Composite Resin Systems Research Articles

THE EFFECT OF RELATIVE ENAMEL/DENTIN SHADE THICKNESS ON THE COLOR OUTCOME OF RESIN COMPOSITE SYSTEMS

This study was conducted to evaluate the effect of relative thickness of different resin com­posite systems using enamel and dentin shades following the natural layering concept on the final color outcome. Ninety resin composite discs were assigned according to resin composite system into three groups of 30 discs each: Ceram X Duo (S1), Filtek™ Z350 XT (S2) and Amaris® (S3). Each group was divided in to 3 subgroups (n=10) according to the relative Enamel (E) : Dentin (D) thickness in to 0.5mm E: 1.5mm D (T1), 1 E: 1 D (T2), 1.5 E:0.5 D (T3) on top of 0.5mm thick basic enamel background as a standardized layer simulating the clinical condition. A Vitapan A2 classical shade tab was used as a reference shade to which the different specimens of the three tested systems were compared. Color difference (ΔE) was measured and calculated using an electronic shade detection device which is VITA Easyshade® Advance 4.0 over a black background. UV-Shimadzu 3101 pc-spectrophotometer was also used in this study to confirm the results obtained by Easyshade Advance 4.0. The results were analyzed by analysis of variance (ANOVA)/Tukey’s post hoc test (p < 0.05) ΔE. All tested composite systems at all thickness showed significant color differ­ence (ΔE) when compared to each other with the increase of the enamel shade thickness. Although the ΔE between S2T1 and A2 shade tab was statistically significant, but clinically not perceptible (ΔE=1.780 ± 0.1814).

Evaluation of Surface Roughness of Ceramic and Resin Composite Material Used for Conservative Indirect Restorations, after Repolishing by Intraoral Means.

To evaluate and compare the mean surface roughness (Ra) of one ceramic and one resin composite material used for indirect restorations, after grinding and repolishing by intraoral means. The materials used were the lithium disilicate glass ceramic IPS e.max Press (EMP) and the indirect resin composite restoration system Gradia (GR). Twelve specimen disks were prepared from each material according to the manufacturer of each material. Five initial measurements of the Ra (Ra1 ) were made on each specimen as a referral basis, and the specimens were ground with a fine (red) diamond bur. The specimens were repolished using (a) Komet Dialite Polishing Kit for EMP and (b) Enhance Finishing and Polishing System and Prisma Gloss Polishing Paste for GR. Five final Ra (Ra2 ) measurements were performed on each specimen. All measurements were made using a laser profilometer. Scanning electron microscopy (SEM) was also used to visualize the initial surface morphology and the morphological changes on the specimens' surface after repolishing. A highly significant difference was found between Ra1EMP and Ra2EMP (p < 0.001), between Ra1GR and Ra2GR (p < 0.001), as well as between Ra2EMP and Ra2GR (p < 0.001), when compared in pairs. A highly significant difference (p < 0.001) was also found between ΔRaEMP and ΔRaGR , with ΔRaGR being higher than ΔRaEMP . The RaGR values were higher than the RaEMP values at all times. SEM revealed that both EMP and GR repolished surfaces presented with irregularities; however, in GR specimens major voids and craters were present. EMP was found to perform better when polished by intraoral means compared with GR. Both materials exhibited Ra2 above the critical threshold for increased plaque accumulation and periodontal inflammation. If enamel-to-enamel roughness found in occlusal contact areas is considered as baseline, both materials were clinically acceptable after repolishing.

Effect of Restorative System and Thermal Cycling on the Tooth-Restoration Interface - OCT Evaluation.

