The Inhibitory Effect of MI Paste, Fluoride and a Combination of Both on the Progression of Artificial Caries-like Lesions in Enamel

It is important to evaluate the inhibitory effect on lesion progression of CPP-ACP when delivered in a mousse vehicle, commercially known as MI Paste, and compare it to actual remineralization products already established.

A conservative aesthetic solution for a single anterior edentulous space: case report and one-year follow-up

Conservative solutions for the restoration of a single edentulous space in the anterior maxilla present an aesthetic challenge to the clinician. Treatment options for tooth replacement include implant placement, a classical fixed partial denture, or a resin-bonded appliance with a metal substructure or fiber-reinforced resin. The resin-bonded Encore Bridge (daVinci Studios, Woodland Hills, CA) offers a restorative solution that is conservative and aesthetic when compared to the required full-tooth preparation in a conventional three-unit fixed partial denture. This case report addresses the indications, preparation guidelines, and restorative procedures for an Encore Bridge.

Cavity preparation devices: effect on microleakage of Class V resin-based composite restorations

PURPOSE

To evaluate the effect of cavity preparation device (i.e. carbide bur, diamond bur, air abrasive, Sonicsys, and Er:YAG laser) on microleakage of Class V resin-based composite (RBC) restorations, the tooth restoration interface and dentin ultrastructure.

MATERIALS AND METHODS

Eight groups (n=18) of 9 human molars each were prepared on the buccal and lingual surfaces for Class V RBC restorations using five preparation devices: Group 1: carbide bur #8 round; Group 2: diamond bur #801; Group 3: KCP 1000 air abrasion unit; Group 4: Sonicsys Approx.; Group 5: Er:YAG laser; Group 6: carbide bur plus air abrasive; Group 7: carbide bur plus laser, and Group 8: laser without etching. Circular cavity preparations, 3 mm diameter and 1.5 mm deep, were cut at the CEJ on the buccal and lingual surfaces of each tooth. A bevel was placed on the enamel margin. All cavities were restored using Single Bond adhesive system and Silux Plus according to manufacturer's directions, with the exception that no etchant was used with Group 8. After thermocycling, specimens were tested for microleakage using silver nitrate methodology. Dye penetration data was collected and subjected to non-parametric statistical analysis. SEM analysis of the dentin-RBC interface, as well as the effect of each cavity preparation device on the surface of dentin was performed.

RESULTS

Microleakage did not occur in enamel for any method of cavity preparation when the enamel was etched prior to adhesive application. Kruskal-Wallis One-way ANOVA revealed differences in dentin microleakage among the tested groups at alpha=0.05. Mann-Whitney Test for Paired Comparisons at alpha=0.01 demonstrated significantly greater dentin microleakage in Groups 5 and 7 compared to all groups except Group 3 (air abrasive). Although Group 8 had the least microleakage in dentin, this was not significantly different from Groups 1, 2, 4 and 6. SEM observation revealed hybridization at the dentin-resin interface for all groups except for Group 8 (laser prepared, non-etched). Surface analysis showed differences related to the operating mode of each preparation device.

CLINICAL SIGNIFICANCE

The method of cavity preparation did not affect microleakage in etched enamel. When using a laser for cavity preparation, enamel should be etched although not etching dentin may help to improve marginal seal.

The physical properties of packable and conventional posterior resin-based composites: a comparison

BACKGROUND

The authors compared the physical properties of three packable hybrid resin-based composites with those of a conventional hybrid and a microfill composite material advocated for use as posterior restorative materials. They evaluated diametral tensile strength, or DTS; compressive strength, or CS; flexural strength, or FS; and depth of cure, or DC.

METHODS

The authors studied the following resin-based restorative materials: three packable composites, Alert Condensable Composite (Jeneric Pentron), SureFil High Density Posterior Restorative (Dentsply Caulk) and Solitaire (Heraeus Kulzer); one conventional hybrid composite, TPH Spectrum (Dentsply Caulk); and one microfill, Heliomolar Radiopaque (Ivoclar-Vivadent). The authors evaluated DTS, CS, FS and DC, according to American National Standards Institute criteria. They made scanning electron micrographs of the packable resin-based composites.

RESULTS

Results demonstrated that the conventional hybrid, TPH Spectrum, had significantly greater DTS and FS than other resin-based composites. Alert and SureFil had comparable DTS and FS, which were significantly greater than Heliomolar's DTS and FS. Solitaire had significantly lower DTS and FS than all other resin-based composites. SureFil had the highest CS, followed by TPH Spectrum, Solitaire and Alert, which were comparable and had significantly greater CS than Heliomolar. TPH Spectrum and Alert had significantly greater DC than all other resin-based composites, followed in decreasing order by SureFil, Solitaire and Heliomolar.

CONCLUSION

While the packable composites tested in this study had physical properties superior to those of the microfill composite, they were no better suited for use as a posterior restorative material than was the conventional hybrid resin-based composite.

CLINICAL IMPLICATIONS

Packable composites may be easier for clinicians to handle than conventional resin-based composites; however, their physical properties were not superior to those of the conventional small-particle hybrid resin-based composite. In addition, these materials may have the clinical drawback of increased wear and surface roughness that was seen with early, large-particle composite restorative materials.

