Case Series

Endoscopically Assisted TunnelApproach for Minimally InvasiveCorticotomies: A Preliminary ReportFederico Hernandez-Alfaro*† and Raquel Guijarro-Martınez*

Background: The dental community has expressed low ac-ceptance of traditional corticotomy techniques for corticotomy-facilitated orthodontics. These procedures are time consuming,entail substantial postoperative morbidity and periodontal risks,and are often perceived as highly invasive.

Methods: A total of 114 interdental sites were treated in nineconsecutive patients. Under local anesthesia, a tunnel approachrequiring one to three vertical incisions per arch (depending onthe targeted teeth) was used. Piezosurgical corticotomies andelective bone augmentation procedures were performed underendoscopic assistance. Postoperative cone-beam computerizedtomography evaluation was used to confirm adequate corticoto-my depth.

Results: Procedures were completed in a mean time of 26minutes. Follow-up evaluations revealed no loss of tooth vitality,no changes in periodontal probing depth, good preservation ofthe papillae, and no gingival recession. No evidence of crestalbone height reduction or apical root resorption was detected.

Conclusions: The tunnel approach minimizes soft-tissue de-bridement and permits effective cortical cuts. The combinationof piezosurgery technique with endoscopic assistance providesa quick, reliable means to design and perform these corticoto-mies while maximizing root integrity preservation. Moreover,the sites needingboneaugmentation are selected under direct vi-sion. Compared to traditional corticotomies, this procedure hasmanifest advantages in surgical time, technical complexity, pa-tient morbidity, and periodontium preservation. J Periodontol2012;83:574-580.

KEY WORDS

Endoscopy; malocclusion; periodontium; orthodontics,corrective; osteotomy.

At present, the number of patientsseeking orthodontic treatmentduring adulthood to correct es-

thetic and occlusal aberrations is in-creasing significantly. Short treatmenttime is a constantly recurring request.However, conventional orthodontic ther-apy is associated with long treatmenttimes and potential risk of periodontaldeterioration and root-end resorption,especially in patients with a thin peri-odontal biotype. In addition, significantjaw discrepancy and the anatomic limitsset by the cortical plates of the alveolimay hinder orthodontic movement.1,2

Hence, clinicians have searched foralternative methods to accelerate toothmovement with the aid of segmentalosteotomies and corticotomies.1-9 How-ever, traditional techniques have oftenbeen considered rather invasive, leadingto low acceptance by patients and thedental community.10

Although some authors2,3,5,6,9 be-lieve that the rapid tooth movementobserved with corticotomy-facilitated or-thodontics is attributable to the move-ment of the small outlined blocks ofbone, others7,8,11-13 consider it is morelikely the consequence of a sequentialdemineralization–remineralization pro-cess. Based on computed tomographystudies, Wilcko et al.7,8 suggested an

* Institute of Maxillofacial Surgery, Teknon Medical Center, Barcelona, Spain.† Master Program in Implant Dentistry, International University of Catalonia, Barcelona,Spain.

doi: 10.1902/jop.2011.110233

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increase in cortical bone porosity and a dramatic in-crease of trabecular bone surface turnover consistentwith the initial phase of the regional acceleratory phe-nomenon (RAP). Described by orthopedist HaroldFrost,14,15 the RAP comprises a complex cascade ofphysiologic healing events involving acceleratedbone turnover and regional osteopenia. Surgicalwounding of cortical bone is followed by a transitoryburst of localized hard- and soft-tissue remodelingthat gives way to tissue reorganization and healing.16

In other words, according to the RAP theory, cortico-tomy-facilitated orthodontics would be more appro-priately portrayed as ‘‘bone matrix transportation’’rather than ‘‘bony block movement.’’8

As described in the scientific literature, traditionalcorticotomy techniques imply full-thickness flapelevation, corticotomy cuts, and elective bone graft-ing.2,7,8,17 These procedures are: 1) often time con-suming (3 to 4 hours according to some reports8),2) require oral and/or intravenous sedation,2,7,8 and3) lay down undeniable postoperative morbidity andperiodontal risks for the patient. Alternativeminimallyinvasive procedures are being developed with the aimof reducing surgical time and patient discomfort andincreasing periodontal safety and patient acceptabil-ity of the procedure.10,18 Sharing this objective, thepurpose of this article is to present a simple yet effec-tive technique to perform corticotomies through aminimally invasive approach with endoscopic assis-tance. The proposed procedure has manifest advan-tages in surgical time, technical complexity, patientmorbidity, and periodontium preservation.

