The effect of articulator hinge axis precision and mounting plate repositioning on occlusal contacts: an in vitro study

The purpose of this study was two-fold: (a) to evaluate articulator hinge axis precision, and (b) to study the effect of removing and replacing mounted casts on occlusion. One Artex^® AL (AR) and one Whip Mix^® (WM) articulator was selected. Impact-resistant resin study models were mounted in maximum intercuspation position on the magnetic plate of AR (randomly selected): (a) for hinge axis precision, AR was opened and closed 10 times with the casts secured and 10 records were made, and (b) for the effect of repositioning mounting plates, mounted models with their respective plates were removed and repositioned 10 times and 10 records were made. Upon completion, models were dismounted and remounted on WM with screw-retained mounting plates and the whole procedure was repeated. Areas of interest were the second premolars and first molars bilaterally. Light transmitted through records was analyzed by a computerized image analysis program. WM showed greater deviation in hinge axis precision; AR was significantly more consistent. For AR, removing and replacing the mounting plates introduced statistically significant differences at the right second premolar, first molar, and left second premolar areas (t = 3.846, P = 0.001; t = 3.540, P = 0.002; t = 2.395, P = 0.028; respectively); for WM, differences were observed at the first molar area (t = 143.000, P = 0.005). AR reproduced cast positions more consistently than WM. Removal and replacement of plates introduced a difference causing further occlusal changes. Parole chiave: articulator, hinge axis, interocclusal recording material, mounting plates