Supreme XT Research Articles

A Finite Element Method Study on a Simulation of the Thermal Behaviour of Four Methods for the Restoration of Class II Cavities.

The possibility of dental pulp damage during dental procedures is well known. According to studies, during finishing and polishing without cooling, temperatures of up to 140 °C or more can be generated. There are many studies that have analysed the influence of the finishing and polishing of fillings on the mechanical parameters, but the analysis of thermal parameters has led to uncertain results due to the difficulty of performing this in vivo. Background: We set out to conduct a study, using the finite element method, to determine the extent to which the type of class II cavity and the volume of the composite filling influence the duration of heat transfer to the pulp during finishing and polishing without cooling. Materials and Methods: A virtual model of an upper primary molar was used, with a caries process located on the distal aspect, in which four types of cavities were digitally prepared: direct access, horizontal slot, vertical slot and occlusal-proximal. All four cavity types were filled using a Filtek Supreme XT nanocomposite. Results: The study showed that the filling volume almost inversely proportionally influences the time at which the dental pulp reaches the critical temperature of irreversible damage. The lowest duration occurred in occlusal-distal restorations and the highest in direct access restorations. Conclusions: based on the results of the study, a working protocol can be issued so that finishing and polishing restorations without cooling are safe for pulpal health.

Microleakage Evaluation of a Silorane-Based and Methacrylate-Based Packable and Nanofill Posterior Composites (in vitro comparative study)

This study compared in vitro the microleakage of a new low shrink silorane-based posterior composite (Filtek™ P90) and two methacrylate-based composites: a packable posterior composite (Filtek™ P60) and a nanofill composite (Filtek™ Supreme XT) through dye penetration test. Thirty sound human upper premolars were used in this study. Standardized class V cavities were prepared at the buccal surface of each tooth. The teeth were then divided into three groups of ten teeth each: (Group 1: restored with Filtek™ P90, Group 2: restored with Filtek™ P60, and Group 3: restored with Filtek™ Supreme XT). Each composite system was used according to the manufacturer's instructions with their corresponding adhesive systems. The teeth were then thermocycled, immersed in 1% methylene blue dye for 24 hours at room temperature, embedded in auto-polymerizing acrylic resin and sectioned longitudinally bucco-lingually. Microleakage was evaluated by assessing the linear dye penetration at the tooth/restoration interface occlusally and gingivally. The highest microleakage score occlusally or gingivally was recorded and the results were analyzed statistically using SPSS version 13. The results of this study showed that the silorane-based posterior composite Filtek™ P90 showed significantly less microleakage than the methacrylate-based packable composite (Filtek™ P60) and the nano-filled composite (Filtek™ Supreme XT) when the tooth-restoration interface is located in enamel.

Flexural Strength of Conventional or Bulk-fill Resin Composite Repaired with High- or Low-viscosity Restorative Materials.

To evaluate the flexural strength of two types of high-viscosity resin composites (conventional or bulk-fill) that were repaired with either high-viscosity composites (conventional or bulk-fill) or low-viscosity composites (conventional or bulk-fill) of the same manufacturer (3M Oral Care, St Paul, MN, USA). Specimens (25 mm × 2 mm × 2 mm) of both conventional nanofilled resin (Filtek Z350XT), and bulk-fill nanofilled resin (Filtek One Bulk Fill) were prepared. After fracture of the specimens in the 3-point bending test (initial), half of the specimens were repaired immediately afterwards (24 hours), and the other half were repaired after 6 months of storage in distilled water. Repairs were performed with (n=15) high-viscosity resin composites (Filtek Z350XT, Filtek One Bulk Fill), or their low-viscosity versions (Filtek Supreme XT Flow, Filtek Bulk Fill Flowable Restorative). The repair was performed by roughening the surface and applying phosphoric acid, silane, and adhesive. The bending test (results reported in MPa) was performed in a universal testing machine, and the fracture pattern was determined. Data were evaluated by generalized linear models, chi-square test and the Fisher exact test (α=0.05). There was no significant difference between the former pair of high-viscosity resins in terms of initial flexural strength (p=0.42). The repairs performed with low-viscosity resin composites after 24 hours or 6 months obtained higher MPa values compared with those using high-viscosity composites (p=0.0006). There was a significant decrease in MPa values when the repair was performed after 24 hours and an increase after 6 months, regardless of the material (p<0.0001). After 6 months, fractures involving the old (conventional) resin were more frequent in the repair performed with bulk-fill resin composites compared with the conventional composites (p=0.02). Considering the tested products, the material to be repaired did not influence the flexural strength of the repair composite; however, the use of the low-viscosity resin composites resulted in greater flexural strength of the repaired material. The repair of the aged composite resulted in an increase in its flexural strength, regardless of the material repaired or used to perform the repair.

