Effect of piezopuncture obone remodeling in dogs

Young-Seok Kim,a Su-Jung Kim,b Hyun-Joo Yoon,a PeterSeoul, Korea, and Los Angeles, Calif

Introduction: The aim of the study was to elucidate whethpiezopuncture, would be a logical modication for acceleraMethods: Ten beagle dogs were divided into 2 groups. Trin the control group. In the experimental group, a piezotomegingiva around the moving tooth. Measurements were ma

s wethe popunreatalsoon tunc(Am

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facilitated orthodontics1; therefore, development of

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activation that we called piezopuncture. In this proce-

resultant electrical eld; this creates alternating and per-

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All authors have completed and submitted the ICMJE Form for Disclosure of Po-tential Conicts of Interest and none were reported.

0889-5406/$36.00Copyright 2013 by the American Association of Orthodontists.

ORIGINAL ARTICLEdure, an ultrasonic tool, a piezotome, is used to createmultiple cortical punctures through the overlying gingiva.The concept of ultrasonic osteotomy is based on the so-called reciprocal piezo effect: voltage is applied to a polar-ized piezo ceramic to deform a piezoelectric crystal in the

Supported by Korea Ministry of Education, Science and Technology (number2009-0092562).Reprint requests to: Young-Guk Park, Department of Orthodontics, Kyung HeeUniversity, School of Dentistry, 1 Hoegi-Dong, Seoul 130-701, Korea; e-mail,ygpark@khu.ac.kr.Submitted, February 2012; revised and accepted, January 2013.piezoelectric cortical incisions with selective tunneling,which allows additional tissue grafting.

To overcome the insufciencies of these earlier proce-dures, we conceived a novel procedure for cortical

at Los Angeles, Calif.dAssistant professor, Section of Orthodontics, School of Dentistry, University ofCalifornia at Los Angeles, Calif.eProfessor and chair, Department of Orthodontics, School of Dentistry, KyungHee University, Seoul, Korea.http:/plications has been a topic of special interest. Full-kness ap elevation with extensive decortications,ding various modications of corticotomies, areoubtedly effective in increasing cellular activities re-

to tooth movement.1-3 The mechanism oflerated tooth movement by a regional acceleratoryomenon depends mainly on transient osteopenia

than cortical removal is required.Corticision (patent 0843344, class 10; Kyung H

University, Seoul, Korea) was introduced as a miniminvasive alternative for cortical activation.5,6 A cortincision made by malleting a reinforced scalpelseparate the interproximal cortices transmucosally wfound to induce the regional acceleratory phenomeneffect for faster tooth movement in beagle dexperiments.5 To mitigate the patients' fear and discofort from repeated malleting, Dibart et al7,8 suggespiezocision, a process that uses an ultrasonic tooproduce the incisions. This procedure combi

raduate student, School of Dentistry, Kyung Hee University, Seoul, Korea.tant professor, Department of Orthodontics, School of Dentistry, Kyungniversity, Seoul, Korea.ent, Section of Orthodontics, School of Dentistry, University of Californiaregional acceleratory phenomenon that is less prone to a simple procedure just for cortical activation ratherapposition rates from the histomorphometric analysecumulative tooth movement distance was greater infold in the maxilla and 2.45-fold in the mandible. Piezat all observation times, and the acceleration was gsecond week for the mandible. Anabolic activity wasand 2.35-fold in the mandible. Conclusions: Basedand the mandible, the results of a clinical trial of piezopa therapeutic benet for reducing treatment duration.

