Simultaneous Intrusion and Distalization Using Miniscrews in the Maxillary Tuberosity

VICENTE JAVIER SADA GARRALDA, DDS, MSD

ini-implants can be used to manage severe results, including such demanding movements as Mdental crowding without extractions and to intrusion and arch expansion or narrowing.11-13 correct minor jaw malpositions without ortho- In an open-bite case with a mild skeletal gnathic surgery,1-4 eliminating the need for extra- Class II pattern and excessive lower facial height, oral anchorage and patient cooperation. Intruding traction from both upper and lower mini-implants the posterior segments to correct an open bite by can improve the efficiency of orthodontic treat- mandibular autorotation—traditionally difficult to ment. Another possibility is to use simultaneous achieve without extruding the incisors—is now traction from the maxillary tuberosity and the possible with skeletal anchorage. maxillary anterior region to intrude and distalize In this method of treatment, if miniscrews the upper teeth, as described in this article. are placed in interradicular spaces, the buccal teeth cannot be distalized because the implants will act Placement Procedure as stops. If they are placed in the palate, a device can be used to generate intrusive or distalizing When a mini-implant is placed in the maxil- forces on the posterior teeth without interference lary tuberosity, any lack of primary stability will from the mini-implants,5-7 but there are other dis- require relocation of the implant to an area with advantages: the risk of perforating the nasal cav- better bone. A handpiece that measures the inser- ity, the skill required to design such a complex tion torquing force is helpful in determining the force system, and the limitation of treatment to the primary retention strength of the implant. A torqu- maxillary arch. ing force greater than 5Ncm is required for im- Concomitant intrusion and distalization of mediate loading. A force greater than 10Ncm will upper and lower molars is possible by placing mini- result in bone microtrauma due to excessive com- implants in the maxillary tuberosity and the retro- pression; although this is an uncommon occur- molar region of the mandible.8-10 Although these rence in the tuberosity, it will cause a loss of sur- areas are not ideal because of poor bone quality, rounding bone and consequent implant failure.14 If they are appropriate for en-masse movement with- the torquing force is less than 5Ncm, the implant out dental interference. Proper placement protocols should demonstrate stability for at least a month and biomechanical design can lead to outstanding before it is loaded with light orthodontic forces (about 150Ncm).15-17 To produce arch expansion or contraction in addition to distalization and intrusion, lingual traction can be applied from the mini-implants in the maxillary tuberosities to lingual attachments on the teeth. To compensate for the side effects of traction, buccal attachments should be added to Dr. Sada Garralda is an Associate the posterior teeth so they can be pulled from ei- Professor in the master’s program, Department of Orthodontics, University ther side as needed. Arch expansion is generated of Valencia, Spain, and in the private by activating the lingual chain more than the buc- practice of orthodontics at San Fermín 26 Bajo, 31003 Pamplona, Navarra, cal chain, or molar compression by activating the Spain; e-mail: [email protected]. buccal chain more than the lingual chain.

Fig. 1 25-year-old female patient with skeletal Class II pattern, excessive overjet, and anterior open bite before treatment.

606 JCO/OCTOBER 2016 Sada Garralda

Case Report ment in the maxillary tuberosities and for subse- A 25-year-old female patient presented with quent distalization. The extractions were per- a skeletal Class II pattern, Class II molar and ca- formed six months prior to mini-implant placement nine relationships (complete on the left and edge- to ensure primary stability. to-edge on the right), excessive overjet, and a nar- Two Dual-Top* JA standard mini-implants row maxilla (Fig. 1). Her mouthbreathing habit had (1.6mm × 10mm) were placed distal to the second caused gingivitis of the upper incisors, and her molars in the maxillary tuberosities (Fig. 2). One vertical mandibular plane had led to lip incompe- and a half months later, since the patient wanted tence that made it difficult to close her lips at rest. to be treated with invisible appliances, the Incog- She displayed an open bite from premolar to pre- nito** lingual system was bonded and an .014" molar, a crossbite on the left side, and moderate nickel titanium archwire was inserted (Fig. 3). crowding of the upper and lower anterior teeth. This appliance is compatible with skeletal anchor- The upper and lower occlusal planes were tilted age and has proven reliable in complex treatments. from left to right, causing the mandible to show a Gentle force was applied with elastic chain from slight deviation to the left. The upper third molars the miniscrews to distalize the upper teeth. To were present, but the lower right had been extract- prevent undesirable transverse movement of the ed and the lower left was mesially impacted. molars, tubes or brackets were bonded to the buc- Traditionally, an anterior open bite and ex- cal surfaces of the first and second molars and cessive lower facial height require orthognathic connected by sectional .016" × .022" nickel tita- surgery to impact the posterior maxilla, allowing nium wires. mandibular autorotation until the anterior teeth In less than a year of treatment, the anterior contact and thereby resolving the skeletal Class II open bite was closed and the molar Class II maloc- pattern. Because this patient refused surgery, the clusion improved, but a posterior open bite had treatment plan was to use miniscrews in the max- been created (Fig. 4A). Comparing the initial pan- illary tuberosities to distalize the upper dentition. Considering the absence or impaction of the lower third molars, the upper third molars were extracted, providing space for miniscrew place-