Study on the Restoration of Class II Carious Cavities by Virtual Methods: Simulation of Mechanical Behavior.

The restoration of class II cavities is predominantly carried out with composite materials. Due to the high failure rate in restoring this type of cavity, composite materials with much-improved properties and new application techniques have been promoted. The study aimed to analyze the mechanical behavior of several topical composite materials (nanocomposites, nanohybrids and ormocer) using different application techniques. In a lower second molar, a class II occlusal cavity was prepared. As filling materials, we used the following combinations: Admira Fusion and Admira Fusion Flow, Grandio and Grandio Flow, Filtek Supreme XT and Filtek Supreme Flow. These were applied using a snow plow, injection molded and Bichacho techniques. Three-dimensional scanning of the molar with the prepared cavity was performed, and then scanning of each layer of added composite material was performed, obtaining three-dimensional models. The virtual molar models were analyzed with software specific to the finite element analysis method, where their physical-mechanical properties were entered and assigned to the components of the virtual molar. Simulations at high forces specific to bruxism were then carried out and analyzed, and compared. The values of displacements and strain, for all six analyzed situations, are relatively small (range from 5.25 × 10-6-3.21 × 10-5 for displacement, 6.22 × 10-3-4.34 × 10-3 for strain), which validates all three methods and the materials used. As far as the stress values are concerned, they are similar for all methods (250-300 MPa), except for the snow plow and injection-molded techniques using Grandio and Grandio Flow composites, where the maximum von Mises stress value was more than double (approximately 700 MPa). When using the combination of Grandio and Grandio Flow materials, the 1 mm thickness of the fluid composite layer was found to have a major influence on occlusal forces damping as opposed to 0.5 mm. Therefore, the Bichacho technique is indicated at the expense of the snow plow and injection-molded techniques. The composite materials used by us in this study are state-of-the-art, with clear indications for restoring cavities resulting from the treatment of carious lesions. However, their association and application technique in the case of Class II cavities is of clinical importance for resistance to masticatory forces.

The Cracking Behavior of Two Dental Composite Materials Validated through Multifractal Analyzes.

The aim of this in vitro study was to analyze, both experimentally and theoretically, the mechanical behavior of two types of composite materials used in restoring dental integrity. The samples of each composite resin, namely Filtek Supreme XT (3M ESPE, St. Paul, MN, USA) and Filtek Z250 (3M ESPE, St. Paul, MN, USA), were experimentally analyzed by determining their compressive strength and fracture behavior. The fractured fragments of the samples were subjected to surface evaluation by scanning electron microscopy. The compressive stress-compressive strain dependencies revealed stronger cracking of the Filtek Supreme XT composite than Filtek Z250 prior to fracture. Theoretically, the evaluation was made by means of holographic implementations of such types of composite materials. A Hooke-type equation in a differential form is presented, which links the proposed theoretical model with the experimentally obtained data.

