Biomedical subjects

Marcelo Giannini

Publications and source records attributed to Marcelo Giannini.

35 records · Page 2Linked to original sources

PubMed2004

Influence of activation mode of dual-cured resin composite cores and low-viscosity composite liners on bond strength to dentin treated with self-etching adhesives.

PURPOSE: The objective of this study was to investigate the effect of light- or chemical initiation on the polymerization reaction of dual-cured composite core buildup materials (CM) with respect to their shear bond strength to dentin treated with self-etching adhesives (SE), in the presence or absence of a low-viscosity composite liner (LI). MATERIALS AND METHODS: Two SEs (Clearfil SE Bond and Unifil Core Bond), their respective CMs (DC Core Paste and Unifil Core), and a LI (Protect Liner F) were tested. After removing the labial enamel surfaces of 8 bovine incisors, each flat dentin surface was sectioned into 4 pieces with similar surface areas (30 mm2). The dentin surfaces were wet abraded with 600-grit SiC paper and randomly divided into 8 groups. Experimental groups comprised the use of a SE and its respective CM with or without an intermediate application of the LI and with or without CM light activation. Three cylinders of CM (0.5 mm high and 0.75 mm in diameter) were applied to each bonded dentin surface (n = 12), using a tygon tubing mold. After water storage for 24 h, specimens were subjected to microshear testing. Data were statistically analyzed by two-way ANOVA and Tukey's test (5%). RESULTS: For both SEs, LI application and CM light activation showed significantly higher bond strengths than the groups in which an intermediate LI was not used or the CMs were only chemically cured. CONCLUSION: The bond strength of CM to dentin using SE is reduced if the LI and light activation are not employed.

Acrylic Resins↗

PubMed2003

Effects of various finishing systems on the surface roughness and staining susceptibility of packable composite resins.

OBJECTIVES: The purpose of the present study was to investigate the influence of various finishing systems on the surface roughness and staining of three packable resin composites and a conventional microhybrid one. METHODS: Three packable composites (Solitaire-Heraeus-Kulzer, ALERT-Jeneric-Pentron, SureFil-Dentsply) and a conventional microhybrid (Z250-3M-ESPE) were used. Composite specimens were prepared and polished with Poli I and Poli II aluminum oxide pastes, Ultralap diamond paste, Enhance finishing points, Politip rubber polishers, fine and extra fine diamond burs, and 30-blade tungsten carbide burs according to the manufacturers' instructions. The polished surfaces were evaluated with a profilometer, and then immersed in 2% methylene blue for 24h. Afterwards, the specimens were prepared for the spectrophotometric analysis. Results were statistically analyzed by ANOVA and Tukey test. RESULTS: Significant differences were found for the surface roughness and staining recorded, with interaction among composite resins and the finishing systems used. No correlation was found between surface roughness and staining susceptibility (p=0.5657). SIGNIFICANCE: For most of the polishing agents used, Z250 presented the smoothest surfaces and the least dye uptake. ALERT presented the roughest surfaces, and Solitaire, the highest dye concentration. The smoothest surfaces were not necessarily the most stain resistant. Staining is highly influenced by each composite monomer and filler composition.

Analysis of Variance↗

PubMed2003

The effects of filling techniques and a low-viscosity composite liner on bond strength to class II cavities.

OBJECTIVE: The aim of this study was to test the hypothesis that the effects of filling technique, cavity configuration and use of a low-viscosity composite liner influence resin bond strength to the dentin of class II cavities gingival floor; and analyze the failure modes of fractured specimens. METHODS: Standardized class II cavities were prepared in the proximal surfaces of freshly extracted third molars, which were randomly assigned to 10 experimental groups. All prepared surfaces were acid-etched, bonded with Single Bond adhesive system and restored with TPH composite, according to each technique: G1 and G2-horizontal layering, G3 and G4-faciolingual layering, G5 and G6-oblique layering, G7 and G8-bulk filling, G9 and G10-control (flat dentin surfaces). Groups were tested, with or without a low-viscosity composite liner (Tetric Flow Chroma). After storage in water for 24h, teeth were vertically serially sectioned to yield a series of 0.8mm thick slabs. Each slab was trimmed into an hourglass shape of approximately 0.8mm(2) area at the gingival resin-dentin interface. Specimens were tested in tension at 0.5mm/min until failure. Fractured specimens were analyzed in an SEM to determine the failure modes. RESULTS: No significant difference was found between groups restored with and without a low-viscosity composite liner (p>0.05). Among filling techniques, the bulk filling groups presented the lowest bond strength values (p<0.05), while incremental filling groups did not differ from control (flat dentin surfaces). Failure modes varied significantly among groups restored with and without the low-viscosity composite liner. SIGNIFICANCE: Bond strengths were not improved when a low-viscosity composite liner was applied, but it remarkably influenced the failure modes. Incremental techniques improved bond strength.

