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Complications Encountered in TemporaryOrthodontic Anchorage Device TherapyChristopher E. Roncone

Although absolute anchorage with the use of fixed skeletal implants is not

a recent concept in orthodontic mechanotherapy, its popularity in recent

years has increased exponentially as a result of the advent and widespread

manufacture of temporary anchorage devices (TADs). TADs are an invalu-

able asset to contemporary orthodontics, facilitating tooth movement that

might otherwise require (1) surgical repositioning of the jaws, (2) extraction

of permanent teeth, and/or (3) extended use of extraoral anchorage. As

more orthodontists incorporate TADs into their therapeutic regimens, the

clinician should be cognizant of the variety of iatrogenic sequelae that may

occur with the employment of such adjuncts. Complications include, but are

not limited to, encroachment upon adjacent anatomical structures, mucosal

perforations or tears, peri-implantitis, and unintended tooth movement. A

review of some common problems with clinical examples, as well as pro-

tocols for prevention is presented. (Semin Orthod 2011;17:168-179.) © 2011

Elsevier Inc. All rights reserved.

b

D uring the past several decades the disci-pline of orthodontics has benefited from

variety of innovations that have enhancedlinical practice. The preadjusted appliance,ight-cured adhesives, metallurgical hybridiza-ion of arch wires, and self-ligating bracketsre just a few examples. Although each ofhese technologies has readily integrated intooutine practice, the placement and use ofaxillomandibular bone anchors— orthodon-

ics’ most recent clinical adjunct— has provenore elusive in this regard. This is attribut-

ble, perhaps, to the fact that placement ofuch fixtures has long been the purview of oralurgeons or periodontists; those who have re-eived surgical training in their residency pro-rams. The most contemporary incarnation ofkeletal anchorage, however—the temporary an-horage device, or TAD—has evolved such thatlacement by orthodontists is not only feasible

Private Practice, Temecula, CA.Address correspondence to Christopher E. Roncone, DDS, MS,

32140 Temecula Parkway, Ste 201, Temecula, CA 92592. E-mail:chris@ronconeortho.com

© 2011 Elsevier Inc. All rights reserved.1073-8746/11/1702-0$30.00/0

doi:10.1053/j.sodo.2011.01.003

168 Seminars in Orthodontics, Vol 17, N

ut has become increasingly commonplace.1

This can be ascribed to the simplicity of theprocedure itself, as well as its minimal invasive-ness and comparatively low cost compared withconventional surgical intervention. Despite itssimplicity, however, complications will invariablyarise, partly because of the relative inexperienceof the clinicians performing it. These complica-tions include soft tissue injury, hard tissue dam-age, biomechanical errors, and failure intrinsicto the implant itself (eg, fracture inhalation,ingestion, infection).

Soft-Tissue Injury

Soft-tissue injury can occur either duringplacement of a TAD or subsequently duringthe course of its use. Both can require exten-sive reparation.

Placement Injuries

Aside from absolute anchorage, one of the pri-mary biomechanical advantages that TADs offeris the ability to exploit the dentition’s center ofresistance (Fig 1). Relocating the point of forceapplication—either tensile or compressive—

from the orthodontic appliance to a region

o 2 (June), 2011: pp 168-179

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169Complications of TAD Therapy

nearer the anatomical center of resistance en-hances the translatory movement of teeth. Thisis in contrast to the cyclical succession of crown-tipping and root-uprighting observed with tradi-tional orthodontic mechanotherapy.2,3 This of-ten necessitates, however, that the TAD beplaced relatively apically; sometimes beyond themucogingival junction. Mucosal tissue, as op-

Figure 1. (A) Preorthodontic panorex exhibitingmultiple missing teeth. The treatment plan entailedclosing all maxillary space except for the left lateralincisor. The maxillary right second molar is to beprotracted (note position relative to impacted thirdmolar). (B) Although the maxillary right second mo-lar has been protracted, it still exhibits distoangularroot inclination because of the inferior placement ofthe maxillary right TAD. (C) Apical repositioning ofmaxillary right TAD to upright the maxillary rightsecond molar root.

posed to keratinized gingival tissue, generally

demonstrates the least durability and hence isthe most susceptible to impairment (Fig 2).4-6