Influence of polishing systems on surface roughness of four resin composites subjected to thermocycling aging

Background: Surface smoothness considered to be a significant part of the appearance and success of the restorative materials. The aim of this study was to assess the influence of four different polishing systems on surface roughness of four resin composite materials when subjected to thermocycling.Materials and Methods: This research was designed as a comparative study. Four resin composites were used which are: Nanofill composite (Filtek Supreme XT), nanohybrid composite (Tetric EvoCeram), microfill composite (Renamel Microfill), and microhybrid composite (Filtek Z250). Sixty disk-shaped specimens of each resin composite were prepared then divided into four groups according to the polishing system (n = 15); which were Sof-Lex Spiral, Diatech Shapeguard, Venus Supra, and Astropol. The specimens of each group were polished following the manufactures' instructions, then surface roughness, Ra values in μm were measured initially and after the specimens subjected to thermal cycling. The influence of resin composites, polishing systems, thermocycling, and their interaction effects on surface roughness (Ra mean values) was statistically analyzed mainly by using the repeated measures two-way analysis of variance test, whereas the Bonferroni''s post hoc test was applied for pair-wise comparisons. P ≤ 0.05 was used as the significant level.Results: The results of this study revealed that Filtek Supreme XT recorded significantly the lowest mean surface roughness (Ra) of 0.2533 ± 0.073 μm (P < 0.001). The Sof-Lex Spiral polishing system revealed significantly the lowest mean surface roughness (Ra) of 0.2734 ± 0.0903 μm (P = 0.004). Regardless of composite type and polishing system, there was a statistically significant increase in mean surface roughness values (Ra) in μm after thermocycling (0.2251 ± 0.0496 μm and 0.3506 ± 0.0868 μm, respectively) (P < 0.001).Conclusion: Resin composite type, polishing method, and thermocycling aging significantly affected the surface roughness of composites; Nanofill composite and Sof-Lex Spiral polishing system provided the lowest values of surface roughness which increased after thermocycling.

Determination of Water Content in Direct Resin Composites Using Coulometric Karl Fischer Titration

This study evaluated the water content and sorption of direct composites over 60 days using coulometric Karl Fischer titration (KFT). Plate-shaped specimens (10 × 10 × 1 mm3 of thickness) were built up using the composites Clearfil Majesty Posterior (CM), Grandio SO (GS), and Filtek Supreme XT (FS). Water contents were determined in non-stored specimens (control) or after storage in distilled water for up to 60 days (n = 5). The amount of water transferred from the specimens heated at 200 °C (isothermal mode) was measured in the Coulometer. The water content of non-stored specimens ranged from 0.28 to 1.69 wt% (5.6 to 31.2 μg/mm3) for GS and FS, respectively. The highest values of water sorption were observed for FS (25.3 μg/mm3 after 60 days). GS and CM showed similar water sorption after 60 days (≈9 μg/mm3), but an ultimate higher water content was observed for CM (0.9 wt%; 22.0 μg/mm3) than GS (0.7 wt%; 14.8 μg/mm3). Except for CM, no significant water sorption was observed between 21 and 60 days of storage. Since all composites presented some base water content, water sorption data alone do not account for the ultimate water content in direct resin-based composites.

Internal Adaptation of Cusp-weakened Class I Preparations Restored with Bulk-fill, Bi-layered, and Incremental Restorative Techniques: A Micro-CT Analysis

The aim was to evaluate the internal adaptation of composite restorations in cusp-weakened Class I preparations restored by incremental, bi-layered, and bulk-fill techniques using a microcomputed tomography analysis (micro-CT). Sixty sound extracted human third molars were prepared with standardized cusp-weakened Class I cavity preparations and divided into six groups (n=10). Two groups were restored using an incremental oblique technique with a nanofilled (Filtek Supreme XT, 3M Oral Care, St Paul, MN, USA) and a nanohybrid composite (GrandioSO, VOCO, Cuxhaven, Germany). The other two groups were restored using a bi-layered technique with a bulk-fill flowable composite base (Filtek Bulk Fill Flowable, 3M Oral Care; X-tra Base bulk-fill flowable, VOCO) covered with the conventional composite of the same type. In the remaining groups, teeth were restored with a single-increment technique using bulk-fill full-body composites (Filtek Bulk Fill Posterior, 3M Oral Care; Admira Fusion, VOCO). All teeth were subjected to thermocycling (20,000 cycles, 5°C and 55°C) and mechanical loading (250,000 cycles, 2.5 Hz, 50 N) before analysis of internal adaptation by micro-CT. One-way analysis of variance (ANOVA) and the Games-Howell test were used to analyze the percentage and volume of internal gaps (p<0.05). There was found to be significantly higher internal adaptation for the nanofilled composite used incrementally or associated with a flowable base compared with the nanohybrid composite used incrementally (p=0.002). Bulk-fill and bi-layered techniques performed similarly in terms of internal adaptation for both types of composites. The incremental technique with the nanofilled composite demonstrated a higher internal adaptation than with the nanohybrid composite.

