Suzana Beatriz Portugal de FÚcio, dds, ms, phd, AndrÉia Bolzan de Paula, dds, ms, phd, FabÍola Galbiatti de Carvalho, dds, ms, phd, Victor Pinheiro Feitosa, dds, ms Glaucia Maria B. Ambrosano, dds, ms, phd  &  Regina Maria Puppin-Rontani, dds, ms, phd

Abstract: Purpose: To evaluate in the laboratory the roughness (Ra) and micromorphology surface of the nanofilled resin-modified glass-ionomer (Ketac N100) subjected to biomechanical degradation, compared to Vitremer, Ketac Molar Easymix and Fuji IX. Methods: Specimens obtained from the ionomers were divided into two storage groups (n=10): relative humidity and S. mutans biofilm (biodegradation). After 7 days, Ra values and micrographs were obtained. Then, the brushing abrasion test (mechanical degradation) was conducted with dentifrice slurry (three-body) and the specimens were reassessed. Data were submitted to repeated measures three-way ANOVA and Tukey tests (P< 0.05). Results: There was significant interaction among the factors: material, storage and abrasion (before/after). Vitremer showed similar Ra values between storage groups, while the other materials presented higher Ra values after biodegradation test. Concerning biomechanical challenge, Ketac N100 presented the lowest Ra values. Ketac Molar Easymix and Fuji IX presented undesirable roughening of their surfaces under the detrimental conditions tested. The eroded aspect after biodegradation with filler exposure after mechanical degradation was evident. (Am J Dent 2012;25:315-320).

Mail: Prof. Regina M. Puppin-Rontani, Department of Pediatric Dentistry, FOP/UNICAMP, Av. Limeira, 901, Piracicaba - 13414-900 - SP, Brazil. E-mail: rmpuppin@fop.unicamp.br

TEM morphological characterization of a one-step self-etching system applied clinically to human caries-affected dentin and deep sound dentin

Egle  Milia, dds  mS,,  Roberto  Pinna, md, phd  ,  Giorgio  Castelli, md, Antonella  Bortone, md, phd, Salvatore  Marceddu,  Franklin  Garcia-Godoy, dds, ms, phd  &  Giuseppe  Gallina, mS, dds

Abstract: Purpose: To examine morphologically the hybrid layer of one-step self-etching adhesive, Clearfil S³ Bond (S³bond), in caries-affected dentin (CAD) and deep sound dentin (DSD) cavities performed clinically. For comparative group, a two-step self etching adhesive, Clearfil Protect Bond (Pbond) was used in a similar clinical situation. Methods: This study was carried out on carious and sound teeth clinically selected for extraction. In carious teeth, CAD was obtained by way of subjective criteria by removing infected tissue to form a cavity bottom. DSD was obtained at a depth of 4 mm in the dentin cavity of sound teeth. S³bond and Pbond were applied in the CAD and DSD cavities as indicated by the manufacturer, followed by a composite restoration. Teeth were extracted about 20 minutes after the bonding procedure, and processed for TEM analysis. Results: Expression of S³bond in CAD was morphologically highly variable. When affected tubules were occluded by intratubular mineralized deposits, the interface displayed a dense poly-HEMA hydrogel as water sorption by the hydrophilic S³bond toward the porous affected collagen. Conversely, when tubules appeared empty, voids of various sizes were formed by tubular fluid shift. In DSD, S³bond clearly exhibited voids and water channels as signs of the high permeability of the sub-surface. Although porosities were somewhat retained, Pbond expression showed a hermetic character which was independent of the dentin substrate. (Am J Dent 2012:25:000-000).

