TAD Influence by Drs. Trevor Nichols and Stuart Frost

Some of the ways anchorage can help treat patients faster

by Drs. Trevor Nichols and Stuart Frost

The profession of orthodontics is evolving, which means orthodontists must create solutions that offer patients a variety of treatment options. And with today’s competitive challenges to our profession, incorporating and offering new treatment methods can also elevate ourselves and our practices.

As specialists in orthodontics and craniofacial orthopedics, we need to remember that every treatment plan should consider an orthodontic component as well as an orthopedic one, even in nongrowing patients. Orthopedic, by definition, means “the correction of deformities of bones or muscles.” Historically, such deformities have been treated successfully among young patients, but in adults have traditionally been treated by surgery alone. With the advent of temporary anchorage devices (TADs), orthopedic correction can be accomplished even in nongrowing patients.

TADs were introduced more than 35 years ago, but in a 2008 survey, Buschang et al. determined that more than half of the members of the American Association of Orthodontists had placed 10 or fewer TADs, and most orthodontists had referred the placement to other specialists.¹

TAD placement in the orthodontic practice

For those new to TADs or considering their use in practice, this workflow for TAD placement is repeatable and simple.

Step 1: Determine location. Clearly, TAD placement will be determined in part by the mechanics they’re used for. In addition to the mechanics used for TAD anchorage, there are important factors to individual anatomy that should be considered.

First, a recent cone-beam computed tomography (CBCT) or pano should be obtained. This radiograph can be used to evaluate root divergence, bone height and, to some extent, bone density. Fig. 1 highlights two areas indicated by arrows. The red arrow indicates a radiolucent area indicative of lower bone density, where TAD placement would not be suggested. In contrast, the blue arrow indicates a radiopaque area, which suggests one with better bone density that would be more ideal for TAD placement.

Step 2: Consider anesthesia options. In our practice, most patients prefer local anesthesia (injection) for TAD placement to ensure that they’re comfortable during the procedure. For these cases, 2% lidocaine HCL with 1:100,000 epi is used via local administration directly into the vestibule adjacent to the desired TAD location. Typically, one-fourth of a cartridge provides adequate anesthesia. If the patient declines local anesthesia, another option is to place a topical compound directly on the tissue. (See Fig. 2.)

Step 3: Tissue evaluation. Once the site has been located and the patient sufficiently anesthetized, perform a clinical assessment of the hard and soft tissues. Use a Hu-Friedy PKT2 waxing instrument (Fig. 3) first to verify anesthesia, then to make a vertical depression to mark the intraradicular space. Next, select the deepest area in the attached tissue approximately 1mm occlusally from the mucogingival junction (but not into the free mucosa). Using the vertical line and soft tissue location, use the waxing instrument to evaluate bone quality by pressing into the tissue and bone. If the bone feels solid, site is selected; if the waxing instrument sinks into the bone, another location along the intraradicular line should be selected.

Step 4: TAD selection. Once the site is located, select the appropriate TAD. We use the Vector system from Ormco, including 1.6-by-6mm devices in the anterior, 1.6-by-8mm in the posterior and 1.6-by-10mm for the palate. For buccal shelf, ramal and infrazygomatic TAD placement, we use 2-by-12mm stainless steel bone screws from Ortho Bone Screw.

Step 5: Placement. TADs are placed using either an electronic driver or a manual hand driver. (We use the Orthonia driver from Rocky Mountain Orthodontics with the Vector system.) Regardless of the method of insertion, a sturdy hand is important for TAD stability; the clinician also should feel the TAD going into the bone snugly. TADs should be placed until the tissue blanches and the TAD neck is flush with the tissue.

Step 6: Verification. After the TAD has been placed, use a plier to verify primary stability. Because a TAD does not osseointegrate, the day it’s placed is the most stable it will ever be. If primary stability is not obtained, remove and reinsert in another location, using the same TAD, the day of initial placement. Be sure to repeat Step 3 at the new site before placing any device.

When considering the mechanics of TAD utilization, the concept of anchorage can be divided into two categories:

Direct anchorage: When the miniscrew or TAD is tied to a tooth with a spring, elastic or cantilever arm.

Indirect anchorage: When a TAD is used and tied to another tooth, which is then used as anchorage.

