Browsing by Author "Brown, David"
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Item Association between clinician team segregation, receipt of cardiovascular care and outcomes in valvular heart diseases(Wiley, 2025) Bolakale-Rufai, Ikeoluwapo Kendra; Knapp, Shannon M.; Bisono, Janina Quintero; Johnson, Adedoyin; Moore, Wanda; Yankah, Ekow; Yee, Ryan; Trabue, Dalancee; Nallamothu, Brahmajee; Hollingsworth, John M.; Watty, Stephen; Williamson, Francesca; Pool, Natalie; Hebdon, Megan; Ezema, Nneamaka; Capers, Quinn; Blount, Courtland; Kimbrough, Nia; Johnson, Denee; Evans, Jalynn; Foree, Brandi; Holman, Anastacia; Lightbourne, Karen; Brown, David; Tucker Edmonds, Brownsyne; Breathett, Khadijah; Medicine, School of MedicineAims: Racial disparities exist in clinical outcomes for valvular heart disease (VHD). It is unknown whether clinician segregation contributes to these disparities. Among an adequately insured population, we evaluated the relationship between clinician segregation in a hospital and receipt of care by a cardiologist according to patient race. We also evaluated the association between clinician segregation, race and care by a cardiologist on 30-day readmission and 1-year survival. Methods and results: Using Optum's Clinformatics® Data Mart Database (CDM, US commercial and Medicare beneficiaries) from 2010 to 2018, we identified patients with a primary diagnosis of VHD. Hospitals were categorized into low, medium and high segregation groups (SG), according to clinician segregation index (SI). SI can range from 0-1 (0: the ratio of Black to White patients is the same for all clinicians; 1: each clinician treats only Black or only White patients). Outcomes were analysed using generalized linear mixed effect models. Among 8649 patients [median age 75 (67-82), 45.4% female, 16.1% Black, 83.9% White], odds of care from a cardiologist did not vary across race for all SGs [Low SG adjusted odds ratio (aOR): 0.79 (95% CI: 0.58-1.08), P = 0.14; Medium SG aOR: 0.86 (95% CI: 0.60-1.25), P = 0.43; High SG aOR: 1.07 (95% CI: 0.68-1.69), P = 0.76]. Among those that received care from a cardiologist, there was no difference in the 30-day readmission between Black and White patients across SGs [Low SG aOR: 1.05 (95% CI: 0.83-1.31), P = 0.70; Medium SG aOR: 1.22 (95% CI: 0.92-1.61), P = 0.17; High SG aOR: 0.81 (95% CI: 0.57-1.17), P = 0.27]. Among patients that did not receive care from a cardiologist, Black patients in low SG had higher odds of 30-day readmission compared to White patients [aOR: 2.74 (95%CI:1.38-5.43), P < 0.01]. Odds of 1-year survival were similar across race for all SG irrespective of receipt of care from a cardiologist [seen by a cardiologist: Low SG aOR: 1.13 (95% CI: 0.86-1.48), P = 0.38; Medium SG aOR: 0.83 (95% CI: 0.59-1.17), P = 0.29; High SG aOR: 1.01 (95% CI: 0.66-1.52), P = 0.98; not seen by a cardiologist: Low SG aOR: 0.56 (95% CI: 0.23-1.34), P = 0.19; Medium SG aOR: 0.81 (95% CI: 0.28-2.37), P = 0.70; High SG aOR: 0.63 (95% CI: 0.23-1.74), P = 0.37]. Conclusions: Among an insured population, race was not associated with care by a cardiologist for VHD or survival. Black patients not seen by cardiologists had higher odds of 30-day readmission in low clinician SG.Item The effect of a novel photoinitiator system (RAP) on dental resin composites' flexural strength, polymerization stress, and degree of conversion(2009) Schaub, Kellie; Platt, Jeffrey A., 1958-; Andres, Carl J., 1942-; Levon, John A.; Brown, David; Hovijitra, Suteena, 1944-Objectives: A new technology has been introduced into the field of dental resin composites that professes to enhance light-curing efficiency. Rapid amplified photopolymerization (RAP) initiator technology has not yet been fully compared with resin composites with conventional initiators such as camphorquinone (CQ). The purpose of this study was to compare and contrast the effects of this novel technology (RAP) on properties of two light-cured resin composites. Flowable (EFQ) and microfilled (ESQ) experimental composites were fabricated and supplied from Tokuyama Dental with (w/RAP) and without RAP (w/o RAP). The flexural strength (MPa) and flexural modulus (MPa) were obtained using a three-point bending apparatus (Sintech Renew 1123, Instron Engineering Corp., Canton, MA). Polymerization stress curves were created using a tensometer (American Dental Association Health Foundation, NIST, Gaithersburg, MD) which were then used to calculate the maximum stress rate. Finally, the degree of conversion was measured using infrared spectroscopy (Jassco FT-IR spectrometer, Model: 4100, Jasco Corporation, Tokyo, Japan). When evaluating the flexural strength, the peak stress for EFQ w/RAP was significantly higher