Dr. Boyd's "Preferred Pack"
(a message from James Boyd, DDS, developer of the NTI Therapeutic Protocol)
As my insight and understanding of nocturnal parafunction has continued to evolve, so has my practice of the use of NTI devices. When it comes to their use, I am often simply asked, by new users and experienced providers alike, "Which devices do you use, and why?"
NTI devices are simply a method to achieve a therapeutic goal in an efficient amount of time. The therapeutic goal has always remained to: 1) Minimize muscle contraction intensity, which is accomplished by preventing canine and molar contact during parafunction (thereby obligating incisor contact, only); 2) Minimized joint strain and load during the parafunctional events, which is accomplished by minimizing the degree of condylar rotation during parafunctional events, and that is accomplished by minimizing the vertical dimension.
All NTI devices are designed to prevent canine and posterior occluding, so the next consideration is minimizing the degree of Vertical Dimension, that is, minimizing the degree of condylar rotation during the parafunctional event. (Delivery Flow Sheet)
Generally speaking, the degree of incisal overlap dictates which device, either maxillary or mandibular, is used. When incisal overlap is excessive, a maxillary device ("Upper") is used with the Discluding Element being shaved by the practitioner to "ramp" up towards the palate to keep VDO minimal. On the other hand, when incisal overlap is minimal (or non-existant), a mandibular ("Lower") device is used. (In the event of extreme excursive movement, my "default" choice is the Lower device. If an Upper is used, there is the likelihood that a lower canine may engage the Discluding Element).
In addition to the two primary objectives of NTI protocol (minimal muscle contraction intensity and minimal joint strain/load), there is still one more critical aspect in obtaining maximum clinical success, and that is the provision of minimal lateral resistance and contact at the interface of the Discluding Element.
Often times, one (or more) of the incisors that oppose the Discluding Element is not "ideal" (i.e., rotated, elevated, tilted, etc), making the contact of the opposing incisors on the Discluding Element, especially during excursive movements, disruptive. For example, although two central incisors may be contacting the Discluding Element equally and comfortably, the incisal edge corner of an elevated lateral incisor may dig and grind into the Discluding Element, producing considerable resistance to lateral movement and strain on a joint complex as a Lateral Pterygoid isometrically pulls on the condyle. Although this may not be problematic for the patient with mild to moderate symptoms, it can be a significant-enough source of nociception to prevent the maximum beneficial outcome for the migraine sufferer, as the goal in reducing migraine frequency and intensity is to minimize nocioceptive input to the trigeminal sensory nucleus.
The traditional remedy (or prevention) has been to "adjust" the Discluding Element's shape and contour, or to alter the opposing irregular incisal edge(s) in order to achieve smooth, unresisted movements of the incisors across the Discluding Element.
Physical alterations of the Discluding Element and/or the opposing incisors has its considerable drawbacks, but there is a superior alternative. By providing for an "Auxiliary Slider" on the opposing incisors, all of the critical necessities for clinical success can be met. An Auxiliary Slider is any smooth and continuous surface over the opposing incisor's edges, that interfaces against the Discluding Element. Contrary to the misunderstanding that an NTI device exploits the "opening reflex" during sleep (there is no such thing), the use of an Auxiliary Slider over the opposing incisors continues to maintain the absence of posterior and canine contact (which is the actual method of minimizing muscle contraction intensity). However, the provision of an Auxiliary Slider can increase the VDO, so it is the practitioner's obligation to confirm that the VDO is not excessive, and may need to reduce the height of the opposing Discluding Element (this is done by instructing the patient to clench intensely on the devices(s) to confirm absence of joint pain. VDO of the DE is reduced until clenching does not illicit pain).
A custom Auxiliary Slider can be produced by making a .06" plastic suckdown over a model of the opposing incisors (and then the incisal irregularities filled in with ortho acrylic), or an NTI Auxiliary Slider Device (sometimes referred to as the Daytime Device) can be delivered (usually simultaneously with delivering the NTI device).
The Auxiliary Slider device does require slight modification prior to its delivery. The incisal occluding surface of the Auxiliary Slider is flat from end to end. In order to obtain a point contact during parafunctional occluding, the ends of the occlusal surface should be tapered to a thin edge, resulting in the midpoint of the Auxiliary Slider being slightly thicker than the ends. This can be easily and quickly performed prior to delivery.
With the implementation of opposing devices, the list of variables to overcome becomes much shorter, in fact, it simplifies the standard NTI protocol. The more I began to provide an opposing Auxiliary Slider, the more it became part of my standard delivery protocol and I now provide an opposing Auxiliary Slider routinely. In fact, my current standard protocol is to provide two opposing Auxiliary Sliders! When the mandible is in its retruded position, the incisal edge of the Lower Slider is occluding on the DE of the Upper Slider. When the mandible is in a protruded position, the Upper Slider's incisal edge is occluding on the DE of the Lower Slider. What has turned out to be the biggest benefit is the absence of a DE that extends labially, so there is nothing impinging into the patient's lip, thereby enhancing patient comfort and compliance.
Implementation of two Auxiliary Sliders still obligates the practitioner to confirm that the opposing devices creates a point contact (the surfaces of both devices should be altered prior to delivery), and that VDO is minimized (both DE's can be ramped and confirmed at try-in).
Auxiliary Sliders have always been available as a stand-alone product, thereby including glow-in-the-dark boxes and thermoplastic beads (which would be unnecessary to purchase if combining an Auxiliary Slider with an opposing NTI device).
Therefore, ChairsideSplintStore.com now has a new selection of “NTI Preferred Packs”, which include the traditional pack of NTI devices and an equal number of Auxiliary Sliders, at a price less than buying two separate packs of devices.