Fig. 1: Extracted pano from iCAT CBCT, indicating poor bone quality (red arrow) and good bone quality (blue arrow).

Fig. 3: Clinically evaluating bone quality of TAD placement site.

Treating gummy smiles

One of the most common uses for TADs in our practice is to correct gummy smiles. This includes cases with absolute, posterior or anterior maxillary excess. All are treated using TADs as direct anchorage for intrusion; they vary only in location of intrusion.

EXAMPLE 1: ANTERIOR GUMMY SMILE

An anterior gummy smile is one in which a patient shows excess gingival display from upper cuspid to cuspid (Fig. 4). This is taking into account ideal crown shape and size, where the patient has true anterior maxillary excess and is not just in need of a gingivectomy or crown-lengthening procedure. Because there exists some variation in the patient smile and the patient’s willingness or ability to show a genuine smile, a gummy smile can be best diagnosed through evaluation of the upper central incisor at rest. We can capture this by asking the patient to say the word “Emma.” If the patient shows more than 75% of the upper incisor at rest, this is a good indication that the patient is in need of gummy smile treatment. (Fig. 5).

These cases are treated by placing 1.6-by-6mm TADs between the upper 2/3s. If slight posterior impaction is desired, bite turbos with triad gel can be placed on the lower 7s to be squeezed 60 times, six times per day, to impact posterior molars by engaging the posterior fibers of the temporals.

TADs are placed at the second visit, tied from the anchor to a 14x25 copper nickel titanium (CuNiTi) arch wire with an elastic (surgical) thread (Figs. 6 and 7). Once the patient has progressed to larger CuNiTi wires or stainless steel, TADs can be tied to the wire using power chain looped to the wire or NiTi closing springs (Fig. 8), depending on the thickness of the tissue.

Once the intrusion is completed, tie the TADs to the wire and use vertical elastics to close the bite without relapse of the intrusion. If buccal crown tip is visible because of the moment created by the intrusion, use a power chain torquing sling to encourage lingual crown tipping and to prevent flaring of the incisors (Fig. 9).

After the case is completed and the brackets have been removed, perform a gingivectomy to idealize the tissue shape (Figs. 10 and 11) and make final contours to the hard tissue.

EXAMPLE 2: POSTERIOR GUMMY SMILE

A posterior gummy smile is one in which there is a posterior maxillary excess and a patient displays more than 4mm of posterior gum (Figs. 14 and 15).

For these cases, 1.6-by-8mm TADs are placed between the upper 5/6s or the upper 4/5s. Bite turbos are placed on the lower 6s with triad gel to allow the lingual cusps of the upper molars to occlude with the lower posteriors, to prevent buccal flaring of posterior teeth.

The same protocol as the previous example is used, with TADs are placed at the second visit and tied to 14x25 CuNiTi arch wire using elastic thread (Figs. 16 and 17). Once the patient is in larger CuNiTi or stainless steel wires, the TADs are tied to the wire using power chain or NiTi closing springs (Figs. 18 and 19).

After the impaction is completed, the TADs are tied to the wire using steel ligature and box elastics are used to close the posterior bite. To maintain space closure, a tie-back module is used from a hook on the wire mesial to the 3 to the hook on the 6 and is placed occlusal to the brackets to prevent gingival impingement (Figs. 20 and 21).

Again, after treatment, a gingivectomy is performed to idealize tissue shape and size (Figs. 22 and 23) and hard tissue contouring is performed.

EXAMPLE 3: ABSOLUTE GUMMY SMILE

Cases that have both anterior and posterior gummy smiles (Figs. 26 and 27) combine the previously described methods, using a total of four TADs: two anterior TADs placed between the upper 2/3s and two posterior TADS between the upper 5/6s or 4/5s, with triad bite turbos on the lower 6s (Fig. 28).

In some cases, intrusion may occur asymmetrically (one side faster than another, or anterior faster than posterior). For these occurrences, when one area is completed with intrusion, the TAD is tied to the wire, and intrusion continues in others until all intrusion is completed.

Gingivectomy and hard tissue contouring is completed (Figs. 29 and 30).

