^{April 2017 Abstracts}

 

 

 

 

Ion release and in vitro enamel fluoride uptake associated with pit

and fissure sealants containing microencapsulated remineralizing agents

 

Brant D. Burbank, bs, msob, Ryan L. Cooper, bs, msob, Alyssa Kava, bs, Jennifer M. Hartjes, bs,

William A. McHale, bs, Mark A. Latta, bs, ms, dmd  &  Stephen M. Gross, phd

 

Abstract: Purpose: To determine if pit-and-fissure sealants with microencapsulated remineralizing agents with sustained release of fluoride, calcium and phosphate ions could promote enamel fluoride uptake by demineralized tooth structure. Methods: Sealants that contained 5 w/w% microcapsules with aqueous solutions of 5M Ca(NO₃)₂ or 0.8M NaF or 6.0M K₂HPO₄ or a mixture of all three were prepared. Ion release profiles were measured as a function of time. Enamel fluoride uptake by demineralized tooth structure was determined. Results: Sustained release of fluoride, calcium and phosphate ions from a sealant was demonstrated. Fluoride uptake by demineralized enamel was significantly increased compared to a control sealant manufactured without microcapsules (P< 0.01). Bovine enamel that contained 2.2±2.1 μg F/g of enamel prior to exposure to a sealant without microcapsules had 2.3±0.5 after 90 days. Enamel exposed to sealant with 5w/w% NaF microcapsules went from 3.5±3.5 μg F/g of enamel prior to exposure to 148±76 after 90 days. Enamel exposed to sealant with 2 w/w% NaF, 2 w/w% Ca(NO₃)₂ and 1 w/w% K₂HPO₄ microcapsules went from 1.7±0.7 μg F/g of enamel prior to exposure to 190±137 after 90 days. (Am J Dent 2017;30:59-64).

 

 

Mail: Dr. Stephen Gross, School of Dentistry, Creighton University, 2500 California Plaza, Omaha, NE 68178, USA. E-mail: stephengross@creighton.edu

 

 

 

Light energy transmission and Vickers hardness ratio of bulk-fill resin

based composites at different thicknesses cured by a dual-wave or a

single-wave light curing unit

 

Ario Santini, md, bds, dds, phd,  Reem Khalil Naaman, bds, mclindent  &  Mohammed Saeed Aldossary, bds, mclindent

 

Abstract: Purpose: To quantify light energy transmission through two bulk-fill resin-based composites and to measure the top to bottom surface Vickers hardness ratio (VHratio) of samples of various incremental thicknesses, using either a single-wave or dual-wave light curing unit (LCU). Methods: Tetric EvoCeram Bulk Fill (TECBF) and SonicFill (SF) were studied. Using MARC-RC, the irradiance delivered to the top surface of the samples 2, 3, 4 and 5 mm thick (n= 5 for each thickness) was adjusted to 800 mW/cm² for 20 seconds (16 J/cm²) using either a single-wave, Bluephase or a dual-wave, Bluephase G2 LCUs. Light energy transmission through to the bottom surface of the specimens was measured at real time using MARC-RC. The Vickers hardness (VH) was determined using Vickers micro hardness tester and the VHratio was calculated. Data were analyzed using a general linear model in Minitab 16; ɑ= 0.05. Results: TECBF was more translucent than SF (P< 0.05). The mean VHratio was higher than 80% in 2, 3 and 4 mm increment thickness for both materials (except for 4 mm TECBF when cured with the dual-wave Bluephase G2). SF showed significantly higher VH ratio than TECBF at all different thickness levels (P< 0.05), except at the 2 mm level (P> 0.05). TECBF showed significantly greater VH ratio when cured with the single-wave Bluephase than when using the dual-wave Bluephase G2 (P< 0.05). (Am J Dent 2017;30:65-70).