CASE DESCRIPTION AND RESULTS

From March to July 2010, a minimally invasive tunneltechnique for corticotomieswas performed in nine con-secutive patients (four males and five females; medianage: 37 years; range: 22 to 46 years) at the Institute ofMaxillofacial Surgery and Implantology of the TeknonMedical Center (Barcelona, Spain). Specific written in-formed consent was obtained in all cases, and approvalfrom the TeknonMedical Center Review Board was ob-tained to perform the technique and report its results. Atotal of 114 interdental sites were treated. Indicationsfor the procedure included: 1) deep bite; 2) posteriorcross-bite; 3) open bite; and 4) anterior crowding.

Surgery was performed under local anesthesia in sixcases. In the remaining three patients, the procedurewas done together with another orthognathic surgeryprocedure in the context of a ‘‘surgery first’’ ap-proach,19 and thus general anesthesia was used.

A conjunct treatment plan was developed by theorthodontists (Drs. Jaume Janer, Ana Molina, NuriaClusellas, Elena Portugal, and Natalia Mateo, privatepractice in orthodontics, Barcelona, Spain; andDr. Blanca Loscertales, private practice in orthodon-

tics, Seville, Spain), periodontist (Dr. Vanessa Ruiz,Department of Periodontics, Institute ofMaxillofacialSurgery, Teknon Medical Center, Barcelona, Spain),and oral surgeon (FH-A). The following variables weredetermined: 1) teeth to be moved, 2) teeth to be usedas anchorage, 3) periodontal status, 4) root morphol-ogyandposition,and5)widthof thecorticalplates.Forthe last two items, cone-beam computerized tomogra-phy (CBCT)‡ was performed.

In all cases, local anesthesia (2% lidocaine with1:100,000 epinephrine) was infiltrated to reducebleeding and facilitate subperiosteal dissection ofthe flaps. A full-thickness (5 to 10 mm) vertical inci-sion was performed labially at the upper or lower mid-line (in cases in which the anterior teeth were to betreated) and/or behind the upper canine (when target-ing the posterior maxilla). A sharp periosteal elevatorallowed wide subperiosteal dissection over the rootsof the involved teeth. Care was taken not to damagethe potential anterior loopof the inferior alveolar nervethat could extend mesially from the mental foramen.Subsequently, a piezoelectric microsaw§ was intro-duced into the tunnel created underneath the flap. In-terproximal corticotomies were performed betweenthe dental roots following the long axis of the alveolusand stopping just short of the alveolar crest (Fig. 1).Endoscopic assistance through a 1.9-mm fiber opticendoscopei aided corticotomy design and control andallowed for in situ corroboration of a successful cutthrough the cortical bone (when the saw reachedthe spongiosa, bleeding was observed with the endo-scope) (Fig. 2). The microsaw encountered little re-sistance when cutting bone; resistance to the sawmeant the presence of underlying roots and hencea change in the direction of the cuts. The cuts were ex-tended through the entire thickness of the corticallayer and interrupted when penetrating the medullarybone. In one patient, interproximal corticotomieswere extended to the lingual cortical bone to achievea ‘‘box osteotomy.’’ No luxation maneuvers were per-formed after any of the osteotomies. Figure 3 showsthe complete sequence for a case in which the poste-rior maxilla was targeted.

An established augmentation procedure was per-formed in four patients in whom the preoperativeCBCT had revealed thin cortical plates and/or theendoscope had detected bone dehiscences (Fig. 2,arrow). In these cases, demineralized bovine boneparticles¶ were applied over the corticotomies viathe same approach. Finally, the incisions were su-tured with interrupted 5-0 polyglactin.#

‡ IS i-CAT v. 17-19, Imaging Sciences International, Hatfield, PA.§ Implant Center 2, Satelec-Acteon Group, Tuttlingen, Germany.i TrueView, Olympus, Munich, Germany.¶ Bio-Oss, Geistlich Pharma, Wolhusen, Switzerland.# VICRYL, Ethicon, Somerville, NJ.

