When the occlusal rims return from the dentist, they provide the technician with a recording of the patient’s bite. The next step is to replicate the patient’s maxillomandibular relationship in the lab using the information recorded on the occlusal rims. This is achieved with the use of an articulator, which is adjusted to approximate both of the patient’s temperomandibular joints and the position of the jaw in centric relation.
In order to simulate the dentist’s recording of the patient’s jaw relationship (and thus give us centric), Professor Cottone placed our occlusal rims on an identical set of casts which were mounted on a designated, pre-adjusted articulator – the “patient”. He trimmed our maxillary and mandibular occlusal rims as necessary to achieve centric occlusion and sealed them together in a closed position – centric.
Each of us ground two perpendicular notches (an “X”) across the bottom of our maxillary and mandibular casts in order to provide purchase for plaster, as well as registration and stability within our articulators. We then applied separator to the bottom of each cast.
Once our occlusal rims were sealed in centric, we returned them to our own casts and mounted them in our semi-adjustable articulators. To replicate the patient’s vertical dimension, each of us adjusted our anterior guide pin to the red mark and made sure it was contacting the anterior guide table. We aligned the incisal midline of our occlusal rims to touch the incisal guide pin of the articulator and used a rubber band as a reference point to center our models laterally and level them. We built up a plaster of paris base to affix the mandibular cast to its respective plate in stages, careful to keep the model level and raise it high enough. We then repeated the procedure on top, affixing our maxillary casts in the same way. Finally, we dampened and sanded the plaster of paris to tidy everything up.
With our models articulated, we were free to separate our maxillary and mandibular occlusal rims once again and begin arranging our teeth.
