Composite Resin Surfaces Research Articles

The effect of soaking blimbi (Averrhoa blimbi, L) fruit extract on the roughness of nanofiller composite resin

Background Nanofiller composite resin is a restorative material or filling material that is activated by visible light to restore anterior and posterior teeth. One of the characteristics of the composite resin surface is surface roughness. Surface roughness is greatly influenced by acidic solutions, namely the acid in drinks. Objective: To determine the effect of soaking blimbi fruit extract (Averrhoa blimbi L.) on the roughness of nanofiller composite resin. Research Method: This research uses laboratory experimental research. The sampling method used 6 sample groups in each group, consisting of 4 groups, namely 2 treatment groups and 2 control groups. The treatment group consisted of 50% and 100% blimbi fruit extract, then the control group consisted of a positive control grup (citric acid) and a negative control (aquadest). Then a surface roughness test was carried out on each group using a Surface Roughness Tester tool, then the test data was analyzed using the One-Way Anova test with the condition that the data had to be normal and homogeneous, the condition for the One-Way Anova test was that the sig value Sig <0.05. Results: Based on analysis using One-Way Anova, the sig 0.518 (p>0.05), which means there are no significant differences in each sample group. Conclusion: There is no influence on the roughness of the nanofiller composite resin by soaking in star fruit extract (Averrhoa blimbi, L) because the value difference is not significant.

The effect of different treatment protocols on shear bond strength in resin composite restoration repair

BackgroundIt was aimed to investigate the effect of sandblasting and laser surface treatment on shear bond strength in composite restoration repair in vitro.MethodsA micro-hybrid composite (Filtek Z250, 3 M-ESPE, USA) was used to prepare 120 samples. The samples were subjected to a thermal cycle test 5,000 times between 5 and 55 0C, and they were randomly divided into 12 groups (n = 10). No surface treatment was performed in Groups 1 to 4, which were designed as control groups. The surfaces of the samples in Groups 5 to 8 were sandblasted with a Cojet device, and the surfaces of the samples in Groups 9 to 12 were applied Er, Cr: YSGG laser. After the sample surfaces were divided into groups with and without acid etching, universal adhesive was applied, and the repair process was performed using Filtek Z250 or nano-filled resin composite (Filtek Ultimate, 3 M-ESPE, USA). The thermal cycle test was repeated 5,000 times between 5 and 55 0C on all repaired samples. The repair shear bond strength of the samples was measured using a universal testing device (Shimadzu IG-IS, Kyoto, Japan). The fracture types were evaluated by optical microscopy and scanning electron microscopy (SEM). Statistical analyses of the findings were evaluated by the Kruskal Wallis test and Mann Whitney U test at 0.05 significance degree.ResultsThe highest mean shear bond strength values were obtained from the samples sandblasted with CoJet, followed by Er, Cr: YSGG laser, and the control group. It was determined that there was a significant difference between the mean shear bond strength values obtained from the control group and the other surface treatment groups (p < 0.05). In general, significantly higher mean shear bond strength values were obtained when the universal adhesive was applied in total-etch mode compared to the application in self-etch mode (p < 0.05). Additionally, it was determined that higher shear bond strength values were obtained with Filtek Ultimate compared to Filtek Z250 (p < 0.05).ConclusionWithin the limitations of this study, it can be concluded that the use of universal adhesive in total-etch mode, in addition to surface treatments on the resin composite surface in the repair protocol and the use of nano-filled resin composite as repair material can increase the mean shear bond values in repair.

In Vitro Effects of Sof-Lex, Eve, and Astropol Polishing Systems on Composite Resin Surface Roughness After Aging

Objectives: Surface roughness is one of the important properties of composite restorations. Different polishing systems are used to provide an appropriate composite restoration surface. The aim of this study was to evaluate the effects of Sof-Lex, Eve, and Astropol polishing systems on composite resin surface roughness after aging. Materials and Methods: In this in vitro study, 36 composite discs (8×2mm) were fabricated. The specimens were randomly divided into three groups (N=12) for polishing with (I) Sof-Lex (3M ESPE), (II) Eve (Ernst Vetter GmbH), and (III) Astropol (Ivoclar/Vivadent) polishing systems. The specimens were then subjected to thermocycling. Surface roughness of the specimens was measured before and after polishing, and after thermocycling by a contact profilometer. Repeated Measures ANOVA was used to analyze the data (α=0.05). Results: Although Astropol showed slightly higher surface roughness in comparison to Sof-Lex and Eve, the level of surface roughness before and after polishing and after aging was not significantly different among the three polishing systems (P=0.704). Conclusion: Within the limitations of this in vitro study, Sof-Lex, Eve, and Astropol showed similar acceptable results with regard to composite resin surface roughness.