Various surgical interventions on the periodontaltissues have been developed to accelerate ortho-dontic tooth movement. The degree of inten-tional surgical damage needed to evoke a long-lasting/dx.doi.org/10.1016/j.ajodo.2013.01.022n tooth movement and

Joohak Lee,c Won Moon,d and Young-Guk Parke

er a newly developed, minimally invasive procedure,ting tooth movement in the maxilla and the mandible.aditional orthodontic tooth movement was performedwas used to make cortical punctures penetrating thede in weeks 1 through 6. Tooth movement and bonere evaluated by independent t tests. Results: Theiezopuncture group than in the control group: 3.26-cture signicantly accelerated the tooth movementsest during the rst 2 weeks for the maxilla and theincreased by piezopuncture: 2.55-fold in the maxillahe different effects of piezopuncture on the maxillature with optimized protocols might give orthodontistsJ Orthod Dentofacial Orthop 2013;144:23-31)

by an accelerated demineralization-remineralizationprocess, providing a more pliable environment,4 whichis distinct from bony block movement in corticotomy-pendicular expansion and contraction of the material.

23

unctuzopuingivg noen th

24 Kim et alBecause of its accurate and selective capability of cuttingmineralized tissues without damaging adjacent soft tis-sues and nerves, ultrasonic osteotomes were rst used inperiapical oral surgery, including implantology9 and peri-odontology.10 These transmucosal manipulations of alve-olar bone have minimized morbidity and achieved similarresults tomore aggressive procedures, including extensiveap elevation for rapid tooth movement.11,12

The aim of our study was to elucidate whether piezo-puncture would elicit the regional acceleratory phenom-enon and accelerate tooth movement without causingharmful tissue responses. The acceleration rates of toothmovement and bone remodeling were investigated andcompared between the maxilla and the mandible.

MATERIAL AND METHODS

Ten male beagles (age, 18-24 months; weight, 9-12

Fig 1. Orthodontic force application: A, piezopsecond premolar movement in each jaw; B, pieof the second premolar, penetrating overlying gwere found around the puncture sites, showintitanium closed-coil springs were activated betweage teeth. xxx, Specimen collection sites.kg) were housed in separate cages supplied with a self-washing system, air conditioning, and lighting accord-ing to the guidelines of the Institutional Animal Careand Use Committee, Kyung-Hee University Medical Cen-ter. The dogs were randomly divided into 2 groups: con-trol (n 5 4) and piezopuncture (n 5 6). These groupswere further divided into 3 subgroups based on theduration of force application: group I, 14 days (control,n5 1; piezopuncture, n5 2); group II, 28 days (control,n 5 1; piezopuncture, n 5 2); and group III, 42 days(control, n5 2; piezopuncture, n5 2). Each animal pro-vided 4 specimens (1 each from the right and left sides ofboth jaws), and the maxillary and mandibular specimens(n 5 20 for each jaw) were randomly divided into 2groups. Animals in the control group received orthodon-tic force alone, and the animals in the piezopuncturegroup received orthodontic force with piezopuncture.The animals were killed at 2, 4, and 6 weeks after theinterventions.

July 2013 Vol 144 Issue 1 AmericanThe target teeth in both arches were the second pre-molars; however, the anchorage teeth in each arch wereselected differently because of anatomic limitation. Inthe maxillary arch, the second premolars were protractedagainst the canines as the anchorage, whereas the sec-ond premolars were retracted against the third premolarsin the mandibular arch. Orthodontic buttons (Ormco,Orange, Calif) connected by a lever arm were bondedon the labial surfaces of all experimental teeth withSuper-Bond C&B resin (Sun Medical, Shiga, Japan). Anickel-titanium closed-coil spring (Tomy International,Tokyo, Japan) was activated and ligated between the le-ver arms of the target teeth and the anchorage teeth. Forreinforcing anchorages, resin bridges were constructedon the adjacent teeth. The orthodontic force by the ap-pliance was 100 g at the beginning of the experiment.Tooth movement was allowed for 6 weeks. Force magni-

re procedure: arrows indicate the direction ofncture was performed on the mesiobuccal sidea into the cortical bone; white ring-like lesionslethal damage on the soft tissues; C, nickel-e lever arms of the target teeth and the anchor-tude was measured using a force gauge (Haag-Streit,Koeniz, Switzerland) once a week with reactivation ofthe appliance to maintain a continuous force (Fig 1, A).

