Measuring on Abutment…

_{López-Jarana, Paula et al. “Is It Possible to Monitor Implant Stability on a Prosthetic Abutment? An In Vitro Resonance Frequency Analysis.” International journal of environmental research and public health vol. 17,11 4073. 8 Jun. 2020, doi:10.3390/ijerph17114073}

Is It Possible to Monitor Implant Stability on a Prosthetic Abutment?

Implant stability is a key factor for successful osseointegration of dental implants. It is important to maintain a suitable level of stability over time for long-term success. Clinicians can enhance their daily practice decisions by measuring implant stability at different stages.

RFA is a reliable and reproducible method to evaluate implant stability objectively at any point of treatment or follow-up.

Several factors can affect the ISQ values, such as the actual implant length, the distance between the transducer and the marginal bone (ISQ value decreases as the distance increases), the bone quality, the torque applied to the transducer, the presence of soft tissue between the implant and the transducer, and the amount of bone contact with the implant.

Removing the prosthetic abutments to measure implant stability during the healing period poses the risk of pulling out the implant if the connection force between the abutment and the implant is too strong. Knowing that repeated disconnection / reconnection of the abutments could cause more marginal bone loss, the “one-abutment–one-time” protocol was proposed as a less invasive prosthetic approach. To implement the one-abutment–one-time concept, transducers that can be screwed onto the abutments were designed, unlike the previous transducers that had to be screwed directly onto the implant. These new transducers are intended to prevent the disconnection / reconnection of abutments to measure the implant stability and to simplify the ISQs recording (as there is no need to take off the abutment).

As the transducer is positioned more coronally (on top of the abutment), the stability measurement is easier and more convenient for the clinician. Another benefit of this method is that, in cases of low stability, there is no application of counterclockwise forces (implants with insufficient stability are not exposed to such forces).

However, screwing the transducer onto the abutment (and not directly onto the implant) could alter the ISQ values, as the transducer is further from the bone than when it is screwed onto the implant. These changes, when performing RFA, could result in a higher vibration of the bone—implant interface and, therefore, lower the ISQ values. Therefore, it is essential to compare the ISQ measurements when using the transducers screwed directly onto the implant or onto the abutments.

The aim of this publication was to compare the ISQ values obtained by the Penguin RFA when screwing the MulTipeg onto the implant or abutments with different heights and angles.

Penguin RFA is known to show excellent repeatability and reproducibility, so it was appropriate to monitor the stability of implants.

In previous studies by Diaz-Castro et al. in 2019, Penguin RFA showed ICC values of 0.933 and 0.944 for Transducers 1 and 2, respectively. The reproducibility was 0.906.

The implants and MulTipegs used in this study were VEGA® with a 3.5 mm diameter (MulTipeg 57) and VEGA® with a 4 mm diameter (MulTipeg 26). Permanent® abutments were screwed with metallic hand-screwdrivers with an IT of 5–10 N/cm2.

The MulTipeg used for the Permanent® abutment was Reference 72.

To compare the values of implant stability over time more accurately, Lages et al. suggest using a consistent method of measuring ISQ values (either on platforms or abutments), since they vary based on the height and angle of the abutment or the implant itself.

This study found that ISQ values are higher when straight abutments with a 1 mm height are used for measurements. This could be because the abutments go through the mucosa, having the implant platform further from the oscillating force. This also means that the transducer would need a longer distance from the top to the bone level to measure the implant directly. This could affect how the signals are transmitted to the bone in the RFA.

The current study suggests that ISQ values can be measured directly on a permanent abutment with heights of 1, 2 or 3 mm in clinical practice. This would prevent the need to remove prosthetic abutments, which could cause the implant to come out if the connection between the abutment and the implant is too strong. One limitation, besides being an in vitro study, is that the abutment design could change the average values obtained, as different brands could have different designs.