An in vitro assessment of the influence of dentinal pretreatment with chlorhexidine, nonthermal atmospheric plasma, chitosan, and proanthocyanidins on shear bond strength to composite.

Dentin biomodification has been emphasized as a means of improving the bond between composite resin and tooth surface, consequently enhancing its longevity. To evaluate the shear bond strength (SBS) of dentin after pretreatment with 2% chlorhexidine (CHX), 2% chitosan, nonthermal atmospheric plasma (NTAP), proanthocyanidins (5% pine bark ((PB) and 5% bromelain). The study was designed as an in vitro investigation. Sixty extracted mandibular molars (n = 60) were gathered for this in vitro research. The teeth were decoronated to expose the dentinal surface. All samples have been etched with 37% phosphoric acid and then pretreated with respective dentin biomodifiers. Group I (control): No pretreatment was done, Group II: 2% CHX, Group III: NTAP, Group IV: 5% PB, Group V: 2% chitosan, Group VI: 5% bromelain. Specimens were evaluated for the SBS test, which was done under the instron universal machine at a speed of 1 mm/min after a bonding agent and composite build-up were applied. While Group I had the lowest SBS (10.391.59Mpa), Group V had the highest SBS (30.111.53 Mpa). Pretreatment of the dentin enhanced the SBS of dentin to composite. When utilized after etching, dentin biomodification increased all experimental group's bond strength in contrast to the control. The highest SBS values were recorded with 2% chitosan, followed by NTAP.

Water Sorption and Solubility of Highly Aesthetic Single-Shade Nano-Hybrid Resin Composites.

Background A single-shade resin composite is a new type of resin composite that was introduced in 2019. There is not much data regarding the water sorption (Wsp) and water solubility (Wsl) of this type of resin composite. Therefore, this study aimed to investigate Wsp and Wsl and their effects on the surface roughness of a single-shade nano-hybrid resin composite in comparison with a conventional nano-hybrid resin composite in accordance with ISO 4049:2019 (Dentistry - Polymer-based Restorative Materials). Material and methods An in vitro study was performed to investigate the Wsp and Wsl of a single-shade supra-nano-hybrid composite (Omnichroma) and a conventional nano-hybrid composite (Filtek™ Z250 XT) in accordance with ISO 4049:2019. Five disks were prepared of each material with dimensions of 15 ± 1 mm in diameter and 1 ± 0.1 mm in thickness, as per ISO 4049:2019. The results were calculated according to the ISO equations for Wsp and Wsl in µg/mm3. Atomic force microscopy (AFM) was used to analyze the surface roughness (Ra) of test specimens. Results The findings showed that the values of Wsl and Wsp of both materials are comparable and revealed no statistically significant difference (P > 0.05). The AFM images showed a higher Ra post-solubility testing, and the statistical analysis indicated a significant difference for both materials. Conclusions The study concluded that the single-shade resin composite (Omnichroma) and the conventional nano-hybrid composite (Filtek™ Z250 XT) are following the requirements of ISO 4049:2019. The AFM analysis indicated that resin composite surfaces are significantly affected when exposed to water for a prolonged period of time. However, the Ra variations of Filtek™ Z250 XT were higher than Omnichroma specimens. These results indicate that resin composite surfaces can be significantly impacted by prolonged water exposure. This knowledge is critical for enhancing the long-term clinical performance and durability of these dental restorative materials.

Comparative Evaluation of Surface Roughness and Color Stability Between Single-Shade Composite and Multi-Shade Composite: An In Vitro Study.

