Effect of several bleaching agents on teeth stained with a resin-based sealer

AIM

To evaluate the effect of peroxide-based bleaching agents on teeth stained with AH26 sealer (Dentsply De Trey, Konstanz, Germany), using digital images and computer analysis.

METHODOLOGY

Thirty-five maxillary central incisors were root filled, and the internal walls of the access cavity were coated with AH26 sealer. Internal bleaching commenced 4 months after the root fillings. In three experimental groups (n = 10), the teeth were bleached for 21 days using 45% carbamide peroxide (CP) gel, 45% sodium perborate + carbamide peroxide (SP + CP) or sodium perborate + distilled water (SP + W). No bleaching was undertaken in the control group. Digital images of each specimen were made before treatment, 4 months after endodontic treatment and 2 weeks after bleaching. Colour differences (∆E) were calculated by determining L*a*b* values using digital images and imaging software. Differences between the original colour and sealer-stained teeth, between sealer-stained and bleached teeth and between original colour and bleached teeth were calculated. Data were analysed using one-way anova and Duncan tests (α = 0.05).

RESULTS

Colour differences between baseline and sealer staining were in the range of 8.1-9.9, but differences between the groups were not significant. After bleaching, the degree of lightening was essentially identical for the carbamide peroxide and sodium perborate + carbamide peroxide groups, but was significantly greater (P < 0.05) in these two groups than in the sodium perborate + water group.

CONCLUSION

For bleaching AH26 sealer-stained teeth, carbamide peroxide gel and carbamide peroxide gel mixed with sodium perborate were equally effective and significantly better than sodium perborate mixed with water.

Surface modification for enhanced silanation of zirconia ceramics

OBJECTIVE

The overall goal of this research was to develop a practical method to chemically modify the surface of high strength dental ceramics (i.e. zirconia) to facilitate viable, robust adhesive bonding using commercially available silanes and resin cements.

METHODS

Investigation focused on a novel approach to surface functionalize zirconia with a Si(x)O(y) "seed" layer that would promote chemical bonding with traditional silanes. ProCAD and ZirCAD blocks were bonded to a dimensionally similar composite block using standard techniques designed for silica-containing materials (silane and resin cement). ZirCAD blocks were treated with SiCl4 by vapor deposition under two different conditions prior to bonding. Microtensile bars were prepared and subjected to tensile forces at a crosshead speed of 1 mm/min scanning electron microscopy was used to analyze fracture surfaces and determine failure mode; either composite cohesive failure (partial or complete cohesive failure within composite) or adhesive failure (partial or complete adhesive failure).

RESULTS

Peak stress values were analyzed using single-factor ANOVA (p<0.05). Microtensile testing results revealed that zirconia with a surface treatment of 2.6 nm Si(x)O(y) thick "seed" layer was similar in strength to the porcelain group (control). Analysis of failure modes indicated the above groups displayed higher percentages of in-composite failures. Other groups tested had lower strength values and displayed adhesive failure characteristics.

CONCLUSION

Mechanical data support that utilizing a gas-phase chloro-silane pretreatment to deposit ultra-thin silica-like seed layers can improve adhesion to zirconia using traditional silanation and bonding techniques. This technology could have clinical impact on how high strength dental materials are used today.

Clinical Evaluation of an All-in-one Adhesive in Non-Carious Cervical Lesions with Different Degrees of Dentin Sclerosis

Lower scores for marginal discoloration and adaptation were noted when an all-in-one self-etching adhesive was applied to non-carious cervical lesions and compared to a three-step total-etch adhesive.

A prospective clinical evaluation of electronically mixed polyvinyl siloxane impression materials: results from the prosthetic "SuperStudy"--a consumer evaluation

Polyvinyl siloxane (PVS) impression materials incorporating a polyether carbosilane wetting agent and mixed with an electronic mixing system (Pentamix) were clinically compared with traditionally delivered (i.e., automixed) PVS impression materials during routine use by 1,505 general and specialized dental practitioners evaluating more than 30,000 impressions. Each study participant selected 20 patients and used standard tooth-preparation procedures appropriate to the therapy required, supplied specific data on each case, and ultimately evaluated the marginal detail, fit, and success of the final restorations. The areas requiring evaluation upon completion of the final restorations were ranked between "excellent," "good," "poor," and "remake needed," among users of the PVS materials with the electronic mixing system. About 80% of the respondents rated the Pentamix system as easier to mix and deliver than the gun or hand-mixed systems and two thirds said it was faster to mix. The system also received high scores for hygienic delivery, ease of mixing, and clean-up.

Effects of demineralization depth on microtensile bond strength to human dentin

PURPOSE

To evaluate the effect of different phosphoric acid concentrations (10% and 37%) on the microtensile bond strengths (microTBS) of three dentin adhesive systems with different solvents (ethanol, acetone, or none).

MATERIALS AND METHODS

Eighteen third molars divided into six groups were ground flat to expose superficial dentin, which was polished to 600-grit. The bonding procedure was initiated using either of two phosphoric acid gels (10% and 37%). Three adhesive systems - Single Bond (SB), Prime & Bond NT (NT), and One Coat Bond (OC) - with different solvents (ethanol, acetone, or none, respectively) were used. After adhesive application, a cylinder of composite resin was built up. After 24 h water storage, each tooth was serially sectioned into thin rectangular sections (or "sticks") parallel to the long axis and with a mean cross-sectional area of 0.4 mm2. microTBS were determined using an Instron universal testing machine. Data were analyzed using two-way ANOVA and Duncan's test.

RESULTS

Mean bond strengths ranged from 66.1 MPa for 10%/ H3PO4 and SB to 43.8 MPa for 37% H3PO4 and OC. SB and OC tended to have slightly higher bond strengths when 10% H3PO4 was used. NT with 37% H3PO4 had a significantly higher microTBS (54.6 MPa) than NT with 10% H3PO4 (44.4 MPa).

CONCLUSION

Etching dentin with 37% H3PO4 resulted in a significantly higher mean microTBS for the acetone-based adhesive NT. For both the ethanol- and water-based adhesive (SB) and the solvent-free adhesive (OC), acid concentration did not significantly affect bond strength.