*Jeil Medical Corporation, Seoul, Korea; www.jeilmed.co.kr. Also distributed by Rocky Mountain Orthodontics, Denver, CO; www. rmortho.com. **Trademark of 3M Unitek, Monrovia, CA; www.3Munitek.com.

Fig. 3 One and a half months later, Incognito** lingual bracket system bonded, .014" nickel titanium archwire inserted, and gentle forces applied with power chain from miniscrews to distalize upper teeth. Tubes or brackets bonded to buccal Fig. 2 Six months after extraction of upper third surfaces of first and second molars and sectional molars, one Dual-Top* mini-implant placed in .016" × .022" nickel titanium wires placed to pre- each maxillary tuberosity. vent undesirable transverse movement.

VOLUME L NUMBER 10 607 Simultaneous Intrusion and Distalization Using Miniscrews

oramic x-ray and a progress x-ray taken at that edge-to-edge bite had been corrected by applying time, there was a considerable reduction in the a bit more force from the lingual side, allowing distance between the upper second molars and the expansion of the maxillary teeth to resolve the mini-implants, demonstrating a bodily maxillary anteroposterior and transverse problems. As retraction. The posterior left crossbite and right planned, there was a substantial amount of poste-

A B Fig. 4 After 10 months of distalization. A. Distance between miniscrews and second molars reduced sub- stantially and Class II malocclusion improved, but posterior open bite created due to direction of forces. B. Power chain passed buccally over molar tubes to help control bodily movement and prevent undesirable vertical movement.

A B Fig. 5 A. Six months later, cephalometric superimposition demonstrates extrusion of upper incisors and slight autorotation of mandible. B. Gummy smile more noticeable on right side due to canted maxilla.

608 JCO/OCTOBER 2016 Sada Garralda

Fig. 6 After 16 months of treatment, two Dual-Top mini- implants placed between roots of upper lateral incisors and canines, composite buttons bonded to labial surfaces of canines, and power chain applied from miniscrews to buttons.

rior intrusion. This changed the open bite from anterior to posterior; in other words, the divergence between the upper and lower occlusal planes had shifted to a convergence of planes. Because the distalization force was applied from the mini- implant in the tuberosity to the bracket at the crown level, distal crown tipping was inevitable. Bodily movement was achieved by passing the buccal chain over the molar tubes, creating a downward force, and by increasing the size of the lingual archwire (Fig. 4B). Incognito has an ad- Fig. 7 Seven months later, greater intrusive force applied on right side to eliminate canting vantage in this respect because it uses a ribbon of maxilla. arch instead of an edgewise wire. Additionally, because the archwire has a large vertical cross- section, it compensates for the tipping effect by filling the bracket slot. 6mm) were inserted between the upper lateral Six months later, this change in biomechan- incisors and canines (Fig. 6). Composite buttons ics had resulted in anterior extrusion, which inhib- were bonded to the labial surfaces of the canines, ited autorotation of the mandible and exacerbated and power chain was attached from the mini- the gummy smile (Fig. 5). The maxillary cant screws to the buttons. Simultaneous traction was became more noticeable because the gingiva was applied to the four implants to intrude both the more visible on the right side than on the left. anterior and posterior maxillary dentition. After Anterior and posterior intrusion was re- seven months of intrusion on both sides, traction quired to reduce the gummy smile and make the was applied only to the right implants, especially upper and lower occlusal planes parallel, thus the anterior one, to further intrude the incisors allowing more mandibular autorotation. Two on that side while eliminating the maxillary cant Dual-Top JA standard mini-implants (1.4mm × (Fig. 7). The elastic chain was changed less often

VOLUME L NUMBER 10 609 Simultaneous Intrusion and Distalization Using Miniscrews

Fig. 8 A. Patient after 31 months of treatment. B. Superimposition of pre- and post-treatment cephalometric tracings.