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Mean surgical timewas26minutes (range: 14 to 32minutes). Postoperative CBCT evaluation to confirmadequate corticotomydepth revealed acomplete ves-tibular corticotomy in 102 interdental sites. In eightsites, a vestibular cortical cut was present but failedto reach the spongiosa. In the remaining four sites(corresponding to one patient), the corticotomy wasextended to the lingual cortical bone following the or-thodontist’s instructions (Fig. 4).

Patients were discharged within 2 hours of the pro-cedure. For patients in whom the corticotomies wereperformed together with another orthognathic sur-gery procedure under general anesthesia, hospitaldischarge was postponed 24 hours. Prophylactic

antibioticmedication was prescribed for 1week; rou-tine non-steroidal anti-inflammatory drugs wererestricted to the first 5 postoperative days so as toavoid interference with the RAP. In all cases, ortho-dontic treatment was resumed the day after surgery.Pulp vitality and probing depth (PD) were evaluatedin all the teeth involved in the procedure at least onceper month.

Postoperative follow-up detected dentinary hyper-sensibility in three teeth of one patient, but it resumedwithout complications after 5 weeks. No loss of toothvitality and no adverse periodontal effects wereclinically noticeable. Indeed, periodontal checkupsrevealed no changes in periodontal PD, good preser-vation of the interdental papillae, and no gingival re-cession (Fig. 5). Similarly, no significant reductionin crestal bone height and no evidence of apical rootresorption were detected by radiographic methodsduring 12 months of follow-up evaluations.

DISCUSSION

The key advantages of corticotomy-facilitated ortho-dontics compared to traditional orthodontics includeenhanced scope of malocclusion treatment with de-creased need for extractions, significantly reducedactive orthodontic treatment time (three-fold aver-age), and the possibility to restore alveolar volumeand periodontium integrity in a one-stage proce-dure.2,8,10 These progresses have led to an increasein the number of adult patientswho choose to undergoorthodontic treatment.

Traditional orthodontic movement can be ex-plained by a series of cell-mediated histologic andbiomolecular phenomena in the periodontal ligament

Figure 1.A) Labial full-thickness vertical incision at the upper midline. Theanterior teeth are to be treated. B) Subperiosteal ‘‘tunneling’’ dissection.C) Introduction of a piezoelectric microsaw with angled inserts throughthe tunnel approach.D) Performance of interproximal corticotomiesbetween the roots of the targeted teeth. Crown direction serves as anexternal reference; endoscopic control permits in situ vision.

Figure 2.Endoscopic view of the corticotomy. Bleeding confirms the cut hasreached the spongiosa. The arrow shows a dehiscence of the buccalplate of the canine.

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as a result of periodontal compression.2 Conversely,consistent with the initial phase of the RAP, cortico-tomy-facilitated orthodontics seems to entail a pro-cess of localized osteopenia in which the thin layerof bone that overlies the root prominence to be

moved demineralizes and later remineralizes at thecompletion of the orthodontic therapy.7,8 Accordingto this theory, selective bone injury results in an over-whelming activating stimulus for both the catabolicand anabolic responses in the periodontium.13 Thissequential demineralization–remineralization phenom-enon justifies the facilitated tooth movement after cor-ticotomy surgery.7,8 Technical variables, such asamount of decortication, depth of cut, and use of on-lay grafts, may alter the RAP response.11 Extendingthis concept to other types of bone cuts, such as theosteotomies performed in the context of orthognathicsurgery, it is possible that the greater pace and effi-ciency of orthodontic movements observed with a‘‘surgery first’’ approach19 is also attributable to in-creased bone turnover in the alveolar bone adjacentto the osteotomies.20,21

Various types of orthodontic-facilitating corticoto-mies have been proposed. The accelerated osteo-genic orthodontics technique (AOO) described byWilcko et al.7,8,17 implies: 1) a sulcular-releasingincision; 2) full-thickness flap elevation labially andlingually; 3) ‘‘bone activation’’ bymeans of circumfer-ential corticotomy cuts with burs; and 4) bone graft-ing. The procedure is performed under intravenousor oral sedation and takes 3 to 4 hours for a full casein which the upper and lower arches are treated. Al-though quite effective, this technique and subsequentmodifications entail long surgical times and signifi-cant trauma derived from the elevation of large flapsand the extensive nature of the corticotomies. More-over, the performance of bone cuts with burs imply

Figure 3.A) Tunnel approach through two incisions behind the canine to reachthe posterior teeth. B) Corticotomy performance with piezosurgery. C)Wound closure.

