^{February 2018 Abstracts}

 

 

 

 

 

Effects of cigarette smoke on color change of resin composites

 

Gustavo Frainer Barbosa, dds, ms, phd  &  Sabrina Santos, bs

 

Abstract: Purpose: To evaluate the color change caused by cigarette smoke in both microhybrid and nanohybrid resin composites of three different manufacturers (Z100, Z350, Charisma, and Opallis). Methods: Samples of microhybrid (n= 40) and nanohybrid (n= 40) resin composites (A2) were prepared for each resin brand, totaling 240 samples. The samples were divided into subgroups: Control: control group without exposure; C5: five cigarettes, 25 minutes/exposure; C10: 10 cigarettes, 50 minutes/exposure; C20: 20 cigarettes, 100 minutes/exposure. The samples were then photographed and color change was measured by a computerized image analysis. L*a*b* values were obtained and color change was calculated. The Kolmogorov-Smirnov test was used to examine data normality; color change associated with an individual brand and the number of smoked cigarettes was analyzed with differentiation across the groups by the Tukey test (P≤ 0.05). The student t-test (P≤ 0.05) was used for the differentiation of inorganic fillers. Results: The color change was significant between five and 10 cigarettes (P= 0.01), between five and 20 cigarettes (P= 0.000), and not significant between 10 and 20 cigarettes (P= 0.585). Charisma showed a significant color change when compared to Opallis (P= 0.008) and Z100 and Z350 (P= 0.000). (Am J Dent 2018;31:3-6).

 

 

Mail: Dr. Gustavo Frainer Barbosa, Lutheran University of Brazil (ULBRA-Torres), Rua José Antônio Picoral 370/301, 95560-000 - Centro, Torres, RS - Brazil. E-mail: gfraibar@yahoo.com.br

 

 

Improved marginal adaptation of composite restorations by using different placement and light polymerization techniques

 

Bojana D. Ramic, dds, phd, Milica T. Premovic, dds, phd, Igor L. Stojanac, dds, phd, Milan R. Drobac, dds, phd &  Ljubomir M. Petrovic, dds, phd

 

Abstract: Purpose: To verify the influence of placement and polymerization technique on the gap width between dentin and composite restoration. Methods: Standardized cylindrical cavities (3 mm in diameter, 2 mm deep) with all margins in dentin were prepared on buccal and oral surfaces of 30 extracted human third molars. With regard to the different resin composite filling techniques used, the samples were randomly divided into three groups (n=20): bulk; incremental; pin. Each group was further subdivided into subgroups based on different light polymerization techniques: continuous (40 seconds); discontinuous (2 seconds of activation, followed by 10 seconds of dark interval, then light polymerization continued for 38 seconds). After finishing procedures, impressions were made using polyvinylsiloxane, and epoxy resin replicas were obtained and prepared for scanning electron microscopy. The percentage of the marginal gaps in relation to the whole margin was recorded and statistically analyzed (P≤ 0.05). Results: Marginal adaptation of composite restorations placed into the dentin cavities using pin and discontinuously light polymerized presented significantly better results than other two tested groups polymerized in the same manner. (Am J Dent 2018:31:7-12).

 

 

 

 

 

Mail: Dr. Bojana D. Ramic, Hajduk Veljkova 3, Novi Sad, 21000, Serbia. E-mail: bojana.ramic@mf.uns.ac.rs

 

 

In-office bleaching for the remineralization of enamel lesions filled with organic components of red wine

 

Yuichi  Kunimatsu, dds,  Junko  Iizuka, dds, phd,  Motoe  Taniguchi, dds, phd,  Yuko  Mikuni-Takagaki, phd &  Yoshiharu  Mukai, dds, phd

 