For piezopuncture, a piezosurgical instrument witha sharp curved tip (Endo2 insert, ProUltra; DentsplyMaillefer, Ballaigues, Switzerland) was used to performthe cortical punctures penetrating the gingiva. Thedepth of cortical injury was 3 mm, by holding the tipperpendicular to the gingiva for 5 seconds undersaline-solution irrigation. The setting selected for eachpuncture was in accordance with the manufacturer'srecommendation. Piezopunctures were performed onthe mesiobuccal, distobuccal, mesiolingual, and disto-lingual sides of the second premolars (Fig 1, B). Sixteenpunctures were made on 1 target tooth. Gentamicin(7.5 mg/kg) was injected postoperatively for 3 days.Tooth brushing and daily hexamedine (Bukwang, Seoul,South Korea) irrigation were repeated during thepostoperative care.

Journal of Orthodontics and Dentofacial Orthopedics

each

move94516 0.022716 0.80054z

66586 0.115236 0.20041z

\0.00

cture

Kim et al 25Table I. Accumulative distances of tooth movements in

Jaw Group Beagle site Second premolarMaxilla Control (A) A1-RT 0.7

A1-LT 0.7A2-RT 0.6A2-LT 0.7Mean 0.72

Piezopuncture (B) B1-RT 2.6B1-LT 3.3B2-RT 1.5B2-LT 1.7Mean 2.31P value 0.0

Mandible Control (A) A1-RT 0.5A1-LT 0.7A2-RT 0.3A2-LT 0.3Mean 0.51

Piezopuncture (B) B1-RT 1.7B1-LT 1.3B2-RT 1.1B2-LT 1.1Mean 1.33P value 0.0

Independent t test was performed (mean 6 SD, *P\0.05; y\0.01; z

anchor teeth were the third premolar and the rst molar.A1, First control beagle; A2, second control beagle; B1, rst piezopunTooth movement was measured by a digital caliper(Mitutoyo, Kawasaki, Japan) on the stone models oncea week. In the maxillary arch, the distance from the me-sial cervix of the third premolar to the mesial cervix of themoved second premolar was measured over time. In ad-dition, the distance of canine retraction as an anchoragetooth was measured from the mesial cervix of the thirdpremolar to consider the rate of tooth movement asthe relative ratio. In the mandibular arch, the distancefrom the mesial cervix of the canine to the mesial cervixof the moved second premolar was measured, and theprotracted distance of the anchored third premolar wasalso measured from the same reference. The relativevalues of the distance of the moved teeth divided bythe distances of the anchorage teeth were compared be-tween the groups.

Histologic analysis was performed on the decalciedspecimens at 2, 4, and 6 weeks. Tissue blocks includingthe second premolar with surrounding alveolar bone andthe injury site were decalcied with 10% EDTA-2Na (pH7.4) at 48C for 30 days. The specimens were resected at3 to 4 mm below the alveolar crest with thicknesses of 6mm. The sections were stained with hematoxylin andeosin for descriptive histology.

Quantitative histomorphometric analysis was doneon the nondecalcied specimens of the dogs in the 6-week groups. One experimental animal and 1 control

American Journal of Orthodontics and Dentofacial Orthopedgroup at 6 weeks after orthodontic force application

ment, A (mm) Anchor tooth movement, B (mm) Ratio (A/B)0.98 0.811.12 0.661.15 0.571.10 0.65

