Operative Dentistry (OPER DENT)

Publications in this journal

• Article: Influence of the Examiners' Experience on Clinical Performance of Visual Inspection in Detecting and Assessing the Activity Status of Caries Lesions.

  T Gimenez, Dg Bittar, C Piovesan, Cab Guglielmi, Ky Fujimoto, R Matos, Tf Novaes, Mm Braga, Fm Mendes
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  ABSTRACT: SUMMARY Our hypothesis was that a method of caries activity evaluation based on the clinical features of the lesions would be less time consuming but more influenced by the examiner's experience than the scoring system used in association with the International Caries Detection and Assessment System (ICDAS). Thus, the aim of this study was to evaluate the performance of three groups of examiners with different levels of experience using two different methods to assess the activity status of caries lesions by visual inspection. A cross-sectional study in a dental office setting was performed selecting 18 children, aged three to eight years, who had sought dental treatment at a dental school. Examinations to detect caries lesions were performed using visual inspection by six examiners with different levels of experience: two undergraduate dental students, two specialists in pediatric dentistry, and two graduate students. The examiners used ICDAS and two different methods to assess caries activity: using an additional score system or considering the examination of clinical features. Two benchmark examiners examined the children in a joint session, and their consensus was considered to be the reference standard. The sensitivity, specificity, and reproducibility were calculated for different thresholds: all, cavitated, and active caries lesions. Multilevel analyses were performed to compare the different methods and examiners. No differences were observed among the examiners, either in detecting all lesions and cavitated lesions or regarding the activity assessment. The methods of assessing activity status performed similarly, but the time spent on examinations was shorter for the method evaluating clinical features. In conclusion, the experience of examiners does not significantly influence the performance of visual inspection, and both methods of assessing activity status result in similar diagnostic accuracy.
  Operative Dentistry 04/2013;
• Article: Clinical Performance of Ormocer, Nanofilled, and Nanoceramic Resin Composites in Class I and Class II Restorations: A Three-year Evaluation.

  Sh Mahmoud, Ae El-Embaby, Am Abdallah
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  ABSTRACT: SUMMARY Purpose : This prospective long-term clinical trial evaluated and compared the three-year clinical performance of an ormocer, a nanofilled, and a nanoceramic resin composite with that of a microhybrid composite placed in Class I and Class II cavities. Methods : Forty patients, each with four Class I and II restorations under occlusion, were enrolled in this study. A total of 160 restorations were placed, 25% for each material, as follows: an ormocer-based composite, Admira; a nanofilled resin composite, Filtek Supreme XT; a nanoceramic resin composite, Ceram X; and a microhybrid resin composite, Tetric Ceram. A single operator placed all restorations according to the manufacturers' instructions. Immediately after placement the restorations were finished/polished. Clinical evaluation was performed at baseline and at yearly intervals after placement by two other independent examiners using modified US Public Health Service (USPHS) criteria. The changes in the USPHS parameters during the three-year period were analyzed with the Friedman test. Comparison of the baseline scores with those at the recall visits was made using the Wilcoxon signed rank test. The level of significance was set at p < 0.05. Results : All materials showed only minor changes, and no differences were detected between their performance at baseline and after three years. Only two ormocer, one nanofilled, and one microhybrid restorations in molars failed because of loss of retention. Regarding the clinical performance, there were no statistically significant differences among the materials used (p>0.05). Conclusions : The ormocer, nanofilled, and nanoceramic composites provided acceptable clinical performance over a three-year period.
  Operative Dentistry 04/2013;
• Article: Evaluation of Resin Bond Strength to Yttria-stabilized Tetragonal Zirconia and Framework Marginal Fit: Comparison of Different Surface Conditionings.