than EFQ w/o RAP (p = 0.0001). This was statistically not significant for the ESQ group, even though ESQ w/RAP did have a higher peak stress then ESQ w/o RAP (p = 0.28). The interaction between resin type and RAP was not significant when evaluating the flexural modulus (p = 0.21). Formulations with RAP had a significantly higher flexural modulus then w/o RAP (p = 0.0001). Experimental resins with RAP had significantly higher maximum stress rates than those w/o RAP when evaluating polymerization stress (p = 0.0001). Finally, groups w/ RAP appeared to have a higher degree of conversion than groups without (p = 0.0057). This study showed that the experimental composites with RAP had greater mechanical properties than those without. Unfortunately, the increase in polymerization stress causes concern clinically due to the chance of leakage at the restoration/tooth interface. One of the main potential disadvantages of this new RAP technology is an increase in the polymerization stress. Deciding if this amount of polymerization stress is clinically acceptable is yet to be accomplished.Item The effect of using variable curing light types and intensities on the parameters of a mathematical model that predicts the depth of cure of light- activated dental composites(2009) Ridha, Hashem; Levon, John A.; Andres, Carl J.; Chu, Tien-Min Gabriel; Brown, David; Hovijitra, SuteeraThe purpose of this study is to further investigate the effect of using six different light source types with different light output intensities on the parameters of a mathematical model that predicts the DOC in VLDC’s. In this equation: D = Dp In(E0/Ec), D is the depth of cure in millimeters, E is the curing energy in J/cm2, Ec is the critical curing energy for the composite to reach a gel layer, and Dp is a characteristic coefficient. Three LED and three halogen dental curing units with different light output intensities were used to cure three shades (B1, A3, D3) of a hybrid resin composite. The exposure duration was at the intervals of 10, 20, 30, and 40 seconds for each sample setting. ISO scraping technique was performed to measure the depth of cure of each sample. Regression analysis was used to assess the fit of the proposed mathematical model D = Dp In(E0/Ec) to the experimental data obtained in this study. 72 For all the shade-light combinations; A3, B1, and D3 had significantly different regression lines (P < 0.05) with significantly higher Dp and Ec for B1 than A3 and D3. The only exceptions were for the Ec values between B1 and D3 in Allegro, Astralis 5, and Visilux 2 groups; and the Ec between A3 and B1 in Allegro group. The Dp and Ec parameters didn’t show significant differences between A3 and D3 shades in all the groups. Also, most of the significant differences for Dp values occurred in the B1 shade-light combinations; however, none of the D3 shade-light combinations showed significant differences for Dp. Several factors play combined influential effects on the kinetics of polymerization and depth of cure in VLDC’s. The shade has a more dominant effect on both parameters Dp and Ec than the curing light type or source output intensity. As we cure lighter shades “B1,” the effect of using different lights with different output intensities on the two parameters Dp and Ec will be greater and more significant than for darker shades “A3 or D3.” The clinical significance drawn from this study is that clinicians should recognize that using curing lights w/ increased output intensities doesn’t absolutely increase the DOC of VLDC’s especially with the darker shades.Item Flexural strength comparison of monolayer resin composite to bilayer resin/ liner composite(2009) Azzam, Mai; Platt, Jeffrey A.; Levon, John; Taskonak, Burak; Brown, David; Andres, Carl; Legan, JosephClinical evidence suggests that the use of liners in posterior composite restorations may increase the frequency of restoration fractures. Materials that have been used as liner materials for resin composite (RC) restoration include conventional glass ionomers, resin-modified glass ionomers (RMGI), and flowable composites. The aim of this study was to compare the flexural strength of a monolayer of resin composite with that of a bilayer of resin composite and liner. Four types of RC beams were tested: a monolayer control that is an un-lined RC (Tetric EvoCeram, Ivoclar Vivadent) and three “bilayer” specimens that consisted of this same RC lined with one of three liners. The three liners used included two RMGI cements (Vitrebond LC liner; 3M ESPE and, GC Fuji Lining LC; GC America) and a flowable resin composite (Tetric EvoFlow, Ivoclar Vivadent). Each group was tested after water storage for 24 h and 30 d. Altogether, eight, 