The Lucia Jig is a technique that allows clinicians to obtain an accurate bite registration by stabilizing the mandible in a harmonious position. This position is essential to the dental laboratory’s ability to accurately fabricate an appliance that needs occlusal coverage. The Lucia Jig technique promotes neuromuscular programming and works by separating the posterior teeth so that the pterygoid muscle releases, allowing the condyles to be seated in the optimal position. A Lucia Jig gives the patient’s incisor teeth a platform on which to occlude, while the posterior teeth remain out of contact, thus relaxing the muscles.
The Lucia Jig procedure is straightforward and requires a silicone bite registration paste for use with a syringe. The material has a relatively short setting time, with a maximum cure time of one minute. Once the material is set, it is trimmed and will remain dimensionally stable so that it can easily be sent to the dental lab.
Choosing the Right Lucia Jig
The choice of Lucia Jig depends on the vertical opening of the patient’s back teeth, which can be determined using the standard jig. When the vertical opening between the back teeth exceeds 2.5 mm, the Class II Jig should be used to reduce this opening. It may be necessary to use the Lucia Jig on the lower centrals for patients with irregular lower incisors. Doing so ensures that the Jig functions properly against the upper incisors.
Step-by-Step Instructions for Using the Lucia Jig
- Using a small amount of tray adhesive, carefully coat the curved surface of the Jig.
- With the syringe, disburse the silicone bite registration paste into the curved section of the Lucia Jig, taking care not to overfill it.
- Situate the Jig on the upper centrals, and ask the patient to bite and hold. Allow the material to set before removing the Jig.
- Once the Jig is removed, trim the excess material with a lab knife. It is essential to remove excess material that extends over the edge of the Jig. If the patient occludes on the bite registration material it could get in the way of the patient making smooth movements as you check their occlusion.
Check to make sure the muscle is relaxed
- Place the Jig back into the patient’s mouth and ask the patient to bite down on the Lucia Jig before sliding forward, backward, and squeezing. Next, ask the patient to repeat these movements and check if they feel any tension or tenderness.
- If the patient doesn’t experience any tenderness, then the pterygoid muscle is properly relaxed.
- If the patient experiences tenderness or a feeling of tension, more time is needed to allow the muscle to relax and the condyles to fully seat. It can take up to twenty minutes for the muscle to relax. If the patient continues to feel discomfort, then they may have problems with their joints.
Ensure the lower incisors are correctly and evenly contacting the Lucia Jig
- To confirm that the incisors are contacting the Jig correctly, re-seat the Jig in the patient’s mouth and place articulating paper between the Jig and the lower teeth. Ask the patient to bite down gently and to slide their lower centrals forward and backward several times, so the contact is clearly marked on the Jig.
- Carefully remove the Jig and check to see if the articulating paper has marked both edges of the Jig. If there’s only a line on one side of the Jig, adjust it with an acrylic bur and then repeat the previous step. Once the articulating paper evenly marks the Jig, proceed to the next stage of the process.
Determine the retruded position
- Re-seat the Jig in the patient’s mouth and ask them to bite down before sliding forward, backward, and squeezing.
- Next, ask them to repeat these motions and to hold before opening their mouth slightly. Place articulating paper between the patient’s lower incisors and the Jig, and ask the patient to tap their teeth three times.
- Check that the patient’s lower centrals contact the marks recorded with the articulating paper, as this ensures that the patient’s bite is in centric relation.
Making the bite registration
- Thoroughly dry the patient’s teeth. The bite registration material adheres more easily to dry teeth. Situate the Lucia Jig correctly and ask the patient to open their mouth.
- Use a syringe to insert sufficient silicone bite registration material onto the second molars, moving forward until you have covered the teeth up to the cuspids on each side of the mouth. Use enough material to create a band of silicone approximately 4 to 5 mm in thickness. The patient should close their mouth slowly, so they bite on the marks recorded on the Jig, and firmly squeeze their teeth together. It is essential that the patient tightly squeezes their teeth to properly seat the condyle using the temporalis, masseter, and pterygoid muscles.
- Check that the patient’s lower centrals are positioned on the most posterior marks recorded on the Lucia Jig. This will show whether they have closed their mouth in the correct location.
- When the bite registration material is set, the patient opens their mouth in order to remove the bite registration and Lucia Jig.
- Carefully check the bite registration to make sure it provides adequate buccal and palatal cusp records of the lower teeth.
Trimming the Bite Registration
It is essential to trim the bite registration to fit accurately on the model. Trimming the bite record ensures that once the models are seated with the bite record they can’t move. Trim the bite record with a diamond disc or with a knife. Adjust the flanges with fine sandpaper until the cusp depth is approximately 1.5 mm. Remove the fossa depths and marginal ridge detail with an acrylic bur, as only the cusp depths need to remain. Once the bite record is trimmed, check it on the model. It should seat accurately, and the model should not move.
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References:
https://www.greatlakesortho.com/content/files/resources/UsingtheLuciaJigforAccurateBite_S220.pdf
https://www.ncbi.nlm.nih.gov/pubmed/23019085