CASE REPORT

Bimaxillary protrusion with an atrophic alveolardefect: Orthodontics, autogenous chin-blockgraft, soft tissue augmentation, and an implant

Grace S. C. Chiu,a Chris H. N. Chang,b and W. Eugene Robertsc

HsinChu City, Taiwan, Indianapolis, Ind, and Loma Linda, Calif

aLectubDireccProfeUniveneerinInd; vLindaAll auPotenAddreDr, InSubm0889-Copyrhttp:/

Bimaxillary protrusion in a 28-year-old woman was complicated by multiple missing, restoratively compromised,or hopeless teeth. The maxillary right central incisor had a history of avulsion and replantation that subsequentlyevolved into generalized external root resorption with Class III mobility and severe loss of the supporting perio-dontium. This complex malocclusion had a discrepancy index of 21, and 8 additional points were scored for theatrophic dental implant site (maxillary right central incisor). The comprehensive treatment plan included extrac-tion of 4 teeth (both maxillary first premolars, the maxillary right central incisor, and the mandibular right firstmolar), orthodontic closure of all spaces except for the future implant site (maxillary right central incisor),augmentation of the alveolar defect with an autogenous chin-block graft, enhancement of the gingival biotypewith a connective tissue graft, and an implant-supported prosthesis. Orthodontists must understand the limita-tions of bone grafts. Augmented alveolar defects are slow to completely turn over to living bone, so they are usu-ally good sites for implants but respond poorly to orthodontic space closure. However, postsurgical orthodontictreatment is often indicated to optimally finish the esthetic zone before placing the final prosthesis. The latter waseffectively performed for this patient, resulting in a total treatment time of about 36 months for comprehensiveinterdisciplinary care. An excellent functional and esthetic result was achieved. (Am J Orthod DentofacialOrthop 2015;147:97-113)

Orthodontists require a broad interactive knowl-edge of interdisciplinary care to manage partiallyedentulous malocclusions and may be the

appropriate clinicians to head the interdisciplinaryteam. Failing teeth and alveolar defects in the maxillaryesthetic zone are particularly challenging diagnosticproblems.1-5 One of the more perplexing challengesis the subsequent orthodontic treatment of teeth witha history of trauma. These teeth may fail before,during, or after orthodontic treatment. A history ofincisor avulsion and replantation is often associatedwith a compromised long-term prognosis.6,7 The

rer, Newton Implant Center, HsinChu City, Taiwan.tor, Beethoven Orthodontic Center, HsinChu City, Taiwan.ssor emeritus, Department of Orthodontics, School of Dentistry, Indianarsity, Indianapolis, Ind; adjunct professor, Department of Mechanical Engi-g, Indiana University and Purdue University at Indianapolis, Indianapolis,isiting professor, Department of Orthodontics, School of Dentistry, LomaUniversity, Loma Linda, Calif.thors have completed and submitted the ICMJE Form for Disclosure oftial Conflicts of Interest, and none were reported.ss correspondence to:W. Eugene Roberts, Indiana University, 8260 Skipjackdianapolis, IN 46236; e-mail, werobert@iu.edu.itted, June 2014; revised and accepted, August 2014.5406/$36.00ight � 2015 by the American Association of Orthodontists./dx.doi.org/10.1016/j.ajodo.2014.08.021

consequences of tooth avulsion are directly related tothe severity of the injury, the surface area of theinflamed root surface, the damaged root surface thatmust be repaired, and the treatment rendered at thetime of injury.1 Donaldson and Kinirons2 found thatperiodontal ligament “dry time” is the most crucial clin-ical factor associated with the development of subse-quent root resorption. If the periodontal ligament isleft attached to the root surface and does not dry outfor longer than 15 minutes, the probability of severeroot resorption is minimal. Appropriate pulp therapycan also minimize or prevent inflammatory root resorp-tion. Gregg and Boyd3 and Kinirons et al4 suggested thata replanted tooth with a closed apex should be endodon-tically treated as soon as the tooth has achievedadequate stability, ideally within 10 days after thetrauma. When pulp extirpation is delayed for morethan 20 days, the incidence of inflammatory resorptionincreases.4 For a tooth with a wide-open apex, endodon-tic treatment may be delayed because revascularizationof the pulp is possible, but the patient should be care-fully followed for inflammatory resorption.5

Despite advances in managing traumatically avulsedteeth, severe cervical and root resorption is common,with a reported prevalence of 57% to 80%.2,6,7

97

Fig 1. Pretreatment facial and intraoral photographs.