12-specimen groups were fabricated and tested. Methods: A 25 x 2 x 2 mm mold was completely filled with the RC to form the control beams. To form the bilayer beams, this mold was filled with 0.5 mm of the liner and then with 1.5 mm of the RC. Specimens were stored in 37oC distilled for either 24 h or 30 d. Immediately prior to testing, the 30-day groups were also thermocycled 2500 times, between water baths at 7 oC and 48oC with a 30-s dwell time and a 10-s transit time. Flexural strength was determined using a three-point–bending device. A twoway analysis of variance (ANOVA) with interactions was used to investigate how liner group (or no liner) and storage time affected strength. Results: The interaction between liner type and storage time was significant (p = 0.0128). The un-lined RC (the monolayer beam) was significantly stronger after 24 h than after 30 d in water (p = 0.0098). Water storage between 24 h and 30 d did not change the flexural strength of any of the bilayer (lined) beams (p > 0.05). After storage for 24 h and also for storage for 30 d, both un-lined RC and RC lined with the flowable RC exhibited significantly higher flexural strength (p = 0.0001) than the bilayer beams lined with either RMGI liners.Item Influence of coloring techniques and cement opacity on the optical properties of high translucent monolithic zirconia(2017) Yang, Chao-Chieh; Phasuk, Kamolphob; Chu, Tien-Min Gabriel; Brown, David; Levon, John A.Background: With the improvement of CAD/CAM technology and translucency of zirconia material, the full contour zirconia crown was introduced to offer dentists a metal free, high strength, and acceptable esthetic prosthesis option. In addition, it is claimed that it is possible to make a full contour high translucent zirconia crown close to natural tooth color by using coloring liquid. However, there is little information in the literature regarding the effect of coloring techniques and cement color on the optical properties of high translucent zirconia. Objective :1) To evaluate the effect of the coloring liquid technique on the resulting optical properties of a monolithic high translucent zirconia 2) To evaluate the cumulative effect of the cement color on the resulting optical properties of a monolithic high translucent zirconia. Alternative hypothesis: There is a significant difference in optical properties between the high translucent monolithic zirconia ceramics with different color staining technique. In addition, the use of shaded resin cement has an effect on the final optical properties of high translucent monolithic zirconia ceramics. Materials and methods: 35 specimens of high translucent zirconia (11mm x11mm) with thickness 1mm was divided into 5 groups according coloring technique, as follows: no color, submerge, two layers of painting, four layers of painting, and six layers of painting. All specimens were measured for the Δ E, transparent parameter (TP), and opalescence parameter(OP) by spectrophotometer (CM-2600D) after firing. Forty-two specimens of high translucent zirconia (11mm x11mm) with thickness 1mm were divided into three groups according to cement color, as follows: clear, opaque, and A2. After firing and cementing with ND4 resin Block. The Δ E, TP and OP will be measured by spectrophotometer. Statistics: The data were analyzed with significant level set at 0.05 one way ANOVA followed by pair-wise group comparisons using Fisher’s Protected Least Significant Differences. Result: 1) The shade of cement significantly affected the mean value of ΔE of E-max CAD and BruxZir high translucent zirconia restoration. Using opaque cement combined with E-max CAD resulted in color difference that was above the clinically perceptible level (ΔE> 3.7). 2) With more layers of staining liquid application, the ΔE and value decreased. The six-layered group showed lowest mean delta ΔE value of 22 (0.78). ΔE was significantly different among groups (p<0.0001). The submerged group showed higher ΔE than the all painting groups. Conclusions: Based on the results of the study, the colors of BruxZir high translucent zirconia and E-max CAD restorations were affected by the shade of cement, whereas white opaque resin cement resulted in BruxZir high translucent zirconia more yellowish. The results of the study demonstrated that the staining technique has an influence on value and final color of Lava-Plus high translucent. Therefore, it is recommended to consider staining technique as one of the influential factors on the final color of zirconia crowns.Item Relationship Between Health Care Team Segregation and Receipt of Care by a Cardiologist According to Patient Race in a Midwestern State(American Heart Association, 2025) Quintero