Arsenic release provided by MTA and Portland cement.

OBJECTIVE: The aim of the present study was to determine the release of arsenic from 2 gray Portland cements, a white Portland cement, and 2 MTAs (ProRoot and MTA-Angelus). STUDY DESIGN: The materials were manipulated and placed in plastic tubes, and the tubes were immersed in glass flasks containing water with grade reagent, pH 5.0. After 3 and 168 h, the water in which the material had been immersed was analyzed regarding the presence of arsenic by atomic absorption spectrophotometry with hydride generation. RESULTS: The levels of arsenic released were similar for Portland cements and MTAs, and were well below those considered to be harmful. CONCLUSIONS: MTA and Portland cements showed very low arsenic presence. The results suggest that MTAs and Portland cements are safe for use in clinical practice in terms of the presence of arsenic.     

Chemical analysis of powder and set forms of Portland cement, gray ProRoot MTA, white ProRoot MTA, and gray MTA-Angelus.

OBJECTIVE: To evaluate the chemical composition and crystalline structures of Portland cement, gray ProRoot MTA (gray MTA), white ProRoot MTA (white MTA), and gray MTA-Angelus. STUDY DESIGN: X-ray diffraction analysis was used to identify and characterize crystalline phases, and energy dispersive x-ray spectrometer was used to determine the chemical composition of the test materials. Both powder form and set form were examined. RESULTS: The crystalline structure and chemical composition of gray and white MTA were similar except for the presence of iron in gray MTA. Both were composed mainly of bismuth oxide and calcium silicate oxide. Portland cement was composed mainly of calcium silicate oxide and did not contain bismuth oxide. Gray MTA-Angelus had a lower content of bismuth oxide than ProRoot MTA. There were no noticeable differences in the chemical composition and crystalline structures between the powder and set forms of any of the material tested. CONCLUSION: Portland cement differed from the MTA by the absence of bismuth ions and presence of potassium ions. Gray MTA contained a significant amount of iron when compared with white MTA. In addition, gray MTA-Angelus had a lower content of bismuth oxide than ProRoot MTA.     

Experimental facial augmentation with hydroxyapatite cement

OBJECTIVE: To study the results of implantation of preformed hydroxyapatite (HA) disks and HA cement in onlay augmentation. METHODS: In this prospective study involving 16 adult New Zealand rabbits, HA disk and HA cement samples were implanted separately and together along the bony and cartilaginous nasal dorsum as well as over the supraorbital bone. Gross and histologic examinations of the implants were performed at intervals ranging from 3 to 24 months. RESULTS: There was no evidence of infection, adverse reaction, or implant extrusion in the 15 rabbits surviving the planned period. Grossly, all rabbits had prominent noses and supraorbital regions that were immobile on digital palpation. No measurable change in HA disk height and width was noted but there was a 15% decrease in height and width in the HA cement implant. Microscopically, preformed HA disks were found to be enclosed in a vascularized fibrous capsule. When disks were combined with HA cement, a vascular fibrous capsule was still noted around the implant but there was osteoconversion in the underlying cement layer. Used alone, HA cement underwent both osteoconversion and osteointegration. Neither the preformed HA disk with and without HA cement nor the HA cement alone elicited giant cell reaction or inflammatory changes. The HA cement alone was found to have microscopic fissures at the edges. CONCLUSION: This animal study suggests that preformed HA implants and HA cement, alone or in combination, can be used to augment the non-stress-bearing craniofacial skeleton.     

Genotoxicity and cytotoxicity of mineral trioxide aggregate and regular and white Portland cements on Chinese hamster ovary (CHO) cells in vitro.

OBJECTIVE: Recently, mineral trioxide aggregate (MTA) and Portland cement have been used in dentistry as root-end-filling materials. However, the reported results concerning the biocompatibility of these materials are inconsistent. The goal of this study was to examine the genotoxicity and cytotoxicity of MTA and Portland cements in vitro by the single-cell gel (comet) assay and trypan blue exclusion test. STUDY DESIGN: Chinese hamster ovary (CHO) cells were exposed to MTA and regular and white Portland cements at final concentration ranging from 1 to 1000 microg/mL for 1 h at 37 degrees C. RESULTS: All compounds tested did not show genotoxic effects in all concentrations evaluated. No significant differences (P > .05) in cytotoxicity were observed for all compounds tested. CONCLUSIONS: Taken together, our results suggest that MTA and Portland cements are not genotoxins and are not able to induce cellular death.     

