A 2-Year Randomized Clinical Trial of Three Bonding Techniques in Non-Carious Cervical Lesions.

Background and objective: The aim of this randomized split-mouth study-controlled clinical trial was to compare the 2-year clinical performance of resin composite restorations placed at non-caries cervical lesions (NCCL) with one-step self-etch, total-etch, and selective enamel etch and self-etch adhesive techniques. Materials and methods: Thirty-two patients received three resin composite restorations each at NCCLs (Tetric EvoCeram/Ivoclar/Vivadent), bonded with a total-etch adhesive agent (ExciTE F/Ivoclar/Vivadent) and a self-etch (AdheSE One F/Ivoclar/Vivadent) without and with selective enamel etching. All restorations were evaluated by two examiners at baseline, 6-, 12-, 18-, and 24-months with FDI clinical criteria (post-operation regarding retention, caries occurrence, marginal adaptation, and marginal staining). A logistic regression analysis, a Cohen's kappa statistic, a multifactorial analysis, and X2 were performed with generalized estimating equations. Results: After 2 years, the retention rate was 86.8% for total etch, 92.26% for self-etch, and 93.63% for selective enamel etching and self-etch. No caries was detected on the restorations. Concerning marginal adaptation, the clinically perfect restorations were 26.9% for the total-etch technique, 16% for self-etch, and 25.9% for selective enamel etch and self-etch. The logistic regression model revealed that only time reduced the probability of perfect marginal adaptation. Conclusions: All three adhesive strategies provided restorations with no significant differences in the retention rate or marginal adaptation, whereas the total etch yielded better performance for marginal staining. All restorations were assessed as clinically acceptable after 2 years.

Sustainable Distance Online Educational Process for Dental Students during COVID-19 Pandemic.

In this study, we evaluated the perception of distance online learning in undergraduate dental students in two different European countries during the second lockdown of the COVID-19 pandemic to explore sustainable undergraduate educational and examination e-learning forms. Dental students from Dental school of Athens, National and Kapodistrian university of Athens (N1_3rd preclinical year = 131, N2_4th clinical year = 119) and Dental school of Copenhagen (3rd preclinical year N3 = 85) completed the mixed-designed Dental e-Learning process Questionnaire (DeLQ) distributed in a google form. Responses to closed-ended questions were collected on a five-point Likert scale. Descriptive statistics were applied, and non-parametric Kruskal-Wallis tests were used to examine student groups. N1 (90% strongly agree) students reported that "e-learning is a suitable education method for theory in dentistry" at a significant level and more often than N2 (43% strongly disagree). N1 and N2 students strongly agreed that they preferred face-to-face teaching rather than distance e-learning. A relatively low number of N1 (31%) students believed that e-learning prepares them sufficiently for their practical training while none of the (0%) N2 cohort agreed. A low percentage of students in both years (N1 = 31%, N2 = 23%) believed that e-learning prepared them for their exams. Additionally, N1 = 60% and N2 = 66% preferred hybrid learning. Only 26% (N1) and 19.5% (N2) desired e-learning to continue after the COVID-19 pandemic. Nearly half of the participants believed the online exam model to be unreliable (N1 = 49%, N2 = 43%). Overall, students considered distance e-learning as an educational method applicable only to theoretical lessons. However, the lack of physical communication and interaction in distance learning led students to prefer a blended method. Students of the two faculties seemed to agree on many points, but there were also specific differences attributable to the differences in the programs and educational culture of the two countries.

Effect of decontamination procedures on marginal and internal adaptation in saliva-contaminated composite resin restorations.