A variety of implant systems are available onthe market and most, if not all, include theoption of drilling a pilot hole. This step is anecessity when one uses a self-tapping ratherthan a self-drilling system. An initial method tominimize soft-tissue laceration during the place-ment of a TAD is the proper preparation of theimplant site before drilling the pilot hole, par-ticularly when placing it in the mucosal tissue.Several techniques have been proposed. Park etal7 advocate a small vertical stab incision withflap reflection, whereas other authors8 recom-

end the use of a biopsy tissue punch of appro-riate diameter. Eliminating soft tissue from theroximity of the intended pilot hole will de-rease the likelihood of its entanglement withhe surgical drill. Figure 3 demonstrates the con-equence and rectification of such entangle-ent. Any clinician who has contoured a den-

ure tooth using an acrylic bur while wearingatex gloves can envision an analogous circum-tance.

In the event of soft-tissue entanglement, asiderom initial insult often more problematic is thextrication of the surgical drill from the mucosafter osseous engagement where the clinicianust reverse the handpiece engine directionhile maintaining drill stability. Any long-axiseviation of the drill while doing so could po-entially increase the diameter of the pilot hole.

hile there is usually a diameter differential ofpproximately 20% between the pilot hole drillnd TAD (ie, a 1.2-mm pilot hole drill for a.5-mm TAD), this disparity is required to en-ure implant engagement in sound corticalone; that which is uncompromised by the in-erently traumatic procedure of drilling itself.9

One may proffer that a reasonable alternativeto the aforementioned complications is to sim-ply use a self-drilling implant system. Although itmay seem intuitive that elimination of a pilothole may reduce the incidence of mucosal per-forations, tears can still occur during advance-ment of the TAD itself. Figure 4 demonstratesthe result of mucosal encroachment into theTAD threads during insertion despite appropri-ate pilot hole establishment. This is particularlytrue with TADs exhibiting a significant degree oftaper from tip to transmucosal collar. The diam-

eter of soft tissue preparation should be at least

cssa

able online.)

170 Roncone

as large as the widest part of the TAD. Further-more, a distinct advantage of pilot hole creationwhen placing TADs interradicularly is the en-hanced ability of the clinician to differentiatecortical bone from root. It has been well dem-onstrated that cortical bone thickness varies notonly between individuals but also within thesame individual in different areas of the maxillaand mandible.10-13 As such, one must be able todistinguish the cortex from root penetration orapproximation. Self-drilling TADs require anominal amount of pressure to penetrate andadvance the implant through the cortical plate.Without a pilot hole, the clinician may be de-prived of the tactile perception required to rec-ognize that the root surface has been compro-mised.14 In addition, although a pilot hole drillould also potentially contact a root, less pres-ure needs to be exerted with a drill than with aelf-drilling TAD. Failure of the drill to advance

Figure 3. (A) Drilling of pilot hole without adequatesoft-tissue preparation. The mucosa became ensnaredin the surgical drill necessitating sutural restoration.(B) Repair of mucosal laceration with 4-0 silk. (Colorversion of figure is available online.)

Figure 2. (A) Maxillary right TAD repositioned api-cally to enable second molar root uprighting whichresulted in mucosal tear. The original implantationsite is visible mesial to the second premolar crown(arrow). (B) Mucosal tear sutured with 4-0 plain gutand healed well despite proximity to frenal attach-ment (A). (C) Biomechanics used to upright root ofmaxillary right second molar. Auxiliary wire permit-ted force delivery nearer center of resistance and aclockwise moment. (Color version of figure is avail-

fter a few millimeters—the juncture at which,

171Complications of TAD Therapy

depending upon anatomical location, the clini-cian would normally expect a marked decreasein resistance as cancellous bone is encoun-tered—could indicate root encroachment.Moreover, a self-drilling TAD is sharper andmore likely to penetrate a root than either aself-tapping TAD or a pilot hole drill—neither ofwhich can easily puncture a root.15

Postplacement Injuries

Once the TAD is in place, subsequent injury canarise from either the TAD itself or from adjunctsattached to the TAD.

Peri-Implantitis

In addition to its inherent fragility, another del-eterious characteristic of movable soft tissue is itsproclivity toward irritation or ulceration. Figure

Figure 4. (A) Mucosal tear distal to TAD (arrow).Although a tissue punch was used here, the threads ofthe TAD entangled the mucosa during insertion andresulted in a 5-mm tear. The hematoma mesial to theTAD is the result of local anesthetic infiltration. (B)Sutural repair of mucosal laceration with 4-0 plaingut. (Color version of figure is available online.)

