^{December 2015 Abstracts}

Surface properties of resin-based composite materials and biofilm formation: A review of the current literature

 

Gloria Cazzaniga, dds, Marco Ottobelli, dds, Andrei Ionescu, dds, phd, Franklin Garcia-Godoy, dds, ms, phd, phd  &  Eugenio Brambilla, dds

 

Abstract: Purpose: To evaluate the state of art on the relations between surface properties (surface roughness, topography, surface free energy and chemistry) of resin-based composite materials and microbial adhesion and biofilm formation. Methods: An electronic search using Scopus and PubMed (until May 2015) was conducted applying the following search items: “Plaque OR Biofilm AND Surface chemistry”, “Plaque OR Biofilm AND Surface-free energy”, “Plaque OR Biofilm AND Roughness”, “Surface characteristics AND Composites”, “Biofilm AND Surface characteristics”. Results: Surface properties of resin-based composite materials as well as surface treatments can strongly affect bacterial adhesion and biofilm formation, although the “ideal” surface features have not been identified yet. Moreover, investigations highlighted that cariogenic biofilm formation may alter materials’ surface properties, thus encouraging bacterial adhesion and biofilm formation, starting a “vicious cycle” which might compromise restoration longevity. (Am J Dent 2015;28:311-320).

 

 

 

 

Mail: Dr. Gloria Cazzaniga, I.R.C.C.S. Galeazzi Institute, Department of Biomedical, Surgical and Dental Sciences, University of Milan, Via Pascal 36, Milan, Italy.  E-mail: gloria.cazzaniga@yahoo.it

 

Adhesive sealing of dentin surfaces in vitro: A review

 

Manar M. Abu Nawareg, bds, msc, phd, Ahmed Z. Zidan, bds, msc, phd, Jianfeng Zhou, dds, phd, Ayaka Chiba, bds, Jungi Tagami, dds, phd  &  David H. Pashley, dmd, phd

 

Abstract: Purpose: This review describes the evolution of the use of dental adhesives to form a tight seal of freshly prepared dentin to protect the pulp from bacterial products, during the time between crown preparation and final cementation of full crowns. The evolution of these “immediate dentin sealants” follows the evolution of dental adhesives, in general. That is, they began with multiple-step, etch-and-rinse adhesives, and then switched to the use of simplified adhesives. Methods: Literature was reviewed for evidence that bacteria or bacterial products diffusing across dentin can irritate pulpal tissues before and after smear layer removal. Smear layers can be solubilized by plaque organisms within 7-10 days if they are directly exposed to oral fluids. It is likely that smear layers covered by temporary restorations may last more than 1 month. As long as smear layers remain in place, they can partially seal dentin. Thus, many in vitro studies evaluating the sealing ability of adhesive resins use smear layer-covered dentin as a reference condition.  Surprisingly, many adhesives do not seal dentin as well as do smear layers. Results: Both in vitro and in vivo studies show that resin-covered dentin allows dentin fluid to cross polymerized resins. The use of simplified single bottle adhesives to seal dentin was a step backwards. Currently, most authorities use either 3-step adhesives such as Scotchbond Multi-Purpose or OptiBond FL or two-step self-etching primer adhesives, such as Clearfil SE, Unifil Bond or AdheSE. (Am J Dent 2015;28:321-332).

 

 

Mail: Dr. David H. Pashley, Department of Oral Biology, College of Dental Medicine, Georgia Regents University, Augusta, GA, 30912, USA. E-mail: dpashley@gru.edu

 

Dentin wear after simulated toothbrushing with water, a liquid dentifrice or a standard toothpaste

 

Youngjune  Jang, dds,  Jung-Joon  Ihm, phd,  Su-Jin  Baik,  Kyung-Jin  Yoo,  Da-Hyun  Jang, Byoung-Duck  Roh, dds, msd, phd  &  Deog-Gyu  Seo, dds, msd, phd

 