The aim of the present study was to evaluate the effect of natural saliva contamination of dentin on the adaptation of composite resin restorations as well as the efficacy of various decontamination techniques. A total of 120 human molars and premolars were randomly distributed into 6 groups (n = 20). Standardized dentin cavities were prepared and restored with composite resin after 1 of 6 different surface treatments, which included a 2-step etch-and-rinse adhesive: 1, dentin etching, adhesive application following the manufacturer's instructions (control), light curing; 2, dentin etching, saliva contamination, air drying, adhesive application, light curing; 3, dentin etching, saliva contamination, water rinsing, air drying, adhesive application, light curing; 4, dentin etching, adhesive application, light curing, saliva contamination, air drying; 5, dentin etching, adhesive application, light curing, saliva contamination, water rinsing, air drying; or 6, dentin etching, adhesive application, light curing, saliva contamination, water rinsing, air drying, adhesive reapplication. The adaptation was evaluated at the top surface and at depths of 0.5 and 1.0 mm by measuring the length of the debonded margin and calculating its percentage relative to the cavity perimeter (%DM). The internal adaptation was evaluated by measuring the width of the maximum marginal gap (MMG). Inferior adaptation was observed after saliva contamination took place. Group 1 presented the most satisfactory adaptation at the top surface, whereas groups 4 and 5 had the highest %DM and greatest MMG at all surfaces (P < 0.05). The %DM and MMG values in groups 2, 3, and 6 were not significantly different from those of group 1 or each other. Saliva contamination after adhesive application (groups 4 and 5) resulted in deterioration of marginal and internal adaptation. Reapplication of the adhesive restored adaptation, as evidenced by the %DM and MMG values in group 6.

Online videos: The hidden curriculum.

INTRODUCTION: Dental undergraduates will access the Internet searching for learning materials to complement their training; however, open access content is not generally recommended by dental schools. This study aimed to evaluate how dental students are using online video content. MATERIALS AND METHODS: Students from eight Universities (Athens, Birmingham, Brescia, Cardiff, Melbourne, Paris, Sao Paulo and Valdivia) representing three continents were invited to complete a survey on their access and learning from online videos. RESULTS: International students behave similarly when studying dental content online. Of 515 respondents, 94.6% use the Internet as a learning tool. It was observed that videos are not frequently recommended during didactic lectures (9.6%). But many students (79.9%) will use YouTube for their learning which includes clinical procedures. Students will check online content before performing procedures for the first time (74.8%), to understand what was explained in class (65.9%) or read in books (59.5%), to relearn clinical techniques (64.7%) and to visualise rare procedures (49.8%). More than half of the students do not fully trust the accuracy or the reliability of online content. This does not prevent students from watching and sharing dental videos with classmates (64.4%). The content watched is not shared with teachers (23.3%) even when it contradicts what was learnt in the school (38.2%). CONCLUSION: This study concludes that students regularly integrate open access digital resources into learning portfolios but are hesitant to inform their teachers about their viewing habits. Students wish to receive critical skills on how to evaluate the material they encounter outside their traditional learning space.

Color comparison of three layered resin composite systems with three shade guides.

OBJECTIVE: To investigate the color difference using both ΔE*ab and CIEDE2000 formulas of all combinations of all enamel and dentin shades of three different composite systems with three different shade guides, to compare the coverage error (CE) of the shade guides for each composite and to investigate whether coverage error is affected by enamel shade layer thickness (0.5 vs 1 mm). MATERIALS AND METHODS: Disk specimens from all enamel and dentin shades of Essentia, Enamel Plus HRi, and IPS Empress Direct composites were fabricated. Color measurements were performed for all enamel-dentin combinations and for two thicknesses per enamel shade: 0.5 and 1 mm. Color was measured for three shade guides: Vitapan Classical, 3DMaster, and Ivoclar. Minimum color difference between layered composites and shade tabs, closest shade tab match and CE of all shade guides were calculated for all composite shade combinations. RESULTS: In most cases, the closest match was a mismatch. CE of 3DMaster was significantly lower for IPS Empress Direct and Enamel Plus HRi at 0.5 mm enamel thickness. Shade guides exhibited higher lightness values compared to composites and composites lower chroma values compared to shade guides. CONCLUSIONS: Shade guides do not match well to the layered composites. 3DMaster performed better than the other two shade guides, in most cases.

Comparative Evaluation of Chair-Side Saliva Tests According to Current Dental Status in Adult Patient.

