ISQ and Bone to Implant Contact (BIC)

Bone to implant contact (BIC) is the percentage of the implant surface in contact with bone on a microscopic level.

 

Young’s Modulus, Stability and Micro Motion

If the E-modulus (Young’s modulus) is high, in any material, it means that the material stiffness is high. If a tapered screw is screwed into hard wood for instance, the stability will be high due to the relatively high stiffness of the wood. Such a screw will move very little when subjected to forces (low micromotion) even if the “screw-to-bone” contact might be in the range of 50 % or lower. Even if the screw is glued in place and thus increasing the “screw-to-bone” contact to 100 %, the stability will not increase significantly since the stability was already high from the beginning. This reasoning is valid for practically all solid materials, including dense bone. For the reasons above, BIC does not have a linear correlation with implant stability. Osstell (RFA) measures the implant stability by measuring the stiffness in the interface between the implant and the bone which in turn is a measurement of the micro mobility (µm /N).

In Soft to Medium Bone

When the initial stability is low to medium, osseointegration will change the bone around the implant so that the stability and stiffness increases (and also BIC). In this case there will be a good correlation between ISQ and BIC.

 

In Dense Bone

When the initial stability is high (e.g. above 75 ISQ), osseointegration will not add stability to the implant in a significant way. Even if the BIC is increasing, the implant stability will not change much, which is reflected by the ISQ value. In this case, the correlation between BIC and ISQ will be poor.

 

Failing Implants

For implants that does not integrate, the stiffness will decrease and the stability will go down. This will be reflected by the decreasing ISQ value. The above implies that it is possible to have relatively high BIC but low ISQ in soft bone, and low BIC with high ISQ in dense bone.

ISQandBICillustrated

 

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References

The relationship between resonance frequency analysis (RFA) and lateral displacement of dental
implants: an in vitro study
Pagliani L, Sennerby L, Petersson A, Verrocchi D, Volpe S & Andersson P
Journal of Oral Rehabilitation 2012

Implant Stability Quotient (ISQ) vs Direct in Vitro Measurement of Primary Stability (Micromotion):
Effect of Bone Density and Insertion Torque
Paolo Trisi PhD, Teocrito Carlesi DDS, Marco Colagiovanni DDS, Giorgio Perfetti MD, DDS
Journal of Osteology and Biomaterials, Volume 1, Number 3, 2010

Tissue integration in Oral and Maxillo-Facial Reconstruction
Editor: D. van Steenberghe Co-editors: T. Albrektsson, P.-I. Brånemark, P.J. Henry, R. Holt, G. Lidén
Proceedings of an International Congress May 1985, Brussels. Excerpta Medica 1986

ReferencesReosseointegration of mechanically disintegrated implants in dogs: mechanical and
histometric analyses
Sungtae Kim, Jung-Seok Lee, Ji-Wan Hwang, Min-Soo Kim, Seong-Ho Choi, Ui-Won Jung
Journal: Clinical Oral Implant, Year: 2013, Issue, chapter, pages: 2013, 1–6

The relationship between initial implant stability quotient values and bone-to-implant contact ratio in the rabbit tibia
Park IP, Kim SK, Lee SJ, Lee JH.
Journal: J Adv Prosthodont. Year: 2011
Clinic: Department of Prosthodontics and Dental Research Institute, School of Dentistry, Seoul National, University, Seoul, Korea. Issue, chapter, pages: Jun;3(2):76-80. Epub 2011 Jun 30.

Determination of primary stability: a comparison of the surgeon’s perception and objective
measurements
Degidi M, Daprile G, Piattelli A.
Int J Oral Maxillofac Implants. 2010 May-Jun;25(3):558-61

The relationship between resonance frequency analysis (RFA) and lateral displacement of dental
implants: an in vitro study
Pagliani L, Sennerby L, Petersson A, Verrocchi D, Volpe S, Andersson P.
J Oral Rehabil. 2012 Dec 28. doi: 10.1111/joor.12024. [Epub ahead of print]

Implant Stability Quotient (ISQ) vs direct in-vitro measurement of primary stability (micromotion):
effect of bone density and insertion torque
Trisi P, Carlesi T, Colagiovanni M, Perfetti G
J Osteol Biomat 2010; 1:141-151