Mail: Prof. Egle Milia, Viale San Pietro 43/c, 07100Sassari, Italy. E-mail: emilia@uniss.it

Use of a new, simple, laboratory method for screening the antimicrobial and antiviral properties of hand sanitizers

Babak Baban, phd,  Jun Yao Liu, bs,  Franklin R. Tay, bdsc (hons), phd  &   David H. Pashley, dmd, phd

Abstract: Purpose: To develop a simple, laboratory method for screening the antimicrobial/antiviral activity of hand sanitizers, to replace the more time consuming use of human volunteers. Methods: A Rapid Agar Plate Assay (RAPA) was developed that uses sterile agar plates to simulate skin surfaces. After treating the agar plates with putative hand sanitizers, the plates were inoculated with gram-positive S. aureus or gram-negative E. coli. Untreated agar plates served as controls. After incubation for 48 hours, the bacteria were recovered and stained with fluorescent dyes. The number of live/dead bacteria was quantitated by flow cytometry. For anti-viral activity, mammalian cell lines were grown to confluency and infected with noroviruses (murine norovirus or feline calicivirus), and the number of dead cells was quantitated as the log₁₀ of number of cells killed. A liquid hand soap without any antibacterial activity (LHS) was used as the control. A popular ethanol-based hand sanitizer (GHS) was compared to a new quaternary ammonium-containing bactericidal hand cream (ABC). Results: The liquid soap was not effective against either gram-positive or gram-negative bacteria, or viruses. Both GHS and ABC were very effective against S. aureus, but much less so against E. coli. Both GHS and ABC were even more effective against the two noroviruses that cause gastrointestinal diseases, than they were against gram-positive bacteria. These results support the use of RAPA as an effective laboratory screening test to evaluate the antibacterial/antiviral activity of hand sanitizers or other antimicrobial products. (Am J Dent 2012;25:327-331).

Mail: Dr. David H. Pashley, Department of Oral Biology, College of Dental Medicine, Georgia Health Sciences University, 1120 15th Street, CL-2112, Augusta, GA 30912-1129, USA. E-mail: dpashley@georgiahealth.edu

Effects of water flow on ablation rate and morphological changes in human enamel and dentin after Er:YAG laser irradiation

Vivian Colucci, dds, ms, phd, FlÁvia Lucisano Botelho do Amaral, dds, ms, phd, Jesus Djalma PÈcora, dds, ms, phd, Regina Guenka Palma-Dibb, dds, ms, phd &  Silmara Aparecida Milori Corona, dds, ms, phd

Abstract: Purpose: To investigate the laboratory effect of Er:YAG laser on ablation rate and morphological changes in human enamel and dentin with varying water flow. Methods: 23 human third molars were sectioned in mesio-distal and buccal-lingual directions. The slabs were flattened and weighted on an analytical laboratory balance (control). A 4-mm² area was demarcated and the samples were randomly assigned into three groups according to water flow employed during the laser irradiation (1.0, 1.5, and 2.0 mL/minute). An Er:YAG laser was used to ablate enamel (80.22-J/cm², 300 mJ/4Hz) and dentin (96.26-J/cm², 250 mJ/4Hz). After irradiation, the samples were immersed in distilled water for 1 hour and then weighted again. The final mass was obtained and laser-irradiated substrate mass loss was calculated by the difference between the initial and final mass. Afterwards, specimens were prepared for SEM. Results: Data were submitted to ANOVA and Tukey’s test (P< 0.05). It was observed that the 2.0 mL/minute resulted in a higher mass loss, 1.0 mL/minute showed a lower mass loss, and 1.5 mL/minute demonstrated intermediate results (P< 0.05). The increase of water flow promoted less melting areas and cracks. Furthermore, dentin was more ablated than enamel. It may be concluded that the water flow of Er:YAG laser and the substrates affected the ablation rate. Among the tested parameters, 2.0 mL/minute improved the ability of ablation in enamel and dentin, with less morphologic surface alteration. (Am J Dent 2012;25:332-336).