Degradation of Dental Methacrylate-Based Composites in Simulated Clinical Immersion Media.

The selection of restorative materials with regard to the longevity and durability of a restoration is of crucial importance for daily dental practice and requires that the degradation of the material in the oral environment can be assessed. The aim of this study was to investigate the extent to which the mechanical properties of four (Esthet X, Ceram X, Filtek Supreme XT, and Filtek Supreme XT flow) resin-based composites (RBCs) alter during storage in saliva substitutes (artificial saliva) for 24 h and 28 days and in the context of simulated, more aggressive clinical conditions, including cycles exposure to de- and remineralization, alcohol, or salivary enzymes. For this purpose, flexural strength and modulus were determined in a three-point bending test (n = 20) followed by Weibull analysis, while quasi-static behavior was evaluated by instrumented indentation techniques. Degradation occurred in all RBCs and all aging protocols and was quantifiable at both macroscopic and microscopic levels. The postulated stabilizing effect on degradation through the incorporation of urethane-based co-monomers into the organic matrix or a higher filler loading is refuted. Even though modern RBCs show high clinical survival rates, biodegradation remains an issue that needs to be addressed.

Clinical Evaluation of Flowable Composite Materials in Permanent Molars Small Class I Restorations: 3-Year Double Blind Clinical Study.

This study evaluated the 3-year clinical performance of four different flowable composite materials used in Small Class I restorations in permanent molars. This double-blinded, clinical study analyzed 229 Small Class I restorations/103 children at baseline, 12, 24, and 36 months with modified United States Public Health Services (USPHS) criteria. The tested flowable materials were Voco Grandio Flow + Voco Solobond M, Vivadent Tetric EvoFlow + Vivadent Excite, Dentsply X-Flow + Dentsply Prime&Bond NT, and 3M ESPE Filtek Supreme XT Flow + 3M ESPE Scotchbond Universal. The retention and marginal adaptation rates were highest for Grandio Flow and X Flow materials after 36 months, resulting in the highest score of clinical acceptability at 95.3% and 97.6%, respectively. The Tetric EvoFlow and Filtek Supreme XT Flow had the same retention rate after 36 months at 88.1%. Statistical significance was found in Grandio flow material in postoperative sensitivity criteria (p = 0.021). Tetric EvoFlow showed statistical differences in retention (p = 0.01), color match (p = 0.004), and marginal adaptation (p = 0.042). Filtek Supreme showed statistical differences in retention (p = 0.01) and marginal adaptation (p < 0.001). The flowable composite materials showed excellent clinical efficacy after 36 months of their clinical usage. There was no difference among the tested flowable composite materials quality in Small Class I restorations over time.

Effects of toothbrushing on surface characteristics of microhybrid and nanofilled resin composites following different finishing and polishing procedures

