Take-home messages

  • The Integral of the torque-depth curve recorded during implant insertion is a validated primary stability measure.
  • The Integral, in fact, not only correlates with IT and ISQ, the two other well-known primary stability measures, but also correlates with the BIC, the bone-to-implant contact are.
  • Furthermore, it has recently been demonstrated, directly and independently, that the Integral is also a measure of the micro-movements to which the implant is subject once it has been fully seated.

The Integral of the torque-depth curve measured through TMM3 during implant insertion has been studied through two investigations carried out in collaboration with the Vita e Salute University of Milan and the University of Chieti. The results were published in 2015 in two of the most well-known journals in implantology: the Clinical Implant Dentistry and Related Research and the Journal of Dental Sciences.

The researchers investigated whether the Integral of the torque-depth curve, which had already been shown to correlate significantly with the traditional measures of primary stability, IT and ISQ, but much more sensitively to variations in bone density, was also correlated with the bone-to-implant contact area (BIC) immediately after insertion.

The study conducted at the San Raffaele Hospital in Milan is particularly relevant as it was carried out on patients: mini-implants were inserted, and after 15 minutes, they were removed together with a portion of bone tissue around them for subsequent histomorphometric analysis, and to measure the immediate post-insertion BIC.

The study conducted at the University of Chieti used bovine ribs as an experimental system: an excellent model commonly used to simulate the alveolar process. The experiment was conducted much in the same way: after placing the implants and measuring the Integral at each placement, researchers performed histomorphometric assessments, specific to hard tissue analysis, to measure the BIC.

In both cases, the Integral-BIC correlation was found to be highly significant: the importance of this result is that, while previous studies had validated the Integral in terms of interchangeability with IT and ISQ, i.e., with other measures of primary stability, these investigations directly demonstrated that the Integral is a true measure of how much the implant comes into contact with the bone: they show that the relationship between the Integral and primary stability is direct, and not mediated.

Further, independent confirmation of the validity of the Integral as a measure of primary implant stability was recently obtained by Prof. De Marzi’s group at the Department of Industrial Engineering at the University of Padua: the researchers directly measured the magnitude of lateral micromovements in two different types of implants after placing them in polyurethane blocks and calculating, for each placement, the integral of the torque-depth curve—revealing a highly significant inverse correlation between the integral and micromovements; the same result was obtained both by varying the implant geometry and by altering the conditions for preparing the implant site.

References

Capparé P, Vinci R, Di Stefano DA, Traini T, Pantaleo G, Gherlone EF, Gastaldi G. Correlation between Initial BIC and the Insertion Torque/Depth Integral Recorded with an Instantaneous Torque-Measuring Implant Motor: An in vivo Study. Clin Implant Dent Relat Res. 2015 Oct;17 Suppl 2:e613-20. doi: 10.1111/cid.12294. 
Link to the article
IF: 3,900 (2025)

Iezzi G, Filippone A, Di Stefano DA, Arosio P, Piattelli A, Scarano A, Perrotti V. A site-specific intraoperative assessment of bone-to-implant contact during implant insertion. A study on bovine ribs using a computerized implant motor. Journal of Dental Sciences. 2015 Mar; 10(1):21-7.
Link to the article 
IF: 3,600 (2025)

De Marzi A, Arosio P, Arosio F, Franchin G, Di Stefano DA. The Insertion Torque-Depth Curve Integral and Implant Micromotion: A Study on Polyurethane Foam Blocks. Int J Oral Maxillofac Implants. 2026 Jun 10;41(Suppl 1):s101-s111. doi: 10.11607/jomi.11429.
IF: 2,000 (2025)

 


The experimental protocol involves implant insertion and then measuring the BIC through sections that include both the implant and the bone tissue; in the image, four implants are placed in bovine ribs having different bone densities. The correlation between the Integral and t he BIC is measured through specific statistical tests: on the right, as the Integral increases, the BIC proportionally increases, demonstrating that the Integral may be understood as a direct BIC measure. 

