RESUMEN
The aim of this study is to investigate the combined effect of a digital manufacturing technique (subtractive vs. additive), preparation taper (10° vs. 20° TOC), and finish line (chamfer vs. shoulder) on the marginal adaptation of temporary crowns following cementation with a compatible temporary cement. Four mandibular first molar typodont teeth were prepared for full coverage crowns with standard 4 mm preparation height as follows: 10° TOC with the chamfer finish line, 10° TOC with the shoulder finish line, 20° TOC with the chamfer finish line and 20° TOC with the shoulder finish line. Each of the four preparation designs were subdivided into two subgroups to receive CAD/CAM milled and 3D-printed crowns (n = 10). A total of 80 temporary crowns (40 CAD/CAM milled and 40 3D-printed) were cemented to their respective die using clear temporary recement in the standard cementation technique. The samples were examined under a stereomicroscope at ×100 magnification following calibration. Linear measurements were performed at seven equidistant points on each axial surface and five equidistant points on each proximal surface. One-way ANOVA analysis and Tukey HSD (Honestly Significance Difference) were performed. The best marginal fit was seen in group 8, while the poorest fit was noted in group 2. Shoulder finish lines and 10° TOC resulted in higher marginal gaps, especially in CAD/CAM milled group. The selection of 3D-printed crowns may provide a better marginal fit within the range of clinical acceptability. Marginal gaps were within clinical acceptability (50 and 120 µm) in all groups except group 2.
RESUMEN
BACKGROUND: The risk of tuberculosis is increased in solid organ transplantation. Rates remain high in developed and developing countries. We developed protocols to better identify transplant recipients at risk of tuberculosis and initiate interventions to prevent tuberculosis. OBJECTIVES: Report tuberculosis incidence in solid-organ transplant recipients and the results of expanded isoniazid prophylaxis in deceased-donor renal transplantation. DESIGN: Retrospective cohort study, comparing two time periods. SETTING: Large transplantation center in a WHO-medium endemicity country for tuberculosis. METHODS: In a cohort of all solid-organ transplant recipients performed between 2003 and 2012, tuberculosis-free transplantation follow-up is used for incidence calculation. Rates of tuberculosis in renal transplant recipients are compared before and after implementation of expanded isoniazid prophylaxis. MAIN OUTCOME MEASURE(S): Active tuberculosis post-transplantation. RESULTS: Of 1966 solid-organ transplant recipients (kidney: 1391, liver: 426, heart: 114, lung: 35), 20 recipients (1.02%) developed tuberculosis. Twelve cases (60%) developed tuberculosis within one year of transplantation. The incidence was 248 cases per 100 000 transplant-years. The proportion of transplant recipients (incidence of tuberculosis per 100 000 transplant-years) for specific organs were kidney 0.58% (127), liver 1.88% (594), heart: 1.75% (570), and lung 5.71% (4750). In the survival analysis, lung transplant recipients had significantly higher rates of tuberculosis compared to recipients of kidneys from living donors (P=.0001) with a rate ratio of 45.3 (95% CI: 7-313). Mortality was 5% among tuberculosis patients. After implementing expanded isoniazid prophylaxis among deceased-donor kidney recipients, no tuberculosis occurred in 177 recipients, compared to 3 out of 155 (2%) recipients before implementation. CONCLUSIONS: Rates of tuberculosis among our solid transplant recipients are decreasing. Universal iso-niazid prophylaxis in transplant recipients could reduce transplant-associated tuberculosis in endemic areas. LIMITATIONS: Donor data on tuberculosis exposure and prevention and tuberculosis prevention efforts before referral to our center are not available for all patients.