## 1 Introduction  
Recent technological developments have led to significant advances in the creation of new materials and methods, and Dentistry has not been immune to these changes [1, 2, 3]. The integration of cutting-edge tools and new techniques has become a key to modern clinical practice. Consequently, the concept of Digital Dembistry (DD) is increasing in relevance in clinical and academic contexts, reflecting its growing impact on oral healthcare [1,2].  
Digital Dentistry involves a wide range of applications in daily clinical practice, including data acquisition, patient communication, diagnosis, treatment planning, and follow-up. Advances in computer-aided design (CAD) and computer-aided manufacturing (CAM) have led to the development of high-definition 3D scanners, faster and more accurate planning software, and innovative additive and subtractive manufacturing techniques [1, 2, 3, 4]. The digital workflow typically involves image acquisition (from CBCT, intraoral scanners, and facial scanners), data processing using CAD software, and the fabrication of physical components through CAM systems such as 3D printing or milling [3, 4, 5]. Each step introduces potential sources of error, highlighting the need to evaluate their cumulative effect on clinical outcomes [3,6,7].  
In implantable, digital workflows have revolutionized treatment planning and execution. CBCT and intraoral scanning technologies allow an accurate analysis of anatomical structures and the virtual planning of prosthetically guided surgeries [3,6]. This has led to more predictable treatments with reduced clinical time and improved patient satisfaction. Digital workflow in prosthodonics has also enhanced restoration precision and reduced the need for postoperative adjustments [5,7]. Despite these benefits, challenges such as costs, learning curves, and the risk of deviations between planned and final implant positions remain [5,8, 9, 10, 11, 12].  
Computer-Assisted Implant Surgery (CAIS), particularly static CAIS (s-CAIS), allows virtual planning and the fabrication of surgical guides. These guides direct the position, angulation, and depth of implant placement, improving surgical accuracy and reducing intraoperative complications. Among s-CAIS techniques, partially guided surgery (PGS) offers an alternative between guidance and manual control, maintaining clinical flexibility [13, 14, 15].  
One specific instrument that can be used in partially guided surgery is the milling cutter drill ([PERSON](r), Institut Straumann AG, Basel, Switzerland) designed to flatten the alveolar crest and provide a more stable surface for subsequent drilling steps [16, 17, 18]. This flattening is especially relevant in irregular or sloped cortical bone, as it helps minimize drill slippage and reduce angular deviations during implant placement. Although the potential of the milling cutter drill to improve implant accuracy is acknowledged, evidence supporting its benefit remains limited and underexplored in the literature, particularly in partially guided protocols [6,19].  
Given the increasing reliance on digital technologies and the continuous evolution of surgical protocols and implant designs, further research is essential to assess the biomechanical performance, predictability, and clinical efficacy of these tools. Therefore, the main aim of this study was to evaluate the impact of the milling cutter drill on the accuracy of bone level implants placement within a partially guided surgical protocol. A secondary objective was to assess how bone density and implant macrogeometry influence implant placement accuracy. This study contributes to the growing of evidence supporting digital implantology and aims to optimize outcomes through improved surgical planning and execution.