ObjectivesTo evaluate the effects of simulated tooth brushing (STB) on the surface roughness of microhybrid and nanofilled resin composites following different finishing and polishing procedures. Materials and methodsNinety cylindrical-shaped specimens of Filtek Supreme XT (a universal nano resin composite) and Filtek Z250 (a universal microhybrid resin composite) were prepared. The specimens were allocated at random into 9 paired groups each of 10 specimens. The finishing and polishing systems included were Tungsten Carbide bur (TC); Diamond bur (Db); Sof-Lex discs (S); PoGo discs (PG); TC + S; Db + S; TC + PG; Db + PG. Polymerisation against a Mylar strip without finishing and polishing acted as the control. Surface roughness was measured using a 3D non-contact optical profilometer and surface morphology was examined by scanning electron microscopy. Specimens were subjected to the equivalent of four years STB and surface roughness was measured again. ResultsMylar formed surfaces were the smoothest for both composites before and after STB. Finishing with the diamond finishing bur caused significantly greater surface irregularity (p < 0.0001) before and after STB compared to the tungsten carbide bur. The surface treatment with Db + PG resulted in significantly greater surface roughness following STB than all other regimes of finishing and polishing (p < 0.01). ConclusionWhere indicated clinically, finishing is better conducted using a tungsten carbide bur rather than a diamond finishing bur. The combination of tungsten carbide bur/Enhance PoGo and tungsten carbide bur/Sof-Lex surface protocols produced a similarly smooth finish for both composites. The composite surfaces in all groups increased in surface irregularity following STB. Clinical significanceWhilst finishing using a tungsten carbide finishing bur followed by either the Sof-Lex or PoGo polishing system may be found to result in a smooth surface finish, all the surfaces investigated increased in surface roughness following toothbrushing.

Influence of Filler Loading on the Mechanical Properties of Flowable Resin Composites.

The aim of this study was to evaluate the correlation between the percent of inorganic filler by weight (wt. %) and by volume (vol. %) of 11 flowable resin composites (FRCs) and their mechanical properties. To establish the correlation, the quantity of inorganic filler was determined by combustion and shape/size analyzed by SEM images. The compressive strength (CS), flexural strength (FS), and flexural modulus (FM) were determined. The CS values were between 182.87-310.38 MPa, the FS values ranged between 59.59 and 96.95 MPa, and the FM values were between 2.34 and 6.23 GPa. The percentage of inorganic filler registered values situated between 52.25 and 69.64 wt. % and 35.35 and 53.50 vol. %. There was a very good correlation between CS, FS, and FM vs. the inorganic filler by wt. % and vol. %. (R2 = 0.8899–0.9483). The highest regression was obtained for the FM values vs. vol. %. SEM images of the tested FRCs showed hybrid inorganic filler for Filtek Supreme XT (A3) and StarFlow (A2) and a homogeneous type of inorganic filler for the other investigated materials. All of the FS values were above 50 MPa, the ISO 4049/2019 limit for FRCs.

Effect of dental bleaching on the microhardness and surface roughness of sealed composite resins.

ObjectivesThe aim of this in vitro study was to evaluate the microhardness and surface roughness of composite resins before and after tooth bleaching procedures.Materials and MethodsSixty specimens were prepared of each composite resin (Filtek Supreme XT and Opallis), and BisCover LV surface sealant was applied to half of the specimens. Thirty enamel samples were obtained from the buccal and lingual surfaces of human molars for use as the control group. The surface roughness and microhardness were measured before and after bleaching procedures with 35% hydrogen peroxide or 16% carbamide (n = 10). Data were analyzed using 1-way analysis of variance and the Fisher test (α = 0.05).ResultsNeither hydrogen peroxide nor carbamide peroxide treatment significantly altered the hardness of the composite resins, regardless of surface sealant application; however, both treatments significantly decreased the hardness of the tooth samples (p < 0.05). The bleaching did not cause any change in surface roughness, with the exception of the unsealed Opallis composite resin and dental enamel, both of which displayed an increase in surface roughness after bleaching with carbamide peroxide (p < 0.05).ConclusionsThe microhardness and surface roughness of enamel and Opallis composite resin were influenced by bleaching procedures.

Shear bond strength to sound and caries-affected dentin of sim-plified “etch-and-rinse” and “self-etch” adhesives and the hybrid layer micromorphology