BACKGROUND: this cross-sectional study evaluated the correlation of commercial chair-side saliva tests with caries status in adults. METHODS: teeth in 87 adults (20-40 years old) were clinically examined for carious lesions according to International Caries Detection and Assessment System (ICDAS) criteria. The Decayed-Missing-Filling-Tooth (DMFT) and Decayed-Missing-Filling-Surface (DMFS) indexes at D1 (lesions 1-6 according to ICDAS criteria) and D3 (lesions 4-6 according to ICDAS criteria threshold and the number of active lesions, according to the Lesion Activity Assessment (LAA)) criteria were measured. The saliva parameters measured by chair-side tests were stimulated and non-stimulated saliva flow rate, saliva consistency, saliva pH, saliva buffer capacity, and lactic acid production. The statistical analyses performed were Student t-test and Mann-Whitney U test at a = 0.05 significant level. RESULTS: the low resting saliva pH was related to a high value of DMFT (D1) index (p = 0.007). CONCLUSIONS: among the saliva parameters measured, the values of low resting pH are associated with increased DMFT at threshold D1. None of the chair-side available saliva tests evaluated can accurately underline the tooth carious status.

Evaluation of reliability and validity of three dental color-matching devices.

PURPOSE: To assess the repeatability and accuracy of three dental color-matching devices under standardized and freehand measurement conditions. MATERIALS AND METHODS: Two shade guides (Vita Classical A1-D4, Vita; and Vita Toothguide 3D-Master, Vita), and three color-matching devices (Easyshade, Vita; SpectroShade, MHT Optic Research; and ShadeVision, X-Rite) were used. Five shade tabs were selected from the Vita Classical A1-D4 (A2, A3.5, B1, C4, D3), and five from the Vita Toothguide 3D-Master (1M1, 2R1.5, 3M2, 4L2.5, 5M3) shade guides. Each shade tab was recorded 15 continuous, repeated times with each device under two different measurement conditions (standardized, and freehand). Both qualitative (color shade) and quantitative (L, a, and b) color characteristics were recorded. The color difference (ΔE) of each recorded value with the known values of the shade tab was calculated. The repeatability of each device was evaluated by the coefficient of variance. The accuracy of each device was determined by comparing the recorded values with the known values of the reference shade tab (one sample t test; α = 0.05). The agreement between the recorded shade and the reference shade tab was calculated. The influence of the parameters (devices and conditions) on the parameter ΔE was investigated (two-way ANOVA). Comparison of the devices was performed with Bonferroni pairwise post-hoc analysis. RESULTS: Under standardized conditions, repeatability of all three devices was very good, except for ShadeVision with Vita Classical A1-D4. Accuracy ranged from good to fair, depending on the device and the shade guide. Under freehand conditions, repeatability and accuracy for Easyshade and ShadeVision were negatively influenced, but not for SpectroShade, regardless of the shade guide. CONCLUSION: Based on the total of the color parameters assessed per device, SpectroShade was the most reliable of the three color-matching devices studied.

Effectiveness of an in-office arginine-calcium carbonate paste on dentine hypersensitivity in periodontitis patients: a double-blind, randomized controlled trial.

AIM: The aim of this single-centre, two-cell, double-blind, randomized controlled clinical study was to evaluate the effectiveness of an in-office desensitizing paste containing 8% arginine and calcium carbonate in providing relief on dentine hypersensitivity immediately after scaling and root planing and its sustained relief over a 6-week period. MATERIALS AND METHODS: Fifty periodontitis subjects presenting hypersensitivity were subjected to scaling and root planing and in-office application of either 8% arginine and calcium carbonate desensitizing paste (25 subjects, test group) or fluoride-free prophylaxis paste (25 subjects, control group). Air-blast hypersensitivity was assessed using Schiff and Visual Analogue (VAS) scales at baseline, post-scaling, post-application, 2, 4 and 6 weeks. RESULTS: At all evaluation times, the test group presented significant % reduction in hypersensitivity relative to post-scaling (t-test, p < 0.05) (Schiff - Test: 57, 58.6, 60.2, 68; CONTROL: 28.6, 22.2, 23, 23) (VAS - Test: 60, 55.6, 60.1, 68.4; CONTROL: 25.9, 18.2, 20.6, 22.7) and significant % hypersensitivity difference relative to control (ancova, p < 0.05) (Schiff: 38.9, 45.9, 47.4, 57.7; VAS: 49.1, 48.9, 52.6, 61). CONCLUSION: The single in-office application of the 8% arginine-calcium carbonate desensitizing paste after scaling and root planing provided significant immediate reduction in dentine hypersensitivity, which sustained over a 6-week period.

