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Item Longevity of Crown Margin Repairs Using Glass Ionomer: A Retrospective Study(2020) Watson, Justin I.; Cook, N. Blaine; Thyvalikakath, Thankam; Diefenderfer, Kim E.; Capin, OrianaObjectives: Repair of crown margins may extend the functional life of existing crowns. However, the longevity of such treatment is unknown. This study determined the survival time of crown margin repairs (CMR) with glass-ionomer (GI) and resin-modified glass-ionomer cements. Methods: We queried axiUm (Exan Group, Coquitlam, BC, Canada) database for permanent teeth that underwent CMR in the Graduate Operative Dentistry Clinic, Indiana University School of Dentistry (IUSD), Indianapolis, Ind., USA, from January 1, 2006 through January 1, 2018. Since there is no CDT code for the CMR procedure, CDT codes for resin-composite and GI restorations (D23XX) were queried; these patients also had treatment notes that indicated CMR. The final data set included patient ID, birth date, gender, dates of treatments, CDT codes, tooth type, tooth surface and existing findings. Two examiners developed guidelines for record review and manually reviewed the clinical notes of patient records to confirm CMR. Only records that were confirmed with the presence of CMR were retained in the final dataset for survival analysis. Survival time was calculated by Kaplan-Meier statistics and a Cox Proportional Hazards model was performed to assess the influence of selected variables (p < 0.05). Results: 214 teeth (115 patients) with CMR were evaluated. Patient average age was 69.4 11.7 years old. Posterior teeth accounted for 78.5 percent (n = 168) of teeth treated. CMRs using GI had a projected 5-year survival rate of 62.9 percent (K-M Analysis) and an 8.9 percent annual failure rate. Cox Proportional Hazards Regression analysis revealed that none of the factors examined (age, gender, tooth type) affected time to failure. Conclusion: CMRs may extend the longevity of crowns with defective margins. Larger EHR studies or case control studies are needed to investigate other variables, such as the caries risk status or the severity of defects that may affect the survival rate of CMRs.Item Microtensile bond strength of new paste/paste resin-modified glass ionomer cement systems : the effect of dentin pretreatment(2011) Al-Fawaz, Yasser Fawaz, 1983-; Cook, Norman Blaine, 1954-; Hara, Anderson T.; Matis, Bruce A.; Cochran, Michael A. (Michael Alan), 1944-; Bottino, Marco C.MICROTENSILE BOND STRENGTH OF NEW PASTE/PASTE RESIN-MODIFIED GLASS IONOMER CEMENT SYSTEMS: THE EFFECT OF DENTIN PRETREATMENT by Yasser Fawaz Al-fawaz Indiana University School of Dentistry Indianapolis, Indiana Background: In order to improve the clinical performance of RMGIC 3M ESPE and GC America introduced paste/paste resin-modified glass ionomer cements, Ketac™ Nano and Fuji Filling™ LC, respectively. Both companies developed non-rinse substrate conditioners (i.e., Ketac Nano Primer-3M ESPE and GC Self-Conditioner-GC America) that should be used with these new materials instead of the conventional polyacrylic acid. It has been also advised by both manufacturer’s to use this novel substrate conditioner with the previously marketed RMGICs. Objective: to investigate whether the use of novel non-rinse conditioners (i.e., Ketac Nano Primer 3M ESPE and GC Self Conditioner GC America) as substrate pre-treatment and the new paste/paste resin-modified glass-ionomer cement, RMGIC (Ketac™ Nano 3M ESPE and Fuji Filling™ LC GC America) would affect the microtensile dentin bond strength (µTBS) of the material when compared to the traditional RMGIC with polyacrylic acid as a surface substrate pre-treatment. Materials and Methods: 96 extracted non-restored human molar were sectioned to expose occlusal dentin. Dentin surface was finished with SiC paper to standardize the smear layer. Bonding protocols of the different materials to dentin were performed following the use of two dentin conditioners. Eight groups (n=12) were tested: G1: Ketac Nano Primer + Ketac Nano, G2: Ketac Conditioner + Ketac Nano, G3: Ketac Nano Primer + Photac Fil, G4: Ketac Conditioner + Photac Fil, G5: GC Self Conditioner + Fuji Filling LC, G6: GC Cavity Conditioner + Fuji Filling LC, G7: GC Self Conditioner + Fuji II LC and G8: GC Cavity Conditioner + Fuji II LC. The specimens were stored in 37°C for 24h in 100% humidity before cutting non-trimmed beams for the µTBS with cross-sectional areas of approximately 0.8 × 0.8 mm2. Nine beams were used from each specimen. Test was done using universal testing machine at a cross-head speed of 1mm/min. Debonded specimens were examined under a stereomicroscope at 45× magnification to evaluate the failure mode. Eight randomly chosen representative debonded beams were imaged under a scanning electron microscope (SEM). Results: µTBS in MPa (mean ± SE) were: G1: 9.5±1.0, G2: 11.0±1.0, G3:20.0±1.0, G4:16.8±0.9, G5: 15.1±1.0, G6: pre-test failure, G7: 20.0±1.0, G8:14.1±0.9. Weibull-distribution survival analysis was used to compare the differences in microtensile peak stress among the groups. Group5 has cohesive predominant faultier mod while the other groups have adhesive predominant failure. Conclusion: Within the limitations of this study, the use of the novel non-rinse conditioners did not improve the microtensile bond strength of new paste/paste RMGIC to dentin. In fact, the use of the novel non-rinse conditioners enhanced the bond strength of the traditional RMGIC to dentin.