Acid Etching, Dental↗

PubMed2003

Occluding effect of dentifrices on dentinal tubules.

OBJECTIVES: The objective of this study was to evaluate the tubule occluding ability of three commercial available dentifrices (Sensodyne, Emoform and Sorriso) by Scanning Electron Microscopy. METHODS: Fifty cervical areas from buccal and lingual surfaces of sound third human molars were used. Cervical enamel was wet abraded to expose flat dentin surfaces and further polished with diamond pastes. Specimens were randomly divided into five groups (n=10): G1-no brushing; G2-brushing without dentifrice; G3-brushing with Sensodyne; G4-brushing with Emoform; G5-brushing with Sorriso. Brushed specimens were treated for 4 min per day, for 7 days in a toothbrushing machine. Specimens were prepared and observed under SEM for calculation of the percentage of occluded tubules. In addition, slurries of toothpastes were analyzed by X-ray microanalysis. Data were statistically analyzed by ANOVA and Tukey test (p<0.05). RESULTS: Means of occluded tubules in descending order were: G5-98.83+/-3.31% (a), G4-96.02+/-5.24% (a), G3-80.12+/-24.65% (a), G1-37.31+/-24.22% (b); G2-22.92+/-15.19% (b). The three tested dentifrices produced increased dentinal occlusion as compared to controls (p<0.05) but equivalent occlusion among each other. Calcium from calcium-carbonate abrasive was identified in all dentifrices. CONCLUSIONS: Results indicated that the use of all dentifrices occluded tubules more than no brushing and brushing without dentifrices groups. Thus, the tested dentifrices seem effective for desensitization by tubule occlusion.

Analysis of Variance↗

PubMed2003

Six-month storage-time evaluation of one-bottle adhesive systems to dentin.

PURPOSE: The goal of this study was to evaluate the 1-week, 3-month, and 6-month performance of eight commercially available one-bottle adhesive systems to dentin. MATERIALS AND METHODS: Lingual and buccal surfaces from human third molars were ground wet on 600-grit SiC paper to obtain a flat dentinal surface. The specimens were randomly divided into 24 groups (n = 10), which were established to measure the shear bond strengths of Bond-1 (B1), ONE-STEP (OS), OptiBond SOLO (OP), Prime & Bond 2.1 (PB), Single Bond (SB), STAE (ST), Syntac Sprint (SS), and Tenure Quick (TQ) after 1-week, 3-month, and 6-month water storage at 37 degrees C. One-bottle adhesives were applied according to manufacturers' instructions and Z100 composite cylinders were applied on the bonded dentinal surfaces. The 3-month water-storage groups were thermocycled for 1500 cycles at 5 degrees C and 55 degrees C and 6-month groups for 3000 cycles. After storage periods, specimens were tested in shear in a universal testing machine (0.5 mm/min). RESULTS: were statistically analyzed by analysis of variance and Tukey test. Results: The changes in shear bond strengths were not uniform over time. Over the test period, OS, PB, SB, and SS exhibited bond strength stability, however, SS presented low bond strengths on all tested periods. A significant decrease in bond strength was observed for B1, OP, ST, and TQ after the 6-month storage period.

Analysis of Variance↗

PubMed2002

Esthetic rehabilitation of anterior teeth affected by enamel hypoplasia: a case report.

UNLABELLED: Alterations during tooth structure formation, mainly on anterior teeth, are known to severely compromise esthetics. This article presents a case report in which the etiology and clinical characteristics of anterior teeth affected by enamel hypoplasia are analyzed. The restoration treatment sequence is also discussed, demonstrating that the use of a hybrid and a microfilled composite associated with tooth hybridization (interdiffusing zone) can be used to conservatively rehabilitate a smile. CLINICAL SIGNIFICANCE: This article presents a simple and conservative technique for restoring disfiguring areas of enamel hypoplasia to achieve an optimally esthetic result.

Acid Etching, Dental↗

PubMed2002

Effect of surface roughness on amalgam repair using adhesive systems.