  A Vanderlei, Ma Bottino, Lf Valandro
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  ABSTRACT: SUMMARY The purpose of this study was to evaluate the effect of different surface treatments of yttria-stabilized tetragonal zirconia (Y-TZP) on bond strength durability and marginal discrepancies. For adhesion testing, 144 specimens of VITA In-Ceram YZ ceramic for InLab were obtained (5.25×3.75×4.5 mm) and divided into six groups (n=24) according to the surface treatment: 1) Control (CRTL): untreated; 2) SIL: tribochemical silica coating (CoJet system, 3M/ESPE AG); 3) V1+HF: spray application of low-fusing porcelain glaze (V1, VITA Akzent Spray Glaze) followed by etching with hydrofluoric acid (HF) (one minute); 4) V1+SIL: V1 glazing (VITA Akzent Spray Glaze) followed by tribochemical silica coating; 5) V2+HF: brush application of low-fusing porcelain glaze (VITA Akzent Glaze) plus etching with HF (one minute); and 6) V2+SIL: V2 glazing (VITA Akzent Glaze) plus tribochemical silica coating. After all treatments, the surfaces were silanized for five minutes (ESPE-SIL) and cementation was performed using Panavia F (Kuraray). Half of the specimens in each treatment were tested 24 hours after cementation (dry), with the other half subjected to storage (150 days) and thermocycling (12,000×) (aging), and then a shear test was carried out (1 mm/min). The micromorphological (digital optical profilometry and scanning electron microscopy) and elemental analyses of the treated surfaces were performed. The inner surfaces of 60 Y-TZP infrastructures were conditioned and marginal fit was evaluated. The statistical analysis revealed that the groups treated via surface glaze application followed by hydrofluoric acid etching and silanization showed the highest bond strength (in dry and aging conditions), but the bond strengths were affected by aging. The highest marginal discrepancies were observed in the groups receiving glaze (117.4 ± 29.6 to 105.8 ± 12.2 μm) when compared to other groups (55.3 ± 8.7 and 55 ± 8.5 μm). Low-fusing porcelain glaze + hydrofluoric acid etching changed the morphology of the Y-TZP ceramic and improved the adhesion to the resin cement, but obtaining high and stable bond values to Y-TZP remains challenging. Marginal discrepancies increased with glazing.
  Operative Dentistry 04/2013;
• Article: The Effect of Perioperative Ibuprofen Use on Tooth Sensitivity Caused by In-Office Bleaching.

  E Paula, S Kossatz, D Fernandes, A Loguercio, A Reis
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  ABSTRACT: SUMMARY Objective : This study determined the effect of the administration of perioperative ibuprofen 400 mg on tooth sensitivity caused by in-office bleaching. Methods : A triple-blind, parallel-design, randomized clinical trial was conducted on 30 adults who received placebo or ibuprofen before and after bleaching. The drugs were administered three times per day for 48 hours; the first dose was given one hour prior to the bleaching treatment. Two bleaching sessions with 35% hydrogen peroxide gel were performed with a one-week interval. Tooth sensitivity was recorded on two scales: visual analogue and five-point verbal rating scale up to 48 hours after bleaching. The shade evaluation was performed with a visual shade guide and spectrophotometer, before and 30 days after bleaching. The absolute risk of tooth sensitivity and its intensity were evaluated by Fisher exact and Mann-Whitney tests, respectively. The shade changes were evaluated by Student's t-test. Results : Both groups showed similar absolute risk of tooth sensitivity (p>0.05). Lower tooth sensitivity was observed in the experimental group only up to one hour postbleaching (p=0.04). Similar tooth sensitivity was observed in the other periods of time. Conclusion : The perioperative use of the anti-inflammatory ibuprofen was not able to avoid tooth sensitivity but reduced its intensity up to one hour after bleaching.
  Operative Dentistry 04/2013;
• Article: Ceramic Fragments and Metal-free Full Crowns: A Conservative Esthetic Option for Closing Diastemas and Rehabilitating Smiles.

  Me Miranda, Ka Olivieri, Fj Rigolin, Rt Basting
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  ABSTRACT: SUMMARY Dental ceramics make it possible to restore anterior teeth that have been esthetically compromised, presenting a high resistance to wear, biocompatibility, color stability, and low thermal conductivity. The development of different types of ceramic and techniques for adhesive cementation have made it possible to produce more conservative restorations without involving the healthy dental structure and with minimally invasive preparation, such as the bonding of ceramic fragments. The purpose of this article is to describe a clinical case in which diastemas were closed by using nanofluorapatite ceramic (e.max Ceram, Ivoclar-Vivadent) fragments on teeth 7 and 10 with minimal tooth preparation and metal-free ceramic crowns (e-max Ceram) reinforced with zirconia copings through a computer-aided design/computer-aided manufacturing system (Lava, 3M-ESPE) on teeth 8 and 9.
  Operative Dentistry 04/2013;
• Article: The Evaluation of Working Casts Prepared from Digital Impressions.

