Deborah S. Cobb

In vitro temperature change at the dentin/pulpal interface by using conventional visible light versus argon laser.

The argon laser has been promoted as a competing technology to multi‐wavelength visible light as a curing source for dental restorative resins. However, the comparative thermal risk to the pulp between these two sources of light energy requires determination. The objective of this study is to compare the temperature induced at the dentin‐pulpal interface between the argon laser and visible light curing unit at a variety of exposure regimens and conditions.

Association between microtensile bond strength and leakage in the indirect resin composite/dentin adhesively bonded joint.

PURPOSE Develop a methodology to correlate microtensile bond strength (microTBS) and leakage within the same site of a specimen and evaluate the predominate debond and leakage pathways. MATERIALS AND METHODS A Class II (MO) slot cavity was prepared in 37 extracted human molars and restored with indirect resin composite restorations. The restored teeth were thermocycled 300X between 5 and 55 degrees C and then stained with silver. Two specimens per tooth were obtained by diamond saw sectioning for measurement of leakage (microm) and microtensile bond strength (MPa) at the gingival wall and then tested for association with regression analysis. Scanning electron microscopy techniques and energy dispersive spectroscopy (EDS) were used to evaluate the debond and leakage pathways. RESULTS Association between leakage and bond strength was not significant (t=1.31, p=0.198). All 74 samples debonded within the joint, predominantly at the hybrid layer-adhesive resin region with only one specimen including a small portion of resin cement in the debond pathway. Secondary and backscatter imaging and EDS analysis showed leakage in all samples that involved the hybrid layer. CONCLUSION This study demonstrates a feasible method for evaluating leakage and bond strength at the joint interface within the same specimen.

Ceramic materials for porcelain veneers: Part II. Effect of material, shade, and thickness on translucency

STATEMENT OF PROBLEM Information regarding the differences in translucency among new ceramic systems is lacking. PURPOSE The purpose of this study was to compare the relative translucency of the different types of ceramic systems indicated for porcelain veneers and to evaluate the effect of shade and thickness on translucency. MATERIAL AND METHODS Disk specimens 13 mm in diameter and 0.7-mm thick were fabricated for the following 9 materials (n=5): VITA VM9, IPS Empress Esthetic, VITA PM9, Vitablocks Mark II, Kavo Everest G-Blank, IPS Empress CAD, IPS e.max CAD, IPS e.maxPress, and Lava Zirconia. VITA VM9 served as the positive control and Lava as the negative control. The disks were fabricated with the shade that corresponds to A1. For IPS e.maxPress, additional disks were made with different shades (BL2, BL4, A1, B1, O1, O2, V1, V2, V3), thickness (0.3 mm), and translucencies (high translucency, low translucency). Color coordinates (CIE L∗ a∗ b∗) were measured with a tristimulus colorimeter. The translucency parameter was calculated from the color difference of the material on a black versus a white background. One-way ANOVA, the post hoc Tukey honestly significant difference, and the Ryan-Einot-Gabriel-Welsch multiple range tests were used to analyze the data (α=.05). RESULTS Statistically significant differences in the translucency parameter were found among porcelains (P<.001) according to the following rank: VM9>PM9, Empress Esthetic>Empress CAD>Mark II, Everest, e.max CAD>e.max Press>Lava. Significant differences also were noted when different shades and thickness were compared (P<.001). CONCLUSIONS Different ceramic systems designed for porcelain veneers present varying degrees of translucency. The thickness and shade of lithium disilicate ceramic affect its translucency. Shade affects translucency parameter less than thickness.

Ceramic materials for porcelain veneers. Part I: Correlation between translucency parameters and contrast ratio.

STATEMENT OF PROBLEM Different parameters are used in the literature to describe translucency, making it difficult for clinicians to find clear information on ceramic translucency and compare studies. PURPOSE The purpose of this study was to assess the correlation between the contrast ratio (CR) and translucency parameter (TP) when the translucency of different types of ceramic systems is compared. MATERIAL AND METHODS Disks 13 mm in diameter and 0.7 mm thick were fabricated for the following materials (n=5): VITA VM9, VITA PM9, IPS Empress CAD, IPS e.max CAD, IPS e.maxPress, and Lava Zirconia. VITA VM9 served as positive control, while Lava Zirconia served as negative control. The luminous reflectance (Y) and color coordinates (CIE L* a* b*) of the specimens were measured with a tristimulus colorimeter. The CR (CR=Yb/Yw) was calculated from the reflectance of the light of the material on a black backing (Yb) to the reflectance on a white backing (Yw). The TP (TP=[(Lb*Lw*)(2+)(ab*-aw*)(2+)(bb*-bw*)(2) ](1/2)) was calculated from the color difference of the material on a black versus a white background. One-way ANOVA based on ranked data and the Pearson and Spearman rank correlation tests were used to analyze the data (α=.05). RESULTS A significant correlation between CR and TP was found when all specimens were included (P<.001). The coefficient of -0.99 indicated a strong decreasing relationship between the 2 variables. CONCLUSIONS Either CR or TP can be used to evaluate the relative translucency of ceramic systems.

Current Strategies in Dentin Remineralization

Partial caries removal procedures are used clinically in an attempt to conserve tooth structure and prevent pulp damage. Within this approach, the caries-infected dentin is removed, and the partially demineralized caries-affected dentin is preserved and sealed with materials that enhance remineralization. Fluoride-releasing glass ionomers have been commonly used for this purpose. Recent studies have shown potential for other cements and bioactive adhesive materials to promote dentin repair through various strategies. These strategies include ion releasing of Ca-P and the guided tissue remineralization or biomimetic remineralization of dentin. The latter is potentially useful in the remineralization of the demineralized acid-etched dentin that is incompletely infiltrated by adhesives in dentin bonding. The purpose of this Critical Appraisal is to provide the clinician with a summary of current literature that clarifies understanding of the process of dentin remineralization and to describe current strategies in this area.