Maximizing esthetic results in posterior restorations using composite opaquers

After removal of caries or a faulty existing restoration in a posterior tooth, frequently the pulpal floor is a dark substrate. Composites are translucent by nature, and even the more opaque shades transmit nearly 60% of visible light, meaning that composites require a certain thickness to maintain their intended shade, especially if the underlying substrate is particularly dark. Depending on the intensity of the dark substrate, even relatively thick composite restorations may not be capable of disguising the discolored dentin underneath. The substrate absorbs a significant part of the light that would otherwise reflect toward the occlusal surface, and the restoration has a nonvital monochromatic grayish color. Opaquers and tints (color modifiers) may be extremely useful to overcome this situation. In this study, composite restorations were placed in extracted teeth to demonstrate that the final esthetic results rely upon the optical properties of the background as well as those of the composite material itself. Preparations with simulated dark pulpal floors were restored without the use of opaquers and tint modifiers. After tooth hydration, the final shade was recorded with photographs. The restoration was removed and a new restoration was placed, but this time with a technique involving opaquer and tints. This article compares and discusses the outcomes of these two procedures.

CLINICAL SIGNIFICANCE

This demonstration shows a simple technique that can help dentists obtain predictable esthetic results in their daily practice with posterior composite restorations.

Fabrication of direct fiber-reinforced posts: a structural design concept

As the clinician continues the quest for optimal functional and esthetic success of a tooth-restorative complex, the current selection of restorative materials and techniques may prove overwhelming. Although no single system provides the ideal restorative solution for every clinical circumstance, understanding of general design criteria and the components for the various post and core systems available allow the clinician to appropriately select the method and materials compatible with the existing tooth structure and desired result. This article provides a discussion of the various post and core systems, the methods and materials inherent in these systems, and general design principles. Using that basic information and clinical experience, the authors offer an alternative procedure for the rehabilitation of the intraradicular anatomy of the post-endodontic channel with a direct composite resin--the fiber-reinforced post and core system.

CLINICAL SIGNIFICANCE

Using improved restorative materials that stimulate the physical properties and other characteristics of natural teeth in combination with the proper design principles, the clinician can develop a tooth-restorative complex with optimal functional and esthetic results.

Effects of adhesive composition on microtensile bond strength to human dentin

PURPOSE

To evaluate the role of adhesive composition (solvent and filler content) on microtensile bond strength (muTBS) to human dentin.

MATERIALS AND METHODS

15 third molars were ground to expose superficial dentin, which was polished to 600-grit. The dentin was etched for 15 s with 37.5% phosphoric acid, rinsed, and blotted with tissue paper. The surface remained visibly moist for all specimens. The following adhesives were applied to the etched dentin according to manufacturers' directions: Single Bond (SB), experimental Single Bond (with filler) (ExpSB), Prime & Bond NT (NT), experimental Prime & Bond NT (without nanofiller) (ExpNT), and One Coat Bond (with filler) (OC). Each adhesive was applied to three teeth, and a cylinder of resin-based composite was built up on the occlusal surface. After 24-hour water storage, each tooth was vertically sectioned with a low-speed saw to produce a series of 0.7 mm slabs. Each slab was then sectioned to obtain "sticks" with a cross-sectional area ranging from 0.35 to 0.45 mm2. muTBS were determined using an Instron universal testing machine. Data were analyzed using one-way ANOVA, and Duncan's test.

RESULTS

For filled adhesives, mean bond strengths ranged from 57.9 MPa for ExpSB to 48.2 MPa for NT. The unfilled adhesives SB and ExpNT had mean bond strengths of 75.9 MPa and 38.7 MPa, respectively. Unfilled SB had a significantly higher mean bond strength than the experimental filled version. The ethanol-based adhesive SB had a significantly higher mean bond strength than either the nonvolatile solvent-based OC or the acetone-based NT.

Dentin bonding: what is the state of the art?

Currently, two approaches are available for bonding resin-based materials to dentin--total-etch and self-etch. The total-etch approach, using either a three-step or a two-step method, has been available for several years. Clinical studies have demonstrated excellent success rates for total-etch adhesives, but many clinicians report problems with postoperative sensitivity. The self-etch approach, which is relatively new to the US market, reduces the incidence of postoperative sensitivity. However, the long-term clinical performance of self-etch materials--particularly those that use a single solution to etch, prime, and bond--is not yet proven. This article provides an overview of the current options for bonding resin to dentin.

Effects of phosphoric acid and glutaraldehyde-HEMA on dentin collagen

The purpose of this study was to evaluate the effects of phosphoric acid (PA) and a proprietary glutaraldehyde-HEMA aqueous solution (Gluma Desensitizer; GD) on dentin collagen. Specimens of demineralized bovine dentin collagen were treated with either 37% or 50% PA for 1 or 5 min. An additional set of specimens was treated with 37% PA for 1 min followed by GD for 1 min. All specimens were washed with distilled water, lyophilized. reduced with standardized NaB3H4, hydrolyzed with 6 M HCl and subjected to amino acid and cross-link analyses. The results demonstrated that the treatment of demineralized dentin with PA under the conditions tested did not significantly alter the collagen cross-links. The GD-treated samples showed reduction of free lysine (Lys) and hydroxylysine (Hyl) residues, as well as a decrease in the levels of collagen reducible cross-links. In addition, unidentified reducible compounds were detected by high-performance liquid chromatography (HPLC) analysis. These compounds may be derived from cross-links formed between GD-derived aldehyde and Lys/Hyl of collagen. The findings indicate that PA treatment does not significantly affect dentin collagen amino acid and cross-link composition, and that GD treatment affects dentin collagen amino acid and cross-link composition.

Clinical evaluation of two one-bottle dentin adhesives at three years

BACKGROUND

The method currently used to adhere resin to dentin involves etching, priming and bonding. Many commercial adhesives now combine priming and bonding functions in a single solution, and these are frequently called one-bottle adhesives. The purpose of this study was to compare the 36-month clinical performance of two commercial one-bottle adhesives.

METHODS

The authors enrolled 33 patients with noncarious cervical lesions in the study. A total of 101 lesions were restored with either a filled, ethanol-based adhesive (OptiBond Solo, SDS Kerr) or an unfilled, acetone-based adhesive (Prime & Bond 2.1, Dentsply Caulk) and a hybrid resin-based composite. Enamel margins were not beveled, and no mechanical retention was placed. The restorations were evaluated at baseline and six months, 18 months and 36 months after placement using modified Cvar/Ryge criteria.

