Rogério Goulart da Costa, dds, ms, Andrea Freire, dds, ms, phd, Eduardo Christiano Caregnatto de Morais, dds, ms, phd, Evelise Machado de Souza, dds, ms, phd, Gisele Maria Correr, dds, ms, phd & Rodrigo Nunes Rached, dds, ms, phd
Abstract: Purpose: To investigate the fracture resistance of weakened roots restored with prefabricated or CAD/ CAM-customized posts and cores as well as the thickness of the cement film and the presence of voids in the cement. Methods: The roots of 40 human premolars were weakened by removing internal dentin with a diamond bur (2.5 mm in the coronal third and 1.5 mm in the apical third) and restored with prefabricated posts (PPs) or customized posts (CPs) with or without a zirconia crown (n= 10). Posts and crowns were cemented with resin cement. Microtomography was used to determine the thickness of the cement film and whether voids were present. After fatigue testing (1 million cycles, 50 N, 5 Hz, 36.5ºC), the specimens underwent compression testing with an oblique load (30º, 1 mm/minute) and fracture strengths were recorded (N). Fracture strength and film thickness were analyzed with ANOVA and the Games-Howell test; the variable presence of voids was analyzed with the Mann-Whitney test (α= 5%). Results: Mean fracture strengths varied between 640.4 and 792.9 N and did not differ significantly between groups. The CP group had a thinner cement film and fewer voids than the PP group. There was a positive, statistically significant correlation (Spearman, R=0.488, P= 0.029) between these variables. (Am J Dent 2017;30:3-8).
Mail: Dr. Rodrigo Nunes Rached, PUCPR (Dentistry), Rua Imaculada Conceição, 1155, Curitiba, PR, Brazil, 80215-901. E-mail: firstname.lastname@example.org
Zeynep Bilge Kutuk, dds, phd, Sevil Gurgan, dds, phd, Reinhard Hickel, dds, phd & Nicoleta Ilie, dipl-eng, phd
Abstract: Purpose: To investigate in vitro the effect of extremely high irradiance light-emitting diode (LED) light curing units (LCU) with different exposure distances and curing modes on the micromechanical properties of a nano hybrid resin based composite. Methods: 72 resin based composite (RBC) (Kalore) specimens with 2 mm thickness were cured using two high irradiance LED LCUs (Bluephase 20i and FlashMax P3) at 0 and 7 mm exposure distances. The curing conditions were: a) Bluephase 20i – 10 seconds – High power; b) Bluephase 20i – 15 seconds – High power; c) Bluephase 20i – 5 seconds – Turbo; d) Bluephase 20i – 15 seconds – Soft start; e) FlashMax P3 – 4 mm tip cover – 3 seconds; f) FlashMax P3 – without tip cover – 3 seconds. The incident and transmitted irradiance and radiant exposure were evaluated in real time during curing, with a radiometer (MARC Resin Calibrator). The micromechanical properties (Vickers hardness, HV and indentation modulus, E) were measured with an automatic universal hardness indenter after storing specimens for 24 hours in distilled water. Data were analyzed with one- and two-way ANOVA tests followed by Tukey test and partial eta-square statistics (α= 0.05). Results: For both LCUs, incident irradiance decreased progressively with increased exposure distance, reaching at 7 mm exposure distance less than 50% of the value measured when the LCU was applied directly on specimen’s surface. In descending order of strength of their effects, the parameters incident irradiance (HV; ηP²=0.828, E; 0.693), LCU (HV, 0.257, E, 0.043) and exposure distance (HV, 0.031, E, 0.028) were significant factors affecting HV and E (P < 0.05). The localized radiant exposure (the incident and transmitted) as well as the position of HV and E measurements (top-bottom of the specimen) were additional factors affecting significantly only HV (P < 0.05), but not E (P > 0.05). (Am J Dent 2017;30:9-15).
