Effect of Implant Design on Initial Stability of Tapered Implants

Abstract

Implant design is one of the parameters for achieving successful primary stability. This study aims to examine the effect of a self-tapping blades implant design on initial stability in tapered implants. Polyurethane blocks of different densities were used to simulate different bone densities. The two different implant designs included one with self-tapping blades and one without self-tapping blades. Implants were placed at 3 different depths: apical third, middle third, and fully inserted at 3 different densities of polyurethane blocks. A resonance frequency (RF) analyzer was then used to measure stability of the implants. Repeated-measures analysis of variance was used to examine the effect of implant design, insertion depth, and block density on RF. Analysis of covariance was used to examine the strength of association between RF and the aforementioned factors. In both medium-density (P = .017) and high-density (P = .002) blocks, fully inserted non-self-tapping implants showed higher initial stability than self-tapping implants. No differences were noted between the 2 implant designs that were not fully inserted. The highest strength of association was with insertion depth (standardized beta [std beta] = -0.60, P = .0001), followed by block density (std beta = -0.15, P = .0002). Implant design showed a weak association (std beta = -0.07, P = .09). In conclusion, fully inserted implants without self-tapping blades have higher initial stability than implants with self-tapping blades. However, the association strength between implant design and initial stability is less relevant than other factors, such as insertion depth and block density. Thus, if bone quality and quantity are optimal, they may compensate for design inadequacy.

Surface treatment of implants: primary stability

“…Moreover, it is important to note that, depending on a material's density, it may show some similarity regarding the effects of the resonance frequency analysis when this density is similar to that of another substrate. The studies of Chong et al 9 show that resonance frequency readings prove to be similar when implants are inserted in higher density polyurethane (50 PCF, equivalent to D1 type bone) and average density polyurethane (40 PCF, similar to D2 type bone). This study also shows statistically similar results for polyurethane specimens with approximate densities of 20 and 15 PCF and Synbone, both in machined implants and surface treated implants.…”

“…Degidi et al 7 claim that a surgeon's ability to predict primary stability through subjective analysis is not always effective, mainly with low resonance frequency and insertion torque values. Therefore, more objective, systematic measurements must be encouraged, mainly in cases where an immediate loading regimen is the aim, where knowing the implant's initial stability, immediately after insertion in the bone, is of crucial importance in defining the opportune moment for the application of load 5,7,13 so as to ensure natural healing and effective bone formation, thereby enabling optimal stress distribution of functional masticatory loading 9 .…”

“…This analysis, presented as an implant stability quotient (ISQ, with a value between 0 and 100), in which a higher value indicates increased stability 2,6,13 ; is influenced by the bone adjacent to the implant and the rigidity of the bone-implant interface [2][3][4]9,13 . This statement corroborates this study's results, in which higher resonance frequency values were found in implants inserted in wood and 40 PCF Nacional ® polyurethane, the materials with the greatest rigidity amongst those chosen as bone substitutes; it also corroborates studies that show that the resonance frequency of implants is proportional to the rigidity of the surrounding material.…”

“…To achieve osseointegration, it is crucial that during surgery the implant is stabilized in the receiving bone site 6 , attaining primary stability 2,[6][7][8][9][10] . This initial fixation depends on surgical technique, implant design and on patient-related factors such as bone density 1,[10][11] .…”

“…To determine the occurrence of primary implant stability, many non-invasive techniques are used, such as tactile sensitivity based on subjective perception 1,[7][8][9] . The Periotest is an instrument that assesses tooth or implant mobility 8 , however its applicability for this purpose is poor due to its low senitivity 2,4,8 .…”