RESULTS

The retention rates at 36 months were 93.3 percent for the ethanol-based adhesive and 89.4 percent for the acetone-based adhesive. The difference in retention rates was not statistically significant. In both groups, 12 percent of the retained restorations had marginal staining, but no recurrent caries was detected around any restoration. Other restoration characteristics such as marginal adaptation and color match remained excellent three years after placement.

CONCLUSIONS

The performance of both adhesives was excellent during this 36-month clinical trial. At the most recent recall evaluation (that is, 36 months), the filled, ethanol-based adhesive exhibited slightly better bond durability, but the difference between the two materials was not statistically significant.

CLINICAL IMPLICATIONS

The one-bottle adhesives evaluated in this study provided excellent clinical retention of Class V restorations without mechanical retention. When the materials are used properly, restorations are retained at a high rate during at least three years of clinical service.

Dentin bond strengths as a function of solvent and glutaraldehyde content

PURPOSE

To evaluate the effect of the inclusion of glutaraldehyde on the shear bond strength of new ethanol-based adhesives (Gluma Comfort Bond & Desensitizer, GCBD and Gluma Comfort Bond, GCB) versus acetone-based Gluma One Bond (GOB) and a conventional three-step adhesive as a control.

MATERIALS AND METHODS

Forty bovine incisors were mounted in acrylic, polished to 600-grit, and randomly assigned to four groups (n=10). Dentin was etched for 15 s using 35% phosphoric acid, rinsed, and lightly dried. After adhesive application and curing, Charisma composite was applied in a #5 gelatin capsule and light-cured. Specimens were loaded in shear using an Instron at 5 mm/min. Shear bond strengths were calculated by dividing failure load by bonded surface area. ANOVA showed a significant difference in means at P< 0.01, so Tukey's test was used for pairwise comparisons.

RESULTS

Mean SBS (+/- SD, MPa) were: GOB: 8 (4.4)ab; GCB: 10 (4.4)ab; GCBD: 14 (6)bc; SBMP: 17.7 (6.4)c. Superscript letters indicate Tukey's homogeneous subsets (P< 0.05).

Effect of dental unit waterline biocides on enamel bond strengths

This study evaluated the effects of chemical biocides used to control dental unit waterline biofilm on the bond strength of resin to enamel. Sixty bovine teeth were randomly assigned to six treatment groups. One-way ANOVA revealed a significant difference in means (p < 0.001) and Tukey's multiple range test indicated that three of the experimental groups had significantly lower mean shear bond strengths than the control (p < 0.05). This finding suggests that dental unit waterline biocides may adversely affect adhesion of resin to enamel.

Free-electron laser etching of dental enamel

OBJECTIVE

The purpose of this study was to evaluate the Mark-III free-electron laser as a means of etching enamel surfaces, with potential application to resin bonding.

METHODS

The FEL was tuned to wavelengths ranging from 3.0 to 9.2 microm. Specific wavelengths that are resonantly absorbed by phosphates, proteins, and water were used. First, bovine enamel was polished and exposed to static FEL exposures. Lased enamel was examined using scanning electron microscopy (SEM). Additional bovine enamel specimens were exposed to FEL at similar wavelengths, but with rastering to create treated rectangular areas on each specimen. Surface roughness was evaluated using profilometry and atomic force microscopy (AFM). Composite was bonded to the lased enamel, and shear bond strengths were determined using an Instron universal testing machine. As a control, the surface roughness of, and shear bond strengths to, acid-etched enamel were determined.

RESULTS

Static FEL exposures caused changes in the enamel ranging from an etched appearance to pits, cracks, and frank cratering. The surface roughness of lased enamel was much greater than that of acid-etched enamel, and was qualitatively different as well. Shear bond strengths of resin to acid-etched enamel were significantly higher than bond strengths to lased enamel.

CONCLUSIONS

Under the conditions used in this study, the FEL did not offer a practical and effective method of etching enamel for resin bonding. However, the ability of the FEL to deliver many specific wavelengths makes it an interesting tool for further research of laser effects on tooth structure.

Shear bond strengths of one-bottle adhesives to oil-contaminated enamel

PURPOSE

To evaluate resin bond strength to enamel contaminated with handpiece oil.

MATERIALS AND METHODS

Bovine teeth were randomly assigned to six groups of 20 teeth each for treatment with one of six different bonding systems (five one-bottle and one multibottle). For each system, 10 enamel specimens were contaminated with handpiece oil before acid-etching and 10 were contaminated after acid-etching. The enamel was etched for 15 seconds using 35% phosphoric acid. Following adhesive application, composite resin was bonded using a gelatin capsule technique. Shear bond strengths from the two contaminated groups were compared to bond strengths to uncontaminated enamel obtained from a previous study that was performed by the same group of investigators, using the same facility, materials, and methods.

RESULTS

Two-way analysis of variance (ANOVA) showed that the factor "surface contamination" did not have a significant effect on bond strength (p > .542). The type of adhesive and the interaction of adhesive and surface contamination were significant (p < .0001 and p < .003, respectively). When oil was applied before etching, mean bond strengths ranged from 18.0 +/- 4.8 MPa for OptiBond SOLO (Kerr Corp., Orange, California) to 25.3 +/- 5.6 MPa for Tenure Quik with Fluoride (Den-Mat Corp., Santa Maria, California). With oil applied after etching, bond strengths ranged from 18.4 +/- 8.0 MPa for Tenure Quik with Fluoride to 27.4 +/- 5.4 MPa for Single Bond (3M Dental Products, St. Paul, Minnesota). For the same adhesive, comparing uncontaminated and "oil-before-etch" contaminated groups, the only statistically significant difference in bond strengths was for OptiBond SOLO: 21.8 +/- 4.0 MPa (uncontaminated) versus 18.0 +/- 4.8 MPa (oil before etch). Comparing uncontaminated and "oil-after-etch" groups, the only statistically significant difference was for Tenure: 24.5 +/- 5.7 MPa (uncontaminated) and 18.4 +/- 8.0 MPa (oil after etch).