Change of optical properties of contemporary polychromatic resin composites after light curing and finishing.

OBJECTIVES: To compare color and translucency changes after light curing and finishing in various shades of five contemporary resin composites. METHODS: Light and dark (A1 & A4 or equivalents), enamel (e) and dentin (d), shades were selected from the resin composites Enamel Plus HRi (Micerium), Miris 2 (Coltene), IPS Empress Direct (Ivoclar), Filtek Supreme (3M ESPE) and TPH Spectum (Densply). Ten disc-shaped samples (depth = 10 mm, thickness = 1 mm) per material and shade were fabricated. Three colorimetric readings, over white and black background, according to the CIELab system were taken before and after light polymerization and after finishing with wet carbide papers. Color (ΔE) and translucency (ΔTP) differences were calculated. Results were analyzed by ANOVA, post-hoc Scheffe's test and linear regression analysis. RESULTS: Polymerization provided a wide range of color change, ranging from 1.36 (Hri/UD1) to 8.07 (Miris/WB). Translucency increased in all groups, except Miris/NT. Translucency change varied from -0.4 (Miris/NT) to 8.88 (Hri/UE3). After finishing, ΔE ranged from 0.58 (Hri/ UD4) to 3.41 (Miris/NT). ΔE was significantly positively correlated with ΔL, Δb after curing and with ΔL, Δa, ΔTP after finishing. CONCLUSIONS: Polymerization caused remarkable color and translucency changes, which were product and shade dependent. Thirteen out of 18 of the tested resin composites exhibited clinically perceptible (ΔE>2.6) color change after light curing and 2 out of 18 after finishing. CLINICAL SIGNIFICANCE: Shade matching with non-polymerized resin composite may be erroneous.

Guidance on posterior resin composites: Academy of Operative Dentistry - European Section.

There have been many developments in operative dentistry in recent years, including a progressive shift to the use of resin composites, rather than dental amalgam, in the restoration of posterior teeth. This shift allows the adoption of minimal intervention approaches, thereby helping to conserve and preserve remaining tooth tissues and structures. This paper presents the position of the Academy of Operative Dentistry European Section (AODES) in relation to posterior resin composites. The AODES considers adhesively bonded resin composites of suitable composition and properties to be the "material of choice" for use in direct minimal intervention approaches to the restoration of posterior teeth. In so doing, the AODES emphasises the importance of the practice of evidence-based minimal intervention dentistry, including the use of refurbishment and repair techniques to extend the longevity of restorations. Guidance, based on best available evidence, has been made in relation to certain aspects of resin composite placement techniques in posterior teeth.

In vitro assessment of tooth color alteration by two different types of endodontic irrigants.

AIM: The purpose of this study was to assess in vitro the tooth color alterations associated with two commonly used endodontic irrigants, the chlorhexidine gluconate (CHX) and the sodium hypochlorite (NaOCl) up to 15 days post-treatment. Additionally, the possible influence of endodontic access preparation on tooth color was investigated. MATERIALS AND METHODS: Thirty intact human anterior teeth were used. Black adhesive tape with a 4 mm diameter window was used to standardize the enamel surface intended for color analysis. After the access cavity, preparation and the initial root canal negotiation with stainless steel hand files, the root canal shaping was completed with rotary nickel-titanium files. The teeth were divided into three groups (n = 10). Conventional syringe irrigation was performed with one irrigant for each group. The enamel surfaces were colorimetrically evaluated before access cavity, after cavity preparation and at 1, 3, 7 and 15 days post-treatment. The CIE color parameters (L*, a*, b*) were recorded and averaged for each material and the corresponding color differences (ΔE) were calculated and statistically analyzed. RESULTS: The most significant factor in tooth color alteration, during the endodontic treatment, was the access preparation. CHX and NaOCl caused tooth color changes comparable with the saline. CHX and NaOCl did not increase the tooth color changes relative to the values induced by the access preparation. CONCLUSION: The two endodontic irrigants were not able to induce tooth color alteration to a greater extent than the access preparation. CLINICAL SIGNIFICANCE: Chlorhexidine and NaOCl cannot be considered as discoloring endodontic materials. The most contributing factor in tooth color alteration during endodontic treatment in the anterior teeth is access preparation.

