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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Polymerization eficiency of dual-polymerized resin cements light-irradiated through ceramics and laboratory-processed resin composite.

The purpose of the study was to determine the influence of light-irradiation through two ceramic and one resin composite materials on the degree of remaining double carbon bonds in 3 dual-polymerized resin cements. After mixing, the cement was inserted into a 0.5 mm deep recess in a silicon mold, covered with one ceramic or resin composite rectangular block and exposed through the block with the light from a halogen polymerization unit for 40 s. Infrared spectroscopic analysis was used to record the degree of remaining double carbon bonds. Light irradiation through 2 mm-thick ceramic and resin composite materials increased the degree of remaining double carbon bonds relative to the direct photopolymerization analogues.

3D-marginal adaptation versus setting shrinkage in light-cured microhybrid resin composites.

PURPOSE: To comparatively evaluate the 3D-marginal adaptation to dentine versus shrinkage strain of two light-cured microhybrid resin composites. METHODS: Dentine cavities (Ø: 2 mm; h: 1 mm; n=2x4) were prepared, filled with a single layer of EsthetX and Premise resin composites, respectively, without any adhesive cavity pre-treatment, and light-cured for 40s at 750 mW/cm2. All the specimens were imaged by computerized X-ray microtomography. Sequential sections (n=11) at 8.09 pixel size were taken at top, middle and bottom sites of each restoration relative to the axial wall and the interfacial micro-void volume fraction (%VF) was calculated. Shrinkage strain (%S) and strain rate (%SR) of the composites were measured by the bonded-disc method (n=4). The results of %VF per material and restoration site were subjected to statistical analysis by 2-way ANOVA and Tukey's test, whereas the results of %S and %SR were analysed by t-test (p=0.05). Regression analysis was performed to determine correlations between %PF and %S, %S(R). RESULTS: The results of %VF at top (t), middle (m) and bottom (b) restoration sites were (%, mean+/-S.D.): EsthetX 0.84+/-0.11 (t), 0.80+/-0.32 (m), 6.74+/-5.12 (b), Premise 0.99+/-0.24 (t), 0.92+/-0.38 (m), 1.72+/-0.97 (b). The results of %S were (%, mean+/-S.D.): EsthetX 2.60+/-0.29, Premise 1.91+/-0.10 and of %SR were (%, mean+/-S.D.): EsthetX 1.47+/-0.04, Premise 1.18+/-0.02. %VF(b) of EsthetX showed the highest values within and between the testing groups (p<0.05). %S and %S(R) values of EsthetX were significantly higher from Premise (p<0.05). Strong positive correlations were documented between %VF(b)-%S (r=0.843) and %VF(b)-%SR (r=0.943). CLINICAL SIGNIFICANCE: The results confirmed a positive correlation between setting shrinkage and interfacial gap volume at bottom sites of light-cured microhybrid composite restoration due to differential shrinkage. Shrinkage strain rate seems to be a more sensitive factor in determining percentage volume of interfacial porosity at bottom restoration sites.

Marginal and internal adaptation of bulk-filled Class I and Cuspal coverage direct resin composite restorations.

