Lucia Jig or a Leaf Gauge? Which one is best? A couple of tools that have been used throughout the years to aid dentists in seeding the condyles and taking or recording a centric relation bite record in addition to bimanual manipulation or in conjunction with bimanual manipulation are the Lucia Jig and the Leaf Gauge.
The Lucia Jig
The Lucia Jig can be made from any acrylic-type wafer or Jigs can be purchased and relined with compound or with a PVS-type rigid bite registration material. Those are centered on the maxillary central incisors and a devisor tool is used to make those flat and parallel with the patient's occlusal plane like a whale tail or even a simple tongue depressor. While the majority of patients can be manipulated or hinged comfortably to locate their centric relation position, the Lucia Jigs are also helpful when a patient has really tight muscles and they are challenging to manipulate. The Lucia Jig can be used usually after about 5 or 10 minutes of the patient relaxing on the Lucia Jig that's separating all of their teeth. Then they will be able to be loaded comfortably so that we can verify that they are in centric relation. So probably the two biggest advantages of the Lucia Jig are that it is flat and also that it is made parallel with the patient's occlusal plane.
The Leaf Gauge
The Leaf Gauge, on the other hand, is a series of shims or leaves and each leaf is about 1/10 of 1 ml in diameter, and those can be made thicker or thinner by altering or dialing in the number of leaves that we use to separate the patient's teeth again on the maxillary central incisors, and this is used to separate or disclude the patient's back teeth and create space if we want to take a centric relation bite record. The disadvantage of a Leaf Gauge is that it can have a tendency to distalize the condyles especially in a patient with a deep overbite, and anything that puts force on the lower front teeth or on the mandible that can distalize the condyle can move the condyle down and back in the fossa and prevent us from recording an accurate centric relation bite record. So for most patients, the advantage would have to go to the Lucia Jig.
Learn more about how to treat your patients in centric relation by taking our foundational course, Functional Occlusion - From TMJ to Smile Design.