The effect of liposome‐delivered prednisolone on collagen density,myofibroblasts, and fibrous capsule thickness around silicone breast implants in rats

Capsular contracture is a potential adverse effect of breast implants. An inflammatory reaction is most likely the origin of fibrosis around the implant. It is possible that some substances may act to prevent this inflammatory reaction. Thus, our goal was to evaluate the effectiveness of local depot prednisolone phosphate‐liposomes (PPL) on fibrous capsule formation around textured silicone breast implants. Shell prostheses (2 mL) were implanted in the right (plus PPL group) and left (plus saline solution, saline group) subcutaneous dorsum of 18 rats. In another 18 rats, the implants were positioned in the left of the back without any drug instillation (control group). In the PPL group, the capsule thickness (μm) and density (%) of collagen were significantly (p<0.0001) lower compared with the control group on days 35 and 90 postsurgery. Furthermore, in the PPL group, a significant reduction in myofibroblast count was observed on day 90 postsurgery (p<0.0001). In conclusion, a single dose of depot liposome‐delivered prednisolone was effective at impairing capsule formation around the silicone implant. The results suggest a strong local and weak systemic effect of PPL on the fibrous tissue around silicone implants. To our knowledge, no study has yet assessed the effect of PPL on silicone breast implants.     

In vivo evaluation of the biocompatibility of a new resin-based obturation system.

OBJECTIVE: The aim of this study was to evaluate the in vivo biocompatibility of the new resin-based Epiphany-Resilon root canal filling system after implantation in rat connective tissue. STUDY DESIGN: Thirty-six female Wistar albino rats, 9 months old, weighing 200 to 220 g, were used to evaluate the biocompatibility. Four subcutaneous pockets were created in the back of the rats, and each material (Resilon, gutta-percha, a Teflon tube containing Epiphany, and an empty Teflon tube) was implanted into a specific dorsal site. The empty Teflon tubes were used as control. After 1, 4, and 8 weeks, the implants were removed with the surrounding tissues. The inflammatory tissue reactions were graded after a histopathologic examination. RESULTS: At each time period, there was practically no difference in the reaction of all the implant materials (P > .05). The intensity of the reaction had diminished by the 4-week observation period, and this reduction continued through the 8-week observation period. CONCLUSION: All the tested materials showed an acceptable biocompatibility.     

Microcirculation disorders as the cause of capsular contraction after augmentative mammoplasty

Fragments of fibrous capsules removed during operations on account of III - IV degree fibrous capsular contraction around mammoimplant or prosthesis (oleoimplant) deformation were studied with light microscopy. Signs of lymphostasis were detected in all the layers of capsule at all the patients. Fibrous capsular contraction progresses due to dysbalance between volumes of areolar (boundary) and thick (basic) parts of capsule. This dysbalance may be caused by activation of inflammatory reaction at tissues surrounding implant after trauma of them, or by microcirculation disorders due to blockade of vessels with implants or tissue detritus.     

硅胶乳房假体表面改性的实验研究及CT评价

目的：研究乳房假体表面改性对减少纤维囊壁形成的影响及CT评价。方法：利用钴^60共辐射的方法把亲水性单体N-乙烯基吡咯烷酮(N-VP)接枝到硅胶乳房假体表面，改变其表面特性后植入兔的背部，以未经改性的正常假体作为对照组，隔一定时间通过组织切片及CT扫描的方法观察假体周围纤维囊壁的形成情况。结果：与对照组相比，改性后假体周围的炎症反应较轻，形成的纤维囊壁在各个时间段均薄于对照组；CT扫描显示术后8个月，改性的硅胶假体外形无明显改变，而未改性组外形显著改变。结论：在硅胶乳房假体表面接枝N-VP后可以有效地改善假体表面的组织相容性，减少周围纤维囊壁的形成。     

Titanium-coated polypropylene mesh (TiLoop Bra®)—an effective prevention for capsular contracture?

Background

Silicone implants have been used in breast augmentation for more than 45 years. Complications, in particular, capsular contracture, still occur with a high incidence. Titanium-coated polypropylene mesh (TCPM; TiLoop Bra®, pfm medical, Cologne, Germany) provides new opportunities for implant-based breast reconstruction. We investigated the influence of the surface of silicone implants on the formation of capsular contracture by comparing textured silicone with TCPM-covered smooth silicone implants.

Methods

Twenty textured silicone gel-filled (group A) and twenty TCPM-covered smooth silicone gel implants (group B) (Silimed®, Rio de Janeiro, Brazil) were implanted in female Wistar rats. After 60 days, the implants and capsules were extracted, and histological and immunohistochemical staining was performed. The double-blind evaluation of the capsules was performed by two examiners.