Mail: Dr. Zeynep Bilge Kutuk, Department of Restorative Dentistry, Hacettepe University, School of Dentistry, Sihhiye, Ankara, 06100, Ankara, Turkey. E-mail: email@example.com
Inga Rullmann, dds, Michael Patyna, dds, Bram Janssen, dds, Brita Willershausen, dds, phd & Claus-Peter Ernst, dds, phd
Abstract: Purpose: To investigate the polymerization shrinkage stress of different low viscous bulk composites (SDR, Venus Bulk Fill, X-tra Base, Filtek Bulk Fill) in comparison to a conventional flowable composite (Filtek Supreme XTE Flow) and to high viscous bulk and conventional composites (Filtek Supreme XTE, GrandioSO, Tetric EvoCeram, Tetric EvoCeram BulkFill, Venus Diamond, Venus Pearl), as well as to an experimental composite (Ormocer) and a sonic-activated bulk fill composite (Sonicfill), by means of photoelastic investigation. Methods: To ensure bonding of the resin composite, cylindrical cavities (Ø 4mm) in araldite B epoxide resin plates (40 × 40 × 4 mm3) were pre-treated with the Rocatec system. Embedded in araldite plates, six resin composite specimens of each material were exposed for 60 seconds from one side (Translux Power Blue, 1,000 mW/cm2). The samples were stored, light-protected and dry (23°C). Polymerization shrinkage stress data (MPa) were calculated 15 minutes, 1 and 24 hours after light exposure, based on the diameter of the isochromatic curves of first order, obtained from araldite plates. Statistical analysis was performed with the Wilcoxon-test and Bonferroni correction (P< 0.0006). Results: After 15 minutes/1 hour, the mean polymerization stress values calculated were: for SDR 4.4 ± 0.1/4.4 ± 0.2 MPa; Venus Bulk Fill 4.8 ± 0.3/4.9 ± 0.3 MPa; X-tra Base 6.5 ± 0.3/6.7 ± 0.3 MPa; Filtek Bulk Fill 4.9 ± 0.3/4.9 ± 0.3 MPa; Filtek Supreme XTE Flow 8.0 ± 0.3/8.2 ± 0.2 MPa; Filtek Supreme XTE 7.1 ± 0.1/7.4 ± 0.2 MPa; GrandioSO 6.3 ± 0.4/6.3 ± 0.3 MPa; Tetric EvoCeram 4.5 ± 0.1/4.6 ± 0.1 MPa; Tetric EvoCeram BulkFill 4.9 ± 0.2/5.0 ± 0.3 MPa; Venus Diamond 3.7 ± 0.3/3.8 ± 0.3 MPa; Venus Pearl 3.9 ± 0.2/4.0 ± 0.2 MPa, Sonicfill 5.4 ± 0.2/5.6 ± 0.3 MPa; and Ormocer (experimental) 4.1 ± 0.2/4.3 ± 0.2 MPa. After 24 hours, the following mean stress values were obtained: SDR 4.7 ± 0.2 MPa; Venus Bulk Fill 5.1 ± 0.2 MPa; X-tra Base 7.2 ± 0.4 MPa; Filtek Bulk Fill 5.3 ± 0.3 MPa; Filtek Supreme XTE Flow 8.7 ± 0.3 MPa; Filtek Supreme XTE 7.9 ± 0.2 MPa; GrandioSO 7.0 ± 0.4 MPa; Tetric EvoCeram 4.9 ± 0.1 MPa; Tetric EvoCeram BulkFill 5.4 ± 0.3 MPa; Venus Diamond 4.5 ± 0.3 MPa; Venus Pearl 4.5 ± 0.3 MPa, Sonicfill 5.8 ± 0.2 MPa and Ormocer (experimental) 4.5 ± 0.2 MPa. The new and experimental resin composites showed significantly less polymerization shrinkage stress than the conventional resin composite (Filtek Supreme XTE). (Am J Dent 2017;30:16-22).
Mail: Michael Patyna, Department for Operative Dentistry, University Medical Center of the Johannes Gutenberg University Mainz, Augustusplatz 2, D-55131 Mainz, Germany. E-mail: firstname.lastname@example.org
Mansour Rismanchian, dds, ms, Saeid Nosouhian, dds, ms, Mohammad Shahabouee, dds, ms, Amin Davoudi, dds & Farzaneh Nourbakhshian, dds
Abstract: Purpose: To evaluate the antiseptic properties of five different disinfectant techniques on three different peri-implantitis (PI) associated biofilms. Methods: 90 implant titanium disks, with the same thickness and diameter, were prepared and randomly divided into 18 groups (n = 5) based on the microbiota strains (S. aureus, S. epidermidis and C. albicans) and using the following disinfectant techniques: soft laser therapy, photodynamic therapy (PDT), 0.12% NaOCl, 0.2% chlorhexidine, 3% H2O2, and control groups. After forming a protein layer on disk surfaces, the specimens were exposed to the microbial suspensions. After decontamination according to designated techniques, 2% Trypsin protease was administered to isolate the surviving microorganisms. Muller Hinton agar culture was used for microbiota growth. After 48-hour incubation, the standard colony forming unit (CFU) was assayed and the collected data were analyzed by Kruskal-Wallis and Mann-Whitney tests at a significance level of 0.05. Results: The highest amount of CFU/ml values was shown by C. albicans, which was subjected to PDT (25.12 ± 30.23). The least disinfecting efficacy on S. epidermidis was demonstrated by the laser group (all P-values ≤ 0.01). Nevertheless, all of the groups exhibited significant differences with the control groups (all P-values < 0.01). (Am J Dent 2017;30:23-26).
