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February 2010


Research Article

Effect of cigarette smoke and whiskey on the color stability of dental composites


Mariana  de  Souza  AraÚjo  Wasilewski, dds, mds,  Marcos  Kenzo  Takahashi, dds, mds, phd,

Giovanna  Andraus  Kirsten, dds, mds  &  Evelise  Machado  de  Souza, dds, mds, phd


Abstract: Purpose: To evaluate the effect of cigarette smoke and whiskey on the color stability of resin composites. Methods: Disk-shaped specimens (8 mm x 1 mm) were prepared with five composites in two different shades (n=10). After light-curing, the specimens were stored in dark containers with artificial saliva at 37ºC for 24 hours. Baseline color was measured by CIEL*a*b* using a colorimeter (Easy-Shade, VITA). Half of the specimens were subjected to a discoloration process in a cigarette smoking machine (SM) and the other half to an immersion in whiskey (WH) for 24 hours. Another color measurement was performed for discolored specimens. The samples subjected to smoking were immersed in whiskey (SM/WH) and those subjected to whiskey immersion were subjected to cigarette smoking (WH/SM) followed by another color measurement. Color changes (∆E*) were calculated and submitted to repeated measures 4-way ANOVA and Tukey tests (P< 0.05). Results: The most significant color change was observed after WH/SM (∆E*= 22.8-31.5) discoloration process, followed by SM (∆E*= 7.0-18.0), SM/WH (∆E*= 4.9-16.5) and WH (∆E*= 2.0 to 9.5). Translucent shades were more susceptible to discoloration than enamel shades. All the groups, with the exception of two, showed a significantly high perceptible color change (∆E*> 3.3). Based on the results, the color stability of dental composites was affected by the discoloration process and was material and shade dependent. (Am J Dent 2010;23:4-8).


Clinical significance: Resin composites are susceptible to discoloration by oral habits such as cigarette smoking and alcoholic beverage drinking. This in vitro study suggested that the association of both habits can exacerbate the color changes of composites, mainly when translucent shades are used.


Address: Dr. Evelise Machado de Souza, School of Dentistry, Post-graduate Program, Pontifical Catholic University of Parana, R. Imaculada Conçeicão, 1155, Prado Velho Curitiba, PR, 80215-901, Brazil .  E-mail:




Research Article

Prevalence and severity of gingivitis in American adults


Yiming  Li, dds, msd, phd,  Sean  Lee, dds, Philippe  Hujoel, dmd, phd,  Mingfang  Su, dds, ms,  Wu  Zhang, md, Jay  Kim, phd,  Yun  Po  Zhang, ms, phd  &  William  DeVizio, dmd


Abstract: Purpose: To investigate prevalence and severity of gingivitis in representative American adults. Methods: Subjects (1,000) in Loma Linda, California; Seattle, Washington; and Boston, Massachusetts were examined for Löe-Silness Gingivitis Index (GI). Mann-Whitney rank sum test was used to determine significances in the GI between genders. The data among study sites and races were compared using the Kruskal-Wallis one-way ANOVA on ranks. The correlation of the GI and age was examined by the Spearman rank order correlation. Age differences among three sites were analyzed using the one-way ANOVA. Results: The race composition of the subjects (mean age 37.9) approximated to the 2004 U.S. Census data. The overall average GI was 1.055. Only 6.1% of subjects showed mean GI <0.50; most (93.9%) were ≥ 0.50, with 55.7% ≥ 1.00. There was a significant correlation (P< 0.001) between the age and GI. The males’ GI was significantly higher (P< 0.001) than the females’; African-Americans showed a significantly higher GI (P< 0.05) than other races except for the Native-Americans. (Am J Dent 2010;23:9-13).


Clinical significance: The average GI in adults recruited in three cities is slightly ≥1.0; age, gender, race and subject source can influence the prevalence and severity of gingivitis. For gingivitis studies, proper subject source, age, gender and race compositions need to be considered for recruiting a representative study population.