Abstract: Purpose: To investigate the effects of in-office bleaching on the remineralization of enamel lesions filled with organic components of red wine. Methods: Enamel specimens were exposed to 0.1% NaF solution for 1 minute immersed in red wine for 5 days at 37°C, and subjected to in-office bleaching followed by remineralization in 1.5 mM CaCl₂, 0.9 mM KH₂PO₄, 130 mM KCl, 20 mM HEPES, pH 7.0, at 37°C for 28 days. The presence of organic substances on the enamel surface was detected by Raman spectroscopy. The specimens were also subjected to transverse microradiography (TMR). Results: Raman spectroscopy of baseline lesions showed characteristic peaks at 1,300-1,600 cm⁻¹ which disappeared in bleached specimens. TMR showed that red wine formed subsurface lesions with surface content at approximately 22 mineral volume %. The integrated mineral loss (IML) was significantly lower in unbleached remin-eralized specimens than at baseline (P< 0.05). The IML of bleached remineralized specimens was lower than that of unbleached specimens, although not significantly (P> 0.05). Lesion depth was significantly lower in the bleached than in the unbleached group (P< 0.05). (Am J Dent 2018;31:13-16).

 

 

 

 

 

Mail: Dr. Junko Iizuka, Department of Oral Interdisciplinary Medicine, Graduate School of Dentistry, Kanagawa Dental University, 82 Inaoka-cho, Yokosuka, Kanagawa 238-8580, Japan.  E-mail: iizuka@kdu.ac.jp

 

 

A 24-week randomized clinical study investigating the anti-gingivitis efficacy of a 0.454% w/w stannous fluoride dentifrice

 

Charles Parkinson, phd,  Pejmon Amini, dds,  Jianming Wu, phd  &  John Gallob, dmd

 

Abstract: Purpose: To evaluate and compare gingival health, as measured by a bleeding index (BI), a modified gingival index (MGI), a dental plaque index (PI), and number of bleeding sites following twice daily use of an anhydrous 0.454% weight/weight (w/w) stannous fluoride dentifrice (Test Dentifrice) compared to a sodium monofluorophosphate (SMFP) dentifrice (Negative Control) over 24 weeks. Methods: This was a single-center, examiner-blinded, randomized [by gender and baseline mean MGI score (Low ≤ 2.00 /High > 2.00)], stratified, two-treatment arm, parallel group, 24-week clinical study in healthy adult volunteers with moderate gingivitis. At baseline, after abstaining from toothbrushing overnight, subjects underwent BI, MGI and PI assessments. Following randomization, eligible subjects underwent a thorough dental prophylaxis and flossing. After 12 and 24 weeks of twice daily brushing with their allocated treatment, subjects returned to the site with overnight plaque (having abstained from oral hygiene procedures for at least 8 hours) for BI, MGI and PI assessments. Results: Of 109 screened subjects, 104 were randomized and 98 completed the study. Statistically significant differences between treatments were observed in favor of the Test Dentifrice compared to the Negative Control dentifrice for all outcome measures including not only BI, MGI and PI indices but also number of bleeding sites (P< 0.0001 at Week 12 and Week 24 for all). Data observation showed that the percentage of sites that decreased was more, and those that increased was less, with the Test Dentifrice than with the Negative Control dentifrice at both 12 and 24 weeks. Treatments were generally well tolerated. (Am J Dent 2018;31:17-23).

 

 

 

 

 

 

Mail: Dr. Charles Parkinson, GSK Consumer Healthcare, St George’s Avenue, Weybridge, KT13 0DE, UK. E-mail: charles.x.parkinson@gsk.com

 

 

Influence of surface coating sealer on resin composite water absorption and discoloration: An in vitro study

 

Allegra Comba, dds, Elena Manzon, dds, Carlotta Giuliano, dds, Elena Farina, ms, Damiano Pasqualini, dds, Riccardo Michelotto Tempesta, dds, Elio Berutti, md, dds  &  Nicola Scotti, dds, phd

 