The present study evaluated the tooth/noncarious cervical lesion restoration interface when using different adhesive systems and resin composites, submitted to thermal cycling (TC), using optical coherence tomography (OCT). Noncarious cervical lesion (NCCL) preparations (0.7 mm depth × 2 mm diameter) were performed on 60 human third molars and randomly divided into six groups, according to the adhesive system and resin composite used: group 1 = Adper Single Bond 2 (SB2) + Aelite LS Posterior (AP); group 2 = SB2 + Venus Diamond (VD); group = SB2 + Filtek Z250XT (Z250); group 4 = Clearfil SE Bond (CSE) + AP; group 5 = CSE + VD; group 6 = CSE + Z250. Selective enamel etching was performed for 30 seconds on groups 4, 5, and 6, while groups 1, 2, and 3 were etched for 30 seconds in enamel and 15 seconds in dentin. All groups were evaluated using OCT before and after TC (n=10). Images were analyzed using Image J software; enamel and dentin margins were separately evaluated. Data from OCT were submitted to PROC MIXED for repeated measurements and Tukey Kramer test (α = 0.05). No marginal gaps were observed in etched enamel, either before or after TC, for all adhesive and resin composite systems. A significant interaction was found between adhesive system and TC for the dentin groups; after TC, restorations with CSE showed smaller gaps at the dentin/restoration interface compared with SB2 for all resin composites. Increased gap percentages were noticed after TC compared with the gaps before TC for all groups. In conclusion, TC affected marginal integrity only in dentin margins, whereas etched enamel margins remained stable even after TC. Dentin margins restored with CSE adhesive system showed better marginal adaptation than those restored with SB2. Resin composites did not influence marginal integrity of NCCL restorations.

Bond degradation resistance of self adhesive sealer bonded to radicular dentin using an alternative adhesive strategy

ObjectiveThis study was carried out to evaluate the effect of an alternative adhesive strategy; double layering dentin bonding procedure in root canal obturation on the durability of root canal sealing using Resilon/Epiphany dual cure resin composite sealer system. Materials and methodsOne hundred and twenty freshly extracted human upper central incisors teeth with straight root canals were used. The crowns were removed at the level of Cemento-Enamel Junction (CEJ). All roots were instrumented with a crown-down technique. The root canals were filled with either single or double layering bonding techniques, aged for 7 days and 3 months, and then sectioned perpendicular to the longitudinal axis of each root into a series of 1.0 mm thick cross-sectional slices. Durability of sealing was tested by both micropush out and nanoleakage tests. For the micropush out test, each root slice was subjected to compressive loading via a computer controlled materials testing machine, while for nanoleakage, the slices were immersed in the tracing solution of ammoniacal silver nitrate for 24 h in complete darkness. Photomicrographs were obtained by Environmental Scanning Electron Microscope. ResultsThe micropush out bond strength increased significantly with the double layering technique. On the other hand, it was not affected by aging. Only one nanoleakage pattern start to emerge as early as 7 days after sealing and continue after that. ConclusionsThe current study supports the concept that double layering bonding strategy might be successfully adapted to endodontics to optimize bond strength of endodontic self-adhesive sealers to radicular dentin and to reduce nanoleakage.

Cylindrical conformal single-patch microstrip antennas based on three dimensional woven glass fiber/epoxy resin composites

Three dimensional integrated microstrip antenna (3DIMA) can carry the designed load while functioning as an antenna. In this study, the cylindrical conformal single-patch 3DIMAs with various curvatures were designed, simulated, fabricated and tested experimentally using a 3D orthogonal woven glass preform/epoxy resin composite system. The electromagnetic performances of the cylindrical microstrip antennas were analyzed. The simulated and tested results matched well and the return losses of the cylindrical conformal 3DIMAs with radii of curvatures of 60, 45 and 25 mm were less than −10 dB while resonant frequencies and their gain values were significantly influenced by the radius of curvature and the feeding direction. The 3DIMAs with the curvature perpendicular to the feeding directions showed more stable resonant frequencies and larger gain values than those of 3DIMAs with the curvature along their feeding directions.

Effect of silorane-based adhesive system on bond strength between composite and dentin substrate.