Effects of different re-wetting techniques on dentin shear bond strengths

PURPOSE

For contemporary hydrophilic resin adhesive systems, bonding to dentin is improved if the substrate is maintained in a hydrated state following acid-etching. The purpose of this study was to compare the dentin shear bond strengths of two single-bottle adhesives (one acetone-based and one ethanol-based) applied under different etched-dentin conditions: dry, wet, or dry and re-wetted with different solutions.

MATERIALS AND METHODS

Bovine incisors (N = 120) were mounted in acrylic, polished to 600-grit, and randomly assigned to 12 groups (n = 10). Dentin was etched for 15 seconds using 35% phosphoric acid, rinsed, and either blot-dried, air-dried, or air-dried and re-wetted with different solutions (distilled water, Gluma Desensitizer, Aqua-Prep, and 5% glutaraldehyde in water). Two adhesives (Single Bond and Prime & Bond NT) were applied to each of the surface conditions following manufacturers' instructions. After adhesive application and curing, composite was applied in a No. 5 gelatin capsule and light-cured. Specimens were loaded in shear, using an Instron at 5 mm per minute. Shear bond strengths were calculated by dividing the failure load by the bonded surface area. Data were subjected to analysis of variance (ANOVA) and a post hoc Tukey test.

RESULTS

Mean shear bond strengths ranged from 12.5 to 26.6 MPa for Single Bond and from 5.6 to 14.7 MPa for Prime & Bond NT. Significant differences were found in both groups of materials (p < .001). The three highest mean bond strengths were obtained (in order) on dentin that was re-wetted with Gluma Desensitizer, re-wetted with Aqua-Prep, or never dried. Differences between these surface conditions were not statistically significant for either material.

Effects of restorative and adhesive curing methods on dentin bond strengths

PURPOSE

To evaluate the shear bond strengths of "one-bottle" adhesives to dentin when used with self-cured composite.

MATERIALS AND METHODS

100 bovine teeth were ground to expose superficial dentin, which was polished to 600-grit. The dentin was etched for 15 s with 35% phosphoric acid, rinsed, and blotted with tissue paper. The surface remained visibly moist for all specimens. The following adhesives were applied to the etched dentin according to manufacturers' directions: Scotchbond Multi-Purpose (in its visible light-cured [VLC] and self-cure modes) as a control, One-Step (VLC only), OptiBond Solo Plus (VLC only), Prime & Bond NT (VLC) and Prime & Bond NT Dual-Cure. For each adhesive, specimens were bonded with a self-cure composite, while 10 were bonded with a VLC composite as a control. After 24 hrs water storage, shear bond strengths were determined using an Instron universal testing machine. Data were analyzed using two-way ANOVA, Tukey's test, and Student's t-tests.

RESULTS

Using the light-cured composite, mean bond strengths ranged from 11.0 MPa for light-cured Prime & Bond NT to 26.3 MPa for OptiBond Solo Plus. Using the self-cure composite, mean bond strengths ranged from 0.0 for light-cured Prime & Bond NT to 21.4 MPa for One-Step. Two adhesives, light-cured Prime & Bond NT and OptiBond Solo Plus, had significantly lower bond strengths when used with the self-cure composite.

CLINICAL SIGNIFICANCE

Some "one-bottle" dentin adhesives may not provide acceptable bonding to tooth structure when they are used with self-cure composites.

Shear bond strengths of one-bottle adhesives to moist enamel

PURPOSE

This study evaluated bond strengths of six one-bottle bonding agents and a control (primer plus unfilled resin) to moist enamel.

MATERIALS AND METHODS

One-hundred and five bovine teeth were randomly assigned to seven groups of 15. Enamel was etched for 15 seconds with 35% phosphoric acid. Etched enamel was rinsed, and excess water was blotted with tissue paper. Following application of the adhesive, composite resin was bonded using a gelatin capsule technique. Shear bond strengths to enamel were determined using a universal testing machine (Instron Corp., Canton, Massachusetts).

RESULTS

Mean bond strengths ranged from 21.9 MPa for OptiBond Solo (Kerr Corp., Orange, California) to 29.6 MPa for Prime & Bond 2.1 (Dentsply/Caulk, Milford, Delaware). Prime & Bond 2.1 had a significantly higher mean bond strength than the other adhesives.

CLINICAL SIGNIFICANCE

The results of this study suggest that all of the one-bottle systems tested should provide clinically acceptable bonding to moist enamel.

Two-year clinical evaluation of tooth whitening using an at-home bleaching system

PURPOSE

The purpose of this study was to evaluate the 2-year effectiveness of a carbamide peroxide at-home bleaching gel used to provide tooth lightening treatment.

MATERIAL AND METHODS

Twenty-nine patients participated in the original study, during which they treated their maxillary teeth with a 10% carbamide peroxide gel nightly for 2 weeks. Shades were determined before and after treatment by comparison with a Vita shade guide. Twenty-four patients (a recall rate of 83%) were recalled for evaluation 2 years after the initial bleaching treatment. The shade of the maxillary incisors was evaluated and compared with shades before, immediately after, and at 6 months and 2 years after initial treatment. Data were analyzed using a repeated-measures analysis of variance.

RESULTS

At 2 years after bleaching with a 10% carbamide peroxide gel, the median shade was D2, a six-increment difference from the baseline median of D3. Twenty of 24 patients (83.3%) had a shade change of two or more units, which is the threshold value for bleaching efficacy using American Dental Association guidelines. The lightening result remained statistically significant (p < .0001) at 2 years.

CLINICAL SIGNIFICANCE

Although some reversal of the lightening effect occurs over time following the original bleaching treatment, loss of the lighter color appears to be gradual for most patients. Although the longevity of the lightening effect remains to be determined, this clinical trial indicates that the majority of patients have a satisfactory result 2 years after treatment.

Clinical evaluation of Prime & Bond 2.1 for treating cervical dentin hypersensitivity

PURPOSE

To evaluate the effectiveness of a "one-bottle" dentin adhesive for reducing or eliminating hypersensitivity in exposed cervical dentin.