  Yc Hwang, Ys Park, Hk Kim, Ys Hong, Js Ahn, Jj Ryu
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  ABSTRACT: SUMMARY Objective : The aim of this study is to evaluate the reproducibility of working casts of a digital impression system by comparing them with the original, virtual, and rapid prototyping casts. Materials and Methods : A total of 54 cast sets in clinically stable occlusion were used. They were scanned by an iTero intraoral scanner and converted into STL format virtual casts. Rapid prototyping casts and polyurethane casts were fabricated from the iTero milling system based on the virtual casts. Several horizontal and vertical measurements were performed from the four types of casts, that is, original stone casts, virtual casts, rapid prototyping casts, and polyurethane casts of iTero. Measurement error, intraclass correlation coefficient (ICC), and differences among the casts were calculated and compared. Results : Casts from iTero milling machines exhibited greater dimensional differences and lower ICC values than did other casts. In addition, many of the measurements of the iTero working casts showed statistically significant differences in comparison to the three other types of casts. In contrast, there were no statistically significant differences between the virtual and original casts. Conclusion : Virtual casts made by the iTero intraoral scanner exhibited excellent reproducibility. However, the casts from the iTero milling machine showed greater dimensional differences and lower reproducibility compared to other types of casts.
  Operative Dentistry 04/2013;
• Article: Composite vs Ceramic Computer-aided Design/Computer-assisted Manufacturing Crowns in Endodontically Treated Teeth: Analysis of Marginal Adaptation.

  A Ramírez-Sebastià, T Bortolotto, M Roig, I Krejci
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  ABSTRACT: SUMMARY Objectives : To compare the marginal adaptation between ceramic and composite CEREC crowns in endodontically treated teeth restored with endocrowns or with a short or a long post. Methodology : Forty-eight intact maxillary incisors were used. After endodontic treatment, the crowns were sectioned 2 mm coronally to the cemento-enamel junction, which provided a ferrule of 2 mm. The prepared teeth were divided randomly into six groups (n=8). Group 1 was restored with a large fiberglass post, composite core, and ceramic full-coverage computer-aided design/computer-assisted manufacturing (CAD-CAM) crown. Group 2 was restored with a short fiberglass post, composite core, and ceramic full-coverage CAD-CAM crown. Group 3 was restored with a large fiberglass post, composite core, and composite full-coverage CAD-CAM crown (LPCpr). Group 4 was restored with a short fiberglass post, composite core, and composite full-coverage CAD-CAM crown (SPCpr). Groups 5 and 6 were restored with ceramic and composite CEREC machined endocrowns, respectively (EndoCer and EndoCpr). The restored teeth were loaded thermomechanically in a computer-controlled chewing machine. Impressions of each restoration were made in a polyvinylsiloxane material before and after loading. Gold-coated epoxy replicas were prepared for scanning electron microscopy examination at 200× magnification. Results : Loading had a statistically significant effect (p<0.05) on the percentage of "continuous margin" in all groups. The LPCpr, SPCpr, and EndoCpr groups showed the highest percentage of continuous margin initially and after loading. The effect of the different post lengths on marginal adaptation was not significant (p>0.05). Conclusion : CAD-CAM crowns fabricated from millable composite resin blocks (Paradigm MZ100) offer a superior option to all-ceramic crowns (IPS Empress CAD).
  Operative Dentistry 04/2013;
• Article: Bulk-fill Resin-based Composites: An In Vitro Assessment of Their Mechanical Performance.

