Publications by authors named "William W Brackett"

33 Publications

24 hour polymerization shrinkage of resin composite core materials.

J Esthet Restor Dent 2021 May 31. Epub 2021 May 31.

Director of Graduate Studies, University of Kentucky College of Dentistry, Lexington, Kentucky, USA.

Purpose: The study's purpose was to evaluate the 24-hour polymerization shrinkage of resin composite core materials.

Material And Methods: Eleven resin composite core material samples (n = 12) were evaluated using a non-contact imaging device with measurements obtained over 24 h. Shrinkage values were determined corresponding to proposed times involved with CAD/CAM same-day treatment and at 24 h. Shrinkage data was statistically compared using Friedman/Dunn's test for intragroup analysis and Kruskal Wallis/Dunn's test for intergroup analysis, all at a 95% level of confidence (α = 0.05).

Results: Mean results identified a wide volumetric shrinkage range with considerable similarity overlap. Inconsistent shrinkage behavior was evident and all materials reached maximum values before 24 h. No significant difference was observed during proposed digital same day all ceramic crown procedures, but some differences were noted at 24 h.

Conclusions: Under this study's conditions results were material specific, at times inconsistent, with wide variation. Shrinkage consistently increased for all products and it is not known if the continued shrinkage magnitude may compromise the stability and fit of all-ceramic crowns at 24 h.
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http://dx.doi.org/10.1111/jerd.12788DOI Listing
May 2021

Resin Bonding of a Lithium-Disilicate Crown Using a Ligated Rubber Dam: A 2-Year Case Report.

Compend Contin Educ Dent 2021 Apr;42(4):188-191

Professor, Department of Restorative Sciences, Dental College of Georgia, Augusta University, Augusta, Georgia.

Enduring glass-ceramic restorations greatly depend on the quality of adhesion of the crown to enamel and dentin. Proper isolation is vital to the success of bonded ceramic restorations. The rubber dam has long been considered the primary method of preventing contamination of the operating field, a crucial requisite for adhesion. However, many dentists do not use rubber dam isolation due to its penchant for slowing down procedures. The authors present a case report that describes a technique for the indirect bonding of a ceramic restoration to a maxillary first molar using rubber dam isolation in conjunction with a floss ligature,a method that is aimed at optimizing operator effectiveness and efficiency.
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April 2021

Minimally invasive esthetic improvement in a patient with dental fluorosis by using microabrasion and bleaching: A clinical report.

J Prosthet Dent 2018 Sep 1;120(3):323-326. Epub 2018 May 1.

Professor, Department of Restorative Sciences, Dental College of Georgia at Augusta University, Augusta, Ga.

Dental fluorosis is a condition that produces unesthetic coloration of enamel because of excessive fluoride ingestion during enamel formation. Its appearance can range in severity from mildly white and opaque to dark brown and can lead a patient to seek dental treatment. Historically, these lesions have been masked, either with direct or indirect restorations, but more conservative treatment options are now available, including the combination of microabrasion and bleaching. This clinical report describes the use of these treatment options to address a young patient's dental fluorosis.
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http://dx.doi.org/10.1016/j.prosdent.2017.12.024DOI Listing
September 2018

Restoration of Anterior Dental Erosion with a Combination of Veneers and Crowns: A 3-Year Case Report.

P R Health Sci J 2015 Dec;34(4):222-4

Professor, Department of Oral Rehabilitation, College of Dental Medicine, Georgia Regents University of Augusta, USA.

This report describes the conservative management of a 40-year-old female patient with smooth, eroded facial enamel affecting her maxillary anterior and some posterior teeth. Using conventional enamel bonding, pressed leucite-reinforced laminate veneers were used to restore the length, contour, and esthetics of the maxillary right canine, as well as of the right lateral and both central incisors; at the same time, it was necessary to restore the maxillary left lateral incisor, canine, and first premolar of the same quadrant with all-ceramic crowns of the same material. The patient has been followed for 3 years and demonstrates a good esthetic outcome with no shade discrepancy between the two types of restoration. Apparently, the tooth structure, though eroded, was able to provide an adequate bonding substrate for these adhesive restorations.
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December 2015

Effect of Sodium Fluoride on the endogenous MMP Activity of Dentin Matrices.

J Nat Sci 2015 Jun;1(6)

Department of Oral Biology, Georgia Regents University, College of Dental Medicine, Augusta, GA, USA.

Objectives: This study evaluated the effect of incorporating increasing concentrations of sodium fluoride in incubation media, on the loss of dry mass and solubilization of collagen from demineralized dentin beams incubated for up to 7 days. The effect of fluoride on the inhibition of matrix-bound metalloproteinases (MMPs) was also measured.

Methods: Dentin beams were completely demineralized in 10% phosphoric acid. After baseline measurements of dry mass, the beams were divided into six groups (n=10) and incubated at 37°C either in buffered media containing sodium fluoride (NaF) at 75, 150, 300, 450, 600 ppm or in fluoride-free media (control) for seven days. Following incubation, dry mass was re-measured. The incubation media was hydrolyzed with HCl for the quantitation of hydroxyproline (HYP) as an index of solubilization of collagen by endogenous dentin proteases. Increasing concentrations of fluoride were also evaluated for their ability to inhibit rhMMP-9.

