The Essential Elements of Occlusal Appliance FabricationBy Darin Dichter on October 20, 2022 | 1 comment
Occlusal appliances are commonly used in a restorative practice. From the patient's perspective, the most common appliance is the humble night guard or other protective appliance. Protecting the dentition from attrition is only one of many uses for an occlusal appliance. There are also common diagnostic or therapeutic indications for using occlusal appliances, including:
- Diagnosing muscle or joint pain
- Deprogramming muscles/managing occlusal-muscular pain
- Managing pain from the TM joint
- Advancing the mandible
Once the need for an occlusal appliance has been prescribed, the clinician must select an appropriate design and begin the process of occlusal appliance fabrication.
Options for occlusal appliance design include:
- Anterior bite plane (Fig. 1, left).
- Full coverage appliance in fully seated condylar position (centric relation) with ramped guidance (an example is a Michigan-style appliance).
- Full coverage appliance in fully seated condylar position and a flat occlusal guidance (Fig. 1, center).
- Full coverage appliance in a position other than a fully seated condylar position with a ramped guidance.
- Full coverage appliance in a position other than a fully seated condylar position with a flat occlusal guidance.
- Full coverage appliance in a position other than a fully seated condylar position and a directive occlusal guidance (Fig. 1, right, described in Dr. Rouse's article here).
- Posterior pivot.
- Full coverage soft appliance.
The key to mastering occlusal appliances in clinical practice is understanding why the appliance is being used. The specific appliance design selection and the fabrication method for the selected design are both determined based on the answer to this “why” question.
Occlusal Appliance Fabrication
Once the design of the occlusal appliance has been selected, the clinician begins collecting the clinical information necessary for the technician to complete the occlusal appliance fabrication.
Critical Information Includes:
- Casts or impression of the teeth (working and opposing) are necessary for both the intaglio and the cameo surface of the desired occlusal appliance.
- Relationship between the condyles and the teeth to position the maxillary arch in an anatomically correct position relative to the TM joints. This allows the technician to evaluate tooth-to-tooth and tooth-appliance relationships in excursive movements.
- Relationship between the upper and lower jaws; the jaw relationship record allows the technician to articulate the lower cast or model against the opposing arch.
Increasingly, clinicians and technicians are looking to digital workflows to maximize efficiency in all indirect restorations, prostheses, guides, and appliances. In this article, we are focusing on analog fabrications. Still, it should be noted that regardless of whether you use an analog or digital approach, the critical pieces of information required for the occlusal appliance fabrication remain the same.
Clinical Example with Analog Fabrication
A middle-aged male (Fig. 3) presented specifically for treatment limited to a night guard. The patient had been made aware of significant tooth wear by his previous clinician. The patient had no other complaints regarding his oral health. His systemic health was otherwise noncontributory, and he refused evaluation for additional airway screening or intervention. After successfully inserting the night guard, the patient anticipated returning to his previous dentist.
Upon clinical examination and review of the patient's history, muscles and joints were determined to fall within normal limits. The patient's dentition demonstrated generalized attrition. To meet the patient's objectives, a protective appliance was selected, using a full coverage flat occlusal guidance appliance in a fully seated condylar position, otherwise referred to as centric relation.
Fabricating the occlusal appliance in centric relation allows the technician to evaluate and adjust occlusal contacts in the new maximum intercuspation (at an increased occlusal vertical dimension) and manage tooth to appliance contacts that occur during mandibular movements. Fabricating an appliance of this type can be done with less sophisticated articulation. Still, the tradeoff usually involves an increase in time required for occlusal adjustments at the time of insertion.
For the dental technician to proceed with occlusal appliance fabrication using an analog approach, impressions were made clinically in the usual fashion, along with a facebow (Fig. 4: SAM 3, Great Lakes Dental Technologies) to orient the maxillary cast in a semi-adjustable articulator (SAM 3, Great Lakes Dental Technologies).
Finally, an occlusal record was made in centric relation at a vertical dimension sufficiently increased to allow a minimum of 2 mm of clearance for the desired full coverage appliance (Fig. 5).
Several options exist for making this type of record. Still, regardless of which option you select, the key is making the record at the vertical dimension that the appliance will be fabricated at. Any increase or decrease to the occlusal vertical dimension on the articulator risks introducing increased inaccuracy or error into the case, requiring an increased need for occlusal adjustment at the time of insertion.
In this case, a prefabricated Lucia jig (Lucia Jig Kit, Great Lakes Dental Technologies) relined with silicone bite registration (ACU-flow Bite Registration Kit, Great Lakes Dental Technologies) increased the occlusal vertical dimension adequately. The bite registration was made using the same silicone registration material.
With all the required clinical information collected, the case is ready for transfer to the dental technician.
Four Options for Transferring Analog Information to the Dental Technician
When fabricating an occlusal appliance, several options exist for transferring analog clinical information to the dental technician (Fig 6 – 12). We are going to look at four main options here. Regardless of the approach selected, the goal is the return of the desired occlusal appliance (Fig. 13) to the clinical office with the minimum need for occlusal adjustments (Fig. 14 and 15).
Option 1 (Fig. 6) requires the least amount of in-office preparation time. Rather than pouring the impressions and fabricating stone casts, the impressions are sent along with the additional necessary clinical information: facebow, transfer jig (SAM 3, Great Lakes Dental Technologies), and silicone bite records. It should be noted that this approach requires the use of stable impression material, such as polyvinylsiloxane rather than alginate, to maintain dimensional accuracy during transfer.
Option 2 (Fig. 7) is the minimal approach if alginate impression material is to be used and the technician cannot pour the impressions within the limited time frame of the alginate. This approach does require additional time in the office compared to Option 1. Still, many clinicians will delegate the impression-making to a trained staff member, and often alginate is a more accessible impression material for that person to use independently. It is important to note that the accuracy of these casts will impact the fit of the desired occlusal appliance to the teeth.
Option 3 (Figs. 8 and 9) again requires the casts to be fabricated in the office — and then proceeds to take the articulation a step further by attaching the maxillary cast to the articulator. This approach requires additional time and expertise if a trained staff member will be performing this step but presents the advantage of not requiring the facebow or transfer jig to be sent to the dental technician, thereby minimizing the number of face bows and transfer jigs that a busy office would require.
Option 4 (Figs. 10-12) is the most time- and labor-intensive approach to transferring the required information to the dental technician. In this approach, both the upper and lower cast are attached to the desired articulator. While this is time-consuming for the clinical team, it provides a careful analysis of the patient's existing occlusion. This is also the approach the clinical team would select if the appliance were to be fabricated in the office rather than transferred to a dental technician.
Finally, we reach the moment the clinical team and patient have been waiting for — the delivery and seating of the appliance (Figs. 13-15).
With occlusal appliances being so common in a restorative practice, small improvements in predictability and efficiency can add up to large savings over a year. While it may seem labor intensive to articulate casts with each occlusal appliance fabrication, the payoff for that time and effort comes at the time of insertion, in the form of minimal need for occlusal adjustment.
Darin Dichter, D.M.D., is a member of Spear Resident Faculty.
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November 10th, 2022