Influence of different loupe systems and their light source on the vision in endodontics

The aim of this study was to evaluate the performance of Galilean and Keplerian loupes in the endodontic lumen with and without integrated light. Although the use of an operating microscope is widely recommended in endodontics it is uncertain whether an adequate loupe system with coaxial light source might replace the microscope for some endodontic work. Twenty-four dentists (age 27–64 years) underwent a miniaturized visual test inside the endodontic lumen of a natural molar: at the canal entrance, 5 mm inside the canal, and at the apex. The tooth was mounted in a phantom head in a simulated clinical setting. The naked eye (negative) and the microscope 6× (positive) served as control groups, and Galilean loupes 2.5× and Keplerian loupes 4.3× with and without a coaxial light source as experimental groups. A structure of 0.05 mm corresponding to the smallest instrument (06) was the threshold for sufficient vision. The loupe type, coaxial light source and the dentists’ age had a statistically significant influence at all locations. None of the loupes helped to visualize structures at the apex. At the canal entrance, the visual threshold was reached by dentists < 40 years with Galilean loupes, by dentists ≥ 40 years with Keplerian loupes, with and without coaxial light. Dentists < 40 years detected structures < 0.05 mm inside the root canal with Keplerian loupes and coaxial light. The microscope offered highly superior results. The naked eye was insufficient to reach the visual threshold at any location.