Results: Addition of NaF to the incubation media produced a progressive significant reduction (p<0.05) in the loss of mass of dentin matrices, with all concentrations demonstrating significantly less mass loss than the control group. Significantly less HYP release from the dentin beams was found in the higher fluoride concentration groups, while fluoride concentrations of 75 and 150 ppm significantly reduced rhMMP-9 activity by 6.5% and 79.2%, respectively.

Conclusions: The results of this study indicate that NaF inhibits matrix-bound MMPs and therefore may slow the degradation of dentin matrix by endogenous dentin MMPs.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4457332PMC
June 2015

Film thickness of crown disclosing material and its relevance to cementation.

J Prosthet Dent 2014 Nov 31;112(5):1246-9. Epub 2014 Jul 31.

Professor, Department of Oral Rehabilitation, College of Dental Medicine, Georgia Regents University, Augusta, Ga.

Statement Of Problem: Regardless of the type of indirect restoration being fabricated, optimizing fit at cementation is a challenge. Several disclosing agents have been recommended to identify intaglio surface contacts that may result in incomplete seating and poorly adapted margins. The International Organization for Standardization has established a standard of 25 μm for the maximum film thickness for water-based cements. To accurately predict the clinical behavior of a luting cement, the disclosing agents themselves should have a film thickness no greater than 25 μm.

Purpose: The purpose of this study was to determine the film thickness of 2 disclosing products, a spray-on powder (Occlude Indicator Marking Spray) and a silicone disclosing agent (Fit Checker).

Material And Methods: The film thickness of the 2 disclosing products was determined by using optically flat glass cylinders according to the method set forth in International Organization for Standardization Standard 9917 for water-based cements. Because the silicone product is fast setting, the load was applied within 10 seconds of completing the mix. The spray-on product was allowed to dry before applying the load, in accordance with its intended clinical use. The film thickness of both products was determined with a load of 150 N applied for 30 seconds. Additional determinations were made for the silicone product at both 100 N and 50 N applied for 30 seconds and at 150 N applied for 90 seconds. An additional film thickness determination for the spray-on product was made with no load applied. The film thickness data for the various loads and intervals for the silicone product were analyzed with a 1-way ANOVA and the Tukey-Kramer multiple comparison test (α=.05). A t test (unequal variance, 2-tailed) was used to compare the spray-on and silicone products as measured at a load of 150 N applied for 30 seconds.

Results: The average film thickness of Fit Checker ranged from 16.7 to 23.7 μm, with the two 150-N groups significantly lower than the others, whereas that of Occlude was 67.7 μm unloaded and 48.4 μm when loaded. The film thickness of Fit Checker was significantly less than that of Occlude for the 150 N, 30-second group.

Conclusion: Within the limitations of this study design, Fit Checker had a film thickness that satisfied the 25-μm limit imposed on water-based luting cements in the International Organization for Standardization standard, whereas Occlude Spray did not.
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http://dx.doi.org/10.1016/j.prosdent.2014.06.005DOI Listing
November 2014

Four-year follow-up of the rehabilitation of a mandibular arch with a cementable zirconia-reinforced fixed dental prosthesis: a clinical report.

J Prosthet Dent 2012 Sep;108(3):138-42

Department of Oral Rehabilitation, College of Dental Medicine, Georgia Health Sciences University, Augusta, GA 30912, USA.

Implant-supported prostheses have been used extensively to rehabilitate completely edentulous arches. Although combinations of different restorative materials have reportedly been used to fabricate such prostheses, a metal framework is usually chosen for acrylic resin reinforcement. However, cost and the frequent need to section and solder to attain a passive framework fit are disadvantages for using metal. Zirconia has been used widely in restorative dentistry as an alternative to metal. This clinical report describes the fabrication of a zirconia-reinforced cementable fixed dental prosthesis with a 4-year follow-up.
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http://dx.doi.org/10.1016/S0022-3913(12)00120-5DOI Listing
September 2012

Cytotoxicity of endodontic sealers after one year of aging in vitro.

J Biomed Mater Res B Appl Biomater 2012 Oct 18;100(7):1729-35. Epub 2012 Jul 18.

Department of Oral Rehabilitation, Georgia Health Sciences University College of Dental Medicine, Augusta, Georgia, USA.

The in vitro cytotoxic response to endodontic sealers was assessed for one year. AH-Plus (AHP), Epiphany (EPH), EndoRez (ER), Guttaflow (GF), InnoEndo (IN), and Pulp Canal Sealer (PCS) were exposed to mouse osteoblasts and human monocytes after curing, 52 weeks of aging, and after resurfacing post-aging; cellular response was estimated by succinate dehydrogenase (SDH) activity. The effect of materials on TNFα secretion from activated (LPS) and inactivated monocytes also was measured. Cell responses were compared with ANOVA and Tukey post hoc analysis (α = 0.05). Initially, all materials except GF suppressed osteoblastic SDH activity compared with Teflon (Tf) controls. SDH activity in cells exposed to some aged sealers improved significantly; but IN and ER remained cytotoxic. When aged materials were resurfaced then tested, AHP, ER, GF, and IN did not change. EPH and PCS were more toxic. Monocytes responded similarly to the osteoblasts. No endodontic sealer activated monocytic TNFα secretion (p > 0.05 vs. -LPS Tf-controls). LPS-activated monocytes exposed to unresurfaced AHP and IN significantly suppressed TNFα secretion. When activated monocytes were exposed to the resurfaced sealers, differential suppression of TNFα secretion was observed for three of the four sealers tested (EPH, IN, and PCS). The results suggest that long-term aging may be a useful adjunct to in vitro assessment of these materials.
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http://dx.doi.org/10.1002/jbm.b.32739DOI Listing
October 2012

New method of measuring water permeability of adhesive resin films.

