Effect of Scotchbond dependent on cavity cleaning, cavity diameter and cavosurface angle

Abstract – The effect of Scotchbond on the wall-to-wall polymerization contraction of a visible light activated microfilled resin was investigated in cavities prepared in extracted human teeth. The cavities were cleaned either with water spray or a saturated acidic solution of EDTA, the latter giving significantly better results. The cavities were prepared with cavosurface angles between 90° and 160°. A highly significant improvement of marginal adaptation was found with increasing cavosurface angle.     

Effect of Scotchbond dependent on cavity cleaning, cavity diameter and cavosurface angle

The effect of Scotchbond on the wall-to-wall polymerization contraction of a visible light activated microfilled resin was investigated in cavities prepared in extracted human teeth. The cavities were cleaned either with water spray or a saturated acidic solution of EDTA, the latter giving significantly better results. The cavities were prepared with cavosurface angles between 90 degrees and 160 degrees. A highly significant improvement of marginal adaptation was found with increasing cavosurface angle.     

Setting characteristics and cavity adaptation of low-shrinking resin composites

ObjectivesThe aim of this study was to evaluate the setting characteristics of low-shrinking resin composites and examine the possible interactions with curing efficiency and marginal adaptation in dentin cavities.MethodsThe materials tested were Ceram X Mono/CM, Premise/PR, Clearfil Majesty/CM, ELS/EL, and Filtek Silorane/FS. Polymerization shrinkage strain (%S), strain rate (%S_r) and time at maximum strain rate (t_max) were measured using the bonded disk method. Curing efficiency was measured on the top and bottom surfaces of composites with ATR-FTIR spectroscopy. Marginal adaptation was measured in unbonded (%VVF) and bonded (%XVF) specimens by computerized X-ray microtomography (micro-XCT). The % linear length of the interfacial gaps along the cavity margins (%LD) and the maximum gap width (WD_max) were calculated under optical microscopy on sectioned specimens. Statistical analysis was performed with one- and two-way ANOVA, Bonferroni's post hoc test and Pearson's correlation coefficient.ResultsThe %S values ranged from 1.34% (FS) to 2.29% (CX), while %S_r ranged from 0.06%s^?1 (FS) to 0.15%s^?1 (CX). %VVF values extended from 1.9% (FS) to 5.3% (CX) and for %XVF from 1.98% (FS) to 3.35% (CX). The values for %LD ranged from 36.52% (FS) to 81.28% (CX). Linear regression showed strong positive correlation for %S_r and t_max with %VVF (r² = 0.884 and r² = 0.927) and also for %S_r and t_max with %LD (r² = 0.823 and r² = 0.869).Significance%S_r and t_max are more representative than %S in determining the setting pattern of the materials and are strongly correlated to marginal adaptation. The silorane material showed better behavior than the dimethacrylate materials in setting shrinkage and marginal adaptation.     

Effect of five adhesives on adaptation of resin in dentin cavities

Cylindric dentin cavities ranging from 2 to 6 mm in diameter were treated with different dentin adhesives: Clearfil, Gluma, NPG-GMA + PMDM, Scotchbond or Superbond before filling with Silux. The maximal contraction gap was measured 10 min after curing and compared with result from cavities where an adhesive was omitted. The effectiveness in reducing contraction gaps increased in the following order: Clearfil, Scotchbond, NPG-GMA+PMDM, Superbond and Gluma.     

Effect of three dentin adhesives on marginal adaptation of two light-cured composites

The marginal adaptation of two light-cured composites, Silux and P-30, was tested in butt-joint dentin cavities prepared in extracted human teeth. The cavity diameter ranged from 1.8 mm to 6.3 mm. Only minor differences were found between the marginal contraction gap of Silux and P-30 when used without previous application of a dentin adhesive. The lightcured Scotchbond proved to be as effective as GLUMA in reducing the contraction gaps of Silux providing the smear-layer was partly removed, the adhesive polymerized for 50 s and finally wetted with Silux Enamel Bond prior to application of Silux. Both adhesives had markedly less effect on the contraction gaps of the highly filled P-30.     

Effect of three dentin adhesives on marginal adaptation of two light-cured composites

The marginal adaptation of two light-cured composites, Silux and P-30, was tested in butt-joint dentin cavities prepared in extracted human teeth. The cavity diameter ranged from 1.8 mm to 6.3 mm. Only minor differences were found between the marginal contraction gap of Silux and P-30 when used without previous application of a dentin adhesive. The light-cured Scotchbond proved to be as effective as GLUMA in reducing the contraction gaps of Silux providing the smear-layer was partly removed, the adhesive polymerized for 50 s and finally wetted with Silux Enamel Bond prior to application of Silux. Both adhesives had markedly less effect on the contraction gaps of the highly filled P-30.     

Depth of cure and marginal adaptation to dentin of xenon lamp polymerized resin composites.