Abstract: Purpose: To evaluate the in vitro efficacy of surface coating sealer (SCS) in reducing the amount of water absorption and stain formation in resin composites. Methods: To evaluate the amount of water sorption, 40 stainless steel round molds (n=10 per composite) were filled with Filtek Supreme XTE; Venus Diamond; Clearfil Majesty ES-2; Gradia Direct Anterior. Groups were further divided into two subgroups (n=5) according to the presence/absence of SCS (Easy Glaze). Their masses were measured at baseline and reweighed at 1, 4, 12, and 20 weeks. For staining evaluation, 48 resin composite discs, 2 mm-thick, were obtained with the same composites and SCS was applied on a single surface of each sample. After baseline color assessment, samples were immersed in vials containing 5 mL of six different staining solutions. Color evaluation was performed again after 1, 4, 12, and 20 weeks. Three-way ANOVA was performed to evaluate differences in weight gain and color changes (P< 0.05). Results: A significant protective action of SCS (P< 0.001), but not of the composites (P= 0.366) was found. Differences in weight and color change were not influenced by the resin composite, but only by the presence of the coating on the surface of the samples. SCS are well-established materials for polishing and protecting composite restorations from water sorption and color changes. Different staining solutions can still produce different effects on resin composite. (Am J Dent 2018;31:24-28).

 

 

 

 

Mail; Dr. Nicola Scotti, Via Nizza 230, 10100, Turin, Italy. E-mail: nicola.scotti@unito.it

 

 

Impact of dentifrice abrasivity and remineralization time on erosive tooth wear in vitro

 

Sarah Buedel, bs,  Frank Lippert, msc, phd,  Domenick T. Zero, dds, ms,  George J. Eckert, mas & Anderson T. Hara, dds, mds, phd

 

Abstract: Purpose: To investigate the in vitro effects of simulated dentifrice slurry abrasivity (L-low, M-medium and H-high) and remineralization time (0, 30, 60 and 120 minutes) on erosive tooth wear. Methods: Enamel and root dentin specimens were prepared from bovine incisors (n= 8) and submitted to a cycling protocol including erosion, remineralization at the test times, and brushing with each of the tested slurries, for 5 days. Dental surface loss (SL) was determined by optical profilometry. Data was analyzed using mixed-model ANOVA and Fisher’s PLSD tests (alpha= 0.05). Results: SL generally increased along with the increase in slurry abrasive level, with significance dependent upon the specific substrate and remineralization times. H showed the highest SL on both enamel and dentin; remineralization for 30 minutes reduced SL significantly (P< 0.05), but only for enamel. M showed intermediate SL values, with remineralization benefit clearly seen only after 120 minutes of remineralization (P< 0.05). L caused the least SL for both enamel and dentin, which was further reduced after remineralization for 120 and 30 minutes, respectively (both P< 0.05). Overall, root dentin had significantly higher SL than enamel. Less abrasive dentifrice slurries were able to reduce toothbrushing abrasion on both enamel and root dentin. This protection was enhanced by remineralization for all abrasive levels on enamel, but only for L on root dentin. (Am J Dent 2018;31:29-33).

 

 

Mail: Dr. Anderson T. Hara, Cariology, Operative Dentistry and Dental Public Health, Indiana University School of Dentistry, 415 N. Lansing Street, Indianapolis, IN 46202-2876, USA. E-mail: ahara@iu.edu

 

 

 

Influence of dentin and enamel on the fracture resistance of restorations at several thicknesses

 

Paul de Kok, dds,  Cornelis  J.  Kleverlaand, phd,  Ruud  H.  Kuijs, phd, ddsc,  M.  Arife  Öztoprak &  Albert J. Feilzer, phd, dds

 

Abstract: Purpose: To investigate the effect of substrate and thickness on the fracture resistance of bonded dental restorative materials. Methods: Cylindrical restorations (d = 4.0 mm) of resin composites Filtek Supreme XTE, Clearfil AP-X, Lava Ultimate and glass-ceramic IPS e.max CAD were fabricated at thicknesses of 0.5 mm, 1.0 mm and 2.0 mm respectively (n = 10 per group) and adhesively bonded to bovine enamel or dentin. The load to failure (LtF in N) of all specimens was determined in a universal testing machine and two one-way ANOVAs with a post hoc LSD tests and separate independent samples t-tests, performed at a significance level of 5%. Results: At 0.5 and 1.0 mm, direct resin composites bonded to dentin showed a higher LtF than when bonded to enamel, while the indirect materials showed reversed results (P< 0.05). At 2.0 mm there was no difference except for LU. A direct relationship between LtF and increasing thicknesses on enamel was found, while on dentin the LtF of direct resin composite restorations was less dependent on the thickness. (Am J Dent 2018;31:34-38).

