Comparison of the thermal changes of conventional and ultrasonic bone cutters

Hard tissue osteotomies are one of the most commonly used procedure in oral and maxillofacial surgery. Conventional and ultrasonic osteotomy methods are frequently used for this procedure. The main disadvantage of bone burs and bone saws which are conventional methods attached to rotary tools, is their damage to close anatomical structures. For this reason, ultrasonic osteotomy systems that work with selective vibration systems and feature selective cutting between hard and soft tissues, have started to be preferred. The development of ultrasonic systems provides a safe opportunity for operations around nerves, blood vessels, and sensitive anatomical structures in the dentomaxillofacial region which require much attention. Currently, the commonly used ultrasonic osteotomy devices are piezosurgery and ultrasonic bone scalpel. Although it is safer and causes fewer iatrogenic errors, there are some concerns about increased osteotomy time, osteotomy speed and heat build-up. The aim of this study is to compare the thermal changes caused by conventional (bone saws and bone burs) and ultrasonic osteotomy systems (piezosurgery and ultrasonic bone scalpel) during bone osteotomy of the same duration and length under two different irrigation variables. This study was approved by Başkent University Medical and Health Sciences Research Board on 09/07/2020 (Project number: D-KA20 / 11) and supported by Başkent University Research Fund. Fresh bovine ribs were used as in vitro study materials, and two K-type thermocouple cables and universal input microcontroller design data-loggers were used as temperature sensors for the measurement of thermal difference. Slots where the thermocouples will be placed, were opened on the bone blocks under the saline irrigation. The location of the slots were opened 1 mm away from the osteotomy line. One is 1.5 mm (at the cortical bone level) and the other one is 7 mm (at the cancellous bone level) deep. Thermocouple sensors were placed in the prepared slots. Osteotomy procedures were performed with four different instrument groups. In each group, osteotomy was 1 cm / min, bicortical and made under two different irrigation variables (20 ml / min and 80 ml / min saline). The results of temperature changes were transferred to the computer via sensors. The statistical results of the study were examined by One-Way ANOVA whether there was a significant difference between the means of cortical and cancellous measurements in the groups of 20 ml / min saline irrigation and 80 ml / min saline irrigation. After One-Way ANOVA, TUKEY test was used to determine which group the difference originated from. Analyzes were made with SPSS 20.0 software at 95% confidence level. Temperature changes during osteotomy were highest in ultrasonic bone scalpel, piezoelectric, conventional bone bur and bone saw groups, respectively. Although there are many studies showing that ultrasonic osteotomy instruments are safer for the surrounding soft tissues and are more beneficial in the post-operative period, the highest temperature increase was seen in this groups. Keywords: piezoelectric surgery, ultrasonic bone scalpel, conventional bone burs, conventional bone saw, thermocouple