  N Ilie, S Bucuta, M Draenert
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  ABSTRACT: SUMMARY The study aimed to assess the mechanical performance of seven bulk-fill RBCs (Venus Bulk Fill, Heraeus Kulzer; SureFil SDR flow, Dentsply Caulk; x-tra base and x-tra fil, VOCO; Filtek Bulk Fill, 3M ESPE; SonicFill, Kerr; Tetric EvoCeram Bulk Fill, Ivoclar Vivadent) by determining their flexural strength (σ), reliability (Weibull parameter, m), flexural modulus (Eflexural), indentation modulus (YHU), Vickers hardness (HV), and creep (Cr). The significant highest flexural strengths were measured for SonicFill, x-tra base, and x-tra fil, while x-tra base, SureFil SDR flow, and Venus Bulk Fill showed the best reliability. The differences among the materials became more evident in terms of Eflexural and YHU, with x-tra fil achieving the highest values, while Filtek Bulk Fill and Venus Bulk Fill achieved the lowest. The enlarged depth of cure in bulk-fill RBCs seems to have been realized by enhancing the materials' translucency through decreasing the filler amount and increasing the filler size. The manufacturer's recommendation to finish a bulk-fill RBC restoration by adding a capping layer made of regular RBCs is an imperative necessity, since the modulus of elasticity and hardness of certain materials (SureFil SDR flow, Venus Bulk Fill, and Filtek Bulk Fill) were considerably below the mean values measured in regular nanohybrid and microhybrid RBCs. The class of bulk-fill RBCs revealed similar flexural strength values as the class of nanohybrid and microhybrid RBCs, and significantly higher values when compared to flowable RBCs. The modulus of elasticity (Eflexural), the indentation modulus (YHU), and the Vickers hardness (HV) classify the bulk-fill RBCs as between the hybrid RBCs and the flowable RBCs; in terms of creep, bulk-fill and the flowable RBCs perform similarly, both showing a significantly lower creep resistance when compared to the nanohybrid and microhybrid RBCs.
  Operative Dentistry 04/2013;
• Article: Effect of Postoperative Peroxide Bleaching on the Marginal Seal of Composite Restorations Bonded with Self-etch Adhesives.

  A Roubickova, M Dudek, L Comba, D Housova, P Bradna
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  ABSTRACT: SUMMARY The aim of this study was to determine the effect of peroxide bleaching on the marginal seal of composite restorations bonded with several adhesive systems. Combined cylindrical Class V cavities located half in enamel and half in dentin were prepared on the buccal and lingual surfaces of human molars. The cavities were bonded with the self-etch adhesives Clearfil SE-Bond (CLF), Adper Prompt (ADP), and iBond (IBO) and an etch-and-rinse adhesive Gluma Comfort Bond (GLU) and restored with a microhybrid composite Charisma. Experimental groups were treated 25 times for eight hours per day with a peroxide bleaching gel Opalescence PF 20, while the control groups were stored in distilled water for two months and then subjected to a microleakage test using a dye penetration method. Scanning electron microscopy was used to investigate the etching and penetration abilities of the adhesives and morphology of debonded restoration-enamel interfaces after the microleakage tests. Statistical analyses were performed using nonparametric Kruskal-Wallis, Mann-Whitney, and Wilcoxon tests at p=0.05. The microleakage of all GLU groups was low and not significantly affected by peroxide bleaching. Low microleakage was recorded for CLF control groups, but after bleaching, a small but significant increase in microleakage at the enamel margin indicated its sensitivity to peroxide bleaching. For ADP and IBO control groups, the microleakage at the enamel margins was significantly higher than for GLU and CLF and exceeded that at the dentin margins. Bleaching did not induce any significant changes in the microleakage. Electron microscopy analysis indicated that in our experimental setup, decreased adhesion and mechanical resistance of the ADP- and IBO-enamel interfaces could be more important than the chemical degradation effects induced by the peroxide bleaching gel.
  Operative Dentistry 04/2013;
• Article: Clinical Effects of Exposure to Coffee During At-home Vital Bleaching.