The objective of this in vitro study was to evaluate the effect of three surface treatments and two adhesive systems on the shear bond strength of old and freshly placed amalgam. The results suggested that the intact amalgam showed a significantly higher strength than repaired groups and the strongest repaired specimens were made when the amalgam surfaces were roughened with a diamond bur or microetcher. The adhesive systems showed no significant differences on bond strength with the same superficial texture.

Analysis of Variance↗

PubMed2002

The effect of six polishing systems on the surface roughness of two packable resin-based composites.

PURPOSE: To evaluate the surface roughness of two packable composites after finishing and polishing with six different systems. MATERIALS AND METHODS: Solitaire and Alert composite samples were prepared and polished with Poli I and Poli II aluminum oxide pastes, Ultralap diamond paste, Enhance finishing points, Politip rubber polishers, fine and extra fine diamond burs, and 30-blade tungsten carbide burs according to the manufacturers' instructions. The polished surfaces were then evaluated with a profilometer and a scanning electron microscope. RESULTS: Solitaire composite resin presented the smoothest surfaces when polished with Poli I and II aluminum oxide pastes, Ultralap diamond paste, Politip finishing points and 30-blade tungsten carbide burs. The smoothest surfaces for Alert composite were evident with the 30-blade tungsten carbide burs.

Aluminum Oxide↗

PubMed2002

Influence of smear layer pretreatments on bond strength to dentin.

PURPOSE: To evaluate the tensile bond strength of two self-etching adhesive systems and one one-bottle system applied on dentin surfaces after different smear layer treatments. MATERIALS AND METHODS: The crowns of 36 extracted third molars were transversally sectioned with a diamond saw to expose dentin. Flat dentin surfaces were abraded wet with 600-grit SiC paper and randomly assigned to 12 groups, according to three adhesive systems--Prime & Bond NT (PB), Clearfil Mega Bond (CMB) and Etch & Prime 3.0 (EP)--and four dentin surface treatments: direct application over smear layer (no treatment), sandblasting with 50 microm Al2O3 for 10 s, etching with 36% phosphoric acid for 15 s, or conditioning with 0.5 M EDTA for 2 min. Composite "crowns" (6.0 mm high) were incrementally built on the bonded surfaces and teeth were stored in distilled water at 37 degrees C. Teeth were vertically, serially sectioned in both x and y directions to obtain bonded specimens of approximately 0.8 mm2 cross-sectional area. Each specimen was tested in tension in a universal testing machine at 0.5 mm/min. RESULTS: Overall microtensile bond strength (MPa) was 40.43 +/- 7.63 for PB, 27.03 +/- 8.40 for CMB, and 14.73 +/- 3.91 for EP. Mean bond strength for PB was significantly higher than self-etching systems. No significant differences were observed among smear layer treatments within the same dentin adhesive. CONCLUSION: Bond strength values were significantly different according to the adhesive system used. Different smear layer treatments prior to bonding did not affect tensile bond strength within the same bonding agent.

Acid Etching, Dental↗

PubMedDate not supplied

Morphology and thickness of the diffusion of resin through demineralized or unconditioned dentinal matrix.

The formation of a hybrid layer is the main bonding mechanism of current dentin-bonding systems. This study evaluated the morphology and thickness of the resin-infiltrated dentinal layer after the application of adhesive systems. The dentin-bonding agents were evaluated on flat dentinal preparations confected on the occlusal surfaces of human teeth. The test specimens were prepared and inspected under scanning electron microscopy at a magnification of X 2,000. The adhesive systems were responsible for different hybrid layer thicknesses (p < 0.05), and the mean values were: for Scotchbond MP Plus (SM), 7.41 +/- 1.24 micrometer for Single Bond (SB), 5.55 +/- 0.82 micrometer for Etch & Prime 3.0 (EP), 3.86 +/- 1.17 micrometer and for Clearfil SE Bond (CB), 1.22 +/- 0.45 micrometer. The results suggest that the conventional three-step adhesive system (SM) was responsible for the thickest hybrid layer, followed by the one-bottle adhesive (SB). The self-etching adhesives, EP and CB, produced the formation of the thinnest hybrid layers.

Acrylic Resins↗

PubMedDate not supplied

Effect of irradiation mode and filling technique on resin/dentin bonding strength in Class I cavities.

