Orthodontic extrusion for implant sitedevelopment revisited: Adetermined by anatomyMark N. Hochman, DDS,1 Stephen J. ChDennis P. Tarnow, DDS3

A contemporary approach to achievingoutcomes requires the knowledge toexecute complex interdisciplinary care.orthodontic extrusion requires an unders

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Orthodontic extrusion, also known as forced

1FormerPrivate PraYork, USA;http://dx.doi.org/10.1053/j.sodo.2014.06.007eruption, was rst identied as a treatmentoption to change the relative position of teethwithin the alveolar housing through active ver-tical eruption of teeth in an occlusal direction.6

The application of a controlled orthodonticforce to teeth resulted in a mechanicallymediated eruption to occur, hence the term

& 2014 Elsevier Inc. All rights reserved.1073-8746/12/1801-$30.00/0

Director of Implant Education, Columbia University College of DentalMedicine, New York, New York, USA.

Address correspondence to Mark Hochman, DDS, 150 East58th Street, Suite 3200, New York, NY 10155, USA. E-mail:PerioOrtho@aol.com

208 Seminars in Orthodontics, Vol 20, No 3 (September), 2014: pp 208227ontology and Implant Dentistry, Department of Prosthodontics, NYUCollege of Dentistry, New York, New York, USA; 3Clinical Professor,surface, and during orthodontic extrusion an increase in the width of attachedgingiva will occur. Type 2 classication, the attached gingiva and MGJ isconnected to the root surface, and during orthodontic extrusion the gingivaltissuemoves coronally with the tooth, but an increase in thewidth of attachedgingiva does not occur. Type 3 classication; a periodontal pocket is presentand during orthodontic extrusion the free gingival margin does not movecoronally until there is a complete elimination of the periodontal pocket. Inaddition, the article provides a greater understanding of the orthodonticbiomechanical principles and techniques that should be selected based onanatomical considerations for each patient. Mastering the diagnostic andtechnical aspects of orthodontic extrusion is an invaluable addition to theinterdisciplinary practice as it can provide an effective means to treat softtissue and osseous vertical deciencies of the periodontium. Orthodonticextrusion may therefore represent a unique treatment alternative to someof the most challenging esthetic situations. (Semin Orthod 2014; 20:208227.)& 2014 Elsevier Inc. All rights reserved.

ction

e is, arguably, nothing more rewardingtoday's dentists than to gain condencebility to achieve predictable outcomes in

the esthetic zone. One testament is the mtreatment alternatives that have been deto address a wide scope of dental concerndevelopmental or pathologic processepatients causing them to seek esthetic-ressolutions in the anterior region of the oraorthodontic extrusion has emerged as avative and unique alternative for acoptimal results.15

Associate Clinical Professor, NYU College of Dentistry;ctice of Periodontics and Orthodontics, New York, New2Clinical Associate Professor, Department of Period-and principles of both disciplines of orreviews basic concepts of orthodondiagnostic periodontal classicationthat anticipates osseous and soft tissType 1 classication, the attached ginnew classicationand clinical outcomesu, DMD, MSD, CDT,2 and

optimal implant esthetic-restorativeproperly diagnose, coordinate, andImplant site development utilizingtanding of many important conceptsdontics and periodontics. This articleextrusion and emphasizes a neweme of the pre-treatment anatomyresponses to orthodontic extrusion.a is connected to both bone and root

forced eruption.7 This type of tooth movement extrusion to resolve the restorative challenge of

Figure 1. Pre-treatment view on left and orthodontic extrusion post-treatment view on right displayingreformation of the interdental papilla. Improved gingival contour and esthetics.

Orthodontic extrusion for implant site development revisited 209was initially used to change the bony topographyaround teeth by taking advantage of boneresponses to orthodontic forces. In 1972,Brown8 described such a technique as acorrective procedure toward elimination ofinfrabony defects resulting from periodontaldisease. He suggested that altering the osseousconguration through controlled toothmovement could improve and even eliminateintra-osseous vertical defects. The novel idea ofusing a discipline outside of periodontics to treatbone loss, i.e., orthodontics, can be consideredthe catalyst that led to interdisciplinary dentaltreatment used widely today to address manychallenging dental problems.

In 1974, Ingber9,10 described orthodonticextrusion as an effective means of treating teethdeemed non-restorable because of clinical crownfracture and/or subgingival dental caries. Hefurther described the use of orthodonticFigure 2. Pre-treatment view on left and orthodontic eincrease in the zone of attached gingival tissue.insufcient clinical crown length for properrestorative ferrule, which otherwise requiredeither periodontal surgical crown lengthening orexodontia as the denitive form of treatment.Ingber pointed out the resultant unfavorablecrown-to-root ratio from surgical removal ofsupporting bone when utilizing periodontalcrown-lengthening procedures. In contrast, hehighlighted the benecial effect orthodonticextrusion has on the crown-to-root ratio and theoverlying soft tissues (i.e., increase of the width ofattached gingiva). Therefore, Ingber is creditedwith advancing the concept of interdisciplinarytreatment through clinical case reports and thedetailed descriptions of using this type oforthodontics in the treatment of various restor-ative challenges.

