Objectives: The purpose of this study was to examine the usefulness of Periotest and Osstell Mentor (a resonance frequency analysis) as nondestructive analytical tools for determining implant stability in clinics, to evaluate the precision of both instruments, and to determine the applicability of these measured values as clinically relevant indices.

Study design: Four adult mongrel dogs weighing about 12 to 15 kg were used in this study. Bilateral extractions of the first through the fourth mandibular and maxillary premolars were performed and a total of 48 commercially pure titanium screw implants (USII Plus; OSTEM Implant, Seoul, Republic of Korea) were placed at 4 weeks after extraction. All implants (10 mm length and 3.3 mm diameter) were self-tapping and surface-treated with resorbable blast media (RBM). Periotest values (PTVs) obtained from Periotest, and Implant Stability Quotient (ISQ) obtained from Osstell Mentor, were measured at the time of implantation, and 3 and 6 weeks after implantation. At 3 and 6 weeks after implantation, 4 dogs were humanely killed and histomorphometric analysis was performed. The new peri-implant bone formation rate (NBFR) was measured.

Results: The PTV value was lower and ISQ value was higher at 6 weeks when compared with data collected at 3 weeks after implantation. The PTVs of the maxilla were higher than the mandible and the ISQ values of the maxilla were lower than the mandible. Based on the NBFR, the 6-week group showed higher bone formation when compared to the 3-week group, correlating to the observed PTV and ISQ values. Additionally, the NBFR was higher in the maxilla than the mandible. No significant difference between PTV and ISQ was also observed when PTV and ISQ were compared to NBFR.

Conclusion: The results indicated that the Periotest and Osstell Mentor, both noninvasive diagnostic devices, were useful and comparably reliable, showing a strong association with each other in assessing implant stability.