^{August 2017Abstracts}

 

 

 

 

Effects of riboflavin, calcium-phosphate layer and adhesive system on stress-strain behavior of demineralized dentin

 

Tissiana Bortolotto, dr med dent, msc, phd, pd,  Anastasia Ryabova, med dent,  Izabella Nerushay, med dent, Sabine Kling, msc, phd, Farhad Hafezi, md, phd, Franklin Garcia-Godoy, dds, ms, phd, phd  &  Ivo Krejci, dr med dent, pd

 

Abstract: Purpose: To evaluate if three dentin treatments improved mechanical properties of demineralized dentin. Methods: Dentin slices were demineralized and treated with a universal adhesive, Scotchbond Universal (SBU), a cross-linker, Riboflavin (RF), and a calcium phosphate-based product, Teethmate (TM). The groups (n= 8 per group) were: Group 1: SBU, Group 2: RF + SBU, Group 3: RF + TM + SBU. Tensile tests were performed; stress/strain curves and E modulus were calculated. Differences between groups were assessed by one-way ANOVA and Duncan post hoc test. Results: At high strains, no significant differences in E moduli were observed between dentin specimens treated only with SBU and those treated with RF + SBU. A significantly higher E modulus was observed in dentin specimens treated with RF + TM + SBU. In the presence of an adhesive system, crosslinking collagen with RF and TM addition significantly improved mechanical properties of dentin. (Am J Dent 2017;30:179-184).

 

 

 

 

 

Mail: Dr. Tissiana Bortolotto, Division of Cariology and Endodontology, University Clinic of Dental Medicine, Faculty of Medicine, University of Geneva, Rue Barthelemy-Menn, 19, 1205 Geneva, Switzerland. E-mail: Tissiana.Bortolotto@unige.ch

 

 

Differences in physical characteristics and sealing ability of three tricalcium silicate-based cements used as root-end-filling materials

 

Maximilian Kollmuss, dr med dent, dds, Carolina Elisabeth Preis, dr med dent, dds, Stefan Kist, dr med dent, dds, Reinhard Hickel, dr med dent, dds   &  Karin Christine Huth, dr med dent, mme, dds

 

Abstract: Purpose: To evaluate differences in physical characteristics and sealing ability of root-end-fillings made with these materials compared to the gold standard (ProRoot MTA). Methods: The physical characteristics of ProRoot MTA, Medcem MTA and Biodentine were evaluated regarding setting time, flow, film thickness, solubility and radiopacity according to the German Institute for Standardization (EN-ISO 6878). To investigate their sealing ability as root-end-fillings, a glucose penetration model was used. 60 human extracted single-rooted teeth were endodontically treated, root-end resections performed and divided in three groups of 20 teeth, using either ProRoot MTA, Medcem MTA or Biodentine as root-end-filling material. After 30 days, glucose concentrations were determined photometrically, followed by statistical analysis (Kruskal-Wallis test, Mann-Whitney U-test). Results: Biodentine showed the fastest setting time (< 12 minutes) and lowest film thickness (0.11± 0.01 mm), whereas Medcem MTA showed the best values regarding solubility (< 0.1%) and flow (9.5± 0.02 mm). ProRoot MTA revealed the highest radiopacity (7.58±0.1 mm aluminum equivalent). The glucose leakage in the Medcem MTA group was significantly lower than in the ProRoot MTA group (P= 0.011). Biodentine showed lower leakage than ProRoot MTA (P= 0.031). (Am J Dent 2017:30:185-189).

 

 

 

 

Mail: Dr. Maximilian Kollmuss, Department of Conservative Dentistry and Periodontology, University Hospital, LMU Munich, Goethestraße 70, D-80336 Munich, Germany. E-mail: kollmuss@dent.med.uni-muenchen.de

 

 

 

 

 

 

 

 

 

Comparison of different maintenance strategies within supportive implant

therapy for prevention of peri-implant inflammation during the first year

after implant restoration. A randomized, dental hygiene practice-based

multicenter study

 

Dirk Ziebolz, drmeddent, msc, Sandra Klipp, Gerhard Schmalz, drmeddent, Jan Schmickler, drmeddent, Sven Rinke, drmeddent, msc, msc, Tanja Kottmann, drmed, Sylvia Fresmann  &  Johannes Einwag, prof drmeddent

 