610 JCO/OCTOBER 2016 Sada Garralda

Fig. 9 Patient two years after treatment. to maintain movement as long as possible and Discussion prevent relapse.18 Orthodontic treatment was completed in 31 When an open-bite case with a skeletal Class months, with the open bite closed and the incisor II pattern is treated using skeletal anchorage from overlapping corrected. A canine and molar Class palatal mini-implants, the intrusion must be car- I relationship and normal function were achieved, ried out before the distalization, thereby prolong- with anterior and canine guidance (Fig. 8A). The ing treatment. An alternative would be to place treatment approach described here resolved the both palatal and buccal mini-implants to achieve skeletal Class II pattern while intruding the pos- a neutral effect, allowing intrusion and distaliza- terior segments, allowing mandibular autorotation. tion to occur without the teeth tipping buccally or 3 Anterior intrusion during the second half of treat- lingually. The buccal implants can block distal ment improved the patient’s facial appearance by movement, however, unless they are placed paral- achieving parallelism of the upper and lower oc- lel to the roots, which is not always possible. Four clusal planes and eliminating the gummy smile. implants are also needed, which increases the risks Counterclockwise rotation of the mandible then of insertion (particularly in the palate), as well as reduced the lower facial height and increased the the cost and duration of treatment. chin prominence, resulting in a more esthetic pro- By contrast, skeletal anchorage from the file. Long-term stability was enhanced by the maxillary tuberosity requires only one mini- achievement of functional harmony among the implant on each side and does not interfere with orofacial muscles. The patient could close her lips distal tooth movement. Therefore, this is the ideal without straining the mentalis muscle, and her method in cases requiring simultaneous intrusion open-mouth posture, which had caused mouth- and distalization. breathing and a lower tongue placement, was al- Intrusive forces applied to the upper poste- leviated. rior teeth generate a clockwise movement and a Superimposition of pre- and post-treatment consequent counterclockwise mandibular rotation, cephalometric tracings confirmed the intrusion of so that minor changes in the upper posterior teeth the upper molars, along with slight retroclination can produce remarkable effects in the lower ante- and extrusion of the upper incisors (Fig. 8B). The rior region. Only 1mm of upper-molar intrusion mandibular plane angle was reduced from 28.8° can reportedly displace the chin up and forward to 28.0° with respect to the Frankfort plane. The by 3-4mm.19 In the case shown here, that effect was ANB angle decreased from 7.0° to 5.4°. Conse- restricted by extrusion of the upper incisors. Be- quently, there was a shift from the obvious skeletal cause mandibular autorotation is limited by contact Class II pattern to a skeletal Class I. between the upper and lower anterior teeth, the Results remained stable two years after the upper-incisor extrusion had to be controlled with completion of treatment (Fig. 9). anchorage from two anterior mini-implants. On