6 1.09 6 0.07 0.67 6 0.101.01 2.591.07 3.101.28 1.231.07 1.60

2 1.11 6 0.12 2.13 6 0.860.27102 0.00215y

0.38 1.470.59 1.290.28 1.250.35 1.09

9 0.40 6 0.13 1.28 6 0.160.31 5.520.56 2.410.58 1.930.39 2.90

8 0.46 6 0.13 3.19 6 1.600.55436 0.04373*

1). In the maxilla, the anchor tooth was canine; in the mandible, the

beagle; B2, second piezopuncture beagle; RT, right side; LT, left side.animal were randomly selected. They had been intra-muscularly injected with 3 uorochoromes as follows:oxytetracycline hydrochloride (yellow orange, 30 mg/kg; Fluka Chemie AG, Buchs, Switzerland) at 24 hoursbefore intervention and at 6 weeks after intervention;calcein (green, 10 mg/kg; Fluka Chemie AG) at 2 weeksafter intervention; and alizarin red (red, 30 mg/kg; FlukaChemie AG) at 4 weeks after intervention. Specimenswere taken from 8 sampling sites in each jaw. Thesespecimens were longitudinally sectioned parallel to thedirection of orthodontic traction and examined underan ultraviolet uorescence microscope (BH-2; Olympus,Tokyo, Japan) with an ultraviolet lter (l 5 515 nm).Microphotographs of all specimens were recorded usinga digital CCD camera (PS30C ImageBase; Kappa Op-tronics, Gleichen, Germany). The outlines of labeledbones were traced from the photographs, and the dis-tances between the labeled lines were measured with im-age analysis software (ImageBase Metreo 2.5; KappaOptronics).

Statistical analysis

Descriptive statistics were represented as means andstandard deviations for all parameters in each group.The normality of the data was assessed with theKolmogorov-Smirnov test. Statistical homogeneity waschecked using the Levene test. Independent t tests

ics July 2013 Vol 144 Issue 1

26 Kim et alwere used to evaluate the intergroup differences of themean tooth movement distances on the models andthe mean accumulated new bone deposition measuredby histomorphometric analysis. Values of P \0.05were considered statistically signicant.

RESULTS

The mean cumulative distances of tooth movementfor 6 weeks as well as the ratios of target tooth move-ment to anchorage loss were signicantly increased inthe piezopuncture groups as opposed to the controlgroups in both the maxilla and the mandible (TableI). The distance of the maxillary second premolar move-ment in the piezopuncture group (2.31 6 0.82 mm)was 3.26-fold greater than that in the control group(0.72 6 0.06 mm). The distance of the mandibular sec-ond premolar movement in the piezopuncture group(1.33 6 0.28 mm) was 2.45-fold greater than that inthe control group (0.51 6 0.19 mm). There was no sig-nicant difference in the amount of anchorage toothmovement between the piezopuncture group (maxilla,1.11 6 0.12 mm; mandible, 0.46 6 0.13 mm) andthe control group (maxilla, 1.09 6 0.07 mm; mandible,0.40 6 0.13 mm). The relative ratios of maxillary toothmovement were 2.15 6 0.98 in the piezopuncture

Fig 2. Accumulated tooth movement distances and m

July 2013 Vol 144 Issue 1 Americangroup and 0.66 6 0.02 in the control group. The ratiosof mandibular tooth movement were 3.30 6 1.03 inthe piezopuncture group and 1.35 6 0.75 in thecontrol group.

With respect to movement rate, the rst 2 weeks inthe maxilla and the second week in the mandible hadthe greatest movement (Fig 2). The weekly velocity oftooth movement in the piezopuncture group was largerthan that in the control group at all observation times.The increasing pattern of the accumulated distances oftooth movement in the piezopuncture group showedno remarkable stagnation indicating the lag phase.

Descriptive histologic ndings on the compressionsides of moving teeth are shown in Figure 3. At week2, the periodontal ligament was compressed and locallydegenerated into hyalinization in the control group,where no apparent resorptive ndings on the alveolarsurfaces were observed (Fig 3, A). In the piezopuncturegroup, osteoclasts with the resorption lacunae alongthe bone surfaces were seen near hyalinized areas ofthe periodontal ligament (Fig 3, B). At week 4, indirectresorption followed by the removal of the hyalinizedperiodontal ligament was found in the control group(Fig 3, C), whereas direct resorption by active bone-resorbing cells continued in the piezopuncture group

ovement rates in the maxilla and the mandible.