A direct approach to restore anterior teeth

When selecting the correct treatment for a patient with anterior esthetic problems, the dentist must choose between direct and indirect procedures. With situations allowing conservative treatment, direct resin restoration should be given strong consideration. Advances in materials and techniques that can positively affect this choice include pre-restorative bleaching procedures, new bonding agents, and new highly esthetic direct resin systems. A procedure is described to maximize esthetics and minimize finishing time during direct resin placement.

Amalgam shear bond strength to dentin using single-bottle primer/adhesive systems

PURPOSE

To evaluate the in vitro shear bond strengths (SBS) of a spherical amalgam alloy (Tytin) to dentin using several single-bottle primer/adhesive systems both alone: Single Bond (SB), OptiBond Solo (Sol), Prime & Bond 2.1 (PB), One-Step (OS) and in combination with the manufacturer's supplemental amalgam bonding agent: Single Bond w/3M RelyX ARC (SBX) and Prime & Bond 2.1 w/Amalgam Bonding Accessory Kit (PBA). Two, three-component adhesive systems, Scotchbond Multi-Purpose (SBMP) and Scotchbond Multi-Purpose Plus w/light curing (S + V) and w/o light curing (S+) were used for comparison.

MATERIALS AND METHODS

One hundred eight extracted human third molars were mounted lengthwise in phenolic rings with acrylic resin. The proximal surfaces were ground to expose a flat dentin surface, then polished to 600 grit silicon carbide paper. The teeth were randomly assigned to 9 groups (n = 12), and dentin surfaces in each group were treated with an adhesive system according to the manufacturer's instructions, except for S + V specimens, where the adhesive was light cured for 10 s before placing the amalgam. Specimens were then secured in a split Teflon mold, having a 3 mm diameter opening and amalgam was triturated and condensed onto the treated dentin surfaces. Twenty minutes after condensation, the split mold was separated. Specimens were placed in distilled water for 24 hrs, then thermocycled (300 cycles, between 5 degrees C and 55 degrees C, with 12 s dwell time). All specimens were stored in 37 degrees C distilled water for 7 days, prior to shear strength testing using a Zwick Universal Testing Machine at a cross-head speed of 0.5 mm/min.

RESULTS

The highest to the lowest mean dentin shear bond strength values (MPa) for the adhesive systems tested were: S + V (10.3 +/- 2.3), SBX (10.2 +/- 3.5), PBA, (6.4 +/- 3.6), SOL (5.8 +/- 2.5), SBMP (5.7 +/- 1.8), S+ (4.8 +/- 2.3), PB (2.7 +/- 2.6), SB (2.7 +/- 1.1) and OS (2.5 +/- 1.8). One-way ANOVA and Duncan's Multiple Range Test indicated significant differences among groups. SBX and S + V produced significantly higher amalgam to dentin shear bond strengths than all other adhesive systems. Bond strengths of amalgam to dentin for the single-bottle adhesives, SOL and PBA were comparable to the three-component systems, SBMP and S+ and were significantly greater than OS, SB and PB (P < 0.05).

Evaluation of acidic primers in microleakage of Class 5 composite resin restorations

The purpose of this in vitro study was to evaluate the marginal seal of two adhesive systems on class 5 composite resin restorations. Two adhesive systems that use acidic primers were used in this study: Clearfil Liner Bond 2 and Denthesive II. Scotchbond Multi-Purpose was used as a control. Class 5 cavity preparations were made at the CEJ (half of the preparation was in enamel and half in dentin/cementum) of 60 extracted human molars. Both systems were used with and without etching. The control group was used with etching only. Composite resin restorations were placed, light cured for 40 seconds, and polished. All specimens were thermocycled 500 times. The specimens were immersed in erythrosin B, tetra-iodo-fluorescent 2% solution, then sectioned to obtain 600 mm-thick sections. These were examined under X13.2 magnification, and the degree of dye penetration was measured in microns. A chi-square test demonstrated no significant differences in microleakage among groups for either dentin (P = 0.54) or enamel (P = 0.35).

Protocol for predictable restoration of anterior teeth with composite resins

The composite resins have reached a high degree of excellence and are now used with predictable results in restoring the anterior dentition. This article discusses the development of these resins and the histologic and optical considerations (polychromatic characteristics, hue translucency and opacity, chroma, value, strength and polishability). In restorative materials, the use of universal or all-purpose restorative resins is considered: i.e. materials that combine the junctional strength necessary for the posterior regions and the high gloss polishability necessary to emulate enamel in the anterior. The restorative sequence of cervical, middle, and incisal thirds describes the materials best suited for each third, along with aids to create the intricate refinement of hue, chroma, and value. The learning objective of this article is to review the principles involved in these restorations and to provide a protocol for their clinical implementation.

