Periotest method: implant-supported framework fit evaluation in vivo

In implant prosthodontics an accurate fit of the framework to the supporting implants is paramount. However, microgaps occur, unknown to the clinician until complications arise that implicate errors in fit. Therefore prosthodontics would welcome a tool or instrument that provides an objective evaluation of the fit at the implant prosthodontic interface.

This clinical investigation determined whether a correlation existed between the laboratory laser measurement of the abutment analog-framework fit and the intraoral abutment-framework fit as measured by the Periotest method.

Fifteen subjects received implant-supported remote fixed partial denture supported by five (11 subjects) or six (4 subjects) implants in the mandibular jaw opposed by a complete maxillary denture. Laser videography was used to quantify the fit of the framework to its respective master cast with six measurements, while the fit of the framework in the mouth was quantified with the Periotest method. Data were statistically analyzed with correlation analyses and multiple regression.

The overall correlation coefficient between the two methods was r = 0.51. Regression analysis of variance revealed that the intercept of the laser videography measurement was significant (p < or = 0.05). The mean Periotest values and standard deviation for the abutment-framework interface were negative (-7.3 +/- 1.2). The variance in part for the Periotest values was explained by the misfits in the vertical axis (delta Z, +0.471) and in the misfit direction of the centroids in the x-y plane (X-YVD, -0.244).

There was no single variable among the six measurement variables that strongly correlated with the periotest method in the identification of mistfit at the bearing surface as indicated by the Periotest value measurements. The misfit laser variables that were weakly correlated to the Periotest values should be observable clinically with greater scrutiny.