Comparison between the influence of implant diameter and implant length on the primary stability

INTRODUCTION The primary stability is a factor for successful osseointegration of dental implants. It is believed that factors that can increase the contact area between the implant and the bone, such as the implant shape, length, and diameter, can also increase the primary stability. AIM  The aim of this study was to determine whether the increase of implant length or the increase of implant diameter would contribute more to the enhancement of primary stability. MATERIALS AND METHODS The implant primary stability of 60 implants distributed in 6 groups, according their diameter, length and surface topography was evaluated using three methods: assessment of mean insertion torque, periotest values, and resonance frequency analysis. RESULTS AND DISCUSSION The results demonstrated that the primary stability achieved by increasing the diameter of the implants by 0.7 mm was comparable to that obtained by increasing their length by 2 mm at a smaller diameter (4.1 mm). When the difference in the diameter increased more (from 0.7 mm to 1.5 mm, when comparing the 3.3 mm/10 mm and 4.8 mm/8 mm implants), the increase of the length of the smaller diameter implants did not result in primary stability values comparable to those obtained during the insertion of  wider and shorter implants. CONCLUSION Considering our results as well as the literature data, we can conclude that the increase of the implant diameter affects more the improving of the primary stability than the increase of the implant length. However, it should be taken into account that this refers to a specific diameter change of 1.5 mm and length change of 2 mm. More studies, including implants with a greater difference in the length and a different diameter to length ratio, are needed to confirm or reject this relation.