## 4 Discussion  
### Influence of the Milling Cutter Drill  
The results obtained in this study demonstrate that the use of the milling cutter drill led to a statistically significant difference in angular deviation, which was lower in the group where the drill was used.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \multirow{2}{*}{**Deviation**} & \multicolumn{4}{c}{**Implant, Median (IQR)**} & \multicolumn{2}{c}{**Kruskal–Wallis**} \\ \cline{2-6}  & **BL** & **BLT** & **BLX** & **H** & \(p\)**-Value** \\ \hline Angular (\({}^{\circ}\)) & 3.25 (2.15) & 3.20 (2.20) & 2.80 (2.45) & 1.020 & 0.601 \\ \hline Neck of the & & & & & \\ implant (mm) & & & & & \\
3D & 0.45 (0.50) & 0.47 (0.78) & 0.91 (0.54) & 15.860 & **<0.001** \\ MD & 0.09 (0.21) & 0.11 (0.36) & 0.08 (0.08) & 3.034 & 0.219 \\ BL & 0.10 (0.22) & 0.20 (0.56) & 0.25 (0.66) & 7.818 & **0.020** \\ AC & 0.45 (0.47) & 0.56 (0.77) & 0.70 (0.79) & 6.903 & **0.032** \\ \hline Apex of the & & & & & \\ implant (mm) & & & & & \\
3D & 0.84 (0.42) & 1.05 (0.66) & 0.90 (0.67) & 4.352 & 0.113 \\ MD & 0.25 (0.19) & 0.25 (0.44) & 0.19 (0.21) & 3.500 & 0.174 \\ BL & 0.43 (0.40) & 0.49 (1.00) & 0.37 (0.38) & 6.201 & **0.045** \\ AC & 0.53 (0.42) & 0.72 (0.95) & 0.68 (0.83) & 4.905 & 0.086 \\ \hline \end{tabular}  
* IQR: interquartile range; 3D: three-dimensional; MD: meso-distal; BL: bucco-lingual; AC: apico-coronal; BL: bone level implant; BLT: bone level tapered implant; BL: bone level X implant.  
\end{table}
Table 4: Influence of implant type on implant deviation parameters.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \multirow{2}{*}{**Deviation**} & \multicolumn{4}{c}{**Type of Bone, Median (IQR)**} & \multicolumn{2}{c}{**Kruskal–Wallis**} \\ \cline{2-6}  & **D1** & **D2** & **D3** & **D4** & **H** & \(p\)**-Value** \\ \hline Angular (\({}^{\circ}\)) & 2.90 (2.30) & 2.50 (1.80) & 3.55 (2.30) & 3.60 (1.70) & 6.747 & 0.080 \\ \hline Neck of the & & & & & & \\ implant (mm) & & & & & & \\
3D & 0.99 (0.45) & 0.61 (0.62) & 0.40 (0.53) & 0.55 (0.45) & 9.140 & **0.027** \\ MD & 0.12 (0.30) & 0.08 (0.39) & 0.08 (0.05) & 0.10 (0.10) & 8.559 & **0.036** \\ BL & 0.58 (0.40) & 0.16 (0.37) & 0.06 (0.06) & 0.12 (0.21) & 40.183 & **<0.001** \\ AC & 0.74 (0.69) & 0.69 (0.83) & 0.41 (0.43) & 0.51 (0.41) & 3.201 & 0.362 \\ \hline Apex of & & & & & & \\ implant (mm) & & & & & & \\
3D & 0.90 (0.54) & 0.84 (0.81) & 0.73 (0.55) & 0.95 (0.49) & 6.064 & 0.109 \\ MD & 0.25 (0.25) & 0.25 (0.25) & 0.19 (0.21) & 0.26 (0.28) & 6.649 & 0.084 \\ BL & 0.39 (0.17) & 0.38 (0.32) & 0.47 (0.41) & 0.67 (0.68) & 6.888 & 0.076 \\ AC & 0.84 (0.71) & 0.69 (0.84) & 0.46 (0.43) & 0.50 (0.36) & 13.047 & **0.005** \\ \hline \end{tabular}  
* IQR: interquartile range; 3D: three-dimensional; MD: meso-distal; BL: bucco-lingual; AC: apico-coronal; BL: bone level implant; BLT: bone level tapered implant; BL: bone level X implant.  
\end{table}
Table 3: Influence of bone density on implant deviation parameters.  
The use of the milling cutter drill in the partially guided protocol demonstrated a measurable effect, confirming its influence on the angular deviation parameter. The differences found in this study support the hypothesis that, even in guided surgery, bone density and implant macrogeometry can affect the positioning of the implant in relation to the planned trajectory [16; 18].  
The milling cutter drill facilitates implant placement by enabling cortical flattening, which may explain the greater predictability of the final position [17]. By reducing surface irregularities at the alveolar crest, the drill likely enhances drill stability during initial osteotomy steps, decreasing angular deviation--a parameter particularly relevant in anterior and multi-unit prosthetic planning. However, it did not significantly reduce the other deviation values (3D and linear), although the angular improvement alone may already be clinically relevant [9; 10; 11; 22; 12].