Composite Resin Research Articles

Flexural Strength of Nanohybrid Composite Resin: An in-vitro Study

In the present study, the Flexural strength of nanohybrid composite was compared with conventional microfilled composite resin in vitro. Thirty nanohyrid and 30 conventional microfilled composite resins were subjected to Flexural strength measurement as follows; a teflon mold (4 mm in diameter and 6 mm in depth) was filled with materials, light cured through the glass slides for 40 sec top and bottom surfaces. Then the specimens were taken out from the mold, again light curing for 40 sec, stored in dry condition and placed into a Flexural strength tester and loaded until fracture of the sample. Student t-test was performed to assess the differences between two groups and a value of p >0.05 was considered as statistically significance. The results showed that the means ± SD Flexural strength of nanobybrid and conventional microfilled composite resin were 118.70 ± 3.90 Mpa and 77.43 ± 2.65 Mpa, respectively and the differences were statistically significant. It can be concluded that nanohybrid is superior to conventional microfilled composite resin in respect to Flexural strenth in class II restorations of permanent molar teeth.

Cost-effectiveness of expanding national health insurance coverage for composite resin restorations in cancer patients in South Korea

ObjectivesCancer patients often have compromised oral health, making them vulnerable to severe dental caries and restoration failures. Due to the nature of cervical or anterior caries in cancer patients, the use of adequate restorative materials is important. However, public dental insurance coverage for composite treatments varies among countries and only glass ionomer cements (GICs) are covered in all age groups in South Korea. This study examined the cost-effectiveness of expanding national health insurance coverage to include resin composite (RC) restorations as compared with GIC in cancer patients. MethodsData from cancer patients who received direct restoration using GIC were identified from the National Health Screening Cohort. The relative effect of RC compared to GIC was determined through a meta-analysis, which was then utilized in calculating corresponding transition probabilities within a multi-state model. A Markov-chain Monte Carlo microsimulation was performed to estimate useful life-years and total treatment costs at the tooth level. The incremental cost-effectiveness ratio (ICER) of RC versus GIC was calculated, considering scenarios with and without expanded national health insurance coverage. The robustness of the results was confirmed through various sensitivity analyses. ResultsBetween the two materials, RC resulted in a 0.4-year longer useful life. From a limited societal perspective, it cost $9.6 less with expanded coverage but $24.3 more without expansion, resulting in an ICER of -$25.2 and $63.9 per tooth-year, respectively. From a patient's perspective, the ICER values were -$72.7 versus $138.8 per tooth-year, respectively, translating into $200 more in savings with the expansion. Various sensitivity analyses consistently demonstrated a smaller ICER when insurance coverage was expanded. ConclusionsThe expansion of national health insurance coverage to include RC restorations for cancer patients appears to be clearly cost-effective. This emphasizes the need for further policy considerations to ensure access to dental care for cancer patients. Clinical SignificanceTimely management of dental caries is crucial for cancer patients, as untreated caries can escalate into severe oral conditions, negatively impacting treatment outcomes and increasing care costs. Expanding a national health insurance coverage for cancer patients in the treatment of early dental lesions is necessary to prevent advanced dental diseases.

Novel insights into the correlation composition-structure-property of recyclable carbon fiber reinforced thermosetting resin composites

As widely used lightweight and high-strength materials, the sustainable development of thermosetting composites is hampered by their limited recyclability. Developing simple methods for the efficient and upgraded recycling is desirable but challenging. Herein, carbon fiber reinforced degradable thermosetting resin composites were prepared, and the effects of resin degradation process and its derivatives on the sustainable recycling of carbon fiber were studied. Through the tunable departure and re-adsorption of degradation derivatives in cleaning post-treatment, recycled carbon fibers achieved not only non-destructive recovery but also simultaneously improvements in tensile strength from 3.0 GPa to 3.7 GPa and surface energy from 47.2 mN/m to 66.7 mN/m. The adhered derivatives, rich in -NH- and oxygen-containing groups, exhibited good interactions with the fiber surface and epoxy resin. Benefiting from this, the inter laminar shear strength of recycled carbon fibers reinforced epoxy composite effectively improved 24.3 %. In this work, directly reusing resin degradation products for the recycling of reinforced fibers was proposed and the key role of the composition and distribution of degradation products in recycling properties was revealed. The strategy of integrating characteristics of components to enhance material recyclability is expected to have widespread applicability, promoting the sustainable transition for thermosetting composites.