Mechanical properties of contemporary composite resins and their interrelations.

OBJECTIVE: To characterize a spectrum of mechanical properties of four representative types of modern dental resin composites and to investigate possible interrelations. METHODS: Four composite resins were used, a microhybrid (Filtek Z-250), a nanofill (Filtek Ultimate), a nanohybrid (Majesty Posterior) and an ormocer (Admira). The mechanical properties investigated were Flexural Modulus and Flexural Strength (three point bending), Brinell Hardness, Impact Strength, mode I and mode II fracture toughness employing SENB and Brazilian tests and Work of Fracture. Fractographic analysis was carried out in an SEM to determine the origin of fracture for specimens subjected to SENB, Brazilian and Impact Strength testing. The results were statistically analyzed employing ANOVA and Tukey post hoc test (a=0.05) while Pearson correlation was applied among the mechanical properties. RESULTS: Significant differences were found between the mechanical properties of materials tested apart from mode I fracture toughness measured by Brazilian test. The latter significantly underestimated the mode I fracture toughness due to analytical limitations and thus its validity is questionable. Fractography revealed that the origin of fracture is located at notches for fracture toughness tests and contact surface with pendulum for Impact Strength testing. Pearson analysis illustrated a strong correlation between modulus of elasticity and hardness (r=0.87) and a weak negative correlation between Work of Fracture and Flexural Modulus (r=-0.46) and Work of Fracture and Hardness (r=-0.44). Weak correlations were also allocated between Flexural Modulus and Flexural Strength (r=0.40), Flexural Strength and Hardness (r=0.39), and Impact Strength and Hardness (r=0.40). SIGNIFICANCE: Since the four types of dental resin composite tested exhibited large differences among their mechanical properties differences in their clinical performance is also anticipated.

Change of optical properties of contemporary resin composites after one week and one month water ageing.

OBJECTIVES: To compare color and translucency changes after water ageing for one-week and one-month in light and dark shades of contemporary polychromatic resin composites. METHODS: Enamel (e) and dentine (d), light and dark (A1 and A4 or equivalents) shades were selected from the composites Enamel-Plus HRi/Micerium, Miris-2/Coltene, IPS Empress-Direct/Ivoclar and Filtek-Supreme/3M ESPE and light and dark shades from the TPH-Spectum/Densply monochromatic composite. Five disks (d = 10mm, h = 1mm) per material, enamel/dentine and light/dark shade were prepared. A colorimetric evaluation, over white and black background, according to the CIELab system was performed just after preparation and after one-week and one-month dark water-storage at 37°C. Color (ΔEab) and translucency (ΔTP) differences were calculated. Results were analysed by ANOVA and Scheffe's test, paired t-test and linear regression analysis (a = 0.05). RESULTS: One-week water ageing provided a wide range of ΔEab values (0.79 Filtek(e)/D2 to 5.19 Filtek(d)/A1) and ΔTP values (-2.74 Hri/UD1 to 1.03 TPH/A1). After one-month water ageing ΔEab ranged from 1.09 Filtek(e)/D2 to 7.94 Filtek(d)/A1 and ΔTP values from -2.71Hri/UD1 to 1.07 Filtek(d)/A4. Significant changes in ΔEab between one-week and one-month water ageing were noted for Filtek and Miris dentine and Miris light enamel shades. As for ΔTP, significant difference was recorded only for IPS(e)/A4. ΔEab was significantly correlated with ΔL, Δα, Δb and ΔTP after one-week and with ΔL and Δα after one-month ageing. CONCLUSIONS: Water ageing caused remarkable color changes, which were material and shade depended. Thirteen out of eighteen of the tested composites exhibited clinically perceptible (ΔEab>2.6) color changes even after short water ageing period.