Am J Dent 2011 Feb;24(1):20-4

Department of Oral Rehabilitation, School of Dentistry, Medical College of Georgia, Augusta, Georgia 30912-1260, USA.

Purpose: To adapt a simple gravimetric method to measuring the permeability of adhesive resin films to liquid water, and to compare this to the water vapor permeability of the same resins.

Methods: Using commercially-available permeability cups designed for industrial permeability testing, the loss of mass of water vapor or liquid water from a stainless steel cup sealed with a resin film was measured over 1-2 days. The permeabilities of Parafilm (control), Clearfil SE Bond adhesive, Xeno IV and One-Up Bond F were compared.

Results: The lowest resin film permeability was obtained with Clearfil SE Bond adhesive films. The permeabilities ofXeno IV and One-Up Bond F to liquid water were 2.76 and 3.27-fold higher (P < 0.001) than that of Clearfil SE Bond adhesive. Liquid water permeability was always 2.8-3.8-fold higher (P < 0.05) than water vapor transmission rate. It was concluded that quantitative comparisons of the permeability properties of resin films can be made gravimetrically. The large permeability cups that are available commercially may be reduced in size in the future for measuring dentin adhesive films with smaller surface areas that are less liable to contain imperfections.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3816738PMC
February 2011

Two-year clinical performance of Clearfil SE and Clearfil S3 in restoration of unabraded non-carious class V lesions.

Oper Dent 2010 May-Jun;35(3):273-8

Department of Oral Rehabilitation, School of Dentistry, Medical College of Georgia, Augusta, GA, USA.

This study was undertaken to evaluate the two-year clinical performance of a self-etching primer and a self-etching adhesive, both of which employ the same acidic monomer. Forty pairs of restorations of AP-X hybrid resin composite (Kuraray Co, Ltd, Osaka, Japan) were placed in caries-free cervical erosion/abfraction lesions. Based on insensitivity to air, the dentin in 62% of these lesions was considered to be sclerotic. The restorations were placed with no abrasion of tooth surfaces, except for cleaning with plain pumice and no use of phosphoric acid etching, which is counter to the manufacturer's instructions that call for etching of unprepared enamel. One restoration from each pair was placed using Clearfil SE Bond, an adhesive employing a self-etching primer, and the other was placed using Clearfil S3 Bond, a self-etching adhesive. To emulate the results likely to occur in a private practice, the restorations were placed by well-educated, experienced clinicians who had no particular expertise in adhesive dentistry research and who placed the restorations according only to their interpretation of the manufacturer's instructions. The restorations were clinically evaluated at baseline and at 6, 12 and 24 months, using modified Ryge/USPHS criteria. For both products, retention of 81%-84% of the restorations was observed over two years, which is lower than has been previously observed with these products and is likely due to limitations in the manufacturer's instructions compounded by inexperience of the operators in adhesive dentistry research. One restoration placed with each adhesive demonstrated secondary caries, which was probably attributable to the study being conducted in a non-fluoridated area and which reduced the percentages of clinically successful restorations to 78%-81%. No statistically significant difference (p = 0.50) between the two adhesives was observed in overall performance.
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http://dx.doi.org/10.2341/09-266-CDOI Listing
July 2010

Minimally retentive gold onlays: a six-year case report.

Oper Dent 2009 May-Jun;34(3):352-5

Department of Oral Rehabilitation, School of Dentistry, Medical College of Georgia, Augusta, GA, USA.

Partial veneer gold restorations, such as gold onlays, have changed little in preparation design over the past 40 years, as evidenced by textbooks that have long been in print. Such designs must have been based on the assumption that restorations would be luted with zinc phosphate cement but have not altered, despite the introduction of stronger luting cement classes, such as resin composite and resin-modified glass ionomer cements. It is well-established that both porcelain and base metal materials, which have been etched on the intaglio surface, can be combined with resin composite luting cements to produce restorations retained largely through adhesion. However, neither of these materials can equal the combination of minimal tooth reduction and margin adaptation that is possible with high noble gold restorative materials. Although high noble gold alloys cannot be etched, air abrasion of the intaglio surface of restorations likely improves micromechanical retention, but it is unknown whether this, along with a strong luting cement, is sufficient to stabilize high noble gold alloys in preparations with considerably less retention and resistance form than traditional designs.
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http://dx.doi.org/10.2341/08-50DOI Listing
September 2009

Color differences: polymerized composite and corresponding Vitapan Classical shade tab.

J Dent 2009 18;37 Suppl 1:e34-9. Epub 2009 May 18.

