Initial healing in the dog of submerged versus non‐submerged porous‐coated endosseous dental implants

It has previously been reported that porous‐coated root form endosseous dental implants, became well integrated when used in the traditional 2‐stage surgical approach. In this study, the placement of the implant in a 1‐stage (non‐submerged)technique was to be explored. Implants were placed in the mandibles of dogs, and 2 designs were used differing only in that one (experimental) had a 3mm transgingival extension, permitting it to be exposed lo the oral cavity from the outset. 12 (3 per animal) non‐submerged implants were placed on I side of 4 beagle dogs and 12 control (submerged) implants were placed contralaterally. All implants were allowed to heal for 6 weeks, after which histological preparations were made. 2 of 12 non‐submerged implants were lost due to post‐operative complications: otherwise, all implants healed uneventfully. Histomorphometric analysis revealed bone‐implant contact, as assessed by absolute bone contact (ABC) and contact length fraction (CLF). to be greater for the submerged design, suggesting that bone healing may be delayed with the non‐submerged approach. As well. at this early stage of healing, for both implant designs, ABC and CLF were significantly greater on proximal than on buccal and lingual aspects.     

Improved anchorage in osteoporotic vertebrae with new implant designs.

The goal of our study was to evaluate two newly developed implant designs and their behavior in terms of subsidence in lumbar vertebral bodies under cyclic loading. The new implants were evaluated in two different configurations (two small prototypes vs. one large prototype with similar load-bearing area) in comparison to a conventional screw-based implant (MACS TL). A pool of 13 spines with a total of 65 vertebrae was used to establish five testing groups of similar bone mineral density (BMD) distribution with eight lumbar vertebrae each. In additional to BMD assessment via dual-energy X-ray absorptiometry, cancellous BMD and structural parameters were determined using a new generation in vivo 3D-pQCT. The specimens were loaded sinusoidally in force control at 1 Hz for 1000 cycles at three load levels (100, 200, and 400 N). A survival analysis using the number of cycles until failure (Cox regression with covariates) was applied to reveal differences between implant groups. All new prototype configurations except the large cylinder survived significantly longer than the control group. The number of cycles until failure was significantly correlated with the structural parameter Tb.Sp. and similarly with the cancellous BMD for three of five implants. In both large prototypes the cycle number until failure significantly correlated with the preoperative distance to the upper endplates. Although the direct relationship between bone structure or density and mechanical breakage behavior cannot be conclusively proven, all the prototypes adapted for poor bone structure performed better than the comparable conventional implant.     

In vitro characterization of peptide-modified p(AAm-co-EG/AAc) IPN-coated titanium implants.

Interpenetrating polymer networks (IPNs) of poly(acrylamide-co-ethylene glycol/acrylic acid) [p(AAm-co-EG/AAc)] functionalized with an -Arg-Gly-Asp- containing peptide derived from rat bone sialoprotein [bsp-RGD(15)] were grafted to titanium implants in an effort to modulate osteoblast behavior in vitro. Surface characterization data were consistent with the presence of an IPN, and ligand density measurements established that the range of peptide density on the modified implants spanned three orders of magnitude (0.01-20 pmol/cm2). In vitro biological characterization of the modified implants employing the primary rat calvarial osteoblast (RCO) model resulted in the identification of a critical ligand density (0.01implants compared to the base titanium and other control surfaces. The observed effects were attributed to specific interactions with bsp-RGD(15) and support the concept that peptide-modified implants can enhance the kinetics of differentiation of the cells they contact. These results suggest that in vivo biological performance evaluation of these biomimetic implant surfaces is merited.     

Model Features of a Cardiac lontophoretic Drug Delivery Implant

Pharmaceutical Research -     

Resection and augmentation of Bichat's fat pad in facial contouring

Summary The Bichat's fat pad (Corpus adiposum buccae) is of great significance in facial contouring. Resection of major parts of this fat pad results in hollow cheeks and in accentuation of the zygoma. On the other hand, hypoplasia or shrinkage of this fat pad can be augmented by means of silicone implants for improved aesthetic results.     

Medpor义眼座置入同期放置钛钉治疗眼眶凹陷畸形

目的探讨Medpor义眼座植入同期放置钛钉治疗眼球摘除术后眼眶凹陷畸形的有效性和可行性。方法眼球摘除同期置入Medpor义眼座患者80例，随机分为钛钉Ⅰ期置入组和Ⅱ期置入组，每组各40例。比较两组患者术中、术后出现的并发症和患者对义眼活动度和外观的满意程度。结果40例Ⅰ期置入患者术中有37例在术后2～6周时钛钉尾端自发性暴露，只有3例患者需要剪开结膜使钛钉尾端暴露。术后出现并发症者共37例，占46％：其中Ⅰ期置入组17例，Ⅱ期置入组加例，两者差异无统计学意义（P=0．501）。所有患者对其外观和活动度满意，其中Ⅰ期置入组非常满意36例，比较满意4例；Ⅱ期置入组非常满意34例，比较满意6例，两者差异无统计学意义（P=0．502）。结论Medpor义眼座置入同期放置钛钉治疗眼球摘除术后眼眶凹陷畸形，是一种安全有效的手术方法，同时患者避免了再次手术的痛苦。     

