Wound healing of osteotomy defects prepared with piezo- or conventional surgical instruments in the rabbit

Abstract

Aims: To evaluate and compare the wound healing process following osteotomies performed with either conventional rotary burs or piezoelectric surgery in a rabbit model mimicking access to the maxillary sinus cavity for sinus floor augmentation.

Materials and methods: On the nasal bone of 16 adult New Zealand white rabbits, two types of osteotomy window defects of nasal cavities were marked to critical size with a Trephine drill (ø 5 mm) and then prepared with either a conventional rotary bur or piezo-surgery (PIEZOSURGERY® Insert OT5 of PIEZOSURGERY® 3 unit, Mectron s.p.a., Genova, Italy). The defects were covered with a resorbable membrane (Bio-Gide®, Geistlich Pharma AG, Wohusen LU, Switzerland). Four animals were sacrificed at one, two, three and five weeks after surgical procedure, respectively. Histological and morphometric evaluations were performed to assess the volumetric density of various tissue components: the blood clot (BC), vascularized structures (VS), provisional matrix (PM), osteoid, mineralized bone (MB), bone debris (BD), residual tissue, old bone (OB).

Results: at the 1 week, more BC detected after piezo- surgical preparation. However, the difference did not reach statistical significance. A tendency of higher proportions of osteoid in the conventional bur defects was noted, but not statistically significant. Significantly more BD was found in the conventionally compared to the piezo-surgically prepared defects. At two weeks, new bone formation was noted, and the process of modeling of the newly formed bone had started. More MB was detected in the defect prepared by piezo-surgery than by conventional bur, but without any statistically significant difference. In the marginal areas of defect, slightly more osteoblasts (Obl) were present in piezo-surgically prepared defect than in conventional prepared defect, although there is no significant difference. At 3 week, a newly formed hard tissue bridge mainly composed of woven bone was seen. A high volumetric density of mineralized bone (MB) presented in all the specimens, At the 5 week, the defects were completely filled with newly formed bone.

Conclusion: the defect prepared by piezo-surgery showed a significantly decreased proportion of bone debris at one week compared to conventional rotary bur defect. Increased volumetric densities of mineralized bone were observed in the piezo-surgical compared to the conventional bur defect after two weeks, although not statistically significant. Irrespective of the preparation modality of the defect performed, the defect was almost filled with newly formed bone at three weeks. At five weeks, complete regeneration of the calvaria defects was achieved.