Evaluation of a new fluorescence-based device in the detection of incipient occlusal caries lesions.

The aim of this in vitro study was to evaluate the performance of various contemporary detection tools at incipient occlusal caries. Thirty eight freshly extracted posterior teeth with non-cavitated occlusal caries were subjected to clinical examination and coding according to ICDAS criteria (n = 38). Standardized fluorescence images were taken with VistaProof (Dürr Dental, Bietigheim-Bissingen, Germany). Furthermore, the teeth were calculated with a laser fluorescence pen device (DIAGNOdent pen, Kavo, Biberach, Germany). In all detection methods, assessment of caries was performed twice (with 1-week interval) by two calibrated examiners. Finally, the caries lesions were validated in tooth sections by histological examination. The intra-examiner and inter-examiner kappa coefficient, sensitivity, and specificity were determined for all detection methods at enamel lesions (D1 threshold). Degrees of agreement of each method with the histological status were calculated using receiver operating characteristic statistics and the area under curve (Az values). The kappa intra-examiner/inter-examiner coefficient values (mean ± SD) were 0.74 ± 0.04/0.73 ± 0.07, 0.87 ± 0.04/0.82 ± 0.07, and 0.91 ± 0.06/0.83 ± 0.08 for clinical examination, DIAGNOdent pen, and VistaProof, respectively. The sensitivity for ICDAS was 0.80-0.86, for DIAGNOdent pen was 0.66-0.75, and for the VistaProof device was 0.97. The specificity for all the detection methods were 0.5 (0.02-0.99). The accuracy value for ICDAS was 0.76-0.81, for DIAGNOdent pen 0.66-0.71, and for the VistaProof device 0.92-0.95. The Az values (mean ± SD) were 0.431 ± 0.187, 0.583 ± 0.215, and 0.486 ± 0.207 for ICDAS, DIAGNOdent pen, and VistaProof examination, respectively. No significant differences in Az values were noted among the methods. All detection methods were presented with high inter-examiner and intra-examiner agreement. The new VistaProof device showed the best sensitivity, while DIAGNOdent pen demonstrated the worst one. Specificities were the same for all detection methods. Moreover, they presented the same performance in detection of incipient occlusal caries.

Clinical effectiveness of a desensitizing system on dentin hypersensitivity in periodontitis patients.

PURPOSE: To evaluate the efficacy of the DenShield desensitizing system, based on calcium sodium phosphosilicate, in the hypersensitivity reduction for a 6-month period in periodontitis patients previously subjected to periodontal treatment and to compare the combination of the in-office paste and at-home dentifrice use to the at-home dentifrice use alone. METHODS: A total of 248 teeth (eight teeth in each subject) in 31 periodontitis patients (mean age 48 +/- 8 years) previously subjected to periodontal treatment were studied. 193 (77.8%) teeth had been treated with phase I periodontal treatment alone (non-surgical treatment) and 55 (22.2%) had been additionally subjected to periodontal surgery. Periodontal clinical parameters were recorded for each subject. Hypersensitivity was assessed by tactile and air-blast stimuli. The hypersensitive teeth of each of two quadrants in each subject were randomly assigned with split-mouth design to in-office application of DenShield Starter paste (four teeth) or placebo (distilled water) (four teeth). After the in-office application each patient used the DenShield dentifrices (Builder and Saver) for 6 months. The final evaluation was at 6 months. RESULTS: The prevalence and the degree of baseline hypersensitivity was significantly higher for the surgically than the non-surgically-treated teeth (83.6% versus 68.4%) and it was greater in teeth with attachment loss. The dentin hypersensitivity observed after periodontal treatment was significantly reduced in periodontitis patients who used the DenShield system for 6 months. There was no difference in hypersensitivity reduction between the additional in-office application of the DenShield and the at-home use of the DenShield dentifrices alone.

The influence of matrix type on the proximal contact in Class II resin composite restorations.