Introduction Composite resin materials are a popular choice for direct tooth-colored restorative purposes due to their excellent aesthetic qualities and versatility. The key determinants that impact the visual aspect of the restoration are gloss, surface roughness, and color stability. Research indicates that there is a direct correlation between the level of roughness on a composite resin surface and the likelihood of discoloration. The aim of this study was to compare and evaluate the surface roughness and color stability of a single-shade and multi-shade composite resin after subjecting it to toothbrush simulation and immersion in coffee and an aerated drink. Materials and methods Ten single-shade composite resinsand 10 multi-shade composite resins were packed into a Teflon mold and light cured. Pre-operative surface roughness values were evaluated using a surface profilometer. Toothbrush abrasion was simulated using a toothbrushing simulator. All these resin molds were then evaluated for initial color using a spectrophotometer machine (Konica Minolta, Japan). Five resin molds were then immersed in a beaker containing coffee for seven days and five resin molds were immersed into a beaker containing an aerated drink for seven days. Following this, the resin molds were re-evaluated for color stability using a spectrophotometer machine. Results The results of this study show that single-shade composite showed increased discoloration when compared with multi-shade composite resin. Also, there is a statistical difference between the single-shade composite and multi-shade composite when it comes to surface roughness and discoloration. Conclusion With the limitations of the present study, it can be concluded that single-shade composite resins have more discoloration potential in beverages than multi-shade composite resins.

The Effect of Mechanical Alteration on Repair Bond Strength of S-PRG-Filler-Based Resin Composite Materials.

This study investigates the impact of mechanical alteration on resin composite surfaces and its subsequent effect on repair bond strength. A total of 100 resin composite disks were prepared and were allocated for 24 h or 1 year of artificial aging. Specimens were embedded in epoxy resin, and the composite surfaces were mechanically altered using either diamond burs or air abrasion with aluminum oxide or glass beads. A universal bonding material was applied and a 2 mm circular and 3 mm high repair composite cylinder were prepared using a Teflon mold. Then, the specimens were tested for their shear bond strength, and the de-bonded specimens were observed under a scanning electron microscope to determine the failure pattern. SPSS 26.0 statistical software was used to analyze the data. Two-way ANOVA showed a statistically significant effect of mechanical alteration and aging on the shear bond strength of S-PRG-filler-based resin composite (p < 0.05). Surface modification with a fine diamond bur showed a significantly higher bond strength in both 24-h- and 1-year-aged specimens. Surface modification with alumina significantly increased the bond strength of 1-year-aged specimens; however, it was statistically insignificant for 24 h-aged specimens. Mechanical alteration with a fine diamond bur and 50-micron alumina can improve the repair bond strength of the composite.

The effect of beverage temperature on the surface roughness, microhardness, and color stability of the monoshade composite resin: An in vitro study

ObjectiveThis study assessed the impact of beverage temperature on the surface roughness, microhardness, and color stability of monoshade composite resin. Materials and MethodsA batch of 70 monoshade composite resin specimens manufactured by Charisma Diamond ONE (Kulzer, Hanau, Germany) was prepared. Initial readings for surface roughness, microhardness, and color were recorded. The specimens were then divided into seven groupings of ten each: Distilled water (control group), Nescafe coffee at 70 °C and 5 °C, Arabic coffee at 70 °C and 37 °C, and cola at 7 °C and 24 °C. These samples underwent 30-min daily immersion in their respective beverages for a duration of 30 days. Final measurements were then taken. A non-contact profilometer was used for measuring surface roughness, a Vickers microhardness machine from Contour GT-I (Bruker Nano GmbH, Berlin, Germany) for microhardness, and a Color-Eye 7000A Spectrophotometer (X-Rite, GretagMacbeth, Michigan USA) for color stability. Statistical analyses, including repeated measure ANOVA for microhardness, roughness, and color, were executed using SPSS version 23. ResultsAll beverages led to changes in composite color and properties. Notably, coffee at 70 °C resulted in significant discoloration of the composite resin surface (p < 0.0001). The beverage that most affected the surface hardness and roughness of the monoshade composite resin was cola at 7 °C (p = 0.008) ConclusionThe inherent chemicals in beverages, coupled with their temperatures, can influence the composite properties of resin, specifically surface discoloration, hardness, and roughness. Clinicians may, therefore, consider instructing patients about the potential negative effects of these beverages.

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

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). 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. The used materials showed statistically significant differences in microhardness and marginal adaptation. 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. 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.

The Effect of Positioning Guide Color on Shade Measurements Using a Clinical Spectrophotometer.