Background/Aim. After removal of caries-infected dentin, a considerable area of the cavity floor comprising caries- affected dentin. Bonding to caries-affected dentin is characterized by lower bound strength and inferior hybrid layer guality compared to bonding to sound dentin. The purpose of study was to compare shear bond strength (SBS) of currently available adhesive systems to sound dentin (SD) and caries-affected dentin (CAD) and elucidate the hybrid layer micromorphology. Methods. Sixty extracted human molars with coronal carious lesions formed the experimental sample while additional sixty extracted intact human molars (impacted third molars) served as controls. Identification of a carious-affected dentin was carried out using visual identification (North Carolina Dentin Sclerosis Scale). Teeth from both the experimental and the control sample were allocated to one of the following three groups: Adper Single Bond Plus/Filtek Supreme XT (ASB/FS) (3M ESPE), AdheSE One/Tetric EvoCeram (AO/TEC) (IvoclarVivadent), and Prime&amp;Bond NT/CeramX Mono (PB/CXM) (Dentsply). Bonding procedures utilized in this work were in line with the manufacturers? instructions. The SBS was measured using a universal testing apparatus. Hybrid layer micromorphology was observed under scanning electron microscope (SEM). The mean SBS values (MPa), and hybrid layer thickness (in ?m) were statistically analyzed using the t-test, Mann-Whitney U-test, ANOVA, and Holm?s test. Results. Mean SBS ? standard deviation were: ASB/FS to SD = 10.56 ? 3.49; ASB/FS to CAD = 10.06 ? 2.55; AO/TEC to SD = 7.01 ? 2.05; AO/TEC to CAD = 6.73 ? 1.66; PB/CXM to SD = 9.01 ? 2.47; PB/CXM to CAD = 7.83 ? 1.42. A statistically significant difference was found between the bonding strength of ASB/FS and AO/TEC to both SD and CAD, and between ASB/FS and PB/CXM to CAD. Hybrid layer thickness was statistically significantly greater for ASB/FS than for PB/CXM. For the ASB/FS system, a statistically significantly thicker hybrid layer was formed on CAD than on SD. No hybrid layer could be observed for AO/TEC. Conclusion. All tested compsite systems bond equally well on sound and caries-affected dentin. The etch-and-rinse adhesives achieved stronger bond strengths. The Adper single Bond Plus-Filtek Supreme XT system formed a statistically significantly thicker hybrid layer on both type 1 of dentin than the Primu 8 Bond NT-CeramX Mono system.

Mechanical and surface properties analysis of restorative materials submitted to erosive challenges in situ.

Objective:This study aims to evaluate the effect of acidic solutions (AS) on surface roughness (Ra) and microhardness of restorative materials (RM).Materials and Methods:Eight volunteers wore intraoral palatal devices (IPD) containing samples of RM: Ketac Nano (KN); Ketac Nano + Biscover LV (KN-B); Esthet-X (EX); Esthet-X + Biscover LV (EX-B); Supreme XT (SXT); Supreme XT + Biscover LV (SXT-B); and bovine enamel. The samples were submitted to three phases: (1) immersion in 0.01M hydrochloric acid (HCl) – 10 min, three times/day (14 days); (2) immersion in soft drink (Sprite®) – 10 min, three times/day (14 days); and (3) keeping in saliva (14 days). Changes in Ra/microhardness were measured before/after the three phases.Statistical Analysis:ANOVA (α = 0.05) and Fisher's test.Results:Materials sealed with Biscover LV (B) presented lowest values in all periods. KN glass ionomer cement showed highest Ra values after exposure in AS. Application of B did not reduce the Ra for the composites studied, except for EX after immersion in HCl. AS promoted changes in Ra/microhardness of RM, except for sealed materials.Conclusions:The acids used were able to change the Ra and microhardness of RM, except of the sealed materials. The resin-modified GIC showed the most significant changes after immersion in AS; and the composites sealed with B, even after immersion in acidic solutions (AS), showed the lowest Ra values and the least degradation in microhardness, especially when subjected to low pH solutions.

Effects of deformation rate variation on biaxial flexural properties of dental resin composites.

