[show abstract][hide abstract] ABSTRACT: The chemical and dimensional stability associated with suitable fracture toughness and propitious tribological characteristics make silicon nitride-based ceramics potential candidates for biomedical applications, mainly as orthopedic implants. Considering this combination of properties, silicon nitride components were investigated in relation to their biocompatibility. For this study, two cylindrical implants were installed in each tibia of five rabbits and were kept in the animals for 8 weeks. During the healing time, tissue tracers were administrated in the animals so as to evaluate the bone growth around the implants. Eight weeks after the surgery, the animals were euthanized and histological analyses were performed. No adverse reactions were observed close to the implant. The osteogenesis process occurred during the entire period defined by the tracers. However, this process occurred more intensely 4 weeks after the surgery. In addition, the histological analyses showed that bone growth occurred preferentially in the cortical areas. Different kinds of tissue were identified on the implant surface, characterized by lamellar bone tissue containing osteocytes and osteons, by a noncalcified matrix containing osteoblasts, or by the presence of collagen III, which may change to collagen I or remain as a fibrous tissue. The results demonstrated that silicon nitride obtained according to the procedure proposed in this research is a biocompatible material.
Journal of Biomedical Materials Research Part A 03/2008; 84(2):337-43. · 2.83 Impact Factor
[show abstract][hide abstract] ABSTRACT: Silicon nitride has demonstrated to be a potential candidate for clinical applications because it is a non-cytotoxic material and has satisfactory fracture toughness, high wear resistance and low friction coefficient. In this paper, samples of silicon nitride, which were kept into rabbits' tibias for 8 weeks, and the adjacent bone tissue were analysed by scanning electron microscopy in order to verify the bone growth around the implants and the interaction between the implant and the bone. Bone growth occurred mainly in the cortical areas, although it has been observed that the newly bone tends to grow toward the marrow cavity. Differences were observed between the implants installed into distal and proximal regions. In the first region, where the distance between the implant and the cortical bone is greater than in the proximal region, the osteoconduction process was evidenced by the presence of a bridge bone formation toward the implant surface. The results showed that silicon nitride can be used as biomaterial since the newly bone grew around the implants.
[show abstract][hide abstract] ABSTRACT: The objective of this study was to characterize calcium pyrophosphate material, evaluate its in vitro cytotoxicity, and assess its ability to induce bone formation. X-ray diffraction (XRD) was used to determine crystallinity and phases present in material. Serial dilutions of extracts, from 10-day dissolution tests in modified Eagle's medium, were exposed for 24 h to mouse fibroblasts and cytotoxicity assessed via viable staining. In vivo performance was determined by placing Ti screws with and without calcium pyrophosphate agglutinated with marrow adipose tissue in the tibiae of eight rabbits. New bone formation around test and control implants was evaluated histomorphometrically by using three fluorochrome labels: alizarin, calcein, and tetracycline. After 8 postoperative weeks, the animals were killed and specimens were retrieved and processed for fluorescence and light microscopic analysis. Calcium pyrophosphate showed no cytotoxicity and the XRD showed that the main phase of the analyzed sample corresponded to beta-calcium pyrophosphate. The largest fluorochrome labeling area occurred during the fourth and fifth postoperative weeks, in both control and experimental groups. Histologically, the bone neoformation occurred in regions where the calcium pyrophosphate was resorbed. The morphometric analysis showed implants placed with calcium pyrophosphate resulted in smaller polyfluorochrome labeling area (p < 0.05).
Journal of Biomedical Materials Research Part B Applied Biomaterials 02/2006; 76(2):373-80. · 2.31 Impact Factor
[show abstract][hide abstract] ABSTRACT: Oral reconstruction using osteointegrated implants are widely indicated nowadays. The implant bone anchorage is very important for its functional stability. Thus, ceramic biomaterials are widely used as coatings of the implant surfaces to accelerate local osteogenesis. The purpose of this study is to assess the biocompatibility and the osteoconduction of two types of calcium phosphate ceramics used as titanium dental implant coatings. These implants were installed in rabbit tibia during an 8-week healing period. The light and fluorescent microscopy observations showed that the materials are biocompatible and that they have osteoconductive activities.
[show abstract][hide abstract] ABSTRACT: Alcohol consumption affects bone metabolism by impairing osteoblast proliferation and by increasing osteoclastic activity. The purpose of this study was to evaluate bone formation in alcohol-fed rabbits following the insertion of dental titanium implants. Animals were fed with 20% ethanol sugarcane brandy pre- and postoperatively (group 1), preoperatively only (group 2), and with water as control (group 3). During the postoperative period, rabbits received doses of polyfluorochrome labels (i.e., alizarin, calcein, and tetracycline). Rabbits were killed 8 weeks after the implant insertion. The polyfluorochrome-labeled bone areas in rabbits with alcohol consumption in pre- and postoperative (group 1) and preoperatively only (group 2) were significantly less (P <.05) than in the control group (group 3). The percentage of direct bone-to-implant contact was significantly less in pre- and postoperative (49.5%) and preoperative-only (49.2%) groups than in the control group (64.7%) (P <.05). Alcoholic rabbits demonstrated significantly less bone density and direct bone-to-implant contact.
[show abstract][hide abstract] ABSTRACT: The purpose of this article is to evaluate the bone healing around 2 different dental implant surfaces after the lateralization surgery of the inferior alveolar nerve (IAN) during an 8-week healing period in rabbits, and to check if there is any interaction between the implants and the nerve.
The IAN lateralization was performed in an experimental rabbit model. Eight adult female rabbits (Oryctolagus cuniculus) underwent the surgical procedure, and 1 implant was placed on each side of the mandible while the nerve was lateralized. On both sides, the nerve was repositioned directly in contact with the implant surface. With the intention of obtaining comparative results, smooth titanium implants were installed on the right side, and blasted Al2O3 ones were placed on the left. During the healing period, bone tracers were administered subcutaneously to check different periods of bone ingrowth.
Histologic section, regardless of the studied surface, showed bone remodeling around the nerve, without contact between the nerve and the implanted surface. The bone blocks containing implants were histomorphometrically examined through computerized analysis, and the results obtained showed that the bone remodeling around the nerve occurred during the first weeks of healing. Through analysis of variance, the blasted Al2O3 implants showed at least 2.5-fold greater bone neoformation compared with the smooth titanium implants.
Our results showed that there was no significant difference in the healing process concerning the nerve between the 2 studied surfaces. No interaction was detected between the nerve and the implants.
Journal of Oral and Maxillofacial Surgery 10/2004; 62(9 Suppl 2):131-5. · 1.33 Impact Factor
[show abstract][hide abstract] ABSTRACT: The purpose of this study is to analyze the bone remodeling process after the placement of threaded implants with rough (RBM) and hydroxyapatite coated surfaces (HA) in rabbit tibias using polyfluorochrome sequential labeling. Histomorphometry was performed in order to quantify the amount of each label deposited during the healing period. This work demonstrates the possibility of periodic identification of apatite deposition during bone remodeling around titanium and ceramic implants. It has been concluded that the polyfluorochrome sequential labeling is an important tool for identification of bone remodeling after the insertion of titanium and ceramic implants inside rabbit tibias.