Abstract: Purpose: This randomized clinical multicenter study compared different professional preventive approaches on peri-implant inflammation under supportive implant therapy (SIT). Methods: 105 participants (167 implants) were randomly allocated to four groups. All participants were under SIT with a 3-month recall interval. Plaque removal was performed by using manual curettes, a sonic-driven scaler, and a prophylaxis brush (Group A), supplemented by chlorhexidine (CHX) varnish on the implant surfaces (Group C) or by using manual curettes, air polishing with glycine powder, and a prophylaxis brush (Group B), supplemented by treatment with CHX varnish on the implant surfaces (Group D). The peri-implant probing depths (PPD), mucosal recession (MR), and bleeding on probing (BOP) on implants were determined at baseline. After 12 months, the final PPD, MR, and BOP on implants were assessed. The statistical evaluation consisted of Kruskal-Wallis-test, Wilcoxon-test and Chi-squared test modified according to McNemar (P< 0.05). Results: 62 subjects (n= 101 implants) were available for assessment. In Groups A, C, and D, no significant implant-related differences between baseline and follow-up were found in PPD, MR, and BOP. Group B showed a significant difference (P= 0.022) between baseline (1.77 ± 1.58 mm) and follow-up (2.31 ± 1.54 mm) in PPD. The location of implant (P= 0.02), the type of implant (P= 0.01), and the age of subject (P= 0.04) had significant influences on BOP. (Am J Dent 2017;30:190-196).

 

 

 

 

 

 

Mail: PD Dr. Dirk Ziebolz, University Medical Center Leipzig, Dept. of Cariology, Endodontology and Periodontology, Liebigstr. 10-14, D 04103 Leipzig, Germany. E-mail: dirk.ziebolz@medizin.uni-leipzig.de

 

 

 

 

Fracture resistance of endodontically-treated mandibular molars restored

with different intra-radicular techniques

 

Nada Alarami, bds, mdsc, Eshamsul Sulaiman, bds, mfdrcs, mclindent &  Afaf Al-Haddad, bds, mdsc, phd

 

Abstract: Purpose: To evaluate fracture resistance and failure mode of endodontically-treated mandibular molars restored with different intra-radicular techniques. Methods: 75 human mandibular molars were randomly divided into five equal groups. Teeth were standardized, endodontically-treated and restored according the assigned group as follows: amalgam core only, prefabricated titanium post in the distal canal and amalgam core, composite core only; fiber post in the distal canal and composite core. One group of untreated sound teeth was used as a control. Non-precious metal crowns were fabricated and cemented on the prepared specimens with Rely X U200 resin cement. All specimens were subjected to a compressive load at crosshead speed 0.5 mm/minute, 25° to the long axis of the tooth. Failure loads and modes were recorded. Results: Mean failure loads among the groups were significantly different (P= 0.035). Post-hoc multiple pair-wise comparisons revealed the amalgam core and composite core groups produced significantly lower fracture resistance than the control group (P= 0.041 and P= 0.025, respectively) and no significant differences among the different intra-radicular techniques (P> 0.05). The composite core with fiber post and amalgam core with titanium posts showed the highest percentage of favorable failures (67%) and non-favorable failures (87%) respectively. (Am J Dent 2017:30:197-200).

 

 

 

 

 

 

 

 

 

 

 

 

Mail: Nada Alarami, Department of Restorative Dentistry, Faculty of Dentistry, University of Malaya, 50603 Kuala Lumpur, Malaysia. E-mail: nada_alarmi@yahoo.com

 

 

Clinical efficacy of resin-based materials for dentin hypersensitivity treatment

 

Gabriela D. Canali, dds, msd,  Sergio A. Ignácio, phd,  Rodrigo N. Rached, dds, msd, phd

&  Evelise M. Souza, dds, msd, phd

 

