Proposal for an Ultrasonic Tool to Monitor the Osseointegration of Dental Implants

Abstract

The longevity of dental implants depends on osseointegration, which providesload-bearing capacity without putting the prosthesis at risk from micromotions at theimplant-bone interface. This research involved an analysis of the viability of an ultrasonicevaluation tool to quantify osseointegration. Ultrasonic transmission is directly dependenton the difference between the acoustic impedance of materials in intimate contact witheach other. The closer their acoustic impedances the more intense their transmission.Therefore, an analysis of the ultrasonic echoes would presumably allow for a quantitativeevaluation of the bone tissue that has grown into the pores of the implant. In addition, theliterature reports that bone fracture healing can be accelerated by the application of acontrolled low-amplitude mechanical stimulus on the site of the lesion. In fact, acousticpressure waves of low-intensity pulsed ultrasound are reportedly a secure technique forpromoting mechanical stimulus without impairing the healing process. Many experimentaland clinical trials have confirmed that daily transcutaneous ultrasound applications on theinjured site are beneficial to the enhancement of fractured bone. This proposal aims tobring together the characteristics of ultrasound propagation and the positive effect ofultrasound on bone growth into a single tool that quantitatively monitors the evolution ofthe osseointegration process. The viability of a device with these features was investigatedthrough simulations and experimentally. The initial simulations were conducted to explorethe influence of waveguide shapes on the tool’s sensitivity to changes in the implantsupporting media. The waveguides were designed in two parts, one consisting of a screw-shaped part to attach to the implant and the other a conical or step-shaped part to which the ultrasonic source was fixed in the first simulations. The step-shaped waveguide proved to be the more sensitive; intermediate stages of the osseointegration process were simulated and experiments were conducted with the step-shaped aluminum waveguide attached to a cylindrical aluminum nut embedded at different depths, so that the results obtained were only due to lateral attachment of the parts. These devices indicated that the transmission of ultrasound through the lateral surface of the implant by dilatational waves could render this tool suitable for monitoring the osseointegration of dental implants

Ultrasonic Evaluation of Dental Implant Biomechanical Stability: An In Vitro Study

“…Due to the precision error of the concentricity of the successive drillings (around 100 mm), this gap ensures that bone surrounding the implant is maintained distant from the implant surface. Varying the depth of the diameter change allows considering the effect of the cortical layer, which would not be possible if only the anchorage depth was varied, as done in (de Almeida et al 2007). Prototype cylinder shaped implants (diameter D 5 4 mm, length h 5 7 mm) made of TiAl6V4-ELI (which is the reference titanium alloy for dentistry implants) were then placed into the cavities.…”

“…The principle of the measurement relies on the dependence of ultrasonic propagation within the implant on its boundary conditions, which are precisely related to the bone-implant interface biomechanical properties. However, the experiments performed in de Almeida et al (2007) were realized with an aluminium piece inserted in a metallic medium and the feasibility of such approach for implants inserted within bone tissue remains unknown.…”

“…The use of quantitative ultrasound (QUS) as an alternative method to assess the implant biomechanical stability has been suggested (de Almeida et al 2007). The approach described in de Almeida et al (2007) nicely consists in using the implant as a threaded aluminium piece excited by an ultrasonic transducer in echographic mode.…”

“…The approach described in de Almeida et al (2007) nicely consists in using the implant as a threaded aluminium piece excited by an ultrasonic transducer in echographic mode. The principle of the measurement relies on the dependence of ultrasonic propagation within the implant on its boundary conditions, which are precisely related to the bone-implant interface biomechanical properties.…”

Modeling the electromechanical impedance technique for the assessment of dental implant stability

“…As the quest for a perfect biomechanical method is not limited to the improvements of the two commercial systems, some authors have proposed alternative approaches based on quantitative ultrasounds (De Almeida et al, 2007;Mathieu et al, 2011aMathieu et al, , 2011bVayron et al, 2015) or the electromechanical impedance (EMI) (Boemio et al, 2011;La Malfa Ribolla et al, 2015;Tabrizi et al, 2012). The latter technique consists of bonding one wafer-type lead zirconate titanate transducer (PZT) to the implant or the abutment to be monitored and of measuring the electrical characteristics of the transducer which are related to the mechanical characteristic of the host structure.…”