Indiana University School of Dentistry, Indianapolis, IN 46037, USA.

Objectives: This study compared newer composite resin restorative materials to the Vitapan Classical tabs they purported to represent.

Methods: Five Vitapan Classical tabs were studied: A3.5, B2, C1, C3, and D2 (n=3). These tabs created a variety of levels of lightness, chroma and hue. Each of these five shade tabs was removed from three different shade guides, and an intraoral spectrophotometer was used to capture CIELAB color coordinates. Three separate readings were made and all nine were averaged. The inter-tab color differences were also calculated. Five specimens approximately 4.0mm thick were fabricated for each of the shades studied using five different composite resin materials. Composite specimens were of the same size and shape as target shade tabs, and three separate recordings were made for each of them. This average was compared to five Vitapan Classical shade tabs to calculate the color differences using both CIELAB and CIEDE2000 color difference formulas. Color differences were compared to thresholds for perceptibility and acceptability reported in other studies.

Results: CIELAB and CIEDE2000 color differences ranged from 3.9 to 22.8 and from 2.1 to 13.8, respectively. None of the materials proved, an acceptable CIELAB color match to any of the shades tested.

Conclusion: When various shade tabs of Vitapan Classical shade guides were compared with correspondent tabs made of direct restorative composites, no material/shade combination resulted in an acceptable mismatch relative to the used standard of acceptability. Therefore, evaluated resin composites exhibited poor match compared to target Vitapan Classical tabs.
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http://dx.doi.org/10.1016/j.jdent.2009.05.008DOI Listing
October 2009

Film thicknesses of recently introduced luting cements.

J Prosthet Dent 2009 Mar;101(3):189-92

Department of Oral Rehabilitation, School of Dentistry, Medical College of Georgia, Augusta, Ga 30912-1260, USA.

Statement Of Problem: A luting cement must maintain a minimum film thickness over a sufficient period of time to allow seating of indirect restorations. The performance of newer luting cements in this regard has not been evaluated.

Purpose: The purpose of this study was to compare the film thicknesses of 6 luting cements, 2 resin-modified glass ionomer (FujiCEM and RelyX Luting Plus), 2 composite resin (Panavia 21 and RelyX ARC), and 2 self-adhesive resin (Maxcem and RelyX Unicem) cements, over 3 minutes.

Material And Methods: The film thickness (microm) of each cement (n=7) was determined at room temperature at 1, 2, and 3 minutes after the start of mixing, according to the testing method set forth in ISO Standard 9917. Means of all cements were compared at the 2-minute interval, and means at the 1- and 3-minute intervals for each were compared to the mean for the same cement at 2 minutes, using 1-way analyses of variance (ANOVA) and Tukey-Kramer multiple comparison tests (alpha=.05).

Results: Except for 1 resin-modified material at 3 minutes, a point beyond its specified working time, all materials produced film thicknesses under 30 microm at 3 minutes and under 26 microm at 2 minutes.

Conclusions: All of the materials tested meet the ISO standard of 25-microm maximum film thickness for up to 2 minutes after mixing.
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http://dx.doi.org/10.1016/S0022-3913(09)60026-3DOI Listing
March 2009

Comparison of traditional and low sensitivity whiteners.

Oper Dent 2008 Jul-Aug;33(4):379-85

Department of Restorative Dentistry, Indiana University School of Dentistry, Indianapolis, IN 46202-5186, USA.

This placebo-controlled, double-blind randomized clinical trial compared five 10% carbamide peroxide tooth whitening formulations. Three products contained varying concentrations of potassium nitrate as desensitizers. One contained no desensitizers and one was a placebo. During the two weeks of active bleaching, participants used a daily diary to record the number of days of sensitivity from hot, cold, gums, tongue and/or throat. The total number of days of sensitivity experienced by the participants in each group was compared. Participants using the agent with no desensitizers did not experience any more sensitivity than those using the agent containing 3% potassium nitrate. The products that included 0.5% potassium nitrate and 0.5% potassium nitrate and 0.25% sodium fluoride were not associated with any more sensitivity than the placebo group. In addition, the shade tab change from baseline to 11 weeks following cessation of bleaching was compared. Using an active bleaching agent, no difference in color change was noted among the four groups. All four groups were associated with significantly higher color change than the placebo. The addition of a small percentage of potassium nitrate to a 10% carbamide peroxide tooth whitener was shown to significantly reduce postoperative sensitivity without reducing efficacy.
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http://dx.doi.org/10.2341/07-134DOI Listing
October 2008

The effect of subject age on the microtensile bond strengths of a resin and a resin-modified glass ionomer adhesive to tooth structure.

Oper Dent 2008 May-Jun;33(3):282-6

Department of Oral Rehabilitation, School of Dentistry, Medical College of Georgia, Augusta, USA.