More recently, Salama and coworkers were therst to publish a series of articles using ortho-dontic extrusion to augment bone and soft tissuextrusion post-treatment view on right displaying the

of the periodontal attachment leads to improved

Figure 3. Type 1 classication. In this anatomical situation, the attached gingiva is rmly connected to both boned o

Hochman et al210of the recipient dental implant site.1113 A clas-sication scheme related to ndings and treat-ment was developed by these authors presentingdiagnostic guidelines and the therapeutic bene-ts of using orthodontic extrusion to enhancesites receiving implants. These authors stated thenotion that a hopeless tooth is not a uselesstooth, in which they advocated using perio-dontally compromised teeth to dramaticallyimprove the esthetic-restorative implant out-come. Salama and coworkers added to the workof Ingber and Brown by using orthodonticextrusion in another clinical situation, as a pre-

and root surface, and the mucogingival junction is locatein the width of attached gingiva will occur.surgical periodontal augmentation techniqueprior to implant placement.

Figure 4. Type 1 classication. In this anatomical situationand root surface, and the mucogingival junction is located oin the width of attached gingiva will occur.conditions both esthetically and biologically.Differences in biomechanical principles thatseparate orthodontic extrusion from otherorthodontic movements are also discussed.

Principles of orthodontic extrusion

When compared to periodontal regenerationtechniques, orthodontic extrusion has theThis article focuses on a contemporaryunderstanding of orthodontic extrusion with anemphasis on discussing how the adaptive capacity

n the bone. During orthodontic extrusion, an increasepotential to be an effective alternative for hardand/or soft tissue augmentation.1417 The dental

, the attached gingiva is rmly connected to both bonen the bone. During orthodontic extrusion, an increase

atio. Dof

Orthodontic extrusion for implant site development revisited 211anatomy of the intact periodontium consists ofthe tooth cementum, bone, gingiva, and theperiodontal ligament bers. Orthodontic toothmovement affects these anatomical structures bytranslating forces to produce a predictable bio-logic response. The mechanical eruption of thetooth involves applying a direct force to the toothin a specic direction. This force creates a ten-sion on the periodontal ligament bers, makingthem stretch and elongate. This stretching of theperiodontal bers on the surface of the bone canmediate cellular changes that lead to the desiredformation of new bone.18 When orthodontic

Figure 5. Type 2 classication. In this anatomical situconnected to the root surface and not found on bonecoronally with the tooth, but an increase in the widtheruption is implemented, new bone formation isproduced at the crestal aspect of the alveolarbone and along the surface of the bone

Figure 6. Type 2 classication. In this anatomical situatioconnected to the root surface and not found on bone. Dcoronally with the tooth, but an increase in the width ofapproximate to the root.1921 Therefore, theperiodontium can be predictably manipulated byusing controlled tooth movement to provide thedesired and only non-surgical technique ofproducing new bone.

Orthodontic extrusion also has an additionalbenet that affects the overlying gingival soft tis-sues.10,11,14 There can be an increase in the spatialvolume, particularly the height, of the gingival softtissue as a result of this type of movement.4 This hasimportant clinical implications as orthodonticextrusion compared to surgical techniques isreported as the most predictable means of correc-

n, the attached gingiva and associated MGJ is rmlyuring orthodontic extrusion, the gingival tissue movesattached gingiva does not occur.ting the loss of the interdental papilla4,5,16,17,22,23

(Fig. 1). Orthodontic extrusion, therefore, providesa predictable solution in situations where there has

n, the attached gingiva and associated MGJ is rmlyuring orthodontic extrusion, the gingival tissue movesattached gingiva does not occur.

Periodontal gingival response to

supracrestal bers. As the tooth is moved to itsnew location, these bers become thesupporting structure for the reformation of

on the left is Type 1 and the image on the right is Type 2.d the position of the crest of the bone is marked in green., these landmarks need to be identied.

Hochman et al212orthodontic extrusion

The response of the periodontium to ortho-dontic forces is evident both on a macro- andbeen a loss of the height of the gingival soft tissues,which can be particularly problematic in theesthetic zone24,25 (Fig. 2).

Figure 7. Type 1 and Type 2 classications. The imageThe relative position of the MGJ is identied in blue anTo anticipate the outcome from orthodontic extrusionmicro-level. This discussion is in context with theunderstanding that the periodontal attachmentand the supracrestal bers of the gingival com-plex both play a role in the soft tissue anatomy.As these structures collectively form the attach-ment coronal to the crest of the bone, they play acritical role in changing the hard and soft tissuetopography during tooth movement.18,19 Theperiodontal ligament and the supracrestal gin-gival bers connect the tooth to the bone. As theorthodontic force moves the tooth coronally,these bers stretch; this in turn produces tensionin the bone on a cellular level, which causesbone deposition.26 The supracrestal bers playa central role in the soft tissue morphologybefore and after tooth movement. The papillaand surrounding gingival tissue is mainlycomposed of connective tissue with highlyorganized ber groups. These are the cir-cumferential, transseptal, dento-gingival, anddentoperiosteal, collectively known as theFigure 8. Type 3 classication. In this anatomicalsituation, a periodontal pocket is present and isconrmed with a loss of attachment. During ortho-dontic extrusion, the free gingival margin may notmove coronally until there is a complete elimination ofthe periodontal pocket and the eversion of the apicalattachment of the periodontal pocket producedduring extrusive tooth movement.

response is based upon an understanding of thefollowing three parameters: (1) measuring thesulcus or pocket depth prior to tooth movement,(2) determining the position of the mucogingivaljunction (MGJ) relative to the crest of the bone,and (3) transgingival probing under local anes-thesia or bone sounding to determine

on, a periodontal pocket is present and is conrmed with aee gingival margin may not move coronally until there is ahe eversion of the apical attachment of the periodontal

Orthodontic extrusion for implant site development revisited 213the interdental papilla and mid-facial gingiva inits new location. The concept of orthodonticextrusion leading to papilla regeneration istherefore a misnomer; it is more accuratelydescribed as the reformation of the papilla in anew location.

