Six weeks after insertion of the scaffolds, the animals were given an over dose of an anesthetic injection and section blocks were obtained by cutting the mandible maintaining 10 mm of sound bone around the scaffolds. Cut sections were immediately fixed in 4% buffered formaldehyde and dehydrated in graded ethanol solutions using a dehydration system under agitation and vacuum, and the specimens were then defatted in xylene solution. Finally, the specimens were embedded in transparent chemically polymerized methyl methacrylate resin (methyl methacrylate 99%, Sigma-Aldrich, Steinheim, Germany). After polymerization, the specimens were cut along the long axis of the scaffolds using a diamond-coated disc rotating in a micro-sectioning system (Micracut 150 precision cutter, Metkon, Bursa, Turkey) followed by polishing using 800 grit silicon carbide paper. One hundred-micrometer-thick cut sections were stained using Stevenel’s blue and van Gieson picro-fuchsin. Histomorphometric analysis was performed using digital images obtained using a light stereomicroscope (Olympus BX 61, Hamburg, Germany) equipped with a high-resolution digital camera (E330, Olympus, Imaging Corp, Beijing, China).

Measurements were made by first calculating the pore volume on the images using digital tracing option of the software (white pores on the images), and the amount of new bone formation (mineralized tissue stained red) was calculated as a percent of the total pore volume (Olympus CellM & CellR, version 3.3, Olympus Soft Imaging Solutions).

Examiner reliability was cross checked by re-evaluating randomly selected digital images by another expert examiner. The recorded correlation coefficient ranged from 0.83 to 0.92, indicating high reliability for all measured parameters. The data obtained were expressed as mean and standard deviation values and were analyzed using Student’s t test (SPSS 15.0, SPSS, Chicago, IL).