Introduction The endosseous implants are important tools in modern orthopedic, odontostomatologycal and reconstructive surgery. Minipigs are relevant models to evaluate new biomatherials, due to their bone metabolic rate comparable to humans. Bone mineral density (BMD) is useful in clinical and experimental setting and correlates with measures of implant stability like insertion torque. High-resolution micro-computed tomography (micro-CT) is a non-destructive method that provides three dimensional bone-implant images and measurements of BMD. We investigated by micro-CT the osseointegration process in minipig. Methods Titanium implants with a scaffold made up of an innovative hybrid ceramo-polymeric nano composite material (hydroxyapatite/polyhydroxyletyl-methacrylate-nanosilica) were introduced into the left and right proximal tibial methaphysis of 4 minipigs (>18 months old, average body weight 70 kg). After 8 weeks, animals were sacrificed and specimens containing the implants were analyzed. An high resolution micro-CT imaging system (GE eXplore Locus, GE Healthcare, nominal spot size of 50 um, 1.8-mm Al-equivalent filtration, 110 X 55 mm CsI detector) was used. The acquisition protocol adopted was: x-ray tube voltage: 80 kVp; x ray tube current 450 uA; Number of Views:400; Frames Averaged:2; Exposure Time:100 ms, 45um pixel size; scan time 11min. Images were reconstructed using a modified Feldkamp algorithm and scaled into Hounsfield units (HU). An automatic thresholding technique that utilizes the Otsu method, was used to quantitative bone analysis (MicroView, 2.1.1). BMD (mg/cc) was measured in a volumetric region of interest (VOIs) near and at an equivalent distance between two median implants and in the controlateral cortical bone. We compared BMD values in the different sites by non-parametric analysis. Significance was set at P <0.05. 3D volume rendering images were performed using Osirix. Results The entity of osteointegration was visualized by three-dimensional recostruction. Perimplant BMD was less of 15% than controlateral cortical values, whereas we did not find significant differences between BMD around and at fixed distance between two implants. Conclusions Micro-CT is a non-destructive method for bone analysis that, unlike the conventional hystologic methods, does not need time consuming specimen preparation and specialized skills in microscopy. This method provides accurate three dimensional image analysis with informations on morphology and the implant stability. References Homolka P, et al. Radiology 2002;224(1):247-52. Beer A, et al. Clin Oral Implants Res 2003;14(5):616-20. Turkyilmaz I, et al. BMC Oral Health 2008; 8:32. doi: 10.1186/1472-6831-8-32. Depprich R, et al. Head Face Med 2008;4:30. doi: 10.1186/1746-160X-4-30. Tiainen H, et al. Int J Biomater. 2012:851264. doi: 10.1155/2012/851264. Epub 2012 Oct 3.
Micro-CT Analysis of Peri-implant bone in minipig model.
Gramanzini M;Gargiulo S;
2014
Abstract
Introduction The endosseous implants are important tools in modern orthopedic, odontostomatologycal and reconstructive surgery. Minipigs are relevant models to evaluate new biomatherials, due to their bone metabolic rate comparable to humans. Bone mineral density (BMD) is useful in clinical and experimental setting and correlates with measures of implant stability like insertion torque. High-resolution micro-computed tomography (micro-CT) is a non-destructive method that provides three dimensional bone-implant images and measurements of BMD. We investigated by micro-CT the osseointegration process in minipig. Methods Titanium implants with a scaffold made up of an innovative hybrid ceramo-polymeric nano composite material (hydroxyapatite/polyhydroxyletyl-methacrylate-nanosilica) were introduced into the left and right proximal tibial methaphysis of 4 minipigs (>18 months old, average body weight 70 kg). After 8 weeks, animals were sacrificed and specimens containing the implants were analyzed. An high resolution micro-CT imaging system (GE eXplore Locus, GE Healthcare, nominal spot size of 50 um, 1.8-mm Al-equivalent filtration, 110 X 55 mm CsI detector) was used. The acquisition protocol adopted was: x-ray tube voltage: 80 kVp; x ray tube current 450 uA; Number of Views:400; Frames Averaged:2; Exposure Time:100 ms, 45um pixel size; scan time 11min. Images were reconstructed using a modified Feldkamp algorithm and scaled into Hounsfield units (HU). An automatic thresholding technique that utilizes the Otsu method, was used to quantitative bone analysis (MicroView, 2.1.1). BMD (mg/cc) was measured in a volumetric region of interest (VOIs) near and at an equivalent distance between two median implants and in the controlateral cortical bone. We compared BMD values in the different sites by non-parametric analysis. Significance was set at P <0.05. 3D volume rendering images were performed using Osirix. Results The entity of osteointegration was visualized by three-dimensional recostruction. Perimplant BMD was less of 15% than controlateral cortical values, whereas we did not find significant differences between BMD around and at fixed distance between two implants. Conclusions Micro-CT is a non-destructive method for bone analysis that, unlike the conventional hystologic methods, does not need time consuming specimen preparation and specialized skills in microscopy. This method provides accurate three dimensional image analysis with informations on morphology and the implant stability. References Homolka P, et al. Radiology 2002;224(1):247-52. Beer A, et al. Clin Oral Implants Res 2003;14(5):616-20. Turkyilmaz I, et al. BMC Oral Health 2008; 8:32. doi: 10.1186/1472-6831-8-32. Depprich R, et al. Head Face Med 2008;4:30. doi: 10.1186/1746-160X-4-30. Tiainen H, et al. Int J Biomater. 2012:851264. doi: 10.1155/2012/851264. Epub 2012 Oct 3.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