Bisonó, Janina; Knapp, Shannon M.; Trabue, Dalancee; Yee, Ryan; Williamson, Francesca; Johnson, Adedoyin; Watty, Stephen; Pool, Natalie; Hebdon, Megan; Moore, Wanda; Yankah, Ekow; Ezema, Nneamaka; Kimbrough, Nia; Lightbourne, Karen; Tucker Edmonds, Brownsyne; Capers, Quinn; Brown, David; Johnson, Denee; Evans, Jalynn; Foree, Brandi; Holman, Anastasia; Blount, Courtland; Nallamothu, Brahmajee; Hollingsworth, John M.; Breathett, Khadijah; Medicine, School of MedicineBackground: Segregation index (SI) has been associated with worsened health. However, the relationship between SI within health care teams (degree of heterogeneity between teams caring for Black compared with White patients) and cardiovascular care is unclear among adequately insured populations. We sought to assess the relationship between health care team SI, patient race, receipt of care by a cardiologist, 1-year survival, and 30-day readmission rates for Black compared with White patients admitted with heart failure, ischemic heart disease, or valvular heart disease. Methods: Using Optum's de-identified Clinformatics Data Mart Database (CDM) from 2009 to 2020, generalized linear mixed-effects were used to analyze effects of patient race and SI on receipt of care by a cardiologist, and care by a cardiologist on 1-year survival and 30-day readmission. Results: Among 6572 patients (17.1% Black), the odds of receiving care by a cardiologist were 31.3% less for Black than White patients (adjusted odds ratio 0.687 [95% CI, 0.545-0.872]; P=0.001). However, there was no statistically significant association of SI on receipt of care by a cardiologist (P=0.14). For those seen by a cardiologist, the adjusted odds ratio (Black-to-White) of 1-year survival increased with increasing SI (P=0.02). SI had no statistically significant effect on 30-day readmission (P=0.86). Conclusions: Among patients hospitalized for heart failure, ischemic heart disease, or valvular heart disease, segregation of health care teams was not associated with receipt of care by cardiologists in Indiana hospitals. When cardiologists were included, the odds of 1-year survival increased for Black versus White patients with increasing segregation of clinicians, and segregation was not associated with 30-day readmission.Item Translucency and degree of conversion of resin cement with different thickness of full contour zirconia(2015) Supornpun, Noppamath; Chu, Tien-Min Gabriel; Brown, David; Hovijitra, Suteera; Bottino, Marco C.; Levon, John A.Background: Traditionally, zirconia has been used as a core material for allceramic crowns that are later covered by a more esthetic veneering layer. Recently, new zirconia materials with higher translucency commonly referred to as the “full contour zirconia” have been introduced with the aim to allow dentist to fabricate entire allceramic crown from the material with acceptable esthetic and mechanical functions without the need for veneering. However, there is little information in the literature regarding the translucency of full contour zirconia and the degree of conversion of resin cement underneath the full contour zirconia. Objectives: 1) To investigate the translucency parameter (TP) of recently marketed full contour zirconia and compare that to traditional zirconia and lithium disilicate glass ceramic (LDGC) at different thicknesses. 2) To evaluate the degree of conversion (DC) of the resin cement through different thicknesses of the full contour zirconia, traditional zirconia and LDGC. Alternative hypothesis: The new generation zirconia at the clinically recommended thickness has lower translucency than that of LDGC and higher than that of non-veneered traditional zirconia. In addition, DC of resin cement under full contour zirconia is lower than that of LDGC and higher than that of traditional zirconia. Methods: 150 ceramic specimens (12 x12 mm with thickness of 1-2 mm for LDGC and Zirconia) were divided into 6 groups according to the type of material, as follow: LDGC (IPS e-max CAD), Traditional Zirconia (CAP QZ), full contour zirconia (CAP FZ, Zirlux, Bruxzir, KDZ Bruxer). The TP for materials at various thicknesses were measured by a spectrophotometer (CM-2600D). The DC of the light curing resin cement (Variolink II) underneath the ceramic disks was measured by FTIR. Result: All full contour zirconia has lower translucency parameter and light transmission than LDGC. The translucency parameter decreases with increasing thickness of any type of ceramic. There were no significant differences in the degree of conversion of resin cement among the type of ceramic disc, except Bruxzir. The correlation of TP between various thicknesses and the types of ceramic materials was established by a regression analysis.