Gingival health and the absence of gingivalinammation and/or disease are critical toensuring successful biologic and esthetic out-comes.11 Tooth movement in the presence ofgingival inammation has long been understoodas a contraindication to treatment for multiplereasons. The undesirable outcomes ofaccelerated bone loss, increased mobility, andunpredictable soft tissue responses have beenreported when teeth are moved in the presenceof inammation.2628 Gingival inammationproduces a cascade of cellular responses thatdisrupts the highly organized arrangement of

Figure 9. Type 3 classication. In this anatomical situatiloss of attachment. During orthodontic extrusion, the frcomplete elimination of the periodontal pocket and tpocket produced during extrusive tooth movement.the periodontium. These pathologic changesimpact the supracrestal bers as well and canresult in changes to the osseous and soft tissueresponse producing unpredictable outcomesthat can be undesirable during orthodontictooth movement.29,30 Therefore, every effortmust be made to create a healthy tissue envi-ronment prior to initiating orthodontic move-ment of teeth.31,32

Classication of soft tissue response toorthodontic extrusion

The authors have identied three distinct out-comes of the soft tissue in response to ortho-dontic extrusion. Anticipating the gingivalthe location of the crest of the bone and whetherthere is attached gingiva connected to theroot surface and/or the periosteum of thebone.4,16,33,34Figure 10. Bodily tooth movement in which under-mining bone resorption occurs all along the entire surfaceon the pressure side of the tooth. This is contrasted bybone apposition along the entire tension surface of thetooth when moved in a horizontal direction.

Type 1: Increase of width of attached gingiva andoverall soft tissue width.

This outcome results whenMGJ is attached to theunderlying surface of the bone and the attachedgingiva is connected to both bone and rootsurface (Fig. 3). As the tooth is orthodonticallymoved in a coronal direction, one can expect anincrease in the width of attached gingiva. In thisanatomical situation, the attached gingiva isrmly connected to the bone thus preventingMGJ from migrating coronally with the tooth.Therefore, the only available biologic response ofthe attached gingiva is to expand verticallyresulting in an increased width of this zone(Fig. 4).

Type 2: Increase of overall soft tissue width withno effect on the width of attached gingiva.

This outcome results when MGJ and the attached

Figure 11. An extrusive force applied in a coronaldirection upon the facial surface of a maxillaryanterior tooth. It will produce a clockwise momentthat will cause the apex of the tooth to move in a facialdirection.

Hochman et al214Proper evaluation of these parametersprior to tooth movement increases the predict-ability of the resulting soft tissue architec-ture after orthodontic extrusion and helpsinforming the patient regarding outcomes and/or the need for additional procedures after toothmovement.

This classication describes three types of softtissue responses to orthodontic extrusion, whichare as follows:Figure 12. The series illustrates an anterior maxillary toothis applied to the facial surface of the tooth during orthodonin a facial direction if a counter-torqueing moment is noteither a fenestration or dehiscence of facial plate of bonewith a normal incisal inclination. When a coronal forcetic extrusion, it will cause the apex of the tooth to moveprovided. This will lead to an undesirable outcome ofas a consequence of this type of tooth movement.gingiva is connected to the root surface and notthe surface of the bone (Fig. 5). Clinicalscenarios where MGJ is located on the rootsurface include developmental factors such as abony dehiscence defect or a Type 2 alteredpassive eruption or pathological situations suchas a history of bone loss. As a result, when thetooth moves coronally, it carries along with it thepoint of attachment of MGJ and the attachedgingiva (Fig. 6).

Figure 13. A clinical example of orthodontic extrusion using a provisional restoration to apply a force through thelong axis of a tooth. This technique minimizes a forward clockwise movement from being produced during verticalextrusion of these teeth thus preserving the facial plate of bone during this type of tooth movement. Pre-treatmentview of teeth number 8 & 9 requiring orthodontic extrusion of non-restorable fractured teeth.

Figure 14. A clinical example of orthodontic extrusion using a provisional restoration to apply a force through thelong axis of a tooth. This technique minimizes a forward clockwise movement from being produced during verticalextrusion of these teeth thus preserving the facial plate of bone during this type of tooth movement. Use of intra-coronal elastic thread applied through a provisional restoration. View of provisional restoration showing the accessholes in which elastic threads will pace to engage teeth number 8 & 9.

Figure 15. A clinical example of orthodontic extrusion using a provisional restoration to apply a force through thelong axis of a tooth. This technique minimizes a forward clockwise movement from being produced during verticalextrusion of these teeth thus preserving the facial plate of bone during this type of tooth movement. Use of intra-coronal elastic thread applied through a provisional restoration.

Orthodontic extrusion for implant site development revisited 215

movement is completed.