Adhesive composite inlays for the restoration of cracked posterior teeth associated with a tongue bar

While body piercing has become fashionable in contemporary society, numerous health risks are directly related to this trend. Tongue piercing in particular presents several concomitant complications for the attending clinician, including the possibility of soft tissue infection or damage to the natural dentition or existing restorations. Clinicians must be proficient in the selection of the proper materials and techniques utilized to treat affected patients. This article details a comprehensive clinical protocol for the use of adhesive composite inlay restorations for cracked posterior teeth.

Interfacial ultrastructure of the resin-enamel region of three adhesive systems

PURPOSE

To observe the resin/enamel interface produced by different adhesive systems.

MATERIALS AND METHODS

A conventional three-step smear layer removing adhesive system (Scotchbond Multi-Purpose), a two-step smear layer removing adhesive system (Prime & Bond), and a two-step smear layer dissolving adhesive system containing a self-etching primer (Panavia 21) were evaluated. Flat enamel surfaces were obtained from approximal surfaces of 18 extracted human molars. A total of 36 surfaces were collected and divided into three groups of 12 samples. One-half of each specimen in each group was etched with 35% phosphoric acid prior to the application of each adhesive system, with the second half being kept unetched. Subsequently, resin composite was placed and polymerized for 40 seconds. The samples were fractured and immersed into HCl and NaOCl solutions, followed by critical point drying and sputter coating for examination with a field emission scanning electron microscope.

RESULTS

In the etched samples, Panavia 21 and Scotchbond Multi-Purpose showed more consistent resin tag penetration than did Prime & Bond. Unetched Prime & Bond and Scotchbond Multi-Purpose samples showed minimal or no adhesive penetration in enamel surfaces.

An in vitro comparison of three fluoride regimens on enamel remineralization

The purpose of this study was to compare the enamel remineralization effectiveness of a fluoride rinse, fluoridated dentifrice, and fluoride-releasing restorative material. Forty extracted molars had 1 x 5 mm artificial carious lesions formed at the interproximal contact point. One-hundred-micrometer sections were obtained at the caries sites, and polarized light photomicrographs were obtained. The sections had varnish placed, leaving only the external section site exposed, and were situated back into the original tooth. Forty other molars were obtained; 10 had Class-II glass ionomer cement restorations placed. These 40 teeth were mounted to have interproximal contact with the adjacent teeth containing artificial carious lesions. Specimens were placed in closed environments of artificial saliva for 1 month, with saliva being changed every 48 h. Ten specimen pairs were brushed with a fluoridated dentifrice for 2 min, twice per day, 10 specimen pairs were rinsed with a 0.05% sodium fluoride rinse for 1 min twice per day, 10 specimen pairs had Class-II glass ionomer cement restorations positioned adjacent to 10 teeth with artificial carious lesions, and 10 specimen pairs acted as controls. After 30 days, the same sections were photographed again under polarized light, and areas of the lesions were digitized quantitatively. Results demonstrated the mean (+/- SD) remineralization (mu m2) in Thoulet's 1.41 imbibition media to be: lesions adjacent to glass ionomer cement restorations, 2.45 +/- 170; lesions exposed to a fluoridated dentifrice, 223 +/- 102; lesions exposed to 0.05% sodium fluoride rinse, 374 +/- 120, and control lesions only exposed to artificial saliva, 101 +/- 69. Duncan's analysis indicated the fluoridated rinse to have significantly greater remineralization effects on adjacent caries than the other groups (p < or = 0.05). The glass ionomer restorative material and fluoridated dentifrice also had significantly greater remineralization effects on adjacent caries than the control, yet significantly less than the fluoridated rinse (p < or = 0.05).

Evaluation of adhesive systems using acidic primers

PURPOSE

To evaluate in vitro the dentin and enamel shear bond strength of two adhesive systems that contain acidic primers.

MATERIALS AND METHODS

Clearfil Liner Bond 2 (CLB2) and Denthesive II (DTII), containing acid primers were used with (ETCH) and without (NOET) etching. Scotchbond Multi-Purpose (SBMP) was utilized as a control. Sixty flat enamel and dentin bonding sites were prepared to 600 grit on extracted human molars. Both acidic primer systems were used with (ETCH) and without etching (NOET) for both enamel and dentin surfaces. The control group used etching only. After applying primer and adhesive, a microfill composite (Silux Plus) was placed in a 2.5 mm diameter matrix on the tooth surface, and polymerized for 40 seconds. All specimens were thermocycled 500 times. Shear bond strengths were determined using a Zwick testing machine.

RESULTS

One-way ANOVA revealed significant differences among groups for enamel (P = 0.0001) and dentin (P = 0.0002). Duncan's multiple range test (alpha = 0.05) revealed that enamel shear bond strength of DTII-ETCH was equal to that of CLB2-NOET and these were significantly greater than CLB2-ETCH, SBMP and DTII-NOET. For dentin, bond strengths for CLB2-ETCH and CLB2-NOET were significantly greater than DTII-NOET.

Interfacial micromorphology and shear bond strength of single-bottle primer/adhesives

OBJECTIVES

This study was conducted 1) to characterize through SEM analysis the resin-dentin interface produced by single-bottle primer/adhesives and a three-component system [Scotchbond Multi-Purpose (3M Dental)] and 2) to evaluate the shear bond strength to dentin of these adhesive systems.