Abstract: Purpose: To investigate the influence of dentifrices with and without abrasives on the wear and surface topography of human dentin following simulated toothbrushing in vitro. Methods: 24 dentin specimens were prepared and randomly allocated to a liquid dentifrice (Garglin Gum-Guard), conventional dentifrice (333 Clinic Total Care), and control (distilled water) groups. Specimens were subjected to simulated toothbrushing of 50,000 repeated strokes under a 150 g-load. The dentin surface was profiled in each specimen using a profilometer before and after toothbrushing. The mean surface roughness (Ra) of the specimens was calculated and compared by one-way ANOVA and Tukey's post-hoc test (α= 0.05). The dentin surfaces were further examined by scanning electron microscopy (SEM). Results: The Ra values were similar between the liquid dentifrice and control groups (P> 0.05), and was significantly higher in the conventional dentifrice group (P< 0.001). On SEM examination, patent dentin tubules were observed in the conventional dentifrice and liquid dentifrice groups, but were not observed in the control group. (Am J Dent 2015;28:333-336).

 

 

Mail: Dr. Deog-Gyu Seo, Department of Conservative Dentistry and Dental Research Institute, School of Dentistry, Seoul National University, 101 Daehak-ro, Jongno-gu, Seoul, Korea. E-mail: dgseo@snu.ac.kr

 

 

Evaluation of two disinfection/sterilization methods on silicon rubber-based composite finishing instruments

 

Vânia A. Lacerda, ms, Leandro O. Pereira, ms, Raphael  Hirata Junior, dds, ms, scd  &  Cesar R. Perez, dds, ms, scd

 

Abstract: Purpose: To evaluate the effectiveness of disinfection/sterilization methods and their effects on polishing capacity, micromorphology, and composition of two different composite finishing and polishing instruments. Methods: Two brands of finishing and polishing instruments (Jiffy and Optimize), were analyzed. For the antimicrobial test, 60 points (30 of each brand) were used for polishing composite restorations and submitted to three different groups of disinfection/sterilization methods: none (control), autoclaving, and immersion in peracetic acid for 60 minutes. The in vitro tests were performed to evaluate the polishing performance on resin composite disks (Amelogen) using a 3D scanner (Talyscan) and to evaluate the effects on the points’ surface composition (XRF) and micromorphology (MEV) after completing a polishing and sterilizing routine five times. Results: Both sterilization/disinfection methods were efficient against oral cultivable organisms and no deleterious modification was observed to point surface. (Am J Dent 2015;28:337-341).

 

 

Mail: Dr. Cesar R. Perez, R. São Francisco Xavier, 524 Maracanã, Rio de Janeiro, RJ, CEP 20550-900, Brazil. E-mail: cesarperez@superig.com.br

 

 

Efficacy of different “in-office” desensitizing treatment methods: An in vitro SEM analysis

 

Renata  De  Cássia  Gomes  Camacho, dds,  Giovana  Lecio  Miranda, dds,  Fábio  Tonasso  Oliveira, Fernanda  Vieira  Ribeiro, dds, msc, phd,  Suzana  Peres  Pimentel, dds, msc, phd &  Renato  Corrêa  Viana  Casarin, dds, msc, phd

 

Abstract: Purpose: To evaluate, in vitro, the obliteration of dentin tubules promoted by different desensitizing methods, before and after pH cycling. Methods: Human dentin blocks of 4×4 mm were randomly divided into: control group (n= 20): no treatment; Group GH (n= 20): surface treatment with a solution containing glutaraldehyde (5.1%), HEMA (36.1%), sodium fluoride (NaF), and deionized water; Group NP (n= 20): surface treatment with a calcium phosphate gel containing nanostructured hydroxyapatite crystals, NaF and NK; and Group ARG (n=20): surface treatment with a paste containing CaCO₃ and 8% arginine. After treatment, 10 samples of each group were evaluated in scanning electron microscopy (SEM) while another 10 were included in a pH cycling procedure for 48 hours, and then analyzed in the SEM. All SEM images were evaluated by three calibrated examiners regarding dentin tubular obliteration. Mann-Whitney and Kruskal-Wallis tests were used for data analysis (P< 0.05). Results: The GH, NP, and ARG groups promoted immediate obliteration higher than the control group (P< 0.05) with NP and ARG groups superior to GH group (P< 0.05). After pH cycling, an increase in tubular obliteration in the GH group was observed, which was similar to the NP and ARG groups (P> 0.05), even though all groups promoted higher obliteration than the control group (P< 0.05). All treatments were effective in a tubular obliteration. (Am J Dent 2015;28:342-346).

