Effect of finishing instrumentation on the marginal integrity of resin-based composite restorations.

PURPOSE: This study evaluated the effect of the use of different finishing instruments on the marginal integrity of resin composite restorations. MATERIALS AND METHODS: Bovine incisors (N = 75) embedded in epoxy resin had the facial enamel ground and polished to 1200-grit. A standardized cavity (3 x 3 mm, 2 mm deep) was prepared on each specimen and restored with a 2-step total-etch adhesive (Single Bond, 3M ESPE, St. Paul, MN, USA) and a hybrid resin composite (Filtek Z250, 3M ESPE) in a single increment. The restorations were mechanically polished to 1200-grit. Specimens were randomized into different groups (N = 5) according to finishing technique: positive control (1200-grit paper), negative control (regular-grit diamond), fine cross-cut laminated burs, straight-cut laminated burs, spiral-cut laminated burs, and finishing diamonds. The straight-cut burs, spiral-cut burs, and finishing diamonds were tested individually as fine, extra-fine, and ultra-fine, as well as sequentially as a series. A high-speed, water-cooled handpiece under standardized pressure (0.5 N) and time (40 seconds) was used for all finishing procedures. Specimens were processed for scanning electron microscope, and margin gaps were systematically measured. Data were analyzed with one-way analysis of variance and Duncan test. RESULTS: The negative control specimens (course diamond) presented the largest gaps, whereas the positive control specimens (mechanically polished) generated the smallest gaps. No statistically significant difference was noted between the finishing diamonds and the positive control. The negative control exhibited significantly larger gaps when compared with the other finishing instruments. Intermediate results were observed for cross-cut, straight-cut, and spiral-cut laminated burs. Fine, extra-fine and ultra-fine finishing diamonds generated smaller gaps compared with laminated burs, but the differences were not always statistically significant. CONCLUSION: Fine, extra-fine and ultra-fine finishing diamonds used to finish composite restorations generated better marginal integrity when compared with carbides and regular-grit diamonds. CLINICAL SIGNIFICANCE When finishing composite restorations, finishing diamond burs result in better composite margins than carbide laminated burs.

Kidney transplantation from anti-HBc+ donors: results from a retrospective Italian study.

BACKGROUND: The risk of transmitting a hepatitis B virus (HBV) infection from donor kidneys with a past HBV serological profile may be negligible. Data on HBV transmission to kidney transplant recipients from donor organs that were anti-HBc/HBsAg in Italy has not been previously reported. Anti-HBc testing in cadaver organ donors has been mandatory in Italy since 2002, when anti-HBc determinations were included in the National Guidelines for donor evaluation. Therefore, prior to that date kidney recipients from anti-HBc/HBsAg donors can be identified retrospectively where stored serum is available for testing. METHODS: The prevalence of anti-HBc Italian organ donors, the incidence of HBV transmission according to the recipients' HBV status (vaccinated, recovered, or naive), and the clinical impact (5-year graft and patient survival rates) in the North Italy Transplant program was evaluated by retrospectively screening for anti-HBc antibodies in the sera of cadaver kidney donors used in transplants from 1997 to 1999. RESULTS: Two hundred and ten donors were found to have been anti-HBc. At the time of the study, no active infection was observed in any of the 344 HBsAg recipients, but 4/140 (2.86%) of the vaccinated recipients were found to have been anti-HBc/HBsAg. None of these patients, however, had any biochemical or clinical history of HBV infection. Patient and graft survival rates of anti-HBc or anti-HBc kidney recipients did not differ statistically. CONCLUSION: Kidney grafts from anti-HBc donors should be considered in all recipients because the benefit obtained from the transplantation out weighs the negligible risk of HBV transmission.

Epidemiologic study on the origin of cancer after kidney transplantation.

BACKGROUND: Subjects who underwent solid organ transplantation are at higher risk for a wide variety of cancers. METHODS: The authors investigated the origin of cancer in a cohort of 2,526 patients followed up for 60.7 +/- 35.6 months after kidney transplantation between 1990 and 2000 in seven transplant centers. RESULTS: One hundred four of them developed cancer. All subjects who developed solid cancer within 6 months after transplantation (n=10) and a group of subjects who developed solid cancer after 6 months posttransplant (n=10) were selected. Short tandem repeat analysis was performed on paraffin-embedded biopsy specimens of tumors and on both donor and recipient pretransplant peripheral blood. Biologic material was obtained in 17 of the 20 selected patients (85.0%). The analysis showed that 16 of 17 tumors were genetically identical to the recipient. CONCLUSIONS: The authors' results suggest that donor transmission of solid cancer is an unlikely event in their population.

Utilization of blended learning to teach preclinical endodontics.

Blended learning (BL) is the integration of classroom learning with an online environment. The purpose of this study was to determine whether dental students who experienced BL in a preclinical endodontic course demonstrated better manual skills, conceptual knowledge, and learning experience compared to those experiencing traditional learning. All eighty-one students (100 percent) in a preclinical endodontics course agreed to participate and were assigned to either the traditional or BL group. A root canal procedure was used to determine the level of manual skills gained by each group. Pre- and post-intervention quizzes were given to all students to evaluate conceptual knowledge gained, and the students' perspectives on the methods were evaluated with a survey. The BL group scored better than the traditional group on the manual skills exercise at a statistically significant level (p=0.0067). There were no differences in the post-intervention quiz scores between the two groups, and the students' opinions were positive regarding BL. With BL, the students were able to learn and demonstrate dental skills at a high level.

Renal transplantation. Strategies to prevent organ rejection--the role of an inter-regional reference center.

This paper summarizes the role of the Inter-Regional Reference Center (RC) of the North Italy Transplant program (NITp), in coordinating a donor procurement and organ transplantation network, with a special focus on the strategies to minimize immunological risk and complications after transplantation. In the NITp, patients enrolled on the renal transplantation (RT) waiting list are typed for HLA-A,B,DRB1 antigens with a genomic method. They are periodically screened for the presence of lymphocytotoxic antibodies in their serum by the RC and their suitability to receive the transplant is checked periodically. Cadaver kidney allocation is ruled by a computerized algorithm, named NITK3, established in 1997, which aims at ensuring quality, equity, transparency and traceability during all the phases of the allocation decision-making process. NITK3 has been set up by the NITp Working Group on the basis of biological, medical and administrative criteria and it is periodically reviewed after the analysis of transplant results. In this paper, we show the results of a preliminary analysis of RTs performed from 1998 to 2002 in nine out of sixteen centers of the NITp area, which demonstrates the general quality of the NITp program in terms of patients and graft survival and the special attention to the patients at higher immunological risk.