Figure 4.Postoperative CBCTevaluation in a case in which the anterior maxillaryteeth were targeted. In this patient, the corticotomy has been extendedto the lingual cortical bone.

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potential damage to the teeth attributable to close rootproximity and impaired bony regeneration as a resultof excessive heat.10

The introduction of ultrasonic microsaws permitsa safe corticotomy around the root with maximumprecision and surgical control.2 Hard- and soft-tissuehealing is rapid and entails minimal morbidity, elimi-nating the risk of osteonecrosis.22 Vercellotti andPodesta2 have applied this technology for their mono-cortical tooth dislocation and ligament distractiontechnique (MTDLD). However, this procedure still re-quires extensive approaches (one full-thickness flap,buccal or palatal, on the side corresponding to the di-rection of movement), generally under intravenoussedation as well. In addition to ensuing patient dis-

comfort, the MTDLD method islinked to long hours of surgery,10

although Vercellotti and Podestadid not report specific surgicaltimes. Conversely, ourminimallyinvasive procedure through thetunnel approach typically lastsan average of only 26 minutes.Hence, local anesthesia is enoughto provide adequate analgesiaandpatient comfort for thisproce-dure.

Another treatment modalityis ‘‘speedy orthodontics,’’ devel-oped by Chung et al.1,23 Thisprocedure is specifically aimedat correcting anterior protrusionwith or without open bite. It usesa corticotomy through a full-thickness flap and an orthopedicforce with intraosseous tempo-rary anchorage. The force ap-plied after the corticotomy isgreater than the typical ortho-dontic force because the aim istomove the circumscribed blockof bone rather than the teeththrough the bone.1,6 In contrastwith our method and AOO andMTDLD techniques, speedy or-thodontics requires the removalof a section of cortical bone fol-lowed by orthopedic tractionagainst the isolated block ofbone and teeth. We only per-formed a ‘‘box osteotomy’’through four interdental corticot-omies in one patient (Fig. 4). Ac-cording to Chung et al.,23 thistechnique produces bony blockmovement as a result of surface

corticotomy, strong orthopedic forces, bone bending,and RAP. In these authors’ protocol,1,23 the maxillarypalatal and buccal corticotomies are performed at dif-ferent surgical times, 2 to 3 weeks apart. Hence, al-though this procedure may be performed under localanesthesia, it entails two surgical appointments withtheir respective postoperative periods of discomfortand a prolonged treatment time.

Recently, alternative procedures have been pro-posed to reduce chairside time and postoperativediscomfort, increase patient acceptance of the pro-cedure, and achieve a stronger periodontium. Theseobjectives were also the motivation for our minimallyinvasive method. Dibart et al.10,18 have popularizedthe concept of ‘‘piezocision,’’ a procedure that entails

Figure 5.Example of one completed case (1-year follow-up). A) The patient underwent bimaxillaryorthognathic surgery, esthetic rhinoplasty, and corticotomy-facilitated orthodontics in the anteriorsegments of the maxilla and mandible. Total orthodontic time lasted 9 months. B) A stableocclusion with an adequate periodontal status and satisfactory facial esthetics are clinically evidentpostoperatively.

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small incisions, minimal piezoelectric osseous cuts tothe buccal cortex only, and bone or soft-tissue graft-ing. As in our protocol, piezocision is performed underlocal anesthesia through a tunnel approach. However,piezocision involves 10 vertical interproximal inci-sions, whereas our procedure uses only one to threebuccal vertical incisions per arch (at the upper or lowermidline and/or behind the upper canine, depending onthe targeted teeth). In this manner, one single mesialincision allows access to the six anterior teeth, andone single distal incision allows access to the premo-lars and molars of one quadrant. This reduced accessis possible due to the angled inserts of the piezoelec-tric saw and the precise endoscopic control over thecorticotomy design and depth. Indeed, the endoscopeprovides illumination and magnification as well asimproved control of root position. The procedure isendoscopically assisted and not endoscopically per-formed, because the endoscope is used to check onthe action of the microsaw once it has been removedfrom the tunnel.

