^{February 2014 Abstracts}

Effect of dentin conditioning on bond strength of fiber posts and dentin morphology: A review

 

Navid  Khalighinejad,  Atiyeh  Feiz, dds,  Reyhaneh  Faghihian  &  Edward  J.  Swift, Jr., dmd, ms

 

Abstract: Purpose: Post and core systems are commonly used to restore endodontically treated teeth. A durable bond between fiber posts and dentin contributes to the success of the restorative treatment. Different irrigants are used during post space preparation and various studies have investigated the effects of these chemical agents on bond strength and dentin morphology. Methods: The MEDLINE-PubMed, Cochrane, and SCOPUS databases were searched for appropriate papers addressing the effects of irrigants on bonding of fiber posts to dentin and on dentin morphology. Databases were searched from 2002 through 2012. The search was performed using a variety of keywords including fiber posts, bond strength, post space preparation, post space irrigation, and smear layer removal. Results: Using multiple key words and different strategies, 68 publications were initially screened. The abstracts of these 68 publications were scanned for relevance, and 50 full-text articles were selected and read in detail. Thirty publications which discussed the effect of various intracanal irrigants on bond strengths of fiber posts and dentin morphology were incorporated in this review. Following review of all relevant papers, it can be concluded that bond strengths of fiber posts to radicular dentin can be affected by the irrigants used and that various irrigants affect different types of resin cements differently. (Am J Dent 2014;27:3-6).

 

 

 

Mail: Dr. Edward J. Swift, Jr., Department of Operative Dentistry, UNC School of Dentistry, CB#7450, 433 Brauer Hall, Chapel Hill, NC 27599-7450, USA.  E-mail: swifte@email.unc.edu

 

 

Immediate post-application effect of professional prophylaxis with 8% arginine-calcium carbonate desensitizing paste on hypersensitive teeth. A practitioner-based clinical trial

 

Chung-Hung Chu, bds, ms, phd  &  Edward Chin Man Lo, bds, ms, phd

 

Abstract: Purpose: This practitioner-based clinical trial compared the pain reduction achieved by professional prophylaxis with 8% arginine calcium carbonate (CaCO₃) desensitizing paste versus 5% potassium nitrate (KNO₃) toothpaste on adult patients with tooth hypersensitivity. Methods: All dentists in Hong Kong were invited to join the study. Each participating dentist identified six adult patients with hypersensitive teeth after scaling in the clinic. For each patient, the most hypersensitive tooth was selected. Each hypersensitive tooth was isolated and tested with a blast of compressed cold air delivered from a three-in-one syringe. The patient was then asked to indicate a sensitivity score (SS) from 0 to 10. Three patients received professional prophylaxis with 8% arginine CaCO₃ desensitizing paste (Group 1), and the other three received prophylaxis with desensitizing toothpaste containing 5% KNO₃ and 1,450 ppm fluoride (Group 2). The teeth were tested for a second time with compressed cold air, and the patients were asked to report the SS again. A non-parametric test was used to analyze the results following a normality test of the SS. Results: A total of 303 patients were recruited by 65 participating dentists. The mean age of the patients was 40.1, and 59% were female. The median pre-treatment SS of Groups 1 and 2 were both 7, whereas the post-treatment SS were 3 and 4, respectively (P< 0.001). The median percentage reductions in sensitivity scores of Groups 1 and 2 were 57.14% and 38.75%, respectively (P< 0.001). (Am J Dent 2014;27:7-11).

