deep and the skeletal vertical is not open and the patient is not an extreme clockwise grower (Fig 52). í Use retraction 2x4 archwires if the torque on the incisors is excessive. Use transpalatal arches to hold the molars to keep them from advancing (Fig. 18). í Consider converting incisors that present with either excessive or insuf-ficient torque to close to a normal torque before intruding them (espe-cially extremely flared incisors). Excessive retraction of flared incisors before intrusion may lead to a situa-tion where the roots now engage the labial plate making intrusion not possible and leading to root resorption (Fig. 53) 5 . í Use expansion 2x4 archwires if the torque on the incisors is insufficient (Fig. 35-B). í Skip archwires if you accomplish all of your intended goals with one archwire (e.g., the .018 Nitanium Adjustable Utility Archwire-NUA). There is no need to use other 2x4 archwires. At this point proceed to a full appliance (bracket and band the remaining teeth). In a clockwise grower or open skeletal vertical dimension cases (Fig. 52) how does the practitioner control the skeletal vertical? í Light intrusive forces (10-15 grams per incisor) can make the reactive forces on the anchor teeth (molars) well below the force levels needed for their extrusion and distal tipping while intruding the incisors. 11 The forces of mastication also help to rein in unwanted molar extrusion. 13 í Increase the number of teeth in the anchor unit. One method is to extend the wire ends through both molar brackets on each side (Fig. 54-A). Another method is to use a sectional wire connecting the molars and bicus-pids (Fig. 54-B). If this method is employed the intrusion archwire will be placed into Divincenzo inserts that have been inserted into the headgear tubes (Fig. 19). í Use a transpalatal arch (TPA) that is somewhat flat across the arch (Fig. 55). When the patient swallows the 38 Summer 2015 JAOS tongue engages the TPA placing an intrusion force on the molars. í Use a lip bumper in either the maxil-lary or mandibular arches. 5 If a clini-cian is utilizing a lip bumper to develop an arch it may be adapted in order to intrude incisors. In the lip bumper cases that I treat that need incisor intrusion, I solder onto the lip bumper bilateral 6mm vertical exten-sions with the hooks facing to the distal (Fig. 56-A and B). A power chain is tied on one hook, connected to the cuspid, incisors, and opposite cuspid, and then extended to the other hook (Fig. 56-C). The force levels required for intrusion will determine how many links are present from the hooks to the cuspids. In the case shown the patient’s mandibular incisors are proclined and need retraction and intrusion. The custom hooks on the lip bumper are placed distal-gingival to the COR of the anterior teeth so that retraction may occur as the teeth are being intruded (Fig. 57). Depending on whether the incisors need retraction while intruding, intrusion only, or labial advancement while intruding determines the location of where the hooks will be soldered onto the lip bumper (Fig. 58). í Use a high-pull headgear to prevent molar extrusion when intruding incisors. 10 í Use TAD’s, in two different ways: 1) To hold the molars to keep them from erupting when intruding incisors with an activated 2x4 appliance (Fig. 59-A and B). And, 2) use TADs directly to intrude the incisors. Attach a power chain (Fig. 60-A) or a NiTi closed coil spring (Cope ATADchments) (Fig. 60-B) from a TAD directly to a tooth (teeth) or an archwire. Cope recommends an intrusive force of 40 grams per side. Part 2 in the discussion of developing proper overbite and overjet will appear in the next issue of the JAOS. Clinical cases will be shown demonstrating the concepts discussed in this article. Successful Results Dr. Ravindra Nanda states, “There are many methods to correct deep overbite malocclusions. Successful results have been obtained with many techniques.” 9 To paraphrase, there are many methods to obtain proper overbite and overjet. In this article I have illustrated (Figs. 38-51) the wires and techniques I utilize in my practice. Other practitioners may utilize fewer archwires than those shown to achieve the intended results called for in a case. Based on a proper diagnosis, select the technique that will best correct the patient’s malocclusion. The 2x4 appliance with tip-back bends placed mesial to the maxillary first molar brack-ets, the piggy back intrusion arch, a custom fabricated lip bumper, and TAD aided incisor intrusion methods are effective tools for align-ing, intruding, retracting, protracting, and torquing incisors in cases that call for it. Ortho-pedic advancement of the mandible is effective in skeletal and dental deep bite cases when the maxillary and mandibular incisors present with normal torque. 4 There are important concepts to consider when employing the various incisor move-ment mechanics to achieve a proper overbite and overjet: í Use a round (not a rectangular) wire when intruding incisors with a 2x4 appliance (Figs. 22-23). í Do not place a 2x4 intrusion archwire into the cuspid brackets (Fig. 26). í Consider converting incisors that present with extremely excessive torque to close to a normal torque range before intruding them (Fig. 53). í In young patients properly executed Mulligan vertical mechanics allows for simultaneous incisor alignment, intru-sion, retraction or protraction, proper torque, arch length gain, and Class II correction (Fig.10-12). í In patients whose second molars have erupted the molars should be distalized and the arches widened if necessary before incisor intrusion and retraction mechanics are used (Fig. 13). í Assess the patient’s tooth display in a full smile before deciding which incisors (maxillary, mandibular, or both) to intrude (Fig. 14). í Assess the patient’s existing skeletal vertical dimension (Fig. 52). í Assess the patient’s growth direction: neutral, clockwise, or counterclock-wise (Fig. 52). Editor’s Note: For a full list of references, visit www.orthdontics.com
Journal of the American Orthodontic Society Summer 2015-Buyer's Guide: Page 38