Address: Dr. Yiming Li, Center for Dental Research, Loma Linda University School of Dentistry, 24876 Taylor Street, Loma Linda, CA  92350, USA. E-mail:



Research Article

The effect of curing mode on extent of polymerization and microhardness of dual-cured, self-adhesive resin cements


Milena  Cadenaro, dds, phd, Chiara  Ottavia  Navarra, dds, phd,  Francesca  Antoniolli, eng, phd,  

Annalisa Mazzoni, dds, phd,  Roberto  Di  Lenarda, dds,  Frederick  Allen  Rueggeberg, dmd, ms 

&  Lorenzo  Breschi, dds, phd


Abstract: Purpose: To compare the effect of curing mode (self- or light-cure) on the extent of polymerization (%EPl as measured using differential scanning calorimetry, (DSC) and microhardness of two dual-cured, self-adhesive resin cements, using a conventional, dual-cured resin cement as control. Methods: Small amounts of the commercial self-adhesive cements Maxcem and RelyX Unicem or Panavia F2.0 dual-cure resin based cement used as control were polymerized within the DSC chamber at 35°C under a nitrogen atmosphere. 10 specimens were light-cured immediately (20 seconds, 600 mW/cm2) and left undisturbed for 2 hours and 10 additional specimens were left to self-cure in the dark for 2 hours. Following DSC treatment, microhardness of the specimens was measured (Vickers). For each test parameter, data were analyzed with a two-way ANOVA and the Tukey post hoc test. Results: %EP and microhardness of all cements were higher when the light-cure mode of dual-activation was used (P< 0.05) instead of only self-curing. No significant difference in %EP was found between either self-adhesive cement or the control using either the light- or self-curing modes. In the light-activated mode, the conventional, dual-cure control cement demonstrated lower microhardness than the self-adhesive cements (P< 0.05). (Am J Dent 2010;23:14-18).


Clinical significance: Dual-cured, self adhesive resin cements showed an extent of polymerization comparable to the conventional, dual-cured resin cement tested.


Address: Prof. Lorenzo Breschi, Department of Biomedicine, Unit of Dental Sciences and Biomaterials, University of Trieste, Piazza Ospedale 1, I-34129 Trieste, Italy.  E-mail:



Research Article

Effect of hydrogen peroxide on microhardness and color change of resin nanocomposites


Yong  Hoon  Kwon, phd,  Dong-Hee  Shin, dds, ms,  Dong-In  Yun, dds, ms,  Young-Joon  Heo, dds,

Hyo-Joung  Seol, phd  &  Hyung-Il  Kim, dds, phd


Abstract: Purpose: To examine the effect of hydrogen peroxide on the microhardness and color change of resin composites containing nanofillers. Methods: Three resin nanocomposites with three different shades and two different tooth whitening agents were used. The specimens were given a 3-week treatment with one of three protocols: (1) 7 hours/day treatment of carbamide peroxide (CP) + 17 hours/day immersion in distilled water (DW); (2) 1 hour/week treatment of hydrogen peroxide (HP) + immersion in DW for the rest of the week; and (3) immersion in DW for 24 hours/day. The microhardness and color changes were measured after treatment. Results: After treatment with the whitening agents, there was an 8.1~10.7% decrease in the original microhardness. These values were similar to those obtained from the samples treated with distilled water. In the same resin product, the decrease was similar regardless of the test agents used. In most cases, the color change was only slight (ΔE*=0.5~1.4). Hydrogen peroxide enhanced the color change but the absolute color change values were similar in the same product and shade, regardless of the test agent used. (Am J Dent 2010;23:19-22).


Clinical significance: Within the limits of this study, carbamide peroxide and hydrogen peroxide had no additional effect on the microhardness and color change of resin nanocomposites compared with the samples treated with distilled water.


Address: Prof. Yong Hoon Kwon, Department of Dental Materials, School of Dentistry, Pusan National University, Yangsan 626-870,  Korea.  E-mail:



Research Article

Microtensile bond strength of etch-and-rinse and self-etch adhesive systems to demineralized dentin after the use of a papain-based chemomechanical method


Renato JosÈ Gianini, dds,  FlÁvia Lucisano Botelho do Amaral, dds, ms,  FlÁvia MartÃo FlÓrio,  dds, ms, scd &  Roberta Tarkany Basting, dds, ms, phd


