^{April 2016 Abstracts}

Effects of light-, self-, and tack-curing on degree of conversion and physical strength of dual-cure resin cements

 

 

Liang Chen, phd,  Byoung In Suh, phd,  Christine  Gleave, ms,  Won Jun  Choi,  Jihye  Hyun  &  Jiyun  Nam

 

 

Abstract: Purpose: To evaluate the polymerization degree of conversion (DC) and physical strength of dual-cure cements with tack-curing, and compare them to those with light-curing and self-curing resins. Methods: Four dual-cure resin cements were evaluated by DC and diametral tensile strength (DTS) tests with three different polymerization methods: Light-cure (photo-polymerization 40 seconds, self-curing 30 minutes); Self-cure (self-curing 30 minutes); and Tack-cure (photo-polymerization 3 seconds, self-curing 30 minutes). Polymerization degree of conversion was determined using Fourier transform infrared spectroscopy, and calculated based on the ratio changes of aliphatic-to-aromatic C=C IR absorption peaks before and after polymerized. Specimens for DTS (n = 10) were prepared using circular molds (6.0 mm in diameter and 3.0 mm in height) and tested after 24-hour water storage. Data were analyzed by two-way ANOVA. Multiple post-hoc pairwise comparisons were performed by t-test when significant effects were found across the factors (α = 0.05). Results: The Self-cure groups had slow initial curing rate, resulting in the lower DC than both the Light-cure and Tack-cure groups. After 30 minutes of polymerization, only in the RelyX Ultimate group, light-curing resulted in higher DC than tack-curing, which resulted in higher DC than self-curing (P< 0.05). The self-cure of resin cements resulted in a significantly lower DTS only for RelyX Ultimate cement (P< 0.05). There was no significantly different DTS between the Tack-cure and Light-cure groups for all of the resin cements. For all of the three curing modes, RelyX Ultimate cements had the lowest DTS among the four cements tested in this study. (Am J Dent 2016;29:67-70).

 

 

 

 

 

Mail: Dr. Liang Chen, BISCO, Inc., 1100 W Irving Park Road, Schaumburg, IL 60193, USA. E-mail: lchenchem@yahoo.com

 

 

Effect of Biodentine on secondary caries formation: An in vitro study

 

Betül Memis Özgül, dds, phd, R. Ebru Tirali, dds, phd  &  S. Burcak Cehreli, dds, phd

 

Abstract: Purpose: To compare the effects of two materials, Biodentine and conventional glass-ionomer cement (CGIC), on secondary caries formation around restorations when used as a dentin replacement material. Methods: 30 approximal cavities were prepared on mesial and distal surfaces of 15 caries-free human premolar teeth extracted for orthodontic or periodontal reasons. Cavities were filled with A: Biodentine as a base + Filtek Z250 composite (n= 15) or B: CGIC as a base + Filtek Z250 composite (n= 15). The materials were applied according to the manufacturers’ instructions. Teeth were thermocycled, and placed in a demineralizing solution for 5 weeks. Secondary caries formation was assessed using the International Caries Detection and Assessment System (ICDAS) II and quantitative computer-aided image measurement of caries depth. Results: The computer-aided measurements showed that the Biodentine group had significantly lower lesion depth measurements than the CGIC group (P= 0.004). However, there was no significant difference among the groups based on the ICDAS II scores (P> 0.05). (Am J Dent 2016:29:71-74).

 

 

Mail: Dr. Betül Memis Özgül, Department of Pediatric Dentistry, Faculty of Dentistry, Baskent UniversityTaskent cad. No: 107 06450, Ankara, Turkey. E-mail: dtbetulmemis@hotmail.com

 

 

Clinical and spectrophotometric evaluation after chlorhexidine use in periodontal flap surgery: A prospective randomized clinical trial

 

Lorenzo Bevilacqua, dds, ms, Giuliana Liani, dh, Gaetano Castronovo, md, dds & Fulvia Costantinides, dds, ms

 