 

 

Mail: Dr. C.H. Chu, Faculty of Dentistry, The University of Hong Kong, 3B61, Prince Philip Dental Hospital, 34 Hospital Road, Hong Kong SAR, China. E-mail: chchu@hku.hk

 

MicroCT-based comparison between fluorescence-aided caries excavation and conventional excavation

 

Guangyun Lai, dds,  Dalia Kaisarly, dds,  Xiaohui Xu, dds   &  Karl-Heinz Kunzelmann, dds, phd

 

Abstract: Purpose: To evaluate and compare the use of micro-computed tomography (microCT) to investigate the mineral concentration of the treated dentin surface after caries removal with fluorescence-aided caries excavation (FACE) and conventional excavation. Methods: 20 extracted human teeth with dentin caries were bisected through the lesion center into two halves which were distributed to a FACE and a conventional excavation group. Tungsten-carbide round burs were used for both groups. Each specimen was investigated with microCT after excavation. The obtained images of all the specimens were evaluated using Image J. Based on the grey values, the linear attenuation coefficients were calculated. Four resin-embedded solid hydroxyapatite phantoms with the gradually increased mineral concen-tration were used to obtain a calibration curve and equation. Finally, the mineral concentration values of the superficial dentin of each specimen after removal and sound dentin were calculated. The data were compared with the Student's t-test. Results: The statistical results showed that the linear attenuation coefficient (LAC) of the treated surface was significantly lower (P< 0.0001) in the FACE group with a mean value of 2.13 ± 0.33 cm^-1. The value of the conventional excavation group was 2.98 ± 0.19 cm^-1. The LAC of sound dentin was 3.89 ± 0.10 cm^-1. By using the calibration equation, the calculated mineral concentration of the superficial dentin after caries removal were 0.68 ± 0.14 g/cm³ in the FACE group and 1.05 ± 0.08 g/cm³ in the conventional excavation group. The mineral concentration of sound dentin was 1.44 ± 0.04 g/cm³. The mineral concentration of the superficial dentin after caries removal in the FACE group was about 47% of that of sound dentin, while the value in the conventional excavation group was approximately 73% of that of sound dentin. Under the conditions of this in vitro study, the results of the microCT evaluation may imply that FACE was more conservative than conventional excavation. (Am J Dent 2014;27:12-16).

 

 

 

 

 

Mail: Prof. Karl-Heinz Kunzelmann, Goethe Str. 70, D-80336 Munich, Germany. E-mail: karl-heinz@kunzelmann.de

 

 

Flexural resistance of Cerec CAD/CAM system ceramic blocks. Part 2: Outsourcing materials

 

Maurizio Sedda, dds,  Alessandro Vichi, dds, phd,  Francesco Del Siena, dds,  Chris Louca, bsc, bds, phd &  Marco Ferrari, md, dds, phd

 

Abstract: Purpose: To test different Cerec CAD/CAM system ceramic blocks, comparing mean flexural strength (σ), Weibull modulus (m), and Weibull characteristic strength (σ₀) in an ISO standardized set-up. Methods: Following the recent ISO Standard (ISO 6872:2008), 11 types of ceramic blocks were tested: IPS e.max CAD MO, IPS e.max CAD LT and IPS e.max CAD HT (lithium disilicate glass-ceramic); In-Ceram SPINELL, In-Ceram Alumina and In-Ceram Zirconia (glass-infiltrated materials); inCoris AL and In-Ceram AL (densely sintered alumina); In-Ceram YZ, IPS e.max Zir-CAD and inCoris ZI (densely sintered zirconia). Specimens were cut out from ceramic blocks, finished, crystallized/infiltrated/sintered, polished, and tested in a three-point bending test apparatus. Flexural strength, Weibull characteristic strength, and Weibull modulus were obtained. Results: A statistically significant difference was found (P< 0.001) among lithium disilicate glass-ceramic (σ = 272.6±376.8 MPa, m = 6.2±11.3, σ₀ = 294.0±394.1 MPa) and densely sintered alumina (σ = 441.8±541.6 MPa, m = 11.9±19.0, σ₀ = 454.2±565.2 MPa). No statistically significant difference was found (P= 0.254) in glass infiltrated materials (σ = 376.9±405.5 MPa, m = 7.5±11.5, σ₀ = 393.7±427.0 MPa). No statistically significant difference was found (P= 0.160) in densely sintered zirconia (σ = 1,060.8±1,227.8 MPa, m = 5.8±7.4, σ₀ = 1,002.4±1,171.0 MPa). Not all the materials tested fulfilled the requirements for the clinical indications recommended by the manufacturer. (Am J Dent 2014;27:17-22).