5 demonstrates inflammation surrounding a

TAD located in vestibular mucosa 1 week afterplacement. The degree of tissue mobility in thisparticular region is evident by the numerousfrenal attachments in the area.

Although not as common, attached keratin-ized tissue is not immune from such sequelae.Figure 6 shows an orthodontic implant insertedinto the hard palate. In this particular instance abulk of composite was placed over the implanthead to minimize tongue discomfort. It also,however, complicated hygienic maintenance ofthe TAD. Regardless of the site of implantation,proper oral hygiene of the TAD and surround-ing area cannot be overemphasized. Soft-tissueinflammation and the resultant presence ofchronic inflammatory cells can affect the under-lying bone and lead to implant failure.7 A rub-ber tip stimulator or water irrigation deviceshould be used in any area that is not accessiblewith a conventional toothbrush. Even with a me-ticulous hygienic protocol, however, movablemucosa still remains susceptible to irritation andhence inflammation.

Damage from Adjuncts

Although soft-tissue damage from attachments,such as coil springs or elastomeric modules, canoccur with traditional orthodontic therapy,greater care must be taken when such adjunctsare used in conjunction with TADs. These ad-juncts may extend to areas, such as the vestibule,retromolar pad, and maxillary tuberosity whichare more susceptible to impingement. Figure 7

Figure 5. Soft-tissue inflammation surrounding aTAD placed in mucosa. Note also several frenal at-tachments which must be avoided. This makes mov-able mucosa a less desirable location for TAD place-

ment. (Color version of figure is available online.)

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172 Roncone

exhibits mucosal overgrowth of an auxiliary wirethat extended too deeply into the maxillary ves-tibule. In this case envelopment was so comp-lete that surgical excision was required to liber-ate the wire. Instances in which there exist alarge distance between a TAD and the site ofattachment of a spring or elastomeric chain, theuse of an auxiliary wire to prevent soft tissueimpingement may be useful to counteract archcurvature (Fig 8).

Hard Tissue Trauma

Root Damage

Perhaps the greatest concern when placingTADs in tooth-borne regions is the possibility ofroot encroachment, as is evidenced by the vol-ume of literature devoted to the topic.16-20 Sim-

Figure 6. (A) Inflammation of palatal gingiva sur-rounding TAD. A ball of composite was placed overTAD to minimize irritation to the tongue. A highpalatal vault complicated hygienic maintenance ofimplant. (B) Extent of induration of edematous tissueafter TAD removal. Inflammation completely resolvedin 3 weeks. (Color version of figure is available on-

line.)

larly, the orthodontic literature is replete withtrategies to avoid root contact either via radio-ogical navigation or clinical positioninguides.21-28 Precise placement and avoidance ofoots is paramount not only to the clinical suc-ess of the TAD but also in the prevention ofatrogenic complications and their subsequent

edicolegal consequences.When a root is violated, the severity of the

njury depends upon the extent of the damagend the speed with which the insult is alleviated.bviously, root penetration is much more severeconsequence than root impingement. Simi-

arly, root impingement which is immediatelyorrected (eg, a root is contacted upon insertion

Figure 7. Mucosal overgrowth of protraction auxil-iary wire. (Color version of figure is available online.)

Figure 8. Use of an auxiliary wire to prevent coilspring impingement on soft tissue. This is useful ininstances in which there is a long span between TADand site of spring attachment because of the curvatureof the alveolus. (Color version of figure is available

online.)

173Complications of TAD Therapy

but then the TAD is redirected) will repair morerapidly and to a greater extent than a TAD left inplace wherein chronic inflammatory cells havebeen recruited and clastic activity has begun.29

Fortunately for both the patient and practitio-ner, several studies have indicated that when aninsult affects only the periodontal ligament andcementum, complete healing typically ensues af-ter removal of the TAD.5,13,14,18,30,31 Injuries in-volving pulpal tissue, however, are more seriousand may result in the loss of the affected tooth.

