English translation from:Orthod Fr 2011;82:311–319© EDP Sciences, SFODF, 2011DOI: 10.1051/orthodfr/2011142

Disponible en ligne sur :www.orthodfr.org

Original article

Accelerated orthodontic treatments with Piezocision:a mini–invasive alternative to alveolar corticotomies

Jean-David M. SEBAOUN1,2 *, Jérôme SURMENIAN1,3, Serge DIBART1

1 Department of Periodontology, Boston University, 100 East Newton Street, Boston MA 02118, États-Unis2 115 cours Jean Jaurès, 38000 Grenoble, France3 23 rue Alphonse Karr, 06000 Nice, France

(Received 9 March 2011, accepted 24 March 2011)

ABSTRACT – An increasing number of adult patients are seeking orthodontic treatmentand a short treatment time has become a recurring request. To meet their expectations, anumber of surgical techniques have been developed to accelerate orthodontic toothmovement. However, these have been found to be quite invasive. We are introducing herea new, minimally invasive flapless procedure, combining micro incisions, piezoelectricincisions and selective tunneling that allows for hard- or soft-tissue grafting. Combined witha proper treatment planning and a good understanding of the biological events involved,this novel technique can locally manipulate alveolar bone metabolism in order to obtainrapid and stable orthodontic results. Piezocision allows for rapid correction of severemalocclusions without the drawbacks of traumatic conventional corticotomy procedures.

KEYWORDS:Corticotomy /Rapid orthodontics

1. Introduction

1.1. Alveolar cortocotomies and rapid orthodontic treatments

An increasing number of adult patients are seek-ing orthodontic treatment and a short treatment timehas become a recurring request.

Significant acceleration in orthodontic toothmovement has been extensively reported followingalveolar corticotomies since the end of the 19th century.

In 1959, Köle [9] described a surgical procedurecombining vertical inter-proximal cortical incisionswith a subapical horizontal osteotomy cut from thebuccal to the palatal plate. The author explains thatrapid tooth movements observed following the sur-gery are caused by what he believed to be bony “blockmovements” more or less independent of each other.Subsequently, many authors publish variants of thetechnique where the subapical osteotomy was re-moved and where only superficial corticotomy inci-sions were realized. However, all explained that rapid

* Corresponding author : jdsebaoun@gmail.com

Article publié pa

tooth movements were allowed by the “bony block”movements concept [1, 4, 6, 20].

In 2001, Wilcko [25] introduced a techniquecombining alveolar corticotomies and bone graftingto prevent the risk of dehiscence and fenestrationwhile increasing the scope of orthodontic correc-tions. In this conventional approach, cortical inci-sions circumscribing the roots are made on both thebuccal and palatal side following full thickness muco-periosteal flaps (Fig. 1). The bone graft is then placedfacing the teeth to be moved and the flaps are thenrepositioned and sutured at the papilla. The authors[18] further speculated that the rapid orthodonticmovements clinically observed in patients whounderwent selective decortication might be due to ademineralization–remineralization process ratherthan “bony block” movement.

1.2. Biological rationals

In 1981, the orthopedist Frost [5] observed thata surgical wounding of the bone induces an increasedbone turnover and a decreased bone density in the im-mediate surrounding of the surgical site (RAP, RegionalAcceleratory Phenomenon). This post-surgical state of

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osteopenia is described as a transient condition, givingway to a complete remission of bone density graduallyas physiological healing progresses [7, 10].

Furthermore, many studies underlined a relation-ship between the rate of tooth movement and the rateof alveolar bone turnover. Verna [23], pharmacologi-cally induced high or low rates of bone turnover anddemonstrated that an increased turnover is associatedwith a displacement significantly faster. These resultsare consistent with those reported by Midgett [13] andAshcraft [2].

Recent animal studies have confirmed the Wilckohypothesis that clinically observed rapid tooth move-ment following corticotomy may be due to Frost’sRegional Acceleratory Phenomenon and not to theconcept of movements known as “bony blocks”.

At the histological level, we reported in the rat areversible increase in bone turnover following alveo-lar corticotomy [19]. Three weeks after surgery, oste-oblastic and osteocalcic activities were increased by afactor of three and returned to steady state values ateleven weeks postoperative. We also noted that theseeffects were limited to immediate environment of thesurgical site.