 

 

Mail: Paul de Kok, Academic Centre for Dentistry Amsterdam (ACTA), Gustav Mahlerlaan 3004, 1081 LA Amsterdam, The Netherlands. E-mail: p.d.kok@acta.nl

 

 

Fracture resistance of three different all-ceramic crowns: In vitro study

 

Ammar M. Alarwali, bds, mdsc, Muralithran G. Kutty, bsc, msc, phd, Afaf Y. Al-Haddad, bds, mdsc, phd & Maria Angela G. Gonzalez, ddm, mph, msd

 

Abstract: Purpose: To evaluate the fracture resistance and failure mode of three different all-ceramic crowns; CEREC Bloc, IPS e.Max Press and Cercon in a simulated clinical situation. Methods: 30 extracted maxillary premolars were prepared and randomly assigned to three groups equally according to the type of crown used. The first was the CEREC group: monolithic feldspathic crowns (CEREC Blocs). The second was the E.Max group: monolithic lithium disilicate crowns (IPS e.Max Press). The third group was the Cercon group: bilayered partially stabilized zirconia crowns (Cercon). All crowns were cemented using dual-cured resin cement (ParaCore). The specimens were then subjected to thermocycling (5-55°C/500 cycles) and loaded to failure at an angle of 45° to the occlusal surface of the crown. Failure data was statistically analyzed using one-way ANOVA and Tukey’s HSD post hoc test at α= 0.05. Fractographic analysis was performed to determine the fracture modes of the failed specimens. Results: The mean fracture values for CEREC, E.Max and Cercon groups were 387 ± 60 N, 452 ± 86 N, and 540 ± 171 N, respectively. Significant differences were found between CEREC and Cercon groups (P< 0.05). Catastrophic fracture within the ceramic crown was the major failure mode of the CEREC group. For E.Max and Cercon groups, the major failure mode was exhibiting severe tooth fracture while the ceramic crown remained intact. (Am J Dent 2018;31:39-44).

 

 

 

 

Mail: Dr. Ammar M. Alarwali, Department of Restorative Dentistry, Faculty of Dentistry, University of Malaya, 50603 Kuala Lumpur, Malaysia. E-mail: ammar_alarwali@yahoo.com

 

 

Effect of surface characteristics of soft liners and tissue conditioners and saliva on the adhesion and biofilm formation

 

Camila Cristina De Foggi, dds, msc, phd, Marina Siqueira Bambini Ayres, dds, Guilherme Paladini Feltrin, dds, Janaina Habib Jorge, dds, msc, phd  &  Ana Lúcia Machado, dds, msc, phd

 