98 Chiu, Chang, and Roberts

Extensive resorption can compromise not only the toothbut also its supporting periodontium. This case reportpresents a 28-year-old woman with a chief complaintof poor esthetics and function, related to a hopeless(previously avulsed and replanted) maxillary centralincisor, missing or compromised mandibular first molars,and bimaxillary protrusion (Fig 1). Prescribing and per-forming appropriate interdisciplinary treatment requiredthe orthodontist (C.H.N.C.) to have a thorough knowl-edge of all aspects of the necessary interdisciplinarycare, as well as the relevant basic science. Because ofthe dynamic nature of the interactive treatmentrequired, the orthodontist led the interdisciplinary team.

Fig 2. The maxillary right central incisor had Class IIImobility and marked hard and soft tissue deficiencies. Aperiapical radiograph shows external root resorptionand severe loss of periodontal support.

DIAGNOSIS AND ETIOLOGY

A 28-year-old woman sought consultation for amutilated bimaxillary protrusion complicated by a

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Fig 3. Pretreatment dental models.

Fig 4. Pretreatment cephalometric radiograph.

Table. Cephalometric summary

Pretreatment Posttreatment DifferenceSkeletal analysisSNA (�) 87 87 0SNB (�) 83 83 0ANB (�) 4 4 0SN-MP (�) 29 29 0FMA (�) 22 22 0

Dental analysisU1-NA (mm) 10 6 4U1-SN (�) 120 113 7L1-NB (mm) 13 9 4L1-MP (�) 105 102 3

Facial analysisE-line-upper lip (mm) 5 3 2E-line-lower lip (mm) 5.5 4.5 1

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failing maxillary right central incisor with a severe labialcleft and Class III mobility (Fig 2). There was an etiologyof trauma at about 9 years of age, when the tooth wasavulsed and replanted. This is a common but highly var-iable problem affecting up to 16% of children.1-7 Thepatient reported that the replanted tooth healeduneventfully, but there was no follow-up pulp evalua-tion. The tooth remained asymptomatic until mobility

American Journal of Orthodontics and Dentofacial Orthoped

was first noted about 5 years previously (age 23 years).Mobility and soft tissue recession had progressivelyincreased since that time.

Clinical and radiographic evaluation of the maxillaryright central incisor showed extensive external rootresorption (.80% of the root surface), an enlargedpulp chamber, and severe loss of periodontal support(Fig 2). In the mandibular arch, the left first molar was

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Fig 5. Pretreatment panoramic radiograph.

Fig 6. The maxillary right central incisor was extracted,and the crown portion was prepared to serve as a spacemaintainer for the implant site.

Fig 7. Class II elastics were used to close the extractionspaces in both arches and retract the maxillary anteriorsegment.

Fig 8. Lingual buttons and power chains were used tofacilitate space closure and prevent rotations.

Fig 9. The bracket on the lower left second premolar wasrepositioned twice to correct the mesial rotation.