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Hochman et al216Type 3: Width of attached gingiva and overallwidth of soft tissue are unchanged.

After orthodontic extrusion is completed, theposition of the free gingival margin has notmoved. This outcome is found in cases wherethere has been an advanced loss of periodontalattachment on the surface of the root and there isIt is important to diagnose which anatomicalsituation is present, Type 1 or Type 2, prior totooth movement so that one may anticipate theresulting tissue architecture (Fig. 7). Additionalsoft tissue procedures, such as soft tissue grafting,may be needed in Type 2 situations to increasethe zone of keratinized tissue after tooth

Figure 16. A clinical example of orthodontic extrusionlong axis of a tooth. This technique minimizes a forwardextrusion of these teeth thus preserving the facial plate oview on the left and the post-treatment orthodontic extrugingiva as this patient exhibits a Type 1 classication.a periodontal pocket present (Fig. 8). In thissituation, neither the MGJ nor the attachedgingiva is connected to the root surface.Therefore, before there is any gain in gingivalwidth, the periodontal pocket must rst be fullyeliminated through tooth movement. Thisextrusive movement results in a completeeversion of the base of the periodontal pocketprior to observing any changes in the gingivalwidth. If the depth of the pocket is greater thanthe distance the tooth is extruded, there will beno increase of soft tissue width (Fig. 9).

With the aforementioned understanding ofhow the pre-existing anatomy inuences the softtissue response to orthodontic extrusion, itshould be mentioned that surgical and/orinammatory insults would change the outcomesdescribed above. A series of studies were con-ducted in which supracrestal berotomies wereperformed simultaneously with forced eruptionto determine if the osseous and soft tissueresponses could be altered.20,35 The primaryobjective of these studies was to eliminate theneed for a subsequent surgical crown length-ening in patients with insufcient clinical crownlength of fractured teeth. The studies demon-strated that intra-sulcular incisions made to thebone crest, i.e., berotomies, performed simul-taneously with orthodontic extrusion eliminatedthe need for a subsequent surgical crown-lengthening procedure on these teeth. Thesendings conrmed that the surgical dissection ofthe supracrestal bers prevented coronal move-ment of bone during orthodontic extrusion.

g a provisional restoration to apply a force through theckwise movement from being produced during verticalone during this type of tooth movement. Pre-treatmentn on the right. Note an increase in the zone of attachedAdditionally, it was demonstrated that there was areduction in the increase of the gingival widthwhen compared to teeth in which berotomieswere not performed. These studies concludedthat berotomies alter the coronal migration ofboth the osseous and gingival soft tissues throughthe disruption of the supracrestal bers.20,35 It istherefore critical to identify the soft tissue clas-sication type and the intended use of ortho-dontic extrusion when considering berotomies.If crown lengthening is the goal of the ortho-dontic extrusion, berotomies may be indicatedas an adjunctive procedure as long as an increaseof soft tissue width is not required. However, ifimplant site development with tooth removal isthe treatment endpoint, one should rst deter-mine the soft tissue classication and consider

Orthodontic tooth movement is traditionally

Figure 17. A clinical example of orthodontic extrusion using a provisional restoration to apply a force through thelong axis of a tooth. This technique minimizes a forward clockwise movement from being produced during verticalextrusion of these teeth thus preserving the facial plate of bone during this type of tooth movement. Flaplessextraction of teeth numbers 8 and 9 with immediate implant placement.

Orthodontic extrusion for implant site development revisited 217understood as a discipline that is concerned withspace management in the three planes of space:sagittal, coronal, and transverse. The primarymovements of teeth are related to tooth move-ments that facilitate the correction of bodilymovement, rotations, tipping, torque, and spacewhether berotomies will interfere with thedesired soft tissue outcome. Note, in almost allsituations of implant, site development combinedwith tooth removal berotomies is contra-indicated, as they will impede the maximumamount of bone that can be formed.

Principles of orthodontic extrusion

BiomechanicsFigure 18. A clinical example of orthodontic extrusion usinlong axis of a tooth. This technique minimizes a forward cloextrusion of these teeth thus preserving the facial plate oextraction of teeth numbers 8 and 9 with immediate impmanagement in the faciallingual, inciso-gin-gival, and mesialdistal directions.

A review of literature on the subject oforthodontic extrusion reveals that it has beenreferred to as a simple or uncomplicatedmovement.8,9,11 The authors have come tounderstand that, although applying such a forcemay be simple, the effects of such a force arefound to be far more complicated than onemight expect. A more thorough analysis of theapplication of force, center-of-resistance, andresultant movement demonstrated that ortho-dontic extrusion is complex requiring anunderstanding of multiple variables in order toachieve predictable results.

A simple movement, in orthodontic terms,refers to a movement that results from theapplication of a vector of force in a singleg a provisional restoration to apply a force through theckwise movement from being produced during verticalf bone during this type of tooth movement. Flaplesslant placement.

direction, producing a movement in a singledirection. An example is horizontal bodilymovement of a tooth (Fig. 10). More complexmovements are produced when a force is appliedat a specied distance from the center-of-resistance resulting in a rotational movementknown as a moment (Fig. 11). This specicmovement has evenmore complexity particularlywhen it occurs in a constrained body, such as atooth held in the alveolar bone.