Context:The complexities of the oral environment, the dentin substrate, and the different bond and composite resin systems represent a challenge to the maintenance of reasonable bond between the composite resin and the tooth structure.Aims:To evaluate the effect of the adhesive system on bond strength between silorane-based composite resin and dentin.Materials and Methods:Fourteen human molars extracted were selected and vertically cut into 3 dentin fragments, randomly divided among the experimental groups and restored with Z250 and P90 composite resin using different adhesive protocols (Adper Single Bond 2, Silorano primer, Adper SE Plus, and Scotchbond Multiuse). Two composite resin cylinders were built up on each dentin surface (n = 10) and subjected to a micro-shear bond strength test.Statistical Analysis Used:Kruskal–Wallis one-way analysis of variance and Tukey test (P = 0.05).Results:According to the results, Kruskal–Wallis test evidenced at least one statistical significant difference (P = 0.001). The Tukey test showed statistically significant differences among the group (P < 0.05). Group PSM8 (P90 + SM) showed statically significant higher results when compared with groups PSP4 (P90 + SP), PSB2 (P90 + SB), and ZSE5 (Z250 + SE).Conclusion:The results evidenced that the monomer of the adhesive system has an effect on bond strength between the composite resin and dentin.

One-year evaluation of two hybrid composites placed in a randomized-controlled clinical trial

ObjectiveThe aim of this prospective randomized-controlled clinical trial is to assess the long-term performance of two direct composite resins in posterior teeth. This study provides a survey of the one-year results. Materials and methodsA total of 1805 restorations were placed by students in stress-bearing Class I/II cavities (including cuspal-coverage) in molars and premolars in 456 patients. Clinical evaluation was performed at baseline and after one year using modified USPHS criteria. The restorations in each patient were performed either with Ceram X/Prime&Bond NT or Tetric Ceram/Optibond Solo Plus. ResultsAfter one year 528 fillings with Ceram X and 580 with Tetric Ceram were available for evaluation of substance loss, contact point, color match, marginal staining, marginal adaptation, secondary caries and radiographic examination (if necessary). This represents a recall rate of 61.18% (279 patients). The failure rate per material was 5.3% in the Ceram X group and 6.1% in the Tetric Ceram group. Most of the failures were associated with marginal adaptation/integrity of the filling. A significant influence on the occurrence of a failure was observed for the number of treated teeth per patient, the age of the patient, the mesio-distal extension of the restoration and the tooth position. Gender, material, a previous root canal treatment, the bucco-lingual extension of the filling or cuspal-coverage did not significantly influence the failure rate. Patients attending the first recall were significantly older and had more fillings than patients not attending. ConclusionsIn a group of Class I/II restorations (including cuspal-coverage), there was no significant difference in failure rates between ormocer-based and bis-GMA-based restorative systems after one year. A previous root canal treatment had no negative influence on the failure rate. A longer observation period is indicated to get clear evidence of the long-term performance of these composite resin systems.