Abstract: Purpose: To evaluate the effect of three resin-based materials in the treatment of dentin hypersensitivity (DH) up to a 6-month follow-up. Methods: 30 participants (179 teeth) with DH were enrolled in this randomized, double-blind, controlled clinical study. The teeth were randomly allocated into one of three groups: CV (resin-modified glass ionomer varnish - Clinpro XT Varnish), CP (fluoride-containing self-etch adhesive - Clearfil SE Protect) and GB (glutaraldehyde-containing etch-and-rinse adhesive - Gluma 2 Bond). The materials were applied according to the manufacturer's instructions. DH was evaluated by subjects’ perception measured on a 0-10 visual analog scale (VAS) after evaporative (air blast) stimuli. The scores were recorded at baseline, immediately and at 1, 3 and 6 months after treatment. The data were analyzed by a two-way ANOVA with repeated measures for “time” and Games-Howell test (α= 0.05). Results: ANOVA detected statistically significant differences among the time intervals, but not among the materials or interactions. There was a significant decrease in sensitivity scores from baseline to all the time points (P< 0.05). However, the differences were not statistically significant among the follow-ups, from immediately until 6 months after treatment (P> 0.05). All the resin-based materials were able to reduce DH up to 6 months after treatment. (Am J Dent 2017;30:201-204).

 

 

Mail: Dr. Evelise M. Souza, R. Imaculada Conceição, 1155, 80215-901 Curitiba, PR – Brazil. E-mail: evesouza@ yahoo.com, evelise.souza@pucpr.br

 

 

 

Bond strength and cement-tooth interfacial characterization of self-adhesive composite cements

 

U. Burak Temel, dds, phd, Annelies Van Ende, dds, phd, Bart Van Meerbeek, dds, msc, phd  &  R. Banu Ermis, dds, phd

 

Abstract: Purposes: (1) To determine the microtensile bond strength (µTBS) of self-adhesive (SA) composite cements to unetched/etched enamel and dentin, and (2) to characterize the cements' interaction with tooth tissue. Methods: 51 composite blocks were bonded to smear layer-covered enamel and dentin (three teeth per group). Four SA composite cements (Clearfil SA, G-CEM, RelyX Unicem, SmartCem2), and three multi-step composite cements, two used following an etch-and-rinse (E&R) approach (RelyX ARC, Variolink II ‘E&R’) and one used following a self-etch (SE) approach (Variolink II ‘SE’) were investigated. The cement-tooth specimens were perpendicularly sectioned into micro-specimens (1.0 × 1.0 mm) in order to measure the µTBS. The data were statistically analyzed by ANOVA followed by Tukey HSD (P< 0.05). 24 additional specimens (four teeth per group) were prepared for interfacial characterization using SEM. Results: The tested SA cements bonded equally well to enamel and dentin. Etching of enamel improved their bonding effectiveness, which however remained inferior to that of both E&R cements. SEM revealed a very similar interfacial ultrastructure at smear layer-covered enamel and dentin for the SA cements, exhibiting very superficial interaction at enamel and absence of a clearly detectable hybrid layer and resin tags in the dentin tubules. When the SA composite cements were applied to dentin free of a smear layer, regular and long resin tags were formed. (Am J Dent 2017;30:205-211).

 

 

 

 

 

Mail: Prof. Bart Van Meerbeek, Department of Oral Health Sciences, BIOMAT, KU Leuven (University of Leuven), Kapucijnenvoer 7, block A - Box 7001, 3000 Leuven, Belgium. E-mail: bart.vanmeerbeek@kuleuven.be

 

 

 

Occlusal stress is involved in the formation of non-carious cervical lesions.

A systematic review of abfraction

 

Duangporn Duangthip, dds, dr med dent, phd,  Arthur Man, Pak Hong Poon,  Edward Chin Man Lo, bds, mds, phd &  Chun-Hung Chu, bds, mds, phd

 

Abstract: Purpose: This systematic review on abfraction studied whether stress is a mechanism in the formation of non-carious cervical lesions (NCCLs). Methods: A literature search was performed on three electronic databases (PubMed, ISI Web of Science, and EMBASE) using the keyword “abfraction” in publications published in English. The inclusion critera were clinical and laboratory studies that investigated the role of abfraction in NCCLs. The title and abstract of the identified publications were screened by two investigators independently. Reviews, case reports, and irrelevant papers were excluded. Full text of the remaining publications were retrieved. A manual search was performed on the bibliographies of the selected publications to identify additional relevant publications for review. Results: A total of 372 publications were identified, and 165 duplicated publications and 166 irrelevant publications were excluded. From the bibliographies of the remaining 41 publications, 28 relevant publications were found. Therefore, 69 publications (31 clinical studies and 38 laboratory studies) were included in this review and the majority (56/69, 81%) found an association between occlusal stress and NCCLs. Although no clinical study demonstrated that NCCL was caused by stress alone, 23 studies reported that stress or occlusal factors were associated with NCCLs. Of the 38 laboratory studies, 24 that used finite element analysis found that stress was concentrated at the cervical region of the tooth. Nine laboratory studies suggested that stress was a mechanism for NCCLs, whereas five studies reported the opposite. In conclusion, current literature supported an association between occlusal stress and NCCLs. (Am J Dent 2017;30:212-220).