Evaluation of BioCorkscrew and Bioknotless RC suture anchor rotator cuff repair fixation: an in vitro biomechanical study

This in vitro biomechanical study used cadaveric specimens to compare the rotator cuff repair fixation provided by BioCorkscrew and Bioknotless RC suture anchors. Three cm wide by 1-cm long full-thickness supraspinatus defects were repaired using either two BioCorkscrew suture anchors with combined vertical and horizontal mattress sutures (n = 7) or three Bioknotless RC suture anchors with simple sutures (n = 7). Therefore, the BioCorkscrew suture anchor group had two sutures per anchor (four total sutures), while the Bioknotless RC suture anchor group had one suture per anchor (three total sutures). Two-phase cyclic (5–100 N, 1,000 cycles and 5–180 N, 2,000 cycles) and load to failure tests (31 mm/s) were performed. Non-parametric statistics were used to compare group differences (P < 0.05). All of the BioCorkscrew group specimens (seven of seven) completed the two phase cyclic test regimen without failure or gapping ≥ 5 mm, compared to only three of seven of the Bioknotless RC group (Fisher’s Exact test = 0.03). Groups did not differ for repair site gapping during the 5–100 N cyclic test phase (Fisher’s Exact test = 0.77), however more of the Bioknotless RC group displayed gapping ≥ 5 mm during the 5–180 N cyclic test phase than the BioCorkscrew group (P = 0.02). The BioCorkscrew group also displayed greater yield load during load to failure testing (492.2 ± 204 N vs. 296.4 ± 155 N, P = 0.03). In this in vitro biomechanical study, the BioCorkscrew group with combined vertical and horizontal mattress sutures displayed greater cyclic test survival, less repair site gapping, and superior yield load compared to the Bioknotless RC group with simple sutures. These results in human cadaveric rotator cuff-humerus specimens suggest better immediate post-operative repair site strength and a reduced need for post-operative restrictions. Clinical studies are needed to determine how these rotator cuff repair modes withstand the forces of early rehabilitation and activities of daily living that potentially influence patient outcomes.     

First clinical experiences with an implantable bone conduction hearing aid at the University of Amsterdam

Summary A transcutaneous bone-conduction hearing aid was implanted in 11 patients who were not suitable for transcranial sound amplification. Audiological and surgical selection criteria were followed strictly. One device had to be explanted and minor revision surgery was needed in two cases for skin irritation and scarring. In general the aids were well tolerated but the amplification power of the external device proved to be insufficient in some patients, in whom bone conduction levels were on the borderline of the selection limits. Correspondence to: W.A. Dreschler     

Progressive peri‐implantitis. Incidence and prediction of peri‐implant attachment loss.

The aim of this prospective study was to characterize an implant patient population exhibiting clinical signs of peri‐implantitis and to determine subsequently the incidence of progressive attachment loss. The predictive values of diagnostic parameters were evaluated. 25 patients with 54 endosseous implants that had been loaded for 41±15 months were included in the study. Clinical parameters included the assessment of plaque, bleeding on probing, probing depth, attachment levels, and Periotest® values. Probing measurements were performed in duplicate by means of a controlled force electronic probe (Periprobem). Peri‐implant crevicular fluid samples were collected and assayed for neutral proteolytic enzyme (NPE) activity (Periocheck®). Analysis of duplicate baseline probing data revealed a high degree of reproducibility (mean difference: 0.1±0.3mm). A minimum threshold of 1.0mm (>3×S.D.) loss of probing attachment was chosen to classify a site as positive for breakdown. Alternatively, the tolerance method was employed to identify sites with progressive attachment loss. After 6 months, irrespective of the analytical method, 6 percent of all sites (in 19% of the implants) and 28% of the patients had experienced further per attachment loss. There were significant differences ( p <0.05) in mean plaque (73% vs. 45%) and NPE (36% vs. 12%) scores between patients with progressive peri‐implantitis and those with stable peri‐implant conditions. Both bleeding on probing and the NPE‐test were characterized by high negative predictive values, and thus negative scores can serve as indicators for stable peri‐implant conditions. For monitoring peri‐implant health during recall visits, attachment level recordings with a controlled force electronic probe in conjunction with enzymatic diagnostic tests of the host response can be recommended.     

种植牙手术的导向模板定向法临床研究

本文介绍了用于人工牙根种植手术的一种导向模板定向法。该导向模板由圆柱形金属定向杆、导向钛管、负压成型的塑料牙列套及自凝塑料增强基托组成。临床应用35例.效果满意。