METHODS

Single-bottle primer/adhesives [Bond 1 (Jeneric/Pentron), Single Bond, (3M Dental Products); One Step (Bisco Inc.), OptiBond Solo (Kerr Corp.), Prime & Bond 2.1 (L.D. Caulk-Dentsply), Syntac Single-Component (Ivoclar-Vivadent), Tenure Quilk with Fluoride (Den-Mat)] were used according to manufacturers' instructions to bond resin composite to flat dentinal surfaces of extracted human third molars (n = 15). All samples were thermocycled 300x. Twelve specimens per group were used to measure shear bond strength and three specimens were used to evaluate the interfacial morphology under SEM. A one-way ANOVA and Turkey's test were used to assess the results.

RESULTS

Mean shear bond strengths in MPa +/- SD for the groups ranged from 22.27 +/- 4.5 MPa for Single Bond to 7.6 +/- 3.9 MPa for Syntac Single-Component. The statistical analysis indicated that Single Bond produced significantly higher (p < 0.001) bond strengths than Syntac Single-Component, Prime & Bond 2.1, Bond 1 and Tenure Quik With Fluoride. Bond strengths for Syntac Single-Component were significantly lower than One-Step, OptiBond Solo, Scotchbond Multi-Purpose Plus and Single Bond. SEM examination clearly revealed the formation of a distinct hybrid layer for all adhesive systems; however, minor variations in ultrastructure existed among products.

SIGNIFICANCE

Some single-bottle primer/adhesive present in vitro bond strengths and hybrid layer formation similar to those found for the conventional three-component adhesive system tested.

Dentin desensitizing agents: SEM and X-ray microanalysis assessment

PURPOSE

To evaluate the effect of four proprietary dentin desensitizing agents on dentin tubular occlusion, chemical composition changes on the dentin surface, and the effect of saliva and toothbrushing on these agents.

MATERIALS AND METHODS

Fifty dentin discs, obtained from 50 freshly extracted human premolar and molar teeth were used in this study. These were divided into five groups of 10 discs each. Five discs from each group were treated with the desensitizing agents, viewed under the SEM and subjected to energy dispersive X-ray analysis. The other five discs were treated with the desensitizing agents, immersed in artificial saliva, subjected to simulated toothbrushing equivalent to 3 weeks of normal brushing and viewed under the SEM. The agents studied were Sensodyne Dentin Desensitizer, Therma-Trol Desensitizer Gel, Gluma Desensitizer and All-Bond DS.

RESULTS

The Kruskal-Wallis test followed by the Wilcoxon signed-rank test showed that Sensodyne Dentin Desensitizer exhibited the greatest amount of tubular occlusion among the unbrushed samples, followed by Therma-Trol Desensitizer Gel, Gluma Desensitizer and All-Bond DS (P < 0.05) in that order. Toothbrushing increased tubular occlusion in all cases except the Sensodyne Dentin Desensitizer treated samples.

Effect of condensation techniques on amalgam bond strengths to dentin

This in vitro study determined the shear bond strengths of Tytin amalgam to dentin using All-Bond 2, Amalgambond Plus, Amalgambond Plus with HPA powder, and OptiBond with hand and mechanical (Condensaire) condensation. The occlusal enamel surfaces were ground flat to expose the dentin surfaces, and polished with 600-grit SiC paper. The dentin surfaces were treated with one of the combinations of a dentin bonding agent and a condensation technique. All specimens were thermocycled 300 cycles in water between 5-55 degrees C, and shear bond strengths were determined with a Zwick Universal Testing Machine. Two-way ANOVA and Duncan's tests showed no significant differences (P > 0.05) in shear bond strength between hand and mechanical condensation of the paired groups, with the exception of Amalgambond Plus, where hand condensation was shown to be significantly better. For both condensation techniques, shear bond strength of Amalgambond Plus with HPA powder was significantly higher than the other materials. For mechanical condensation, OptiBond was significantly higher than either Amalgambond Plus or All-Bond 2, and no significant difference was found between Amalgambond Plus and All-Bond 2. For hand condensation, OptiBond was only significantly higher than All-Bond 2, while there was no significant difference between OptiBond and Amalgambond Plus or between Amalgambond Plus and All-Bond 2. In conclusion, for both condensation techniques, Amalgambond Plus with HPA powder performed the best in bonding amalgam to dentin. The two different condensation techniques did not significantly affect shear bond strength, except with Amalgambond Plus.

