Porosity

The purpose of this study was to analyze, in an animal model, the histologic and biomechanical phenomena at the bone-implant interface of implants inserted with high torque (HT) as compared to low torque (LT) during the first 6 weeks of healing. Forty tapered-screw-form implants were placed in five hybrid sheep. The implant sites were placed in the mandible, using an extraoral approach; four were placed with HT (test: mean 110 Ncm) on one side and four were placed with LT (control: mean 10 Ncm) on the contralateral side. After 1, 2, 3, 4, and 6 weeks of healing, removal torque testing and resonance frequency analysis were performed and the animals were sacrificed for histologic examination. Implants from the HT group showed significantly higher bone apposition than implants from the LT group at all examined healing times. Similarly, removal torque was consistently higher for the HT as compared to the LT group. A significant loss of primary stability in the HT group was evident 7 day...

Absorbable hemostatic agents are commonly used after endoscopic sinus surgery (ESS). MPH (microporous polysaccharide hemospheres) is a novel hemostatic powder that is rapidly absorbed. The goal of this study was to examine the effects of MPH on bleeding after ESS. Randomized, controlled, single-blinded. Tertiary university hospital. Patients undergoing bilateral (symmetric) ESS for CRS by the same surgeon were randomized to unilateral treatment with MPH at surgical conclusion. The untreated opposite side served as a control. All patients received standard postoperative management. Patients completed symptom diaries using visual analog scales (VAS, scored out of 100) at baseline and through postoperative day (POD) 30. Outcomes including bleeding, pain, obstruction, and nasal discharge were recorded separately for left and right sides. Forty patients (19 men, 21 women) with an average age of 48.3 years were included. There were no complications, and all patients were discharged home the same day. The mean bleeding score on POD one for MPH-treated sides was 22.5 vs 39.0 for untreated controls (mean reduction 16.5, P < 0.0001, 95% CI -23.2 to -9.7). The scores for bleeding at baseline and at all other post-treatment days were not significantly different (P > 0.05). There were no other significant differences between MPH-treated and control sides in any other variables measured. The use of MPH after ESS results in significantly less bleeding in the early postoperative period with no increase in pain, obstruction, or nasal discharge. Patients treated with MPH follow a normal postoperative recovery otherwise.

The permeability and strength of pervious concrete depend on the particle sizes and proportions of the constituent materials of which the concrete is made of. In this paper, structural property and permeability of pervious concrete made with different coarse aggregate sizes is presented. For the different aggregate/cement ratio used in this study, coarse aggregate size 9.375 mm has higher compressive strength values compared to those made from 18.75 mm aggregate size while 18.75 mm aggregate size had higher permeability value compared to that of 9.38 mm. The average specific gravity of the two aggregates sizes used was 2.7. Aggregate/cement ratio of 6:1, 8:1 and 10:1 respectively were used to produce three different batches of fresh concrete using 18.75mm aggregate size and same ratios were used for 9.375mm coarse aggregate size to produce another three different batches. In each case, aggregate/cement ratio of 6:1 gave the highest compressive strength compared to other aggregate/ce...

ABSTRACT Foamed geopolymers were synthesised using a South African Class F coal fly ash (FA), sodium hydroxide (NaOH), and the novel foaming agent sodium hypochlorite (NaOCl) at slightly elevated temperatures (90 °C). The synthetic method has the advantage of maintaining control over foaming; the mixed and prepared cementitious slurry containing NaOCl is stable for at least 1 h at room temperature, thus, avoiding premature foaming of the slurry before moulding. In this study, the effect of NaOH/FA on the formation of foamed geopolymers was investigated at predetermined NaOCl/FA ratios (by weight). The NaOH/FA ratio was changed over the range of 0.16–0.24 at a constant NaOCl/FA composition of 0.50. Increasing NaOH/FA improved geopolymerisation up to a ratio of 0.20 and porosity up to a ratio of 0.22, after which geopolymerisation and porosity declined. These results were substantiated through XRD, SEM, FTIR, Raman analyses, mercury intrusion porosimetry, nitrogen adsorption/desorption, and helium density measurements. The formulations developed in this study may be used to fabricate materials suitable for application in construction as light weight fireproof insulation, internal walls or ceiling tiles.

The importance of breakfast cereal flakes (BCF) in Western diets deserves an understanding of changes in their mechanical properties and microstructure that occur during soaking in a liquid (that is, milk or water) prior to consumption. The maximum rupture force (RF) of 2 types of breakfast flaked products (BFP)--corn flakes (CF) and quinoa flakes (QF)--were measured directly while immersed in milk with 2% of fat content (milk 2%) or distilled water for different periods of time between 5 and 300 s. Under similar soaking conditions, QF presented higher RF values than CF. Soaked flakes were freeze-dried and their cross section and surface examined by scanning electron microscopy. Three consecutive periods (fast, gradual, and slow reduction of RF) were associated with changes in the microstructure of flakes. These changes were more pronounced in distilled water than in milk 2%, probably because the fat and other solids in milk become deposited on the flakes' surface hindering liqu...

PURPOSE The aim of this study was to obtain histometric measurements of bone and peri-implant mucosal tissue contact with implants of 2 sintered porous-surfaced designs. The "short-collar" design had a collar height (smooth coronal region) of 0.75 mm, while the "long-collar" model had a smooth coronal region of 1.8 mm. MATERIALS AND METHODS Implants (2 per side) were placed in healed mandibular extraction sites of 4 beagle dogs using a submerged technique. After 4 weeks of healing, they were uncovered and used to support fixed partial dentures for a 9-month period. After sacrifice, specimens were retrieved and nondemineralized sections were examined histometrically to determine the most coronal bone-to-implant contact (first BIC) using the microgap as a reference and standard mucosal parameters of "biologic width." RESULTS Significant (P = .001) differences in first BIC were found between designs (1.97 mm for long-collar versus 1.16 mm for short-collar ...

Dental implants are commonly used in daily practice; however, most surgeons do not really know the characteristics of these biomedical devices they are placing in their patients. The objective of this work is to describe the chemical and morphological characteristics of 14 implant surfaces available on the market and to establish a simple and clear identification (ID) card for all of them, following the classification procedure developed in the Dohan Ehrenfest et al (2010) Codification (DEC) system. Fourteen implant surfaces were characterized: TiUnite (Nobel Biocare), Ospol (Ospol), Kohno HRPS (Sweden & Martina), Osseospeed (AstraTech), Ankylos (Dentsply Friadent), MTX (Zimmer), Promote (Camlog), BTI Interna (Biotechnology Institute), EVL Plus (SERF), Twinkon Ref (Tekka), Ossean (Intra-Lock), NanoTite (Biomet 3I), SLActive (ITI Straumann), Integra-CP/NanoTite (Bicon). Three samples of each implant were analyzed. Superficial chemical composition was analyzed using X-ray photoelectro...

SUMMARY Disc-shaped specimens are frequently tested in order to establish an understanding of the properties of ceramic material. In this study three-dimensional finite element stress analysis has been used to investigate the loading characteristics of this shape of specimen and the effect of incorporating scratches and voids into its structure. The results indicated that stress increased as loading was carried out nearer to the centre of the specimen. The presence of cracks did not affect these stresses whereas the presence of a void resulted in a very high stress concentration.