The purpose of this study was to investigate the influence of the color of positioning guides on the CIEL*a*b* color coordinates of ceramic, resin composite and bovine tooth surfaces measured by a clinical spectrophotometer. Positioning guides (n=10) in different colors (translucent, purple, yellow, green and, blue) were made for each surface (ceramic, resin composite and bovine tooth). The CIEL*a*b* color coordinates were measured with the positioning guides and with no positioning guide (control group). The ΔL*, Δa*, Δb*, ΔE*ab, and ΔE00 were calculated between the control group and the different groups. The CIEL*a*b* color coordinates were analyzed by one-way ANOVA followed by the post-hoc Tukey test (α=0.05). Color differences were interpreted using the 50:50% perceptibility and acceptability visual thresholds. Positioning guides with different colors presented significant differences for all surfaces and color coordinates. ΔE*ab, and ΔE00 mean values for all surfaces and positioning guide colors exceeded the acceptability visual thresholds, except for the bovine tooth surface measured with the green positioning guide. The shade measurement was affected by the color of the positioning guides regardless of the surface that was evaluated.

Can discolored dental composites be bleached in depth?

Previous in vitro studies determined the whitening effects of bleaching products on stained resin composite surfaces. This in vitro study aimed to verify the effectiveness of a whitening system on composite resin previously subjected to pigmentation, specifically examining the depth of whitening effectiveness within the material structure. A commercially available nano-filled composite resin was used. Specimens were stained using a coffee-based solution and a 10% carbamide peroxide-based gel was employed as the whitening agent. The pigment's penetration and the effect of the bleaching gel were evaluated by measuring color (CieLab values) from the outer edge to the inner part of the specimens. Color measurements were taken at 14 points, starting from 0.1 mm from the external perimeter up to 3.0 mm. Analysis of variance tests showed a statistically significant difference between the Control Group (CG), Pigmentation Group, and Whitening Group. The whitening agent was effective up to 1.5 mm in depth, with Whiteness index (W) values not statistically different from those of CG up to 0.5 mm in depth. Whitening agents on nano-filled resin composite previously pigmented appear effective in restoring the W to values similar to the original, particularly in the superficial layers of the sample.

Effect of composite resin containing antibacterial filler on sugar-induced pH drop caused by whole saliva bacteria

Secondary caries around restorations is a major problem and can be attributed to bacteria invading microgaps formed at the tooth-restoration interface. An antibacterial composite resin containing quaternary ammonium silica (QASi) filler has been reported to inhibit enamel demineralization in situ. However, whether the prevention of enamel demineralization by QASi-containing composite resin is because of the reduced metabolic activity of acid-producing saliva bacteria is unclear. The purpose of this study was to compare the effects of QASi-containing composite resin and 2 other restorative materials on the viability of salivary bacteria and sugar-induced acid production. Whole saliva from each of the 30 study participants, 14 at high risk and 16 at low risk for caries, was brought into contact with quadruplicate specimens of 3 restorative materials, Infinix Flowable Composite, an anti-bacterial composite resin containing 1.5% QASi filler (Nobio), Filtek Supreme Flowable Restorative (3M), a conventional flowable composite resin, and dental amalgam (Silmet). Bacterial growth and sugar-induced acid production on each restorative material were measured every 20 minutes for 18 hours. Caries risk groups were compared using the t test and repeated measures analysis of variance (α=.05). When significant, Bonferroni multiple comparisons were used. On average, the saliva with the QASi-containing composite resin specimens maintained a near-neutral pH, not dropping below pH 6.0. The saliva associated with both conventional restorative materials exhibited a pH drop below 5.5 (P<.001), the critical threshold for tooth demineralization according to the Stephan curve. Virtually no growth was measured on the surface of the antibacterial composite resin, whereas bacteria grew on the conventional composite resin and dental amalgam (P<.001). No differences were observed between participants at high and low risk of caries. Unlike amalgam and conventional composite resin, the QASi-containing composite resin showed a near-complete shutdown of the metabolic activity of salivary bacteria upon contact and virtually no bacterial viability. This suggests that the prevention of tooth demineralization by QASi-containing restoratives is associated with a significant reduction in bacterial metabolic activity.