Effect of desiccation on microleakage of five Class 5 restorative materials

Resin-modified glass ionomers, combinations of resin and glass-ionomer chemistry, have resulted in materials with longer working times and command set by visible light activation. These materials are easier to use and more resistant to early moisture contamination and fracture. A glass-ionomer or resin-modified glass-ionomer restoration may be inadvertently desiccated by isolation of the same quadrant for subsequent restorative procedures. The present study is an assessment of the effects of desiccation on microleakage of three resin-modified glass-ionomers: Vitremer, Photac-Fil, Fuji II LC; a glass-ionomer, Ketac-Fil; and a microfill resin, Silux Plus. Fifty extracted molars were prepared with class 5 preparations buccal and lingual and randomly assigned to 10 groups (n = 10). Restorations were placed according to the manufacturers' specifications and finished wet after the manufacturers' specified setting interval. All samples were thermocycled 300 cycles between 50 and 500 degrees C. Samples were stored in water at all times until the five groups to be desiccated were air dried and stored dry for 45 minutes. Desiccated groups were then rehydrated for 24 hours prior to AgNO3 staining. Teeth were sectioned mesiodistally and four buccolingual sections (0.6 mm thick) through each class 5 restoration were obtained with a Silverstone-Taylor hard tissue microtome. Each section was scored on a scale of 0-4 for microleakage, and the highest score for dye penetration was used as the score for that restoration. An increase in microleakage was observed in all desiccated groups. Three materials showed a statistically significant increase in microleakage (P < 0.05) following desiccation. Microleakage increases following a brief period of desiccation corresponding to typical treatment times indicate that clinicians need to protect previously placed restorations from undue drying during subsequent dental treatment.

Class V restorations utilizing a new compomer material: a case presentation

Restorative materials used in the anterior cervical region should be able to restore the affected area in an aesthetic manner, require only a minimal amount of tooth structure removal, and provide protection from further cervical decalcification. The latest generation of restorative materials have combined the qualities of composite resins and glass-ionomers. Some of these materials incorporate resin components into glass-ionomer systems and are termed resin-modified glass-ionomers; others add glass-ionomer particles to acidic polymerizable monomers in a resin matrix and are commonly called "compomers." The learning objective of this case report is to present a step-by-step clinical procedure for restoration of a Class V defect in the maxillary anterior region, using a recently introduced "compomer."

Protocol for predictable restoration of anterior teeth with composite resins

The composite resins have reached a high degree of excellence and are now utilized with predictable results in restoring the anterior dentition. This article discusses the development of these resins and the histologic and optical considerations (polychromatic characteristics, hue, translucency and opacity, chroma, value, strength, and polishability). In restorative materials, the use of universal or all-purpose restorative resins is considered, ie, materials that combine the functional strength necessary for the posterior regions and the high gloss polishability necessary to emulate enamel in the anterior. The restorative sequence of cervical, middle, and incisal thirds describes the materials best suited for each third, along with aids to create the intricate refinement of hue, chroma, and value. The learning objective of this article is to review the principles involved in these restorations and to provide a protocol for their clinical implementation.

Amalgam shear bond strength to dentin using different bonding agents

This study evaluated the shear bond strength of amalgam to dentin using five different bonding agents: Amalgambond Plus, Optibond, Imperva Dual, All-Bond 2, and Clearfil Liner Bond. Flat dentin surfaces obtained by grinding the occlusal portion of 50 human third molars were used for this study. To contain the amalgam on the tooth surface, cylindrical plastic molds were placed on the dentin and secured with sticky wax. The bonding agents were then applied according to the manufacturers' instructions or light activated and Tytin amalgam was condensed into the plastic molds. The samples were thermocycled and shear bond strengths were determined using an Instron Universal Testing Machine. Analysis by one-way ANOVA indicated significant difference between the five groups (P < 0.05). The bond strength of amalgam to dentin was significantly higher with Amalgambond Plus using the High-Performance Additive than with the other four bonding agents.

Bond strength and microleakage of current dentin adhesives

OBJECTIVES

The purpose of this in vitro study was to evaluate shear bond strengths and microleakage of seven current-generation dentin adhesive systems.

METHODS

Standard box-type Class V cavity preparations were made at the cemento-enamel junction on the buccal surfaces of eighty extracted human molars. These preparations were restored using a microfill composite following application of either All-Bond 2 (Bisco), Clearfil Liner Bond (Kuraray), Gluma 2000 (Miles), Imperva Bond (Shofu), OptiBond (Kerr), Prisma Universal Bond 3 (Caulk), Scotchbond Multi-Purpose (3M), or Scotchbond Dual-Cure (3M) (control). Lingual dentin of these same teeth was exposed and polished to 600-grit. Adhesives were applied and composite was bonded to the dentin using a gelatin capsule technique. Specimens were thermocycled 500 times. Shear bond strengths were determined using a universal testing machine, and microleakage was evaluated using a standard silver nitrate staining technique.

RESULTS

Clearfill Liner Bond and OptiBond, adhesive systems that include low-viscosity, low-modulus intermediate resins, had the highest shear bond strengths (13.3 +/- 2.3 MPa and 12.9 +/- 1.5 MPa, respectively). Along with Prisma Universal Bond 3, they also had the least microleakage at dentin margins of Class V restorations.

SIGNIFICANCE

No statistically significant correlation between shear bond strength and microleakage was observed in this study. Adhesive systems that include a low-viscosity intermediate resin produced the high bond strengths and low microleakage. Similarly, two materials with bond strengths in the intermediate range had significantly increased microleakage, and one material with a bond strength in the low end of the spectrum exhibited microleakage that was statistically greater. Thus, despite the lack of statistical correlation, there were observable trends.