MATERIALS AND METHODS

Eight patients with hypersensitive teeth were enrolled in this clinical trial. The hypersensitive teeth included a total of 22 premolars and anterior teeth with exposed cervical dentin that was sensitive to cold or other stimuli. A single layer of Prime & Bond 2.1, an acetone-based "one-bottle" adhesive, was applied to the cervical dentin and was light-cured. Sensitivity to compressed air and cold stimuli was determined immediately before and after treatment, and at periods ranging to 24 wks after treatment. Patient responses to the stimuli were timed, and were also evaluated by the use of a visual analogue scale.

RESULTS

Application of a single coat of Prime & Bond 2.1 significantly reduced cervical dentin hypersensitivity to both compressed air and cold stimuli immediately after treatment. The reduction in hypersensitivity remained significant at 24 wks after treatment.

Eighteen-month clinical evaluation of a filled and unfilled dentin adhesive

OBJECTIVE

The purpose of this study was to evaluate the performance of a filled (OptiBond Solo) and an unfilled (Prime & Bond 2.1) "one-bottle" adhesive in Class V restorations after 18 months of clinical service.

METHODS

Thirty-three patients with non-carious cervical lesions were enrolled in the study. A total of 101 lesions were restored using one of the adhesives and a hybrid composite resin. Enamel was not beveled, nor was any mechanical retention placed. The restorations were evaluated at baseline, and at 6 and 18 months after placement using modified USPHS criteria.

RESULTS

Cumulative 18-month retention rates were 93.6% for OptiBond Solo and 98.0% for Prime & Bond 2.1. The difference in retention rates was not statistically significant. For OptiBond Solo, the only notable problems were interfacial staining and marginal adaptation, both of which were less than ideal in 9% of restorations. Marginal problems were slightly less frequent for Prime & Bond 2.1 restorations, but the difference was not significant.

CONCLUSIONS

Both adhesives provided Class V retention rates exceeding the 18-month, full acceptance guidelines set by the American Dental Association. Any additional benefit provided by the use of a filled adhesive was not detected in this 18-month clinical trial.

Medium-viscosity polyether impression material: a case report

Polyethers are elastomeric materials commonly used for making precision impressions. They are hydrophilic, which facilitates the contact of the unset material with the intraoral tissue and the wetting of the impression by cast materials. The final hardness of this new impression material is reduced in an attempt to overcome rigidity of the set impression. A case is described involving the restoration of a fractured maxillary premolar and a single-phase impression technique using the new polyether impression material.

Effect of finishing technique on the microleakage and surface texture of resin-modified glass ionomer restorative materials

PURPOSE

The purpose of this study was to evaluate the effects of wet and dry finishing/polishing procedures on the microleakage and surface texture of resin-modified glass ionomer (RMGI) restorative materials.

MATERIALS AND METHODS

Class V cavity preparations were made at the cemento-enamel junction (CEJ) on the buccal and lingual surface of 30 extracted human molars. The teeth were restored in three groups of 10 (20 preparations in each group) using Fuji II LC and Vitremer, both RMGIs, and Fuji II, a capsulated conventional glass ionomer cement (control). One restoration per tooth was finished/polished with copious applications of water and the other was finished/polished without water. All restorations were finished/polished using a sequence of four abrasive disks. Finishing/polishing was initiated according to manufacturers' instructions-immediately after light-curing Fuji II LC and Vitremer, and 15min after placement for Fuji II. The specimens were thermocycled and subjected to a silver nitrate leakage test. Each tooth was sectioned buccolingually and examined with an optical microscope at 40x to determine the extent of microleakage at enamel and dentin margins. The data were subjected to a non-parametric statistical analysis. To evaluate surface roughness after polishing, three disks each of Vitremer and Fuji II LC were fabricated in Teflon molds. One disk of each material was not finished/polished (control). The others were finished/polished using Sof-Lex abrasive disks. One specimen of each material was kept wet during all finishing/polishing procedures, while the other was kept dry. Atomic force microscopy was used to determine the average roughness (R(a)) of the specimens.

RESULTS

For each material, microleakage at the enamel margin was very slight. Leakage of the conventional glass ionomer Fuji II was severe at dentin margins. Statistical analysis indicated that both Vitremer and Fuji II LC had significantly less leakage than Fuji II, and that Vitremer had significantly less leakage than Fuji II LC (p<0.05). Leakage at enamel margins was significantly less than at dentin margins. Differences related to wet and dry polishing were not statistically significant. Profilometry data indicated that polished specimens were rougher than those cured against a Mylar strip. Wet polishing created greater surface roughness than dry polishing.

CONCLUSIONS

RMGIs rather than conventional glass ionomers should be used in Class V cavity sites to allow immediate finishing and to reduce the incidence of microleakage. Dry finishing of RMGIs with abrasive disks is recommended because it produces a smoother surface and does not contribute to microleakage. However, wet finishing of conventional glass ionomers is still recommended to avoid desiccation.

Packable composites: overview and technical considerations

OBJECTIVE

New composites, called packable or condensable composites, are being promoted as amalgam alternatives. The purposes of this review article are to identify these products, define new terminology associated with them, summarize the advertised properties for the materials, discuss the ideal properties for packable composites, review the properties of the major products, and critically evaluate the proposed handling procedures for these materials.

REVIEW

The term packable is preferable to condensable for describing this new class of materials. All materials should be considered amalgam alternatives, not amalgam substitutes. The compositions and physical properties reported by manufacturers reveal that none of the materials represents a remarkable improvement over the properties of more traditional universal composites. The designs of Solitaire (Heraeus Kulzer), ALERT (Jeneric-Pentron), and SureFil (Dentsply/Caulk) are discussed in detail. The distinguishing characteristics of all packable compositions are less stickiness or stiffer viscosity than conventional composites, which allow them to be placed in a manner that somewhat resembles amalgam placement.

CONCLUSIONS

Packable composites may allow more convenient placement in posterior sites and may offer some technique advantages over conventional composites. However, there is no evidence that their clinical properties are consistently better than those of conventional universal composites.

CLINICAL SIGNIFICANCE

Packable composites may be selected as alternatives to amalgam or conventional universal composites, but they are not equal to or better than dental amalgam in all respects. Also, in most cases, mechanical properties of packable composites are not substantially better than those of most conventional universal composites.

Bond strengths of new simplified dentin-enamel adhesives

PURPOSE

To compare the in vitro shear bond strengths (SBS) of five simplified dentin adhesives. The tested hypothesis was that the recently introduced simplified adhesive systems would have similar or higher SBS than an existing simplified acetone-based adhesive used as a control.