Regardless of the corticotomy-facilitated ortho-dontics technique performed, potential repercussionson the periodontiumare a crucial issue. It is absolutelyimperative that an accurate periodontal diagnosisis established before treatment initiation and thatperiodontal checkups are regularly performed aftersurgery and throughout orthodontic movements. Ifperiodontal disease is diagnosed at baseline evalua-tion, it must be properly treated and stabilized beforethe instauration of any orthodontic treatment.1 Re-search has shown that orthodontic movement ofplaque-infected teeth can interfere with the configura-tion of the connective tissue attachment and give wayto infrabony pocket formation.24 Our method intendsto be as respectful with the periodontium as possibleand thereby avoids sulcular incisions and full-flap el-evation. Moreover, the use of the piezosurgery micro-saw together with endoscopic assistance provides aquick, reliable means to selectively cut the boneand facilitate the preservation of root integrity. Corti-cotomy design and performance are based on directcrown vision (and the corresponding imaginary lon-gitudinal axis of the tooth), together with the tactilesensation of the interdental concavity between theroot prominences. When limitations such as rootproximity, root convexity, or abnormal root angula-tions are present in the posterior segment, the use ofangled inserts of the piezoelectric saw together withthe direct vision provided by the endoscope is anefficient way to maximize root safety. In our opinion,full-flap elevation does not add to the safety or preci-sion of the procedure because tooth roots are stillconcealed by the cortical bone, although it does en-tail increased morbidity for the periodontium. In ourseries, patients showed: 1) good maintenance of in-

terdental papillae, 2) no changes in periodontal PD,3) no significant reduction in crestal bone height, and4) no evidence of root damage at 12 months follow-up. Most patients are still under ongoing orthodontictreatments; a final report will be presented at the ap-propriate time.

CONCLUSIONS

The authors present a simple yet effective techniqueto achieve rapid orthodontic tooth movement. Atunnel approach through one to three buccal verticalincisions per arch is used to minimize soft-tissuedebridement and periodontal risks. Endoscopic assis-tance is useful to design and perform the corticotomiesand to select the sites needing bone augmentation.The preservation of root integrity is further maxi-mized with the use of piezosurgical instruments.Compared to traditional corticotomies, the procedurehas manifest advantages in surgical time, technicalcomplexity, patient morbidity, and periodontiumpreservation.

ACKNOWLEDGMENT

The authors report no conflicts of interest related tothis case series.

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16. Shih MS, Norrdin RW. Regional acceleration of remod-eling during healing of bone defects in beagles ofvarious ages. Bone 1985;6:377-379.

17. Murphy KG, Wilcko MT, Wilcko WM, Ferguson DJ.Periodontal accelerated osteogenic orthodontics: Adescription of the surgical technique. J Oral MaxillofacSurg 2009;67:2160-2166.

18. Dibart S, Surmenian J, Sebaoun JD, Montesani L.Rapid treatment of Class II malocclusion with piezocision:Two case reports. Int J Periodontics Restorative Dent2010;30:487-493.

19. Nagasaka H, Sugawara J, Kawamura H, Nanda R.‘‘Surgery first’’ skeletal Class III correction using theSkeletal Anchorage System. J Clin Orthod 2009;43:97-105.

20. Hernandez-Alfaro F, Guijarro-Martınez R, Molina-CoralA, Badıa-Escriche C. ‘‘Surgery first’’ in bimaxillaryorthognathic surgery. J Oral Maxillofac Surg 2011;69:e201-e207.

21. Villegas C, Uribe F, Sugawara J, Nanda R. Expeditedcorrection of significant dentofacial asymmetry usinga ‘‘surgery first’’ approach. J Clin Orthod 2010;44:97-103, quiz 105.

22. Vercellotti T, Nevins ML, Kim DM, et al. Osseousresponse following resective therapy with piezosurgery.Int J Periodontics Restorative Dent 2005;25:543-549.

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24. Ericsson I, Thilander B, Lindhe J, Okamoto H. Theeffect of orthodontic tilting movements on the peri-odontal tissues of infected and non-infected dentitionsin dogs. J Clin Periodontol 1977;4:278-293.

Correspondence: Dr. Federico Hernandez-Alfaro, Instituteof Maxillofacial Surgery, Teknon Medical Center, Vilana,12, D-185, 08022 Barcelona, Spain. E-mail: director@institutomaxilofacial.com.

Submitted April 17, 2011; accepted for publication August19, 2011.

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