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missing, the left second molar was mesially tipped, andthe right first molar was endodontically treated andwas temporarily restored with amalgam (Fig 1). The pre-treatment study casts showed that the patient had anexcessive overjet of about 4 mm and a space deficiencyin the maxillary arch of about 5mm (Fig 3). The pretreat-ment cephalometric analysis was consistent with a ClassI skeletal pattern, a convex profile, bimaxillary protru-sion, and excessive axial inclination of the maxillary

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and mandibular incisors (Fig 4, Table). The panoramicradiograph showed that all third molars were presentand fully erupted (Fig 5). The American Board of Ortho-dontics (ABO) discrepancy index8 was 21 points, asshown in the Supplementary Discrepancy Index(Worksheet 1). The compromised implant site (maxillaryright central incisor) scored an additional 8 points for

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Fig 10. Extra-alveolar miniscrews were placed in the mandibular buccal shelves to retract the mandib-ular arch and create an overjet to permit retraction of the maxillary anterior segment.

Fig 11. All posterior spaces were closed, and the roots ofthe teeth were well aligned. Fig 12. Severe horizontal and vertical ridge deficiencies

in the edentulous area of the maxillary right centralincisor.

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complexity (form in Worksheet 1). Overall, this mutilatedmalocclusion (Figs 1-3) was a severe problem requiring acarefully sequenced, interdisciplinary approach.

TREATMENT OBJECTIVES

The following treatment objectives were determined.

1. Maintain the dimensions of all 3 skeletal planes inboth the maxilla and the mandible.

2. Extract both maxillary first premolars, the hopelessmaxillary right central incisor, and the compromisedmandibular right first molar.

3. Use full fixed orthodontic therapy to relieve crowd-ing, retract the anterior segments to correct the bi-maxillary protrusion, and close all spaces except themaxillary right central incisor implant site.

4. Surgically repair the atrophic maxillary right centralincisor alveolar defect with an autogenous chin-block graft and correct the thin gingival biotypewith connective tissue grafts.

5. Use an implant-supported prosthesis to restore themaxillary right central incisor.

6. Optimize dentofacial esthetics with orthodontictreatment and soft tissue detailing.

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TREATMENT ALTERNATIVES

A common option for correcting bimaxillary protru-sion is extraction of all 4 first premolars. However, thispatient had missing and compromised mandibular firstmolars, so the appropriate extraction sequence wasmaxillary first premolars and mandibular first molars.This approach presented anchorage problems that weremanageable with advance planning.

Omitting the bone graft and closing the space for theextracted maxillary right central incisor (Fig 2) may be anattractive orthodontic option, but that approach wouldcreate extensive restorative problems to scale the incisorsand prevent an end-on occlusion, which would likelyresult in compromised dental esthetics in the criticalmaxillary anterior area. A fixed partial denture to replacethe maxillary right central incisor was not a viable alterna-tive because it would require preparing adjacent virginteeth. The patient rejected space closure and a fixed partialdenture in favor of augmenting the soft and hard tissuedefects and restoring with an implant-supported crown.When selecting this option, the patient was informedthat it was a complex treatment plan with many stepsthat might or might not be completely successful. Also,

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Fig 13. Clinical procedures of harvesting the corticocancellous chin-block graft: A, the recipient site isprepared to receive a cortical block graft; B, partial-thickness flap originating in the attached gingivaextends into a full-thickness flap to denude bone in the chin area; C, bone graft block is sectionedwith a bur;D, the autogenous graft is fractured loose from the cortical plate; E, soft tissue is closed afterremoving the bone block; F, frontal view shows bone graft secured with 2 stainless steel screws;G, occlusal view shows the bone grafted area; H, grafted area is covered with freeze-dried demineral-ized bone particles and enclosed with a collagen membrane (below); I, the maxillary anterior soft tissueis closed with interrupted sutures.

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follow-up orthodontic treatment might be necessary forfinal detailing. After considering the pros and cons ofeach option, the patient exercised her informed consentby selecting bone and soft tissue augmentation followedby an implant-supported prosthesis.

