Date: 30 Jul 2012

Kinematic comparison of different incisal tables used for anterior guidance reconstruction

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Abstract

Purpose

Conventional articulators allow the user to adjust the inclination of the incisal table according to reconstruction principles. This fact suggests the adoption of an incisal table which exploits an appropriate curvature related to the individual incisal concavity by the reciprocal motion of the incisors. The aim of this study was to compare different incisal tables by a kinematic analysis of the protrusion motion.

Materials and methods

A parametric planar multibody model of the articulator (reference SL Gamma Dental) was developed by means of the implementation of the contact equations in the sagittal plane both for the condylar and incisal pin/tables guides. Through the use of the parametric model, the equations of contact and motion were mathematically shown for the different devices used in the present study.

Sequenzial incisal tables, individual anterior guidance unit and adjustable curvature were used for the comparison. All the tests were made using three shapes of condylar guidance (CI) with different sagittal condylar inclination (SCI). The numerical parameters of tables were processed and compared to the trajectory of the upper shape of the standard incisal by a mean deviation factor (MDF).

Results

The value of the MDF decreased from a mean value of 0.13 when a flat table was used to a mean value of 0.08 when an adjustable curvature device was used. In all cases the curvature was higher in the first part of the protrusion and progressively decreased during the protrusion path. The variation of the eminence angle may affect the inclination of the ideal incisal table but the curvature is imperceptibly affected by this parameter.

Conclusions

The comparison between three incisal tables showed a better matching of the adjustable curvature of anterior guidance showing full agreement with the results.