 

 

 

 

 

 

Mail: Dr. Alessandro Vichi, Via Derna 4, 58100 Grosseto, Italy. E-mail: alessandrovichi1@gmail.com

 

Role of fluoridated dentifrices in root caries formation in vitro

 

Franklin GarcÍa-Godoy, dds, ms, phd, phd,  Catherine  Flaitz, dds, ms  &  John Hicks, dds, ms, phd, md

 

Abstract: Purpose: To evaluate in vitro root caries formation in human permanent teeth and to determine the effects of commercially available dentifrices containing different amounts of fluoride, while employing a well-tested artificial caries system using an acidified gel. Methods: Root surfaces from caries-free human permanent teeth (n=10) underwent debridement and fluoride-free prophylaxis. The tooth roots were sectioned into six portions, and acid-resistant varnish was placed with two sound root surface windows exposed on each tooth portion. Each portion from a single tooth was assigned to a treatment group: (1) No treatment control; (2) Denticious 5000 dentifrice (5,000 ppm F + xylitol); (3) PreviDent 5000 (5,000 ppm F); (4) AIM dentifrice (1,500 ppm F); (5) Listerine dentifrice (1,300 ppm F); and (6) Crest Regular Paste (1,500 ppm F). Tooth portions were treated with fresh dentifrice twice daily for 180 seconds, followed by fresh synthetic saliva rinsing over a 7-day period. Controls were exposed twice daily to fresh synthetic saliva rinsing over a 7-day period. In vitro root caries were created using an acidified gel (pH 4.25, 21 days). Longitudinal sections (three sections/tooth portion, 30 sections/group; 60 lesions/group) were evaluated for mean lesion depths (water imbibition, polarized light). Statistical analyses were performed using ANOVA and Duncan’s Multiple Range test. Results: Mean lesion depths were 389 ± 43 μm for No treatment - control, 223 ± 33 μm for Denticious 5000 dentifrice, 242 ± 42 μm for Prevident 5000, 337 ± 29 μm for AIM dentifrice, 297 ± 37 μm for Listerine dentifrice, and 282 ± 34 μm for Crest Regular Paste dentifrice. All treatment groups had mean depths significantly less than the No treatment - control group (P< 0.05). Denticious 5000 and PreviDent 5000 had significantly reduced mean depth compared with the other dentifrice treatment groups (P< 0.05). (Am J Dent 2014;27:23-28).

 

 

Mail: Dr. Franklin Garcia-Godoy, Department of Bioscience Research, College of Dentistry, University of Tennessee Health Science Center, 875 Union Avenue, Memphis, TN 38163, USA.  E-mail:  fgarciagodoy@gmail.com

 

Effect of simulated intraoral erosion and/or abrasion effects on etch-and-rinse bonding to enamel

 

Linda Wang, dds, ms, phd, Leslie C. Casas-Apayco, dds, ms, phd, Ana Carolina HipÓlito, dds,

Vanessa Manzini Dreibi, dds, Marina Ciccone Giacomini, dds, Odair Bim JÚnior, dds, ms,

Daniela Rios, dds, ms, phd  &  Ana Carolina Magalhães, dds, ms, phd

 