Other authors have assessed the quality andquantity of orthodontic movements following corti-cotomy in the animal model. Ren [17] observed fastertooth movement associated with a significant increasein the rate of bone turnover at the surgical site aftercorticotomy in the Beagle dog. Mostafa [14] reportedtwice faster tooth movements after corticotomy in thedog and also attributed this effect to the increasedbone remodeling observed histologically and to Re-gional Acceleratory Phenomenon (RAP).

These findings are consistent with the work ofLino [12] for whom accelerated movements are asso-ciated with rapid response in the bone marrow and

Figure 1

Conventional alveolar corticotomy. Cortical incisions are madeusing a bone bur following muco-periosteal buccal and palatal/lingual flaps.

with a lesser hyalinization. Similar observations havebeen reported in rats after corticision (increasedresorption and apposition) and less hyalinization [8].

Moreover, by comparing orthodontic movementafter corticotomies to those obtained after osteoto-mies, Wang [24] and Lee [11] confirmed the RegionalAcceleratory Phenomenon (RAP) as the events re-sponsible for rapid movements.

Displacements by distraction osteogenesis are ob-served in cases of osteotomies and not following sim-ple corticotomies thus refuting the concept of “bonyblock” movements.

1.3. Alternatives to conventional corticotomies

Although effective, corticotomy techniques de-scribed above present significant postoperative dis-comfort. The aggressive nature of these particularmethods related to the elevation of muco-periostealflaps and to the length of the surgery raised reluctanceamong both patients and dental community.

In addition, all the authors mentioned aboveperformed the cortical incisions using a bone bur thatcould potentially damage the roots of neighboringteeth (in case of severe crowding in the anterior man-dible).

In 2006, Park [15] introduced the corticisiontechnique and removed the need for flaps elevationby conducting their incisions directly through thegingiva using a blade and a surgical hammer. Whilesignificantly reducing the duration of the surgery, thistechnique does not provide the benefits of bone graftof the Wilcko technique. In addition, the highlyaggressive use of the hammer and chisels in themaxilla adds a risk of benign paroxysmal positionalvertigo [16].

In 2007, Vercellotti [22] reported a reduction ofthe orthodontic treatment time by 60 to 70% aftercorticotomy performed by means of a piezosurgicalmicro-saw. Due to their small size and their precision,piezoelectric cutting inserts realize precise osteoto-mies without the risk of osteonecrosis [21]. Theauthor removed the lingual flap by performing onlyvestibular incisions but the elevation of a flap prior tothe corticotomy was maintained thus only relativelyreducing surgical time and postoperative discomfort.

To overcome the disadvantages of other corticot-omy techniques, we are introducing [3], an innovative,minimally invasive, flapless procedure combining pie-zosurgical cortical micro-incisions with selective tun-neling that allows for bone or soft-tissue grafting.

Sebaoun J.D.M., Surmenian J., Dibart S. Accelerated orthodontic treatments with Piezocision 313

2. Piezocizion: minimally invasive technique of alveolar corticotomy

2.1. Initial periodontal examination and management

Piezocision technique addressing primarilyadult patients, a complete periodontal assessmentincluding periodontal probing and full-mouth X-Rays must be conducted.

Systematic scaling (and root planing if indicated)must be performed prior to the surgery in order toremove any inflammation that could jeopardize a suc-cessfull healing. Any detected osseous lesion shouldbe treated before considering a Piezocision proce-dure.

Moreover, because of the lack of mucoperiostealflap elevation in the piezocision technique, we highlyrecommend the use of preoperative three-dimen-sional imaging (Cone Beam Computerized Tomogra-phy) to locate areas of root proximity as well as themental foramen (Fig. 2). These images also allow thepractitioner to assess the quantity and location ofareas where a bone graft would be indicated.