 

 

Mail: Dr. Mohammed Saeed Aldossary, P.O.Box 13743 Riyadh 11414, Saudi Arabia. E-*: msfd99@hotmail.com

 

 

Effect of oxygen inhibition in universal adhesives on dentin bond durability

and interfacial characteristics

 

Akimasa Tsujimoto, dds, phd, Wayne W. Barkmeier, dds, ms, Toshiki Takamizawa, dds, phd,

Mark A. Latta, dmd, ms  &  Masashi Miyazaki, dds, phd

 

Abstract: Purpose: To evaluate the effects of oxygen inhibition of universal adhesive on dentin bond durability and interfacial characteristics. Methods: The three universal adhesives used were Scotchbond Universal Adhesive, Prime & Bond Elect, and G-Premio Bond. Shear bond strength (SBS) and shear fatigue strength (SFS) of resin composite bonded to adhesive with and without an oxygen inhibited layer (OIL) on dentin using total-etch and self-etch modes were determined. Surface free energy (SFE) and SFE parameters of cured adhesive with and without an OIL on dentin using total-etch and self-etch modes were also measured by the sessile drop method. Results: The presence of an OIL in universal adhesives promoted higher SBS and SFS regardless of etching mode. In addition, regardless of adhesive type and etching modes, the specimens with an OIL showed a higher ratio of SFS/SBS than those without an OIL. Further, the SFEs, especially total SFE, polarity force and hydrogen bonding force, of cured adhesives with an OIL were significantly higher than those without an OIL. (Am J Dent 2017;30:71-76).

 

 

 

 

Mail: Dr. A. Tsujimoto, 1-8-13 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan; E-mail: tsujimoto.akimasa@nihon-u.ac.jp

 

 

A global approach to assess the economic benefits of increased consumption

of sugar-free chewing gum

 

Reinhard Rychlik, md, phd, phd,  Fabian Kreimendahl, msc, Cornelia Blaich, dmd, Hanny Calache, phd, mdsc,

Franklin Garcia-Godoy, dds, ms, phd, phd, Elizabeth Kay, bds, mph, phd, Yan Si, phd, David Zilberman, phd

&  Stefan Zimmer, dds, mphd, phd

 

Abstract: Purpose: To analyze the influence of increasing the average consumption of sugar-free gum (SFG) in 25 industrialized countries on dental expenditures due to caries by the national health care systems. It was assumed that large cost savings were possible, because the regular consumption of SFG significantly reduces the relative risk of caries and therefore, improves dental health, which reduces expenditures on dental treatments. Methods: A budget impact analysis (BIA) was performed to model the decrease in the relative risk of caries and the subsequent cost savings for dental care. Annual consumption of SFG, dental expenditures due to caries, chewing frequencies by age groups and the relative risk reduction for caries due to the consumption of SFG were identified and used as model parameters. Three different scenarios for the increase in the number of SFG were calculated. Besides overall results for all countries together, analyses were conducted for countries grouped by regions and the Human Development Index (HDI). Results: For the entity of all 25 analyzed countries together, possible annual cost savings range from US$805.77 M in the scenario with the lowest increase of SFG consumption up to US$18,248 billion in the scenario with the biggest increase of SFG consumption. Europe and the USA show potential cost savings of US$1,061 billion and US$2,071 billion per year, respectively, if all chewers increase their consumption of SFG by 1 piece per day. The analysis showed the potential cost savings in dental expenditures due to caries that can be achieved by only slightly increasing the consumption of SFG. The regular consumption of SFG cannot replace good dental hygiene like tooth brushing, but can have a significant impact on dental health, which can lead to increased cost savings for health care systems worldwide. (Am J Dent 2017;30:77-83).