 

 

Mail: Dr. Suzana Peres Pimentel, 212 Bacelar Ave., Vila Clementino, São Paulo, SP, 14560-023, Brazil. E-mail: suppimentel@yahoo.com

 

Effect of sonic vibration of an ultrasonic toothbrush on the removal of Streptococcus mutans biofilm from enamel surface

 

Lina Naomi  Hashizume, dds, phd  &  Alessandra  Dariva, dds

 

Abstract: Purpose: To evaluate in vitro the effect of sonic vibration of an ultrasonic toothbrush in the removal of Streptococcus mutans (S. mutans) biofilm from human enamel. Methods: S. mutans dental biofilm was formed in vitro on human enamel blocks coated by salivary pellicle. The blocks were incubated with a suspension of S. mutans at 37ºC for 24 or 72 hours. The blocks were divided to one of three conditions according to the different toothbrush action modes: ultrasound plus sonic vibration (U+SV), ultrasound-only (U) and no ultrasound and no sonic vibration (control). Samples were exposed to each mode for 3 minutes with the toothbrush bristles placed 5 mm away from the enamel block surface. The samples were observed by scanning electron microscopy (SEM) and quantification of S. mutans was performed. Results: U+SV showed lower bacterial counts compared to U and control on the 72 hour-biofilm (P< 0.05). The SEM analysis revealed that U+SV and U disrupted the S. mutans chains in the 24- and 72-hour biofilm. (Am J Dent 2015;28:347-350).

 

 

Mail: Dr. Lina Naomi Hashizume, Department of Preventive and Social Dentistry, Faculty of Dentistry, Federal University of Rio Grande do Sul, Rua Ramiro Barcelos, 2492, Santana, Porto Alegre, RS, CEP 90035-003, Brazil.  E-mail: lhashizume@yahoo.com

 

 

Randomized controlled trial comparing a powered toothbrush with distinct multi-directional cleaning action to a manual flat trim toothbrush

 

John Gallob, dmd,  Luis  R. Mateo, ma,  Patricia Chaknis, bs,  Boyce M. Morrison, Jr, phd

&  Fotinos Panagakos, dmd, phd

 

Abstract: Purpose: To compare the plaque and gingivitis efficacy of a power toothbrush with distinct multi-directional cleaning action (Colgate® ProClinical® A1500 Power Toothbrush) against a manual flat-trim toothbrush (Oral-B Indicator). Methods: This randomized control trial was a single-center, examiner-blind, parallel-group, design and assessed plaque removal after a single brushing, as well as plaque removal and gingivitis reduction after 4 weeks and 12 weeks of brushing. Qualifying subjects used their assigned toothbrush to brush their teeth under supervision after which they were evaluated for plaque (post-brushing). Over the next 12 weeks, subjects brushed unsupervised at home with their assigned toothbrush. After 4 weeks and 12 weeks, subjects returned to the center for plaque and gingivitis examinations. Results: 80 subjects were screened for eligibility and randomized into the study. 79 subjects completed the study. Both toothbrushes provided statistically significant reductions in all plaque index scores at all time points in comparison to the pre-brushing scores. After 4 weeks and 12 weeks, statistically significant reductions in gingivitis and gingivitis severity scores were observed for subjects using the power toothbrush, whereas statistically significant increases in gingivitis and gingivitis severity were observed for subjects using the manual toothbrush. In conclusion, relative to the manual toothbrush, the power toothbrush provided statistically significantly (P< 0.05) greater removal of plaque: whole-mouth (131%), gumline (97.4%), and interproximal (220%), as well as reductions in gingivitis (400%), and gingivitis severity (320%) after 12 weeks of use. Compared to the manual flat-trim toothbrush, the power toothbrush with distinct multi-directional cleaning action demonstrates statistically and clinically significantly greater levels of plaque removal and gingivitis reduction at all time points. (Am J Dent 2015;28:351-356).