MATERIALS AND METHODS

100 flat bonding sites were polished to 600-grit on the labial surface of bovine incisors mounted in acrylic resin. 50 teeth were ground to expose enamel, while the remaining 50 specimens were prepared to expose middle dentin. The specimens were randomly divided into five equal groups to be treated with simplified dentin adhesives: Dentastic Uno, EasyBond, Gluma One Bond, One Coat Bond, and One-Step (control). A composite post was bonded to each treatment area. After thermo-cycling, enamel and dentin shear bond strengths were determined using an Instron testing machine and the data were submitted to statistical analyses.

RESULTS

Mean enamel bond strengths ranged from 14.6-28.4 MPa. One Coat Bond had the highest mean enamel SBS, but it was not significantly higher than those of Gluma One Bond and Dentastic Uno. EasyBond and One-Step had statistically similar mean enamel SBS and these were significantly lower than the mean enamel SBS of the other three adhesives. For dentin, mean SBS ranged from 14.8-21.7 MPa. Dentastic Uno had the highest mean dentin SBS, but it was not significantly greater than those of One Coat Bond and Gluma One Bond. Although One Step had the lowest mean dentin SBS, it was not significantly different from those of either EasyBond or Gluma One Bond.

Effects of repeated use on bond strengths of one-bottle adhesives

OBJECTIVE

Most one-bottle adhesives contain organic solvents (acetone or ethanol) that displace the water entrapped within the network of collagen fibers in etched dentin. Acetone and ethanol are volatile substances that could easily evaporate from bottles during use. The objective of this in vitro study was to assess the effects of repeated opening of bottles on dentin shear bond strengths of 4 adhesives.

METHOD AND MATERIALS

Eighty freshly extracted bovine incisors were mounted, polished to 600 grit, and randomly assigned to 8 groups (n = 10). After the application of the materials to 40 specimens at baseline, adhesive use was simulated by opening bottles for 1 minute, 2 times a day, for 3 weeks, except during weekends, when the bottles were kept refrigerated. After 3 weeks of simulated use, the same adhesives were applied to 40 additional specimens. Resin composite was applied to dentin in a No. 5 gelatin capsule and was light-cured. After 500 thermal cycles (5 degrees C to 55 degrees C), shear bond strength testing was performed with a universal testing machine at 0.5 cm/min.

RESULTS

Adhesives containing ethanol or water had similar mean bond strengths at baseline and at 3 weeks. The acetone-based material had a significantly lower mean bond strength at 3 weeks than at baseline.

CONCLUSION

Acetone-based adhesives may have a shorter useful life than ethanol- and water-based adhesives.

Fluoride release from restorative materials and its effects on dentin demineralization

As the use of adhesive restorative materials has increased during the last several years, interest in adhesive materials that release fluoride has also grown. The purpose of this study was to measure fluoride release from several adhesive restorative materials and to evaluate its effect on dentin resistance to demineralization and on bacterial metabolism in a modified in vitro system. Standardized cavities (1.8 mm in diameter) were prepared in bovine teeth that had been ground to dentin. One cavity in each tooth was restored with one of the following restorative systems: (a) Single Bond and Z100; (b) Single Bond and Tetric Ceram; (c) Fuji Bond LC and Z100; (d) Fuji Bond LC and Tetric Ceram; (e) Fuji II LC; or (f) Fuji IX GP. The other cavity in each tooth was "restored" with wax as a control. For each restorative system, 12 specimens were evaluated for fluoride release during the first 24 hrs after restoration placement. Dentin adjacent to the restored sites was subjected to lactic acid challenge (pH 4.3) for 3 hrs, after which calcium release was measured. Another 12 specimens in each group were stored for 24 hrs in de-ionized water, and were exposed to an S. mutans suspension (1:1 THB/de-ionized water and 50 mM glucose, A660 = 0.2) for 6 hrs, followed by calcium release and pH measurement. Bulk specimens of each material were also made and stored in water. Fluoride released from Fuji Bond LC, Fuji IX GP, and Fuji II LC in bulk was significantly greater than from the other materials. In the restored dentin specimens, increased resistance to demineralization from a lactic acid challenge was directly related to fluoride release. The same effects were seen as a result of the S. mutans challenge. While fluoride release from restorative materials increased the resistance of dentin to demineralization in this system, the clinical relevance of the findings is not known.

Treatment options for the exposed vital pulp

The exposure of dental pulp generally occurs as the result of accidental trauma or preparation techniques utilized during the restoration of carious lesions. While frank carious exposures are optimally treated with pulpectomy and root canal therapy, the ideal treatment of mechanically exposed pulps has remained controversial. This article describes the indications, clinical techniques, and prognosis for direct pulp capping and partial pulpotomy.

Ultra-morphological study of the interaction of dental adhesives with carbamide peroxide-bleached enamel

PURPOSE

To evaluate the effects of a carbamide peroxide bleaching agent on interfaces formed by two one-bottle dental adhesives to etched enamel. The null hypotheses tested in this study were that vital bleaching with a commercial 10% carbamide peroxide gel would not (1) increase the concentration of oxygen in the superficial layer of enamel or (2) induce ultra-morphological changes in resin-enamel interfaces.

MATERIALS AND METHODS

Five extracted human incisors were treated with 10% carbamide peroxide (Opalescence) for 4 h/day for 1 week and were compared with non-bleached teeth for oxygen, calcium, and phosphorus relative concentration using EDS. Mean elemental concentrations were analyzed using a t-test (bleached vs. unbleached enamel), one-way ANOVA (for surface location and also for depth) and three-way ANOVA (with bleaching treatment, surface location, and depth as the main factors). For TEM, fifteen extracted human molars were sectioned to obtain two crown halves. After roughening the occlusal surface, one half was bleached with Opalescence while the other half was stored in artificial saliva for 1 week. Enamel was etched for 15 s with a 35% phosphoric acid and bonded with one of three adhesives (Prime & Bond 2.1, Syntac Single-Component, or Scotchbond Multi-Purpose Adhesive-control) and a composite resin (Protect Liner F). Small enamel/resin sticks with a cross-section of 1.0 mm x 1.0 mm were removed and the specimens were processed for TEM observation.

