Micromorphometrical analysis of conventional osteotomy techniques and ultrasonic osteotomy at the rabbit skull.

OBJECTIVES: The ultrasonic osteotome, which was recently introduced, is an alternative to conventional methods of osteotomy. The aim of the present study was to establish the differences between three osteotomy techniques and to perform a quantitative roughness analysis of the osteotomized bone surfaces. MATERIALS AND METHODS: Fresh bony samples of standardized size were taken from the rabbit skull. The techniques used were as follows: reciprocate micro-saw, Lindemann bur, ultrasonic osteotome with the two insert tips OT6 (rough) and OT7 (fine). The prepared surfaces were examined by light microscopy, environmental surface electron microscopy (ESEM) and by confocal laser scanning microscopy (CLSM). RESULTS: It was difficult to distinguish between cortical and cancellous bone after using the conventional osteotomy technique. The ultrasonic technique preserved the original structure of the bone. The values observed for superficial roughness were as follows: 3.97 microm (micro-saw), 5.7 microm (Lindemann bur), 2.48 microm (OT7) and 3 microm (OT6). There were statistical differences between the values of the bur and insert tip OT6 (P=0.015) as well as between the bur and insert tip OT7 (P=0.003). CONCLUSIONS: In the present study micromorphological differences after using various osteotomy techniques could be clearly identified.

[Light microscopic examination of rabbit skulls following conventional and Piezosurgery osteotomy]. / Auflichtmikroskopische Untersuchungen an der Kaninchenkalotte nach ultraschallgestützter und konventioneller Osteotomie.

INTRODUCTION: The novel ultrasonic osteotomy technique (Piezosurgery) is an alternative to conventional osteotomy devices. The aim of the present study was to carry out morphological comparison of the bone surface using conventional osteotomy techniques in comparison to the rather new ultrasonic osteotomy technique by means of a reflected-light microscopic examination. MATERIALS AND METHODS: Following the sacrifice of 12 rabbits, 24 standardized bone samples were removed from the skull. The osteotomy devices used were a rotating instrument (Lindemann bur), an oscillating micro-saw, and an ultrasonic osteotomy device (Piezosurgery) with insert tips OT6 and OT7. The times needed for osteotomy were measured. The bone surfaces were examined using a reflected-light microscope with a magnification of 40x and 100x. RESULTS: Osteotomy with Piezosurgery is significantly more time consuming than osteotomy with conventional methods (p<0.05). Following osteotomy with the ultrasonic device, the reflected-light microscopic examinations of the unmodified bone samples revealed typical bone structure of the calvaria, including compacta externa, diploe and compacta interna. On the contrary, following osteotomy with the conventional devices, the diploe structure presented distinct modifications. The cancellous spaces were filled with bone debris, and the cancellous structure was demolished. The samples prepared by the micro-saw technique showed a superficially condensed and grooved surface. CONCLUSION: In the present study, well-defined differences were observed following osteotomy with conventional devices and osteotomy with the ultrasonic device. The integrity of the bony structure observed after the ultrasonic technique could benefit the bone healing process. Further studies dealing with the bone healing process after using different osteotomy techniques are recommended.