Comparison of shear bond strength and ARI of four different adhesive systems used to bond molar tubes: An in vitro study.

OBJECTIVE: The purpose of this in vitro study was to determine and compare the shear bond strength and ARI score of one traditional etch-and-rinse adhesive system serving as control, with those of two other all-in-one adhesives but with enamel acid etching preceding their application, and of one new 8th generation all-in-one bonding agent combined with a traditional adhesive used to bond stainless steel buccal tubes to molar teeth. MATERIAL AND METHODS: Four groups of teeth were formulated according to the adhesive system used to bond the tubes on the molars. Shear bond strength was measured using a universal testing machine (Hounsfield, UK). After debonding, each enamel surface was imaged using Inspex HD l080p Vesa camera (Ash Technologies Ltd., Ireland) to determine the ARI score. RESULTS: The mean SBSs in MPa for the four groups were respectively: A: 9.640 (±3.69), B: 10.261 (±3.03), C: 9.689 (±2.48), D: 8.412 (±3.02). No statistically significant differences were neither found through one-way ANOVA to exist between the group means (P: 0.715), nor for the ARI score frequence through Chi2 (P: 0.534). Maxcem Elite showed four and G-Premio Bond zero instances of enamel fracture. CONCLUSIONS: 1. SBSs of all adhesives and ARI score distributions did not present any significant differences when used to bond stainless steel molar tubes. 2. All adhesives presented with acceptable shear bond strengths for clinical use. 3. Maxcem Elite under the tested conditions presented the greatest and G-Premio the least number of enamel fractures.

Preparation of morselised bone for impaction grafting using a blender method.

Impaction bone grafting is a method of restoring bone stock to patients suffering significant bone loss due to revision total hip surgery. The procedure requires morselised bone (MB) to be impacted into the site of bone loss in order to stabilise the prosthesis with the aim of the long term resorption and reintegration of the impacted bone graft. Currently, the method for producing MB requires the use of expensive surgical bone mills or manually-intensive rongeurs that can produce a limited variety of particle sizes and may have a low throughput. This study examines the potential to produce suitable MB using a domestic blender. The method produces a wide range of particle sizes without the need for an adjustment of the system. It was found through packing modelling that this particle distribution resulted in reduced initial graft porosity and thus a theoretical potential to increase the graft stiffness and ability of the graft to stabilise a prosthesis in comparison to a manually prepared roughly cut morselised bone samples. Mechanical testing confirmed the increased mechanical performance of the graft through both impaction testing and subsidence testing. The blended MB was found to exhibit greater graft stiffness under the same impaction conditions. The graft was also found to have subsided less in comparison to the rough cut, less well graded MB. Scanning electron imaging also confirmed the retention of the trabecular structure necessary for revascularisation and host bone ingrowth. In conclusion, the blender method offers a rapid and cheap way of obtaining morselised bone with favourable particle size distribution, particle morphology and mechanical properties with preservation of the bone trabecular structure.

The use of hardened bone cement as an impaction grafting extender for revision hip arthroplasty.

Impaction bone grafting is a method of restoring bone stock to patients who have suffered significant bone loss due to revision total hip surgery. The procedure requires morsellised cancellous bone (MCB) to be impacted into the site of bone loss in order to stabilise the prosthesis with the aim of long term resorption and reintegration of the impacted bone graft. Due to financial cost and the potential to transmit disease, the use of supplementary material, known as an extender, is frequently used to increase the graft material volume. This study investigates the use of hardened Hydroset (Stryker Corp, MA, USA), an injectable bone cement (IBC), as an extender material and compares the performance of the IBC in different weight percent inclusions to a commercially available bone graft extender (GCP, BoneSave, Stryker Corp, MA, USA). The surgical impaction procedure was standardised and samples were evaluated in terms of graft stiffness and height. It was observed that 30wt% IBC extended samples had significantly improved graft stiffness (p = 0.02) and no significant different in height (p = 0.067) over a 100% MCB control sample. Cyclic loading, representative of gait, found that the IBC subsided similarly to the commercial bone substitute in wt% above 10%. Shear testing of the impacted grafts showed no significant differences between GCP and IBC with impaction forces determining the shear parameters of impacted grafts. The effects of the impaction and cyclical loading procedures on extender particle sizes was assessed via particle size analysis. It was found that the IBC extended samples demonstrated reduced friability, evident in the better retention of particle size as a result of both impaction and gait representative loading compared to that of the GCP samples. This indicates a potential reduction in issues arising from small particle migration to joint surfaces. Scanning electron microscopy of the MCB particles with both GCP and IBC as extenders showed retention of the porous trabecular structure post-testing which is essential for revascularisation and bone growth into the graft.

The colonization history of British water vole (Arvicola amphibius (Linnaeus, 1758)): origins and development of the Celtic fringe.

The terminal Pleistocene and Early Holocene, a period from 15 000 to 18 000 Before Present (BP), was critical in establishing the current Holarctic fauna, with temperate-climate species largely replacing cold-adapted ones at mid-latitudes. However, the timing and nature of this process remain unclear for many taxa, a point that impacts on current and future management strategies. Here, we use an ancient DNA dataset to test more directly postglacial histories of the water vole (Arvicola amphibius, formerly A terrestris), a species that is both a conservation priority and a pest in different parts of its range. We specifically examine colonization of Britain, where a complex genetic structure can be observed today. Although we focus on population history at the limits of the species' range, the inclusion of additional European samples allows insights into European postglacial colonization events and provides a molecular perspective on water vole taxonomy.