Abstract: Purpose: To evaluate by a clinical spectrophotometric analysis the staining side effect of a 0.2% chlorhexidine (CHX) mouthrinse containing an anti-discoloration system (ADS) compared with a 0.12% and a 0.2% CHX mouthrinse, after periodontal surgery. The efficacy of the products and the patient’s opinion and acceptance were also assessed. Methods: The study was carried out on 60 subjects scheduled for periodontal flap surgery at the Unit of Periodontology and Dental Hygiene (University of Trieste, Italy). After surgery, the subjects were randomly prescribed to rinse for 1 week with 10 ml of a 0.12% CHX (Group 1), 0.2% CHX (Group 2) or 0.2% ADS CHX (Group 3). Before surgery (T0), 7 days (T1) and 14 days (T2) after surgery, following variables were recorded: gingival parameters at the surgically treated sites (Full-Mouth Plaque Score, Full-Mouth Bleeding Score and Modified Gingival Index), tooth pigmentation measured as ΔE, patient perception and acceptance of the mouthrinses. Results: 53 subjects completed the study. The difference among treatments related to gingival variables was not statistically significant. No statistical differences were found for dental pigmentation among the mouthrinses over time nor for discomfort at each follow-up examination. A slightly less acceptance rate was observed for 0.2% CHX. The following conclusions were drawn: (1) 0.2% CHX with ADS did not cause less brown pigmentation than the 0.2% CHX or than the 0.12% CHX; (2) 0.2% ADS CHX was as effective as CHX without ADS in reducing gingival signs of inflammation in the post-surgical early healing phase; (3) 0.2% CHX showed the lowest score in terms of taste acceptance compared with 0.12% and ADS CHX. (Am J Dent 2016;29:75-80).

 

 

 

 

 

 

Mail: Dr. Lorenzo Bevilacqua, School of Dental Sciences, Piazza dell’Ospitale 1, 34129 Trieste, Italy.  E-mail: l.bevilacqua@fmc.units.it

 

In situ anticariogenic activity of free fatty acids after sucrose exposure to oral biofilms formed on enamel

 

Rodrigo A. Giacaman, dds, phd, Ricardo Valenzuela-Ramos, dds  &  Cecilia Muñoz-Sandoval, dds

 

Abstract: Purpose: To test whether the effect of sucrose on enamel is hampered by immediate free fatty acids exposure to the oral biofilm formed under a highly cariogenic environment, in situ. Methods: A split-mouth, cross-over and double-blind in situ experiment was carried out with 11 volunteers who wore palatal appliances containing bovine enamel slabs. In two 15-day phases, volunteers dripped 20% sucrose onto the slabs eight times per/day for 5 minutes followed by 5 additional minutes with suspensions of 10 mM oleic, linoleic or stearic acid or sucrose (caries-positive control), four times/day. Biofilms were analyzed for biomass, bacteria and polysaccharide formation and enamel demineralization was estimated by surface microhardness. Results: Biofilms exposed to oleic and linoleic acids showed significantly lower biomass than the control. S. mutans counts were reduced upon linoleic acid exposure (P< 0.05). All free fatty acids reduced polysaccharide formation (P< 0.05). Slabs exposed to 20% sucrose followed by free fatty acids had significantly lower demineralization than those exposed to sucrose alone, with reductions of 33%, 27% and 20% for linoleic, oleic and stearic acid, respectively. Data suggest that unsaturated free fatty acids exposed after sucrose might potentially reduce cariogenicity of the oral biofilm formed on enamel in situ, but further clinical confirmation is required. (Am J Dent 2016;29:81-86).

 

 

 

 

Mail: Dr. Rodrigo A. Giacaman, School of Dentistry, 2 Norte 685, Talca, Chile. E-mail: giacaman@utalca.cl

 

 

The antimicrobial potential of stevia in an in vitro microbial caries model

 

Maryam Kishta-Derani, dds, ms,  Gisele F. Neiva, dds, ms, ms,  James R. Boynton, dds, ms, Youngjoo E. Kim, dds &  Margherita Fontana, dds, phd

 

