This lecture details instrumental techniques for diagnosing and treating Craniomandibular Dysfunction (CMD). It demonstrates quick chairside methods for hinge axis location and maxillo-mandibular relationship recording using face bows (SAM articulator transfer) and intraoral Gothic arch tracing (needle point registration) to define the therapeutic position for splint fabrication. The presentation covers highly accurate methods, including laboratory-fabricated resin devices that minimize vertical dimension increase and electronic jaw motion analysis (JMA), which provides detailed kinematic data for articulator programming. Two clinical case studies are presented: one involving hypermobility and subluxation treated with a stabilization splint, and another concerning CMD secondary to pituitary adenoma, emphasizing the necessity of precise anterior guidance in anterior open bite cases.
Instrumental Analysis and Treatment Techniques for Craniomandibular Dysfunction (CMD)
0:00 Introduction to Chairside Analysis: The lecture focuses on instrumental analysis techniques and quick treatment procedures usable in a typical dental practice for craniomandibular dysfunction (CMD).
0:26 Chairside Registration Setup: The simple chairside method for achieving a therapeutic splint position involves using interocclusial/interoral needle point registration devices, typically fabricated quickly using impression material (though resin is more accurate).
1:56 Face Bow Placement and Transfer: Demonstrates the placement of a face bow (SAM system) connected via a transfer fork to the upper dental arch. This allows the accurate recording of the condylar position relative to the hinge axis.
3:17 Articulator Mounting (Upper Cast): The face bow is transferred to the articulator (SAM), ensuring the upper cast is precisely mounted in relation to the hinge axis. Plaster is used as temporary support to prevent deformation caused by the weight of the cast.
6:08 Intraoral Tracing (Gothic Arch): The intraoral needle point tracing device is inserted. The patient performs protrusive and lateral movements to draw the Gothic arch.
Key Takeaway (7:40): The desired therapeutic position for splints is typically located slightly anterior to the tip of the Gothic arch (centric relation/retrusive movement limit).
9:45 Capturing the Therapeutic Position: The position slightly anterior to centric relation is secured using a holding device (fixed by wax/screws) and registration material placed between the arches.
Detail (10:11): A disadvantage of the fast, impression-material based technique is the requirement for a larger vertical dimension increase compared to resin-based devices.
11:27 Mounting the Lower Cast: The lower mandibular model is mounted to the articulator using the recorded interocclusial relationship device.
13:31 Backward Check for Accuracy: A crucial step involves creating a new interocclusial record using the mounted casts (e.g., heated Beauty Pink wax). This record is placed back into the patient's mouth. If the patient reports balanced, equal contact, the initial registration is deemed accurate.
18:40 Splint Fabrication and Verification: The final splint is checked for stable static occlusion and dynamic occlusion (anterior guidance, no posterior contacts during lateral/protrusive movements).
Takeaway (19:29): Deflective occlusal contacts on a splint suggest a technical error in the laboratory fabrication/mounting procedure, not an incorrect therapeutic position.
22:01 Improved Precision via Lab Devices: Higher precision is achieved using laboratory-fabricated, resin-based needle point tracing devices with retaining clasps (e.g., ball clasps). These minimize the necessary vertical dimension increase, thereby reducing errors related to arbitrary hinge axis location.
25:30 Determining Protrusive Joint Movement: Information on joint movement is needed for articulator programming. This can be achieved either through advanced tracing devices or by taking interocclusial records in protruded mandibular positions.
28:14 Adjusting Condylar Guidance: Demonstrates adjusting the condylar guidance element on the articulator using a protrusive interocclusial record until it makes contact with the condylar element, allowing the clinician to read and set the patient's specific movement degree.
31:33 Electronic Jaw Motion Analysis (JMA): Electronic devices (such as the opto-electronic Zebra device) are recommended for superior accuracy because they register mandibular movement simultaneously on both sides, tracing the full Posselt diagram and providing precise programming values for the articulator.
38:45 Digital Treatment Workflow: The entire procedure, including splint fabrication, can be performed using a fully digital workflow based on intraoral scans, including dynamic scanning to register movements.
40:22 Case Study 1: Hypermobility and Subluxation: A 40-year-old female patient with general hypermobility and subluxation. Functional panoramic radiograph showed condyles moving far in front of the eminentia. Treatment included a stabilization splint and physiotherapy.
Outcome (44:49): After 11 years, hypermobility remains, but subluxations ceased, and the patient is largely pain-free with regular checkups.
44:58 Case Study 2: Pituitary Adenoma and Open Bite: A patient with CMD resulting from disturbed mandibular growth (pituitary adenoma), leading to an anterior open bite and muscle pain.
Treatment (47:47): Treatment involved a splint with a significant height in the anterior region to achieve anterior guidance, which is crucial in managing CMD associated with anterior open bites.