One must also keep in mind that the currentgeneration of orthodontic bracket designs used

in xed appliances were never intended for purevertical extrusive movements. These bracketswere designed to optimize movement of teethinto an idealized position within the alveolarbone. In contrast, orthodontic extrusion oftenhas the intended objective to move teeth toextreme positions, often to the point of extrac-tion. In essence, effective tooth movement forimplant site development involves moving teethto the limits of the alveolar bone. This outcome ishampered by current bracket design technology,as will be addressed later.

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Hochman et al218Figure 19. A clinical example of orthodontic extrusionlong axis of a tooth. This technique minimizes a forwardextrusion of these teeth thus preserving the facial pImmediate post-operative view on the day of removalsurgical view with nal restorations of the maxillary angingival tissues, retention of the interdental papilla, andteeth numbers 8 and 9 resulting in a favorable esthetic-anterior maxillary tooth during orthodontic extrusionapplied directly through the center-of-resistance into thethe tooth will move in that same direction. This will elimapex of the tooth during extrusion.g a provisional restoration to apply a force through theckwise movement from being produced during verticalof bone during this type of tooth movement. (A)

eeth numbers 8 and 9 on the left, and 9-month post-ior teeth on the right. Note the general health of theimproved clinical crown length (tooth proportion) oftorative implant outcome. (B) This series illustrates ano a provisional restoration. When a vector of force isovisional restoration in a coronal direction, the apex ofte the undesirable forward clockwise movement of the

Figure 20. Clinical exam shows a patient with 34 mm of gingival recession and 5 mm of probing depths on teethnumbers 8 and 9. The patient's chief complaint included loss of interdental papilla, food entrapment in space andexcessive mobility of these teeth.

Orthodontic extrusion for implant site development revisited 219Anatomic considerations in the estheticzone

The biomechanical principles of orthodonticextrusion are also affected by the anatomy of thepre-maxilla. Therefore, implant site develop-ment and papilla reformation in the anteriormaxillary region present challenges not found inthe posterior region since these teeth have anupright and vertical axial inclination. Maxillaryanterior teeth have an inherent proclined axialinclination. This angulation can be measuredusing standard cephalometric analysis such as theSteiner analysis. The analysis uses the interincisalangle andmaxillary central incisor to NA angle todetermine if the inclination of the maxillaryincisor is normal, retroclined, or proclined rel-ative to the skeletal base.36,37 The anterior toothwith a proclined axial inclination will produce aforward clockwise (leftright) moment upon theFigure 21. Radiographic evaluation reveals 4050% horizoradiographs. In addition, CBCT suggests a lack of labial capex of a tooth when moved in a coronaldirection. The forward clockwise moment willcause the apex of the tooth to be driven in a facialdirection with possible perforation through theapical portion of the facial alveolar bone plate. Itis interesting to note that the dental literature hasrecently documented that the facial plate of bonethickness on anterior teeth is 0.51.0 mm onaverage (0.3 mm) even when 10 mm apicalfrom the CEJ.3840 Therefore the more proclinedan anterior tooth is, the greater the risk of per-foration and the greater the need to counteractthe forward clockwise moment at the apex(Fig. 12). These authors contend that the axialinclination of anterior teeth requires a morecareful evaluation of this facialpalatal perspec-tive prior to orthodontic extrusion movement. Inaddition, careful consideration with respect toappliance design is warranted to prevent apicalbone perforation or facial dehiscence.ntal bone loss on teeth numbers 8 and 9 in periapicalortical plate of bone on teeth numbers 8 and 9.

Previous publications have documented a highincidence of fenestrations as a result of ortho-

Orthodontic edgewise brackets are designedwith an angulation of tip and torque incorpo-

Figure 22. Orthodontic extrusion of teeth numbers 8 and 9 with a base archwire and a secondary archwire (0.016NiTi) to produce vertical extrusion. Active tooth movement is performed over a 12-month period. Extensiveocclusal equilibration was required during orthodontic extrusion. Note the new position of the gingival marginand improved position of the interdental papilla.

Hochman et al220dontic extrusion. This undesirable outcome wasmost likely the result of a lack of control of theforward clockwise moment that was producedduring orthodontic extrusion.9,10,16,41

Torque control can be managed in threedifferent ways: (1) negative torque brackets incombination with rectangular archwires, (2)vertical loops with rectangular archwires, and (3)bracket-less technique by using a tooth-bornexed provisional restoration to anchor theextrusive force. Each of these techniques will besubsequently discussed.Figure 23. Orthodontic extrusion of teeth numbers 8 andNiTi) to produce vertical extrusion. Active tooth movemenmonths of stabilization was provided after active tooth movand the placement of dental implants. Left image shows the& 9 during treatment which was necessary. Right image is oNote the reformation of the interdental papilla on teeth 8completion of tooth movement.rated into every bracket specic for each indi-vidual tooth of the maxillary and mandibularjaws. Andrews popularized this treatmentapproach.42 This is accomplished by the bracket'sslot design and angulation to the bracket base.Negative high-torque brackets used in the pre-maxillary region will provide increased lingualroot torque to position the apex of the tooth roottoward the palate. It is noteworthy that a rec-tangular archwire needs to be engaged in thebracket slot when an edgewise bracket is used tocontrol torque as this can maximize the force9 with a base archwire and a secondary archwire (0.016t is performed over a 12-month period. An additional 6ement to allow bone maturation prior to tooth removalrepositioning of brackets on the root surface of teeth 8f the nal position of teeth after orthodontic extrusion.& 9 and an increase in the width of attached gingiva at

exerted to the apex of the tooth. Utilizing roundarchwires in an edgewise bracket cannot effec-tively produce proper counterbalancing move-ments. Therefore, it is equally important to usethe proper size and shape of rectangular arch-wires when relying upon orthodontic couplingforces to control the clockwise moment duringorthodontic extrusion. The authors have usedthis approach with success.