 

 

 

Mail: Dr. Chun Hung Chu, 3/F, Prince Philip Dental Hospital, Operative Dentistry, Faculty of Dentistry, The University of Hong Kong, 34 Hospital Road, Hong Kong. E-mail: chchu@hku.hk

 

 

 

Effectiveness of dentifrices with new formulations for the treatment of dentin hypersensitivity - A meta-analysis

 

Christina Grünberg, dmd, Florian Bauer, md, dds, phd, Alexander Crispin, md, Michael Jakob, dmd, Reinhard Hickel, dmd, phd  &  Miriam E. Draenert, dmd, phd

 

Abstract: Purpose: This meta-analysis was conducted to evaluate if strontium-acetate- and arginine-containing dentifrices can significantly reduce dentin hypersensitivity (DH). Methods: A systematic literature search was performed. The investigation period was from 2006 to 2015 with the search term "dentin hypersensitivity". Nine original articles were relevant. A network meta-analysis of combined z scores was performed. Pooled results from random effects models with their 95% confidence intervals are reported. Results: The results from the random effects network meta-analysis show a significant improvement for the agents strontium acetate, arginine, and arginine with whitener, at all times for all stimuli, in comparison with the placebo. Strontium chloride is equivalent to the placebo. None of the dentifrices had a negative effect on DH. This meta-analysis showed that strontium-acetate- and arginine-containing dentifrices can significantly reduce DH. Calcium sodium silicate and potassium nitrate formulas show a tendency for pain relief. Because of the limited power of the available studies, a randomized study with several agents is recommended. (Am J Dent 2017;30:221-226).

 

 

 

 

 

Mail: Dr. Christina Grünberg, Department of Operative Dentistry and Periodontology, Ludwig-Maximilians University, Munich, Goethestrasse 70, D-80336 Munich, Germany. E-mail: gruenberg@dent.med.uni-muenchen.de

 

 

 

Stress distribution of bulk-fill resin composite in class II restorations

 

Pietro Ausiello, dds, phd, Stefano Ciaramella, eng, phd, Franklin Garcia-Godoy, dds, ms, phd, phd

Massimo Martorelli, eng, phd, Roberto Sorrentino, dds, phd  &  Antonio Gloria, eng, phd

 

Abstract: Purpose: To study the influence of the resin bonding layer thickness and the bulk filling material stiffness in adhesive class II mesio-occlusal-distal (MOD) restorations using numerical finite element analysis (FEA). Methods: Four 3D-FE models of teeth restored with different filling material stiffness and resin bonding layer thickness were built-up and analyzed. The 3D model of a sound lower molar was also analyzed and compared with restored ones. The tooth tissues (enamel, dentin), dental restoration and bolus on the occlusal surface, was divided into 3D solid CTETRA elements with four grid points. The adhesive bonding around the dental restoration was modeled with shell elements. Polymerization shrinkage was simulated with a thermal expansion approach. Mechanical behavior of restored models in terms of stress and displacement distributions, under the combination effects of polymerization shrinkage and occlusal load (600 N), was analyzed. All the materials were assumed to behave as elastic materials throughout the entire deformation. Results: Numerical results show that the mechanical response of the restored models was very different compared to the sound tooth ones, where the stress was uniformly distributed from enamel to dentin with no critical stress concentration. In the restored models, the highest stress values were detected in the enamel, near the enamel-dentin interface and in the bulk restorative material. Tooth preparations A and B showed lower gradient stresses than corresponding C and D. The value of the vertical displacement components in models A and B were higher than corresponding C and D. The maximum displacement values were mainly located around the groove and were higher by an order of magnitude than the sound models. The results showed better mechanical response with models A and B compared to C and D. It is also evident that resin bonding thickness slightly affected the stress level of the restored teeth. (Am J Dent 2017;30:227-232).

 

 

Mail: Dr. Pietro Ausiello, Department of Dental Materials and Restorative Dentistry, School of Dentistry, University of Naples Federico II, Via S. Pansini 5, 80131 Naples, Italy.  E-mail:  pietro.ausiello@unina.it