Factors such as light-curing mode, filling technique and cavity configuration may affect the bonding strength to dentin. This study evaluated the effect of irradiation mode and filling technique on resin/dentin bonding strength on the buccal wall of Class I cavities in human teeth. Occlusal enamel was removed to expose a flat dentin surface. Occlusal cavities (4 x 3 x 3 mm) were prepared in dentin. The adhesive Single Bond was applied according to the manufacturer's instructions and TPH Spectrum composite resin was placed using the following: oblique incremental, horizontal incremental or bulk filling techniques. The composite resin was light-cured either by continuous (600 mW/cm2 for 40 s) or Soft-Start (250 mW/cm2 for 10 s + 600 mW/cm2 for 30 s) modes. Specimens of the control group were obtained by bonding the material to the flat exposed buccal wall of the cavity (C-factor = 1). The teeth were stored in water at 37 degrees C for 24 h and prepared for microtensile testing. Bonded beams of approximately 0.8 mm2 were obtained from the buccal wall and tested with a tension of 0.5 mm/min. Results were analyzed by two-way ANOVA, Tukey's test and Dunnett's test (alpha = 0.05). Incremental placement techniques with both irradiation modes produced higher bonding strength values than the bulk technique (p < 0.05). Bonding strength tested in the cavities had lower values than those obtained in flat dentin surfaces (control group) (p < 0.05), except for incremental fillings using stepped irradiation. Bonding strength to the cavity walls depends on the filling technique and on the irradiation mode of composite resins.

Analysis of Variance↗

PubMedDate not supplied

Peroxide bleaching agent effects on enamel surface microhardness, roughness and morphology.

The aim of this study was to evaluate the surface roughness, microhardness and morphology of human enamel exposed to six bleaching agents (at baseline and post-treatment). Human dental enamel samples were obtained from human third molars and randomly divided into seven groups (n = 11): control, Whiteness Perfect--10% carbamide peroxide (10% CP), Colgate Platinum--10% CP, Day White 2Z--7.5% hydrogen peroxide (7.5% HP), Whiteness Super--3% CP, Opalescence Quick--35% CP and Whiteness HP--35% HP. Bleaching agents were applied according to manufacturers' instructions. The control group remained not treated and stored in artificial saliva. Microhardness testing was performed with a Knoop indentor and surface roughness was analyzed with a profilometer. Morphologic observations were carried out with scanning electron microscopy (SEM). Results were statistically analyzed by two-way analysis of variance and Tukey's test (5%), and revealed a significant decrease in microhardness values and a significant increase in surface roughness post-bleaching. Changes in enamel morphology after bleaching were observed under SEM. It was concluded that bleaching agents can alter the microhardness, roughness and morphology of dental enamel surface.

Carbamide Peroxide↗

PubMedDate not supplied

Influence of carbamide peroxide-based bleaching agents on the bond strength of resin-enamel/dentin interfaces.

In this bond strength study, a bleaching agent containing 10% carbamide peroxide was applied over composite-teeth bonded interfaces of two adhesive systems applied to enamel and dentin. Sixteen human third molars were used for bonding procedures. Single Bond (SB) and Clearfil SE Bond (CB) were applied to enamel and dentin according to the manufacturers' instructions. A resin composite cube-like structure was incrementally built on the bonded surfaces. The restored teeth were sectioned into 0.7 mm thick slices that were trimmed at enamel or dentin bonded interfaces to an hourglass shape with a cross-sectional area of approximately 0.5 mm2. Specimens were assigned to 8 groups (n = 10) according to the following factors under study: dental substrate (enamel and dentin); adhesive system (SB and CB) and treatment (10% carbamide peroxide and not bleached/control). The bleaching gel (Opalescence) was applied at the bonded interfaces for 6 hours during 14 days and after daily treatment specimens were stored in artificial saliva. Unbleached specimens were stored in artificial saliva for 14 days. Specimens were tested for tension and the data were analyzed by three-way ANOVA and Tukey's test (p < 0.05). Enamel tensile bond strength of CB was reduced after carbamide peroxide application. The bleaching treatment did not alter dentin bond strength of both adhesives. The results suggest that bleaching significantly affects bond strength of CB to enamel, but no influence on bond strength to dentin was noted for both adhesive systems.

Analysis of Variance↗

PubMedDate not supplied

Marginal adaptation of indirect composites and ceramic inlay systems.

This study evaluated the marginal adaptation of four different inlay indirect restorative systems: feldspathic ceramic (Duceram LFC-Degussa) and three laboratory-processed resin composites (Solidex-Shofu; Targis-Ivoclar; Artglass-Heraeus Kulzer). Sixty mesial-occlusal-distal (MOD) standard cavities were prepared in mandibular molars and divided randomly. Polyvinylsiloxane impressions were made and the restorations were prepared following the manufacturer's instructions. Marginal adaptation evaluation was accomplished using an image collector computer system with a digital gauging appliance at four points on the occlusal, proximal and gingival regions with 250x magnification. Among all the materials, the marginal discrepancy recorded on the gingival margins was statistically larger than that recorded on the proximal and occlusal regions. Duceram LFC showed greater marginal discrepancy than Solidex, Artglass and Targis, which showed no statistically significant differences among them.