Comparison of composite resins containing UV light-sensitive chitosan derivatives in stereolithography (SLA)-3D printers.

This study produced composite resins by combining acrylate, chitosan (CH), carboxymethyl chitosan (CMCH), hydroxypropyl chitosan (HPCH), and hydroxyethyl chitosan (HECH) to create materials suitable for use in 3D stereolithography (SLA) printers. Tripropylene glycol diacrylate (TPGDA), urethane acrylate (UA), and photoinitiator (Diphenyl (2, 4, 6-trimethylbenzoyl) phosphine oxide (TPO)) were mixed. CH and its derivatives were added separately to the resin to obtain composite resins. The mechanical test results are clear; the optimum TPGDA: UA ratio was 1:1, the cure time was 60s, and the TPO ratio was 1%. The optimum viscosity of the resin is 340-350cP. Hydrophobic/hydrophilic properties of cured composite resins were examined. The addition of CH and its derivatives to the resin caused a decrease in compressive strength. Adding up to 2.5% CH, CMCH, and HECH to the resin significantly increased the tensile strength of the resin, giving it flexibility. The gel content of cured composite resins was between 97.72% and 96.11%. The cured composite resins demonstrated high chemical and solvent resistance to HCl, NaOH, and HF but exhibited limited resistance to toluene and chloroform. The accelerated UV aging test results show that adding CH derivatives to the resin makes the composite resin more prone to photooxidative aging.

Influence of Polymerization Protocol on Adhesion and Proliferation of Streptococcus mutans on Three Dental Composite Resins.

Background/Objectives: The aim of this in vitro study was to analyze and compare the Streptococcus mutans ability to adhere and form biofilm on the surface of light-cured VS heat-cured dental composite resins; Methods: Three composite resins with different chemical formulations were selected: GrandioSO (GR), Venus Diamond (VD) and Enamel Plus Hri Biofunction (BF). Disk-shaped specimens were manufactured by light-curing the composite resins (light-cured subgroups) and subjecting them to a further heat-curing cycle at 80° for 10 min (heat-cured subgroups). Specimens were analyzed for planktonic CFU count (CFU/mL), sessile CFU count (CFU/mL) and for biomass quantification (OD570nm); Results: The planktonic CFU count was higher in all the light-cured subgroups than in the heat-cured subgroups (light-cured: GR = 7.23 × 106, VD = 2.14 × 107, BF = 4.40 × 107; heat-cured: GR = 4.89 × 106, VD = 4.95 × 106, BF = 2.80 × 107), with a statistically significant increase for BF and VD. Focusing on the sessile CFUs, both GR (light-cured = 7.49 × 106; heat-cured = 3.97 × 106) and VD (light-cured = 2.93 × 107; heat-cured = 6.07 × 106) showed a significantly increased number of colonies in the light-cured subgroups. The OD570nm values recorded for the light-cured BF subgroup (0.4280) were significantly increased compared to the heat-cured BF subgroup (0.1931); Conclusions: A more complete polymerization protocol seems to lead to a potential reduction in the risk of secondary caries.

Effect of Prolonged Curing on Resin Composites' Polymerization Properties

Effect of Prolonged Curing on Resin Composites' Polymerization Properties

Effect of lateral extent of pulp tissue removal on the outcome of partial pulpotomy for managing cariously exposed mature permanent molars with symptomatic irreversible pulpitis: A randomized clinical trial.