Results

We were able to detect a thinner, but stiffer, capsule and a less development of an inner synovia metaplasia layer as well as a lower vascularity in capsules around TCPM-covered silicone implants. We found a higher percentage of myofibroblasts within the capsule structure and more inflammatory cell infiltration.

Conclusions

The quality of capsule structure around both tested implants differs significantly. Although capsules around TCPM-covered implants presented were thinner, they integrated with the mesh in a rigid cage structure capsule with higher infiltration of inflammatory cells caused by a significant foreign body reaction. TCPM-covered silicone implants showed no apparent advantage in the reduction of capsular contracture. On the other hand, the indication for using this material as a supportive soft tissue structure can be confirmed. Level of Evidence: not ratable, experimental study.     

BMP induced inflammation: A comparison of rhBMP‐7 and rhBMP‐2

Concern has been raised because of reports of inflammatory swelling following the use of recombinant human bone morphogenetic protein‐2 (rhBMP‐2) and recombinant human bone morphogenetic protein‐7 (rhBMP‐7). The purpose of this study is to compare the inflammatory action of rhBMP‐7 with those of rhBMP‐2. ELISA assays (IL‐6, TNF‐α) were used to measure the cytokine response to different concentrations of rhBMP‐7 and ‐2. Recombinant human BMP‐7 was absorbed into absorbable collagen sponges and different amounts were implanted either subcutaneously (SC) or intramuscularly (IM) into the backs of rats. Using MRI and MIPAV software, we measured the degree of soft tissue edema at 3 h and at 2, 4, and 7 days postoperatively. After sacrificing rats on day 7 the inflammatory zone and mass were measured and the tissue examined histologically. Soft tissue edema after rhBMP‐7 and rhBMP‐2 implantation was dose‐dependent and peaked at 3 h for the subcutaneous implants and at 2 days for the intramuscular implants. RhBMP‐7 was associated with a significantly smaller soft tissue edema volume than was rhBMP‐2 only at the highest dose (20 µg/ml). Both rhBMP‐2 and rhBMP‐7 triggered dose‐dependent inflammatory reactions. Compared to rhBMP‐2, rhBMP‐7 is associated with somewhat smaller soft tissue edema volumes. Although rhBMP‐7 is associated with an inflammatory reaction leading to soft tissue edema, at high doses this response is significantly less than that seen with rhBMP‐2. Our animal model can be used to test materials that could ameliorate this reaction. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1985–1994, 2012     

Osseous penetration rate into implants pretreated with bone cement

The titanium bone growth chamber consists of two titanium disks held together by two screws. At the level of the intersection between the disks, a 1 mm wide canal penetrates the implant. After implantation, in e.g. the rabbit, tibial metaphysis bone and vessels will grow through this canal, the contents of which are collected four weeks after surgery. Microradiography and a computer-based analysis give a numerical representation of the amount of newly formed bone in the canal. When the bone ingrowth into two identical titanium implants, one inserted in the left and the other in the right tibia, was compared, only small and insignificant differences were found in the same animal. However, when one animal was compared to another, greater differences in the bone-forming capacity were found, in spite of the fact that the rabbits were controlled with respect to race, age and sex. The osseous penetration rate into titanium canals was compared to the bone ingrowth in equally sized pipes of polymerized acrylic cement which had been inserted in the titanium chamber. In these cases there was significantly less bone formed in the cement pipes compared to the titanium controls. Poor biocompatibility of the cement compared to titanium is suggested to be one factor responsible for the reduced bone formation in the cement environment. This may be one reason for the fibrous tissue capsule generally seen around cemented implants.     

Combined bone allograft and adipose-derived stem cell autograft in a rabbit model

Currently available options for the repair of bony defects have substantial limitations. Much work has looked to the possibility of engineering bone using stem cells. These tissue-engineering efforts have focused on calvarial defect models, which have the advantages of minimal load-bearing and a large surface area. This study aims to solve the somewhat more challenging problem of repairing segmental bony defects such as those of the mandible and long bones. Four groups of decellularized bone tubes with cortical perforations were implanted subcutaneously in a rabbit model: empty bone tubes, bone tubes containing fibrin glue alone, bone tubes containing fibrin glue and freshly isolated autologous adipose-derived stem cells (ASCs), and bone tubes containing fibrin glue and predifferentiated autologous ASCs. Results showed a foreign body response characterized by fibrous capsule formation with minimal angiogenesis and no evidence of osteoblastic activity. Substantial changes are needed if this model is to become viable.     