Silica contamination of etched dentin and enamel surfaces: a scanning electron microscopic and bond strength study

Most acid-etchant gels are thickened with silica, which can leave a particulate residue on dentinal surfaces. Some newer etchants are thickened with polymers, which reportedly leave no surface residue. This study used scanning electron microscopy to examine dentinal and enamel surfaces that had been etched with either silica- or polymer-thickened gels. The silica gels left particulate debris on dentinal surfaces, and this debris was not removed by rinsing with water. There was little evidence of this contaminant on enamel surfaces. Enamel and dentinal surfaces treated with the polymer-thickened gels appeared to be clean and uncontaminated. Shear bond strengths of composite resin to enamel and dentin etched with the different types of gel etchants were also evaluated. Silica contamination did not adversely affect bonding. In fact, etching with silica-thickened gels resulted in slightly higher bond strengths to both substrates. However, the differences were not statistically significant.

Effects of chlorhexidine on dentin surfaces and shear bond strengths

This in vitro study examined the effects of chlorhexidine on dentin surfaces and on the bond strengths of composite to dentin. Scanning electron microscopy revealed that the chlorhexidine solution deposited debris on the surface and within the tubules of etched dentin but chlorhexidine had no significant effect on the shear bond strengths of composite to dentin using the All-Bond 2 adhesive system.

In vitro bond strengths and SEM evaluation of dentin bonding systems to different dentin substrates

In comparison to enamel, bonding to normal dentin is a greater challenge because of its organic constituents, fluid-filed tubules, and variations in intrinsic composition. Bonding to sclerotic dentin is even more difficult. To evaluate the shear bond strengths of four adhesive systems to dentin substrates with different levels of mineralization, 120 extracted human teeth were randomly assigned to three groups (n = 40). After mid-coronal dentin was exposed, groups of specimens were artificially hypermineralized by immersion in a remineralizing solution, demineralized by means of an acetic acid demineralizing solution, or stored in distilled water to model sclerotic, carious, and normal dentin, respectively. Resin composite was bonded to dentin by use of commercial adhesive systems. After the specimens were thermocycled, shear bond strengths were determined in an Instron universal testing machine. Dentin substrates and resin/dentin interfaces were examined by SEM. For each adhesive system, the mean shear bond strength to normal dentin was significantly higher than that to either of the other substrates. Shear bond strengths to hypermineralized dentin were significantly higher than those to demineralized dentin with all adhesives except Prisma Universal Bond 3.

SEM comparison of acid-etched, CO2 laser-irradiated, and combined treatment on dentin surfaces

Research into polymer systems capable of bonding to dentin and enamel have resulted in improved bond strengths that allow more conservative restoration and strengthening of teeth. However, pretreatment of the dentin and enamel of various sorts, including exposure to laser energy, have been espoused to enhance this bonding. This study investigated the effects of two pretreatments, acid and CO2 laser exposure, both alone and in combination, on the surface topography of prepared dentin specimens as observed by scanning electron microscopy. Eighteen dentin specimens were flat-sanded with 600 grit sandpaper and exposed to 10% maleic acid and CO2 laser both alone and in combination. SEM observation suggested that laser treatment prior to acid etching could increase the resistance of the smear layer to acid removal, that laser exposure after acid treatment could expose a porous topography suggestive of the underlying dentin inorganic structure by way of vaporization of the collagen surface left after acid demineralization, and that these effects varied in degree with the laser exposure energy.

Analysis of debond rates of resin-bonded prostheses

Debonding rates of 164 resin-bonded prostheses (RBP) placed from 1974 to 1985 were examined at recall. The yearly debond rates were calculated, the cumulative probability of failure was determined for the debonded RBPs, and Weibull distribution parameters were determined. For perforated prostheses, there was a high initial debond rate, followed by slowly decreasing rates for about 5 years. Increasing rates after 5 years indicated the beginning of wear-out. The Weibull parameters for the wear-out period of the perforated prostheses were: characteristic life = 128 (SE = 2) months, modulus = 1.27 (0.06), and threshold parameter = 0. Data were available for etched frameworks for 6 years and showed decreasing debond rates during this time. The characteristic life of the etched bridges was 318 (84) months. The cumulative failure data were also modeled with a cubic polynomial distribution that resulted in a U-shaped hazard function.

Effects of curing tip distance on light intensity and composite resin microhardness

Recently, simple radiometers for measuring the intensity of dental curing lights have been introduced. This study examined the relationship among light intensity measurements by three radiometers, distance of curing tip from composite resin, and resin polymerization (as indicated by microhardness). Light intensity measurements, which decreased with increasing distance from the curing tip, were strongly correlated with composite resin hardness. Reduced light intensity produced softer composite resin, particularly on the bottom of specimens (2-mm depth). The different radiometers provided similar indications of the changes in light intensity at various curing distances.