Marginal adaptation of four resin composites (Clearfil APX, Estelite, Silux Plus and Z-100) cured with two xenon lamp units (Plasma Arc Curing System or Apollo 95E) or a halogen lamp unit (Witelite) were evaluated by measuring the wall-to-wall contraction gap width. A cylindrical dentin cavity (?3 mm x 1.5 mm) prepared in an extracted human molar was treated with the Megabond system or an experimental bonding system consisting of 0.5 M EDTA, 35% GM and Clearfil Photo Bond prior to composite filling and was irradiated for three seconds (xenon lamp) or 40 seconds (halogen lamp). The contraction gap was measured with a light microscope. In addition, the curing capability of these three light sources was evaluated by measuring the curing depth of the composites filled in a split Teflon mold (?4 mm x 8 mm). There was no marginal gap formation for Clearfil APX, Estelite and Silux Plus treated with the experimental bonding system regardless of the type of light sources. The curing depth of the xenon lamp was significantly higher than the halogen lamp, while marginal adaptation did not suffer any significant deterioration.     

Marginal adaptation of commercial compomers in dentin cavity

The dentin cavity adaptation and setting characteristics of four commercial compomers were evaluated by measuring the wall-to-wall contraction gap width in the cylindrical dentin cavity and measuring the compressive strength for a maximum of 14 days after setting. The dentin cavity wall was pretreated by the dentin adhesives according to each manufacturer's instructions or the experimental contraction gap-free dentin bonding system. Complete marginal integrity was obtained in only one compomer and two resin composites which were combined with the experimental dentin bonding system. The compressive strength of two resin composites and two compomers ten minutes after setting was comparable to that after 14 days which indicated that the compomers exhibited setting characteristics as rapidly as the resin composite. It was concluded that a high efficacy dentin bonding system is required for commercial compomers to prevent gap formation during irradiation caused by the rapid setting shrinkage.     

Marginal adaptation of dentin bonded ceramic inlays: effects of bonding systems and luting resin composites

This in vitro study evaluated the marginal adaptation of bonded inlays of lucite-reinforced glass ceramic (Empress) to dentin as influenced by different bonding systems and by luting resin composites (LRCs) with different curing modes. Forty-eight Empress inlays etched with 5% hydrofluoric acid and treated with a silane-coupling agent (Monobond-S) were bonded to two-surface Class II cavities. Two total-etch bonding systems (OptiBond FL, Nexus) and one bonding system with selective enamel etching and a self-conditioning dentin primer (ART Bond) were included in the study. ART Bond was tested with and without the pre-curing of a first layer of adhesive resin selectively applied to the cervical cavity floor (selective double-bond technique). Each bonding system was used in combination with a light-cured resin composite (Prodigy) and a dual-cured LRC (Nexus or Vita Cerec Duo Cement). Marginal integrity was evaluated before and after thermocycling (TC) in a scanning electron microscope (SEM). Dye penetration tests were performed after TC was completed. The median percentages of continuous margin in dentin ranged from 80% to 100% before TC and from 53.5% to 96.1 % after TC. After TC, the influence of the bonding system was more pronounced than that of the LRC. In combination with the LC resin composite, ART Bond with precuring was significantly higher and the Nexus bonding system had significantly lower proportions of continuous margin than all the other bonding systems investigated. Swelling of the adhesive along the gingival margins was frequently found with the Nexus bonding system and with ART Bond without pre-curing. Microleakage was detected with all bonding system/LRC combinations, with somewhat lower rates in specimens completed using the selective double-bond technique. With the exception of the Nexus bonding system, post-TC marginal integrity was not influenced by the curing mode of the LRC (LC vs DC). In conclusion, the marginal quality of dentin bonded ceramic inlays can be improved by proper selection of the bonding sys- tem/LRC combination. The results of this study indicate the use of the Nexus luting system as directed without substitution.     

Adaptation of composites to the dentin cavity wall

The cavity adaptation of marketed composite resins was evaluated by measuring the contraction gap width in a cylindrical dentin cavity. Cavity walls were cleaned with neutralized 0.5 M EDTA and treated with an aqueous solution of 35% HEMA and a dentin bonding agent. The inorganic filler content was measured by weighing specimens before and after burning. When the composite which contained an inorganic component of less than 75 wt% was employed, a relatively low contraction value of less than 0.09% was obtained. On the other hand, for the composite with an inorganic component of more than 75 wt%, the gap values varied from 0.01 to 0.43%. However, using regression analysis, no statistically significant correlation was observed between the wall-to-wall polymerization contraction and the inorganic filler content.     

Effect of cavity depth and application technique on marginal adaptation of resins in dentin cavities

The wall-to-wall polymerization contraction of two restorative resins was investigated in butt-joint dentin cavities prepared in extracted human teeth. The cavity diameter was 4 mm, and the cavity depth ranged between 0.5 and 3.0 mm. The width of the maximum marginal contraction gap was measured, using a light microscope, approximately 0.1 mm below the original free surfaces of the fillings. It was found that increasing the cavity depth from 0.5 to 3.0 mm did not influence the marginal contraction gap close to the free surfaces of the fillings. It was also found that a two-phase application technique, where the surface of the first layer was placed parallel to the free surface of the cavity, did not reduce the marginal contraction gap, while a two-phase technique with oblique layers resulted in approximately a 25% reduction.     