PURPOSE: This in vitro study evaluated the efficiency of various types of matrices in reconstructing the proximal contact area in Class II resin composite restorations. MATERIALS AND METHODS: Standardized MO cavities were prepared on artificial molars of a manikin model. Resin composite (Spectrum TPH-3) restorations were placed using the following matrices (n=10): a) circumferential straight metal matrix with Tofflemire retainer-A, b) circumferential pre-contoured metal matrix system-B (Adapt SuperCap), c) circumferential pre-contoured transparent matrix system-C (Adapt SuperCap) and d) sectional pre-contoured metal matrix system-D (Palodent). After completion of each restoration, the manikin model was fixed on a tension-meter apparatus and an orthodontic wire was used to assess the contact tightness (CT), length of contact arc (LCA) and position of contact point relative to LCA% (PCP). The same measurements were performed on a group of intact molars (REF). The results were statistically analyzed with one-way ANOVA and the Tukey test, as well as the unpaired t-test (alpha=0.05). RESULTS: Matrix D provided the highest CT with the highest LCA, which presented a statistical difference relative to the intact tooth. Restorations with matrix B provided higher LCA than those with matrices A and C, which were found to be comparable to that of an intact tooth. The contact points (PCP) of the filled teeth were located more cervically in matrix D relative to the intact tooth (lower PCP), whereas matrices A, B and C showed more occlusal location (higher PCP). CONCLUSIONS: Differences were noted among all the matrices evaluated and none was proven sufficient to reconstruct the proximal contact characteristics of an intact tooth.

Marginal behaviour of self-etch adhesive/composite and combined amalgam-composite restorations.

The aim of this study was to compare the marginal and internal adaptation in self-etching adhesive (SEA)/composite restorations with combined amalgam-resin-based composite restorations in the proximal box with and without bonding agent beneath amalgam both before and after load-cycling. Class II restorations, were manufactured as following a) Bonding agent (Clearfil Liner Bond 2V, Kuraray) beneath amalgam (Tytin, SDS Kerr) and resin-based composite (Clearfil APX, Kuraray) with SEA, b) Amalgam without bonding agent and resin-based composite with SEA and c) Resin-based composite with SEA. Each group divided into two equal subgroups (n=8). Marginal and internal adaptation of first subgroup evaluated after 7-day water storage and of the second after load-cycling in chewing simulator for 1.2 x 10(6) cycles. Marginal and internal adaptation at cervical and amalgam-composite sites evaluated by videomicroscope and ranked as "excellent"/"non-excellent". Slices of restorations examined under optical microscope to determine the quality of bonding layer. Defects in cervical adaptation observed in the three restorative techniques examined prior loading. Amalgam-composite combination in proximal surface provided comparable marginal and internal adaptation results at cervical wall, to self-etching-composite combination. Portion (25-37.5%) of amalgam-resin-based composite interfaces in proximal box presented no perfect sealing. The application of bonding agent beneath amalgam resulted in relatively inferior cervical adaptation. Loading resulted in fewer excellent restorations in all three restorative techniques but not in a statistically significant level.

Curing efficiency of high-intensity light-emitting diode (LED) devices.

We evaluated the curing efficiency of 4 high-intensity light-emitting diode (LED) devices by assessing percentage of residual C=C (%RDB), surface microhardness (SM), depth of cure (DC), percentage of linear shrinkage-strain (%LS), and percentage of wall-to-wall contraction (%WWC). The light-curing units tested were a QTH light, the Elipar TriLight (3M/ESPE), and 4 LED devices - the Allegro (Denmat), the Bluephase (Ivoclar/Vivadent), the FreeLight2 (3M/ESPE), and The Cure TC-01 (Spring Health Products). The %RDB was measured by microFTIR spectroscopy. Microhardness measurements (Vickers) were performed at the surface (H0) and at depths of 3 mm (H3) and 5 mm (H5) of cylindrical specimens. Depth of cure was expressed as the ratio of microhardness at each depth, relative to the corresponding surface value (H3/H0 and H5/H0). The bonded disc method was used to evaluate %LS. For the %WWC evaluation, cylindrical resin restorations were imaged by high resolution micro-CT and the %WWC was calculated at depths of 0 mm and 2 mm. There were no statistical differences among the LEDs in %RDB or %LS. The Bluephase and Allegro had the highest SM values. As compared with the other LEDs, the Bluephase and The Cure TC-01 had lower values for depth of cure at depths of 3 mm and 5 mm. There were no significant differences in %WWC among the LEDs at either depth, and the QTH had the lowest %WWC at both depths.