 

 

Mail: Dr. Fotinos Panagakos, Colgate-Palmolive Technology Center, 909 River Road, Piscataway, NJ, 08854, USA. E-mail: foti_panagakos@colpal.com

 

Depth of cure of bulk fill composites with monowave and polywave curing lights

 

Timothy  S.  Menees, bs  Chee  Paul  Lin, phd,  Dave  D.  Kojic, dds, msc,  John  O.  Burgess, dds, ms &  Nathaniel  C.  Lawson, dmd, phd

 

Abstract: Purpose: To measure and compare the depth of cure (DOC) of two bulk fill resin composites using a monowave and polywave light curing unit (LCU) according to ISO 4049 and using custom tooth molds. Methods: The DOC of Tetric Evoceram Bulk Fill and Filtek Bulk Fill Posterior were measured using a monowave LED LCU (Elipar S10) and a polywave LED LCU (Bluephase G2). Metal molds were used to fabricate 10 mm long DOC specimens (n= 10) according to ISO 4049. Uncured composite material was scraped away with a plastic instrument and half the length of remaining composite was measured as the DOC. Custom tooth molds were fabricated by preparing >10 mm long square-shaped (4 x 4 mm) holes into the mesial/distal surfaces of extracted human molars. Resin composite was placed into one end of the prepared tooth and light polymerized. Uncured resin composite was removed from the opposite side from which the tooth was irradiated and the tooth was sectioned mesio-distally. Half the length of remaining cured composite was measured as the DOC.  Data were analyzed by three-way ANOVA (α= 0.05) for factors material, LCU, and mold. Results: The main effect LCU was not significant (P= 0.58). The interaction effect between material × mold was significant (P= 0.0001). The DOC of the composites differed significantly only with the stainless steel mold in which Tetric Evoceram Bulk Fill showed a deeper DOC than Filtek Bulk Fill Posterior (4.03 ± 0.14 vs 3.56 ± 0.38 mm, P< 0.0001). (Am J Dent 2015;28:357-361).

 

 

Mail:  Dr. Nathaniel C. Lawson, School of Dentistry, University of Alabama at Birmingham, SDB Box 49, 1720 2nd Ave S., Birmingham, AL 35294-0007, USA.  E-mail: nlawson@uab.edu

 

Two pre-treatments for bonding to non-carious cervical root dentin

 

Simon Flury, dds, Anne Peutzfeldt, dr odont, phd  &  Adrian Lussi, dds, dipl chem ing

 

