Research Article

I

Bond strength of ceramic or resin CAD-CAM laminate veneers

 

Metin Bakir, dds, phd,  Şehmus Bakir, dds, phd  &  Emrullah Bahsi, dds, phd

 

Abstract: Purpose: To compare the bond strength of ceramic or resin laminate veneers produced using computer assisted design/computer assisted machining (CAD-CAM). Methods: 80 teeth were prepared for laminate veneer, and divided into eight groups of different CAD-CAM blocks in each group. Each group was restored with the manufacturers’ recommended procedures. After cementation of the veneers, all samples were thermocycled (1,000 cycles); the crowns of the teeth were embedded vertically into acrylic blocks and subjected to shear bond strength in a universal tester. Shear bond strength was determined in Newtons (N). Results: The tests showed 52.5% cohesive failure, 30% adhesive failure, and 17.5% adhesive-cohesive failure (mixed). Lava Ultimate had the highest bond strength average and the Cerec blocks had the lowest with 82.2N. Lava Ultimate, Cerasmart, and E-Max’s shear bond strength values were statistically different compared to Vitablocs Mark II, Cerec Blocs, GC Initial LRF Blocks (P< 0.05). The difference between the Vitablocs Mark II and Cerec Blocs and the Vita Enamic block was statistically significant. There was no statistically significant difference among the other groups. The selected CAD-CAM material affected the shear bond strength of the laminate veneers. (Am J Dent 2020;33:287-290).

 

 

 

 

 

 

Mail: Dr. Metin Bakir, Department of Restorative Dentistry, Faculty of Dentistry, Bingol University, Postal Code: 12100, Campus, Bingol, Turkey.  E-mail:  metinbakir88@gmail.com

 

 

A randomized controlled clinical trial of two types of lithium disilicate partial crowns

 

Edoardo Ferrari Cagidiaco, dds, msc,  Roberto Sorrentino, dds, msc, phd,  Denise I.K. Pontoriero, dds &  Marco Ferrari, md, dmd, phd

 

Abstract: Purpose: This randomized controlled clinical trial evaluated the behavior of lithium disilicate partial crowns by means of a novel Functional Index for Teeth (FIT). Methods: 105 subjects in need of at least a single prosthetic restoration in posterior areas were treated with adhesive partial crowns (for a total of 170 restorations) onto natural vital abutment teeth and followed-up annually for 4 years. Subjects were randomly divided into two experimental groups: Group 1, e.max Press and Group 2, Initial LiSi Press. FIT was used for the objective assessment of outcomes including clinical and radiographic examinations. A dropout rate of 4.25% in Group 1 and 3.4% in Group 2 was recorded. FIT is made up of seven variables (interproximal, occlusion, design, mucosa, bone, biology and margins); each of them to be evaluated using a 0-1-2 score. The Mann-Whitney U test was applied for statistical analysis and the level of significance was set at P< 0.05. Results: In Group 1, five complications were recorded, and four in Group 2, with a failure rate of 6.25% and 6.17%, respectively. No statistically significant difference was found between the experimental groups in any of the assessed variables. The tested lithium disilicate material brands showed comparable clinical performances after 4 years of clinical service. (Am J Dent 2020;33:291-295).

 

 

Mail: Prof. Marco Ferrari, Odontostomatologia, Policlinico Le Scotte, Viale Bracci 1, Siena 53100, Italy. E-mail: ferrarm@gmail.com

 

 

The clinical accuracy of the implant digital surgical guide: A meta-analysis

 

Fang Zhang, ms,  Xue Gao, ms,  Zhang-Yan Ye, ms,  Dong-qian Xu, ms  &  Xi Ding, phd

 