Abstract: Purpose: To assess the influence of simulated oral erosive/abrasive challenges on the bond strength of an etch-and-rinse two-step bonding system to enamel using an in situ/ex vivo protocol. Methods: Bovine enamel blocks were prepared and randomly assigned to four groups: CONT - control (no challenge), ABR - 3x/day-1 minute toothbrushing; ERO - 3x/day - 5 minutes extraoral immersion into regular Coca Cola; and ERO+ABR - erosive protocol followed by a 1-minute toothbrushing. Eight blocks were placed into an acrylic palatal appliance for each volunteer (n=13), who wore the appliance for 5 days. Two blocks were subjected to each of the four challenges. Subsequently, all the blocks were washed with tap water and Adper Single Bond 2/ Filtek Z350 were placed. After 24 hours, 1 mm²-beams were obtained from each block to be tested with the microtensile bond strength test (50 N load at 0.5 mm/minute). The data were statistically analyzed by one-way RM-ANOVA and Tukey’s tests (α= 0.05). Results: No difference was detected among the ABR, ERO, and CONT groups (P> 0.05). ERO+ABR group yielded lower bond strengths than either the ABR and ERO groups (P< 0.0113). (Am J Dent 2014;27:29-34).

 

 

 

 

 

Mail: Prof. Dr. L. Wang, Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Al. Dr. Octávio Pinheiro Brisolla, n. 9-75, Vila Universitária, 17012-101 - Bauru, SP, Brazil.  E-mail:  wang.linda@usp.br/wang.linda@uol.com.br

 

In vitro detection of DNA damage in human leukocytes induced by combined effect of resin composites and adhesive systems

 

Danijela  Marovic, dmd, phd,  Antonija  Tadin,  dmd, msc, phd,  Marin  Mladinic, phd,

Danijela  Juric-Kacunic, dmd, msc  &  Nada Galic, dmd, msc, phd

 

Abstract: Purpose: To simultaneously evaluate the genotoxicity of dental composites and adhesive systems in vitro using a cytogenetic assay, with respect to the influence of composite shade. Methods: Genotoxicity assessment was carried out in human peripheral blood leukocytes using the comet assay. Three resin composite materials, two micro-hybrids and one nano-hybrid, in shade A1 and A3.5 were used with manufacturer-recommended four adhesive systems. Cultures were treated for 48 hours with samples after elusion for 1 hour, 1 day, 7 days or 30 days, in two different concentrations (4.16 mg/mL, 8.33 mg/mL). Kruskall-Wallis test was used for the statistical analysis (α=0.05). Results: For combinations of micro-hybrid composite (A3.5) with two self-etch adhesives (16.1 ± 5.50 and 16.2 ± 9.52) after exposure to samples eluted for 1 day, the incidence of primary DNA damage was significantly higher than for the corresponding negative control (14.7 ± 2.85). Genotoxicity was also higher after treatment with samples eluted for 1 hour (15.3 ± 4.70) and 1 day (15.3 ± 9.10), comprised of nano-hybrid composite (A1) with self-etch adhesive in relation to the control (13.1 ± 1.70). There was no clear trend of increased DNA damage in material combinations with darker shades of composites. Material composition and higher material concentrations showed greater influence on the genotoxicity. (Am J Dent 2014;27:35-41).

 

 

Mail: Dr. Antonija Tadin, Department of Endodontics and Restorative Dental Medicine, Study of Dental Medicine, School of Medicine, University of Split, Soltanska 2, 21000 Split, Croatia.  E-mail: atadin@mefst.hr

 

 

Laboratory evaluation of the effect of toothbrushing on surface gloss of resin composites

 

Dorien  Lefever, msc, dmd,  Ivo  Krejci,  dmd, phd  &  Stefano  Ardu, phd

 

