Getting Things Back on Track by Dr. R. Bruce McFarlane

How to use clear aligners to treat deep bites, with help from MOPs and HFV

by Dr. R. Bruce McFarlane

Deep bites are tough enough to overcome with brackets and wires—and they’re even more challenging to tackle with clear aligners. Especially with our adult patients, we are very often battling well-established large overbites that are exacerbated by tooth wear, parafunction and heavy musculature.

The solution most often includes leveling the curve of Spee through a combination of incisor intrusion and premolar and molar extrusion. The teeth are resistant, so an imbalance exists between incisor roots that don’t want to intrude and larger posterior teeth that are stubborn to extrude. This results in aligners not tracking, frustration and frequent case refinements.

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Acceleration technique #1: MOPs
The challenge has been well recognized for some time, and various solutions have been introduced, including more robust lower attachments for leveling curves of Spee (Fig. 1), bite ramps on the palatal aspects of upper anterior teeth (Fig. 2), and overengineering of the overbite correction and upper incisor crown torque (Fig. 3).

Despite the improved understanding of the biomechanics of deep-bite reduction and the innovations introduced by aligner manufacturers, the struggle continues; long-standing deep bites in adults with clear aligners are still very difficult and frustrating. The two biggest issues are bone remodeling resistance and clear aligner tracking loss. The treatment tools I most often use to address those issues are micro-osteoperforation (MOPs) and high-frequency vibration (HFV)—in my cases, using products made by Propel Orthodontics.

When discussing micro-osteoperforation with patients, we describe it as “softening” the bone. This is an apt representation of what truly happens. The act of perforating the cortical and cancellous bone with a bur initiates a temporary inflammatory cascade that ultimately results in heightened osteoclast activity, and therefore accelerated and more assured tooth movement (Fig. 4). By activating the patient biology, we are able to deliver finishes quickly—as much as 2.3x faster than traditional treatment alone.

The MOPs are administered with a proprietary driver and specialized tip designed to create a field of microfractures. A “halo” around each perforation affects the bone in an area 8–10 millimeters in diameter, and the maximum activation lasts about 12 weeks—unless it’s combined with HFV, in which case the effect should last the entire length of the case. For deep-bite correction, the practitioner can time the most profound effect to the best advantage—that is, provide the perforations in advance of the 12 weeks in which the aligners are forecast to be performing the most incisor intrusion and premolar extrusion.

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Acceleration treatment #2: HFV
Tracking issues are problematic for many aligner movements, including deep bites. No matter how well the aligners are preprogrammed, if they don’t fully seat, their effect will not be expressed. Subsequent aligners will multiply the problem, and the case will go off the rails.

HFV addresses this by causing the aligner to be fully seated and to adapt as closely as possible to teeth and attachments (Fig. 5). Moreover, HFV continues the biological activation of osteoclasts and bone remodeling. When patients gently bite on the VPro Series mouthpiece for five minutes per day, its high-frequency vibration activates the biology, causing a reduction in treatment time by up to 64%, obtunds pain and ensures ultimate aligner seating. This is of utmost importance when it comes to leveling stubborn curves of Spee.

HFV enables clinicians to expand case selection with aligners. Currently, clinicians choose to treat about 45% of cases with aligners alone. Adding HFV enables me to treat more than 90% of cases effectively with aligners, and with fewer attachments. For very difficult cases, I find that MOPs and HFV have a synergistic effect, and I recommend that they be used together when battling deep bites with aligners: MOPs activate the bone biology, and HFV makes sure the aligners express most profoundly the tooth movements in the awakened bone and continue the biologic activation.

Conclusion
The addition of micro-osteoperforation and high-frequency vibration to my practices has resulted in much more predictable, profound and timely deep-bite corrections. Less-frequent aligner tracking loss and fewer case refinements have increased patient and practitioner satisfaction remarkably.

Case Studies

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Case 1
This 34-year-old aligner patient had a deep bite (Fig. 5), and several attempts to level her curve of Spee with Invisalign and Invisalign G5 innovations had failed. The decision was made to incorporate MOPs and HFV (Fig. 6).

Seventeen more aligners with HFV for five minutes each evening finally solved a most tenacious deep bite (Fig. 7).

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Case 2
This 25-year-old patient had a deep bite and wear on her lower anterior teeth, and several rounds of aligners with all of the recommended innovations had not solved the deep bite (Fig. 8).

At nine months into treatment, with aligners losing tracking again (Fig. 9), the decision was made to incorporate MOPs and HFV. Three months later, the aligners were seating (Fig. 10), and the deep-bite correction was finally mobilized.