Abstract: Purpose: To determine the effect of stevia on caries development when incorporated into a cariogenic diet in a controlled microbial caries model. Methods: 56 bovine tooth specimens (4 × 4 mm) were divided into four groups, each secured in a caries-forming vessel. All vessels were placed on an electric stirrer inside a 37°C incubator. The specimens were inoculated with Streptococcus mutans, and exposed for 4 days to circulating cycles of tryptic soy broth supplemented with 5% sucrose-TSBS (three ×/day), and a mineral wash solution. Between TSBS cycles (three x/day), each group received one of four experimental solutions: phosphate buffer (PBS-negative control), 0.5% stevia solution, 5% stevia solution, or 5% xylitol solution. Development of caries lesions was analyzed using enamel surface hardness. Difference in Vickers Hardness between pre and post-treatment was calculated to determine caries development. Plaque was dislodged from six specimens per group, and the CFU/ml calculated. Data were analyzed using ANOVA at 95% confidence level, and individual group differences calculated using Tukey’s test. Results: 5% xylitol resulted in significantly less plaque at the end of the study compared to PBS and 5% stevia, but not significantly different than 0.5% stevia. 5% stevia had significantly softer lesions than the other groups, while there was no significant difference in hardness scores between 5% xylitol, 0.5% stevia and PBS. (Am J Dent 2016;29:87-92).

 

 

 

 

 

Mail: Dr. Margherita Fontana, Dept. Cariology, Restorative Sciences and Endodontics, School of Dentistry, University of Michigan, 1011 N. University Dr. 2393, Ann Arbor, MI 48109-1078, USA. E-mail: mfontan@umich.edu

 

 

Efficacy of an experimental toothpaste containing 5% calcium sodium phosphosilicate in the relief of dentin hypersensitivity: An 8-week randomized study (Study 1)

 

Farzana Sufi, msc, Claire Hall, msc, Stephen Mason, Phd, David Shaw, msc, Liam Kennedy, msc, cstat &  John T. Gallob, dmd

 

Abstract: Purpose: To evaluate the efficacy of an experimental toothpaste containing 5% (w/w) calcium sodium phosphosilicate (CSPS) in relieving dentin hypersensitivity (DH) compared with control toothpastes containing no known anti-sensitivity ingredients. Methods: This was the first of two exploratory, randomized, four-treatment, examiner-blind, parallel-design, single-site, 8-week studies in healthy subjects with self-reported and clinically diagnosed DH. The experimental toothpaste contained 5% CSPS with a modified surfactant system, developed to enhance its organoleptic properties. Efficacy was evaluated against an abrasivity-matched placebo formulation (0% CSPS) with additional abrasive silica replacing the CSPS, and two commercially available fluoride toothpastes as controls. After an initial lead-in period, subjects were randomized to one of the four study treatments and instructed to brush twice daily for the next 8 weeks. DH was assessed at baseline and following 4 and 8 weeks of treatment by response to tactile and evaporative (air) stimuli, and using a Dentine Hypersensitivity Experience Questionnaire (DHEQ; a validated quality-of-life measure for DH). Results: A total of 134 subjects were randomized and completed the study. All treatments demonstrated statistically significant reductions in sensitivity from baseline at Week 4 and Week 8 for each clinical measure of sensitivity (all P≤ 0.001). The 0% CSPS toothpaste demonstrated small but statistically significant reductions in Schiff sensitivity score compared with the other study toothpastes at Week 8 (all P< 0.05), whereas the experimental 5% CSPS toothpaste significantly improved the tactile threshold at Week 4 compared with the 0% CSPS toothpaste (P= 0.0467). The DHEQ responses did not reveal any consistent statistically significant within-treatment changes from baseline or between-treatment differences. Correlation analysis showed weak-to-moderate associations between the DHEQ outcomes and clinical endpoints. Study treatments were well tolerated. The treatment differences observed in this exploratory study were small and inconsistent between measures. The reasons for the inconsistencies are not clear but may be related to the properties of the abrasivity-matched 0% CSPS formulation, with the increased level of dental silica conferring an advantage in terms of reducing DH. The ability of dental silicas to occlude exposed dentin tubules and thereby reduce DH has been demonstrated in previous studies, and may warrant further clinical investigation. (Am J Dent 2016;29:93-100).