In this study, the microtensile bond strengths of an etch-and-rinse resin adhesive to dentin and enamel and a resin-modified glass ionomer adhesive to dentin were determined on teeth known to have originated from subjects over 60 years of age. The same tests were repeated on teeth originating from young subjects. The resin adhesive was Prime & Bond NT (Caulk/Dentsply), while the resin-modified glass ionomer adhesive was Fuji Bond LC (GC America). Both were paired with the same hybrid resin composite, TPH3 (Caulk/Dentsply). Testing was performed after 48 hours using a "non-trimming" microtensile test at a crosshead speed of 0.6 mm/minute. No significant differences were observed between the young and aged teeth for any comparison (p > 0.05). SEM evaluation of the etched dentinal surfaces demonstrated less depth of decalcification in the intertubular areas of aged dentin, but there was no observable difference within the tubules of young and aged dentin.
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http://dx.doi.org/10.2341/07-80DOI Listing
July 2008

Microtensile dentin and enamel bond strengths of recent self-etching resins.

Oper Dent 2008 Jan-Feb;33(1):89-95

Department of Oral Rehabilitation, School of Dentistry, Medical College of Georgia, Augusta, GA, USA.

In this study, the microtensile bond strengths of resin composites to dentin and enamel produced by recently introduced self-etching resins were determined. Included were two adhesives with self-etching primers, Clearfil SE (Kuraray) and Peak SE (Ultradent), four self-etching adhesives, Optibond All-In-One (Kerr), Clearfil S3 (Kuraray), Adper Prompt L-Pop (3M ESPE) and iBond (Heraeus Kulzer) and, as a positive control, PQ1 (Ultradent), an etch-and-rinse adhesive. Each product was evaluated using the same hybrid resin composite, Z250 (3M ESPE). Testing was performed after 48 hours using a "non-trimming" microtensile test at a crosshead speed of 0.6 mm/minute. Sample size was five teeth per group, with the value for each tooth calculated by averaging the bond strengths of seven beams derived from it. Mean values in MPa (SD) for dentin were: Clearfil SE 81.6 (3.5),a Peak SE 80.3 (9.9),a PQ1 73.4 (4.9),a,b Optibond All-In-One 64.4 (5.9),b Clearfil S3 62.5 (2.2),b,c iBond 51.0 (4.0)c and Prompt L-Pop 33.9 (6.4).d Mean values in MPa (SD) for enamel were: PQ1 55.6 (2.5),a Clearfil SE 54.1 (5.4),a Prompt L-Pop 54.0 (5.4),a Peak SE 51.8 (1.5),a,b Clearfil S3 44.3 (5.2),b,c Optibond All-In-One 40.1 (2.1)c,d and iBond 33.8 (3.3).d (Values for each substrate with the same letter were not significantly different, one-way ANOVA, Tukey-Kramer Multiple Comparison Test, p<0.05.) Compared to the positive control, PQ1, only adhesives with self-etching primers, Clearfil SE and Peak SE, were as effective in bonding to both enamel and dentin. With the exception of Prompt L-Pop, scanning electron micrographs of the etched enamel surface produced by self-etching products indicated far less surface topography than conventional etching, even for self-etching primer systems producing the same bond strengths as the etch-and-rinse adhesive.
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http://dx.doi.org/10.2341/07-43DOI Listing
April 2008

The effect of light curing source on the residual yellowing of resin composites.

Oper Dent 2007 Sep-Oct;32(5):443-50

Department of Oral Rehabilitation, School of Dentistry, Medical College of Georgia, Augusta, GA, USA.

Purpose: This study evaluated the amount of residual yellow in cured resin composites when polymerizing with either a quartz-tungsten-halogen (QTH) or blue light-emitting diode (LED).

Material And Methods: Twelve shades (bleaching to conventional shades) of microfill, hybrid and microhybrid resin composite specimens (n = 10) were polymerized with both light types. All the materials contained only camphorquinone as the photoinitiator. After exposure, the specimens were stored in the dark for 24 hours. Then, the specimen color parameters were recorded (L*, a*, b* and C*(ab)) and color differences (deltaE*(ab)) were determined by examining for changes among the test combinations. Group comparisons were examined using ANOVA and the Tukey-Kramer post-hoc test, and pairwise comparisons were made using the Student's t-tests at a pre-set alpha of 0.05.

Results: When a significant difference in the shade of yellow was noted, the QTH light produced a greater yellow tinge than most comparisons using the LED. The potential for producing more residual yellowing could not be anticipated with respect to composite filler classification or shade, as this effect may be more dependent on individual product composition. The extent to which residual yellowing differences were noted between light curing units fell within levels considered detectable by the human eye (deltaE > 2.0).

Conclusion: The selection of light curing unit to polymerize resin-based restorative materials can have a significant influence on the amount of residual yellow present, with the QTH light tending to leave more yellow than an LED unit.
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http://dx.doi.org/10.2341/06-129DOI Listing
November 2007

Effect of restoration size on the clinical performance of posterior "packable" resin composites over 18 months.

Oper Dent 2007 May-Jun;32(3):212-6

Department of Oral Rehabilitation, School of Dentistry, Medical College of Georgia, Augusta, GA, USA.