individually constructed archwires that possesswire-specic congurations. For instance, the useof vertical T loops can be made using a rec-tangular Beta-Titanium wire to produce a verticalextrusive force. This type of wire constructionallows greater control in the vertical directionwhile simultaneously enabling effective roottorque control that is produced by a rectangulararchwire. The negative implications of using

Figure 24. Orthodontic extrusion of teeth numbers 8 and 9. Pre-treatment radiograph (far left) displays 40% to 50%horizontal bone loss prior to movement. Sequential radiographs taken at six, nine and twelve months demonstratesthe reformation and improved vertical height of the alveolar crest of bone that was achieved during treatment.

Orthodontic extrusion for implant site development revisited 221A second effective means of controlling roottorque during orthodontic extrusion is usingFigure 25. Cross-sectional CBCT radiograhic views of teecompletion of tooth movement. Controlled facial extrusincreased bone dimensions in both the vertical as well as thnon-surgical bone augmentation using orthodontic toothdental implants at site numbers 8 and 9.vertical T loops and the like can be the addi-tional time it takes to construct these appliances.th numbers 8 (left image) and 9 (right image) at theion in combination with vertical extrusion producede buccallingual dimensions of the alveolar ridge. Thismovement was sufcient to allow the placement of

The comfort of the patient is also a factor whenusing archwires with loops and elaborate designs;

along the long axis of the tooth. A tooth-borneprovisional restoration offers this unique

Figure 26. A apless extraction of teeth numbers 8 and 9 was performed concurrently with immediate implantplacement at site numbers 8 and 9. Note soft tissue preservation of the interdental papilla and the surroundingnormal gingival architecture.

Hochman et al222however, when properly designed, they can bewell tolerated.

A third means for providing effective roottorque control during extrusion is by applying aforce from an alternative point on the tooth.A biomechanical appliance design in which theforce vector moves through the center-of-resistance of the tooth minimizes and canoften eliminate the undesirable forward clock-wise moment that is seen when a facial bracket isplaced on the tooth. The key factor in the designof such an appliance is to align the vector of forceFigure 27. Occlusal clinical view of implant position at sitRadiograpic view of implants immediate post implant plarequirement. Full-coverage acrylic provisionalrestorations used to house the erupting toothnot only provide long-axis vectoring forces butalso a more esthetic option during movementwhen compared to bracket placement on thelabial surface of an anterior tooth since there areno buccal brackets on these teeth (Figs. 1319).

There are many creative options using aprovisional restoration as an orthodontic appli-ance. The following features need to be presentto accomplish these goals. The provisionalrestoration needs to be supported by thee number 8 and 9 immediate post implant placement.cement.

adjacent teeth and/or implants. The tooth to beextruded requires sufcient reduction of the

The biomechanical advantage to employing aprovisional restoration is shown in the accom-

Figure 28. The images from left to right show a series of steps required in the fabrication of a properly contouredimmediate implant provisional crowns at the time of implant placement. The development of a proper emergenceprole in the subgingival area tissues is emphasized with the bold arrows on the labial surface of these restorations.

Orthodontic extrusion for implant site development revisited 223remaining clinical crown (tooth preparation) sothat it can be accommodated into the provi-sional. Modications to the internal surface ofthe provisional restoration need to be made sothat the prepared tooth has sufcient internalclearance during tooth movement. Lastly, ameans of generating adequate force from theprovisional to the tooth to be moved, typically anelastic thread (0.025 in.), can be used with a lightforce of less than 80 g. This will provide move-ments of 12 mm per month. Frequently, pro-phylactic endodontic therapy is performed toeliminate the potential for pulp exposure duringtooth reduction and to allow preparationthrough the clinical crown for elastic ligation aspreviously described.Figure 29. The images from left to right show a series of stimmediate implant provisional crowns at the time of implanprole in the subgingival area tissues is emphasized.panying diagram (Fig. 19B). Note that when theforce application can be applied from the centerof the crown in a coronal direction, the forcevector can be applied through the center-of-resistance of the tooth. This biomechanicalmodel demonstrates bodily movement throughpure translation in an occlusal direction.Therefore, the use of a provisional restorationprovides a means to avoid creating the forwardclockwise moment typically found when xedfacial brackets are used.

Awareness of the aforementioned principlesenables clinicians to understand the subtle butcritical differences between conventional toothmovement and orthodontic extrusion. Thisknowledge and the proper application of aeps required in the fabrication of a properly contouredt placement. The development of a proper emergence

variety of innovative techniques will yield greatpredictability of functional and esthetic results.