Repair bond strength of bulk-fill composites: influence of different primers and direction of debonding stress

Background The purpose of this in vitro study was to evaluate the effect of different adhesion primers on the repair bond strength of bulk-fill resin composite and short-term hydrolytic stability of the repair interface before and after accelerated aging. In addition, direction of debonding stress was examined. Materials and methods Bulk-fill substrates were aged in water for 14 days at 37 °C. Smooth resin composite surfaces were prepared for the substrates with a superfine grinding paper (FEPA #500, #1200, #2000). Test specimens were produced by attaching bulk-fill composite to the substrate surfaces, using three different primer/bonding systems. Specimens were aged 24 h at 37 °C in water, or thermal cycled (5–55 °C/5,000 cycles). Subsequently, shear bond strength and micro-tensile bond strength were evaluated. In total there were 60 specimens for the shear bond strength and 60 specimens for the micro-tensile bond strength measurements (30 stored in water 24 h, 30 thermal cycled, n = 10 in each primer/bonding mode). Results The mean shear bond strength was 9.1–13.1 MPa after 24 h water storage and 6.9–10.7 MPa after thermal cycling. The mean micro-tensile bond strength was 28.7–45.8 MPa after 24 h water storage and 22.7–37.9 MPa after thermal cycling. Conclusion The Ceramic primer (silane containing) seems to perform better than the three-step etch and rinse adhesive or the Composite primer. Shear-type stress had an adverse effect on the repair bond strength of bulk-fill resin composites.

A Remineralizing and Antibacterial Coating for Arresting Caries.

Dental caries is a dynamic disease induced by the unbalance between demineralization of dental hard tissues caused by biofilm and remineralization of them; however, although various effective remineralization methods have been well documented, it is a challenge to reestablish the balance by enhancing remineralization alone while ignoring the antibacterial therapy. Therefore, the integration of remineralizing and antibacterial technologies offers a promising strategy to halt natural caries progression in clinical practice. Here, the conception of interrupting dental caries (IDC) was proposed based on the development of dual-functional coating with remineralizing and antibacterial properties. In this study, bovine serum albumin (BSA) loaded octenidine (OCT) successfully to form a BSA-OCT composite. Subsequently, through fast amyloid-like aggregation, the phase-transited BSA-OCT (PTB-OCT) coating can be covered on teeth, resin composite, or sealant surfaces in 30 min by a simple smearing process. The PTB-OCT coating showed satisfactory effects in promoting the remineralization of demineralized enamel and dentin in vitro. Moreover, this coating also exerted significant acid-resistance stability and anti-biofilm properties. Equally importantly, this coating exhibited promising abilities in reducing the microleakage between the tooth and resin composite in vitro and preventing primary and secondary caries in vivo. In conclusion, this novel dual-functional PTB-OCT coating could reestablish the balance between demineralization and remineralization in the process of caries, thereby potentially preventing or arresting caries.

The Effect of Bonding Surface Design on Shear Bond Strength of 3D-Printed Orthodontic Attachments.

This study compared the shear bond strength (SBS) of four innovative designs of the bonding surface of 3D-printed orthodontic attachments with conventional mesh design. In this in vitro study, the bonding surface design in different groups was as follows: Group 1, flat surface without any feature as a negative control; Group 2, concentric circles with no cuts; Group 3, concentric circles with 16 radial cuts; Group 4, concentric circles with 32 radial cuts; Group 5, small cones with a flat end and rounded edges; Group 6, mesh-based commercially available metal brackets of the maxillary central incisor (standard edgewise, Dentaurum®) as a positive control (n = 20). In Groups 1-5, attachments were designed with SolidWorks® Software and printed with a 2K DLP-LCD printer with hard tough resin (eSun®). All the samples were bonded to the restorative composite resin (Solafil®) surfaces with orthodontic composite resin (CuRAY-ECLIPSE®). The samples were examined for SBS with a universal testing machine after thermocycling (1,000 cycles of 5‒55°C). Data were analyzed with Shapiro-Wilk, one-way ANOVA, and Bonferroni tests. The statistical significance level was set at 0.05. The mean SBS was significantly different between all the groups (P < 0.001) except for Groups 2 and 5 (P = 1.00) and Groups 2 and 6 (P = 1.00). Group 4 had the highest mean of SBS. The bonding surface design significantly influenced the SBS of orthodontic attachments. The concentric circles with 32 cuts had higher bond strength than other designs and can be suggested as a new bonding surface design for orthodontic attachments.