Fifty predominantly moderate or large Class II or multiple-surface Class I resin composite restorations were placed in molars under rubber dam isolation. The restorative systems used were: Alert Condensable (Jeneric/Pentron) and SureFil (Dentsply/Caulk). The restorations were classified according to size, with 7 small, 25 moderate and 18 large, of which 8 were cusp replacement restorations. Baseline, 6, 12 and 18-month double-blinded clinical evaluations were carried out using modified USPHS criteria. The independent variables: restorative material, restoration size and three other clinical factors, were tested using a Multiple Logistic Regression procedure to determine if any were predictive of failure. Of the 50 restorations, four failed by the 18-month recall, three failed due to fracture of the restoration and one due to secondary caries. Both restorative systems demonstrated a 92% success rate. No association between restoration size (p = 0.99) or restorative material (p = 0.65) and failure was found. Similarly, the additional variables, occlusal contact type, presence of occlusal wear facets and first or second molar, were not predictive of failure.
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http://dx.doi.org/10.2341/06-87DOI Listing
June 2007

The importance of enamel adhesion.

Pract Proced Aesthet Dent 2007 Mar;19(2):78

Department of Oral Rehabilitation, School of Dentistry, Medical College of Georgia, Augusta, GA, USA.

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March 2007

The effect of chlorhexidine on dentin hybrid layers in vivo.

Oper Dent 2007 Mar-Apr;32(2):107-11

Department of Oral Rehabilitation, School of Dentistry, Medical College of Georgia, Augusta, GA 30912, USA.

This in vivo study evaluated by TEM the degradation of dentin hybrid layers in deep occlusal resin composite restorations. Caries-free premolars scheduled for extraction as part of orthodontic treatment were prepared, restored and evaluated after two and six months. The adhesive used was a single-bottle etch-and-rinse product (Single Bond Plus, 3M ESPE). Control group restorations were placed according to the manufacturer's instructions, while the experimental group received application of a 2% solution of chlorhexidine digluconate after etching. No degradation was observed in either group after two months. Slight degradation was found in the control group after six months, but none was observed in the experimental group. In vitro testing showed no significant difference in microtensile bond strength between the control and experimental adhesive protocols.
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http://dx.doi.org/10.2341/06-55DOI Listing
June 2007

Sealing properties of mineral trioxide aggregate orthograde apical plugs and root fillings in an in vitro apexification model.

J Endod 2007 Mar 4;33(3):272-5. Epub 2007 Jan 4.

School of Dentistry, Medical College of Georgia, Augusta, Georgia 30912-1129, USA.

One-visit mineral trioxide aggregate (MTA) apexification is gaining in popularity over the use of calcium hydroxide barriers. This study examined the sealing properties of two MTA apexification procedures using an in vitro apexification model. White MTA was introduced into instrumented single-rooted canals with standardized artificially created open apices to form 3- to 5-mm-thick orthograde apical plugs or complete orthograde fillings of the root segments. The remaining canal spaces in the former group were backfilled with thermoplasticized gutta-percha without a sealer. A Flodec fluid filtration device was used to record fluid flow across filled root canals at 48 hours and after 4 weeks of immersion in phosphate-buffered saline (PBS). Although MTA root fillings exhibited a better seal than MTA apical plugs at 48 hours, seals of these two groups were not significantly different after 4 weeks. Interaction of MTA with PBS may result in apatite deposition that improves the seal of MTA apical plugs with time.
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http://dx.doi.org/10.1016/j.joen.2006.11.002DOI Listing
March 2007

The microtensile bond strength of self-etching adhesives to ground enamel.

Oper Dent 2006 May-Jun;31(3):332-7

Department of Oral Rehabilitation, School of Dentistry, Medical College of Georgia, Augusta, GA, USA.

It is uncertain whether single-phase self-etching adhesives form bonds to enamel as reliable as those of etch-and-rinse adhesives. This study compared the microtensile bond strengths to ground enamel of three self-etching adhesive systems, a self-etching primer system and an etchand-rinse adhesive system. Human enamel was ground flat with 320-grit silicone carbide paper. The self-etching adhesives iBond (Heraeus Kulzer), Prompt L-Pop (3M ESPE) and Xeno III (Caulk/Dentsply), the adhesive with a self-etching primer Clearfil SE Bond (Kuraray) and the etch-and-rinse adhesive Scotchbond Multipur-pose (3M/ESPE) were applied as directed, followed by a core of the same manufacturers' hybrid resin composite. A microtensile bond strength evaluation was performed after 48 hours of water storage, using untrimmed beams approximately 0.9 mm2 in cross-sectional area at a crosshead speed of 0.6 mm/minute. There were no pretest failures in any group, and failures were predominately adhesive or mixed. Adhesion to enamel of Clearfil SE was not significantly different from Scotchbond Multi-Purpose, while the three self-etching adhesive systems demonstrated significantly lower bond strengths (One-way ANOVA, Tukey-Kramer Multiple-Comparison Test, p < 0.00001).
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http://dx.doi.org/10.2341/05-38DOI Listing
August 2006

Restoration of proximal contact in direct class II resin composites.

Oper Dent 2006 Jan-Feb;31(1):155-6

Department of Oral Rehabilitation, School of Dentistry, Medical College of Georgia, Augusta, GA 30912-1260, USA.

Although this technique performed well in the case presented, it becomes more advantageous with larger restorations. This would be especially true for core build-up restorations of missing cusps, although such cusps must be restored prior to placement of separating rings. Clear plastic matrices are available and permit effective curing of resins, but the authors find the preset contours of these matrices not sufficiently adaptable to differing clinical situations and prefer metal matrices, even though these necessitate additional light curing after matrix removal.
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http://dx.doi.org/10.2341/04-198DOI Listing
May 2006

Microleakage of Class V resin composites placed using self-etching resins: effect of prior enamel etching.