The aim of this study is to compare the outcomes of restricted partial pulpotomy (R-PP) versus extended partial pulpotomy (E-PP) for managing cariously exposed mature permanent molars with symptomatic irreversible pulpitis (SIP). This double-arm, parallel designed randomized clinical trial was registered at clinicaltrials.gov (registration number: NCT05406557). Following random allocation, 43 participants of each group received the designated intervention. In the R-PP group, 2-3 mm of superficial pulp tissue was removed only from the exposure site, while chamber was completely de-roofed and 2-3 mm of superficial pulp tissue from entire chamber was removed in the E-PP group. Haemostasis was achieved using 3% sodium hypochlorite-soaked cotton pellets. Upon haemostasis, ProRoot mineral trioxide aggregate (ProRoot MTA) was placed over the pulpal wound, overlaid with a resin-modified glass ionomer liner, and restored with composite resin in the same visit. Outcome measures included clinical and radiographic success evaluation at 6 and 12 months, and pain assessment using the visual analogue scale pre-operatively and daily for 7 post-operative days. Nonparametric tests were used for variables including patient's age, pain intensities, mean analgesic consumption, and haemostasis time. Categorical variables including gender, caries type, analgesic intake, hard tissue barrier formation, clinical and radiographic success, and pulp sensibility responses were assessed using Chi-square or Fisher's exact test. Tooth survival was analysed using Kaplan-Meier analysis. A total of 81 cases were analysed at 12 months follow-up. Comparable success was observed in both groups (97.6% in E-PP & 97.5% in R-PP; p > .05). The R-PP group reported significantly lower pain scores on the 1st and 2nd post-operative days than E-PP (p < .05) and required significantly less analgesic intake (p < .05). Hard tissue barrier formation was significantly lower in the R-PP group (p < .05). No significant differences were observed between groups regarding haemostasis time, pulp sensibility responses, and tooth survival (p > .05). Both the PP approaches exhibited comparable success for managing cariously exposed mature permanent molars with SIP. Given the conservative nature of R-PP, it may be used as preferred PP approach for managing such cases. Being the first study of this kind, further work is necessary to draw definitive conclusions.

Ablation resistance and high-temperature insulation capacity of TiB2-B4C modified Al-coated carbon fibre/boron phenolic resin ceramizable composites

The inherent susceptibility to oxidation limits the application of carbon fibre/phenolic resin composites (CF/Ph) in the thermal protection of hypersonic vehicle engines. Herein, TiB2-B4C modified Al-coated carbon fibre/boron phenolic resin ceramizable composites were fabricated. The optimal ceramizable composite (T30C10) exhibited excellent ablation resistance and high-temperature insulation capacity at a linear ablation rate and bottom-surface temperature of -0.00768 mm/s and 129.8 °C, respectively. Oxygen consumption and inhibition, carbon fixation, and self-healing effects contributed to the excellent ablation resistance, and the effects of the Al coatings and carbothermal reduction reactions led to excellent high-temperature insulation capacities.

Riboflavin-ultraviolet-A collagen crosslinking treatments in improving dentin bonding and resistance to enzymatic digestion

Background/purposeThe efficacy of riboflavin-ultraviolet-A (RF-UVA) treatment in crosslinking collagen and improving dentin bonding has been proven. However, biodegradation of the hybrid layer may compromise the bonding. The purpose of this study was to evaluate different RF-UVA treatments regarding their ability to preserve dentin bonding from enzymatic digestion. Materials and methodsCollagen subjected to different RF (0.1 %, 1 %)-UVA (1, 2, 5 min) treatments and 5 % glutaraldehyde (GA), without or with enzymatic digestion, were examined by gel electrophoresis (SDS-PAGE). Twenty-five teeth with exposed dentin were primed with one of three RF-UVA treatments (0.1 %RF/1-minUVA, 0.1 %RF/2-minUVA, and 1 %RF/1-minUVA), GA, or distilled water after acid-etching, then restored with an adhesive and a resin composite. After 24-h storage, these teeth were sectioned into microbeams. Half of them received an early microtensile bond strength (μTBS) test, while the other half was stored in enzyme solution for 7 days before testing. Nanoleakage and hybrid layer degradation were examined by TEM. ResultsAccording to SDS-PAGE results, all groups showed the dissipation of intense γ bands of collagen after digestion. For the early bonded specimens and after enzymatic digestions, 0.1 %RF/2-minUVA treated group presented the highest μTBS and none of premature failure. Its TEM images showed less nanoleakage after digestion, which is contributed to the well suspended collagen fibrils and resin infiltration in the hybrid layer. ConclusionRF-UVA treatment attained collagen crosslinking effects to improve resin-dentin bonding. 0.1 %RF/2-minUVA effectively enhanced dentin bond strength and resistance to enzymatic digestion by optimally expanding dentinal collagen matrix to facilitate hybrid layer formation.