Mail: Dr. Silmara Aparecida Milori Corona, Department of Operative Dentistry, Ribeirão Preto School of Dentistry, University of São Paulo (USP), Av. do Café, S/N, Monte Alegre, CEP: 14040-904, Ribeirão Preto - SP, Brazil. E-mail: silmaracorona@forp.usp.br

Antibacterial dental restorative materials: A state-of-the-art review 

Liang  Chen, phd,  Hong Shen, phd  &  Byoung  In  Suh, phd

Abstract: This review presents an updated knowledge on the antibacterial dental restorative materials and their performance clinically and in the laboratory. A search of English peer-reviewed dental literature over the last 30 years from PubMed and MEDLINE databases was conducted, and the key words included antibacterial, antimicrobial, dental, primer, adhesive, bonding agent, cement, and composite. Titles and abstracts of the articles listed from search results were reviewed and evaluated for relevancy. In summary, the incorporation of an appropriate amount of antibacterial agent provided dental restorative materials (dental bonding agents, resin composites, resin cements, glass-ionomer cements) antibacterial activity without significantly influencing mechanical properties. (Am J Dent 2012;25:337-346).

Mail:  Dr. Liang Chen, Bisco, Inc., 1100 W Irving Park Road, Schaumburg, IL 60193, USA.  E-mail: lchen@bisco.com

Anti-demineralization effect of a novel fluoride-releasing varnish on dentin

Toru Shiiya, dds, phd,  Yoshiharu Mukai, dds, phd,  Kiyoshi Tomiyama, dds, phd  &  Toshio Teranaka, dds, phd

Abstract: Purpose: To investigate the laboratory anti-demineralization effect of a novel fluoride-releasing varnish containing surface reaction-type prereacted glass-ionomer (S-PRG) filler. Methods: Paired specimens were cut from bovine root dentin. One of each pair was used for the S-PRG group, and the other served as a control (n= 6). A 1×3 mm test surface was made on each specimen with the fluoride-releasing varnish. The novel fluoride-releasing varnish is categorized as a two-bottle-type self-etch adhesive. These liquids were mixed, applied on the test surface, and light-cured for 10 seconds. As a control, an S-PRG filler-free varnish was applied in the same manner. Each specimen was immersed in 8% methylcellulose gel demineralization system (1.5 mM Ca, 0.9 mM PO₄, 0.1 M acetic acid, pH 5.0) for 7 days at 37°C. The mineral profiles and integrated mineral loss (IML) of the lesions were obtained by transversal microradiography and analytical software. Results: The S-PRG group exhibited significantly thicker surface layer than the control group. Furthermore, the S-PRG group showed significantly lower IML (3,459 vol% × µm) than the control group (4,687 vol% × µm) (P< 0.05, Welch’s two-sample t-test). The novel fluoride-releasing varnish increased acid resistance of root dentin in the vicinity of the coated surface. (Am J Dent 2012;25:347-350).

Mail: Dr. Yoshiharu Mukai, Division of Restorative Dentistry, Department of Oral Medicine, Kanagawa Dental College, 82 Inaoka-cho, Yokosuka, Kanagawa 238-8580, Japan. E-mail: mukaiyos@kdcnet.ac.jp

Dental erosion as oral disease. Insights in etiological factors and pathomechanisms, and current strategies for prevention and therapy

Carolina Ganss, dds, phd,  Adrian Lussi, dds, phd  &  Nadine Schlueter, dds

Abstract: Dental erosion is induced by the exposure to acids, and together with physical impacts, contributes to the wear and tear of the dentition throughout a lifetime. It is a multifactorial condition, and so far several etiological and protecting factors have been identified. Based on a thorough diagnosis and identification of the acid sources, current preventive and therapeutic strategies focus on causal strategies bringing the acid exposure to a safe level, and/or strengthening the tooth surface against demineralization. There is increasing knowledge about the erosion inhibiting potential of fluorides particularly of compounds with polyvalent metal cations. The paper critically reviews the current literature providing a brief overview on what is known about diagnosis, prevalence, etiology and risk factors with the main focus on preventive and therapeutic strategies. (Am J Dent 2012;25:351-364).

Mail: Dr. Carolina Ganss, Dental Clinic, Department of Conservative and Preventive Dentistry, Schlangenzahl 14, D-35392 Giessen, Germany. E-mail: carolina.ganss@dentist.med.uni-giessen.de