## 4 Discussions  
One factor that should be considered for implant stability is the influence of the interaction between the implant macrogeometry and the prepared bone bed [4; 28]. When analyzing these two factors, it is suggested that a high insertion torque is desirable to improve implant stability during the osseointegration process, and to reduce implant micromovement [36]. In the present study, whether osseodensification allows for the use of wider implant beds to create healing chambers without jeopardizing implant stability was investigated. Figure 4: Flowchart (CONSORT) illustrating the implant placements of the clinical trial. Figure 5: IT (Ncm) and ISQ values of osseodensification + healing chamber and standard undersized drilling groups. The most widely accepted parameters to assess clinical implant stability are IT and ISQ [37, 38]. While IT measures the frictional resistance of implant rotation into the bone, ISQ measures the implant stability during the healing process using the resonant frequency [38]. There is some debate regarding this relationship, but IT and ISQ can be considered to be independent methods to measure implant stability [39] and, therefore, no correlation analysis was performed. Higher IT and ISQ values are considered to be strong indicators for low implant micromotion, high stability for immediate loading, and osseointegration [40, 41, 42]. It was possible to identify higher IT values when using osseodensification instrumentation protocol. Bone is a dynamic tissue that responds to stimuli--the surgical procedure and the interaction between the macrogeometry of the implant and its associated osteotomy drilling dimensions, in this case. Several studies have suggested that high values of IT do not necessarily indicate a higher degree of secondary stability and stabilized healing process [41, 43]. A previous study demonstrated that a protocol undersized by no more than 10% is sufficient to improve the primary stability of the implant in regions of poor bone density [3], composed of weak bone trabeculae surrounded by a thin layer of lamellar bone [26]. However, in many clinical scenarios (as is the case in this study), it is necessary to use a final 2.8 mm standard drill to place a 3.5 mm implant in order to optimize implant stability. This represents a downsizing method to achieve higher IT and ISQ values to allow immediate provisional restoration without loading [27, 28, 41]. For comparison, in G1, wider osteotomies were established to create a healing chamber at the implant and bone interface, and this still produced higher IT values. Although ISQ values were similar in both groups, the osseodensification instrumentation prevented the need for undersizing the osteotomies and provided the requisite microgap for bone-chamber healing without reducing implant stability. Both in vitro and in vivo studies have demonstrated up to a three-fold increase in primary stability when leveraging osseodensification [17, 21, 22, 44, 45, 46] In the present study, osseodensification allowed the use of a wider diameter (3.8 mm) implant bed to place a 3.5 mm diameter implant with adequate stability. In addition, a previous in vitro histological study [46] reported that osseodensification does not reduce primary stability during bone healing due to the compacted autograft that promotes osteoblast activity--early osteoid tissue formation with osteons present at the implant bed, which act as nucleating surfaces for the osteoblasts around the implant [47]. Further, the compaction autografting produced by osseodensification would produce higher BIC values [47]. However, in the present study, both groups exhibited similar stability after 6 months of healing. Other authors [12, 40, 47, 48, 49] have noted that implant stability also depends on the geometry of the threads. Larger implant threads with higher pitches contact more bone trabeculae and have improved bone-chip compaction.