Analysis of factors determining thermal changes at osteotomy site in dental implant placement - An in-vitro study

BACKGROUND: Heat generation during osteotomy site preparation is a crucial factor that determines the success of dental implant placement. Among the factors that affect the heat generation, drilling speed, hand pressure and coolant temperature are independent variables. However, a relation between these three parameters and their optimal values required for the maximum outcome has not been studied so far. This study aims at finding out a relation between these factors in order to derive the optimum balance required, using an in vitro study. MATERIAL AND METHODS: This in vitro experiment was performed on bovine femur. A total of 72 drillings were undertaken with the aid of a physiodispenser mounted on the test apparatus. Drill diameters of 2 mm and 2.8 mm, rotated at 1500, 2000 and 2500 rpm were included for the analysis. Hand pressures included for the comparison were 1.2 kgf and 2.4 kgf. Normal saline at room temperature, and that chilled to 00C were used for external irrigation. The temperature generated during drilling was recorded by infrared thermography using a Forward-Looking Infrared (FLIR) camera. RESULTS: The highest temperature during osteotomy was observed at 2000 rpm rotational speed, 1.2 kgf operator hand pressure and saline irrigant solution at room temperature. In contrast, the lowest temperature generated was using 2500 rpm rotational speed, 2.4 kgf operator hand pressure and chilled irrigant solution. CONCLUSIONS: The results indicate that none of the three experimented parameters generated heat above the critical temperature for bone necrosis (47°C). Thus, a high drilling speed with high hand pressure and continuous irrigation with copious amounts of cooled saline may be the ideal combination for implant osteotomy site preparation. Key words:Heat generation, dental implant drills, drilling speed, drilling pressure, irrigation, infrared thermography, thermal necrosis, osteotomy preparation.