Effect of polishing direction on the marginal adaptation of composite resin restorations.

PROBLEM Polishing composite resin restorations may lead to marginal defects and gap formation. PURPOSE To assess the effect of polishing direction on the marginal adaptation of composite resin restorations using two composite resins and two polishing systems. MATERIALS AND METHODS Forty extracted human molars were sectioned along their mesio-distal axis. Buccal and lingual enamel was flattened and a triangular preparation, 0.87-mm deep and 3-mm wide, representing two 60° bevels, was performed. Specimens were randomly assigned to eight groups (N = 20) and restored with two composite resins: a nanofilled (Filtek Supreme Ultra, 3M ESPE, St. Paul, MN, USA) or a microhybrid (Point 4, Kerr, Orange, CA, USA) and finished with two polishing techniques: polishing discs (Sof-Lex XT, 3M ESPE) or rubber polishers (HiLuster Plus, Kerr, Bioggio, Switzerland). On each specimen, both margins were polished with the same technique, one margin from composite resin to tooth and the other from tooth to composite resin. Replicas were made for field emission scanning electron microscope observation (200×) and quantitative margin analysis was performed based on four criteria. Data were analyzed with a paired-sample t-test, a two-sample t-test, and one-way analysis of variance or their nonparametric analog. RESULTS Significant differences were found in most groups between polishing directions with better marginal adaptation from composite resin to tooth than from tooth to composite resin. Differences between composite resins and polishing techniques seemed to be dependent on certain combinations of composite resin, polishing technique, and polishing direction. CONCLUSION Polishing from composite resin to tooth leads to better marginal adaptation than polishing from tooth to composite resin. CLINICAL SIGNIFICANCE The results obtained from this in vitro study suggest that polishing direction influences the marginal adaptation of composite resins and that polishing from composite resin to tooth structure should be clinically performed whenever possible on accessible margins to preserve marginal integrity and esthetics.

Factors Associated with Reevaluation of the Stepwise Excavation Procedure: An 8-Year Retrospective Study.

Although the stepwise excavation procedure (SWP) has been shown to be an effective caries treatment technique, studies reporting its application outside of controlled clinical trials are limited. We performed a retrospective study from patient record data to assess the proportion of patients who had an SWP reevaluated within 18 months at The University of Iowa College of Dentistry (UICOD) between 2004 and 2012, and evaluated the association between different variables and this outcome. A total of 1,985 SWPs were performed in 1,326 patients, with 518 patients having had reevaluation within 18 months. Bivariate analysis and logistic regression modeling revealed strong associations between explanatory variables such as provider type, tooth type, patient age, number of recalls and the calendar year in which the SWP was done and reevaluation status. There was also evidence of association with dental insurance status. Other characteristics such as gender, distance traveled to the UICOD, number of surfaces treated and tooth arch did not show any significant association. In general, patients were more likely to have reevaluation when seen by faculty members or residents, the procedure was performed in molars/pre-molars, they were older, they had more recalls and were seen earlier in the study period. These results suggest that decisions to use SWP should consider patient demographics and treatment characteristics such as provider level, tooth type, patient age and number of recalls. The impact of treatment year may reflect program heterogeneity or temporal changes in external societal factors.

Acknowledgement to Reviewers 2015

Kasper Aanaes Shawn Aaron Janice Abbott Frank Accurso Moira Aitken Michael Anstead Robert Aris Deborah Baines Jennifer Bartlett Tara Barto Ivan Bastian Jeffrey Beekman Scott Bell William Bennett Ariel Benson Paul Beringer Ariel Berlinski Jocelyn Bescond Julie Biller Diana Bilton Scott Blackman Hannah Blau Cristina Bombieri Richard Boucher Frederic Bouillaud Stephen Bourke Cynthia Brady Michelle Brotherwood Emanuela Bruscia Mandy Bryon Lucy Burr Chris Burtin Andre Cantin Rafael Canton Giussepe Castaldo Carlo Castellani Daniel Chambers Christine Chan Denmark Canada United Kingdom United States United States United States United States United Kingdom United States United States Australia Netherlands Australia United States Israel United States United States France United States United Kingdom United States Israel Italy United States France United Kingdom United States Canada United States United Kingdom Australia Belgium Canada Spain Italy Italy Australia United States Anne Chang Marc Chanson W Winn Chatham Jocelyn Choo Sanjay Chotirmall Oana Ciofu Natalia Cirilli John Clancy Lane Clarke Rubin Cohen Gary Connett Janet Crane Patrick Daigneault Jeannette Dankert-Roelse Elliott Dasenbrook Kausik Datta Peter Davies Gwyneth Davies Frans De Baets RC De Lisle Agnes Delaunay-Moisan Elisabeth Dellon Rajendar Deora Nico Derichs Gill Diamond Antonio DiGiandomenico G. Dimitriou Anh-Tuan Dinh-Xuan John Dodge Scott Donaldson Alistair Duff Helen Egan Olaf Eickmeier Joseph Elborn Marielle Engelen Tom Evans Pascale Fanen Albert Faro Australia Switzerland United states Australia Singapore Denmark Italy United States United States United States United Kingdom United States Canada Netherlands United States United States Australia United Kingdom Belgium United States France United States United States Germany United States United States Greece France United Kingdom United States United Kingdom United Kingdom Germany United Kingdom United States United Kingdom France United States