A clinical study of nightguard vital bleaching

This double-blind, randomized, controlled clinical trial was designed to evaluate the efficacy and soft tissue effects of nightguard (mouthguard) vital bleaching. Subjects were assigned to one of two treatment groups, overnight (insertion of mouthguard at bedtime) or 3-hour (replenishment of test solution at hourly intervals for a total of 3 hours exposure daily). The experimental solutions included two products that are specifically designed for tooth bleaching, one product that is marketed as an oral antiseptic, and a control solution (glycerin). Each subject participated for a 3-week period. Tooth color analysis (shade determination) was done at baseline and the end of the treatment. Gingival and Plaque Indices were recorded at baseline and at the end of each week of study. Results indicated that the bleaching treatment was effective in most cases and caused no tissue inflammation or significant tooth sensitivity. The mean Gingival and Plaque Indices were generally lower (denoting improvement) at the end of treatment. Patient satisfaction with the procedure was high.

Effects of dentin permeability and hydration on the bond strengths of dentin bonding systems

This in vitro study evaluated the shear bond strengths of five adhesive systems bonded to dentin with and without simulated physiologic hydrostatic pressure. To simulate pulpal pressure, bonding procedures were done on extracted teeth connected to a hydration apparatus. Bond strengths were significantly less for each adhesive system under simulated physiologic conditions. Amalgambond had significantly higher bond strengths than Clearfil Photo Bond, Gluma, Scotchbond 2, or Tenure, either with or without simulated pulpal pressure.

Utilization of composite resins and direct bonding following periodontal treatment

When restoring dentition compromised by periodontal treatment, good aesthetics must be achieved without compromising the periodontal health. Improved composite resin systems and new dentin bonding agents offer excellent restorative options. The learning objective of this article is a review of composite resins and direct bonding for aesthetic restorations. Two cases are presented to illustrate the procedure.

Use of phosphoric acid etchants with Scotchbond Multi-Purpose

An earlier study showed that Scotchbond Multi-Purpose, which uses a 10% maleic acid dentin/enamel etchant, had lower enamel bond strengths than those typically obtained by etching with 35-40% phosphoric acid. Therefore, the possibility of substituting phosphoric acid for maleic acid in the Scotchbond system might be considered. The purpose of this study was to evaluate the dentin bond strengths of Scotchbond Multi-Purpose when various phosphoric acid agents were used to etch the dentin. Proximal dentin surfaces of extracted human molars were etched with 10% maleic acid, 35% phosphoric acid, 32% phosphoric acid, 10% phosphoric acid or 25% phosphoric acid with aluminum oxalate (Etch 'N' Seal). Scotchbond Multi-Purpose Primer and Adhesive were applied as directed and composite posts were bonded to the dentin. After thermocycling, the composite was fractured off using an Instron testing machine. Mean dentin bond strengths were 17.3 MPa for 10% maleic acid, 17.2 MPa for 10% phosphoric acid, 15.2 MPa for 35% phosphoric acid, 13.6 MPa for 32% phosphoric acid, and 5.2 MPa for Etch 'N' Seal. The bond strengths for all groups except Etch 'N' Seal were statistically similar.

Microleakage of amalgam restorations using Amalgambond and Copalite

This study compared the effect of using either Amalgambond as a cavity liner or Copalite in the reduction of microleakage in amalgam Class V restorations. Both retentive traditional and non-retentive cavity preparations were compared with gingival cavosurface margin locations both in enamel and in dentin. Cavity preparations were restored with their appropriate liner, thermocycled, and stored in erythrosin red stain for 10 days. The samples were then sectioned and degrees of microleakage determined. Statistical interpretation with the Wilcoxon test showed that microleakage was significantly greater (alpha = 0.05) with the non-traditional cavity design and with cavity margins located in dentin. The results also showed that Amalgambond as a cavity liner significantly reduced microleakage when compared to Copalite.

Single-tooth home bleaching

This article describes a simple but effective method of bleaching single vital discolored teeth. The patient applies a viscous 10% carbamide peroxide gel in a plastic mouth-guard designed to confine the gel only to the discolored tooth. This method has been effective for lightening vital teeth with calcified pulpal spaces.

Colorimetric evaluation of the effect of porcelain opacity on the resultant color of porcelain veneers

The effect of porcelain veneer opacity on the resultant shade of a veneer-substrate system was evaluated colorimetrically. Three groups of porcelain discs were fabricated using shade A1 Ceramco G veneer porcelain diluted with 0%, 25%, or 50% translucent porcelain. The discs were luted to a shade C4 substrate using an untinted resin composite luting agent. A custom shade guide was fabricated. All samples were analyzed with a Chrome Meter using Munsell and CIE LAB notation. ANOVA showed significant differences (P less than .05) for each coordinate in both the Munsell and CIE LAB color space for all groups. The smallest delta E*ab for all groups was noted with shade tab C2. The resultant shade was neither the shade of the porcelain (A1) nor the substrate (C4). The data indicate that the translucent porcelain has as great or greater effect on the color coordinates of the veneer-substrate system as the substrate material.

Improved esthetics with a combined bleaching technique: a case report

This paper describes a clinical case in which a combination bleaching technique was used to improve the appearance of the patient's discolored anterior teeth. Enamel microabrasion was used first to remove superficial fluorosis stains. A home bleaching regimen was then used to lighten the overall shade of the teeth, which had appeared more yellow after microabrasion.