Abstract: Purpose: To evaluate the in vitro microtensile bond strength (µTBS) of etch-and-rinse and self-etch adhesive systems to demineralized dentin after the use of a papain-based chemomechanical method. Methods: 36 demineralized human dentin slabs were randomly distributed into two groups according to the method of caries removal: (1). Mechanical removal with manual excavators; (2) Chemomechanical removal with a papain-based gel (Papacárie). Subsequently, three adhesive systems were applied (n=6): (a) an etch-and-rinse adhesive system (Single Bond); (b) a two-step self-etch adhesive system (AdheSE); (c) a one-step self-etch adhesive system (Adper Prompt). The slabs were restored with a microhybrid resin composite and each resin-dentin block was sectioned into 1.0 mm2 thick slabs, which were kept in receptacles containing distilled water at relative humidity, for 24 hours, at 37°C. After that, they were subjected to tensile stress in a universal testing machine at a speed of 0.5 mm/minute. Data were submitted to two-way ANOVA and Tukey’s test at a 0.05 level of significance. The fractured specimens were observed under a stereomicroscope to assess the failure mode. Results: The application of both chemomechanical and mechanical methods on demineralized dentin yielded µTBS values that were statistically similar among them, regardless of the adhesive system used. Caries removal with a chemomechanical papain-based method did not interfere in the adhesion of the tested adhesive systems to demineralized dentin. (Am J Dent 2010;23:23-28).


Clinical significance: The use of a papain-based chemomechanical method for caries removal did not affect the adhesion of etch-and-rinse and self-etch adhesives to demineralized dentin.


Address: Prof. Dr. Roberta Tarkany Basting, Faculty of Dentistry and Center for Dental Research São Leopoldo Mandic, Department of Restorative Dentistry - Operative, Rua José Rocha Junqueira, 13 Bairro Swift, Campinas, SP, CEP: 13045-755, Brazil.  E-mail:



Research Article

Effect of long-term water aging on microtensile bond strength of self-etch adhesives to dentin


Ali  I.  Abdalla, phd


Abstract: Purpose: To evaluate the effect of water storage on the microtensile dentin bond strength of one total-etch and four self-etching adhesives to dentin. Methods: The adhesive materials were: one total-etch adhesive (Admira Bond) and four self-etch adhesives (Clearfil S tri Bond, Hybrid Bond, Futurabond NR, Adhe SE). Freshly extracted human third molar teeth were used. For each tooth, dentin was exposed on the occlusal surface by cutting with an Isomet saw and the remaining part was mounted in a plastic ring using dental stone. After adhesive application, a composite resin (Grandio) was placed in 5-6 mm height to form a crown segment. For each tested adhesive, two test procedures (n=6 teeth) were carried out. Procedure A: the teeth were stored in water for 24 hours, and then sectioned longitudinally, buccolingually and mesiodistally to get rectangular beams of 1 ± 0.1 mm thickness on which a micro-tensile test was carried out. Procedure B: The specimens were stored in water at 37°C for 3 years before sectioning and microtensile testing. During microtensile testing the beams were placed in a universal testing machine and load was applied at cross-head speed of 0.5 mm/minute. Results: For the 24-hour water storage groups, there was no significant difference in the bond strength between the different adhesives. After 3 years of water storage, the bond strength of all self-etch adhesives was significantly reduced compared to the control groups (24 hours). In contrast, the bond strength of Admira Bond was not significantly reduced. (Am J Dent 2010;23:29-33).


Clinical significance: Water storage for 3 years significantly reduced the bond strength of tested self-etch adhesives to dentin. The bond produced by the total-etch system was able to resist 3-year water degradation.


Address: Dr. Ali I. Abdalla, Department of Restorative Dentistry, Faculty of Dentistry, University of Tanta, Tanta, Egypt. E-mail:



Research Article

Indirect pulp treatment in primary teeth: 4-year results


Luciano  Casagrande, dds,ms, phd, LetÍcia  Westphalen  Bento, dds, ms,  DÉbora  Martini  Dalpian,dds, ms Franklin  GarcÍa-Godoy, dds, ms  &  Fernando  Borba  de  Araujo, dds, ms, phd


Abstract: Purpose: To evaluate clinical and radiographic outcomes of indirect pulp treatment (IPT) in primary molars after long-term function (up to 60 months). Methods: Teeth with deep carious lesions without signs and symptoms of irreversible pulpitis were divided by random allocation into two groups, according to the capping material utilized over demineralized dentin: experimental group (1): self-etching adhesive system (Clearfil SE Bond); and control group (2): calcium hydroxide liner (Dycal). Both groups were filled with resin composite (Z250) and submitted to a clinical and radiographic monitoring period until exfoliation. Results: After the follow-up period (up to 60 months), no statistical difference was found between groups (P= 0.514). The overall success rate reached 78%. The failures occurred after the first year period recall. (Am J Dent 2010;23:34-38).