Mail: Dr. Saeid Nosouhian, Hezar Jarib St, Dental Implants Research Center, Isfahan University of Medical Sciences, Isfahan, Iran. E-mail: email@example.com
Claire Hall, msc, Farzana Sufi, msc, Nan Wang, phd & Chhaju Ram Goyal, bdsc
Abstract: Purpose: To evaluate the efficacy of an experimental mouthwash containing 3% potassium nitrate (KNO3) in relieving dentin hypersensitivity when used as an adjunct to brushing with fluoride toothpaste compared with use of the same toothpaste alone. Methods: This was one of three randomized, two-treatment, examiner-blind, parallel-design, single-site, 8-week studies in healthy subjects with self-reported and clinically diagnosed dentin hypersensitivity. Subjects were randomized to receive either fluoride toothpaste plus 3% KNO3 mouthwash or the same fluoride toothpaste alone, and instructed to use their allocated treatment twice daily for the next 8 weeks. Dentin hypersensitivity was evaluated at baseline and following 4 and 8 weeks of treatment through assessment of responses to evaporative (air) and tactile stimuli [measured by the Schiff Sensitivity Scale, a visual rating scale (VRS), and tactile threshold, respectively], and using the Dentin Hypersensitivity Experience Questionnaire (DHEQ; a validated quality-of-life instrument for dentin hyper-sensitivity). Results: A total of 216 subjects were randomized and 214 completed the study. Both treatment groups demonstrated statistically significant reductions from baseline for each clinical measure of sensitivity (P≤ 0.01) at Weeks 4 and 8. Use of the 3% KNO3 mouthwash after brushing with fluoride toothpaste resulted in statistically significantly greater reductions in sensitivity to an evaporative (air) stimulus (mean Schiff score and mean VRS, P< 0.001; primary objective mean Schiff score at Week 8, P< 0.0001) and statistically significantly higher tactile threshold (P< 0.001) at Weeks 4 and 8 compared with toothpaste alone. The DHEQ responses reflected the clinical outcomes for several parameters, indicating a significant improvement in oral health-related quality of life after 8 weeks’ use of the 3% KNO3 mouthwash. (Am J Dent 2017;30:27-34).
Mail: Farzana Sufi, Clinical Research (Oral Care), Research & Development, GSK Consumer Healthcare, St George’s Avenue, Weybridge, Surrey, KT13 0DE, UK. E-mail: firstname.lastname@example.org
Douglas Roberto Monteiro, phd, Laís Salomão Arias, msc, Renan Aparecido Fernandes, msc, Fabiana Gouveia Straioto, phd, Débora Barros Barbosa, phd, Juliano Pelim Pessan, phd & Alberto Carlos Botazzo Delbem, phd
Abstract: Purpose: To assess the effect of tyrosol on the production of hydrolytic enzymes (by Candida biofilm cells) and acid (by Streptococcus mutans biofilms), as well as to quantify single and mixed biofilms of these species formed on acrylic resin (AR) and hydroxyapatite (HA). Methods: Candida and S. mutans biofilms were formed on AR and HA in the presence of tyrosol during 48 hours. Next, acid proteinase, phospholipase and hemolytic activities of Candida biofilm cells were determined, while acid production by S. mutans biofilms was assessed by pH determination. The effect of tyrosol on mature biofilms (96 hours) was evaluated through quantification of total biomass, metabolic activity, number of colony-forming units and composition of biofilms’ extracellular matrix. Data were analyzed by one- and two-way ANOVA, followed by Tukey’s and Holm-Sidak’s tests (α = 0.05). Results: Treatments with tyrosol were not able to significantly reduce hydrolytic enzymes and acid production by Candida and S. mutans. Tyrosol only significantly reduced the metabolic activity of single biofilms of Candida species. (Am J Dent 2017;30:35-39).