The initial step in avoiding root transgressionis proper treatment planning. When a TAD isplanned for an interradicular region, divergenceof the adjacent roots should be accomplished byaccentuated bracket positioning. This should beperformed at the onset of treatment to ensurethat mature bone exists at the target location bythe time the TAD is ready to be placed. To avoidmoving a root into an existing TAD, site selec-tion should take into account not only the initialposition of the TAD but also the location of theTAD relative to the dentition both during and atthe conclusion of proposed tooth movement.

Tactile perception, although useful, shouldnot be the only feedback upon which an opera-tor relies when placing a temporary orthodonticimplant. As previously noted, bone density, evenin identical anatomical sites, varies widelyamong individuals. What might be perceived asroot impingement in one individual may just beparticularly dense cortical bone in another.Therefore, periapical radiographs should beused to verify TAD position during placement(Fig 9). Ideally one should take a progress peri-apical after a sufficient amount of TAD threadshave engaged the cortical plate to provide sta-bility, but before full insertion when redirectionis considerably more difficult (Fig 10). This isobviously unnecessary in edentulous regions. Ifperiapical radiographs are not able to be ob-tained, profound anesthesia should be avoidedto elicit patient reaction while inserting a TAD.14

If a root is encountered during insertion, thepatient will generally report the sensation of adull pain.

Another potential complication—althoughpossibly occurring in any type of orthodontictooth movement—is apical root resorption.Unique to orthodontic implant therapy, how-ever, is the fact that TADs enable magnitudes of

tooth movement not previously observed by

Figure 9. (A) Periapical radiograph taken at time ofTAD placement reveals impingement on anterioraspect of mesial root of first molar. (B) TAD wasimmediately removed and periapical obtained todocument extent of root damage. (C) One monthafter initial insult defect in root has been repairedthough lamina dura has not yet completely reossi-fied. TAD was repositioned anteriorly the same dayof initial placement.

gin

174 Roncone

non-surgical means. Figure 11A, B show initialand progress lateral cepholgrams in which anextreme overjet was abridged. As can be seen inFigure 11C, D, the patient experienced moder-

Figure 10. TAD position and angulation is radio-raphically assessed prior to complete insertion intonterradicular regions simplifying redirection whenecessary. (Color version of figure is available online.)

Figure 11. (A) Initial lateral cephalogram exhibitinlateral cephalogram demonstrating substantial maxillmaxillary incisors and improvement in lip competenceincisors after extensive incisor retraction. (D) Apical r

right canine following extensive retraction.

ate apical root resorption of the maxillary ante-rior teeth. Whether this particular patient waspredisposed to root resorption and experiencedit irrespective of TAD usage cannot be ascer-tained. Although not necessarily indicative of acausal relationship, anecdotal evidence suggeststhis may be the case as the only teeth exhibitingroot resorption were those that moved the great-est distance.

Figure 12 demonstrates a patient in whomTADs were used to intrude molar teeth to cor-rect an anterior open bite malocclusion. Signif-icant apical root resorption is noted after themolar intrusion. Mimura described a similar cir-cumstance and postulated that teeth moved withthe assistance of TADs may contact structures—such as the cortical bone lining the incisive fo-ramen and the lingual cortical plate—which arenot normally encountered in conventional orth-odontic therapy.32

nificant overjet and lip incompetence. (B) Progresscisor retraction. Note remnant of bone labial to theApical root resorption noted on the maxillary central

resorption noted on the distal aspect of the maxillary

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175Complications of TAD Therapy

Osseous Damage

Although not a very common occurrence, dam-age to bone can occur, particularly during pilothole creation. Osseous drilling necessitates anominal degree of trauma to the immediatesurrounding bone. Several precautions can beundertaken to minimize this insult, all of whichaim to minimize heat generation and reduce therisk of osseous necrosis. Foremost is proper drillspeed. A high-torque, slow drill speed in therange of 300-500 rpm is ideal.14 To achieve this,

speed reduction (64:1 or 16:1 gear ratio) con-ra-angle attachment should be used. Variablepeed handpieces can also be used at low rpm,owever maintaining the proper rpm with aheostat can be more difficult. Irrigating hand-ieces are available, but are not generally part ofn orthodontist’s armamentarium, nor needhey be. Sterile saline expressed from a sterile

onoject (Vitality Medical, Salt Lake City, UT)

Figure 12. (A) Pretreatment lateral cephalogram exopenbite. (B) Progress lateral cephalogram showing oRoot resorption noted on palatal root of maxillary firresorption exhibited on distal aspect of maxillary secinferior aspect of the maxillary sinus.

yringe onto the bur while drilling will suffice. If

closed water system is used, sterile water orormal saline can be delivered from the air/ater syringe. It is important that only sharprills be used as dull drills generate excessiveeat.