Quintessence Int 2006 Feb;37(2):109-13

Department of Oral Rehabilitation, School of Dentistry, Medical College of Georgia, Augusta 30912-1260, USA.

Objective: The purpose of this study was to compare the seal along dentin and enamel margins produced by 3 self-etching resin bonding systems to that of an etch-and-rinse adhesive system. Potential improvement in adaptation along enamel margins through the experimental use of conventional enamel etching prior to application of the self-etching adhesives was also evaluated.

Method And Materials: Class V resin composite restorations were placed in prepared cavities in extracted third molars using 3 self-etching dentin adhesive systems: Adper Prompt L-Pop (3M Espe), iBond GI (Heraeus Kulzer), and Tyrian SPE (Bisco), and an etch-and rinse adhesive, Adper ScotchBond Multi-Purpose (3M Espe). A group of teeth also underwent conventional enamel etching prior to use of the self-etching products. The restored teeth were thermocycled, subjected to a dye challenge, and sectioned. The sections were scored using an ordinal leakage scale (n = 20). Ranked data were analyzed using a 2-way analysis of variance and Tukey multiple comparison.

Results: When used as directed, there were no significant differences along dentin margins for any of the adhesives, but Adper Prompt and iBond demonstrated significantly greater leakage than the etch-and-rinse product along enamel margins. The incidence of enamel margin leakage decreased significantly for the same 2 products when enamel etching preceded use of the resin. Enamel etching increased the leakage along dentin margins for all 3 self-etching products, but not significantly.

Conclusion: Considerable improvement of all classes of dentin-adhesive resin systems is still needed. Practitioners should await further clinical trials before adopting use of self-etching resins, especially for large occlusal restorations.
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February 2006

Microtensile dentin bond strength of self-etching resins: effect of a hydrophobic layer.

Oper Dent 2005 Nov-Dec;30(6):733-8

Department of Oral Rehabilitation, School of Dentistry, Medical College of Georgia, Augusta, USA.

In this study, the microtensile bond strength of resin composites to dentin was determined when hydrophilic self-etching resins were used with and without an additional layer of a more hydrophobic adhesive. Included were three single-step self-etching adhesives, Adper Prompt L-Pop (3M ESPE), iBond GI (Heraeus Kulzer, Inc) and Xeno III (Caulk/Dentsply), and as a negative control, UniFil Bond (GC America), a self-etching primer with a separate adhesive. Each product was evaluated using a hybrid resin composite from its respective manufacturer, and each was used as directed and then used with an added layer of a more hydrophobic resin from its respective manufacturer. Testing was performed after 72 hours using a "non-trimming" microtensile test at a crosshead speed of 0.6 mm/minute. When the products were used according to manufacturers' directions, iBond had a significantly higher bond strength to dentin than the other three products (p<0.001), which were not significantly different from each other. For the three self-etching adhesive systems, the addition of a layer of a more hydrophobic resin produced significantly higher bond strengths to dentin (p<0.001), while no significant effect was found for the self-etching primer (p=0.40). A significant interaction was found between the variables product and adhesive treatment. The TEM evaluation of Prompt L-Pop and iBond demonstrated reduced nanoleakage with the additional resin layer.
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February 2006

Effects of multiple coatings of two all-in-one adhesives on dentin bonding.

J Adhes Dent 2005 ;7(2):133-41

Department of Operative Dentistry and Endodontology, School of Dentistry, Health Sciences University of Hokkaido, Hokkaido, Japan.

Purpose: Simple changes to bonding technique can improve resin-dentin bond strengths. The objective of this study was to evaluate the effects of multiple coatings of two all-in-one adhesive resins on both microtensile bond strength (microTBS) and nanoleakage.

Materials And Methods: The mid-coronal occlusal dentin of extracted human molars was used. Two all-in-one adhesives--iBond (Heraeus Kulzer) and Xeno III (Caulk Dentsply)--were applied to 320-grit abraded dentin surfaces. In groups 1 and 3 during bonding, monomer application and solvent evaporation were done 1, 2, 3, 4 or 5 times on the dentin surface before light curing. In groups 2 and 4 after light curing the first layer, the adhesive was re-applied, the solvent evaporated, and the layer light cured. This was repeated from 2 to 5 times, followed by creation of composite buildups. After 24 h storage in 37 degrees C water, the teeth were sectioned perpendicular to the adhesive interface to produce multiple beams of composite-bonded dentin, approximately 0.9 mm2 in area. These were tested to failure in tension. Data were evaluated by three-way ANOVA (material vs coatings vs light curing) followed by multiple comparisons at alpha = 0.05. Additionally, nanoleakage of silver uptake and adhesive layer thickness were evaluated using transmission electron microscopy (TEM).

Results: The results indicated that bond strengths increased with the number of coatings (p < 0.0001) with both adhesives, up to 3 layers, especially if each layer was light cured. Nanoleakage of silver tended to decrease with each coat in both adhesive systems.