Mail: Dr. Douglas Roberto Monteiro, Universidade do Oeste Paulista (UNOESTE), Dental School of Presidente Prudente, Department of Prosthodontics, Rua José Bongiovani 700, 19050-920 Presidente Prudente, SP, Brazil. E-mail: email@example.com
Gerhard Schmalz, dr med dent, Marion Müller, dr med dent, Jan Schmickler, dr med dent, Sven Rinke, dr med dent, msc, msc, Rainer Haak, dr med dent, mme, Rainer F. Mausberg, dr med dent & Dirk Ziebolz, dr med dent, msc
Abstract: Purpose: This randomized clinical study compared the influence of manual and power toothbrushes on clinical and microbiological findings in initial treatment of periodontitis. Methods: A total of 72 participants with a mean age of 55.7 years were randomly assigned to three groups (n= 24): oscillating-rotating (OR), sonic-active (SA) and manual toothbrush (MTB). At baseline, after 4 weeks and after 12 weeks, the following parameters were assessed: modified Quigley-Hein-Index (QHI), papilla bleeding index (PBI), periodontal pocket depth (PPD), bleeding on probing (BOP) and recession. For microbiological analysis (PCR) of 11 periodontal pathogenic bacteria, samples of sulcular fluid were taken from the deepest pockets. Statistical analysis was performed using ANOVA, with the level of significance set at α= 5%. Results: All clinical parameters: PBI, modified QHI, PPD, BOP and recession showed an improvement after 12 weeks compared to baseline, regardless of which toothbrush system was used. Regarding PBI, the SA group showed significantly greater improvement compared to OR and MTB (P< 0.01). In plaque removal (QHI) only OR was significantly more effective than MTB (P= 0.01). Periodontal parameters showed a significantly higher reduction of PPD for SA compared to MTB and MTB compared to OR (P< 0.05), while for BOP only a significantly higher reduction in SA compared to OR was detected (P= 0.01) Microbiological analysis showed an improvement in prevalence of several bacteria without significant differences between groups. (Am J Dent 2017;30:40-46).
Mail: PD Dr. Dirk Ziebolz, M.Sc., Dept. of Cariology, Endodontology and Periodontology, University Medical Center Leipzig, Liebigstr. 10-14, D 04103 Leipzig, Germany. E-mail: firstname.lastname@example.org
Shahad Abudawood, bds, ms & Kevin J. Donly, dds, ms
Abstract: Purpose: To measure the amount of fluoride release and re-release after re-charge from two commonly used esthetic restorative materials and compare it to a new experimental material. Methods: 30 standardized disc-shaped specimens were fabricated using resin-based composite (Z100), resin-modified glass-ionomer cement (Vitremer) and a new experimental material which is a self-curing resin-based composite with light curing option. 10 specimens were made from each material. The specimens of each group were immersed separately in 10 ml distilled water. Fluoride release was measured after 1, 7, 14 and 30 days using a fluoride-specific ion electrode and an ion-analyzer. The specimens were then exposed to 2.0% neutral sodium fluoride foam (0.9% fluoride ion). The amount of fluoride re-released was measured at Days 1, 7, 14 and 30. Results: An ANOVA indicated a statically significant variance among the groups (P< 0.001). The experimental group demonstrated significantly less fluoride release at Day 1 compared to Day 31 (first day after 2% sodium fluoride application). At Days 7, 14 and 30 there was significantly more fluoride release than Day 7, 14 and 30 after the topical fluoride application (P< 0.001). There was significantly more fluoride release from Vitremer than the experimental material at Days 1 and 7. However, similar release was observed at Days 14 and 30 for Vitremer and experimental material, but not for Z100. Both Vitremer and the experimental material showed significantly more release of fluoride compared to Z100 at all time points. (Am J Dent 2017;30:47-51).
Mail: Ms. Shahad Abudawood, 8210 Floyd Curl Drive MSc 8118, San Antonio, TX 78229-3900, USA. E-mail: Abudawood@livemail.uthscsa.edu
Tianshuang Liu, dds, ms, Linfeng Wu, ms, phd, Jegdish P. Babu, ms, msc, phd, Timothy
L. Hottel, dds, ms, mba,
Abstract: Purpose: To evaluate the bactericidal effects of atmospheric non-thermal argon/oxygen plasma on in vitro oral biofilms constructed from S. mutans and/or S. sanguinis, and the influence of the plasma on the virulence properties of A. oris. Methods: In vitro oral biofilms were constructed in the wells of 48-well plates from S. mutans and/or S. sanguinis. The wells containing constructed biofilms and various amounts of phosphate-buffered saline (PBS) were treated with non-thermal argon/oxygen plasma brush for 2 minutes. The methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay and Live/Dead assay were used to evaluate the viability of biofilms in those wells after the plasma treatments. Meanwhile, A. oris suspensions were treated with the plasma and then evaluated for their virulence properties by measuring the hydrophobicity and co-aggregation capability of treated A. oris. Results: The MTT assay showed that exposure to non-thermal plasma for 2 minutes significantly reduced the viability of bacteria in both single-species and two-species biofilms of S. mutans and S. sanguinis with the reductions of up to 99%. Meanwhile, plasma treatment also altered the hydrophobicity of A. oris, and reduced their capability to co-aggregate with S. sanguinis. (Am J Dent 2017;30:52-56).
Mail: Dr. Liang Hong, College of Dentistry, University of Tennessee Health Science Center, 875 Union Avenue, Memphis, TN 38163, USA. E-mail: email@example.com