This in vitro study compared the marginal and internal adaptation of bulk-filled Class I and cuspal coverage direct resin composite restorations filled with different types of adhesive restorative systems and different thicknesses of bonding agent. Seventy-two intact, caries-free, freshly extracted human molars were randomly divided into 12 groups of six teeth each, according to the type of cavity (Class I [I] or Cuspal Coverage [C]), adhesive restorative system (SE Bond/Clearfil AP-X [SE] or Prime&Bond NT/Spectrum TPH [PB]) and thickness of bonding agent (normal or thick layer) in Class I restorations. Standardized Class I and Cuspal coverage cavities with enamel outer margins were prepared and restored with the corresponding type and thickness of bonding agent and respective resin composite. The resin composite was placed and polymerized in one increment (bulk filling). Dentinal fluid was simulated using 1:3 diluted horse serum and fed into the pulp chamber both during restoration and stressing. In six of the 12 groups, the restorations were subjected to 1.2 million mechanical occlusal cycles (maximum force 49 N; frequency 1.7Hz) and 3,000 simultaneous thermal cycles (5-50-5 degrees C). Marginal adaptation before and after mechanical and thermal stressing was assessed by using the replica technique and quantitative evaluation under SEM at 200x magnification. The teeth were dissected in a mesio-distal direction with a slow rotating diamond disc under water cooling, and the internal adaptation was also assessed by using the replica technique under the conditions described. Statistical evaluation of the continuous margin at the external and internal interface was performed with one-way analysis of variance (ANOVA) and Tukey's Studentized Range (HSD) test (p = 0.05). Even though Cuspal coverage restorations (SE- C: 96.89 +/- 1.83 and PB- C: 97.15 +/- 2.93) exhibited statistically significantly better external adaptation than Class I restorations (SE- I: 63.95 +/- 12.82 and PB- I 64.74 +/- 14.62) before stressing, there was no statistically significant difference after mechanical and thermal stressing (SE- C: 76.35 +/- 18.53 and PB- C: 76.02 +/- 12.49 SE- I: 54.67 +/- 10.82 and PB- I: 59.94 +/- 15.20). After stressing, SE Bond Cuspal coverage restorations (SE- C: 96,72 +/- 3,26) exhibited superior internal adaptation compared to SE Bond Class I restorations (SE- I: 57.83 +/- 12.91). No difference was observed in internal adaptation between Prime&Bond NT Cuspal coverage and Class I restorations (PB- C:36.46 +/- 21.82, PB- I: 38.71 +/- 6.76). In Class I restorations, the increased thickness in bonding did not improve the marginal and internal adaptation either before or after stressing. Bulk-filled direct resin composite Cuspal coverage restorations exhibited marginal adaptation similar to bulk-filled direct resin composite Class I restorations. The internal adaptation of Cuspal coverage SE Bond/Clearfil AP-X restorations was superior to all the other groups tested.

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.

Degree of remaining C=C bonds, polymerization shrinkage and stresses of dual-cured core build-up resin composites.

This study measured the degree of remaining C=C bonds (RDB), linear polymerization shrinkage (LPS) and polymerization stresses (PS) of dual-cured resin composite build-up materials using a variety of light exposure scenarios. Four commercially available materials were used: Bis-Core, FluoroCore, Build-it! and Permalute. The RDB was measured using FTIR spectroscopy, and custom-made devices were used to measure LPS and PS values. Data were obtained using three different modes of photoactivation: NLC (No Light-Curing); ILC (Immediate Light-Curing, where 60 second light-curing was applied at the start of the observation period); and DLC (Delayed Light-Curing, where 60-second light-curing was applied 10 minutes from the start of the observation period). Statistical evaluation of the data at the end of the 13-minute observation period was performed with two-way analysis of variance (ANOVA), Tukey's Studentized Range (HSD) Test (p=0.05) and simple linear regression. Differences in the development of LPS and PS during the 13 minutes were studied using mathematical calculus. Bis-Core presented the highest RDB and Permalute the lowest when ILC was applied, while no differences were found between Build-it! and FluoroCore and NLC and DLC increased RDB for FluoroCore and Permalute compared to ILC; whereas, no differences were noted for Build-it! and Bis-Core. Using DLC, a decrease in RDB was found only for Build-it! FluoroCore and Permalute exhibited a reduction in LPS and PS using NLC relative to ILC. No differences in LPS and PS values were detected for the materials Bis-Core and Build-it! when subjected to NLC or DLC, compared to ILC. Simple linear regression showed that only the two polymerization shrinkage properties studied were highly correlated (LPS-PS r2=0.85). The RDB rate was not correlated with either polymerization shrinkage properties (RDB-LPS r2=0.40; RDB-PS r2=0.57). A study of the evolution of the real-time curves of percentage values of LPS and PS showed that these properties evolved in a similar exponential mode and that, most often, there was a delay in the development of PS.

Clinical effectiveness of two agents on the treatment of tooth cervical hypersensitivity.