Late hematoma after aesthetic breast augmentation with saline-filled,textured silicone prosthesis

Late, progressive enlargement of the breast after augmentation mammaplasty is an extremely rare complication. We present two cases of late capsular hematoma after augmentation mammaplasty with saline-filled, textured silicone implants. The MRI and C-T scan both clearly showed fluid accumulated within the capsule in one case. In this patient, we examined the interior of the fibrous capsule endoscopically, finding no persistent bleeding source. However, the inner lining had granulated tissue with new capillary ingrowth. After replacement with smooth-surface prostheses, neither patient had recurrence of the complication. No identifiable etiology could be demonstrated, however, the breakdown of an eroded capsular artery is suspected, caused by friction between the rough surface of the textured prosthesis and the fibrous capsule.     

The Influence of External Ultrasound on the Histologic Architecture of the Organic Capsule Around Smooth Silicone Implants: Experimental Study in Rats

BACKGROUND: Capsular contracture is the main complication related to breast silicone implants, and its prevention remains a medical challenge. The authors present experimental research examining the effect of external ultrasound on the formation and contracture of peri-implant capsules. METHODS: In this study, 42 male Wistar rats had a 2-mm smooth surface implant placed in a dorsal submuscular pocket. They then were separated into "ultrasound" and "control" groups that received repeated external applications either with or without the ultrasound power on. Ultrasound applications were given three times a week for a period of 90 days. After that, both groups were housed under the same conditions with no application scheduled. Five animals of each group, killed at 30, 60, 90, and 180 days, had their implants removed along with the capsule, which received a special histologic preparation via annular sectioning that provided wide circumferential observation of the capsular tissue. Sections were stained with hematoxylin/eosin stain, Masson's trichrome stain, and Pricrosirius Red stain for regular microscopic evaluation under normal and polarized light. RESULTS: Histologic data showed that capsules from the ultrasound and control groups had statistically significant differences. Ultrasound application developed a capsular architecture similar to that shown within textured silicone implants, and its effect had an early definition with subsequent stabilization. CONCLUSION: The authors conclude that early and repeated external ultrasound application enhances the thickness, cellular count, and vascularity of smooth silicone capsular tissue, whereas it diminishes the pattern of parallel orientation of collagen fibers.     

Microtopography and Soft Tissue Response

Implants placed in soft tissue evoke a foreign body reaction. Polymeric implants having smooth surfaces, such as silicone rubber implants, develop a nonadherent fibrogranulous tissue capsule which contracts over time and stiffens. Conventional porous implants, such as those made from textiles, usually have pores larger than 20 μm and they become infiltrated with inflammatory tissue. The in vivo cell reaction to polymeric surfaces having pores smaller than 10 μm has not been investigated systematically. In this study the histocompatibility of materials having mean pore diameters from 0.4 to 10 μm was assessed. A material available with several different defined pore sizes Versapor filter material) was tested in vivo to determine relation between pore size and qualitative tissue response. Silicone-coated samples were also tested to determine the dependence of the observed tissue response on the implant surface chemistry. Results showed nonadherent, contracting capsules around implants having pore diameters smaller than 0.5 μm. Implants with pores ranging from 1.4 to 1.9 μm evoked thin, tightly adherent fibrous capsules without inflammatory cells. Porosities of 3.3 μm and larger became infiltrated with inflammatory tissue. Results indicate that the obsexrved tissue response is predominantly dependent on implant surface topography and that variation in implant material may have little effect. It is concluded that a defined surface topography of 1 to 2 pm appears to allow direct fibroblast attachment to the surface independent of its chemical or electrochemical nature. Attached fibro-blasts then produce a minimal connective tissue response to the implant and prevent or diminish the presence of inflammatory cells at the implant/tissue interface.     

Microtopography and soft tissue response

Implants placed in soft tissue evoke a foreign body reaction. Polymeric implants having smooth surfaces, such as silicone rubber implants, develop a nonadherent fibrogranulous tissue capsule which contracts over time and stiffens. Conventional porous implants, such as those made from textiles, usually have pores larger than 20 microns and they become infiltrated with inflammatory tissue. The in vivo cell reaction to polymeric surfaces having pores smaller than 10 microns has not been investigated systematically. In this study the histocompatibility of materials having mean pore diameters from 0.4 to 10 microns was assessed. A material available with several different defined pore sizes Versapor filter material) was tested in vivo to determine relation between pore size and qualitative tissue response. Silicone-coated samples were also tested to determine the dependence of the observed tissue response on the implant surface chemistry. Results showed nonadherent, contracting capsules around implants having pore diameters smaller than 0.5 microns. Implants with pores ranging from 1.4 to 1.9 microns evoked thin, tightly adherent fibrous capsules without inflammatory cells. Porosities of 3.3 microns and larger became infiltrated with inflammatory tissue. Results indicate that the observed tissue response is predominantly dependent on implant surface topography and that variation in implant material may have little effect. It is concluded that a defined surface topography of 1 to 2 microns appears to allow direct fibroblast attachment to the surface independent of its chemical or electrochemical nature. Attached fibroblasts then produce a minimal connective tissue response to the implant and prevent or diminish the presence of inflammatory cells at the implant/tissue interface.     

