Abstract
A dental operating microscope （DOM） has a low degree of positioning flexibility because an eyepiece is used for observations and mirror techniques are often required for viewing the operative field. We developed a new DOM technique, termed the three-dimensional （3D） microscopic method （TMM）, with a connection to a monitor that can display stereoscopic 3D images. In this study, differences in magnification characteristics obtained using TMM and a conventional microscopic method （CMM） were compared along with their effects on the precision of hand instrument usage under a magnified field of view. Five endodontists evaluated the resolution and depth of field （DOF） of the CMM and TMM using dedicated measurement targets. Furthermore, 15 dental residents used both methods to assess a target using a hand instrument, and two evaluators measured the distance between the target’s center and that of the resultant hole to evaluate the effects on the precision of hand instrument usage. Resolution was significantly higher for CMM than TMM （p＜0.05）, although CMM had significantly lower DOFV values at Mob＝0.4x （p＜0.05）. Furthermore, CMM had significantly lower DOFH values than TMM at Mob＝0.4x and 0.6x （p＜0.05）, whereas TMM had significantly lower values than CMM at Mob＝1.6x （p＜0.05）. No significant difference was observed between TMM without and CMM with the mirror technique （p＞0.05）. The results suggest that TMM used for magnification is less prone to differences in clinical results compared with CMM because it allows for more direct viewing while maintaining the same level of procedural accuracy.