 

 

 

 

Mail: Ms. Farzana Sufi, Oral Care Medical Affairs, Research & Development, GSK Consumer Healthcare, St George’s Avenue, Weybridge, Surrey, KT13 0DE, UK. E-mail: farzana.x.sufi@gsk.com

 

Efficacy of an experimental toothpaste containing 5% calcium sodium phosphosilicate in the relief of dentin hypersensitivity: An 8-week randomized study (Study 2)

 

Farzana Sufi, msc,  Claire  Hall, msc,  Stephen  Mason, phd,  David  Shaw, msc,  Jeffery Milleman, dds, mpa &  Kimberly  Milleman, bsed, ms

 

Abstract: Purpose: To compare the efficacy of an experimental toothpaste containing 5% (w/w) calcium sodium phosphosilicate (CSPS) in relieving dentin hypersensitivity (DH) with that of control toothpastes containing no known anti-sensitivity ingredients. Methods: This was the second of two exploratory, randomized, four-treatment, examiner-blind, parallel-design, single-site, 8-week studies in healthy subjects with self-reported and clinically diagnosed DH. After an initial lead-in period, subjects were randomized to one of four study treatments: the experimental toothpaste containing 5% CSPS with a modified surfactant system, developed to enhance its organoleptic properties; an abrasivity-matched placebo formulation (0% CSPS) with additional abrasive silica replacing the CSPS; or one of two commercially available fluoride toothpastes as controls. Subjects were instructed to brush twice daily for the next 8 weeks. DH was assessed at baseline and following 4 and 8 weeks of treatment by response to tactile and evaporative (air) stimuli, and using a Dentine Hypersensitivity Experience Questionnaire (DHEQ; a validated quality of life measure for DH). Results: A total of 137 subjects were included in the efficacy analysis. The experimental 5% CSPS toothpaste demonstrated statistically significant reductions from baseline in sensitivity at Week 4 and Week 8 for each clinical measure (all P< 0.01). It also demonstrated significantly greater improvements in DH compared with the two control toothpastes for the majority of clinical measures at Week 4 (P≤ 0.01) and for all clinical measures at Week 8 (all P < 0.01). The abrasivity-matched 0% CSPS toothpaste was associated with similar outcomes to the 5% CSPS toothpaste. The DHEQ responses did not reveal any consistent statistically significant within-treatment changes from baseline or between-treatment differences. Strong correlations with DHEQ outcomes were only observed for the subjects’ sensitivity rating in response to evaporative (air) stimuli at Week 8. Study treatments were well tolerated. (Am J Dent 2016;29:101-109).

 

 

Mail: Ms. Farzana Sufi, Oral Care Medical Affairs, Research & Development, GSK Consumer Healthcare, St George’s Avenue, Weybridge, Surrey, KT13 0DE, UK.  E-mail: farzana.x.sufi@gsk.com

 

 

Chemical and mechanical degradation of nano-ionomer after two different surface protections: An in vitro study

 

Iman Ibrahim ElSayad, msc, phd  &  Eman Aly Abou Auf, msc, phd

 

Abstract: Purpose: To evaluate the effect of food-simulating liquids prior to brushing on surface roughness of a nano-ionomer restorative protected with two surface protection agents. Methods: 90 specimens were divided into three groups according to surface protection; the first group: no surface protection; the second group: copal varnish; the third group: light cure Ketac Glaze. Each group was subdivided into three subgroups relative to the immersion solution: artificial saliva; citric acid 0.02 M; or 50% ethanol. Specimens were stored for 7 days in one of the solutions in an incubator. One surface of each specimen was subjected to brushing with a sonic electric toothbrush while the other surface was not brushed. Surface roughness was measured with a stereo-microscope. Data were analyzed using one way ANOVA followed by paired t-test (P< 0.05). Results: The surface roughness of the nano-ionomer specimens immersed in ethanol was significantly higher than those immersed in citric acid. No significant differences were found between surface protection agents or between brushed and un-brushed specimens. The highest surface roughness mean value was recorded with brushed unprotected specimens immersed in ethanol. While the lowest surface roughness mean value was recorded with un-brushed copal varnish protected specimens immersed in ethanol. (Am J Dent 2016;29:110-114).

