## 3 Results  
The descriptive statistics of the measured thermal changes are given in Table 1.  
Almost all pairwise comparisons indicated significant difference at \(p<0.05\); the exceptions are given in Table 2.  
In three groups, the measured temperature increment was >5 \({}^{\circ}\)C (no irrigation at 600, 900, and 1200 rpm). In one group, the temperature increment was \(\geq\)10 \({}^{\circ}\)C (no irrigation at 900 and 1200 rpm). Thus, extreme increments were observed only in the unirrigated groups. Irrigation invariably made a significant difference within groups defined by the same drilling speed. The use of a 20 \({}^{\circ}\)C irrigation fluid resulted in a lower temperature increment, which remained in the safe zone throughout the use of every drilling speed (200, 600, 900, and 1200 rpm). In all of the groups with 10 \({}^{\circ}\)C external irrigation, the measured temperature changes were negative in comparison to the baseline cortical intraosseous \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \begin{tabular}{c} **Grouping** \\ **Number** \\ \end{tabular} & \begin{tabular}{c} **Drilling** \\ **Speed (rpm)** \\ \end{tabular} & \begin{tabular}{c} **Temperature** \\ **of Irrigation** \\ **Fluid (\({}^{\circ}\)C)** \\ \end{tabular} & \begin{tabular}{c} **Number of** \\ **Drillings** \\ \end{tabular} & \begin{tabular}{c} **Mean (SD)** \\ **Temperature** \\ **Rise (\({}^{\circ}\)C)** \\ \end{tabular} & \begin{tabular}{c} **Maximum** \\ **Temperature** \\ **Rise (\({}^{\circ}\)C)** \\ \end{tabular} & \
\begin{tabular}{c} **Minimum** \\ **Temperature** \\ **Rise (\({}^{\circ}\)C)** \\ \end{tabular} &
\begin{tabular}{c} **Median** \\ **Temperature** \\ **Value (\({}^{\circ}\)C)** \\ \end{tabular} \\ \hline
1 & 200 & 10 & 40 & \(-\)2.45 (0.57) & \(-\)1.30 & \(-\)3.50 & \(-\)2.50 \\
2 & 200 & 20 & 40 & 0.05 (0.07) & 0.20 & 0.00 & 0.00 \\
3 & 200 & no irrigation & 40 & 2.22 (0.71) & 3.80 & 1.20 & 2.10 \\
4 & 600 & 10 & 40 & \(-\)1.76 (0.35) & \(-\)1.00 & \(-\)2.80 & \(-\)1.80 \\
5 & 600 & 20 & 40 & 1.02 (0.33) & 1.30 & 0.00 & 1.20 \\
6 & 600 & no irrigation & 40 & 3.75 (0.97) & 6.10 & 2.00 & 3.75 \\
7 & 900 & 10 & 40 & \(-\)1.02 (0.38) & 0.20 & \(-\)1.30 & \(-\)1.15 \\
8 & 900 & 20 & 40 & 1.48 (0.56) & 2.60 & 0.50 & 1.30 \\
9 & 900 & no irrigation & 40 & 5.92 (1.14) & 9.50 & 4.40 & 5.90 \\
10 & 1200 & 10 & 40 & \(-\)0.18 (0.23) & 1.30 & 0.00 & 0.10 \\
11 & 1200 & 20 & 40 & 1.86 (0.65) & 3.40 & 1.20 & 1.70 \\
12 & 1200 & no irrigation & 40 & 7.76 (1.59) & 11.50 & 4.70 & 7.45 \\ \hline \hline \end{tabular} SD: Standard deviation.  
\end{table} 
Table 1: Mean temperature rises, maximum and minimum of temperature rises, groups divided by different drilling speeds, and temperature of the irrigation fluid. Figure 4: The study setting, including the bench drill, and the irrigation system (provided by the surgical unit). temperature, despite the drilling procedure. This might be the result of the cooling effect of the irrigation fluid being more pronounced than the heat-producing effect of the drilling. The comparison of the different temperature irrigation fluids (10 and 20 \({}^{\circ}\)C) in combination with the same drilling speed (200, 600, 900, or 1200 rpm) resulted in a statistically significant difference between the two different temperatures, whereas the use of irrigation fluid at a controlled room temperature of 20 \({}^{\circ}\)C showed significantly higher temperature changes. A graphical summary of the results is given in Figure 5.