Effect of tooth-bleaching methods on gloss and color of resin composites.

OBJECTIVES: The purpose of the study was to evaluate gloss and color changes of resin composites after exposure to different bleaching agents. METHODS: Products used, were: Nite White ACP (10% carbamide peroxide gel), Crest Classic and Supreme Whitestrip (6.5% and 14% hydrogen peroxide strips, accordingly). A hybrid (Herculite XRV) and a nanohybrid (Premise) resin composite were exposed to the bleaching agents. Twenty-four disk-shaped specimens per composite were subjected to bleaching by each of the agents (n=8) for up to 2 weeks. Color changes using CIE-L*a*b* system (50:50% acceptability threshold: ΔE*=3.3) were recorded after 1 and 2 weeks bleaching cycles relative to baseline measurements. In addition, gloss measurements (in gloss units) were performed at the same bleaching intervals and gloss changes were calculated. RESULTS: All bleaching agents tested provided decrease in gloss of both composites after 2-week bleaching (p<0.05). No differences were detected among the three bleaching regimens, for up to 2-week application, in terms of color and gloss changes on both composites. After the 2-week bleaching period, hybrid composite presented higher gloss reduction (%) than nanohybrid regardless of the bleaching agent (p<0.05). Color change (ΔE*) was lower than 3.3 for all composite-bleaching agent combinations. After 1- and 2-week bleaching time, the nanohybrid composite provided higher color change than the hybrid under all bleaching procedures (p<0.05). No strong correlation was proved between color (ΔE*) and gloss changes caused by bleaching treatments. CONCLUSIONS: After 2-week bleaching cycles, composites showed significant gloss reduction (p<0.05). Color alteration was below the 50:50% acceptability threshold (ΔE*<3.3) and it was product-depended. There was no significant difference in color and gloss changes between the evaluated bleaching strips and 10% carbamide peroxide gel.

Setting characteristics and cavity adaptation of low-shrinking resin composites.

OBJECTIVES: The aim of this study was to evaluate the setting characteristics of low-shrinking resin composites and examine the possible interactions with curing efficiency and marginal adaptation in dentin cavities. METHODS: The materials tested were Ceram X Mono/CM, Premise/PR, Clearfil Majesty/CM, ELS/EL, and Filtek Silorane/FS. Polymerization shrinkage strain (%S), strain rate (%S(r)) and time at maximum strain rate (t(max)) were measured using the bonded disk method. Curing efficiency was measured on the top and bottom surfaces of composites with ATR-FTIR spectroscopy. Marginal adaptation was measured in unbonded (%VVF) and bonded (%XVF) specimens by computerized X-ray microtomography (micro-XCT). The % linear length of the interfacial gaps along the cavity margins (%LD) and the maximum gap width (WD(max)) were calculated under optical microscopy on sectioned specimens. Statistical analysis was performed with one- and two-way ANOVA, Bonferroni's post hoc test and Pearson's correlation coefficient. RESULTS: The %S values ranged from 1.34% (FS) to 2.29% (CX), while %S(r) ranged from 0.06%s(-1) (FS) to 0.15%s(-1) (CX). %VVF values extended from 1.9% (FS) to 5.3% (CX) and for %XVF from 1.98% (FS) to 3.35% (CX). The values for %LD ranged from 36.52% (FS) to 81.28% (CX). Linear regression showed strong positive correlation for %S(r) and t(max) with %VVF (r(2)=0.884 and r(2)=0.927) and also for %S(r) and t(max) with %LD (r(2)=0.823 and r(2)=0.869). SIGNIFICANCE: %S(r) and t(max) are more representative than %S in determining the setting pattern of the materials and are strongly correlated to marginal adaptation. The silorane material showed better behavior than the dimethacrylate materials in setting shrinkage and marginal adaptation.