Tissue response around silicon nitride implants in rabbits

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.

Ceramics and ceramic coatings in orthopaedics

“…Anderson et al showed osseous penetration of up to 3 mm in ∼72% porous Si 3 N 4 with excellent vascularization twelve weeks after implantation in an ovine model [105]. Similar studies by Guedes e Silva et al showed good boney apposition for Si 3 N 4 samples in rabbits evaluated eight weeks after implantation [103,104]. In Wistar rats, Webster et al compared the osseointegration of Si 3 N 4 , PEEK, and titanium, reporting that Si 3 N 4 had improved osseointegration over the other two biomaterials at alltime points up to 3 months post-operatively, both under aseptic conditions and when implants were pre-inoculated with 10 4 S. epidermidis [106].…”

“…Si 3 N 4 has been shown to be biocompatible, possessing favorable cell interaction characteristics [83,84,[97][98][99][100][101][102]. These and other studies indicate that porous or unpolished Si 3 N 4 osteointegrates with adjacent bone [102][103][104][105][106] and exhibits bacteriostasis [106,107] . In its dense and polished form, it has been shown to produce implants with exceptionally low wear rates [108][109][110][111][112][113][114][115][116][117][118].…”

Surface topography of silicon nitride affects antimicrobial and osseointegrative properties of tibial implants in a murine model

“…Si 3 N 4 is a synthetic nonoxide ceramic that is used in many industrial applications, and has been investigated or adapted as a biomedical material since 1989. 10,12,[36][37][38][39][40][41][42] The rationale for using Si 3 N 4 -based implants in skeletal reconstruction is based on its favorable combination of mechanical strength, microstructure, and cytotoxicity. 12,41 Polished and porous implants made of Si 3 N 4 have shown encouraging outcomes in spine and maxillofacial surgery.…”

Bone ingrowth into porous silicon nitride

“…When viewed under CT and MRI, silicon nitride generates no artifacts11 and is semitransparent under X‐ray 4. Multiple studies have evaluated local and systemic biological responses to silicon nitride in cell culture and animal models and have found it to be biocompatible 12–19. Previous studies have reported the successful use of silicon nitride implants as bone void fillers16 and osteofixation plates17 in animals, and in humans as intervertebral body spacers 19…”

“…4 Multiple studies have evaluated local and systemic biological responses to silicon nitride in cell culture and animal models and have found it to be biocompatible. [12][13][14][15][16][17][18][19] Previous studies have reported the successful use of silicon nitride implants as bone void fillers 16 and osteofixation plates 17 in animals, and in humans as intervertebral body spacers. 19 Because of this combination of mechanical and imaging properties, implants made of silicon nitride have the strength to support biomechanical loads and may allow more effective postoperative evaluation of the bone-implant interface.…”