Wireless Versus Classic Periotest , Reproducibilty Measures: In-Vitro study

Problem: There are several instruments used to assess the status of the bone-implant complex -- each with studies supporting their clinical use. A new wireless and a classic/wired Periotest are currently available. Validity of research requires that the reproducibility of the "measuring instruments" be determined using standardized test specimens. Objectives: Several questions associated with the reproducibiliy of Periotests need to be assesed. These include the reproducibility of: 1) each device, 2) between each instrument type -- (wireless vs wired) --, and 3) when used by several different evaluators. Methods: Metal disks of different thicknesses/flexibility were placed over the ends of three hollow cylinders -->6 test specimens. The disks were attached by a metal ring. This ring served as a pre-test calibration device, to insure insturment was functioning properly, prior to each test sequence. Ten evaluators tested each disk using each instrument and the results recorded. Results: 1) PTVs from the pre-test calibration ring did not vary for each instrument; wireless mean= -8 PTVs, var=0, wired mean= -7, var=0, 2) the pre-calibration PTVs differed slightly between the wireless and wired [mean=-7.5, var=0.5], 3) slightly larger variations for all evaluators: wired; Disk 3-A: mean=19.5,[SD=0.7], 3-B:mean=-7(SD=0), 4-A:mean =8.9 (SD=0.9), 4-B:mean= -7(SD=0), 5-A:mean=12.95,[SD=1.7], 5-B:mean=3.7[SD=0.9]-- wireless: 3-A:mean=22.6 (SD=0.8), 3-B:=mean=-7.6(SD=0.7), 4-A: mean=10.1(SD=0.2), 4-B:-8(SD=0), 5-A:mean=15.8(SD=0.5),5-B: mean=4.2(SD=0.5). Summary: Repeated PTVs for the calibration specimen were exactly the same for each instrument-- wired (-7) or wireless (-8). There was one PTV difference between values for the wired vs the wireless device for the calibration specimen. Repeated tests of the different flexibility disks produced only slight variations among 10 different evaluators -- which was quickly corrected by the evaluator. Conclusions: Both the wired and wireless instruments tested appear capable of providing valuable, reproducible clinically relevant information related to long-term implant stability.