What is the importance for clinical research?

The bone-to-implant contact are (BIC) is a parameter not accessible to the clinician when operating on a patient and can only be inferred indirectly from classic stability measures (IT and ISQ): in both cases, however, the two parameters do not allow distinguishing situations where the implant is stabilized by the entire bone thickness or only by specific portions (e.g., the coronal or apical cortical layer in contact with the implant). The Integral is instead the sum of all the interactions that the implant had with the bone tissue (whose magnitude is also shown in the graph produced by TMM3): the Integral is, thus, a more accurate estimator of the extent of contact between bone and implant. The researcher thus may exploit a parameter, the Integral, that measures not only the primary stability of the implant but also the BIC, without the need for direct histomorphometric analysis. Furthermore, researchers now know that the Integral specifically and directly measures the extent of the implant’s micromovement upon completion of its placement, not only confirming its validity as an estimator of primary stability, but also serving as a direct measurement tool for conducting future studies aimed at investigating the extent to which the implant’s macro- and micromorphological parameters may impact the extent of its micromovements upon completion of placement.

What is the impact on everyday operability?

  • Measuring the Integral at the end of insertion, and assessing the torque-depth graph provided by TMM3, provides the surgeon with an additional parameter, more informative than the IT, to assess the actual stability achieved by the implant.
  • This can lead to enhanced awareness regarding the loading protocol to be applied: immediate, early, or delayed.
  • Furthermore, measuring the Integral objectively validates the site preparation protocol: the surgeon immediately, and intraoperatively, has confirmation of the adequacy of the preparation protocol adopted, using a parameter more sensitive to density variations than IT or ISQ.

In support of IDI Evolution devices

TMM3 becomes a reliable companion for the oral surgeon: during implant insertion, a glance at the graph produced by the motor, together with the verification of the obtained Integral value, helps the implantologist confirm the choice of the implant site preparation protocol and, above all, that of the load to be applied: immediate, early, or delayed.

The stability measurement obtained with TMM3 is not indirect; rather, it is a direct measurement of the bone-implant contact area (BIC) and of the implant’s micromovements themselves, in relation to all the interactions the implant has had with the bone during its placement.

Other Publications

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We have paved the way to provide objective protocols for undersizing the cortical layer, making the clinical procedure reproducible, and the outcome predictable in terms of MBL

The relationship between the extent of cortical undersizing, the primary stability it allows to achieve, the early and late marginal bone resorption it may induce has still not been clarified: studies on this matter are contradictory and inconclusive.
However, IDI Evolution systems are the only ones capable of site-specific discrimination and operator-independent assessment of different combinations of cortical thickness and cancellous density, providing a measure of implant primary stability, the Torque-Depth Integral, which also evaluates the mechanical stress exerted on the cortical thickness.

Read moreabout We have paved the way to provide objective protocols for undersizing the cortical layer, making the clinical procedure reproducible, and the outcome predictable in terms of MBL

We have demonstrated that the IDI bone density diagnosis system can distinguish between different cortical-trabecular combinations, paving the way for a new objective bone classification

The research carried out by IDI Evolution shows that TMM3 measures even bone quality, that is the combination of a given cortical layer thickness and a given trabecular density.

Read moreabout We have demonstrated that the IDI bone density diagnosis system can distinguish between different cortical-trabecular combinations, paving the way for a new objective bone classification

We have defined an objective method for rationally choosing both the protocol for preparing the implant site and the shape and dimensions of the implant to be used

The Integral of the torque-depth curve, measured by TMM3 during implant insertions, varies predictably in relation to how underprepared the implant tunnel is.
The variation of the Integral is also predictable when altering the implant geometry, both in terms of shape (conical, cylindrical, etc.) and dimensions (diameter/length).
The mathematical algorithms describing these variations are also influenced by bone density.

Read moreabout We have defined an objective method for rationally choosing both the protocol for preparing the implant site and the shape and dimensions of the implant to be used