TREATMENT PROGRESS

After the maxillary right central incisor, both maxil-lary premolars, and the mandibular right first molarwere extracted, a mixed 0.022-in fixed appliance wasbonded on all teeth using ICE clear fixed brackets(Ormco, Glendora, Calif) in the anterior segments. After

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extraction, the crown portion of the maxillary centralincisor was prepared as a pontic and bonded with anICE bracket to provide natural esthetics and space main-tenance during active orthodontic treatment (Fig 6).The archwire sequence in both arches was 0.016-innickel-titanium, 0.016 3 0;0.022-in nickel-titanium,and 0.016 3 0;0.022-in stainless steel. Class II elasticswere used to close the posterior extraction spaces andretract the maxillary anterior segment (Fig 7). Lingualbuttons were bonded on the mandibular rightsecond molar and first premolar, and the mandibularleft first premolar and second molar; lingual powerchains were applied to help close the spaces (Fig 8).

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Fig 14. Four months after the autogenous chin-block augmentation (A), the ridge in the implant sitehad sufficient width and height (B). The acrylic surgical stent (C and D) is fitted to serve as a guidefor implant placement. The ideal free gingival margin is 1 mm apical to the margin of the surgical stentin the edentulous area (C).

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Balancing buccal and lingual force can facilitate spaceclosure and help prevent molar tipping and rotation.9

The mandibular left second premolar was mesiallyrotated about 80�, so it was necessary to rebond thebracket twice during treatment to correct the alignment(Fig 9).

After 21 months of active treatment, all mandibulararch spaces were closed, but extraction spaces remainedin the maxillary arch. Extra-alveolar miniscrews wereplaced in the mandibular buccal shelves to retract theentire dentition.10,11 Once a positive overjet wasachieved, maxillary elastomeric chains were used toclose the residual space by retracting the anteriorsegment (Fig 10).

After 25 months of treatment, all spaces were closedexcept for the maxillary right central incisor implant site(Fig 11). All fixed appliances were removed, and reten-tion was accomplished with a maxillary clear overlayand a mandibular fixed retainer.

The edentulous anterior ridge (area of the maxillaryright central incisor) had severe horizontal and verticaldeficiencies (Fig 12). To repair the defect, an autoge-nous bone block was harvested from the chin area.This is a common donor site for reconstructing severeridge defects, but the method requires a precise surgicaltechnique, as will be described, illustrated, anddiscussed.

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Intrasulcular incisions were made from the maxillaryright canine to the left lateral incisor with a number 15cscalpel blade, and a full-thickness flap was reflected.Decortication of the alveolar bone was performed witha small high-speed round bur to expose the bonemarrow space, accelerate revascularization, and increasethe regional acceleratory phenomena.12,13 The recipientsite was recontoured to improve the fit of the graft intothe defect (Fig 13, A).14

A horizontal incision was made with a number 15blade at the mucogingival junction from the mandibularleft canine to the right canine. Initially, the blade washeld at 45� to create a 5-mm partial-thickness reflectionand was then turned to 90� to cut a full-thickness flap.The 5-mm partial-thickness area allowed for a doublelayer of sutures when the flap was closed to help captureand stabilize a subperiosteal blood clot to facilitatewound healing (Fig 13, B).

The autogenous chin block was harvested with afissure bur in a surgical hand piece. The fissure burwas used to cut through the cortex and outline the donorsite (Fig 13, C). Then a straight bone chisel was insertedinto the cut and gently tapped with a mallet to free thecortical bone block and elevate it (Fig 13, D). The har-vested area followed the “5-mm rule,” which meansthat all operated areas are at least 5 mm from incisorapices, the mental foramen, and the mandibular

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Fig 15. Soft tissue is reflected (A) to expose the healed bone graft (B). The surgical stent is designed toposition the osteotomy for the implant in the frontal (C) and occlusal (D) planes. A portion of the chin-block graft is still visible on the facial aspect of the implant (E and F).

Fig 16. After an unloaded healing phase, a 4/5mmpunchwas used to access the implant. A temporaryrestoration was then fabricated.

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border.14 The depth of the osteotomy depends on thethickness of bone required by the recipient site, but itshould not be over half of the thickness of the mandib-ular symphysis.

