Getting the plates parallel on the gothic arch tracing

The central bearing /gothic arch tracing apparatus works properly when the two plates are approximately parallel to each other, and the central bearing point is contacting with the jaws at the optimum vertical dimension.

One way to ensure this is to use interim wax rims at the second impression stage. The rims, made entirely of wax including the bases, are trimmed in the clinic roughly to the correct occlusal vertical dimension and centric relation. The dental technician trims back the wax sulcus extensions of these preliminary rims so that they will sit nicely on the new working casts, allowing the central bearing plates to be correctly positioned, vertically and horizontally. These are used to generate the jaw relation record in retruded jaw relation at the chosen vertical dimension, and thus for mounting the working casts. Conventional wax rims are then made in the lab and trimmed in the clinic to indicate tooth position, lip support, test speech, etc, as usual, ideally with the help of Alma Gauge readings.

Denture Blog 36

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