PURPOSE: To investigate the desensitizing ability of a one-bottle bonding agent and a glutaraldehyde-based HEMA formulation on sensitive tooth cervical areas for a period up to 9 months. METHODS: The sample consisted of 40 patients with cervical hypersensitivity. Three sensitive teeth per patient were treated; one received One-Step (one-bottle bonding agent), the other Gluma Desensitizer (glutaraldehyde-based agent) and the third distilled water (control group). The hypersensitivity level was determined before, immediately after the desensitizing session, at 8 weeks, and 9 months post-treatment. Measurements of sensitivity were determined by the patient's response to tactile and air-blast stimuli. A verbal rating scale was used and scored as follows: 0, no discomfort; 1, discomfort but no severe pain; 2, severe pain during simulation; 3, severe pain after simulation. The results were subjected to statistical analysis by Kruskal-Wallis test (a=0.05). RESULTS: Both treatment procedures resulted in reduction of hypersensitivity to both stimuli, for up to 9 months. No significant differences were recorded between One-Step and Gluma Desensitizer at immediate and 8-week examinations, whereas Gluma Desensitizer produced lower hypersensitivity than One-Step at the 9-month assessment. In general, a lower level of reduction was found for the 9-month interval compared to the 8-week hypersensitivity score for both agents tested. A placebo effect was observed with water treatment, ranging from 4.7 to 27.5% reduction of hypersensitivity.

Colour stability of tooth-coloured restorative materials.

The colour stability of the surface and in-depth (2 mm) layer of two resin composites, a laboratory second-generation resin composite and a compomer were evaluated after 24 and 360 hours of water aging under dark and UV light conditions. The influence of various polymerization techniques on color changes was also evaluated. Color differences (deltaE*) showed higher color changes under UV light exposure than under dark storage, both at 24- and 360-hour evaluations. Color changes were statistically higher at the 360-hour assessment, in both conditions of maintenance. Compomer was the least color stable of the materials tested. Additional polymerization significantly decreased the colour change of both composite resins.

In vivo vs in vitro anticariogenic behavior of glass-ionomer and resin composite restorative materials.

OBJECTIVE: To evaluate the in vivo vs the in vitro anticariogenic potential of glass-ionomer and resin composite restoratives, utilizing a standardized interfacial gap model. METHODS: (a) In vitro study. Box shaped cavities were prepared at the buccal surfaces of extracted premolars limited to enamel. The incisal cavity walls received no treatment and were covered with 40 microm-thick metal spacers. The cavities were restored with a glass-ionomer (Ketac-Fil, n=8) and a fluoride-free resin composite (Scotchbond MP Plus/Z100, n=8). After 4 weeks immersion in an acidic gel (pH 4), thin sections were produced and examined under polarized-light microscopy.(b) In vivo study. Four low caries activity volunteers, with first four premolars, each planned to be extracted for orthodontic reasons, participated in the study. Cavities were prepared as before and filled contralaterally per patient with glass-ionomer (n=8) and resin composite (n=8). After 6 months in vivo, the teeth were extracted, sectioned and investigated by polarized-light microscopy, Raman microspectroscopy and SEM-EDS X-ray microanalysis. Unpaired t-test (lesion dimensions) and one-way ANOVA and Newman-Keuls tests (Ca, P wt%, Ca/P ratios) were used to identify statistically significant differences in lesion analysis (alpha=0.05). RESULTS: (a) In vitro study. All restorations developed lesions at incisal and cervical margins. At gap-free regions glass-ionomers showed reduced lesion dimensions compared to those of composites (p<0.05). At regions with gaps, no significant differences were found in lesion depth between the restorative groups tested. Lesion length was increased in composite, and decreased in glass-ionomer, whereas lesion depth in both restorative groups was increased in comparison to gap-free regions (p<0.05).(b) In vivo study. No lesions were observed at gap-free regions. At gap regions, 75.5% of glass-ionomer and 62.5% of composite restorations developed lesions. The lesion dimensions were significantly greater in glass-ionomer (p<0.05). A reduction in PO4(3-), CO3(2-), Ca and P was found in lesions compared to intact tissues. No F was detected and no CaF2 lattice vibrations were found at the enamel margins facing the gap adjacent to glass-ionomers. SIGNIFICANCE: In the presence of a standardized interfacial gap, no preventive effect was exerted in vivo from the glass-ionomer to protect the adjacent enamel wall from secondary caries attack. The lack of any correlation between the in vivo and in vitro models tested implies that artificial caries experiments have a negligible clinical relevance in predicting the in vivo effect.