Abstract: Purpose: To systematically evaluate the accuracy of clinical applications of digital guides. Method: First, PubMed and Embase databases were searched using the PICO standard. Eligible articles were included. Second, the eligible articles were classified according to the different types. Next, the NOS and ROB2 as evaluation indicators were used to evaluate the bias of those included articles. Finally, sensitive factors were excluded through the outcomes and data analyses were retrieved. Results: More than 1,562 articles were retrieved, and 38 in vivo research documents were systematically analyzed after screening according to the inclusion criteria, which mainly listed three aspects of the coronal, apical, and angular implant data, and integrated the same type of articles in the study. To test its heterogeneity, the P-values of those articles included in the analysis were all less than 0.05. Finally, in the comparison between the guide group and the free-hand group after excluding sensitive factors, the standardized mean difference (Std.MD) of the angle was 1.26 (95% CI 1.06, 1.47), the Std.MD of the apical point was 1.38 (95% CI 1.12, 1.63), and the Std.MD of the coronal point was 0.98 (95% CI 0.66, 1.29). Comparing the maxillary and mandibular groups after excluding sensitive factors, the Std.MD of the coronal point was -0.31 (95% CI -0.52, -0.09), the Std.MD of the apical point was -0.15 [95% CI -0.34, 0.03], and the Std.MD of the angle is -0.23 (95% CI -0.46, 0.01). Comparison between the smoking group and the nonsmoking group, and between the flap group and the flapless group showed that there was not enough evidence to make a reliable assessment. (Am J Dent 2020;33:296-304).

 

 

Mail: Dr. Xi Ding, The First Affiliated Hospital of Wenzhou Medical University, Ouhai District, Wenzhou City, P.R.China. E-mail: dingxi@wzhospital.cn

 

 

Antimicrobial effect and physical properties of an injectable “active oxygen” gel for the treatment of periodontitis

 

Kadiatou Sy, dds, msc, Joséphine Flamme, dds, Héloïse Macquet, dds, Feng Chai, dds, phd, Christel Neut, phd, Florence Siepmann, pharm d, phd  &  Kevimy Agossa, dds, phd

 

Abstract: Purpose: To evaluate an injectable gel, recently proposed for the controlled release of “active oxygen” in periodontal pockets, compared to an antibiotic or an antiseptic gel, respectively. Methods: The antimicrobial activity, injectability, texture properties, swelling and water uptake of the gels were studied. Results: The “active oxygen” gel showed a bactericidal effect comparable to the two commercially available drug products (containing minocycline or chlorhexidine) on anaerobic periodontal pathogens and did not seem to affect aerobic strains. The gel was easy to inject and stable in an aqueous medium for several days. Texture analysis revealed potential gel fragility. (Am J Dent 2020;33:305-309).

 

 

Mail: Dr. Kevimy Agossa, Faculty of Dental Surgery, University of Lille, Place de Verdun, 59000 Lille, France. E-mail: kevimy.agossa@univ-lille.fr

 

 

 

Mechanical behavior and adhesive potential of glass fiber-reinforced resin-based composites for use as dentin analogues

 

Erlon Grando Merlo, dds, msc, Alvaro Della Bona, dds, msc, phd, Jason A. Griggs, msc, phd, Kartikeya Singh Jodha, dds, msc  &   Pedro Henrique Corazza, dds, msc, phd

 

Abstract: Purpose: To characterize experimental glass fiber-reinforced resin-based composites (GFIR-isophthalic; and GFOR-orthophthalic), evaluating their mechanical behavior and adhesive potential to ceramic in comparison to human dentin and a traditional glass fiber-reinforced epoxy resin (G10). Methods: Density (ƿ), elastic modulus (E), and Poisson's ratio (v) were evaluated using 2 mm thick specimens from GFIR, GFOR, human dentin and G10. Biaxial flexural strength (σ_f), Knoop hardness and surface topography under scanning electron microscopy (SEM) were assessed for GFIR and GFOR specimens. G10 was also tested for σ_f. For the adhesive potential, ceramic specimens (n=10) bonded to GFIR, GFOR or human dentin were tested for microtensile bond strength (MTBS). Disc-shaped ceramics were cemented onto dentin, GFIR, GFOR and G10 (n=15) and loaded to failure. Data were statistically evaluated using Weibull, ANOVA, and Tukey's test (α=0.05). Results: The experimental resins (GFIR and GFOR) showed similar values of HK (53.1 and 52.7 GPa), v (0.44 and 0.43) and σf (41.2 MPa and 40.7 MPa). Considering the human dentin values for ƿ and E, the corresponding values obtained from GFIR, GFOR and G10 were different, with GFOR values being closer to dentin than GFIR and G10. G10 had statistically greater σf than GFIR and GFOR. Mean bond strength of ceramic to GFIR, GFOR and dentin were statistically similar. The fracture load of resin-cemented ceramic was influenced by substrate. (Am J Dent 2020;33:310-314).