RESULTS

Vital bleaching with 10% carbamide peroxide caused no significant changes in relative oxygen concentration of enamel. For calcium and phosphorus, bleaching resulted in significant decreased relative concentrations. Bleaching also resulted in morphological alterations in the most superficial enamel crystallites. Some altered crystallites exhibited electron-lucent cores and reduced thickness of material around the core.

Effect of polymerization mode on bond strengths of resin adhesive/cement systems

PURPOSE

The purpose of this study was to examine the effect of resin adhesive/cement system primer and cement polymerization mode (auto- vs dual-polymerized) on the shear bond strength to dentin.

MATERIALS AND METHODS

Dentin surfaces of 90 bovine teeth were polished to 600 grit. The dentin was etched for 15 seconds with phosphoric acid, rinsed, and blotted. Three adhesive systems, All-Bond 2, Prime & Bond 2.1 Dual-Cure, or Scotchbond Multi-Purpose Plus, were applied. Three primer polymerization methods were used with each system: dual-polymerized, autopolymerized, or strictly following manufacturers' recommendations. Resin cements, which were also either auto- or dual-polymerized, were applied to dentin using gelatin capsules. Shear bond strengths were determined using an Instron universal testing machine.

RESULTS

The greatest bond strength, 15.4 MPa, was found with the Scotchbond system when the primer was dual-polymerized and the cement was autopolymerized. The lowest bond strength, 7.5 MPa, was found with All-Bond 2/Duo-Link, when the primer and cement were dual-polymerized. The autopolymerization mode produced the highest mean bond strength for All-Bond 2, while dual-polymerization of primer and cement resulted in the highest mean bond strength for Prime & Bond 2.1. Scotchbond Multi-Purpose Plus was least affected by the polymerization method. Two-way ANOVA showed that the interaction between the type of adhesive system and the method of polymerization significantly influenced bond strength (p = .0001).

CONCLUSIONS

The effect of the primer polymerization method on ultimate bond strength was different for each adhesive system evaluated. More research is needed to elucidate the interaction between adhesive system and method of polymerization on bonding of resin cements to dentin.

Effect of a re-wetting agent on the performance of acetone-based dentin adhesives

PURPOSE

To compare the in vitro bond strengths of two acetone-based one-bottle dentin adhesives applied to four surface moisture conditions. The tested hypothesis was that wetting a dried dentin surface with an aqueous HEMA solution would result in bond strengths similar or higher than those obtained by leaving the surface moist as per manufacturers' instructions.

MATERIALS AND METHODS

Eighty flat dentin bonding sites were polished to 600-grit on middle dentin of the labial surface of bovine incisors mounted in acrylic resin. The specimens were equally and randomly divided between two acetone-based dentin adhesives (One-Step and Prime & Bond 2.1) and four different levels of surface moisture (moist dentin, dentin dried for 1 s, dentin dried for 5 s, and dentin dried for 5 s followed by re-wetting with Aqua-Prep, an aqueous HEMA solution). A composite post was then adapted to the treated area and light-cured. After thermocycling, the bond strengths were determined by testing the specimens in shear. Field Emission SEM examinations were carried out to evaluate the effects of different treatments on the dentin-resin interface.

RESULTS

Statistical analysis revealed that the application of One-Step resulted in similar mean shear bond strengths for the groups in which moisture was present on the dentin surface (12.0-14.2 MPa). The mean shear bond strengths for the group in which One-Step was applied to a dried dentin surface was significantly lower (6.0 MPa). For Prime & Bond 2.1, the application of a re-wetting solution significantly increased mean shear bond strengths (13.9 MPa). The remaining three Prime & Bond 2.1 groups yielded statistically similar mean bond strengths, regardless of the surface condition (6.6-8.1 MPa).

Effects of bleaching on teeth and restorations

This article describes how at-home bleaching procedures affect teeth and restorative materials. Specifically, it discusses the effects of tooth-whitening systems on enamel surfaces, enamel and dentin bond strengths, marginal integrity, color, and other properties of restorative materials.

Enamel bond strengths of "one-bottle" adhesives

PURPOSE

Several "one-bottle" dental adhesives recently have been introduced. These contain hydrophilic resin monomers that should readily wet tooth surfaces. Most also contain solvents that could increase enamel bond strengths by driving out residual moisture from enamel and increasing resin penetration. The purpose of this study was to evaluate bond strengths obtained by six one-bottle bonding agents and one conventional unfilled resin (control).

METHODS

Seventy bovine teeth were randomly assigned to seven groups of 10. Enamel was etched for 15 s with 35% phosphoric acid. Following application of the adhesive, composite resin was bonded using a gelatin capsule technique. Shear bond strengths to enamel were determined.

RESULTS

Mean bond strengths ranged from 14.2 MPa for Syntac Single-Component to 27.8 MPa for Single Bond. The mean for Syntac Single-Component was significantly less than that of all other systems tested.

CONCLUSION

The results of this study indicate that one-bottle bonding agents, with the exception of the Syntac material, provide enamel bond strengths at least equal to that of a conventional unfilled resin.

Bond strengths of conventional and simplified bonding systems

PURPOSE

To compare the shear bond strengths of composite to dentin using conventional (three-component) and simplified (two-component) adhesive systems.

MATERIALS AND METHODS

100 bovine teeth were mounted in phenolic rings and ground to 600-grit to obtain 90 flat facial dentin surfaces and 10 flat facial enamel surfaces. The dentin specimens were assigned to nine treatment groups of 10 teeth each. Three groups were assigned to conventional, three-component bonding systems: All-Bond 2, OptiBond FL, and Scotchbond Multi-Purpose Plus. Six groups were assigned to simplified, two-component bonding systems: Clearfil Liner Bond 2, Fuji Bond LC, One-Step, OptiBond Solo, Prime & Bond 2.1, and Tenure Quik with Fluoride. The enamel specimens were used as the control group with Scotchbond Multi-Purpose Plus Adhesive. Each ground surface was first conditioned according to the manufacturers' directions. After rinsing, the surface of each specimen was left visibly moist prior to application of the bonding system. Each bonding system was applied according to its manufacturer's directions. The corresponding composite restorative materials were applied in 4.4 mm diameter molds to the adhesive surface and light-cured from four directions. The completed specimens were stored in water 48 hours before testing. Shear bond strengths were measured using an Instron universal testing machine. Data were subjected to one-way ANOVA and Tukey's multiple comparison test.