  M Rezende, Ad Loguercio, A Reis, S Kossatz
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  ABSTRACT: SUMMARY The purpose of the present study was to evaluate whether exposure to coffee during bleaching treatment with 16% carbamide peroxide (CP) affects the degree of whitening and tooth sensitivity. Forty patients with central incisors darker than A2 were selected. Participants who did not drink coffee were assigned to the control group (CG), while participants who drink coffee at least twice a day were assigned to the experimental group (EG). For CG, foods with dyes were restricted. For EG there was no restriction on food and patients were asked to make coffee rinses for 30 seconds, four times daily. For both groups 16% CP was used for a period of three hours daily for three weeks. Shade evaluation was assessed visually by Vita classical shade guide and by the Easyshade spectrophotometer at baseline, during bleaching (first, second, and third weeks), and postbleaching (one week and one month). Patients recorded their sensitivity perceptions by means of the numerical rating scale and 0-10 visual analog scales. Variation in shade guide units and the two colors (ΔE) were evaluated by two-way analysis of variance and Tukey tests (α=0.05). Absolute risk of tooth sensitivity and intensity of tooth sensitivity was evaluated by Fisher exact and Mann-Whitney tests (α=0.05). Effective bleaching was observed for both groups after three weeks, without statistical difference. No difference in terms of risk of tooth sensitivity and intensity of tooth sensitivity was detected between groups. Approximately 57% of the participants experienced tooth sensitivity, which was recorded mainly as "mild." Exposure to coffee during bleaching treatment does not seem to affect the degree of bleaching and tooth sensitivity.
  Operative Dentistry 04/2013;
• Article: Two-Year Clinical Performance of a Low-Shrinkage Composite in Posterior Restorations.

  B Baracco, J Perdigão, E Cabrera, L Ceballos
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  ABSTRACT: SUMMARY Objectives : The aim of this study was to compare the two-year clinical performance of three restorative systems in posterior restorations, which included a low-shrinkage composite and both etch-and-rinse and self-etch adhesive strategies. Materials and Methods : After signing an informed consent, 25 patients received three Class I (occlusal) or Class II restorations performed with one of three restorative systems: Filtek Silorane Restorative System, Adper Scotchbond 1 XT (a two-step etch-and-rinse adhesive) with Filtek Z250, and Adper Scotchbond SE (a two-step self-etch adhesive) with Filtek Z250. All materials were applied following the manufacturer's instructions. Two blind observers evaluated the restorations at three different moments (baseline; and after one and two years) according to the US Public Health Service modified criteria. Kruskal-Wallis test and Mann-Whitney U-test were used to compare the behavior of the restorative systems, while Friedman and Wilcoxon tests were applied to analyze the intra-system data (p<0.05). Results : The three restorative systems showed a statistically similar clinical performance at two years. Intra-system comparisons between baseline and two years showed declining marginal adaptation scores in the restorations placed with all systems. In addition, marginal staining and surface roughness scores were lower after two years for the restorations placed with Adper Scotchbond SE + Filtek Z250. Conclusions : Although the clinical performance of Filtek Silorane was considered acceptable after two years, no advantage of the silorane-based resin over the methacrylate-based composite was found. Teeth restored with Adper Scotchbond SE showed a tendency for marginal staining, which may compromise the final color of the restorations.
  Operative Dentistry 04/2013;
• Article: Sealing Properties of Three Luting Agents Used for Complete Cast Crowns: A Bacterial Leakage Study.

  O Zmener, Ch Pameijer, Smh Rincon, Sa Serrano, C Chaves
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  ABSTRACT: SUMMARY Objective : To assess the sealing properties of three different luting materials used for cementation of full cast crowns on extracted human premolars. Methods : Thirty noncarious human premolars were prepared in a standardized fashion for full cast crown restorations. All margins were placed in dentin. After impressions of the preparations, stone dies were fabricated on which copings were waxed, which were cast in type III alloy using standardized laboratory methods. Teeth were randomly assigned to three groups of 10 samples each (n=10), for which the following cements were used: 1) a resin-modified glass ionomer cement, Rely X Luting Plus (3M ESPE, St Paul, MN, USA); 2) a self-adhesive resin cement, Maxcem Elite (Kerr Corporation, Orange, CA, USA); and 3) a glass ionomer cement, Ketac Cem (3M ESPE), the latter used as control. After cementation the samples were allowed to bench-set for 10 minutes, stored in water at 37°C, subjected to thermal cycling (2000×, between 5°C and 55°C, dwell time 35 seconds), and then stored in sterile phosphate buffer for seven days at 37°C. Subsequently, the occlusal surface was carefully reduced until the dentin was exposed. Finishing on wet sand paper removed the gold flash caused by grinding. After sterilization, the specimens were subjected to bacterial microleakage in a dual chamber apparatus for 60 days. Bacterial leakage was checked daily. Data were analyzed using the Kaplan-Meier survival test. Significant pairwise differences were analyzed using the log-rank test followed by Fisher exact test at a p<0.05 level of significance. Results : Rely X Luting Plus showed the lowest microleakage scores, which statistically differed significantly from Maxcem Elite and Ketac Cem (p<0.05). Conclusions : Rely X Luting Plus cement displayed significantly lower microleakage scores than a self-adhesive resin-based and conventional glass ionomer cement.
  Operative Dentistry 04/2013;
• Article: In Vitro Evaluation of the Effect of Different Endodontic Sealers on Retentive Strength of Fiber Posts.

