Tactile misfit detection ability at the implant-abutment interface of internal connection dental implants: an in-vitro study

Objective: The aim of this in-vitro study was to investigate the tactile assessment ability at the implant impression-taking stage.

Methods: Thirty clinicians (18 novices, 12 experts) were included for a tactile fit assessment by using a used/new probe (tip diameter 100 µm/20 µm). Six implant replicas and related impression copings of two internal connection implant systems were used, each with a perfect fit (0 µm) and defined vertical micro gaps of 8, 24, 55, 110 and 220 µm at the interface. Statistical analysis was performed using descriptive methods and non-parametric tests with a focus on specificity (ability to detect perfect fit), sensitivity (ability to detect misfit), and predictive values. P-values <5% were considered statistically significant.

Results: The tactile assessment showed a mean total sensitivity for the Straumann and Nobel Biocare systems of 83% and 80% with a used probe, and 91% and 92% with a new probe, respectively. The mean total specificities were 33% and 20% with a used probe and 17% and 3% with a new probe, respectively. No statistical significance was observed between novice and expert clinicians concerning their tactile assessment ability.

Conclusions: The ability to detect a perfect fit (specificity) with a probe was very poor for both implant systems and impaired with the use of a new probe. The use of a new probe improved the gap detection ability (sensitivity) significantly at the expense of the specificity. A combination of additional chairside techniques with training and calibration could improve clinicians' ability to correctly assess the fit/misfit at the implant-abutment interface.