 

 

 

 

Mail: Dr. Reinhard Rychlik, Institute of Empirical Health Economics, Am Ziegelfeld 28, D-51399 Burscheid, Germany. E-mail: reinhard.rychlik@ifeg.de

 

Effects of desensitizing agents for cervical dentin hypersensitivity:

A randomized clinical trial

 

Kyeong-Hwan Han, dmd, msc, Ju-Hee Hong, dh, msc, Joo-Hee Shin, dds, msc, phd, Jeong-Yol Lee, dmd, msc, phd

&  Sang Wan Shin, dds, mph, phd, msc

 

Abstract: Purpose: To evaluate the clinical efficacy of five commercially available desensitizing agents with different mechanisms applied to hypersensitive teeth. Methods: A randomized clinical trial was conducted on subjects suffering dentin hypersensitivity in Korea University Guro Hospital from October 2013 to April 2015. A total of 64 subjects met the selection criteria and were randomly assigned to five commercially available desensitizing agents, and applied according to the manufacturers’ instructions. Before and after application of desensitizing agents, subjects were evaluated with the Visual Analogue Scale (VAS) at baseline, 1 week, 1 month and 3 months. The difference between the degree of reduction of hypersensitivity in relation to time were evaluated with the repeated-measures ANOVA (P< 0.05). Results: Practitioner and subject-measured VAS values at 1 week, 1 month and 3 months showed a significant difference in all products compared with the first visit. On the other hand, no statistically significant differences between the products was shown. Desensitizing agents used in this clinical trial relieved dentin hypersensitivity up to 3 months. (Am J Dent 2017;30:84-88).

 

 

 

 

Mail: Dr. Sang Wan Shin, Department of Prosthodontics, Institute for Clinical Dental Research, Korea University Medical Center, Korea University, 97, Guro-Dong, Guro-Ku, Seoul, Korea, 152-703. E-mail: swshin@korea.ac.kr

 

 

 

Antibiotic prophylaxis for preventing dental implant failure and postoperative infection: A systematic review of randomized controlled trials

 

Zhuogeng Chen, dds, msc, Donghui Chen, dds, msc, Shangwei Zhang, dds, msc, Li Tang, dds, phd  &  Qiuying Li, dds, msc

 

Abstract: Purpose: To investigate whether prophylactic antibiotics are beneficial on patients undergoing routine dental implant placement procedures and to investigate which administration regimen is the most effective. Methods: The primary outcome was implant failure; the secondary outcome was postoperative infection. In the fixed-effects model, the Mantel-Haenszel method was used to calculate pooled relative risks (RRs) at 95% confidence intervals (CIs). To determine the outcomes, the quality of available evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE). Results: Prophylactic antibiotics significantly decreased the incidence of implant failure (RR, 0.29; 95% CI, 0.15-0.55; P= 0.0002; I²= 0%) but did not decrease infection. There was no statistically significant difference between single preoperative antibiotics (SPA) and preoperative and postoperative antibiotics (PPA) while treating patients with dental implant failure (RR, 1.07; 95% CI, 0.31-3.62; P= 0.92). No statistically significant difference was observed between SPA and PPA when prescribed to treat infection postoperatively (RR, 1.05; 95% CI, 0.29-3.85; P= 0.94; I²= 0%). (Am J Dent 2017;30:89-95).

 

 

 

Mail: Dr. Li Tang, Department of Implant Dentistry, Stomatology Hospital, Guangxi Medical University, 10 Shuangyong Road, Nanning, Guangxi 530021, China. E-mail: gxtangli@163.com

 

 

 

 

 

 

Effect of different concentrations and application times

of proanthocyanidin gels on dentin erosion

 

Ana Paula Boteon, dds, Anuradha Prakki, dds, ms, phd, Marília Afonso Rabelo Buzalaf, dds, ms, phd,

Daniela Rios, dds, ms, phd  &  Heitor Marques Honório, dds, ms, phd

 