Figure 2

3D Imaging (Cone beam computed tomography) for surgicalplanning. Preoperative randering allows to localize anatomicalrisks and to assess the thickness of the cortical bone and theareas of fenestrations where a bone graft would be indicated.

a

b

2.2. Surgery (Fig. 3)

The surgery is performed under local anesthesia,a week following the placement of the orthodonticappliance. Gingival vertical incisions are madeinterproximaly below the interdental papilla using anumber 15 blade and kept as much as possible in theattached gingiva. These incisions do not require to beextended (micro-incisions) but they must cross theperiosteum allowing the blade to come into contactwith the alveolar bone. Ultrasonic instrumentation(BS1 insert Piezotome™, Satelec Acteon GroupMérignac, France) is then used to perform corticot-omy cuts through the gingival micro-incisions and toa depth of 3 mm. Note that no suture is requiredexcept in areas where a bone graft is placed.

At the areas requiring bone augmentation, a tun-nel is performed by means of an elevator insertedbetween the gingival incisions to form sufficient spacefor receiving the graft. The allograft (Puros, Zimmer)is then placed and the incision sutured (absorbablesutures 5-0).

Typically the graft is performed in case of severecrowding in mandibular anterior region. While onlythree gingival incisions (between the centrals and dis-tal to the laterals) are necessary for tunneling, we notethat the cortical incisions are made between eachtooth.

When extractions are indicated, they can bemade during the intervention. As RAP obtained bycorticotomy is limited to the immediate proximity ofthe cuts [19], two cortical incisions should be per-formed facing the extraction site to facilitate rapid clo-sure of the space.

Note that all of the incisions (and the graft whenrequired) are made only buccally. The lingual andpalatal approaches of conventional corticotomiesdisappear.

At the end of the procedure, the patient is placedon antibiotics, nonsteroidal anti-inflammatory drugsand mouthwashes containing chlorhexidine.

Surgical sites should be avoided while brushingduring the first postoperative week to allow harmoni-ous gingival healing.

2.3. Orthodontic Follow-up

After surgery, patients are monitored every twoweeks for their orthodontic adjustments. The majororthodontic movements are obtained within fourmonths following the surgery emphasizing the tran-sient nature of RAP. From our experience, it appears

314 Orthod Fr 2011;82:311–319

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areaI

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h

that the majority of cases are dealt within a range of5 to 9 months depending on the severity of the initialmalocclusion.

From a periodontal standpoint, patients are mon-itored at one week postoperatively and then everymonth to ensure proper plaque control and reinforcenecessary hygiene techniques (Fig. 4).

3. Clinical applications

3.1. Indications

Careful selection of cases is a decisive factor onthe clinical success of this technique. Patients shouldpresent a stable periodontium without periodontaldisease, not be affected with a local or general bone

Figu

Surgery. (a) Micro-incisions are made through the attached gingivSatelec) to a depth of 3 mm. (d) Three incisions are made in the aa tunnel that can accommodate the bone graft. (f) The interproximrial. (h) The incisions are closed tightly with simple points (5.0). (i)racter of the surgery.

a b

d

g

disease or be subjected to a treatment such as immu-nosuppressive or bi-phosphonate.

Motivation and cooperation of the patient areessential in Piezocision as in corticotomy patients. Infact, the teransient nature of RAP obtained after thesurgery requires a frequency of appointments higherthan conventional technique to achieve the majormovements in the first months of treatment.

From an orthodontic standpoint, the ideal candi-date for this procedure presents a class I or a mild classII associated with moderate to severe crowding.Severe deepbites are also corrected in a timely mannerfollowing Piezocision. In extraction cases, especiallyin full Class II patients, the teeth will be extracted dur-ing the surgery and two to three cortical incisions willthen be performed facing the alveolus (Fig. 5).

e 3

. (b and c) Bone is decorticated using the BS-1 insert (Piezotome,a needing bone augmentation. (e) An elevator is used to createl areas are decorticated. (g) Insertion of the bone grafting mate-mmediate post-surgical view. Notice the minimally invasive cha-

c

f

i

Sebaoun J.D.M., Surmenian J., Dibart S. Accelerated orthodontic treatments with Piezocision 315

c d e

a

b

f

Figure 4

Periodontal follow-up of patient in figure 3. (a and b) Pre-treatment panoramic radiograph and full mouth xrays to evaluate bone leveland root proximity for surgical planning. (c, d and e) Healing assessment one week post-piezocision. (f) Post-treatment panoramicradiograph for bone level control. Note that the wisdom teeth will be extracted later on.

ba c

Figure 5

Correction of Class II by rapid canine retraction after Piezocision. (a) Two to three cortical incisions are made facing the socket ofthe extracted tooth and surrounding the teeth to be moved. (b) Before canine retraction phase. (c) Four weeks following placement

of the retraction coils (300 g Sentalloy GAC®).