Case presentation

A 48-year-old male patient with an unremarkablemedical history presented for comprehensivedental treatment. A periodontal diagnosis oflocalized moderate to severe periodontitis withlocalized horizontal bone loss and moderate tosevere (localized) gingival recession was notedon the maxillary central incisors (Fig. 20). Thepatient's chief complaint was I have a large spacebetween my front teeth and these teeth feelloose. Radiographic evaluation revealed 4050% bone loss of teeth numbers 8 and 9(Fig. 21). Clinical exam revealed localizedprobing depths of 5 mm with 34 mm of

however, this did not address the patient's chiefcomplaint that included the loss of theinterdental papilla. In addition to the estheticconcern, the black triangle led to difculty inspeaking and food entrapment. After carefulinterdisciplinary analysis, a treatment alternativedesigned to correct this deciency was proposedto the patient. Orthodontic extrusion leading toextraction of numbers 8 and 9 would be used forrepositioning the interdental papilla and verticalbone growth with the anticipation of placementof dental implants at these sites (Figs. 2224).

CBCT revealed the faciallingual thickness ofbone would be insufcient to accommodate theappropriate size of implants. To meet this chal-lenge, and with the knowledge of the bio-mechanical principles already discussed, aninnovative approach was proposed to augment

resne

Controlled facial orthodontic extrusion in combinationingth

Hochman et al224development to the gingival tissues and the underlyOrthodontic extrusion represents a reliable option forgingival recession on the facial aspect of theseteeth. This patient was diagnosed as a Type Iattachment in which MGJ is attached to theperiosteum and the attached gingiva isconnected to the root surface. Mobility wasscored as Class II according to the Miller scale.These teeth had previous endodontic therapy asa result of severe root sensitivity. Cone beamcomputer tomography (CBCT) suggested a lackof the facial cortical plate of bone on these teeth(Fig. 21). Pertinent cephalometric informationincluded Steiner analysis, an incisal angle of 1251,and an interincisal angle of 971. Multipletreatment options were proposed. Onetreatment option was closure of the diastemawith conventional xed orthodontic appliances;

Figure 30. Clinical view of the nal implant supporteddemonstrates the presence of a facial cortical plate of bothe recipient implant site. Owing to the axialinclination of these teeth and the local anatomyof the pre-maxilla of this patient, the authorsproposed that applying an excessive forwardclockwise moment to the apex of teeth numbers8 and 9 would cause the roots to be labial to thefacial plate of bone. The authors term thistechnique controlled facial extrusion denedas a variant of orthodontic extrusion in which acontrolled facial (forward clockwise) moment isemployed to allow bone apposition along thepalatal aspect of the root thereby regaining thelost facialpalatal dimension of the alveolar ridge(Fig. 25). This deliberate controlled movementwould result in orthodontically facilitated bonedeposition along the root surface resulting from

torations at the 1-year follow-up visit on the left. CBCTon the surface of implant numbers 8 and 9 on the right.with vertical extrusion provided effective implant sitesupporting bone simultaneously and non-surgically.e multidisciplinary patient.

and time must be explained to the patient.

Orthodontic extrusion for implant site development revisited 225the tension along the entire surface of the palatalaspect of these teeth during movement. As descri-bed previously, the surface tension promotesbone apposition along the entire front of theseteeth as they are moved away from the bone in afacialocclusal direction. The reformation of anadequate thickness of the alveolar ridge usingorthodontic facial and vertical extrusion is aunique method of movement. Additionally, thecontrolled facial and vertical orthodonticextrusion technique would result in an incre-ase in the width of attached gingiva and thereformation of the interdental papilla betweenteeth numbers 8 and 9 fullling the secondtreatment objective of using this technique. Itbears repeating that this technique is performedwith the nal goal of removing the teeth andplacing immediate post-extraction socketimplants after the completion and stabilization oforthodontic movement.

The patient had active tooth movement over aperiod of 12 months. Once the adequatedimension of alveolar bone was conrmed via asubsequent CBCT, the teeth were held in thisposition for an additional 46 months to allowtime for bone maturation. Soft tissue reposi-tioning and the reformation of the lost inter-dental papilla is noted in Fig. 23. Immediate post-extraction socket implant placement was per-formed at the time of the removal of teethnumbers 8 and 9 (Fig. 26). The extractions wereperformed with a minimally invasive approachdened as a apless technique usingperiotomes and forceps. The biologic rationalefor a apless technique relates to preserving thesupracrestal bers and soft tissues that have beenestablished during tooth movement; additionally,the apless approach preserves a critical bloodsupply for the newly reformed bone.

Delayed implant placement after the extrac-tion of these teeth is contraindicated. Theauthors have observed two undesirable outcomeswhen delayed implant placement is utilized aftertooth removal: (1) the newly formed orthodon-tically facilitated bone will resorb if direct phys-ical bone stimulation is not maintained and (2)the gingival tissues will undergo remodeling aftertooth removal, with a loss of height and thickness.The immediate placement of dental implantsinto the matured alveolar ridge after 46 monthsof stabilization provides a favorable environmentfor long-term preservation of the reformed bonePatients are typically seen every 34 weeks duringthe active phase of tooth movement. Theseappointments are used to re-activate the forceapplied to the teeth. If a provisional restoration isto be used as the appliance for tooth movement,time must be allotted to remove the cementedprovisional, re-activate the appliance, and re-cement the provisional restoration. Theserepeated visits require signicant chair-time forand soft tissues. In addition to immediate implantplacement into the regenerated sites, fabricationof properly contoured immediate implant pro-visional crowns is a critical component to thepreservation of the soft tissue gingival contour(Figs. 2729). The proper restorative contourscreated by the provisional restorations weretransitioned to the denitive ceramo-metalrestorations (Fig. 30).

