While many in the profession maintain that bimanual manipulation is too hard to learn, after they are taught the correct technique, dentists attending The Dawson Academy find it not only learnable and repeatable, but choose it as their preferred method for finding and verifying centric relation.
One of the keys to success with bimanual manipulation is visualizing the anatomy of the joint, and knowing and understanding the proper definition of centric relation is critical to this ability. There are many misinterpretations of the true definition of CR; in fact Wikipedia lists 16 different definitions.
Dr. Dawson defines CR as, “ the relationship of the mandible to the maxilla when the properly aligned condyle-disc assemblies are at their most superior position against the eminentia, irrespective of tooth position or vertical dimension.” Understanding this definition, visualizing the location of the muscles and observing whether the muscles are relaxed makes it fairly easy to gently guide the patient into CR.
Here are a number of common errors that are somewhat universal and how to avoid them:
Error: Incorrect doctor and patient position.
Proper positioning starts with the patient reclined with their chin-up. This position allows for good visualization and easy placement of our hands. The dentist needs to be comfortable with relaxed shoulders, straight wrists, arms parallel to the floor and patient’s head braced. We want the patient to relax, so that they can be GUIDED, not FORCED, into CR. When we are relaxed, patients tend to be relaxed.
Error: Placing the fingers over the entire mandible.
This results in a force vector, which tends to distalize the condyle versus “turning the doorknob.” Proper placement begins with identifying the angle of the mandible, placing the small finger just distal to the angle and aligning the other fingers tight together along the lower border of the mandible. The thumbs are then positioned in the notch superior to the mandibular symphysis, forming a “C”. This creates a vector from the patient’s chin pointing toward the patient’s chest.
Error: Jiggling the mandible or rushing the patient into CR.
With almost zero pressure from the dentist, have the patient hinge open & closed in rotation, never letting the teeth touch. When the hinge movement is consistent, have the patient stop hinging and gently load the join with light, medium and firm pressure.
Finally, Lucia jigs are wonderful tools to help develop proper technique and confidence.