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Bone wax was packed into the donor site to controlbleeding after the chin block was harvested. A double-layer suture technique was used. The first layer was 5-0 chromic gut suture used to attach the inner surface

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Fig 17. Flowable resin was added to the subgingival part of the temporary restoration tomold an appro-priate emergence profile.

Fig 18. A andB,A partial-thickness flapwas reflected, and a connective tissue graft was placed.C andD, A second connective tissue graft was placed to further augment the site.

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of the flap to the periosteum in the 5-mm partial-thickness area. The second layer was 5-0 Vicryl (Ethicon,Somerville, NJ) to suture the outer flap to the keratinizedtissue bordering the donor area (Fig 13, E).

The harvested corticocancellous bone block wastrimmed carefully to fit into the recipient site. The inti-mate contact of the graft to the recipient site improvesblood supply and helps integration. Two screws wereused to fix the bone block and prevent rotation(Fig 13, F and G). The residual gaps were filled with par-ticulate freeze-dried bone allograft and covered with acollagen membrane (Fig 13, H). The wound was closedwith a tension-free flap and secured with Gore-Tex su-tures (Gore Medical, Flagstaff, Ariz) (Fig 13, I).

American Journal of Orthodontics and Dentofacial Orthoped

Four months after the autogenous chin-blockaugmentation, the ridge had healed with adequate widthand height to accommodate an implant. An acrylic sur-gical stent was used to properly position the fixture. Thestent was designed with a labial border about 1 mmshort of the desired mucogingival junction. It providedan anatomic reference for placing the implant in anoptimal position relative to the supporting bone andattached gingiva (Fig 14).

For implant placement, an intrasulcular incision wasmade from the maxillary right canine to the left lateralincisor with a number 15c blade; a full-thickness flapwas reflected, and the bone graft fixation screws wereremoved (Fig 15,A and B). The bone crest was measured

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Fig 19. Placement of 2 connective tissue grafts caused toomuch tension on the labial flap, opening thewound. The area achieved secondary healing, but some scar tissues were formed. From left to right,the postoperative course is shown at 1, 2, 3, and 4 weeks.

Fig 20. Electrosurgery was used to remove scar tissue, and brackets were replaced to achieve finalalignment of the maxillary anterior segment.

Fig 21. After removing the temporary prosthesis, the soft tissue profile developed by the temporarycrown was visible. It was imperative to keep this profile and transfer it exactly to the permanent pros-thesis.

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to be about 4 mm from the cervical contour of the sur-gical stent (Fig 15, C). According to the “2B-3D rule,” theideal vertical position of the implant is about 3 mm fromthe predetermined free gingival margin to the implantplatform.15 The 4-mm stent to bone distance was idealbecause the stent was about 1 mm short of the plannedfree gingival margin. A guiding pin was used after the pi-lot drill to check the path of insertion. From the mesio-distal aspect, the implant should be parallel with theadjacent roots; from the buccopalatal aspect, theimplant should be positioned between the incisal edgeand the cingulum (Fig 15, D). After the path of insertionwas confirmed with a periapical film, the osteotomy site

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was prepared according to standard protocols, and theimplant was inserted. Figure 15, E and F, shows thatthe implant is in an optimal position. A portion of thechin-block graft is still visible on the facial aspect ofthe implant.

After a 4-month unloaded healing phase, the implantwas uncovered, and a temporary restoration was fabri-cated. Since there was sufficient keratinized gingiva onthe buccal surface, a punch (inner diameter, 4 mm; outerdiameter, 5 mm) was used to access the implant insteadof raising a flap. A temporary abutment was preparedand attached. A prefabricated temporary crown was re-lined and then connected to the abutment (Fig 16).