Abstract: Purpose: To determine changes in surface gloss of different composite materials after laboratory toothbrushing simulation. Methods: 40 specimens were fabricated for each material (Filtek Supreme XTE, Renamel, Empress Direct, Gradia Direct, Edelweiss, G-aenial, Venus Pearl and Venus Diamond) and polished with 120-, 220-, 500-, 1200-, 2400- and 4000- grit SiC abrasive paper, respectively. Gloss measurements were made with a glossmeter prior to testing procedures and then subjected to simulated toothbrushing for 5, 15, 30 and 60 minutes by means of an electrical toothbrush with a pressure of 2N while being immersed in a 50 RDA toothpaste slurry. Four samples per group were analyzed under SEM immediately after polishing procedures and four samples after 60 minutes simulated toothbrushing in order to evaluate the causes of the gloss decrease. Human enamel was the control group. Statistical analysis was performed using Kruskal Wallis and Tukey’s post-hoc test (P< 0.05). Results: Resin composite initial gloss values ranged from 78.2 to 100.5 at baseline to 13.8 to 62.4 after 1 hour of brushing. Highest gloss values were obtained by Filtek Supreme XTE and Renamel (P< 0.05), followed by Empress Direct. Lowest values were obtained with Venus Diamond, Venus Pearl, G-aenial and Edelweiss. Human enamel was the only material which maintained its gloss throughout the brushing procedure (110.4 after 60 minutes). SEM analysis revealed different patterns of surface degradation dependant on the material. (Am J Dent 2014;27:42-46).

 

 

 

 

Mail: Dr. Dorien Lefever, Division of Cariology and Endodontics, University of Geneva, 19, Rue Barthélémy MENN, 1205 Geneva, Switzerland. E-mail: Dorien.Lefever@unige.ch

 

 

Efficacy of hydrogen-peroxide-based mouthwash in altering enamel color

 

Ivone  Maria De Lima  Jaime, dds, ms,   Fabiana  Mantovani  Gomes  FranÇa, dds, ms, phd,

Roberta  Tarkany  Basting, dds, ms, phd,   Cecilia  Pedroso  Turssi, dds, ms, phd

&  FlÁvia  Lucisano  Botelho  Amaral, dds, ms, phd

 

Abstract: Purpose: To analyze the efficacy of Colgate Plax Whitening mouthwash containing 1.5% hydrogen peroxide. Methods: 30 enamel fragments, obtained from the proximal surfaces of human third molars were darkened with Orange II methyl orange. The fragments were divided into three groups according to the type of bleaching agent applied (n = 10): (1) 10% carbamide peroxide gel (positive control, PC) was applied for 2 hours/day for 28 days; (2) a solution containing 1.5% hydrogen peroxide (Plax) was applied for 4 minutes once a day for 28 days, and (3) no bleaching agent, kept in artificial saliva (negative control, AS). The specimens were kept in artificial saliva between treatment intervals. The specimens were photographed before darkening (baseline), after darkening and before lightening and on the 28^th day of whitening. Afterwards, they were analyzed with color measurement software using the CIELab system. The data for the L*, a* and b* parameters were submitted to two-way ANOVA with repeated measures. The values of ∆L *, ∆a *, ∆b * and ∆E* were calculated using two procedures: (1) darkened versus original, and (2) bleached versus darkened. This data was submitted to the one-way ANOVA test. Multiple comparisons were conducted using the Tukey test (α=0.05). Results: When the specimens were subjected to bleaching agents, there was a significant increase in the brightness (L* parameter) of the enamel exposed to the gel and also to the bleaching solution. However, higher brightness was observed for the PC (gel) group. As for the axis a* parameters, there were no significant differences between the bleaching products. Regarding the axis b* parameters, the PC group underwent major changes (indicating a color change toward blue chroma), statistically greater than those of the Plax group. After bleaching, there was a significantly greater color change (∆E*) in the PC group. Although the Plax solution caused a color change, it was less than that produced by the gel. The slightest color change was observed in the control group, in which no bleach was used. The mouthwash containing hydrogen peroxide was able to lighten the darkened human enamel, but to a lesser degree than the lightening produced by 10% carbamide peroxide. (Am J Dent 2014;27:47-50).

