Table of Contents

Roundtable
Implants

Inside Dentistry

March 2009, Volume 5, Issue 3
Published by AEGIS Communications

Predictable Restorative Planning: The Use of a Contemporary Articulator and Facebow

Leonard A. Hess, DDS

One commonality between the patient and the dentist is the desire for predictability. The patient always appreciates treatment that goes smoothly with little perceived interference. And the dentist knows that predictable care is usually more profitable care. Crowns that need to be re-glazed, re-contoured, or remade lessen or eliminate the profitability of a procedure. And restorations that need a lot of adjustment are sometimes viewed by the patient as having been compromised. After all, was this restoration not “custom made” for the patient?

As human beings, we are all drawn to a path of least resistance. When this principle is applied to clinical dentistry, the end result is usually none the better. What is saved by cutting corners is typically lost many times over through lessened quality, redundant time, frustration, and added costs.

One way in which many clinicians could improve is with the consistent use of an articulator and facebow-mounted models. Casts that have been mounted without a facebow are of little diagnostic value. Once the casts are opened on the articulator, their relationship will be lost. The actual arc of opening has not been recorded.1 The simple use of a jig or stick to transfer the incisal edge position horizontally accomplishes that only. A facebow allows the three-dimensional transfer of the relationship of the maxilla to the temporomandibular joint. And it allows the reproduction of the axis of condylar rotation.2 This becomes critical when mounting casts from an open bite record such as a centric relation record. What can then be clearly recognized is the position of the incisal edges in relation to the joints, the maxillary occlusal plane, and the closing arc created by the condylar axis. If the starting point of restoration planning is incorrect, the end result will reflect this lack of precision. This will be readily evident in cases where vertical dimension has been altered. The same holds true in cases where the anterior guidances have been restored, such as in cosmetic rehabilitation. A good example is a situation where teeth Nos. 6 through 11 are restored with crowns. At the laboratory, the casts are mounted on a simple hinge articulator using a bite stick for the horizontal reference (Figure 1). Everything fits great on the models, but requires excessive adjustment of the lingual contours in the mouth. This results from lack of registration of the correct condylar axis of closure.

In the past, facebows and articulators were often complicated devices that were time consuming to use and intimidating. This article highlights the use of the Denar Combi II Articulator System and Denar Slidematic Facebow by Whip Mix Corporation (Louisville, KY). These instruments are accurate and were designed for simplicity and efficiency. The new Combi II articulator (Figure 2) has many significant features, which include:3

• a progressive side shift fixed at 15°
• condylar inclination adjustable up to 60° (Figure 3)
• a centric latch that allows separation of the bows and a positive lock in centric relation in both the open or closed position

The fixed progressive side shift, being greater than can occur anatomically, eliminates the possibilities of balancing side interferences. When using the Combi II, the only adjustment in need of programming is the condylar inclination. This is easily recorded with a simple protrusive bite record (Figure 4). Gone are the days of difficult-to-program, fully adjustable articulators. To program the Combi II, all that is needed is a facebow record, a protrusive bite record, and, when necessary, a centric relation record (Figure 5).

The Slidematic Facebow (Figure 6) is also a highly accurate yet simple instrument to add to an armamentarium. It features the following:4

• a speed slide gear that allows an effortless assembly of the bow onto the patient
• ergonomically positioned tightening screws
• a separate transfer jig and bow design to allow separation for later mounting or shipment to the laboratory
• a reference plane locator and marker (Figure 7)
• a built-in horizontal reference pointer to consistently align the bow (Figure 8). This is especially helpful when multiple facebows are necessary over time, such as during major restorative cases.

With the ease of use, the Slidematic facebow record can be confidently delegated to auxiliary staff members. The transfer jig can then be easily transferred to the Combi II articulator using the included index. After mounting the maxillary cast with the facebow jig, the lower can be mounted (Figure 9) and the condylar inclination set with the protrusive record (Figure 10). The case is then ready for analysis and the diagnostic phase.

Conclusion

The days of cumbersome, confusing, and overcomplicated articulators are in the past. Properly executed case planning and restorative techniques should include the use of facebow-mounted models on a quality articulation device. If one is in search of ever-increasing predictability and profitability, a consistent and thorough approach is needed. This should include the ability to analyze and create restorations based on the unique anatomical and functional relationship for that patient.

Disclosure

Leonard Hess, DDS, has received honoraria from Whip Mix Corporation.

References

1. Dawson P. Functional Occlusion: From TMJ to Smile Design. St. Louis, Mo; Mosby. 2006:233-259.

2. Hess L. The relevance of occlusion in the golden age of esthetics. Inside Dentistry. 2008;4(2):36-44.

3. Manufacturer Instruction Manual. Denar Combi II Articulator System. Whip Mix Corporation, Louisville, KY.

4. Manufacturer Instruction Manual. Denar Slidematic Facebow. Whip Mix Corporation. Louisville, KY.

About the Author

Leonard A. Hess, DDS
Private Practice
Monroe, North Carolina