Abstract: Purpose: To investigate the effect of airborne-particle abrasion or diamond bur preparation as pre-treatment steps of non-carious cervical root dentin regarding substance loss and bond strength. Methods: 45 dentin specimens produced from crowns of extracted human incisors by grinding the labial surfaces with silicon carbide papers (control) were treated with one of three adhesive systems (Group 1A-C; A: OptiBond FL, B: Clearfil SE Bond, or C: Scotchbond Universal; n= 15/adhesive system). Another 135 dentin specimens (n= 15/group) produced from the labial, non-carious cervical root part of extracted human incisors were treated with one of the adhesive systems after either no pre-treatment (Group 2A-C), pre-treatment with airborne-particle abrasion (CoJet Prep and 50 µm aluminum oxide powder; Group 3A-C), or pre-treatment with diamond bur preparation (40 µm grit size; Group 4A-C). Substance loss caused by the pre-treatment was measured in Groups 3 and 4. After treatment with the adhesive systems, resin composite was applied and all specimens were stored (37°C, 100% humidity, 24 hours) until measurement of micro-shear bond strength (µSBS). Data were analyzed with a nonparametric ANOVA followed by Kruskal-Wallis and Wilcoxon rank sum tests (level of significance: α= 0.05). Results: Overall substance loss was significantly lower in Group 3 (median: 19 µm) than in Group 4 (median: 113 µm; P< 0.0001). There were no significant differences in µSBS between the adhesive systems (A-C) in Group 1, Group 3, and Group 4 (P≥ 0.133). In Group 2, OptiBond FL (Group 2A) and Clearfil SE Bond (Group 2B) yielded significantly higher µSBS than Scotchbond Universal (Group 2C; P≤ 0.032). For OptiBond FL and Clearfil SE Bond, there were no significant differences in µSBS between the ground crown dentin and the non-carious cervical root dentin regardless of any pre-treatment of the latter (both P= 0.661). For Scotchbond Universal, the µSBS to non-carious cervical root dentin without pre-treatment was significantly lower than to ground crown dentin and to non-carious cervical root dentin pre-treated with airborne-particle abrasion or diamond bur preparation (P≤ 0.014). (Am J Dent 2015;28:362-366).

 

 

Mail: Dr. Simon Flury, Department of Preventive, Restorative and Pediatric Dentistry, School of Dental Medicine, University of Bern, Freiburgstrasse 7, CH-3010 Bern, Switzerland. E-mail: simon.flury@zmk.unibe.ch

 

 

Influence of organic acids present in oral biofilm on the durability of the repair bond strength, sorption and solubility of resin composites

 

Stéphane da Silva, dds, ms, Eduardo Moreira da Silva, dds, msc, phd, Marcella Bruna Ferreira Delphim, Laiza Tatiana Poskus, dds, msc, phd  &  Cristiane Mariote Amaral, dds, msc, phd

 

Abstract: Purpose: To evaluate the repair bond strength after storage in water, lactic and propionic acid after 7 days and 6 months and the sorption and solubility of resin composites used. Methods: Five cylinders of each resin composite (microhybrid, nanofilled and silorane-based composite) were prepared. Specimens were aged with thermocycling (5 and 55°C) 5,000 times. A repair procedure was performed using intraoral sandblasting with 50-µm aluminum oxide, application of an adhesive system and cylinder of composite was fabricated. Specimens were sectioned into beams and stored in three immersion media: water, propionic acid and lactic acid. The microtensile bond strength was measured after periods of 7 days and 6 months. Sorption and solubility were evaluated using 15 specimens (Ø= 6 mm; h= 1 mm) of each resin composite, which were prepared and assigned into three groups (n= 5) according to the immersion media (water, propionic acid and lactic acid). Data were analyzed using one-way/two-way/three-way ANOVA and Tukey’s test (α= 0.05). Results: The resin composites, immersion media and time of immersion did not affect the repair bond strength (microhybrid 38.3 to 40.9 MPa; nanofilled 38.7 to 42.2 MPa; silorane 41.2 to 51.1 MPa). Additionally, the immersion media did not affect the sorption and solubility. The silorane-based composite presented the lowest sorption (10.5 to 12.1µg/mm³) and solubility (-2.4 to -2.7 µg/mm³), while the nanofilled methacrylate-based composite showed the highest sorption (32.1 to 33.6 µg/mm³). Regarding solubility, the nanofilled and microhybrid methacrylate-based composites did not present statistically significant differences. (Am J Dent 2015;28:367-372).

 

 

Mail: Dr. Cristiane Mariote Amaral, School of Dentistry, Federal Fluminense University, Rua Mário Santos Braga, nº 30, Campus Valonguinho, Centro, Niterói, RJ, CEP 24020-140, Brazil.  E-mail: camaral@vm.uff.br