Monomer conversion in dual-cured core buildup materials

Objectives: To examine the impact of self-curing (SC) and light-curing (LC) mechanisms on the curing efficiency of dual-cured buildup restorative materials (DCB). Methods: The DCB materials tested were: Clearfil DC Core Automix (CD), Cosmecore DC (CM), LuxaCore DC (LX) and MultiCore DC Flow (MC). The SC material Clearfil Core New Bond (CN) and the LC material Clearfil Photo Core (CP) were used as controls. Specimens (0=4 mm, d=1 nun, n=4) of DCB materials prepared without light-exposure were tested after 10-, 20-, 30- and 60-minutes of storage in dark and dry conditions (37°C), whereas DCB specimens light-cured immediately after mixing (20 seconds, 850mW/cm2) served as a reference. The amount of remaining C=C bonds (%RDB) was measured on the bottom specimen surfaces using ATR-FTIR spectroscopy. One-way ANOVA and multiple comparison tests were used to evaluate the statistically significant differences (a=0.05). Results: Polymerization mode had a strong effect on the polymerization efficacy of the DCB materials (p<0.0001). The control materials (CN, CP) performed better than the DCB materials (p<0.0001), except for LX in the LC mode. LX and MC showed better SC conversion during the initial 20-minute period. After 60 minutes, the %RDB values of CM were still above 60%, whereas in CD and LX, they reached the level of LC specimens. Conclusions: The LC initiation mechanism of the DCB materials that were tested resulted in better C=C conversion when compared to their native SC mechanisms. The SC and LC control materials performed better than the DCB materials, with the exception of LX in the LC mode

A comparative evaluation of two working length determination methods

The purpose of this study was to explore the level of agreement between the radiographic and the electronic apex locator (EAL) working length assessment methods, amongst teeth with different diagnoses. Working length measurements along with pulpal and periapical diagnoses data were collected from the Patient Registry Database of our Institution. The null hypothesis of this study was that pulp status does not affect the level of agreement between the two methods. The degree of agreement was assessed using the Bland–Altman method, followed by a Kruskal–Wallis test (a = 5%) that would allow the null hypothesis to be accepted. The EAL measurements agree in general with those provided by a 1.5 mm file placed coronal to the radiographic apex amid teeth with different pulpal diagnoses. Within the limitations of this study, we suggest that this setting (i.e. the distance) may be applied to all cases of endodontically treated teeth, despite the differences in pulpal diagnosis. © 2018 Australian Society of Endodontology In

Different patterns of restoration provision between initial endodontic treatment and retreatment: A retrospective clinical study

Purpose: The aim of this study was to investigate the relationship between type of endodontic treatment and choice of definitive restoration and to show the prevalence of endodontic treatment options according to patient age and type of tooth. Materials and Methods: Data were collected from the archive system of the School of Dentistry, National and Kapodistrian University of Athens in Athens, Greece. The sample included endodontically treated teeth being restored definitively at the time of data collection. Results: Statistically significant difference was found regarding the type of restoration between initial endodontic treatments and retreatments (P < .001). Conclusion: Endodontic retreatment seemed to have a significant effect on the choice of definitive restoration of the tooth. © 2017 by Quintessence Publishing Co Inc

Comparative evaluation of topographical data of dental implant surfaces applying optical interferometry and scanning electron microscopy

Objective Comparability of topographical data of implant surfaces in literature is low and their clinical relevance often equivocal. The aim of this study was to investigate the ability of scanning electron microscopy and optical interferometry to assess statistically similar 3-dimensional roughness parameter results and to evaluate these data based on predefined criteria regarded relevant for a favorable biological response. Methods Four different commercial dental screw-type implants (NanoTite Certain Prevail, TiUnite Brånemark Mk III, XiVE S Plus and SLA Standard Plus) were analyzed by stereo scanning electron microscopy and white light interferometry. Surface height, spatial and hybrid roughness parameters (Sa, Sz, Ssk, Sku, Sal, Str, Sdr) were assessed from raw and filtered data (Gaussian 50 μm and 5 μm cut-off-filters), respectively. Data were statistically compared by one-way ANOVA and Tukey–Kramer post-hoc test. For a clinically relevant interpretation, a categorizing evaluation approach was used based on predefined threshold criteria for each roughness parameter. Results The two methods exhibited predominantly statistical differences. Dependent on roughness parameters and filter settings, both methods showed variations in rankings of the implant surfaces and differed in their ability to discriminate the different topographies. Overall, the analyses revealed scale-dependent roughness data. Compared to the pure statistical approach, the categorizing evaluation resulted in much more similarities between the two methods. Significance This study suggests to reconsider current approaches for the topographical evaluation of implant surfaces and to further seek after proper experimental settings. Furthermore, the specific role of different roughness parameters for the bioresponse has to be studied in detail in order to better define clinically relevant, scale-dependent and parameter-specific thresholds and ranges. © 2017 The Academy of Dental Material