Abstract: Purpose: To investigate the influence of surface characteristics and saliva on the adhesion and biofilm formation of Candida glabrata and methicillin-resistant Staphylococcus aureus (MRSA) to soft liners and tissue conditioners. Methods: For each material (Ufi Gel P - UG; Sofreliner S - SS; Trusoft - TR; Coe Comfort - CC; Softone - ST), specimens were prepared and roughness (Ra), hydrophobicity (water contact angles-WCA) and surface free energy (SFE) were measured. Surface morphology was also analyzed using scanning electron microscopy (SEM). Specimens were incubated in C. glabrata or MRSA suspensions for 90 minutes (adhesion) or 48 hours (biofilm). The absorbance (AB) was measured by XTT assay. Experiments were performed using specimens that were either uncoated or had been coated with saliva. Data were analyzed using one- or two-way ANOVAs, followed by Tukey’s test (α= 0.05). Results: TR exhibited the highest Ra and UG the lowest. SEM images also showed that UG and SS had smooth surfaces, while TR presented several irregularities and pores. In the absence of saliva, UG and SS presented higher WCA and lower SFE than the other materials. XTT results showed that, in the C. glabrata adhesion assay, the AB value was higher for TR followed by UG > CC > SS > ST. For the biofilm formation of C. glabrata, AB values were in the following order TR > CC = UG > ST = SS. In the adhesion assay, AB values obtained for MRSA were TR > UG = CC > ST > SS and for the biofilm formation were TR > ST > CC > UG > SS. Saliva decreased the WCA and increased the SFE for all materials. In general, the presence of saliva decreased the adhesion and biofilm formation of both microorganisms to the acrylic-based material (TR) and tissue conditioners (CC and ST), and increased for the silicone-based soft liners (UH and SS). Surface characteristics and the influence of saliva varied among materials. Roughness seemed to favor C. glabrata and MRSA adhesion and biofilm formation. (Am J Dent 2018;31:45-52).

 

 

 

 

Mail: Dr. Janaina Habib Jorge, Department of Dental Materials and Prosthodontics, São Paulo State University (UNESP), Dental School, Campus Araraquara, R. Humaitá, no. 1680, Araraquara, SP, Brazil CEP: 14801-903. E-mail: janainahj@foar.unesp.br

 

 

Penetration and bactericidal efficacy of two oral care products in an oral biofilm model

 

Junbo Xiang, phd,  Hongmei Li, ms,  Boqun Pan, bs,  Jinlan Chang, bs,  Yanyan He, ms,  Tao He, dds, phd, Ross Strand, phd,  Yunming Shi, phd  &  Weili Dong, phd

 

Abstract: Purpose: To investigate the immediate penetration and bactericidal effect of two oral care products marketed in China on an intact natural plaque biofilm model at different time points. Methods: Eight subjects (aged 20 to 30 years; Turesky Plaque Index Score 2 to 3) were enrolled in the study according to the inclusion criteria. Plaque accumulators were worn by the subjects for 6 and 48 hours for harvesting the dental biofilm. Then the biofilms from different groups were stained with the LIVE/DEAD BacLight fluorescence system to investigate the changes in thickness and fluorescence intensity of living bacteria in biofilm 5 and 15 minutes post-treatment with a mouthrinse containing 0.074% cetylpyri-dinium chloride (1-minute treatment) or a toothpaste supernatant containing 1.16% stannous chloride (2-minute treatment). In addition, a specific Sn²⁺ probe was utilized to evaluate the penetration of Sn²⁺ in the biofilm. Fluorescent images were collected using confocal laser scanning microscopy. Analysis of covariance was used for statistical analyses. All comparisons were two-sided using a 5% level of significance. Results: The thickness of generated plaque biofilm increased gradually from 7.35±4.22 μm at 6 hours to 16.73±7.38 μm at 48 hours (P< 0.05), whereas the thickness and fluorescence intensity of living bacteria stayed unchanged over time. After the treatment of toothpaste supernatant, the ratios of living bacteria thickness and fluorescence intensity of 6- and 48-hour plaque biofilm were significantly decreased (P< 0.05). Treatment of mouthrinse reduced the ratio of living bacteria thickness, but showed no significant impact on overall fluorescence intensity of living bacteria. For 48-hour biofilm, toothpaste supernatant significantly reduced fluorescence intensity of living bacteria from outer layer through inner layer, whereas the mouthrinse showed bactericidal effect only in the outer layer and middle layer. A wide distribution of Sn²⁺ was shown in the biofilm with the treatment of the tested toothpaste. (Am J Dent 2018;31:53-60).

 

 

 

Mail: Dr. W. Dong, Department of Periodontology, School & Hospital of Stomatology, Wuhan University, Wuhan 430072, China.  E-mail: zdwlss272@whu.edu.cn