Finally, insertion of the TAD, whether hand-r engine-driven, should be done slowly. Bone isiscoelastic and will expand in response to pres-ure from the advancing TAD. This is particu-arly true with tapered TADs as diameter in-reases with insertion.

Biomechanical Errors

As with traditional orthodontic mechanics,proper vector control using implants is vital toensure predictable movement of teeth. Poor vec-tor management can, in fact, be magnified usingTADs because of their enhanced capacity for

ts a high angle Class II malocclusion with anteriorite resolution after 18 months of molar intrusion. (C)olar after significant orthodontic intrusion. (D) Rootpremolar likely caused by cortical plate forming the

hibipenbst mond

absolute tooth movement. Figure 13 demon-

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176 Roncone

strates the result of inadequate directional con-trol.

The same is true when using multiple TADs.Bilateral placement of TADs at, or just inferior(in the case of the maxilla) to, the mucogingivaljunction may not ensure nor necessarily pro-

Figure 13. (A) Pretreatment occlusion exhibitingnormal occlusal plane. (B) Improper vector manage-ment producing a canted mandibular occlusal plane.(C) Elastomeric chain used to protract mandibularsecond molar. The tensile force has both horizontaland vertical components. (Color version of figure isavailable online.)

duce an identical result with regard to the trans-

verse anatomical plane. The use of multilobu-lated crimpable hooks is useful in this regard asthe retraction vector can be altered as needed tocounteract any cant effects which may develop(Fig 14).

Intrinsic Failure

Complications involving TAD ingestion or inha-lation are relatively rare. Such occurrences, how-ever, should be incorporated into any compre-hensive informed consent. Ingestion of a TAD isgenerally a benign event.33 Inhalation, by con-rast, could have far more deleterious conse-uences requiring extensive medical interven-ion. Precautions such as safety ties,34 whenractical, or placement of gauze in the posteriorropharynx should be considered. Although it isasy to secure small hand drivers with dentaloss or the equivalent to permit retrieval, TADsue to their minute dimensions generally do not

end themselves to such precautions. Implantrivers (hand drivers, engine drivers, etc.)hould actively engage the TAD so that it isecurely held and cannot be displaced by gravitylone. As implant systems have evolved, mostave incorporated this feature.

Far more prevalent is the failure of the TADtself.4 Potential causes include (1) placement

of the TAD into inferior quality bone, (2) lackof primary stability, (3) excessive loading ofthe TAD after placement, (4) trauma to theTAD from masticatory or other forces, and (5)

Figure 14. Although bilateral TADs were placed inidentical positions relative to the mucogingival junc-tion, a maxillary occlusal cant developed during inci-sor retraction. Asymmetric application of coil springswas used to correct the cant. (Color version of figure

is available online.)

177Complications of TAD Therapy

osseous injury during placement. As might beexpected, the literature devoted to this topic isquite voluminous. It should be noted that aninherent limitation of orthodontic implants,which is often overlooked, is their design notto osseointegrate (they are by definition tem-porary). It must, therefore, be expected that acertain percentage of ideally placed orthodon-tic implants will fail; particularly when failurerates of traditional, osseointegrated, pros-thetic implants can range from 2% to 8%.35-37

Loosening of a TAD is fairly innocuous andoften a slightly mobile TAD—if otherwiseasymptomatic—can continue to be used. Aworst-case scenario is that the TAD fails andmust be replaced with a larger diameter implantor relocated to a suitable alternate site. Moreproblematic is TAD fracture, which is most likelywhen a TAD endures excessive torque eitherupon insertion or removal. Because of the ex-tent and variety of orthodontic implants avail-able, a spectrum of maximum torque values ex-ists. Factors such as design, diameter, amountand acuteness of taper, and titanium composi-tion affect the torsional properties of TADs. It istherefore incumbent upon manufacturers tospecify the maximum torque values for each ofthe orthodontic implants they produce. Unlessthese TADs are both placed and removed with atorque-calibrating device, however—which isusually not the case—the values are relativelymeaningless. As a general rule, fracture tends tobe greater in small diameter TADs (�1.5 mm),TADs made of pure (nonalloyed) titanium, andthose that are inserted via the drill-free method,as greater torsional strain is encountered.8,14