Multistage rigid and flexible structure-decorated basalt fibers for epoxy resin composites with synergistically enhanced strength and toughness

In this study, we report the construction of a multistage rigid and flexible structure using boron nitride (BN) and MXene (MX, Ti3C2Tx) nanosheets through the conjugation with (3-aminopropyl) triethoxysilane (APTES). The created structure is further utilized to modify basalt fibers (BFs) to obtain BF/epoxy resin (BF/EP) composites via a simple coating process. The rigid two-dimensional materials (2DMs), BN and MX, significantly enhance the roughness of the BF surface, while the silane (APTES) acts as a flexible bridge for linking BFs, BN, and MX. Consequently, the constructed multistage rigid and flexible structure synergistically enhances the strength and toughness of the composite through effective mechanical interlocking, chemical bonding, and multistage energy dissipation. Meanwhile, this complex structure prevents the stress concentration and promotes uniform stress transfer between BFs and EP. This study provides a promising strategy to construct an effective interface layer and achieve high-performance BF/EP composites by introducing 2DMs and a silane linker.

Marginal Adaptation of Self Adhesive Bulk-fill Resin Composite vs Conventional Resin Composite and Resin Modified Glass- ionomer: A Comparative Study.

Marginal Adaptation of Self Adhesive Bulk-fill Resin Composite vs Conventional Resin Composite and Resin Modified Glass- ionomer: A Comparative Study.

Dielectric properties and temperature dependence of holey graphene/resin composites

In order to enhance the survivability of fighter aircraft, it is crucial to develop microwave absorbing (MA) materials with a low dielectric-temperature dependence. Reduced graphene oxide (RGO) has potential for military stealth applications, but its wave absorbing properties are highly sensitive to temperature fluctuations due to significant conductivity loss. In this work, conductivity and polarization loss are balanced through microstructural design to disrupt the conductive pathways by creating holes on the graphene surface. The holey RGO aerogel/phenolic resin (HRGA/PF) composites with a hierarchical pore structure were synthesized through combining freeze-drying and PF infiltration. The results show that the HRGA/PF composites possess excellent X-band full frequency absorption performance in the temperature range of 25 °C–250 °C, and the reflection loss (RL) is optimized to −62.78 dB. This work expands feasible thoughts for the design of stable MA materials with wide temperature range.

Immediate and Delayed Repair Of Bulk-Fill Composite Resin

Immediate and Delayed Repair Of Bulk-Fill Composite Resin

Effect of Inter-Implant Distance on Fracture Resistance of Implant-Supported Provisional Fixed Dental Prosthesis.

This study aimed to identify the ideal interimplant distance for optimum outcome on immediately loaded implant supported prosthesis. Hence this study was taken up to analyze the effect of varying interimplant distance on fracture resistance of implant supported provisional fixed dental prosthesis (FDP). A total of 24 bis-acrylate composite resin samples were prepared. Interimplant distance was present in the metal die for placement of dummy implants at distances of 14 mm, 21 mm, and 30 mm respectively. Wax-up for 3-unit, 4-unit, and 5-unit implant-supported provisional restoration was made. Silicone molds were used for making multiple interim prostheses using bis-acrylate composite material. All samples were subjected to fracture test in the universal testing machine with a crosshead speed of 1 mm/min. All samples were loaded with gradual force starting from 100 N until it fractured. The load was applied at the center of prosthesis. Data was analyzed by one-way analysis of variance and Bonferroni post hoc test. Mean fracture resistance of 3-unit provisional FDP at 14 mm of interimplant distance showed 1342.61 ± 179.15 N. Mean fracture resistance of 4-unit provisional FDP at 21 mm of interimplant distance showed 1420.44 ± 170.37 N. Mean fracture resistance of 5-unit provisional FDP at 30 mm of interimplant distance showed 791.61 ± 203.59 N. Both 14 mm and 21 mm of interimplant distance are suitable span lengths to be considered for the optimum outcome during immediately loading with implant-supported provisional restorations. Limitations of the study were that force application was static in nature and not dynamic and the arch form was not "U" shaped but longitudinal using Bis-Acryl material only with no cantilever. Future studies can be done to evaluate the fracture resistance of bis-acrylate material considering biomechanics and arch form of natural dentition. Distal cantilever should be considered along with different material for fabricating provisional restoration.