 

 

 

Mail: Dr. Pedro Henrique Corazza, Post-graduation Program in Dentistry, Dental School, University of Passo Fundo, Campus I, BR 285, Km 171, Passo Fundo, Rio Grande do Sul, Brazil. E-mail: pedrocorazza@upf.br

 

 

Silver diamine fluoride and cleaning methods effects on dentin bond strength

 

Paulo Vitor Fernandes Braz, dds, ms, Andressa Fabro Luciano dos Santos, dds, ms, phd, Patrícia Nóbrega Rodrigues Pereira, dds, phd, Ana Paula Dias Ribeiro, dds, ms, phd

 

Abstract: Purpose: To assess the effect of silver diamine fluoride (SDF) application on bond strength of current adhesive systems to caries-affected dentin and cleaning procedures to overcome SDF’s influence on adhesion to dentin. Methods: 64 human third molars were randomly divided in eight groups for microshear bond strength testing (MBS). Samples of sound and artificial caries-affected human dentin were treated or not with 38% SDF and restored with an etch-and-rinse or a self-etch bonding system. For the cleaning part, water, aluminum oxide, and pumice paste were used after SDF application to determine whether SDF affected the bond strength to dentin. Fracture mode was evaluated under scanning electron microscope. Data were statistically analyzed by ANOVA. Results: SDF application resulted in the lowest MBS for the self-etching adhesive system on caries-affected dentin (P< 0.05). Cleaning with pumice slurry maintained the MBS in SDF groups when compared to the control groups (not treated with SDF). Fracture evaluation showed more adhesive failures on adhesive systems groups. EDX analysis showed no silver particles when pumice paste was used for cleaning. (Am J Dent 2020;33:315-319).

 

 

Mail: Dr. Ana Paula Ribeiro Dias, Department of Restorative Dental Sciences, College of Dentistry, 1395 Center Drive, Room D1-11, University of Florida, Gainesville, FL 32610, USA.  E-mail:  aribeiro@dental.ufl.edu

 

 

Ultrasonic measurement of remaining dentin thickness using a pencil-type transducer

 

Ryosuke Murayama, me, dds, phd, Hiroyasu Kurokawa, dds, phd, Nicholas G. Fischer, bs, Carlos A. Jurado, dds, ms, Akimasa Tsujimoto, dds, phd, Toshiki Takamizawa, dds, phd, Masashi Miyazaki, dds, phd  &  Franklin García-Godoy, dds, ms, phd, phd

 

Abstract: Purpose: To evaluate the ability of a pencil-type transducer connected to a pulser-receiver to measure remaining dentin thickness (RDT). Methods: A total of 24 freshly extracted bovine incisors were used to prepare dentin disks with certain thicknesses (0.5, 1.0, 1.5 and 2.0 mm). The thicknesses of the specimens were measured with an ultrasonic technique using a pencil-type transducer, and the data obtained were compared with the direct measurement obtained using a micrometer. The Bland-Altman comparison method and paired t-test were performed at a 0.05 significance level. Results: The agreement between different measurement methods was analyzed to evaluate the inter-methodology variation. The Bland-Altman comparison method revealed a mean difference of 0.0098 ± 0.724 mm between the ultrasonic technique and the direct measurement, with the 95% Bland-Altman limits of agreement ranging from 0.1322 to 0.1517 mm. (Am J Dent 2020;33:320-324).