Roughness and microstructural changes in Y-TZP laser treated before sintering

Purpose: The purpose of this work was to qualitatively assess the actual failure origin (bonded dentin interface or loaded resin cylinder surface) during shear bond testing, by scaling and fracture surface analysis. Failure behavior was assessedbyexamining scaling effects on failure loadsbybonding surface area (by r2) and bonded resin cylinder surface area (by r) with increasing r. Methods and materials: Non-carious human molar teeth were stored in 0.3% sodium azide solution. Nine 2-mm thick dental disks from the occlusal dentin were prepared using a low-speed sectioning saw and stabilized in a 1′′-dia. cold-cure acrylic resin. The tooth disks were prepared as instructed for the resin composite system (Filtek TM Supreme Ultra) and one of four resin composite cylinders (1.59mm, 3.18mm, 4.76mm, 6.35mm dia., all 5-mm in length) were bonded on the prepared tooth surface. Specimens were stored in saline for 1-day prior to testing. The samples were then shear tested at room temperature using an Ultratester testing machine (Ultradent Products) at a 1.0mm/min crosshead speed (5mm long square piston). Following shear testing, each dentin disk was finished with silicone carbide paper (240–600 grit) to remove any residual resin composite debris and tested again with the same resin composite of a different diameter cylinder, until each disk was tested with all four different diameter cylinders (all diameters used in each cycle). If failure involved the bonded surface area or the surface area of the loaded cylinder (contact stress between flat and cylinder), one of the following relationships would be constant with increasing radii (r): For bonded area?r/L?2 = 1/ps= constant; For cylinder surface r/L=2/psbl = constant where b=KvL and K= [2/pl ((1−v 12)/E 1+ (1−v 22)/E 2)/((1/d 1) + (1/d 2))](1/2) With: L= load l = cylinder length v1 and v2=Poisson’s ratios E1 and E2=elastic moduli d1 and d2=diameter of cylinder and flat (=8) [so K∼ 1/[pl(1/2r)]. Results: The relationship for the cylinder surface area was constant while the relationship for the bonded surface area was not. In addition, failure loads scaled linearly with r (r2 = 0.99, p=0.004) and not with r2. Fractographic analysis (SEM) is consistent with failures occurring from the loaded cylinder, not the bonded interface. Conclusion: “Shear bond” testing does not appear to test the bonded interface. http://dx.doi.org/10.1016/j.dental.2014.08.024

Short Fiber Reinforced Composite: a New Alternative for Direct Onlay Restorations

Objectives: To determine the static load-bearing capacity of direct composite onlay restorations made of novel filling composite resin system which combines short fiber-reinforced composite resin (FC) and conventional particulate filler composite resin (PFC).Methods: Three groups of onlay restorations were fabricated (n = 8/group); Group A: made from conventional particulate filler composite resin (Z250, 3M-ESPE, USA, control), Group B: made from short fiber-reinforced composite resin (EverX posterior, StickTeck Ltd, member of GC group, Turku, Finland) as substructure with 1 mm surface layer of PFC, Group C: made from FC composite resin. The specimens were incrementally polymerized with a hand-light curing unit for 80 s before they were statically loaded with two different sizes (3 & 6 mm) of steel ball until fracture. Failure modes were visually examined. Data were analyzed using ANOVA (p = 0.05).Results:ANOVA revealed that onlay restorations made from FC composite resin had statistically significantly higher load-bearing capacity (1733 N) ( p < 0.05) than the control PFC composite resin (1081 N). Onlays made of FC composite resin with a surface layer of PFC gave force values of 1405 N which was statistically higher than control group ( p < 0.05). No statistically significant difference was found in the load-bearing capacity between groups loaded by different ball sizesSignificance: Onlay restorations combining base of short fiber reinforced composite resin as substructure and surface layer of conventional composite resin displayed promising performance in high load bearing areas.

Effect of different configuration factors on marginal gap formation of two composite resin systems

AimTo evaluate the effect of different configuration factors “C-factors” on the marginal gap formation of two types of contemporary composite resin systems before and after thermal loading. Materials and methodsOne hundred and twenty eight human sound molars were used. The occlusal surface of each tooth was wet-ground until flat dentin surfaces were obtained. Teeth were divided into four main groups in which cylindrical cavities were prepared representing different C-factors. Samples in each group were subdivided into 2 subgroups according to the type of composite resin system. The cavities in subgroup A were restored with Clearfil SE bond and Clearfil Majesty Esthetic while those in subgroup B were restored with Futurabond DC and Grandio SO. Eight samples in each subgroup were thermo-cycled. All samples were processed for SEM evaluation to examine the restoration margins at (25× and 500×) magnification. The marginal gap was measured for all the samples using AutoCAD software. ResultsThe median values (IQR) of the marginal gap were 0 (0) in all the samples restored with Clearfil Majesty Esthetic. The same was found in samples restored with Grandio SO which were not subjected to thermo-cycling, while those subjected to thermo-cycling, a direct relation was found between C-factor and gap length. Thermo-cycling had a significant effect on marginal gap particularly in samples restored with Grandio SO with high C-factor preparations. The two tested composite resin systems had a significant effect on the marginal gap particularly in high C-factor preparations. The C-factor had no significant effect on the marginal gap except in samples restored with Grandio SO. ConclusionThe different C-factors had no effect on the marginal gap formation in the samples of both subgroups which were not subjected to thermo-cycling but could influence the marginal gap formation in the samples restored with Grandio SO subjected to thermo-cycling.