Journal of Orthodontics and Dentofacial Orthopedics

Kim et al 27(Fig 3, D). At week 6, the number and the activity ofbone-resorbing cells were decreased, showing sparse re-sorption areas on the bone surface with focal hyaliniza-tion in the control group (Fig 3, E), whereas the ndingsof direct bony resorption with the cellular periodontalligament were as before in the piezopuncture group(Fig 3, F). There were no recognizable differences ofthe time-dependent histologic responses between themaxilla and the mandible.

Fig 3. Microphotographs of periodontal tissues on thetrol group at 2 weeks;B, piezopuncture group at 2 weegroup at 4 weeks; E, control group at 6 weeks; F, piezoresorption lacunae with bone-resorbing cells along tgroups, hyalinization was found at 2 and 6 weeks, anOn the contrary, in the piezopuncture groups, directtimes without remarkable hyalinization. B, Alveolar botion. Original magnication: 200 times.

American Journal of Orthodontics and Dentofacial OrthopedFluorescent microscopic ndings of anabolic boneremodeling on the tension sides of the moving teeth(Fig 4) showed correspondence with rate of tooth move-ment. The accumulated distance of newly mineralizedbone apposition during 6 weeks was signicantly greaterin the piezopuncture group than in the control group(Table II). In the maxilla, the mean apposition lengthof the piezopuncture group was 2.55-fold greater thanthat of the control group. The distance between the rst

pressure sides of the second premolars:A, con-ks;C, control group at 4 weeks;D, piezopuncturepuncture group at 6 weeks. The arrows indicatehe compressed alveolar surface. In the controld indirect resorption was observed at 4 weeks.bone resorption was evident at all observationne; P, periodontal ligament; R, root; H, hyaliniza-

ics July 2013 Vol 144 Issue 1

els o

28 Kim et alFig 4. Fluorescent microphotographs of bone labyellow line (oxytetracycline at 24 hours before interven-tion) and the red line (alizarin red at 4 weeks) was strik-ingly increased in the maxillary piezopuncture group. Inthe mandible, the mean apposition length in the piezo-puncture group was 2.35-fold greater than that in thecontrol group. The distance between the green line (cal-cein at 2 weeks) and the second yellow line (oxytetracy-cline at 6 weeks) was remarkably increased in themandibular piezopuncture group.

DISCUSSION

This beagle study shows that a newly developed sup-plemental procedure, piezopuncture, accelerated therate of orthodontic tooth movement and the remodelingprocess of alveolar bone without causing collateral dam-age. Earlier and greater effects of piezopuncture wereobserved in the maxilla than in the mandible.

Piezopuncture was developed to increase patientcompliance by minimizing discomfort during and after

maxillary bone apposition in the control group; B, mamandibular apposition in the control group; D, mandibcumulated distances between the bone-labeled linegroups than in the control groups in both jaws. Earlierserved in the maxilla compared with the mandible. Or

Table II. Mean accumulated distances of new bone appositiosion side

Jaw Group Weeks 0-2 (mm/wk)Maxilla Control 44.44 6 30.27

Piezopuncture 122.89 6 23.12Mandible Control 35.18 6 13.02

Piezopuncture 98.56 6 24.58

Distances were measured from the nondecalcied specimens in the 6-weekcontrol animal were randomly selected (means 6 SD were calculated from s

July 2013 Vol 144 Issue 1 Americann the tension sides of the second premolars: A,surgery, and to simplify the procedure for orthodontists.Piezopuncture uses a piezotome, which acts as a light ul-trasonic scaler. Unlike the previous surgical interven-tions, piezopuncture eliminates the use bonemalleting, which can be frightening to the patient, andthe soft-tissue incision and suture.1-5 In contrast tocorticision,5 such an approach for minimizing tissuedamage, and the intensity and duration of the regionalacceleratory phenomenon, might not be sufcient tofunction throughout the entire orthodontic treatment.13

However, this problem could be eliminated by repeatedapplications at regular intervals; this would be more fa-vorable for the patients' convenience than more aggres-sive methods.

