Revisiting Hanau's Quint: a novel digital analysis of the laws of articulation in complete dentures

The purpose of this study was to evaluate the interrelationships among the determinants of Hanau's Quint - condylar guidance, occlusal plane, compensating curve, incisal guidance, and cusp height - according to the laws of articulation, using a novel digital method.

Fully edentulous casts with 9 sets of occlusion rims (7, 8, and 9 inches curvature; standard, +5°, and -5° inclination) were mounted on a semi-adjustable articulator to simulate analog experimental conditions (AECs). The same settings were reproduced in a 2-dimensional virtual articulator in a lateral view (Adobe Photoshop), with the addition of cusp height as a variable, to generate digital experimental conditions (DECs). Whenever an increase in one determinant produced occlusal disharmony, other factors were modified until bilateral balanced occlusion (BBO) was reestablished. The results were compared with Hanau's predicted interactions.

Both analog and digital methods demonstrated consistent interrelationships among the occlusal plane, compensating curve, condylar guidance, and incisal guidance, as described in Hanau's Quint. Cusp height, tested digitally, showed a predictable compensatory role.

The interrelationships among the determinants of Hanau's Quint in achieving BBO were validated digitally using a simple and reproducible digital methodology confirmed by an analog articulator. This study may help clinicians better understand BBO and Hanau's principles in complete denture treatment planning.