Discussion

The technique of orthodontic extrusion has beenutilized for a variety of applications in dentistrysince it was rst described over 40 years ago.6,7

The initial use of this technique demonstratedthat it could be used as a means of eliminatingperiodontal infrabony defects. Shortly thereafter,this same technique was used to orthodonticallyerupt fractured teeth so that a sufcientamount of clinical tooth structure would beavailable to restore a previously non-restorabletooth. The notion to use orthodontic extrusionto regenerate the interdental papilla has nowbecome routine procedure and is currentlyaccepted as the most predictable technique inthe reformation of the interdental pap-illa.4,5,16,17,22,23 More recently, the use of ortho-dontic extrusion as an effective tool in implantsite development has become an area of greatinterest, as this technique provides patients andclinicians with many advantages when comparedto surgical techniques.4,11,1225

There are several disadvantages of usingorthodontic extrusion as a therapeutic form oftreatment. During vertical tooth movement,occlusal interferences and contact to the oppos-ing arch must be eliminated. This often requiressubstantial tooth reduction, which can causesensitivity and/or pulp exposure, requiring pro-phylactic endodontic therapy (even if these teethwill eventually be extracted). The additional cost

extrusion will improve the nal esthetic-

development by orthodontic forced extraction: a prelimi-nary study. Int J Oral Maxillofac Implants. 2012;27:411420.

Hochman et al226each visit to accomplish. The total treatment timerequire to perform these procedures may be 918months, and the duration of treatment is deter-mined by severity of the tissue deciency and thecomplexity of the tooth movement required.Additional time for a retention phase of treat-ment must be added to the active treatment time,and this is typically not needed in other treatmentmodalities. One must weigh these disadvantagesagainst the unique advantages that orthodonticextrusion offers.

This article highlights several important ana-tomical considerations and biomechanical prin-ciples affecting orthodontic extrusion, not foundin the current literature. A novel technique,controlled facial extrusion combined with verti-cal eruption, was dened and described as amethod to augment the facialpalatal widthdimension of bone. The authors have sought tocall attention to the potential of producingunwanted outcomes from poorly controlledforces that occur and are unique to the estheticzone. The anatomy of the pre-maxilla, theangulation of anterior teeth, and the thickness ofthe facial alveolar bone are paramount factors totake into account when designing the ortho-dontic appliance to be used for forced eruption.As with all orthodontic interventions, gingivalhealth also plays a crucial role in a successfuloutcome. A discussion of biomechanical vectorsand moments that occur during forced eruptionaddressed how this particular type of toothmovement markedly differs from conventionaltooth movements. Understanding and address-ing these differences will ensure the desiredoutcome can be achieved. The importance oftorque control was discussed, and several sol-utions were offered to counteract the forwardclockwise rotational moment that is generated byextrusive forces.

Not to be overlooked is the fact that thesequence, timing, and technique of extraction ofteeth and implant placement after orthodonticextrusion can greatly affect the nal outcome.Stabilization after active tooth movement duringorthodontic extrusion has been recommendedfor a minimum period of 46 months to allowbone maturation and further ossication.A minimally invasive non-surgical apless toothremoval should be followed by the immediateimplant placement of dental implants afterorthodontic site development. This is concurrent5. Chou YH, Du JK, Chou ST, et al. An interdisciplinarytreatment approach combining orthodontic forced erup-tion with immediate implant placement to achieve asatisfactory treatment outcome: a case report. Clin ImplantDent Relat Res. 2013;15:113120.

6. Reitan K. Some factors determining the evaluation offorces in orthodontics. Am J Orthod. 1957;43:3245.restorative implant outcome in some of themost esthetically challenging clinical situations.Orthodontic extrusion is often the only modalitythat will achieve the optimal esthetic and func-tional outcome where there is extensive loss of softand hard tissues in the esthetic zone. Masteringthe techniques of orthodontic extrusion is aninvaluable addition to the interdisciplinary prac-tice because they offer predictable results forclinicians and patients alike.

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Conclusion

Orthodontic extrusion is a treatment alternativewith multiple benets that are not easily dupli-cated with other more invasive forms of treat-ment. Among these are the ability to predictablyregenerate osseous and soft tissues, eliminateinfrabony defects, improve the crown-to-root ratioof compromised teeth, convert a non-restorabletooth into a restorable tooth, and the use of ahopeless tooth for effective site development forimplant treatment. The use of orthodontic

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Orthodontic extrusion for implant site development revisited: A new classification determined by anatomy and clinical...IntroductionPrinciples of orthodontic extrusionPeriodontal gingival response to orthodontic extrusionClassification of soft tissue response to orthodontic extrusionType 1: Increase of width of attached gingiva and overall soft tissue width.Type 2: Increase of overall soft tissue width with no effect on the width of attached gingiva.Type 3: Width of attached gingiva and overall width of soft tissue are unchanged.

Principles of orthodontic extrusionBiomechanics

Anatomic considerations in the esthetic zoneCase presentationDiscussionConclusionReferences