VOLUME L NUMBER 10 611 Simultaneous Intrusion and Distalization Using Miniscrews

the other hand, excessive intrusion of the upper posttreatment, Am. J. Orthod. 141:484-494, 2012. 3. Park, H.S.; Kwon, O.W.; and Sung, J.H.: Nonextraction treat- incisors should be avoided to ensure an esthetic ment of an open bite with microscrew implant anchorage, smile line. Am. J. Orthod. 130:391-402, 2006. Mini-implant placement in the maxillary 4. Tamamura, N.; Kuroda, S.; Sugawara, Y.; Takano-Yamamoto, T.; and Yamashiro, T.: Use of palatal miniscrew anchorage tuberosity requires careful consideration of a num- and lingual multi-bracket appliances to enhance efficiency of ber of variables—including primary stability, load- molar scissors-bite correction, Angle Orthod. 79:577-584, ing, and applied force—due to the poor quality of 2009. 5. Wilmes, B. and Drescher, D.: Applications and effectiveness bone. Although our patient’s treatment time of 31 of the Beneslider: A device to move molars distally, World J. months was longer than that of an average ortho- Orthod. 11:331-340, 2010. dontic case, the lack of an established protocol for 6. Wilmes, B.; Nienkemper, M.; Ludwig, B.; Nanda, R.; and Drescher, D.: Upper-molar intrusion using anterior palatal an- this technique required corrections to problems chorage and the Mousetrap appliance, J. Clin. Orthod. 47:314- encountered as treatment progressed. After man- 320, 2013. aging several similar cases, we developed a regi- 7. Ludwig, B.; Blasl, B.; Bowman, S.J.; Wilmes, B.; Kinzinger, G.S.; and Lisson, J.A.: Anatomical guidelines for miniscrew men that allowed us to achieve the same effects in insertion: Palatal sites, J. Clin. Orthod. 45:433-441, 2011. less time. 8. Lee, S.P.; Paik, K.S.; and Kim, M.K.: Study of the pyramidal process of the palatine bone in relation to implant placement in the posterior maxilla, J. Oral Rehab. 28:125-132, 2001. Conclusion 9. Graves, S.L.: The pterygoid plate implant: A solution for re- storing the posterior maxilla, Int. J. Period. Restor. Dent. The maxillary tuberosity offers many clini- 14:512-523, 1994. 10. Rodrígues, X.; Rambla, F.; De Marcos Lopez, L.; Méndez, V.; cal advantages compared to other mini-implant Vela, X.; and Jiménez Garcia, J.: Anatomical study of the insertion sites. Problems can be addressed simul- pterygomaxillary area for implant placement: Cone beam taneously in all three planes of space. Maxillary computed tomographic scanning in 100 patients, Int. J. Oral Maxillofac. Implants 29:1049-1052, 2014. teeth can be distalized without interfering with 11. Venkateswaran, S.; Rao, V.; and Krishnaswamy, N.R.: En- their roots. Both anterior and posterior teeth can masse retraction using skeletal anchorage in the tuberosity be intruded when mini-implants are added in the and retromolar regions, J. Clin. Orthod. 45:268-273, 2011. 12. Anhoury, P.S.: Retromolar miniscrew implants for Class III anterior maxilla. Transverse movement can be camouflage treatment, J. Clin. Orthod. 14:706-715, 2013. controlled with traction from either the buccal or 13. Marinetti, A.; Deffrennes, D.; and Soussan, J.: Presurgical lingual side, which is ideal in an open-bite case preparation for mandibular advancement with retromolar skeletal anchorage, J. Clin. Orthod. 47:529-536, 2013. and works well in a skeletal Class II case with 14. Wawrzinek, C.; Sommer, T.; and Fischer-Brandies, H.: extruded upper teeth and an extremely vertical Microdamage in cortical bone due to the overtightening of mandibular plane. Mandibular autorotation can orthodontic microscrews, J. Orofac. Orthop. 69:121-134, 2008. also be achieved. 15. Wilmes, B. and Drescher, D.: Impact of insertion depth and This technique is a good alternative to ortho- predrilling diameter on primary stability of orthodontic mini- gnathic surgery, without the potential complica- implants, Angle Orthod. 79:609-614, 2009. 16. Büchter, A.; Wiechmann, D.; Gaertner, C.; Hendrik, M.; tions. Fewer mini-implants are needed compared Vogeler, M.; Wiesmann, H.P.; Piffko, J.; and Meyer, U.: to other systems, and no laboratory work is re- Load-related bone modelling at the interface of orthodontic quired. More research is needed to establish pro- micro-implants, Clin. Oral Implants Res. 17:714-722, 2006. 17. Motoyoshi, M.; Hirabayashi, M.; Uemura, M.; and Shimizu, tocols for all possible combinations of mini- N.: Recommended placement torque when tightening an implants used to treat skeletal problems. orthodontic mini-implant, Clin. Oral Implants Res. 17:109- 114, 2006. REFERENCES 18. Sugawara, J.; Baik, U.B.; Umemori, M.; Takahashi, I.; Nagasaka, H.; Kawamura, H.; and Mitani, H.: Treatment and posttreatment dentoalveolar changes following intrusion of 1. Park, Y.C.; Lee, S.Y.; Kim, D.H.; and Jee, S.H.: Intrusion of mandibular molars with application of a skeletal anchorage posterior teeth using mini-screw implants, Am. J. Orthod. system (SAS) for open bite correction, Int. J. Adult Orthod. 123:690-694, 2003. Orthog. Surg. 17:243-253, 2002. 2. Chung, K.R.; Jeong, D.M.; Kim, S.H.; Ko, Y.I.; and Nelson, 19. Kuhn, R.J.: Control of anterior vertical dimension and proper G.: En-masse retraction dependent on a temporary skeletal selection of extraoral anchorage, Angle Orthod. 38:340-349, anchorage device without posterior bonding or banding in an 1968. adult with severe bidentoalveolar protrusion: Seven years

612 JCO/OCTOBER 2016