The action mechanism of piezopuncture is based onthe biologic concept of cortical activation rather thancortical removal.14 Most previous corticotomy-facilitated orthodontic treatments were designed to re-sect the cortical barrier, depending on the mechanical

xillary apposition in the piezopuncture group; C,ular apposition in the piezopuncture group. Ac-s are signicantly longer in the piezopunctureand larger responses to piezopuncture were ob-iginal magnication: 100 times.

n in both arches indicated by uorescence on the ten-

Weeks 2-4 (mm /wk) Weeks 4-6 (mm/wk)56.09 6 8.52 78.35 6 7.31

158.09 6 38.09 116.00 6 17.2545.17 6 15.08 25.55 6 7.34

148.07 6 39.68 123.18 6 6.60

groups; 8 sampling sites in each jaw of 1 experimental animal and 1ampling sites of each jaw).

Journal of Orthodontics and Dentofacial Orthopedics

d bos werthe m

Kim et al 29concept of the cortex. The use of a minimal interventionto achieve an objective suggests a keen knowledge of theregional acceleratory phenomenon physiology and a re-spect for a discrete surgical technique. Garg15 empha-sized that the regional acceleratory phenomenon isinitiated mainly by trauma to the cortical bone. The cor-tex is regarded as a necessary matrix for rapid toothmovement, not an obstacle.3,15 Only cortical activationcan increase osteoclastic activity around theperiodontal ligament, facilitating bone turnovertoward an osteoporotic state with less tissue resistanceto tooth movement. Teixeira et al16 suggested that os-teoperforation placed far from the tooth could acceler-

Fig 5. Mean apposition rates of newly mineralizePeak velocity periods in the piezopuncture groupweeks 4 to 6 was higher in the mandible than inate the rate of tooth movement, reected by anincreased level of inammatory cytokine expression, fol-lowed by extensive osteoporotic changes. In addition tothis conceptual change, understanding the 2-sided char-acteristic of inammation has enabled the continuousadvancement of supplemental surgical techniques withminimal and conservative interventions.

Piezosurgical incisions have been reported to besafe and effective in osseous surgeries, such as prepros-thetic surgery, alveolar crest expansion, and sinusgrafting.17-21 Because of its micrometric and selectivecut, the piezosurgical knife is said to aid safe andprecise osteotomies without osteonecrotic damage.Vercellotti and Podesta21 used a piezosurgical techniquefor periodontally accelerated orthodontic tooth move-ment. Dibart et al7,8 introduced piezocision asa modied method of corticision for rapid orthodontictooth movement. Piezocision is different frompiezopuncture in that it requires soft-tissue incisionswith a blade and routine tissue grafting with the blindedtunneling technique. Grafting mimics the accelerated

American Journal of Orthodontics and Dentofacial Orthopedosteogenic orthodontic treatments in the studies ofWilko et al2 and Murphy et al,3 which need to be dis-cussed separately from cortical activation. Additionally,the previous evaluations on piezoelectricity for acceler-ating tooth movement, based on clinical reports, havenot yet provided biologic evidence.

This beagle experiment elucidated that the corticalactivation by piezopuncture accelerated tooth move-ment signicantly at each observation time. Since ortho-dontic tooth movement aims to restore the balance byremodeling the periodontal ligament, it is reasonableto assess the timing of bone apposition in conjunctionwith tooth movement.22 To explore the anabolic