ObjectivesThis study aimed to determine the biaxial flexural strength (BFS) of resin composite materials at distinct deformation rates.MethodsTwo micro-hybrid [Filtek Z100™ Restorative (Z100), Filtek™ Z250 (Z250)] and two nano-filled [Filtek™ Supreme XT Body (FSB), Filtek™ Supreme Translucent (FST)] composite resins were selected. Disc-shaped (12 × 1 mm) specimens were fabricated using nylon split moulds. Bar-shaped specimens (25 × 2 × 2 mm) were fabricated from each material to determine the flexural modulus. The specimens were tested for BFS and flexural modulus under dry and wet conditions after 1, 13, and 52 weeks.ResultsThe highest BFS was recorded for Z250 (162 ± 19 MPa), followed by FST (154 ± 16 MPa), Z100 (150 ± 18 MPa), and FSB (136 ± 18 MPa). The materials exhibited a clear trend of increase in BFS with deformation rate. Following immersion for 1 week, the BFS was 126 ± 18 MPa for Z100, and 124 ± 17 MPa for Z250, which were higher than those of FSB (99 ± 16 MPa) and FST (115 ± 19 MPa) under comparable conditions. There was a remarkable reduction in the flexural moduli of the specimens immersed for 1 week compared to those of the dry specimens: Z100 (from 18.3 ± 1.2 GPa for dry specimen to 15.7 ± 0.8 GPa after immersion for 1 week), Z250 (from 16.7 ± 0.8 GPa to 13.3 ± 1.4 GPa), FSB (from 13.7 ± 0.6 GPa to 11.0 ± 2.1 GPa) and FST (from 12.7 ± 2.3 GPa to 10.4 ± 1.0 GPa).ConclusionThis study concludes that the BFS and flexural moduli of resin-based dental restoratives decline when they are immersed in an aqueous medium until saturation with water. However, after equilibrium is established, the immersion medium does not affect the restorative materials further. Variations in deformation rate did not have a significant effect on the BFS of resin-based dental restoratives.

The effect of different finishing and polishing techniques on surface roughness and gloss of two nanocomposites

ObjectivesThe aim of this in vitro study was to evaluate the effect of four finishing and polishing protocols in Surface Roughness (Ra) and Surface Gloss (Ga) of two different nanocomposites. Materials and MethodsIn total, 50 disc samples of a nanofilled resin and a nanohybrid resin were prepared. The samples were assigned randomly to one of the five groups to which different polishing protocols were applied. Analysis of surface roughness was performed using an Atomic Force Microscope (AFM), with the gloss evaluated using a gloss meter.Statistical evaluation of the results were analyzed using SPSS software, based on one-way ANOVA parametric tests along with the Welch correction and the Dunnett test for multiple comparisons of the tested protocols. ResultsThe results evidence the significant influence of the applied Protocol Types and Resin Types on Surface Roughness (Ra) and Surface Gloss (Ga). The multiple comparisons between polishing systems highlight the contrast between the most complex protocol, evidencing the lowest average Ra and the highest value Ga, and control protocol, evidencing the highest average Ra and the lowest percentage Ga. Filtek™ Supreme XT provided the best results in both Ra and Ga, in Protocol 4, while Brilliant Everglow™ performed better in Protocols 2 and 3. ConclusionsBoth Ra and Ga are dependent on the type of protocol used, as protocol 4 evidence a higher performance, depending also on the type of resins tested in the research, as nanofilled resin provided the best results. Furthermore, the gloss is influenced significantly by the surface roughness of the composite resin. Clinical RelevanceIn order to achieve excellent aesthetic appearance and high durability of the direct restoration, it is important to select initially the appropriate biomaterial for use and then to base preference for a polishing technique on achieving perfect results in the surface texture.

TEGDMA and UDMA monomers released from composite dental material polymerized with diode and halogen lamps.

More than 35 substances released from composite fillings have been identified. Among these, basic monomers and the so-called co-monomers are most often reported. The substances released from polymer-based materials demonstrate allergenic, cytotoxic, genotoxic, mutagenic, embryotoxic, teratogenic, and estrogenic properties. The aim of this study was to measure the amounts of triethylene glycol dimethacrylate (TEGDMA) and urethane dimethacrylate (UDMA) monomers released from composite dental fillings to citrate-phosphate buffer with the pH of 4, 6, 8 after 24 h and 6 months from the polymerization. Ten samples for each polymerization method had been made from the composite material (Filtek Supreme XT, 3M ESPE, St. Paul, USA), which underwent polymerization using the following lamps: halogen lamp (Translux CL, Heraeus Kulzer, Hanau, Germany) (sample H) and diode lamp (Elipar Freelight 2, 3M ESPE), with soft start function (group DS) and without that function (group DWS). It has been demonstrated that the type of light-curing units has a significant impact on the amount of TEGDMA and UDMA released. The amount of UDMA and TEGDMA monomers released from composite fillings differed significantly depending on the source of polymerization applied, as well as the pH of the solution and sample storage time. Elution of the monomers from composite material polymerized using halogen lamp was significantly greater as compared to curing with diode lamps.