In the event of fracture, remediation is de-pendent upon the location of the fracture andits position relative to the periosteum. If asufficient length of the implant body remainsabove the soft tissue, the implant may begrasped with a hemostat or Mathieu plier andremoved. If, however, the fracture is eithersubgingival or submucosal, a small flap mayneed to be elevated to expose the body rem-nant. If flush with the periosteum a smallround bur in a slow speed handpiece maybe used to trench around the implant to ex-pose enough of the body to enable properpurchase by an instrument. Lastly, a trephinemay be used to excise both the fractured TAD

and a small diameter of bone surrounding it.

Such an intervention, however, is generallybeyond the scope of both the orthodontist’straining and armamentarium and referralshould be made to the appropriate specialist.

Finally, each clinician should adhere to anestablished surgical protocol to reduce the inci-dence of postoperative infection. Steps includethe use of an aseptic surgical technique, pre- andpostoperative antimicrobial rinse, and an appro-priate postoperative antibiotic regimen.

Discussion

This article outlines the more common prob-lems encountered during placement of tempo-rary orthodontic implants. This is, however, notan exhaustive list of possible complications.Kravitz and Kusnoto38 in a review enumerateadditional anomalies, such as air subcutaneousemphysema and partial osseointegration (a com-plication of which is TAD fracture upon re-moval).

Most of the complications mentioned can beappropriately described as “errors of inexperi-ence;” these are not problems that would gener-ally be encountered by a clinician proficient inthe surgical procedure. Proper treatment plan-ning, recognition of potential complications,and familiarity with the implant system can sig-nificantly limit these sequelae. As with any newtechnique, however, clinical aptitude is attainedwith experience. Unlike surgeons, or even re-cent orthodontic graduates, who have had thebenefit of residency programs to refine theirsurgical skills, the orthodontic practitioner mustacquire proficiency without the supervision nor-mally afforded those learning a new technique.

Conclusions

Ever since Creekmore and Eklund’s landmarkarticle39 in 1983, the possibility of absoluteskeletal anchorage has been an aspiration oforthodontic clinicians. The introduction anduse of TADs in the last decade has revolution-ized orthodontic mechanotherapy and en-abled “orthognathic-like” results. For the or-thodontist who is considering or just beginn-ing to place implants, the following recom-

mendations are suggested:

178 Roncone

1. Insert the first several TADs in “safe” re-gions—areas in which the possibility of en-croachment upon adjacent anatomical struc-tures is negligible (eg, an edentulous ridge orwell-ossified extraction site). This will permitthe clinician to acquire a feel for the implan-tation procedure with minimal risk.

2. Propensity for inflammation and susceptibil-ity to injury make the oral mucosa ratherinhospitable to TADs and should be avoidedwhen possible. Instances in which placementin such tissue cannot be avoided, emphasismust be placed on exquisite oral hygiene ofthe TAD and surrounding area. Similarly, fre-nal attachments should be avoided when pos-sible; however, hard tissue limitations occa-sionally prevent this. In these instances, anincisional frenectomy can be performed.40

3. Because soft-tissue complications of some sortare inevitable if enough TADs are placed, it isadvisable to have a basic suture kit availableso that minor complications can be managedby the orthodontist.

4. In cases of root trauma, insults should becorrected as soon as possible and compro-mised teeth should be monitored with peria-pical radiographs. Fortunately, the recupera-tive potential of a dental root is immense as isevidenced by its tolerance of an apicoectomy.

5. A review of dental anatomy is beneficial, par-ticularly as it pertains to the greater palatineartery and nerve.

6. Orthodontic implant complications are ubiq-uitous and not unique to any particular im-plant system. There are inherent differencesamong the various systems available and it isbeneficial to understand the advantages anddisadvantages of each.

AcknowledgmentsThe author thanks Dr Glenn Sameshima and the Universityof Southern California School of Dentistry, Department ofOrthodontics for their assistance in the research for themanuscript.

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