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Treating missing teeth

We commonly see missing teeth, whether congenitally missing or extracted, and it’s nice to be able to offer options to patients, particular younger ones with congenitally missing posterior teeth. For many of these cases, we offer the solution of TAD placement and space closure with maximum anchorage.

For cases with missing teeth, TADs are placed anterior to the edentulous area and used as indirect anchorage by tying with a stainless steel ligature distally to the adjacent tooth. A NiTi closing spring is then used to close the space. This is a simple and effective way to maintain anchorage and close space for missing teeth.

Especially in cases with congenitally missing premolars, where the primary molar is not a long-term viable option, TADs are a great option in young patients to use as anchorage and close spaces by protraction.

EXAMPLE: MISSING PREMOLARS

The patient (Figs. 33 and 34) is bonded initially, but the retained primary teeth are not bonded. Arch wire progression is completed; once the stainless steel wire is placed, the primary teeth are extracted and TADs are placed mesial to the edentulous area and indirectly tied to use as anchorage. Extraction is held until space is ready to close to take advantage of the regional acceleratory phenomenon to aid in efficient space closure. A NiTi closing spring is then used from a post on the arch wire around the distal on the wire distal to the tooth adjacent to the edentulous area. The space is then closed (Figs. 35 and 36). A wire tie is placed to ensure space closure is maintained without continuous use of elastic chain (Figs. 37 and 38).

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Treating a deep bite correction

Correction of severe deep bites can be challenging, particularly among adult brachiocephalic individuals. For this reason, we supplement treatment with the use of TADs to aid in correction of the deep bite.

If the lower cuspid to cuspid needs intrusion, two TADs are placed and initially tied with elastic thread in light wires. Once stainless steel wires are placed, power chain is used to continue intrusion. If only lower incisors need intrusion, one TAD is placed in the midline to aid in correction.

EXAMPLE 1: DEEP BITE ADULT INTRUSION OF LOWER CUSPID TO CUSPID

In cases where the deep bite consists of over-eruption of the lower 3–3 (Figs. 39 and 40), 1.6-by-6mm TADs are placed between the lower 2/3s bilaterally to aid in opening the bite (Figs. 41 and 42).

EXAMPLE 2: DEEP BITE ADULT INTRUSION OF LOWER INCISORS

For deep bite cases in which just the lower incisors are extruded (Fig. 43), a single TAD is placed between the lower 1s (Fig. 44).

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Treating mandibular distilization

Buccal shelf TADS are a great solution for Class III patients in need of mandibular distalization for profile aesthetics and dental function (Figs. 45–48). They allow for noncompliance correction of Class III cases with decreased compensations of the upper arch.

For these cases, a 2-by-12mm Ortho Bone Screw is placed mesial to the lower 7 into the buccal shelf of the mandibular body. If a patient has 8s, they are extracted right before the TADs are placed once in the stainless steel wires.

Once the patient has progressed to stainless steel wires, buccal shelf TADs are placed. A lower pre-posted stainless steel wire is used and a Vector NiTi closing spring is placed from the buccal shelf TAD to the post (Fig. 49).

Once the Class III is corrected, a steel ligature is used to retain the Class III while finishing and detailing is completed (Figs. 50 and 51).

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Treating skeletal expansion

In cases where absolute maxillary expansion is desired with little to no dental side effects, maxillary anchorage with TADs is a wonderful solution. This allows for sutural expansion that has little to no dental compensation. Many designs exist for TAD placement with expansion.

In some cases, a tissue-born expander is used with no anchorage on the molars (Figs. 58 and 59). This is typically used to encourage the maximum amount of skeletal expansion when dental tipping is undesired.

In cases where molar anchorage is desired, a banded approach can be used in conjunction with TADs (Figs. 60–65).

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Conclusion

TADs can change much of the way orthodontists practice. We can expand the way we change lives, and affect our patients in more profound ways. TAD placement is simple and requires little clinical time. The clinical uses for temporary anchorage devices are vast. Orthodontists should become comfortable with TAD placement and mechanics, and should consider their use in various cases in clinical practice to help provide optimal treatment outcome.

References
1. Buschang, PH, Carrillo, R, Ozenbaugh, B, Rossouw, PE. 2008 Survey of AAO members on miniscrew usage.
J Clin Orthod. 2008;42:513–518.