RESULTS

Mean shear bond strengths of the conventional systems ranged from 16.3 to 20.6 MPa. Mean shear bond strengths of the simplified systems ranged from 14.7 to 17.4 MPa. The mean shear bond strength of the control (enamel bonding) was 21.4 MPa. The mean shear bond strengths of the conventional and simplified systems were not significantly different from each other or from the control system.

A characterization of first-generation flowable composites

A plethora of new low-viscosity composite resin materials, or flowable composites, have been marketed during the last two years, but little has been published about them. The authors describe research in which they compared the properties--filler, depth or cure, flow, wear, compressive strength, diametral tensile strength, indented biaxial flexure strength and toughness--of flowable and hybrid composites. Mechanical property tests (ISO 4049, ISO/DIS 6872) of eight flowable composites and two hybrid composites were conducted. The flowable composite with the least flow was similar to traditional composites. Mechanical properties were generally about 60 to 90 percent of those of conventional composites. The authors conclude that flowable materials should be used with caution in high-stress applications for restorative dentistry.

Clinical evaluation of two carbamide peroxide tooth-whitening agents

A blinded study was conducted to evaluate the efficacy and safety of a dentist-prescribed, accelerated carbamide peroxide tooth-whitening system. Fifty-one patients with discolored teeth completed a clinical trial using an overnight bleaching regimen. One group used an experimental bleaching (whitening) regimen with 10% carbamide peroxide bleaching paste, and another group used the Colgate Platinum Professional Overnight Whitening System. The study included an initial 1-week control/compliance phase using a placebo gel, followed by a 1-week active phase using the assigned bleaching agent. The shade of each participant's maxillary anterior teeth was evaluated by 2 trained and calibrated evaluators at the start of the control/compliance phase, the beginning of the active phase, and days 3, 5, and 7 of the active phase. A value-oriented Vita shade guide with 16 rankings was used to measure color changes, and the number of shade guide units of change (delta sgu) was calculated. Potential side effects, such as tooth hypersensitivity and gingival irritation, also were assessed at each recall examination, as well as recorded by the patients in their daily diaries. At the end of the 7-day active phase, the mean delta sgu for the group using the experimental bleaching agent was 7.1 +/- 2.4, and for the Colgate Platinum Overnight group, the delta sgu was 7.5 +/- 2.2. There were no statistically significant (p > or = 0.05) differences between the results of both groups at the 0-, 3-, 5-, and 7-day evaluations. After 7 days, the change in shade guide units for both groups ranged from 3 to 13 units, far exceeding the minimum required change by the American Dental Association Guidelines (delta sgu = 2 units) for demonstrating efficacy. There was no statistical difference in the whitening achieved at day 5 vs. day 7 for either tooth-whitening group. There were no notable changes in any gingival, bleeding, or plaque indexes for the 50 patients completing the active phase. The number of days of mild tooth sensitivity during the active phase was 0.9 +/- 1.3 days for the experimental agent group and 1.1 +/- 1.5 days for the Colgate Platinum group.

Bonding systems for restorative materials--a comprehensive review

The acid-etch technique for bonding composite resins to enamel has revolutionized the practice of pediatric restorative dentistry. Although bonding resins to dentin has proved to be a difficult challenge, ongoing advances have improved the reliability and predictability of dentinal adhesion. The purpose of this paper is to review the subject of dentin bonding; its development, current status, and clinical methods to improve performance.

Shear bond strengths of one-bottle dentin adhesives using multiple applications

This study evaluated the effect of multiple applications of the one-bottle adhesives Prime & Bond, One-Step, and Tenure Quik on the shear bond strength of composite to dentin. In addition, the study examined the effects of surface moisture and dual-cure composite on bond strengths of One-Step and Tenure Quik respectively. The adhesive systems were bonded to the occlusal dentin of extracted human teeth. Control group specimens received only two applications of adhesive, as recommended by the manufacturers. Two experimental groups of each system received a greater number of adhesive applications. Additional experimental groups using only two adhesive applications were made to test modifications in surface moisture and composite type for One-Step and Tenure Quik. Shear bond strengths were determined using an Instron Universal Testing Machine. The mean shear bond strength of the Prime & Bond control group was significantly greater than that of the other two control groups. Multiple applications of adhesive decreased the bond strength of each system, but the difference was significant only for four applications of One-Step. The method of moisture removal (compressed air or blotting) had no effect on shear bond strength of One-Step. The shear bond strength of Tenure Quik was not affected by the type of composite used. Prime & Bond had significantly higher shear bond strengths to dentin than either One-Step or Tenure Quik. Both Prime & Bond and One-Step had significantly higher bond strengths than Tenure Quik.

Bond strengths of a new dentin adhesive system

PURPOSE

This in vitro study evaluated the shear dentin bond strengths of EBS, a new three-component adhesive system containing an aqueous primer. Two other adhesive systems (Scotchbond Multi-Purpose and OptiBond FL) were included in the study for comparison. A simple tensile test and the effect of composite restorative material on shear bond strength were also evaluated.

MATERIALS AND METHODS

Eighty bovine teeth were obtained, embedded in acrylic, polished to 600 grit to form standardized dentin specimens, and randomly assigned to eight treatment groups. Resin composite was placed in gelatin capsules and bonded to dentin using the three adhesive systems. Each system was used according to manufacturers' instructions on dentin that was blotted to remain moist after etching. Each bonding system was used with its own manufacturer's composite material, and EBS and OptiBond FL were also used with a higher modulus composite, Z100. Specimens were stored in water for 24 hours, and bond strengths were determined using an Instron universal testing machine.

RESULTS

EBS/Pertac II had a mean shear bond strength of 17.2 MPa, which was significantly less than Scotchbond Multi-Purpose/Z100 (22.5 MPa) but similar to OptiBond FL/Herculite (16.4 MPa). Shear bond strengths of EBS and OptiBond were only slightly higher when they were used with Z100 composite. Tensile bond strengths were less than shear bond strengths but were nearly identical for all three systems (range: 8.0-9.8 MPa).