Abstract: Purpose: To analyze the effect of different concentrations and application times of proanthocyanidin gels on dentin before an erosive challenge in order to evaluate if there is a dose-response or application time-response relationship in the use of these gels for erosion prevention. Methods: 80 bovine root dentin blocks were randomly and equally divided into 10 groups and treated according to the two factors under study (purified grape seed proanthocyanidin gel concentration and time of application): 0.05P1: 0.05% proanthocyanidin gel during 1 minute; 0.05P5: 0.05% proanthocyanidin gel during 5 minutes; 1P1: 1% proanthocyanidin gel during 1 minute; 1P5: 1% proanthocyanidin gel during 5 minutes; 5P1: 5% proanthocyanidin gel during 1 minute; 5P5: 5% proantho-cyanidin gel during 5 minutes; 10P1: 10% proanthocyanidin gel during 1 minute; 10P5: 10% proanthocyanidin gel during 5 minutes; Control 1: placebo gel during 1 minute; and Control 5: placebo gel during 5 minutes. The gels were applied over dentin blocks once before the first erosive challenge. After that, the blocks were subjected to three erosive cycles per day, during 5 days. Profilometry was used to quantify the dentin loss (µm). Data were analyzed by two-way ANOVA and Fisher's test (P< 0.05). Results: Statistical analysis showed that there was no significant difference between the application times. The different concentrations of proanthocianidin gels presented similar results (P> 0.05). All tested gels resulted in significantly less wear when compared to the placebo gel. (Am J Dent 2017;30:96-100).

 

 

 

 

 

 

Mail: Prof. Heitor Marques Honório, Department of Pediatric Dentistry, Orthodontics and Public Health, Bauru School of Dentistry, University of São Paulo (FOB-USP), Alameda Octávio Pinheiro Brisola, 9-75, Vila Universitária, 17012-901, Bauru, SP, Brazil.  E-mail: heitorhonorio@usp.br

 

 

Antimicrobial action and long-term effect of overnight denture cleansers

 

Amanda Peracini, dds, msc, phd, Ingrid Machado Andrade, dds, msc, phd, Viviane Cristina Oliveira, msc,

Ana Paula Macedo, msc, phd, Claudia Helena Silva-Lovato, dds, msc, phd, Valéria Oliveira Pagnano, dds, msc, phd, Evandro Watanabe, msc, phd  &  Helena de Freitas Oliveira Paranhos, dds, msc, phd,

 

Abstract: Purpose: To evaluate two denture cleansers for overnight soaking (0.5% sodium hypochlorite and peroxide alkaline) regarding efficacy against Candida spp. biofilms (randomized clinical trial) and their effects on the physical properties of a denture base acrylic resin simulating a period of 5 years of use (laboratory study). The Candida spp. were identified and their resistance to main antifungal agents was evaluated. Methods: 32 complete denture wearers were instructed to brush their dentures three times a day and to soak them (≥ 8 hours) in: control – water (C); alkaline peroxide (AP); or  0.5% sodium hypochlorite (SH). According to a randomized sequence, each solution was used for three alternate periods of 7 days. The antimicrobial action was performed by counting the colony forming units (CFU) of Candida spp. For collection of the biofilm, each upper complete denture was placed in a Petri dish, the internal surface was brushed (Tek brush) with saline solution for 2 minutes and the suspension was transferred to a test tube. After dilutions (10⁰ to 10^-3), aliquots of 50 µL were seeded inside Petri dishes containing Candida Chromagar. After incubation, the colonies were counted and the values of CFU/mL calculated. Data were transformed in log¹⁰ (CFU +1) and analyzed by the Friedman test (α= 0.05) followed by Wilcoxon and Bonferroni tests (α= 0.05). Each of the different species identified perfunctorily has been confirmed through the identification of yeasts kit. The resistance to antifungal agents (amphotericin B, nystatin, flucytosine, econazole, ketoconazole, miconazole and fluconazole) was also evaluated. Adverse effects were estimated on heat-polymerized resin specimens, simulating a 5-year period of overnight use. Acrylic resin specimens were randomly distributed into three groups: C: Control (distilled water), AP: alkaline peroxide; and SH: 0.5% sodium hypochlorite. Color change, surface roughness and flexural strength were evaluated at baseline and after immersion procedures. Data were compared by Kruskall-Wallis followed by Dunn’s test (color change and surface roughness) and one-way ANOVA (flexural strength) (α= 0.05). Results: There was a reduction of Candida spp. counts after using both solutions (AP and SH). The Candida spp. most often isolated was C. albicans, followed by the C. glabrata. Only 24.7% of isolate strains were resistant to at least one of the tested antifungals, highlighting azole compounds. Immersion in AP [5.73 (5.45-5.91)] caused significantly higher color change, with lower ΔE values for C [1.12 (1.15-1.37)] followed by SH [3.70 (3.51-3.98)]. The NBS values were classified as “slight” for C (1.12) group and “considerable” for AP (5.27) and SH (3.40). No solution altered surface roughness significantly. Flexural strength (in MPa) was significantly lower for C (64.59), AP (63.96 ± 12.98) and SH (62.84 ± 8.62) when compared to a group without any immersion (109.12 ± 8.37). (Am J Dent 2017:30:101-108).