Silorane Based Resin Composite Versus Nanohybrid Resin Composite: Effect of pH of Storage Media on Volumetric Changes and Adaptability at Tooth/Restoration Interface

This study compared dimensional stability and adaptability of two resin composites [Filtek P90 and Filtek Supreme XT] after storage in different pH media. Methods: For dimensional stability, cylindrical specimens were prepared either from Filtek P90 or Filtek Supreme XT. Specimens’ dimensions were measured before and after storage in neutral [pH7] or acidic saliva [pH 3.6] for 1 week, 1month or 3 months. Volumetric changes were calculated. For adaptability, 80 class V cavities were made in sound human teeth. The cavities were restored with Filtek P90 or Filtek supreme XT. The adaptation was evaluated using stereomicroscope; before and after storage in acidic or neutral saliva for 1 week,1 or 3 months. Results: Filtek P90 showed significantly higher contraction compared to Filtek Supreme XT only after 3 months storage. After 1 week or 1 month, the difference in volumetric changes between two material was statistically non-significant. The pH of storage media showed non-significant effect on volumetric changes of both composites. For adaptability to cavity walls in acidic saliva, no statistically significant difference was found between gap dimensions at tooth restoration interface for both Filtek P90 and Filtek Supreme XT. However, in neutral saliva, Filtek P90 showed statistically significantly higher mean gap dimensions than Filtek Supreme XT through all time storage. Conclusions: Silorane-based resin composite undergoes volumetric changes comparable to nanohybrid resin composite except on long term storage where it revealed contraction. The adaptation of silorane based composite was worse compared to that of nanohybrid composite in neutral pH media.

EFFECT OF LASER ETCHING ON BONDING AND DEBONDING OF ORTHODONTIC BRACKETSE

Objectives: Comparing effect of surface enamel conditioning when irradiated with Er,Cr:YSGG laser versus typical phosphoric acid etching on shear bond strength of orthodontic brackets and their effect on esthetics of enamel surfaces after debonding. Methods: Forty freshly extracted premolars were used in this study. Sample was divided into two groups (n=20), group I; enamel etched with 37% phosphoric acid (3M Unitek, Monrovia, USA) for 15 s. Group II; enamel was irradiated with Er,Cr:YSGG laser ablated with an energy output of 4.5 watt/20hz (2.78 μm wavelength) used for 15 sec. Orthodontic brackets (NU-EDGE.022” ROTH RX.TP orthodontics) were bonded to enamel surface of all specimens (Feltik Supreme XT Flowable, 3M/ESPE). The teeth were placed in Lloyd universal testing machine at crosshead speed of 0.5 mm/minute, and the shear force to remove the brackets was recorded. The bracket bases and enamel surfaces were examined after debonding under a light stereomicroscope at 20 x magnification and the adhesive remnant index (ARI) scores were assigned to each specimen. Statistical analysis was conducted using SPSS. The SBS data were compared with an unpaired t test. Statistical significance for both tests was defined as p < 0.05. The distributions of ARI scores were compared with an unpaired t test. Results: A higher shear bond strength mean value was recorded in acid etching group (14.71±0.82) Mpa, where unpaired t test revealed that the difference between groups was statistically significant (P<0.0001). Higher (ARI) mean value was recorded in laser etching group (2.3±0.47), where unpaired t test revealed that the difference between groups was statistically significant (P<0.0001). Conclusions: Er:YAG laser is capable of obtaining optimal bond strength for orthodontic brackets when used as a surface conditioning agent though have lower bond strength, In addition, it leaves the enamel with a rougher surface upon debonding versus typical acid etching techniques.