A new absorbable pressure-equalizing tube.

OBJECTIVE: We investigated pressure-equalizing (PE) tubes made of biodegradable, absorbable material in an animal model. METHODS: PE tubes, made of poly-bis(ethylanate)phosphazene (PBE) were inserted in 55 ears of 28 Hartley guinea pigs, with survival times of 10, 30, and 60 days after tube insertion. In vivo reactions between the PBE-PE tube and the tympanic membrane (TM) were studied. Tubes, TMs, and middle ears were examined by scanning electron microscopy and light microscopy. RESULTS: There was neither infection nor an inflammatory reaction to the tube within the middle ear in any animal. At 30 days, 53% of the tubes had disintegrated. At 60 days, tubes were still functioning in the 25% of ears. CONCLUSION: More research must be performed before these new PBE PE tubes can be considered for clinical use. Nonetheless, these tubes are promising. The disintegration rate can be controlled by varying the formulation of the polymer, so treatment can be adjusted to the needs of each patient.     

Expression of cyclooxygenase-2 in the periprosthetic capsule surrounding a silicone shell implant in the rat

Prosthetic breast implants are used frequently for both aesthetic and reconstructive purposes. Histologically, the normal tissue response to silicone implants typically involves an inflammatory infiltrate that consists initially of macrophages, and later consists of fibroblasts, myofibroblasts, and lymphocytes. To characterize further the nature of the inflammatory response to silicone breast implants, the authors evaluated the expression of the enzyme cyclooxygenase-2 (COX-2) by the tissues and cells of the breast capsule after silicone augmentation in an animal model. COX-2 is an inducible enzyme that is expressed primarily in response to inflammatory stimuli and mediates the production of prostaglandins that support the inflammatory process. Fifty-nine animals at five time points were evaluated. Specifically, on days 4, 7, 14, 28, and 80 the authors identified cytoplasmic COX-2 expression in each of the three cell types of interest, including endothelial cells, macrophages, and fibroblasts. Selective COX-2 inhibiting agents may be an appropriate pharmacological intervention for modulating the formation of periprosthetic capsules.     

复合rhBMP-2可注射磷酸钙骨水泥在椎体成形术中应用的实验研究

目的 探讨自主研发的复合rhBMP-2可注射磷酸钙骨水泥(复合材料)替代注射型聚甲基丙烯酸甲酯(PMMA)应用于猕猴椎体成形术的可行性.方法 将4只成年猕猴分为Ⅰ、Ⅱ两组,每组2只.每组猕猴T10～L7的20个椎体经皮穿刺,按处理方法不同分为复合材料组(A组,8个椎体)、可注射型PMMA组(B组,6个椎体)和手术空白对照组(C组,6个椎体).分别于术后即刻和术后1、2,4、6个月行放射学检查.Ⅰ组于术后2个月、Ⅱ组于术后6个月处死,取出单个椎体,每个椎体取含材料骨样本2份,1份用于光镜检查,另1份用于扫描电镜.观察两种材料强化椎体的早期和后期效果和变化.结果 A组2个月时材料部分降解,未见界面缝隙、纤维增生、炎性浸润或硬化骨痂现象,大量类骨质形成并长人材料,可见新生血管;6个月后大部分材料吸收完全,大部分软骨钙化形成成熟骨组织,有完整的骨小梁及哈佛系统.B组2个月时未见材料降解,中度炎性浸润,纤维组织膜包裹,界面缝隙明显,未见新骨生长;6个月时,炎性浸润消失,纤维界膜变薄,界面缝隙变窄,仍无材料降解和新骨生长.C组2个月后椎体骨隧道被新生骨质填充,骨小梁排列紊乱,边界硬化骨痂形成;6个月后,骨小梁排列整齐,边界骨痂消失,不能辨认,骨重建完成.结论 复合rhBMP-2的注射型磷酸钙骨水泥植入椎体后能够获得良好的诱导生长活性,材料降解和新骨替代同步,周期接近于正常椎体的骨愈合,可望替代PMMA获得椎体成形后早期和远期更好的组织学效果.