Mathematical-Physical Description of the Oxygen-Inhibited Layer (OIL) in Nanofilled Dental Polymers

This research evaluates the presence of the oxygen-inhibited layer (OIL) on the top surface of a photopolymerized dental composite resin protected with a glycerin layer. This evaluation was conducted using physical and mathematical methods. Polymerized discs were fabricated to evaluate Vickers microhardness (VHN), and pre-and post-polymerized samples were used for the calculation of C-O/C-H ratios through Fourier Transform Infrared Spectroscopy (FTIR) (n=10), using two types of glycerin, one for medical use (MG) and another for dental use (DG). Surface hardness decreased from MG to DG to CO, and the increase in C-O/C-H ratios decreased in the same order (p&lt;0.05). Samples protected with medical and dental glycerin layers are harder and exhibit lower C-O/C-H bond ratios than the control group.

Evaluation of the Effect of Different Antioxidants on Resin Bond Strength to Enamel after Bleaching: An In Vitro Study.

To compare and evaluate the efficacy of 10% sodium ascorbate (SA) solution, 10% alpha-lipoic acid (ALA) solution, 10% propolis solutions (PLS), and 10% pomegranate peel extract (PPE) solution on the shear bond strength (SBS) between composite resin and bleached enamel after 60 minutes. Ninety extracted teeth were divided into 6 subgroups (n = 15) based on the antioxidant applied: Group I: Bleaching + application of 10% SA solution for 60 minutes. Group II: Bleaching + application of 10% ALA solution for 60 minutes. Group II: Bleaching + application of 10% PLS for 60 minutes. Group IV: Bleaching + application of 10% PPE solution for 60 min. Group V: Positive control (PC) bleaching without antioxidant application. Group VI: Negative control (NC) specimen neither subjected to bleaching nor application of an antioxidant solution. About 35% hydrogen peroxide (HP) was used for bleaching the labial surfaces in the groups considered. Labial surfaces were then bonded with composite using a customized cylindrical mold followed by storage in distilled water for 24 hours and shear bond strength was tested using universal testing machine. The mean shear bond strength values for groups I, II, III, IV, V, and VI are 5.04, 2.29, 5.02, 4.07, 1.42, and 9.08 respectively. The peak shear bond strength value is obtained for the negative control group; whereas the lowest mean SBS value is obtained for the positive control group. All herbal extracts used in the present study have demonstrated a reversal of reduced SBS between resin composite and bleached enamel surface. The reduction in bond strength of adhesive restorations was conventionally overcome by delaying the bonding procedure for a specified period resulting in prolonged treatment duration and multiple appointments. Sodium ascorbate is most commonly used but it is postulated to form a porous scaffold capable of harboring bacteria. Herbal antioxidants are gaining popularity in this regard as they are naturally derived, effective and affordable phytochemicals in addition to being viable alternatives against drug-resistant strains of microorganisms.

Modulation of implants PEEK to composite resin shear bond strength and surface roughness on pre-treatment with contemporary air abrasion techniques vs photodynamic therapy vs conventional diamond grit bur

AimThe chief aim of the study was to determine/equate the surface roughness (SRa) and shear bond strength (BS) of pretreated PEEK discs with contemporary air abrasion techniques, photodynamic (PD) therapy by curcumin photosensitizer (PS) and conventional diamond grit straight fissure bur adhered to the composite resin discs. Material and methodTwo hundred discs of PEEK were prepared of 6 mm × 2 mm × 10 mm dimension. The discs were randomly divided into five groups (n = 40) for treatment, Group I: treatment with deionized distilled water (control group); Group II: PD therapy using curcumin PS; Group III: discs treated and abraded with air-borne particles (ABP) silica (30 μm particle size) modified alumina (Al); Group IV: ABP of alumina (110 μm particle size); and Group V: The PEEK were finished with 600-μm grit size straight diamond cutting bur installed in high speed hand-piece. The surface profilometer was used to evaluate the values of surface roughness (SRa) of pretreated PEEK discs. The discs were luted and bonded to discs of composite resin. The bonded PEEK samples were placed in Universal testing machine to evaluate shear BS. The type of BS failure for PEEK discs pre-treated with five regimes respectively was evaluated under stereo-microscope. The data was statistically analyzed using one-way ANOVA and the comparisons between mean values of shear BS were evaluated by Tukey's test (ρ≤0.05). ResultsThe PEEK samples pre-treated with diamond cutting straight fissure burs displayed statistically significant highest value of SRa values (3.258± 0.785 µm). Similarly, the shear BS was observed to be higher for the PEEK discs pre-treated with straight fissure bur (22.37±0.78 MPa). A comparable difference but not statistically significant difference was observed between PEEK discs pre-treated by curcumin PS and ABP-silica modified alumina (ρ ≥ 0.05). ConclusionPEEK discs pre-treated with diamond grit straight fissure bur displayed highest values of SRa and shear BS. It was trailed by ABP-Al pre-treated discs; whereas the SRa and shear BS values for the discs pre-treated with ABP-silica modified Al and curcumin PS did not show competitive difference.