 

 

 

Mail: Dr. Hiroyasu Kurokawa, Department of Operative Dentistry, Nihon University School of Dentistry, 1-8-13, Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan.  E-mail:  kurokawa.hiroyasu@nihon-u.ac.jp

 

 

 

Effectiveness of two desensitizing products:  A 6-month randomized clinical, split-mouth study

 

Leyla Kerimova, dds  &  Arlin Kiremitci, dds, phd

 

Abstract: Purpose: This randomized controlled clinical trial compared the efficacy of a desensitizer containing calcium phosphate with a two-step self-etch adhesive and placebo over a 6-month period. Methods: 50 subjects aged between 21-64 years with a sensitivity score of 6 or higher according to the Visual Analog Scale (VAS) in at least three teeth participated in this study. Teethmate Desensitizer, Clearfil SE Bond 2, and placebo (distilled water) were applied randomly to three teeth of each patient. Recall reviews were performed at baseline, 1 week, 1 month, 3 months, and 6 months after treatment, and the sensitivity scores were assessed by air-blast application. The normality of data was analyzed with Shapiro-Wilk. Since the placebo treatment was successful only in a small number of teeth, the three materials could only be compared 10 minutes after the treatment. Data were analyzed with Wilcoxon Test, Friedman and Dunn post-hoc tests (P= 0.05). Results: Sensitivity decreased significantly after application for each of the three test groups when compared to the pretreatment condition (P< 0.05). There were no significant differences between the Teethmate Desensitizer and Clearfil SE Bond 2, and both materials were more effective than the placebo (P< 0.05). (Am J Dent 2020;33:325-329).

 

 

Mail: Dr. Leyla Kerimova, Department of Restorative Dentistry, School of Dentistry, Baskent University, Yukarı Bahcelievler Mahallesi, 82. Sk. No: 26, 06490 Cankaya/Ankara, Turkey. E-mail: leylakerim38@gmail.com, lkerimova@baskent.edu.tr

 

 

Effect of light-curing time on microhardness of a restorative bulk-fill resin composite to lute CAD-CAM resin composite endocrowns

 

René Daher, dr med dent, phd, Stefano Ardu, dr med dent, phd, Cornelis J. Kleverlaan, phd, Enrico Di Bella, phd, Albert J. Feilzer, dds, phd  &  Ivo Krejci, Prof. dr med dent

 

Abstract: Purpose: To evaluate the minimal irradiation time to reach a sufficient polymerization of a photopoly-merizable restorative bulk-fill resin composite to lute endocrowns. Methods: A photopolymerizable restorative bulk-fill resin composite (Filtek One Bulk Fill) was submitted to direct light-curing by a high power LED light-curing unit for 20 seconds as the positive control group (n = 10). Five more test groups (n= 10) were light-cured in a natural tooth mold from three sites (buccal, palatal and occlusal) under a 9.5 mm thick nanohybrid resin composite CAD-CAM endocrown (Lava Ultimate A2 LT), for different irradiation times: 90 seconds per site, 40 seconds per site, 30 seconds per site, 20 seconds per site and 10 seconds per site. Vickers microhardness measurements were made at two different depths and test/control ratios were calculated. Ratios of 0.8 were considered as an adequate level of curing. Results: Analysis shows that 30 seconds × 3 was the minimal irradiation time that presented a test/control ratio above 0.8. Quantile regressions showed that the required irradiation time to reach a test/control ratio of 0.8 at a confidence level of 95% was 38 seconds and 37 seconds for 200 μm and 500 μm, respectively. There was no statistically significant difference between microhardness of the two depths except for the irradiation time of 10 seconds. A 120-second (40 seconds per buccal, palatal and occlusal site) light-curing of photopolymerizable bulk-fill resin composite to lute a resin composite CAD-CAM endocrown restoration can be considered sufficient to reach adequate polymerization. (Am J Dent 2020;33:331-336).

 

 

 

 

 

 

Mail: Dr. René Daher, Department of Cariology and Endodontology, University of Geneva, 1 rue Michel-Servet, 1211 Geneva, Switzerland. E-mail: rene.daher@unige.ch