Enabling High-Performance Surfaces of Biodegradable Magnesium Alloys via Femtosecond Laser Shock Peening with Ultralow Pulse Energy.

The fast degradation rate and poor wear resistance of magnesium (Mg) alloys in physiological environments have limited their potential usage as next-generation biodegradable orthopedic implant materials. In this work, femtosecond laser shock peening (fs-LSP) was successfully applied to simultaneously improve the surface mechanical, corrosion, and tribocorrosion properties of WE43 Mg alloys in blood bank buffered saline solution at body temperature. Specifically, the treated surfaces of WE43 Mg alloys via fs-LSP with ultralow pulse energy were investigated under different power densities, confining mediums, and absorbent materials. It was found that the combination of a black tape and a quartz layer gave the optimum peening effect under a power density of 28 GW/cm2, which simultaneously strengthened the surface and reduced the corrosion kinetics. In addition, a rapid self-repassivation was observed in fs-LSP-treated WE43 surfaces during tribocorrosion, promising sustained corrosion resistance under mechanical loading, critical to the reliability of load-bearing implants. Finally, the subsurface microstructural evolution and residual stress development in WE43 after fs-LSP were discussed based on the results from transmission electron microscopy analysis and finite element simulations.

A prospective clinical trial of single Astra Tech 4.0 or 5.0 diameter implants used to support two-unit cantilever bridges: results after 3 years.

OBJECTIVE: To evaluate the use of a single Astra Tech implant to support a two-unit cantilever fixed dental prosthesis. MATERIALS AND METHOD: Twenty-nine subjects with an edentulous space (at least equivalent to two bicuspid units) in the premolar/molar segments of the maxilla or mandible with opposing natural teeth or a fixed/removable prosthesis were treated. They were provided with either a 4 or 5.0 mm diameter fixture MT OsseoSpeed. Prostheses were constructed using a cast-to abutment as a one-piece unit with porcelain fused to precious metal to allow direct screw retention. RESULTS: Subjects expressed a high satisfaction with treatment, including appearance and function. The most important complication was abutment screw loosening. It occurred as a single episode in four subjects and in another six subjects the loosening was recurrent. Bone levels were stable and there were no significant differences in radiographic bone height between cantilever and non-cantilever sides of the implant at any time point. CONCLUSION: Single implants can be successfully used to support two-unit cantilever FDPs in the premolar region. A common factor could not be identified in relation to abutment screw loosening.

Probiotic and prebiotic use in patients with inflammatory bowel disease: a case-control study.

BACKGROUND: The use of complementary and alternative medicine in inflammatory bowel disease (IBD) has been extensively studied. However, the use of probiotics and prebiotics is poorly documented, despite evidence of efficacy of particular probiotic strains in specific forms of IBD. METHODS: A case-control study comprising interviewer-administered questionnaires was conducted in IBD patients and healthy controls. Data regarding use and knowledge of probiotics and prebiotics, demographic, and clinical information were collected. RESULTS: In total, 334 participants (234 IBD, 100 controls) were interviewed. Significantly more IBD patients than controls had ever used probiotics to manage their health (Crohn's disease [CD] 43%, ulcerative colitis [UC] 51%, controls 21%, P < 0.001). Prebiotic use was negligible. On logistic regression analysis, having UC (odds ratio [OR] 4.30, 95% confidence interval [CI] 2.27-8.12) or CD (OR 3.05, 95% CI 1.66-5.60) were the strongest predictors of probiotic use. Within IBD patients the strongest predictor of probiotic use was current steroid use (OR 2.4, 95% CI 1.11-5.18). IBD patients had greater probiotic knowledge scores than controls (P = 0.003), although 20% of IBD probiotic users could not provide a definition of a probiotic. Less than half of IBD probiotic users discussed probiotic use with healthcare professionals, with commercial advertising being the primary source of information. CONCLUSIONS: Patients with IBD use probiotics to manage their health but frequently choose strains without evidence of efficacy in IBD. Patients rely on nonclinical sources of information and often do not disclose probiotic use to healthcare professionals. Conventional healthcare providers should inquire about probiotic use among their patients and offer evidence-based advice.

The restorative management of hypodontia with implants: 2. Planning and treatment with implants.

The first paper discussed the clinical features of patients with hypodontia. A range of treatment options were considered with examples given. In this second paper, the implant treatment option for patients is discussed in detail.

Accuracy of open tray implant impressions: an in vitro comparison of stock versus custom trays.

STATEMENT OF PROBLEM: The accuracy of an implant fixture-level impression is affected by the type of impression tray used. PURPOSE: The purpose of this in vitro study was to investigate the accuracy of open tray implant impressions comparing polycarbonate stock impression trays and rigid custom-made impression trays to make implant fixture-level impressions. MATERIAL AND METHODS: Gold cylinder pairs, splinted by gold bars (reference frameworks) were constructed on an aluminum typodont. Polyether impressions were made of 2 pairs of Brånemark 3.75-mm diameter fixtures mounted in an aluminium typodont, with 3 stock impression trays, 3 close-fit custom trays, and 3 spaced custom impression trays, by use of an open tray technique. The casts produced were assessed for accuracy by attaching the reference frameworks with alternate single screws and measuring the vertical fit discrepancy of these reference frameworks to the analogs within the working cast using a traveling microscope. Comparison of gap dimensions by tray type was performed with a nonparametric Kruskal-Wallis analysis of variance (ANOVA) followed by pair-wise Mann-Whitney U tests. To adjust for multiple comparisons in the post-ANOVA contrasts (P<.02). Comparison of gap dimensions between anterior and posterior regions were performed with Mann-Whitney U tests (P <.05). RESULTS: The results showed that the mean fit accuracy, as measured by vertical fit discrepancy, of casts from the stock trays (23 +/- 20 microm) were statistically significantly less (P<.001) than the spaced custom trays (12 +/- 10 microm) or close fit custom trays (11 +/- 10 microm). The difference in median gap size for analogs with a 20-mm separation was 10 microm. CONCLUSION: Within the limits of this in vitro study, rigid custom trays produced significantly more accurate impressions than the polycarbonate stock trays. The stock trays used in this study could not produce accurate impressions consistently. For analogs with a 20-mm separation, there was a difference in medians of 10 microm in accuracy between the stock and custom trays.

The restorative management of hypodontia with implants: I. Overview of alternative treatment options.

The first part of this paper discusses the clinical features of patients with hypodontia. Medical, social and clinical factors must be taken into account, along with risks and benefits, before a treatment plan can be recommended and implemented for a patient. An overview of treatment options are considered with examples. In the second part, implant treatment options will be discussed in detail.

The suitability of head-of-implant and conventional abutment impression techniques for implant-retained three unit bridges: an in vitro study.

This study compares the accuracy of master casts produced from impressions of implants using an abutment or a head-of-implant technique. The method used a Tandem Scanning Confocal Microscope to measure the dimensions of the gap between master casts produced by the two impression techniques and a custom made bridge. The median gap of 14 microns (interquartile range 10-17.9 microns) on the non-screwed side of the abutment impression was greater than the median gap of 7.5 microns (5-17.6 microns) for the head-of-implant impression and this difference was statistically significant (P < 0.005). In addition, the median gap on the screwed down side of the abutment impression of 10 microns, (6.3-12.1 microns) was greater than that of the head-of-implant of 5.5 microns (0.0-8.0 microns) and this difference was also statistically significant (P < 0.001). The head-of-implant impression produced a more accurate fit than the conventional abutment impression.