 

 

 

 

Mail: Prof. Dr. Flávia Lucisano Botelho Amaral, São Leopoldo Mandic Institute and Research Center, Rua José Rocha Junqueira, 13, Ponte Preta, Campinas-SP CEP: 13045-755, Brazil.  E-mail: flbamaral@gmail.com

 

 

Resistance against bacterial leakage of four luting agents used for cementation of complete cast crowns

 

Osvaldo Zmener, dds, dr. odont,  Cornelis H. Pameijer, dmd, mscd, dsc, phd  &  Sandra HernÁndez, dds

 

 

Abstract: Purpose: To assess the sealing properties of four luting materials used for cementation of full cast crowns. Methods: 40 human premolars were prepared with a chamfer finish line. Stone dies were fabricated and copings were waxed, invested and cast in gold. Ten samples (n=10) were randomly assigned to four groups. In two groups, resin modified glass-ionomer cements were used, ACTIVA BioACTIVE-CEMENT/BASE/LINER and FujiCem2; the third group received the self-adhesive resin cement Embrace WetBond, while the fourth group served as control with a zinc phosphate cement. After cementation, excess cement was removed followed by bench-set for 10 minutes. All samples were stored in water at 37°C and subjected to thermal cycling (×2000 between 5 and 55°C). Subsequently the occlusal surface was reduced exposing the dentin. After sterilization the specimens were subjected to bacterial microleakage with E. faecalis in a dual chamber apparatus for a period of 60 days. Bacterial leakage was checked daily. Data were analyzed using the Kaplan-Meyer survival test. Significant pairwise differences were analyzed using the Log Rank test and the Fishers’ exact test at P< 0.05. Results: ACTIVA BioACTIVE-CEMENT/BASE/LINER, FujiCem2 and Embrace WetBond showed the lowest microleakage scores and differed statistically significantly (P< 0.05) from zinc phosphate cement. (Am J Dent 2014;27:51-55).

 

 

 

 

 

 

 

Mail: Dr. Cornelis H. Pameijer, 10 Highwood, Simsbury CT 06070, USA. E-mail: cornelis@pameijer.com

 

A 4-week clinical comparison of an oscillating-rotating power brush versus a marketed sonic brush in reducing dental plaque

 

Barbara BÜchel, Markus Reise, dmd, Malgorzata Klukowska, dds, phd, Julie Grender, phd, Hans Timm, phd, Renzo Alberto Ccahuana-Vasquez, dds, phd  &  Bernd W. Sigusch, dmd, dds

 

Abstract: Purpose: To assess the plaque removal efficacy of an oscillating-rotating power brush relative to a newly-introduced sonic power brush. Methods: This study used a randomized, examiner-blind, single-center, two-treatment, parallel group 4-week design. Subjects with pre-existing plaque scores of at least 1.75 on the Turesky Modification of the Quigley-Hein Plaque Index (TMQHPI) were evaluated for baseline whole mouth and approximal plaque scores. They received either the oscillating-rotating brush (Oral-B Professional Care 1000, sold as Oral-B Professional Care 600 in some regions, with the Oral-B Precision Clean brush head, D16u/EB20) or the sonic brush (Colgate ProClinical C200 with Colgate Triple Clean brush head) and brushed twice-daily with the assigned brush and a standard fluoride dentifrice for 4 weeks before returning for plaque measurements. Prior to baseline and the Week 4 measurements, par­ticipants abstained from oral hygiene for 12 hours and from eating, chewing gum and drinking for 4 hours. Results: A total of 131 subjects were enrolled in the study at baseline, with all completing the study: 65 in the oscillating-rotating group, and 66 in the sonic group. Both brushes significantly reduced plaque over the 4-week study period. The oscillat­ing-rotating brush was statistically significantly more effective in reducing plaque (P< 0.001) than the sonic brush. Compared to the sonic power brush, the adjusted mean plaque reduction scores for the oscillating-rotating power brush were more than five times greater for whole mouth and approximal areas. (Am J Dent 2014;27:56-60).

 

 

 

 

 

Mail: Dr. Malgorzata Klukowska, Procter & Gamble Health Care Research Center, 8700 Mason-Montgomery Road, Mason, OH 45040, USA. E-mail: klukowska.m@pg.com