Aluminum Silicates↗

PubMedDate not supplied

The effect of organic solvents on one-bottle adhesives' bond strength to enamel and dentin.

This study evaluated the microtensile bond strength (pTBS) of ethanol/water- and acetone-based, one-bottle adhesive systems to enamel (E) and dentin (D) in the presence (P) or absence (A) of their respective solvents. Thirty-two freshly extracted third molars were flattened with 600-grit SiC paper and restored with Single Bond (SB) or Prime&Bond 2.1 (PB) according to the manufacturers' instructions and after full solvent elimination. The molars were divided into eight test groups (n = 4): G1-SB-E-P, G2-SB-E-A, G3-PBE-P, G4-PB-E-A, G5-SB-D-P, G6-SB-D-A, G7-PB-D-P and G8-PB-D-A. After applying the adhesive resins, composite crowns of approximately 8 mm were built up with TPH Spectrum composite. After 24-hour water storage, the specimens were serially sectioned bucco-lingually to obtain 0.8 mm slabs that were trimmed to an hourglass shape, approximately 0.8 mm2 at the bonded interface. The specimens were tested in tension using a universal testing machine (0.5 mm/minute). The results were statistically analyzed by ANOVA and Tukey test. The frequency of fracture mode was compared using the Kruskal-Wallis test. There were no statistically significant differences in mean bond strength among the groups restored with or without solvent for enamel. However, the results were significantly different for the dentin groups (MPa): G5-26.2 +/- 8.6a; G7-23.6 +/- 11.3ab; G6-12.8 +/- 2.1bc; G8-6.2 +/- 3.1c. SEM examination indicated that the dentin group failure modes were significantly different from the enamel groups. The results suggest that the presence of organic solvents does not influence microTBS to enamel. However, microTBS to dentin was significantly affected by the absence of solvents in the adhesive system.

Acetone↗

PubMedDate not supplied

Curing depth of a resin-modified glass ionomer and two resin-based luting agents.

The degree of conversion of resin-based luting agents used for retention of prefabricated posts has been questioned due to the difficulty of light penetration into the resin-filled root canal. This study evaluated the depth of cure of a resin-modified glass ionomer cement (Rely X--3M ESPE) and two resin-based luting agents (Rely X ARC--3M ESPE and Enforce-Dentsply). Twenty-four 14x2x2mm3 specimens were prepared in a Teflon split mold with the three luting agents (n=8). After preparation, the specimens were stored at 37 degrees C in a dark box for 24 hours prior to microhardness testing. Measurements of Knoop hardness were performed at three different depths: superficial, medium and deep thirds. The results (KHN) were statistically analyzed by repeated measures ANOVA and Tukey test (0.05), which showed that resin-based luting agents presented the highest Knoop hardness values within the superficial third. Within the medium third, there were no significant differences among luting materials. However, within the deep third, Rely X presented the highest values. KHN values of resin-based luting agents decreased remarkably as depth increased.

Bisphenol A-Glycidyl Methacrylate↗

PubMedDate not supplied

Effect of peroxide-based bleaching agents on enamel ultimate tensile strength.

This study evaluated the effects of peroxide bleaching regimens on the ultimate tensile strength (UTS) of human enamel. A resin composite block was built-up on the bonded occlusal surface of 14 extracted, sound, erupted third molars to enable posterior preparation for the microtensile test. The bonded teeth were serially sectioned in a buccal-lingual direction into approximately 0.7-mm thick slices. Each slice was trimmed with a fine diamond bur to reduce the area of the buccal, internal slope of the cusps to a dumb-bell shape with a cross-sectional area of less than 1 mm2. The samples were randomly divided into seven groups (n = 10): unbleached control group and bleached groups treated with six bleaching regimens. The specimens were tested in tension at 0.5 mm/minute and the data were analyzed by ANOVA and Tukey test. Specimens from the control group presented 51.3 +/- 8.6 MPa, while the UTS of bleached enamel ranged from 22.0 +/- 5.6 to 36.3 +/- 9.1 MPa. All bleaching procedures significantly reduced enamel UTS (p < 0.05). Differences were also observed among treatments. The results suggested that bleaching regimens can significantly reduce enamel UTS.

Analysis of Variance↗