Influence of Different Post-Core Systems on Impact Stress: a Pilot Study

This pilot study compared impact strain at the core and root surfaces between two different post-core systems. Materials and Methods: The form of a bovine mandibular front tooth was modified to resemble that of a human maxillary incisor as a test specimen. A cast post and core (Metal PC) and composite resin and glass fiber-reinforced epoxy resin post (Fiber-Resin PC) system were tested. Four gauges were affixed to the buccal and lingual surfaces of the core and root. The specimens were then embedded in a metal mold using dental stone. A pendulum-type device with a pyramid-shaped metal impact object with a titanium alloy head was used to provide 2 different shock forces. Maximum distortion was measured and analyzed. Results: Distortion at the core at each measurement point and total amount of distortion with Fiber-Resin PC was significantly greater (p<0.05) than that with Metal PC against both impact forces. On the other hand, distortion at the root at the buccal measurement point with Fiber-Resin PC was significantly less than that with Metal PC against both impact forces. Total distortion was significantly less with Fiber-Resin PC than that with Metal PC against the greater impact shock. Acceleration with Fiber-Resin PC was significantly less than that with Metal PC against both impact forces. Conclusion: Fiber-Resin PC has the potential to protect remaining root against traumatic force. This suggests that a Fiber-Resin PC is more suitable for non-vital teeth against not only occlusal but also traumatic impact force.

5-Year Clinical Performance of Resin Composite versus Resin Modified Glass Ionomer Restorative System in Non-Carious Cervical Lesions

Clinical Relevance A long-term evaluation of the materials' behavior is relevant for Class V restorations in which clinical performance is particularly challenging.

Bonding performance of a newly developed step-less all-in-one system on dentin

The purpose of this study was to evaluate the short-term µTBS (Micro-tensile bond strength) and microscopic (SEM and TEM) observation of four recent adhesives. One adhesive was an experimental step-less 1-step system (LLB-2, Tokuyama Dental), which is an all-in-one system without the light-curing step in the application process. The other two were self-adhering light-cured flowable composite resin systems FLD (Fusio Liquid Dentin, Pentron Clinical Technologies) and VF (Vertise Flow Dental Restorative Materials, Kerr Corporation), which combine all the bonding steps together. A 2-step self-etching system MG (Clearfil MegaBond, Kuarary Medical) was employed as the control group in this study. The µTBS of MG was the highest (79.0 MPa) followed by that of LLB-2 (63.1 MPa), FLD (23.6 MPa), and VF (13.1 MPa). The microscopic observations showed that MG and LLB-2 had an approximately 20 µm and 5 µm adhesive layer respectively, without bubble or gap-formation at the resin-dentin interface, which were found in FLD and VF.

Three-year clinical performance of two indirect composite inlays compared to direct composite restorations

Objective: Despite the incremental build-up of resin composite restorations, their polymerization shrinkage during curing presents a serious problem. Indirect composite resin systems represent an alternative in overcoming some of the deficiencies of direct composite restorations. The hypothesis of the present study states that the clinical performance of restorations may be affected by different generation and application techniques. Study Design: Sixty restorations (20 DI system (Coltène/Whaledent AG, Altstätten, Switzerland) composite inlays, 20 Tescera ATL system (BISCO Inc. Schaumburg, Illinois, USA) composite inlays, and 20 direct composites) were applied to premolar teeth in 49 patients. Restorations were clinically evaluated by two examiners. Data were analyzed using the Kruskal-Wallis, Mann-Whitney U, Wilcoxon Signed Ranks, and X2 tests. Results: The Tescera ATL system performed significantly better than both direct composite restorations (p<0.001) and DI system (p<0.05). Conclusion: Within the limitations of this 3-year clinical study, indirect resin restorations showed better scores than direct restorations. In addition, the Tescera ATL system was found to be more successful than the DI system and direct composite restorations. Key words:Composite, inlay, direct composite restorations, indirect composite restorations.