Study of Streptococcus mutans in Early Biofilms at the Surfaces of Various Dental Composite Resins.

Biofilm deposit on the composite restoration is a common phenomenon and bacterial growth follows the deposition. The study aims to evaluate Streptococcus mutans (S. mutans) early biofilm formation on the surfaces of various dental composite resins by using the real-time quantitative polymerase chain reaction (qPCR) technique. Thirty-two discs, where eight discs were in each group of Filtek Supreme Ultra (FSU; 3M, St. Paul, MN), Clearfil AP-X (APX; Kuraray Noritake Dental Inc., Tokyo, Japan), Beautifil II (BE2; Shofu, Inc., Kyoto, Japan), and Estelite Sigma Quick (ESQ; Tokuyama Dental, Tokyo, Japan), were fabricated and subjected to S. mutans biofilm formation in an oral biofilm reactor for 12 hours. Contact angles (CA) were measured on the freshly fabricated specimen. The attached biofilms underwent fluorescent microscopy (FM). S. mutans from biofilms were analyzed using a qPCR technique. Surface roughness (Sa) measurements were taken before and after biofilm formation. Scanning electron microscopy (SEM), including energy dispersive X-ray spectrometer (EDS) analysis, was also performed for detecting relative elements on biofilms. The study showed that FSUdemonstrated the lowest CA while APXpresented the highest values. FMrevealed that condensed biofilm clusters were most on FSU. The qPCR results indicated the highest S. mutans DNA copies in the biofilm were on FSU while BE2was the lowest (p < 0.05). Sa test signified that APX was significantly the lowest among all materials while FSU was the highest (p < 0.05). SEM displayed areas with apparently glucan-free S. mutans more on BE2 compared to APX and ESQ, while FSU had the least. Small white particles detected predominantly on the biofilms of BE2 appeared to be Si, Al, and F extruded from the resin. Differences in early biofilm formation onto various composite resins are dependent on the differences in materialcompositions and their surface properties. BE2 showed the lowest quantity of biofilm accumulation compared to other resin composites (APX, ESQ, and FSU). This could be attributed to BE2 proprieties as a giomer and fluoride content.

Synthesis of ZnO Nanorod-Decorated Graphene Oxide for Application in Dental Resin Composites

Biofilm formation on resin composite surfaces is associated with the occurrence of secondary caries around restorations. As a promising antibacterial nanomaterial, graphene oxide is effective to suppress the viability of the cariogenic bacteria Streptococcus mutans (S. mutans). However, GO naturally expresses brown, which limits its potential application in dentistry. In this work, ZnO nanorod-decorated graphene oxide (GOn@ZnO) particles were synthesized via a facile hydrothermal method, and their optical property was regulated by changing the amount of seeded GO (n value) in the microemulsion. Among all hybrid particles, GO3@ZnO exhibited a bright gray color and lowest UV absorbance and therefore was selected as an optimal functional filler to produce dental composites with different loadings (0.1, 0.5, 1, and 3 wt %). The effects of GO3@ZnO loading on light transmittance, polymerization conversion, mechanical property, in vitro cell viability, and antibacterial effect of dental composites were systematically explored. The results exhibited that the 0.5 wt % GO3@ZnO-filled composite demonstrated comparable degree of conversion (60 s), higher flexural strength and modulus, and similar cell viability to the control. This composite also effectively inhibited the growth of S. mutans, giving a significantly lower bacterial concentration (3.9 × 107 CFU/mL) than the unfilled resin (8.5 × 107 CFU/mL) and the 0.5 wt % GO-filled composite (6.6 × 107 CFU/mL), respectively. The introduction of GO3@ZnO in dental composites could be a promising strategy to prevent secondary caries and extend service life.