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Fig 22. The sequential clinical procedure is shown for making a customized impression post. After softtissue molding, the temporary crown (A) is fitted to an analog and inserted into a cylinder filled withimpression material (B and C). After the material sets, the crown is unscrewed from the implant analogto reveal the soft tissue contour. A stock impression post (E) is screwed into the analog (F), resin isflowed in to fill the open space and then polymerized (G), and the customized impression post (H) isremoved from the mold. The customized impression post is fitted in the mouth and a final impressionis made (I and J), and the permanent crown is fitted to the abutment (K and L).

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The desired subgingival contour was added with flow-able resin to mimic a natural emergence profile (Fig17). The purpose of this customized temporary restora-tion was to guide the soft tissue healing and create anatural gingival contour.

After the temporary restoration was finalized, a softtissue augmentation procedure was indicated toenhance the thin soft tissue biotype. A partial-thickness flap was reflected, and a connective tissuegraft from the right side of the palate was harvested toaugment the buccal soft tissue (Fig 18, A and B). Afterthe first connective tissue graft was placed, the recipientsite was still concave, so a second connective tissue graftfrom the left side of the palate was harvested to supple-ment the augmentation site (Fig 18, C andD) to producea more esthetic rounded contour.

However, placement of 2 connective tissue graftsstrained the buccal flap closure, and the wound openedduring the healing phase. The area achieved secondaryhealing, but scar tissue was created on the facial surface(Fig 19). Electrosurgery was used 6 weeks after surgeryto cauterize and remove as much scar tissue as possible.To achieve an ideal result, additional orthodontic treat-ment was indicated, so brackets were placed on the

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maxillary arch to further refine the positioning of theteeth in the esthetic zone (Fig 20).

Three months later, the soft tissue had healed, andthe desired orthodontic finish was achieved. Impressionswere made for permanent prosthesis fabrication. Whenthe temporary prosthesis was removed, an optimalperi-implant soft tissue profile was evident (Fig 21). Itwas imperative to transfer this soft tissue relationshipwith a customized impression post.16

The temporary prosthesis was removed and con-nected to an implant analog. It was stabilized in a rubbercup, and bite registration material was injected to coverthe subgingival area of the temporary prosthesis. Oncethe material was set, the temporary crown was removed,and the subgingival soft tissue contour, registered bybite registration materials, was visible (Fig 22, D). Theimpression post was connected to the analog, and theresidual gap was filled with flowable resin (Fig 22, G).The customized impression post, which recorded theexact subgingival contour of the prosthesis (Fig 22, H),was placed back in the mouth to facilitate the finalimpression. Subsequently, the permanent prosthesiswas fabricated, and the restoration was completed(Fig 22, K and L).

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Fig 23. Posttreatment facial and intraoral photographs.

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TREATMENT RESULTS

The posttreatment photographs showed that facialesthetics was improved due to correction of the bimax-illary protrusion (Fig 23). Both maxillary and mandibularanterior segments were retracted, and all mandibularspaces were closed (Fig 24). Since the premolars wereextracted in the maxilla but not in the mandibulararch, the occlusion was finished in a molar Class II rela-tionship (Fig 25). The ABO cast-radiograph evaluationscore (Supplementary Cast-Radiograph Evaluation[Worksheet 2]) was 13 points.17 Much of this excellentscore reflected the follow-up orthodontic treatmentbefore fabricating the final prosthesis.

With regard to the implant site, there were some scartissue on the facial surface and a small dark triangle(insufficient papilla) on the distal aspect. These 2 prob-lems resulted in a pink and white esthetic score of 2(Supplementary IBOI Pink & White Esthetic Score[Worksheet 3]).18 Overall, the tissue augmentation

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procedures and the temporary restoration moldingmethod were successful. The frontal view was pleasing,and the buccal prominence of the ridge was satisfactoryas assessed from the occlusal view (Fig 26). The patientwas happy with the final result.

