Bone Reconstruction Using Two-Layer Porcine-Derived Bone Scaffold Composed of Cortical and Cancellous Bones in a Rabbit Calvarial Defect Model.

In this study, we aimed to investigate the bone regeneration efficiency of two-layer porcine-derived bone scaffolds composed of cancellous and cortical bones in a rabbit calvarial defect model. Four circular calvaria defects were formed on cranium of rabbit and were filled with block bone scaffolds of each group: cortical bone block (Cortical group), cancellous bone block (Cancellous group), and two-layer bone block (2layer group). After 8 weeks, new bones were primarily observed in cancellous parts of the Cancellous and 2layer groups, while the Cortical group exhibited few new bones. In the results of new bone volume and area analyses, the Cancellous group showed the highest value, followed by the 2layer group, and were significantly higher than the Cortical group. Within the limitations of this study, the cancellous and two-layer porcine-derived bone scaffolds showed satisfactory bone regeneration efficiency; further studies on regulating the ratio of cortical and cancellous bones in two-layer bones are needed.

Impact of duty ratio-controlled ion energy on surface roughness of silicon nitride films deposited using a SiH4-NH3 plasma.

The impact of duty ratio-controlled ion energy on the surface roughness of silicon nitride (SiN) films is examined as a function of the bias power and the duty ratio. Experimental ranges are 30-90 W and 20-80% for the bias power and the duty ratio, respectively. SiN films were deposited at room temperature using a SiH4-NH3 pulsed plasma. Atomic force microscopy was used to measure surface roughness. Investigation is detailed in view of a mean-surface roughness, a non-uniformity of surface height distribution, and using a prediction model. The prediction model was constructed using a neural network and a genetic algorithm. A decrease in the duty ratio results in an increase in the surface roughness, but a decrease in the non-uniformity. Correlation study revealed that the surface roughness was strongly related to the ion energy and the ion energy flux. The neural network model predicts the high ion energy as the most influential diagnostic parameter.

Gel-type autologous chondrocyte (Chondron) implantation for treatment of articular cartilage defects of the knee.

BACKGROUND: Gel-type autologous chondrocyte (Chondron) implantations have been used for several years without using periosteum or membrane. This study involves evaluations of the clinical results of Chondron at many clinical centers at various time points during the postoperative patient follow-up. METHODS: Data from 98 patients with articular cartilage injury of the knee joint and who underwent Chondron implantation at ten Korean hospitals between January 2005 and November 2008, were included and were divided into two groups based on the patient follow-up period, i.e. 13~24-month follow-up and greater than 25-month follow-up. The telephone Knee Society Score obtained during telephone interviews with patients, was used as the evaluation tool. RESULTS: On the tKSS-A (telephone Knee Society Score-A), the score improved from 43.52 +/- 20.20 to 89.71 +/- 13.69 (P < 0.05), and on the tKSS-B (telephone Knee Society Score-B), the score improved from 50.66 +/- 20.05 to 89.38 +/- 15.76 (P < 0.05). The total improvement was from 94.18 +/- 31.43 to 179.10 +/- 24.69 (P < 0.05). CONCLUSION: Gel-type autologous chondrocyte implantation for chondral knee defects appears to be a safe and effective method for both decreasing pain and improving knee function.

Surface morphology of SiN film deposited by a pulsed-plasma enhanced chemical vapor deposition at room temperature.

Silicon nitride (SiN) films were deposited by a pulsed plasma enhanced chemical vapor deposition system in a SiH4-NH3 chemistry. Surface morphology of SiN films at room temperature is first reported. Scanning electron microscope and atomic force microscopy were used for characterization. Radio frequency source power was varied from 200-800 W with an increment of 200 W. For each power, duty cycle was controlled as 40, 50, 70, 90%. Particularly, surface roughness was detailed in terms of a distribution of maximum pixel size or major pixel density, and a nonuniformity of pixel density. A consistent decrease in surface roughness with reducing duty cycle was observed in the ranges of 40-70% and 40-90% at 200 and 600 W, respectively. In contrast, surface roughness increased with reducing duty cycle at 800 W. Meanwhile, both maximum pixel size and distribution of major pixel density were highly correlated to surface roughness as a function of duty cycle at all powers. These two metrics are expected to effectively characterize the degree of surface densification as well as to support surface roughness variations.

Clinical evaluation of mandibular implant overdentures via Locator implant attachment and Locator bar attachment.

PURPOSE: The aim of this study was to evaluate the clinical findings and patient satisfaction on implant overdenture designed with Locator implant attachment or Locator bar attachment in mandibular edentulous patients. MATERIALS AND METHODS: Implant survival rate, marginal bone loss, probing depth, peri-implant inflammation, bleeding, plaque, calculus, complications, and satisfaction were evaluated on sixteen patients who were treated with mandibular overdenture and have used it for at least 1 year (Locator implant attachment: n=8, Locator bar attachment: n=8). RESULTS: Marginal bone loss, probing depth, plaque index of the Locator bar attachment group were significantly lower than the Locator implant attachment group (P<.05). There was no significant difference on bleeding, peri-implant inflammation, and patient satisfaction between the two denture types (P>.05). The replacement of the attachment components was the most common complication in both groups. Although there was no correlation between marginal bone loss and plaque index, a significant correlation was found between marginal bone loss and probing depth. CONCLUSION: The Locator bar attachment group indicates lesser marginal bone loss and need for maintenance, as compared with the Locator implant attachment group. This may be due to the splinting effect among implants rather than the types of Locator attachment.