Temperature Rise during Primer, Adhesive, and Composite Resin Photopolymerization of a Low-Shrinkage Composite Resin under Caries-Like Dentin Lesions

Objective. This study evaluated temperature rise of low-shrinkage (LS) self-etch primer (P), LS self-etch adhesive (A), and P90 silorane-based composite resin systems, photopolymerized under normal and artificially demineralized dentin. Methods. Forty 1.5 mm-thick dentin discs were prepared from sound human molars, half of which were demineralized. Temperature rise was measured during photopolymerization using a K-type thermocouple under the discs: 10 s and 40 s irradiation of the discs (controls/groups 1 and 2); 10 s irradiation of primer (P), 10 s irradiation of adhesive (A), 40 s irradiation of P90 without P and A, and 40 s irradiation of P90 with P and A (groups 3 to 6, resp.). The samples were photopolymerized using an LED unit under 550 mW/cm2 light intensity. Data was analyzed using repeated measures ANOVA and paired-sample t-test (α = 0.05). Results. There were no significant differences in temperature rise means between the two dentin samples for each irradiation duration (P > 0.0001), with significant differences between the two irradiation durations (P > 0.0001). Temperature rise measured with 40 s irradiation was significantly higher than that of 10 s duration for undemineralized and demineralized dentin P < 0.0001). Conclusions. Light polymerization of P90 low-shrinkage composite resin resulted in temperature rise approaching threshold value under artificially demineralized and undemineralized dentin.

Preliminary Clinical Evaluation of Short Fiber-Reinforced Composite Resin in Posterior Teeth: 12-Months Report

This preliminary clinical trial evaluated 12 month clinical performance of novel filling composite resin system which combines short fiber-reinforced composite resin and conventional particulate filler composite resin in high stress bearing applications. A total of 37 class I and II restorations (compound and complex type) were placed in 6 premolars and 31 molars. The restorations were reviewed clinically at 6 months (baseline) and 12 months using modified USPHS codes change criteria for marginal adaptation, post-operative sensitivity, pulpal pain and secondary caries criteria. Photographs and x-rays were obtained for restorative analysis. Results of 12 months evaluation showed 5 restorations having little marginal leakage (B score) and 1 patient had minor pulpal symptom and post-operative sensitivity (B score). No secondary caries or bulk fracture was detected. The majority of restorations exhibited A scores of the evaluated criteria. After 12 months, restorations combining base of short fiber reinforced composite resin as substructure and surface layer of hybrid composite resin displayed promising performance in high load bearing areas.

Nanofilled Composite Restorations with Different Adhesives Strategies: Clinical Cases

The esthetic procedures with composites are widely applied, both to posterior and anterior teeth to restore caries cavities, to replace failed restorations, or to make cosmetic procedures. The materials selected to each case may make the difference in the clinical result. This paper presents two clinical cases made with a nanofilled composite resin system used in different bond strategies. In the first, a wide posterior class I restoration, the self-etching strategy was used. The second, an esthetic anterior restoration, was made using the prior etching with phosphoric acid and a hydrophobic adhesive.

