###### Abstract  
Some evidence supports the influence of implant macro-design on primary stability. Additionally, tactile perception can be used to assess implant stability when placing the implant. This research aimed to quantify the primary and secondary stability of three implant systems with two different macro geometries (cylindrical and conical) determined based on the insertion torque and the implant stability quotient (ISQ) at the moment of implant placement as a function of implant-related factors (length, width, dental arch, and implant location in the arch), intraoperative factors (bone density determined subjectively by the clinician's tactile perception), and patient-related factors (age, gender, and bone density determined objectively based on cone beam computed tomography (CBCT). Methods: 102 implants from three implant systems with two different macro geometries (conical and cylindrical) were placed in 53 patients. The insertion torque, the ISQ at the implant placement (ISQ), and the bone quality according to the clinician's tactile sensation were recorded on the day of the surgery. After a three-month healing period, the ISQ was re-evaluated (ISQ3). Results: The cylindrical implants exhibited significantly higher insertion torque and ISQ values at the moment of the surgery and after three months compared to the conical implants. The cylindrical implants also showed significantly lower indices of tactile evaluation of bone quality during the implant placement surgery. However, no differences were demonstrated in the bone density measured objectively using CBCT. (4) Conclusions: The cylindrical implants achieved the highest values for primary stability (Newtons \(\times\) centimeter (Ncm) and ISQ) and secondary stability (ISQ after three months). The insertion torque was the variable that most influenced the ISQ on the day of the surgery. The implant location (incisors-canines, bicuspids-molars) and the implant macro geometry were the variables that most influenced the secondary stability (ISQ at three months). Keywords:dental implants; bone density; macro-design; implant stability; computerized tomography; bone quality +
Footnote †: journal: Medicalone of the areas that has received the most attention, since failure rates have been observed to decrease when insertion torque increases [9; 10] because of a reduction in implant micromotion [11]. Primary stability is obtained immediately after implant placement. It depends on bone quality, implant macro geometry (implant shape, length, and diameter), and the drilling sequence used to prepare the implant bed [12; 13; 14]. This last variable (drilling sequence) depends on the early evaluation of the bone quality, which is generally based on the operator's experience. Thus, if the surgeon categorizes the bone of the implantation site as soft, the implant bed preparation will be infra-prepared. Conversely, this preparation will have a larger diameter if the surgeon perceives the bone to be more compact. Therefore, knowing the bone quality enables the clinician to optimize the drilling sequence and select the best implant design (conical or cylindrical; self-tapping or non-self-tapping) to achieve optimal primary stability [11; 15]. Several classification systems have been established for evaluating bone density. [PERSON] and [PERSON] [16] divided bone density into four types: from the more compact type I bone to type IV, which is low-density trabecular bone surrounded by a thin layer of cortical bone. [PERSON] [17] classified bone density according to the surgeon's tactile sensation, from D1, with a hardness analogous to oak or maple wood, to D4, approximately as hard as Styrofoam [17]. Objective methods have also been developed to quantitatively assess bone density based on the Hounsfield scale (Hounsfield units, HU) [18; 19], where bone density ranges between 100 and 1900 HU, while soft tissues are close to or below 0 HU [18].