Aesthetic rehabilitation of enamel hypoplasia with direct composite resin

Aesthetic rehabilitation of enamel hypoplasia with direct composite resin

Evaluation of Preheating Methods for Bulk-Fill Thermoviscous Composite in Non-Carious Cervical Lesions: A 24-month Randomized Controlled Trial

This 24-month, double-blind, split-mouth randomized equivalence clinical trial compared the retention rates of a bulk-fill thermoviscous composite resin using two different preheating methods for the restoration of non-carious cervical lesions (NCCLs). A total of 120 NCCLs were randomized into two groups (n = 60 each). In one group, a bulk-fill thermoviscous composite resin (VisCalor bulk, Voco GmbH) was preheated using a dispenser heater (DH, VisCalor Caps dispenser/warmer), while in the other group, the same resin was preheated with a bench heater (BH, Caps Warmer). In the BH group, the composite underwent preheating at 68°C using a heating bench for 3 min while in the DH group, the composite was preheated at the same temperature for 30 s using a dispenser heater. Subsequently, the preheated bulk-fill thermoviscous composite resin was directly applied to the NCCLs. The restorations were evaluated at baseline, and after 6, 12, 18, and 24 months of clinical service using the FDI criteria. The total working time was recorded. The study used TOST-P to assess groups equivalence, Kaplan-Meier analysis for retention/fracture rate, log-rank test for secondary outcomes' survival distributions, and paired t-tests for comparing time per clinical step between groups (α = 0.05). After 24 months, 106 restorations were evaluated. Four restorations were lost-two from the DH group and two from the BH group-resulting in similar retention rates for both groups (96.1%, 95% CI 86.8 - 98.9, p > 0.05). The hazard ratio was 0.83 (95% CI 0.26 to 2.72), indicating no significant difference between the groups (p > 0.05). All other FDI parameters were deemed clinically acceptable. However, the total working time for the BH group was significantly longer than that for the DH group (p < 0.001). Both preheating protocols employed for the bulk-fill thermoviscous composite resin demonstrated high and equivalent retention rates after 24 months, the other FDI parameters were deemed clinically acceptable over the same period. Clinicians can choose either method for heating the thermoviscous composite resin for restoration of non-carious cervical lesions, as they do not impact important clinical outcomes after 24 months. The total working time for the bench heater is higher than that for the dispenser heater due to the need for preheating of the bench heater.

Aeshetic restoration of peg laterals with direct composite resin

Aeshetic restoration of peg laterals with direct composite resin

Shear Bond Strength of Five Different Repair Systems to Three Different Ceramic Materials.

The purpose of the current study was to investigate the shear bond strength of composite resin in five different ceramic repair systems for three different ceramic materials. 225 monolithic zirconia (Zr) and lithium disilicate (LDS) and cobalt chromium (CoCr) specimens with feldspathic porcelain (FP) veneer were fabricated (N=75 per material). The specimens underwent thermo-cycling and were randomly divided into five groups for the following intra-oral repair systems (n=15): 1) Clearfil Ceramic Primer Plus, Kuraray Noritake, Japan; 2) Ibond Intraoral Repair Kit, Kulzer, Germany; 3) VOCO Cimara, VOCO GmbH Germany; 4) Ivoclar Vivadent, Ceramic Repair System Kit, IvoclarVivadent, Liechtenstein; 5) Ultradent Porcelain Repair Kit, Ultradent Products Inc, USA. After surface conditioning, composite was applied using a cylindrical mold and a second round of thermocycling was performed. Each specimen was then subjected to shear load until failure. Microshear bond strength was compared using analysis of variance (one-way ANOVA, Tukey's test, a <0.05). Type of porcelain repair kit significantly affected the shear bond strength. For Zr, the repair systems from Kulzer and VOCO had significantly higher shear bond strength than the other systems (p<0.001) without significant difference between Kulzer and VOCO. For the LDS and CoCr with FP, hydrofluoric acid had the highest shear bond strength (p<0.001). For zirconia, a 10-Methacryloyloxydecyl dihydrogen phosphate (10-MDP) system should be used. The results also suggest that a cleaning bur may be beneficial. For glass-based ceramics and feldspathic porcelain, etching with hydrofluoric acid remains the product of choice.

Shear-Bond Strength of Composite Resins Repaired with Injectable Composite

Shear-Bond Strength of Composite Resins Repaired with Injectable Composite

Effect of Polishing Systems on Composite Resin Colour Stability

Effect of Polishing Systems on Composite Resin Colour Stability