DISCUSSION

When closing spaces to correct a bimaxillary protru-sion, attention must be paid to the progress of spaceclosure relative to anchorage control in all 4 quadrants.If space closure in one segment is more rapid than inanother, it may be necessary to adjust the applied me-chanics or supplement the anchorage. For our patient,Class II elastics were used initially as the mechanics inthe sagittal plane to close the posterior spaces in botharches. Space closures progressed more rapidly in themandibular arch compared with the maxillary arch. Re-assessment produced the following treatment planchanges: (1) power chains in the maxillary arch to retract

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Fig 24. Posttreatment dental models.

Chiu, Chang, and Roberts 109

the anterior dentition and (2) miniscrews placed in themandibular buccal shelf areas to retract the entiremandibular dentition (Fig 10).10,11 These changes inmechanics limited the side effects of the Class IIelastics and enhanced the lip retraction to correct thebimaxillary protrusion (Fig 23).

For atrophic alveolar ridge augmentation, there aremany recommended approaches, including alloplasticbone substitutes, xenografts, allografts, and autoge-nous bone grafts. Bone grafts may contain bonemorphogenic proteins, which are purported to haveboth bone conductive and inductive effects.19 Autoge-nous bone grafts are the gold standard for alveolarridge augmentation and are classified as follows: (1)endochondral bone, such as iliac crest and long bones;and (2) intramembranous bone, such as mandibularramus and symphysis. Kusiak et al20 found that intra-membraneous (also called membraneous) bone graftsshow earlier revascularization than endochondral boneblocks. Enhanced invasion of blood vessels promotesbone modeling and remodeling of the nonvital bonegraft. Autogenous chin grafts are from bone that is in-tramembranous in origin. This bone graft showed good

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volume and stability, and it achieved primary unionwith the host bone.

Vascular invasion with activated pericytes (Fig 27) isthe initial step for the induction of new bone forma-tion.21,22 When angiogenesis begins, the capillariesstart growing through a budding process, and thepericytes propagate to produce more pericytes for thenew vascular buds (Fig 28).21 The pericytes are osteo-genic precursor cells that migrate from the perivascularregion to form osteoblasts (Fig 29).21 The multipotentpericytes are then chemically stimulated by growth fac-tors released from the wound area to differentiate intoosteoblasts.22 Therefore, the early revascularization ofan autogenous bone graft accelerates the de novobone formation that is essential for bone graft integra-tion. An allograft or a xenograft usually requires at least6 months to form substantial amounts of living bone inthe grafted area. Autogenous bone blocks require onlyabout 4 months to adequately heal, stabilize, andremodel because of an earlier revascularization effect.Thus, autogenous bone blocks can shorten the healingtime before an implant is placed, thereby acceleratingthe overall progress of treatment.

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Fig 25. Cephalometric tracings superimposed on the anterior cranial base, maxilla, and mandible.Black, pretreatment; red, posttreatment.

Fig 26. Final result for the implant-supported prosthesis replacing the maxillary right central incisor.The buccal prominence of the alveolar ridge over the implant was satisfactory (right).

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It is important to realize that all cortical bone graftsare dead, dense bone that is slow to resorb andremodel to new living bone. Once the grafted (largelydead) cortical bone bonds with the host bone(Fig 15, F), it is a biocompatible material that is agood site for an implant. Dead bone can effectivelysupport an implant and continue to remodel normally.However, moving a tooth into a grafted site is a muchmore difficult problem because even a small amountof dead bone in the path of tooth movement precludeseffective orthodontic treatment. Consequently,grafted alveolar defects are usually good sites forimplants, and adjacent teeth can be detailed

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orthodontically, but space closure of a grafted defectis contraindicated.

Figure 15, F, shows that a portion of the chin-blockgraft was still visible on the buccal side of the implant;this demonstrates an important biologic principle forsites grafted with thick portions of cortical bone. Thechin block is a nonvital piece of cortical bone that is abiocompatible graft material because it is autogenous.When reopened for implant placement, previouslyaugmented alveolar defects are a mixture of vital andnonvital bone. A thick block of autogenous corticalbone resorbs slowly, but it can still provide adequatesupport for an implant and may be more stable for

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Fig 27. Activated pericytes are precursors for osteo-blasts.