Conclusion: By simply applying more coats of adhesive, the strength and quality of dentin adhesion can be improved.
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September 2005

Conversion of one-step to two-step self-etch adhesives for improved efficacy and extended application.

Am J Dent 2005 Apr;18(2):126-34

Pediatric Dentistry & Orthodontics, University of Hong Kong, China.

Purpose: One-step self-etch adhesives have restricted use due to their acid-base incompatibility with autocured composites and their behavior as permeable membranes after polymerization. This study examined the feasibility of their conversion to two-step self-etch adhesives via the adjunctive use of a non-solvented, relatively hydrophobic resin coating.

Methods: iBond, Xeno III and Adper Prompt were used either in multiple coats, or in a single coat followed by the use of a layer of Scotchbond Multi-Purpose Plus bond resin for coupling to light- and auto-cured composites. Four types of experiments were performed. Bonded specimens were examined with TEM after immersion in an ammoniacal silver nitrate tracer. Fluid flow measurements of iBond were conducted using the two application protocols to compare the permeability of the bonded dentin with the original smear layer. Permeability of vital dentin bonded with both application protocols were compared for the transudation of dentin fluid across the bonded dentin. Microtensile bond strengths of dentin bonded with the two protocols were examined for their compatibility with an auto-cured composite.

Results: The results of the four experiments were complementary. iBond and Xeno III exhibited "apparent incompatibility" to auto-cured composites that resulted from their inherent permeability. This was confirmed by the presence of dentin fluid transudate on the adhesive surfaces when they were bonded to vital dentin. Conversely, Adper Prompt exhibited "true incompatibility" to auto-cured composites that was caused by adverse acid-base interaction, masking the inherent permeability of this adhesive. "True" and "apparent" incompatibility issues were eliminated upon their conversion to two-step self-etch adhesives.
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April 2005

Microleakage of Class V resin composite restorations placed with self-etching adhesives.

J Prosthet Dent 2004 Jan;91(1):42-5

Department of Oral Rehabilitation, School of Dentistry, Medical College of Georgia, Augusta 30912-1260, USA.

Statement Of Problem: Although they are widely available, there is insufficient information about the capability of self-etching adhesives in sealing the margins of resin composite restorations.

Purpose: The purpose of this study was to compare the in vitro microleakage of Class V resin composite restorations placed using a strong pH self-etching adhesive, an intermediate pH self-etching adhesive, and an adhesive with a separate etchant and primer.

Material And Methods: Class V resin composite restorations (n = 8) were placed in prepared cavities in extracted human third molars using 2 self-etching dentin adhesives, Prompt L-Pop (Strong pH) or One-Up Bond F (Intermediate pH), and an adhesive with a separate etchant and primer, ScotchBond Multi-Purpose. The restored teeth received 1000 thermal cycles between 5 degrees C and 55 degrees C water baths with a 1-minute dwell time and were subsequently subjected to a methylene blue dye challenge and sectioned. The sectioned specimens were scored as demonstrating none, slight, or severe leakage (n=16). Ranked data were analyzed using a 1-way analysis of variance at a 5% confidence level.

Results: The only leakage observed was along gingival margins, with an incidence of 31% for Prompt L-Pop and One-Up Bond F, and 50% for ScotchBond Multi-Purpose.

Conclusion: No significant differences in marginal leakage were found among the adhesives tested.
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http://dx.doi.org/10.1016/j.prosdent.2003.10.003DOI Listing
January 2004

Two-year clinical performance of Class V resin-modified glass-lonomer and resin composite restorations.

Oper Dent 2003 Sep-Oct;28(5):477-81

Facultad de Estomatología, Benémerita Universidad Autónoma de Puebla, Puebla, Mexico.

While a one-year report had been previously published, this study was undertaken to evaluate the clinical performance and appearance of a resin-modified glass ionomer and a resin composite over two years. Thirty-seven pairs of restorations of FujI II LC and Z 250/Single Bond were placed in caries-free cervical erosion/abfraction lesions without tooth preparation. Restorations were clinically evaluated at baseline, 6, 12, 18 and 24 months using modified Ryge/USPHS criteria. No statistically significant difference (p = 0.13) was observed in the overall performance of the materials. Retention was 96% for the resin-modified glass ionomer and 81% for the resin composite, with no additional restorations of either material lost after one year. As previously reported, retention of the Z 250 restorations at six months was below the minimum specified in the ADA Acceptance Program for Dentin and Enamel Adhesives. The resin composite restorations generally had a better appearance, with a 100% alpha rating in color match, versus 85% for the resin-modified glass ionomer.
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December 2003

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

Oper Dent 2003 May-Jun;28(3):303-6

University of Nebraska Medical Center, Lincoln, NE, USA.

Although resin composite restorations may undergo relatively extreme temperature changes in the oral cavity, little is known about the effects of temperature on their adhesion to tooth structure. This study evaluated the effect of temperature on shear bond strength to dentin of three commercial resin dentin adhesives through testing of matured specimens over the 20 degrees to 55 degrees C temperature range. A significant difference (p < 0.05) was observed between 20 degrees C and 55 degrees C for all the materials, and for one of the materials, a significant difference was also observed between 20 degrees C and 37 degrees C.
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April 2004