  K Aleisa, Zn Al-Dwairi, E Lynch, Cd Lynch
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  ABSTRACT: SUMMARY Purpose : There is limited information in the literature regarding the effect of different endodontic sealers on the bond strength of fiber posts luted with core buildup materials. The purpose of this study was to evaluate the effect of three different root canal sealers on the retentive strength of prefabricated fiber posts luted with a composite resin cement. Materials and Methods : Fifty-four extracted single-rooted mandibular premolar teeth were prepared and randomly divided into three groups. The first two groups were obturated with gutta-percha and one of two eugenol-based root canal sealers (Endofil, Tubli-Seal). The third group (control) was obturated with gutta-percha and a resin-based root canal sealer (AH26). Prefabricated fiber posts were luted into the prepared post spaces with a composite resin cement (Multicore Flow). The pullout forces required for dislodgment of posts from their prepared post spaces were recorded. Data were collected and statistically analyzed. Results : The AH26 group had significantly greater retentive strengths for the posts when compared with the Endofil and Tubli-Seal (eugenol-based sealers) groups (p<0.0001). There was no significant difference between the means of the retentive strengths for the Endofil and Tubli-Seal groups (p=0.745). Conclusion : The chemical formulation of root canal sealers significantly affected the retentive strength for prefabricated fiber posts luted with a resin cement. Eugenol-based sealers significantly reduced the bond strength of prefabricated fiber posts luted with resin cement.
  Operative Dentistry 04/2013;
• Article: Porcelain Veneers as an Alternative for Esthetic Treatment: Clinical Report.

  Bt Rotoli, Danl Lima, Np Pini, Fhb Aguiar, Gds Pereira, Lams Paulillo
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  ABSTRACT: SUMMARY This case report describes the restoration of the anterior dentition with porcelain laminate veneers. The advances in bonding of porcelain to tooth structure make this treatment a feasible alternative to restore teeth with alteration in shape and position in cases in which the esthetic demand is high. The rationale for various choices in this treatment protocol is detailed with reference to the pertinent literature. Thus, the clinical success of the technique depends on the correct identification of a case for which this treatment is appropriate and the successful execution of the clinical steps involved.
  Operative Dentistry 04/2013;
• Article: Longevity of Direct Restorations in Stress-Bearing Posterior Cavities: A Retrospective Study.

  Y-J Rho, C Namgung, B-H Jin, B-S Lim, B-H Cho
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  ABSTRACT: SUMMARY The aims of this retrospective clinical study were to compare the longevities of direct posterior amalgam restorations (AMs) and resin composite restorations (RCs) that were subjected to occlusal stresses and to investigate variables predictive of their outcome. A total of 269 AMs and RCs filled in Class I and II cavities of posterior teeth were evaluated with Kaplan-Meier survival estimator and multivariate Cox proportional hazard model. Seventy-one retreated restorations were reviewed from dental records. The other 198 restorations still in use were evaluated according to modified US Public Health Service (USPHS) criteria by two investigators. The longevity of RCs was significantly lower than that of AMs (AM = 8.7 years and RC = 5.0 years, p<0.05), especially in molars. The prognostic variables, such as age, restorative material, tooth type, operator group, diagnosis, cavity classification, and gender, affected the longevity of the restorations (multivariate Cox regression analysis, p<0.05). However, among the restorations working in oral cavities, their clinical performance evaluated with modified USPHS criteria showed no statistical difference between both restoratives. In contrast to the short longevity of RCs relative to AMs, the clinical performance of RCs working in oral cavities was observed to be not different from that of AMs. This suggests that once a RC starts to fail, it happens in a rapid progression. As posterior esthetic restorations, RCs must be observed carefully with periodic follow-ups for early detection and timely repair of failures.
  Operative Dentistry 04/2013;
• Article: Effect of a Chlorhexidine-containing Adhesive on Dentin Bond Strength Stability.