Bond strength of composite resin to enamel bleached with carbamide peroxide

Bleaching with 35 percent hydrogen peroxide causes enamel surface changes, which result in lower bond strengths of composite resin. Although a previous SEM study showed that home bleaching with 10 percent carbamide peroxide does not cause such surface changes, the results of our study indicate that carbamide peroxide bleaching reduces the shear bond strength of composite to etched enamel. Removal of surface enamel, however, restores bond strengths to normal levels.

Subjective evaluation of the effect of porcelain opacity on the resultant color of porcelain veneers

The effect of porcelain veneer opacity on the resultant shade of a veneer/substrate system was subjectively evaluated. Three groups of porcelain discs were fabricated using shade A1 Ceramco G veneer porcelain diluted with 0%, 25%, or 50% translucent porcelain. The discs were luted to a shade C4 substrate using an untinted composite resin luting agent. Clinicians were instructed to match samples with a custom and a commercial shade guide, and to sort veneers into groups of similar shade. The Farnsworth-Munsell 83 Hue test was used to measure the clinicians' color vision. Results indicated that the participants were unable to distinguish any difference between veneer groups (kappa = 0.33). Shade C2 was the predominant shade chosen for all groups. All veneers provided some masking of the underlying substrate. Varying the percentage of translucent porcelain had little effect on the final shade assessment.

Microleakage of seven dentin bonding agents

The purpose of this study was to evaluate the ability of seven dentin bonding agents to reduce dye penetration at the margins of microfill composite restorations in dentinal cavities. Forty extracted molars were selected and cleaned. Cavity preparations were made in dentin with #55 carbide burs. The preparations were restored with Silux after application of one of the following dentin bonding agents: Gluma, Scotchbond 2, Tenure, Prisma Universal Bond 2, Mirage-Bond, XR Bond, and All-Bond. Samples were thermocycled for 200 cycles between 3 degrees C and 60 degrees C, then immersed in a 0.05 percent crystal violet solution for 2 hours. The samples were embedded in clear casting resin, sectioned, and examined with a light microscope. Our results indicated that the dentin bonding systems reduced, but failed to totally eliminate, microleakage around the composite resin restorations.

Effect of retention grooves on fracture strength of Class 2 composite resin and amalgam restorations

The effect of approximal retention grooves on fracture strengths of class 2 composite resin and amalgam restorations was tested in vitro. Results indicated that retention grooves significantly improved (P less than 0.05) the compressive strength of amalgam restorations (38.6% stronger). For posterior composite resin restorations, there was no significant difference in mean compressive strength of restorations in preparations with and without retention grooves.

Cast metal, resin-bonded prostheses: a 10-year retrospective study

A sample of 99 resin-bonded prostheses placed over a 10-year period were examined by four clinicians using a standardized criteria sheet. Areas examined included hard tissues, periodontium, retainer and pontic design, retention, the effect of occlusion on framework design and retention rate, and bonding media. The data from 7- and 10-year retrospective studies were compared for meaningful trends. Results showed (1) caries on retainer teeth was 3%, (2) gingival index of the retainer teeth was less than the gingival index of the rest of the mouth (0.7 +/- 0.5 versus 0.9 +/- 0.6), (3) the respective mean probing depths of retainer teeth of 34 patients in the 7- and 10-year studies were 2.2 +/- 0.4 mm and 1.9 +/- 0.7 mm, (4) the debond rate of all the prostheses from all causes was 31%, (5) the debond rate comparing etched metal and perforated retainers from all causes was 32% and 31% [corrected], respectively, and (6) 83% liked the prosthesis; 17% were noncommittal. The authors concluded that the resin-bonded prosthesis may be considered a permanent restoration and a valuable asset in the clinician's armamentarium.

Fracture resistance of endodontically prepared teeth using various restorative materials

This study compares the fracture resistance of endodontically treated premolars with modified types of cavity preparations and restoration with either amalgam or composite resin. The greatest influence on fracture resistance was the remaining tooth structure. The effect of adequate wall support on tooth strength was compared with intact unprepared teeth.

A conservative postorthodontic treatment of enamel stains

The purpose of this presentation is to describe a method used to remove or improve superficial stains in the enamel including mild decalcification present before and after orthodontic therapy. This procedure is only successful in the treatment of stains involving the outer enamel surface and is not effective for treating generalized pigmentation of the enamel and/or dentin. A step-by-step approach for the removal of the superficial enamel stains is presented.

Effects of polymerization techniques on uniformity of cure of large-diameter, photo-initiated composite resin restorations

The polymerization effectiveness of various methods of exposing large-diameter, light-activated composite resin samples is reported. Results of Knoop hardness testing showed that highest mean hardness was achieved by using a wide tip (13 mm) with either the spot cure or overlap method for 60 seconds. More uniform hardness resulted from the wide-tip with scanning methods and 60-second cure than resulted from the narrow-tip (8 mm) with the spot or overlap method and 20-second cure.