Fig 28. Pericytes propagate along the surface of an elon-gated capillary sprout. (Permission to reuse obtainedfrom Chang et al.21)

Fig 29. Pericytes are stimulated by growth factors tomigrate away from blood vessels and differentiate into os-teoblasts.

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long-term resistance to labial recession than vital alve-olar bone.

There are some important details for enhancing thehealing of autogenous bone grafts. First is use of a small

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round bur to perforate the cortical bone and promotebleeding. Capturing a healthy blood clot within andaround the autogenous graft provides a natural sourceof growth factors to promote vascular invasion andosteogenesis. Site preparation induces a regional accel-eratory phenomenon that induces remodeling of thebone adjacent to the graft site. Frost12,13 described thepostoperative regional acceleratory phenomenon asenhanced remodeling of both soft and hard tissues inthat area. These effects usually start several days aftersurgery and maximize in 1 or 2 months after it. Insome cases, the regional acceleratory phenomenon canlast 6 to 24 months.23,24

When a chin graft is harvested, blood is often oozingfrom the marrow space; this can cause a hematoma orecchymosis (bruised spot) on the face. To minimize post-operative bleeding, bone wax is packed directly into theosseous wound to control the bleeding at the donor site.The hemostatic material Surgicel (Ethicon) is not recom-mended because it does not effectively control oozingfrom wounded bone.

When suturing the recipient site, 2 layers of sutures areused. The first layer is a resorbable suture, such as 5-0chromic gut, to reposition the mentalis muscle and peri-osteum back in their original positions. This is an impor-tant step to prevent ptosis (drooping) of the chin and lipincompetence.25 The second (more superficial) layer of5-0 sutures can be resorbable Vicryl or nonresorbableproducts such as Gore-Tex or nylon. The mucosa shouldbe carefully approximated to minimize scarring.

Patients may be concerned about a change in thechin profile after harvesting the chin block, but follow-up studies show that these concerns are unwarranted.Radiographs 6 months after the surgery show that the

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original bone contour has almost recovered, and after2 years the donor site is completely healed.26

Some patients may experience an altered sensation ofthe mandibular anterior teeth or lower lip, but the prob-lem is usually resolved within 6 to 12 months.27 As longas the harvested area is no closer than 5 mm to themental foramen and the root apices of the adjacentteeth, the chance of permanent damage to the anteriorloop of the mental nerve or teeth is minimal.28

Overall, the autogenous chin graft is a safe and effi-cient procedure for reconstructing severe ridge defects.Understanding the biologic principles and obeying thesafety rules minimize the chance of significant compli-cations. However, once a bone graft is placed in an alve-olar defect, the clinician has committed to a prostheticsolution to replace the tooth because the slow turnoverto viable bone precludes orthodontic space closure.

CONCLUSIONS

Adult orthodontic patients often have complex mal-occlusions complicated by periodontal and prosthodon-tic problems caused by hard and soft tissue deficiencies.An enlightened interdisciplinary approach usually givespatients the best results. Managing complex malocclu-sions in adults is challenging, but providing effectivetreatment for these difficult problems is quite rewarding.Clearly, orthodontic preparation of the edentulous area,as well as the adjacent and opposing teeth, often en-hances the final outcome. However, orthodontistsmust have a good understanding of all subsequent sur-gical and prosthetic procedures to provide an optimalservice.

An excellent clinical result was achieved, as docu-mented by a cast-radiograph evaluation score of 13(Supplementary Worksheet 2) and a pink and whitedental esthetics score of 2 (Supplementary Worksheet 3).

ACKNOWLEDGMENTS

We thank Hsin-Yin Yeh and Ming-Wei Wei forcorrection of the cephalometric tracings and Paul Headfor proofreading this article.

SUPPLEMENTARY DATA

Supplementary data related to this article can befound in the online version at http://dx.doi.org/10.1016/j.ajodo.2014.08.021.

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