  C Sabatini
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  ABSTRACT: SUMMARY Purpose: The present study aimed to investigate a novel adhesive system containing 0.2% chlorhexidine digluconate (CHX) for its ability to improve the stability of the adhesive interface compared with the use of 2% CHX as a therapeutic primer. Furthermore, the study aimed to confirm the inhibitory properties of these CHX concentrations (0.2% and 2.0%) on dentin matrix metalloproteinase activity by gelatin zymography. Methods: Superficial dentin substrate for bonding was obtained from 120 non-carious human molars. A conventional adhesive Peak LC Bond and a CHX-containing adhesive Peak Universal Bond were used either in combination with 35% phosphoric acid (etch-and-rinse approach) or with self-etching primer (self-etch approach) for evaluation of the variables CHX treatment (2.0% therapeutic primer and 0.2% adhesive), adhesive approach (etch-and-rinse and self-etch), and storage time (24 hours and six months). A bonding jig was used to fabricate composite cylinders, which were stored for either 24 hours or six months, after which shear bond strength (SBS) was evaluated using a notched-edge testing device. A three-way analysis of variance and a Student t-test with a significance level of p<0.05 were used to analyze the data. Extracts from concentrated demineralized human dentin powder were subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis and incubated in the presence of 0.2% and 2.0% CHX. Results: No significant effect of CHX treatment, adhesive approach, storage time variables, or their interactions on mean SBS was demonstrated (p<0.05). No significant difference between the control and the CHX-treated groups was detected for either adhesive technique at 24 hours or six months (p<0.05). No significant variation in mean SBS was detected after six months of storage (p<0.05). Zymographic analysis revealed bands of enzymatic activity for the group demineralized with phosphoric acid and complete inhibition of gelatinolytic activity for the groups treated with 0.2% and 2.0% CHX. Conclusions: CHX demonstrated inhibition of dentin proteolytic activity. However, when CHX was incorporated into a commercially available adhesive or used as a therapeutic primer, no difference in bond strength was observed at baseline or after six months of storage relative to the control group without CHX.
  Operative Dentistry 04/2013;
• Article: Interfacial Nanoleakage and Bonding of Self-Adhesive Systems Cured with a Modified-Layering Technique to Dentin of Weakened Roots.

  E Mobarak, R Seyam
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  ABSTRACT: SUMMARY Objective: The purpose of the study was to evaluate the nanoleakage and bond strength of different self adhesive systems cured with a modified-layering technique (MLT) to dentin of weakened roots. Methods: Twenty-one maxillary incisors were decoronated and then root canals were instrumented and obturated with the cold lateral compaction technique. Weakened roots were simulated by flaring root canals until only 1 mm dentin thickness remained. Teeth were distributed into three groups. The canals were backfilled with Vertise Flow (VF group), a self-adhering system, following a modified-layering technique using two light-transmitting posts, sizes 6 and 3. DT Light Post size 2 was cemented using the same material. Remaining roots were prepared and cured in the same way as the VF group. However, in the TS/MF group, Clearfil Tri-S Bond (TS) adhesive and Clearfil Majesty Flow (MF) composite were used, while in the ED/PF group, ED primer II (ED)/Panavia F2.0 (PF) were used. After one week of storage, each root was sectioned to obtain six slices (two slices from each root third: coronal, middle and apical) of 0.9 ± 0.1 mm thickness. Interfacial nanoleakage expression was analyzed using a field emission scanning electron microscope (FEG-SEM), and the micro push-out bond strength (μPOBS) was measured at different root regions. Modes of failure were also determined using SEM. Data were statistically analyzed using two-way analysis of variance with repeated measures and Tukey post hoc test (p≤0.05). Results: With MLT, all adhesive systems showed nanoleakage. For μPOBS, there was a statistically significant effect for adhesive systems (p<0.001) but not for root region (p<0.64) or for their interaction (p=0.99). Tukey post hoc test revealed that the bond strength of the VF group was significantly higher than the TS/MF and ED/PF groups for all root regions. Conclusion: All of the tested self-adhesive systems cured using MLT had slight nanoleakage and were not sensitive to root regional differences. Self-adhering systems had higher bond strength than self-etch adhesives.
  Operative Dentistry 04/2013;
• Article: The Management of Defective Resin Composite Restorations: Current Trends in Dental School Teaching in Japan.

