and stored at 37°C for 24h, 1 month, and 3 months. The storage solutions were analysed with HPLC. Data were analysed with repeated measures ANOVA, one-way ANOVA, and Tukey post hoc test at α=0.05. RESULTS: Monomers detected in water and artificial saliva were TEGDMA, DEGDMA, UDMA, and TCD-DI-HEA. No eluted monomers were detected from X-tra base and Sonic fill in these media. All monomers showed a variable extent of elution into 70% E/W with significantly higher amounts than those detected in water and artificial saliva. Significantly higher elution was detected from UDMA-BisEMA based composites compared to BisGMA and BisGMA-BisEMA based systems in 70% E/W. The rate of elution into different media varied between different monomers and was highly dependent on the molecular weight of the eluted compounds. SIGNIFICANCE: Elution from bulk-fill resin-composites is comparable to that of conventional materials despite their increased increment thickness. Monomer elution is highly dependent on the hydrophobicity of the base monomers and the final network characteristics of the resin-matrix.

Degree of conversion of bulk-fill compared to conventional resin-composites at two time intervals.

OBJECTIVE: The purpose of this study was to assess the degree of conversion (DC) over time, using FTIR spectroscopy for bulk-fill flowable resin composite materials compared to conventional flowable and regular resin composite materials. METHODS: Eight resin composites were investigated including flowable bulk-fill materials SureFil SDR (SDR), Venus bulk-fill (VBF), x-tra base (XB), and Filtek Bulk Fill (FBF). Conventional flowable and regular composite materials included: Venus Diamond flow (VDF), Grandioso flow (GRF), Venus Diamond (VD), and Grandioso (GR). Degree of conversion (DC) was assessed by Fourier transform infrared spectroscopy using attenuated total reflectance technique. DC was measured for samples immediately post-cure (n=3), and after 24h storage period at 37°C (n=3). Results were analysed using one-way analysis of variance (ANOVA), Bonferroni post hoc test, and independent-samples t-test at α=0.05 significance level. RESULTS: Immediately post-cure, the mean DC values of the different materials were in the following order: GRF>VDF>SDR>VBF>XB>GR>FBFVBF>VD>SDR>VDF>GR>XB