Effect of water sorption and thermal stress on cavity adaptation of dental composites

The effect of water sorption of composite and thermal stress on the marginal adaptation to the dentin cavity wall was evaluated by measurement of the gap width between composite fillings and the dentin cavity wall. The wall of a cylindrical dentin cavity prepared in the proximal surface of extracted human molars was cleaned with neutralized 0.5 M EDTA and pre-treated with one of three experimental dentin primers [35% hydroxyethyl methacrylate (HEMA), 35% HEMA containing 5% glutaraldehyde, and 35% glyceryl methacrylate]. A light-activated composite (Silux, 3M Co., St. Paul, MN) was used to fill the cavity after application of a bonding agent (Clearfil New Bond, Kuraray Co., Osaka, Japan). The marginal gap width was measured after the specimens were immersed in water and thermal-cycled. The initial contraction gap of the tested bonding systems was closed completely by the water sorption of the composite for six hours, and such a marginal adaptation was not interrupted by 60 thermal cycles between 10 and 45 degrees C. Among the dentin primers tested, only the 35% aqueous solution of glyceryl methacrylate mediated gap-free fillings in all specimens.     

Effect of mechanical properties of resin composites on the efficacy of the dentin bonding system

This study determined the relationship between marginal adaptation to dentin cavity preparations, tensile bond strength of the restorations, and mechanical properties of the composites. Contraction gaps, tensile bond strengths, flexural strengths, and Young's modulus of eight commercial resin composites were determined. Eight resin composites (Clearfil AP-X, Estelite, Estio LC, Litefil II-A, Prodigy, Progress, Silux Plus, and Z-100) were applied to dentin cavities or flat dentin surfaces mediated with an experimental dentin bonding system consisting of 0.5 M EDTA dentin conditioner, priming with 35% glyceryl mono-methacrylate solution, and a commercial dentin bonding agent application (Clearfil Photo Bond). The contraction gap of the resin composite in a cylindrical dentin cavity was prevented completely for three of the resin composites tested (Clearfil AP-X, Estelite, and Silux Plus). The measured tensile bond strength correlated significantly not only with the tensile strength (r2 = 0.506; 0.01 < P < 0.05), but also with the flexural strength (r2 = 0.871; P < 0.001) and Young's modulus (r2 = 0.712; 0.001 < P < 0.01) of the composites, whereas the contraction gap did not correlate significantly with the measured tensile bond strength, the tensile strength, the flexural strength, or Young's modulus (P > 0.05). However, the results did indicate that the higher tensile bond strengths measured in the traditional test may be related to the higher mechanical properties of the resin composites because of the number of specimens that exhibited cohesive failure.     

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Effect of adhesion to cavity walls on the mechanical properties of resin composites.

OBJECTIVES: To evaluate the regional mechanical properties of resin composite under free and constrained conditions during polymerization. METHODS: Forty cavities (8mm diameter and 5mm depth) were fabricated in resin blocks. Half of the cavities were bonded and the other half left un-bonded. The cavities were bulk-filled with one of the following composites: flowable composite (Palfique Estelite LV, Unifil Lo Flo), and Universal composites (Clearfil AP-X, Palfique Estelite Sigma), followed by photo-curing for 30s. After 24h storage, each specimen was sliced parallel to the long axis to harvest three slabs. The middle slab was serially sliced to harvest five sticks, which were trimmed to an hour-glass shape for measurement of regional ultimate tensile strength (UTS). The remaining semi-circular slabs were polished for microhardness measurement (KHN). Data were analyzed using three-way ANOVA followed by Tukey's HSD test and t-test (alpha=.05). RESULTS: The KHNs of all the resin composites were not significantly different between the bonded and unbonded groups at each cavity depth (p>0.05). The Ucapital TE, CyrillicS of the bonded group of flowable composites was significantly lower than those of the un-bonded group at the upper regions (p<0.05), while for universal composites, there were no significant differences in UTS between the bonded and un-bonded groups (p>0.05), although Clearfil AP-X had a trend toward lower UTS under the constrained condition at the upper regions. SIGNIFICANCE: The UTS of resin composite decreases due to polymerization shrinkage stress when polymerized under a constrained condition, however, these effects were dependent upon regions in the cavity and the resin materials.     

The effect of elevated temperatures on the dentin adhesion of resin composites

Although resin composite restorations may undergo relatively extreme temperature changes in the oral cavity, little is known about the effects of temperature on their adhesion to tooth structure. This study evaluated the effect of temperature on shear bond strength to dentin of three commercial resin dentin adhesives through testing of matured specimens over the 20 degrees to 55 degrees C temperature range. A significant difference (p < 0.05) was observed between 20 degrees C and 55 degrees C for all the materials, and for one of the materials, a significant difference was also observed between 20 degrees C and 37 degrees C.