The interactive effect of bone density and drill type on heat generated during drilling of dental implant osteotomy: a single versus sequential drills in vitro experiment

Drilling an implant osteotomy involves bone removal using specific drill designs, under irrigation, and at controlled speeds and forces. The interaction among these parameters generates heat that may impair bone viability, potentially resulting in fibrous encapsulation and osseointegration failure. This study aimed to evaluate the amount of heat produced during osteotomy preparation using a single-drill protocol compared with conventional sequential drilling in artificial bone blocks of varying densities. A total of 240 osteotomies were prepared in polyurethane blocks simulating D1–D4 bone types. For each density, 30 osteotomies were created using a single drill (4 mm × 15 mm) and 30 using conventional sequential drills, totalling 120 per protocol. A K-type thermocouple was positioned 1 mm from the final osteotomy wall to record bone temperature immediately after drilling. Data were analysed using a two-way ANOVA to assess the effects of bone density and drill type on temperature rise, with normality and homogeneity verified using the Shapiro–Wilk and Levene’s tests. In D1 and D2 bone types, single drills produced lower mean temperatures (25.2 ± 0.65 °C; 22.9 ± 0.56 °C) than conventional drills (26.3 ± 0.85 °C; 24.2 ± 0.44 °C). Conversely, in D3 and D4 bone types, single drills generated slightly higher temperatures (24.7 ± 0.47 °C; 24.5 ± 0.72 °C) than conventional drilling (23.5 ± 0.65 °C; 23.4 ± 0.79 °C). ANOVA revealed a significant effect of bone density (F = 129.62, p < 0.001) and a density–drill interaction (F = 69.03, p < 0.001), but no main effect of drill type (p = 0.776). Within the limitations of this study, single-drill osteotomy generated less heat in dense bone (D1–D2) but more in softer bone (D3–D4), suggesting that bone density modulates the thermal response during implant site preparation.