Mechanical and thermal properties of (Ag/C nanocable)/epoxy resin composites

A novel Ag/C nanocable and epoxy resin composite was obtained by compounding Ag/C nanocables and epoxy resin. The nanocable is composed of a nanowire (core) wrapped with one or more outer layers (shell). Scanning electron microscopy images proved that the nanocables consisted of a silver nanowire core and a carbon outer shell. The Ag/C nanocables were modified by hyperbranched poly (amine ester) to improve their mechanical properties for further application. We separately compounded raw and modified Ag/C nanocables with epoxy resin, and then tested the thermal performance, tensile properties, and fracture morphology of each composite. We found that the tensile strengths of the two composite systems were enhanced by the epoxy resin, with the modified (Ag/C)/epoxy resin composite system improving more significantly. Differential scanning calorimeter (DSC) results showed that the glass transition temperature of the unmodified (Ag/C)/epoxy resin composite is increased when the Ag/C nanocable is filled, while that of the modified system slightly decreased. Fracture morphology results showed that both (Ag/C)/epoxy composite systems featured increased toughness. The modified Ag/C nanocables had better compatibility with the epoxy resin. The relationship between the properties and microstructure of the composites were discussed in detail to explain the mechanism behind the observed changes in material properties.

Polymerization shrinkage/stress and dentin bond strength of silorane and dimethacrylate‐based dental composites

AbstractThis study was designed to determine whether a new dedicated adhesive system using a silorane composite exhibits better bonding performance to human dentin than conventional dimethacrylate‐based composites. The materials were used included: Adper™ Easy Bond‐Z250 (AE‐Z250), iBond‐Venus (IB‐VE), XenoIII‐TPH (XE‐TPH), Clearfil S3‐Clearfil Majesty (S3‐CM), and the Filtek silorane system (SA‐FS). Polymerization volumetric shrinkage and stress development were measured using a micro‐CT instrument and universal testing machine. The push out strength of the bonds produced using the corresponding self‐etching adhesive systems were also measured. The volumetric shrinkage of the resin composite/adhesive combinations ranged from 1.05% (SA‐FS) to 3.38% (XE‐TPH) 30 min after light curing. SA‐FS had the lowest volumetric shrinkage (P &lt; 0.05), followed by S3‐CM, EA‐Z250, IB‐VE, and XE‐TPH. The polymerization stress of the materials ranged from 1.54 (SA‐FS) to 3.49 MPa (S3‐CM). The lowest stress was also observed in SA‐FS at 30 min during the stress test (P &lt; 0.05). Push‐out bond strength testing revealed that IB‐VE had significantly lower bond strength than other combinations (P &lt; 0.05). The silorane composite and dedicated adhesive system exhibited excellent characteristics of low volumetric shrinkage and stress development compared to conventional dimethacrylate‐based composites. However, the silorane composite resin system possessed similar push‐out bond strength as the other materials, with the exception of the Venus/iBond combination. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Marginal analysis of resin composite restorative systems using optical coherence tomography

Objectives To analyze marginal integrity of resin composites dental restorations using optical coherence tomography (OCT). Methods Thirty extracted human premolars had occlusal cavities prepared and were randomly divided according to the restorative systems evaluated: Filtek P90™/P90 Adhesive System™, Filtek Z350™, and Filtek Z250™/Single Bond™ (3 M/ESPE). The teeth were then stored in the dark for 24 h in 0.9% saline solution. Restorations were finished and polished and stored again for 24 h before thermocycling (500 cycles, 5–55 °C). A commercially available OCT system was used (SR-OCT: OCP930SR/Thorlabs) with 930 nm central wavelength. Cross-sectional images were obtained every 250 μm and evaluated using Image J. A-scans were analyzed using the Origin 8.0 program, after a filter treatment using Matlab. Results The qualitative analysis of the internal margins did not observe gaps even after A-scan examination, although distinctive patterns were found for each restorative system. Penetration of Single Bond and Filtek P90 self-etch primer into dentin was also observed. A thick adhesive layer was found for Filtek P90 bonding agent. Significance Considering the characteristics of the OCT system, the setup used in this study was capable of evaluating the marginal integrity of resin composite restorations and detecting some interaction between dental bonding agents and dental substrates. OCT can be considered a promising method for the evaluation of the internal margins of restorations in vivo.