Clinical significance: The IPT provides an alternative treatment of primary teeth with deep carious lesions representing a simple and effective technique to maintain the pulp vitality.


Address: Dr. Luciano Casagrande, School of Dentistry, Franciscan University Center (UNIFRA), Andradas 1614, Santa Maria, RS  97010 032, Brazil.  E-mail:



Research Article

Effect of staining solutions on discoloration of resin nanocomposites


Jeong-Kil  Park, dds, phd,  Tae-Hyong Kim, dds, ms,  Ching-Chang  Ko, dds, phd,  Franklin  García-Godoy, dds, ms, Hyung-Il  Kim, dds, phd  &  Yong  Hoon  Kwon, phd


Abstract: Purpose: To examine the effect of staining solutions on the discoloration of resin nanocomposites. Methods: Three resin nanocomposites (Ceram X, Grandio, and Filtek Z350) were light cured for 40 seconds at a light intensity of 1000 mW/cm2. The color of the specimens was measured in %R (reflectance) mode before and after immersing the specimens in four different test solutions [distilled water (DW), coffee (CF), 50% ethanol (50ET) and brewed green tea (GT)] for 7 hours/day over a 3-week period. The color difference (ΔE*) was obtained based on the CIEL*a*b* color coordinate values. Results: The specimens immersed in DW, 50ET and GT showed a slight increase in L* value. However, the samples immersed in CF showed a decrease in the L* value and an increase in the b* value. CF induced a significant color change (ΔE*: 3.1~5.6) in most specimens but the other solutions induced only a slight color change. Overall, coffee caused unacceptable color changes to the resin nanocomposites. (Am J Dent 2010;23:39-42).


Clinical significance: Within the limits of this study, coffee can induce an unacceptable color change in resin nanocomposites if used regularly for a long time.


Address: Prof. Yong Hoon Kwon, Department of Dental Materials, School of Dentistry, Pusan National University, Yangsan 626-870, Korea.  E-mail:



Research Article

Push-out strength of modified Portland cements and resins


Francesco Iacono, dds, ms,  Maria Giovanna Gandolfi, mbiol, dsc, mbio, phd,  Bradford Huffman, bs,  Jeremy Sword, bs,  Kelli Agee, bs,  Francesco Siboni, dds,   Franklin Tay, bdsc (hons), phd,

Carlo Prati, md, dds, phd  &  David Pashley, dmd, phd



Abstract: Purpose: Modified calcium-silicate cements derived from white Portland cement (PC) were formulated to test their push-out strength from radicular dentin after immersion for 1 month. Methods: Slabs obtained from 42 single-rooted extracted teeth were prepared with 0.6 mm diameter holes, then enlarged with rotary instruments. After immersion in EDTA and NaOCl, the holes were filled with modified PCs or ProRoot MTA, Vitrebond and Clearfil SE. Different concentrations of phyllosilicate (montmorillonite-MMT) were added to experimental cements. ProRoot MTA was also included as reference material. Vitrebond and Clearfil SE were included as controls. Each group was tested after 1 month of immersion in water or PBS. A thin-slice push-out test on a universal testing machine served to test the push-out strength of materials. Results were statistically analyzed using the least squares means (LSM) method. Results: The modified PCs had push-out strengths of 3-9.5 MPa after 1 month of immersion in water, while ProRoot MTA had 4.8 MPa. The push-out strength of PC fell after incubation in PBS for 1 month, while the push-out strength of ProRoot MTA increased. There were no significant changes in Clearfil SE Bond or Vitrebond after water or PBS storage. (Am J Dent 2010;23:43-46).


Clinical significance: Incorporation of phyllosilicate in the experimental Portland cements did not improve the push-out strength compared to the commercially available ProRoot MTA. PBS immersion decreased the push-out strength of modified Portland cements while ProRoot MTA exhibited higher push-out strength after immersion in PBS.