 

 

Mail: Dr. Helena de Freitas Oliveira Paranhos, Department of Dental Materials and Prosthodontics, Ribeirão Preto Dental School, University of São Paulo, Avenida do Café S/N, Ribeirão Preto, SP, CEP: 14040-904, Brazil. E-mail: helenpar@forp.usp.br

 

 

Comparison of nanofluoridated hydroxyapatite of varying fluoride content

for dentin tubule occlusion

 

Qinghua Yu, ms, Hongyan Liu, phd, Zhiguo Liu, phd, Yan Peng, PhD, Xiaoning Cheng, ms, Ke Ma, ms & Yakun Ji, ms

 

Abstract: Purpose: To evaluate the viability of a series of nano-fluoridated hydroxyapatite (nano-FHA) formulations of varying fluoride content for the occlusion of exposed dentin tubules, in comparison to nano-hydroxyapatite (nano-HA). Methods: Nano-FHA powders with varying levels of fluoride ion were synthesized to substitute hydroxyl ions (^–OH) present in hydroxyapatite (HA). Nano-FHA were defined as 2nFHA,4nFHA,6nFHA, 8nFHA and 10nFHA, with the molar ratio of F^- to Ca₂+ of 0.002,0.004,0.006,0.008 and 0.01, respectively. The powders were synthesized using a wet chemistry route, and characterized by transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The methylthiazol tetrazolium (MTT) assay was used to assess cell viability toward nano-FHA. According to the content of F^-, the nano-nFHA and nano-HA powders were divided into six groups, with the artificial saliva as control. They were spread over the dentin surface for 1 minute and repeated three times per day for 7 consecutive days. After washing and brushing with distilled water for an additional 7 days, scanning electron microscopy was used to evaluate the in vitro plugging rate of the tubules and penetrating depth. Results: The 2nFHA, 4nFHA, 6nFHA, 8nFHA and 10nFHA powders were prepared and characterized. The 8nFHA had less crystallinity compared to 2nFHA,4nFHA, and 6nFHA.The MTT assay (from 12 to 120 hours) showed that the cell viability of the L-929 fibroblasts in the 2nFHA, 4nFHA, 6nFHA, 8nFHA, 10nFHA, and nano-HA groups ranged from 80.54 ± 3.35% to 112.9 ± 4.8%. Most of the nano-FHA powders successfully occluded dentin tubules. The plugging rate of 8nFHA was significantly higher than that of the 2nFHA, 4nFHA, 6nFHA and nano-HA groups. The penetrating depth of the 8nFHA group into the tubules was also significantly higher than that of the other nano-FHA and nano-HA group. (Am J Dent 2017;30:109-115).

 

 

 

Mail: Prof. Qinghua Yu, Department of Operative Dentistry and Endodontics, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou 510055, P. R. China. E-mail: yuqinghua1966@126.com