  Cd Lynch, Mikako Hayashi, Ll Seow, Ir Blum, Nhf Wilson
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  ABSTRACT: SUMMARY Aim: The aim of this article is to investigate the contemporary teaching of the management of defective direct resin composite restorations in dental schools in Japan. Methods: An electronic questionnaire relating to the teaching of the management of defective resin composite restorations was developed and e-mailed to 29 dental schools in Japan in 2010. Results: Completed responses were received from 19 of the 29 invited schools (response rate = 66%). Eighteen schools (95%) report that they included the teaching of repair of direct defective resin composite restorations in their dental school programs. Thirteen schools reported that they included both clinical and didactic instruction on the repair of direct resin composite restorations. Fourteen schools did not teach any mechanical roughening of the exposed resin composite restoration surface before undertaking a repair. The most commonly reported treatment was acid etching with phosphoric acid (12 schools). The most commonly taught material for completing repairs was a flowable resin composite (16 schools). Conclusion: The teaching of repair of defective resin composite restorations is well established within many Japanese dental schools, to a greater extent than in some other regions of the world. The impact of this teaching on subsequent clinical practices in Japan should be investigated. Furthermore, it is concluded that there is a need for much stronger leadership in operative and conservative dentistry, ideally at the global level, to resolve differences in key aspects of operative procedures such as repairs.
  Operative Dentistry 04/2013;
• Article: Physical Property Evaluation of Four Composite Materials.

  M Chang, J Dennison, P Yaman
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  ABSTRACT: SUMMARY Purpose: The purpose of this study was to evaluate the physical properties of current formulations of composite resins for polymerization shrinkage, surface hardness, and flexural strength. In addition, a comparison of Knoop and Vickers hardness tests was made to determine if there was a correlation in the precision between the two tests. Materials and Methods: Four composite resin materials were used: Filtek LS (3M-ESPE), Aelite LS (Bisco), Kalore (GC America), and Empress Direct (Ivoclar). Ten samples of each composite (shade Vita A2) were used. Polymerization shrinkage was measured with the Kaman linometer using 2-mm-thick samples, cured for 40 seconds and measured with digital calipers for sample thickness. Surface microhardness samples were prepared (2-mm thick × 12-mm diameter) and sequentially polished using 600-grit silicone carbide paper, 9 μm and 1 μm diamond polishing solutions. After 24 hours of dry storage, Knoop (200 g load, 15 seconds dwell time) and Vickers (500 g load, 15 seconds dwell time) hardness tests were conducted. Flexural strength test samples (25 × 2 × 2 mm) were stored in 100% relative humidity and analyzed using a three-point bending test with an Instron Universal Testing Machine (Instron 5565, Instron Corp) applied at a crosshead speed of 0.75 ± 0.25 mm/min. Maximum load at fracture was recorded. One-way analysis of variance and Tukey multiple comparison tests were used to determine significant differences in physical properties among materials. Results: Filtek LS had significantly lower shrinkage (0.45 [0.39] vol%). Aelite LS demonstrated the greatest Knoop surface hardness (114.55 [8.67] KHN), followed by Filtek LS, Kalore, and Empress Direct (36.59 [1.75] KHN). Vickers surface hardness was significantly greater for Aelite LS (126.88 [6.58] VH), followed by Filtek LS, Kalore, and Empress Direct (44.14 [1.02] VH). Flexural strength (MPa) was significantly higher for Aelite LS and Filtek LS (135.75 [17.35]; 129.42 [9.48]) than for Kalore and Empress Direct (86.84 [9.04]; 92.96 [9.27]). There is a strong correlation between results obtained using Knoop and Vickers hardness tests (r=0.99), although Vickers values were significantly greater for each material. Conclusion: Results suggest that Aelite LS possesses superior hardness and flexural strength, while Filtek LS has significantly less shrinkage compared with the other composites tested.
  Operative Dentistry 04/2013;