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ios

Moreover, the procedure we are describing can beperformed in a segmental manner (pre-prostheticintrusion, treatment of a single arch...) or be incorpo-rated within a comprehensive ortho-surgical treatmentplan allowing for rapid decompensation of the archesprior to moving skeletal bases by orthognathic surgery.

Finally, the observed acceleration of orthodonticmovements being based on a localized modificationof bone physiology, Piezocision may be associatedwith various orthodontic treatment techniques (buc-cal braces, lingual braces and Invisalign®…).

3.2. Advantages

The technique described here presents similarclinical outcomes to those obtained following con-ventional corticotomy with the advantages of beingshorter to perform, minimally invasive and much lesstraumatic for the patient.

Clinically we observe a decrease in the durationof treatment equivalent to that obtained by corticot-omy (Fig. 6). It appears that the majority of even se-vere malocclusions are resolved within 5 to 9 months.The active treatment times are therefore three timesshorter than those usually observed after conventionaltreatment of similar malocclusion.

When combined with bone grafting, Piezocisionallows for an increase scope of treatment includingallowing the correction of severe crowding withoutextraction.

From a technical standpoint, 45 min to 1 h isusually sufficient for a complete surgery on both themaxilla and mandibule with bone grafting againstthree to four hours for traditional techniques.

Furthermore, if conventional methods could beassociated with some periodontal complications(mild bone loss and partial loss of interdental papilla),it appears that not raising a flap in the minimally inva-sive technique avoids those risks.

Finally we note that the postoperative discomfortafter Piezocision is much lighter and allows a returnto normal activities soon after surgery. In our clinicalexperience, we do not report major edema or

Figu

Patient presenting a Class I malocclusion associated with severemonths and three weeks with maxillary and mandibular Piezocisneling in the inter-canine region of the mandibule. Occlusal viewmonths and three weeks after Piezocision. Note that the major m

hematoma of the face as described after invasive cor-ticotomies [6]. Postoperative pain is usually minimaland well tolerated by patients.

3.3. Disadvantages and limitations of the technique

Because of the lack of muco-periosteal flap eleva-tion, cortical incisions may present a risk of root dam-age particularly in areas of close root proximity. A riskalso exists at the mental foramen. A panoramic radi-ograph and retroalveolar images of those areas areessential to the preparation of the surgery. The contri-bution of three-dimensional imaging compensate forthe lack of direct vision of the bony structures (Fig. 2).

Extra care is also required as to the location ofgingival incisions. It is very important to keep at least2 mm from the gingival margin to avoid the formationof gingival cleft.

In addition, for patients presenting ethnic gingi-val pigmentation, soft tissue incisions can create acosmetic concern. In fact, each incision may leave atrace without proper repigmentation, thereby causingcosmetic damages in patients with excessive gingivaldisplay. Those patients must be warned against poten-tial risk of post-operative scars.

4. Conclusion

Piezocision is an innovative, minimally invasive,flapless procedure combining piezosurgical corticalincisions with selective tunneling that allows for boneor soft-tissue grafting. This innovative techniqueallows for the orthodontic correction of severe maloc-clusions in less than a semester without the downsideof the extensive and traumatic surgical approaches. Itoffers a shorter surgical time, minimal postoperativediscomfort, a high tolerance for patients as well as animproved periodontium.

The Piezocision reveals itself as a powerful tool inthe arsenal of multidisciplinary dental team for ouradult patients.

e 6

crowding (8 mm) and 50% overbite. Treatment completed in sixn from first molar to first molar coupled with a bone graft by tun-: (a) before treatment, (b) four months after Piezocision, (c) six

ovements are obtained in the first months following the surgery.

Sebaoun J.D.M., Surmenian J., Dibart S. Accelerated orthodontic treatments with Piezocision 317

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e f g

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