Address: Dr. Francesco Iacono, Department of Oral Sciences, Alma Mater Studiorum, University of Bologna, Via San Vitale 59, 40125 Bologna, Italy. E-mail:



Research Article

Resistance to degradation of bonded restorations to simulated caries-affected primary dentin


Marcela  Marquezan, dds, ms, phd,  Raquel  Osorio, dds, ms, phd,  Ana  Lidia  Ciamponi, dds, ms, phd

&  Manuel Toledano, dds , ms , phd


Abstract: Purpose: To investigate the resistance to degradation of resin modified glass-ionomer cement (RMGIC) and adhesive/composite restorations in sound and simulated caries-affected dentin of primary teeth subjected to carious challenge using a pH-cycling model and load-cycling, by means of a microtensile test. Methods: Occlusal cavities were prepared in 60 sound exfoliated primary second molars. Half the specimens were submitted to pH-cycling to induce simulated caries lesion. The teeth were randomly restored with one of the two materials: (1) a RMGIC (Vitremer) and (2) a total-etch adhesive system (Adper Single Bond 2) followed by resin composite (Filtek Z100). After storage in distilled water at 37°C for 24 hours, control group specimens were subjected to test procedures while the specimens in the experimental groups were subjected to two different aging methods: load-cycling (50,000 cycles, 90N, 3Hz) or carious challenge (pH-cycling: alternately 8 hours in demineralizing and 16 hours in remineralizing solutions, for 10 days). Teeth were sectioned into 1 mm2 beams and tested to failure under tension. ANOVA and multiple-comparisons tests were used (P< 0.05). Results: Vitremer bond strength was not altered by the condition of dentin. Conversely, Adper Single Bond 2 showed significantly lower bond strength values when bonded to simulated caries-affected dentin. Load-cycling did not influence bond strength for any of the tested materials, while carious challenge resulted in a significant decrease in microtensile bond strengths of Adper Single Bond 2, but not of Vitremer restorations. (Am J Dent 2010;23:47-52).


Clinical significance: The use of Vitremer (RMGIC) is encouraged for pediatric patients with caries activity, since it satisfactorily bonded to simulated caries-affected dentin and resisted caries challenge.


Address: Dr. Raquel Osorio, Avda. de las Fuerzas Armadas 1, 1B, 18014 Granada, Spain.  E-mail:



Research Article

The occlusal precision of laboratory versus CAD/CAM

processed all-ceramic crowns


Sven  Reich, priv-doz, dr med dent,   Beate  Brungsberg, dentist,   Hubertus Teschner, dentist

&   Roland  Frankenberger, prof, dr med dent


Abstract: Purpose: The null hypothesis was tested: There is no difference between two all-ceramic crown systems, the Cerec method (CHAIR) and the IPS Empress method (LAB), with respect to occlusal precision and time expenditure for the dentist. Methods: 20 casts representing clinical situations were mounted in semi-adjustable articulators to serve as simulation models. The left lower first molars were prepared to receive feldspathic ceramic crowns. The minimum number of three (Min3) occlusal contacts and their desired location was defined on each crown before preparation. Two crowns were produced on each die: (CHAIR) was applied in order to simulate a chair-side treatment and [LAB] was applied to simulate the laboratory/clinical mode of production. Additionally the time required to perform the occlusal adjustment was measured. For occlusal analysis, the (Min3) were divided by the contacts that were “actually achieved” (ACT). Mean quotients for (LAB) and (CHAIR) were calculated (n = 20 each). The Wilcoxon signed rank test at P≤ 0.05 was applied to determine statistical significance. Results: The mean quotients MEAN QU (Min3)/(ACT) of 0.87 for (CHAIR) and 0.94 for (LAB) and the time expenditure for simulating intraoral occlusal adjustment of 3.44 minutes for (CHAIR) and 3.79 minutes for (LAB) did not differ significantly. (Am J Dent 2010;23:53-56).


Clinical significance: The clinical simulation showed that it was possible to achieve satisfactory occlusal precision either by the use of the conventional laboratory (LAB) and the CAD/CAM (CHAIR) method within similar time expenditure.



Address:  Priv.-Doz. Dr. Sven Reich, Department of Prosthodontics and Dental Materials, Medical Faculty, RWTH Aachen University, Pauwelsstrasse 30, D-52074 Aachen, Germany.  E-mail:




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