 

 

 

 

 

Mail: Dr. Iman Ibrahim ElSayad, Department of Operative Dentistry, Faculty of Oral and Dental Medicine, Cairo University, 39 Wezarat Al Zeraa, Doki, Giza 12311, Egypt. E-mail: imsayad@gmail.com

 

 

Demineralization of resin-sealed enamel by soft drinks in a clinically relevant pH cycling model

 

Agata  A.  Bartels, dmd, ms,  Carla  A.  Evans, dds, msc,  Grace  Viana, msc  &  Ana  K.  Bedran-Russo, dds, ms, phd

 

Abstract: Purpose: To compare the in vitro protective effect of orthodontic sealants on the enamel demineralization under a soft drink-induced erosive challenge. Methods: The facial surfaces of bovine incisors were sectioned into 5 mm × 4 mm × 4 mm enamel blocks. Specimens were randomly assigned to three surface protection measures: control (exposed enamel), coating with Transbond XT (unfilled resin primer), or coating with Opal Seal (filled and fluoride releasing primer). Thermocycling was used to simulate aging. The specimens were pH cycled through an acidic buffer, test beverage and a neutral buffer for a total of 7 days. Test beverages included water, Diet Mountain Dew, and Coke Classic. Quantitative light-induced fluorescence (QLF) images were taken at baseline and after aging. Final QLF images were taken to evaluate the demineralization of enamel. Data were analyzed statistically using a two-way ANOVA to compare the interaction between enamel surface protection and beverages as well as one-way ANOVA to compare surface protection and the test beverage levels. Results: A statistically significant interaction was found between the surface protected groups and the test beverage groups (P< 0.05). Statistically significant differences were found among the test beverage groups (P< 0.05) and among the surface protection groups (P< 0.05). Coke Classic went through the sealant layer resulting in high enamel demineralization. Enamel coating with Opal Seal significantly reduced the erosive attack of beverages. (Am J Dent 2016;29:115-119).

 

 

 

Mail: Dr. Ana Bedran-Russo, Department of Restorative Dentistry, Room 531, College of Dentistry, University of Illinois at Chicago, 801 S. Paulina Street, Chicago, IL 60612, USA.  E-mail: bedran@uic.edu

 

 

A randomized clinical trial to assess anti-plaque effects of an oral hygiene regimen with a stannous-containing sodium fluoride dentifrice, advanced manual toothbrush, and CPC rinse

 

Xiping Feng, dds, phd, Tao He, dds, phd, Michelle Cao, bs, Yanyan He, ms  &  Nelson Ji, bs

 

Abstract: Purpose: To assess the anti-plaque efficacy of an oral hygiene regimen comprised of a stannous-containing sodium fluoride dentifrice, advanced manual toothbrush, and a cetylpyridinium chloride (CPC) rinse compared to a negative control regimen. Methods: This was a 4-week randomized and controlled, parallel group, single-center, single-blind, clinical trial in generally healthy Chinese adults with existing dental plaque. Following a 1-week acclimation period and cessation of overnight oral hygiene prior to the baseline examination, overnight pre-brushing plaque levels were assessed via digital plaque imaging analysis (DPIA). Subjects were randomly assigned to either: (1) the test regimen of a stannous-containing sodium fluoride dentifrice (Crest Pro-Health Expert), an advanced manual toothbrush with CrissCross bristles (Crest Pro-Health manual toothbrush), and a 0.07% CPC rinse (Crest Pro-Health Multi-Protection); or (2) the negative control regimen group, a 0.243% sodium fluoride dentifrice (Crest Cavity Protection) and a soft flat trim manual toothbrush (Crest MeiLiLiangJie). Subjects returned at Week 2 and Week 4 following twice daily use of their assigned products, again following pre-visit cessation of overnight oral hygiene, for DPIA evaluation of overnight plaque levels. Results: 35 fully evaluable subjects completed the trial.  At Week 2, the pre-brushing overnight average DPIA plaque scores for the advanced products regimen group were 72.4% statistically significantly lower relative to the control group (P< 0.0001). At Week 4, the mean plaque inhibition benefit provided by the regimen group was 76.8% greater than the control group (P< 0.0001). All products were well-tolerated. (Am J Dent 2016;29:120-124)

 

 

Mail: Dr. X. Feng, Department of Preventive and Pediatric Dentistry, Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, PR China. E-mail: fxiping1808@qq.com