Learning Objectives: Basic physical principles for the correlation between abutment length and Implant Stability Quotient (ISQ) How these principles translates to a laboratory measurement of the correlation of ISQ with abutment length. Implications of the measurements for future studies and clinical measurements.

Introduction: Objective: To quantify the influence from abutment length on measured Implant Stability Quotient (ISQ) for a bone anchored hearing implant system.

Method: Design: Laboratory measurements on temporal bones. The Ponto Wide Implant (Oticon Medical AB, Askim, Sweden) was implanted in temporal bones and measurements of ISQ were made on implant level and for the 6 mm, 9 mm, 12 mm and 14 mm abutments using The Osstell ISQ and SmartPegs (Osstell, Göteborg, Sweden) type 09 (implant level) and type 55 (abutment level). By varying the insertion torque and implantation site, a broad span of implant level ISQ measurements was obtained and compared with the measurements on abutment level. The validity of the data was secured by measuring implant level ISQ before and after measurements on abutment level.

Results: For each abutment length a linear relationship existed between the implant level and the abutment level ISQ throughout the span of ISQs. The slopes for the linear correlations were similar for the different abutments lengths. The relationship for the ISQ as a function of abutment length throughout the span of implant level ISQs was also linear and the slope was measured to be -3.1 ISQ/mm ± 0.2 ISQ/mm (standard error of estimate).

Conclusion: The measured correlation between ISQ on implant and abutment level for a bone anchored hearing implant system revealed that the difference in ISQ for different abutment lengths is an additive constant independent of implant level ISQ. This relationship can be used for pooling mean results in clinical studies where different abutment lengths are used.