ne on the tension sides of the second premolars.e at 2 to 4 weeks in both jaws, and the velocity inaxilla.mechanism in response to tooth movement with corticalactivation, it was prudent to analyze the uorochrome-labeled lines histomorphometrically. The rates of toothmovement in the control group showed no remarkableincrease until 5 weeks after intervention, accompaniedby increased rates of new bone apposition in 4 to 6weeks. On the other hand, the piezopuncture groupshowed earlier acceleration of tooth movement in therst 2 weeks after intervention, followed by signicantlyincreased rates of new bone apposition during laterweeks. This acceleration of tooth movement could alsobe supported by different catabolic activities betweenthe 2 groups, even though it was not based on quantita-tive analysis. Extensive hyalinization with little bone re-sorptive activity, indicating the biologic lag phase oftooth movement, was remarkable at 2 and 6 weeks inthe control group, whereas direct bone resorption con-tinued at all experimental periods in the piezopuncturegroup without evidence of a lag phase.23-25 Themechanism of bypassing the lag phase indicates lessproduction and faster elimination of hyalinization, and

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be effective to facilitate tooth movement, and the effect

30 Kim et alit is mentioned in the study of Baloul et al22 about selec-tive alveolar decortication; this corresponds to our re-sults of a less invasive cortical puncture.

The acceleration effect of piezopuncture was faster inthe maxilla than in the mandible. Deguchi et al26 re-ported that orthodontic tooth movement progressed 2weeks faster in the maxilla than in the mandible, andthat higher rates of tooth movement in the maxillawere found at 4 through 6 weeks. In our study,piezopuncture-assisted tooth movement advanced 1week faster in the maxilla than in the mandible. The pie-zopuncture group demonstrated a peak in tooth move-ment at weeks 1 and 2 in the maxilla and weeks 2 and3 in the mandible, and peaks in bone apposition ratewere at weeks 2 through 4 in the maxilla and weeks 2through 6 in the mandible (Fig 5). Although the absoluteamount of bonemass is stable during conventional toothmovement, even with highly dynamic metabolic activity,a transient osteoporotic state occurs during surgically fa-cilitated tooth movement.2,22 Because of the differencesof bone density and metabolism between the jaws, themaxillary teeth should be regarded as more sensitive tothe regional acceleratory phenomenon by corticalactivation than are the mandibular teeth. Nevertheless,the mean ratio of target tooth movement to theanchorage tooth movement was higher in the mandiblethan in the maxilla; this contradicts the result ofcomparing the distances of the target teeth themselves.This discrepancy can be explained because the meanamount of anchorage tooth movement was greater inthe maxilla than in the mandible. This might imply thatthe accelerating effect of piezopuncture was moreextensive to the anchorage part in the maxilla but wasrather localized on the target tooth area in themandible. It should be also considered that our beaglemodel included mesial movement of the maxillarysecond premolars and distal movement of themandibular second premolars, depending on thedifferent anchorage values.

Tooth movement with or without surgical interven-tion is a combined process of osteoclastic and osteoblas-tic activities in response to external stimulation.27,28 It isnot clear yet whether tooth movement by surgicalstimulation follows the same mechanism asconventional tooth movement, or whether a differentbiologic pathway is involved. Nonetheless, a superiorcondition of surgically assisted tooth movement is thatthe tooth goes through the osteoporotic alveolar boneof a less tissue-resistant environment. We had presup-posed that the biologic mechanisms underlying rapidtooth movement by cortical puncture would be

similar to the previously reported demineralization-remineralization process of decortication.29 Although

July 2013 Vol 144 Issue 1 Americanwas greater and faster in the maxilla than in the mandi-ble. Simultaneously, the regional acceleratory phenome-non effect was more extensive in the maxilla; hence,reinforcement of the anchorage part is needed in clinicalapplications.

With further studies on the development of pro-longed acceleration of tooth movement over time, thelimitations of minimally invasive surgical proceduresshould be complemented and modied toward clinicalefciency. Based on the different acceleratory effectsof piezopuncture on the maxilla and the mandible,a clinical trial of repeated piezopuncture with optimizedapplication intervals and force adjustments would giveorthodontists a great therapeutic benet in the contextof reducing treatment durations.

CONCLUSIONS

This study introduced a novel periorthodontic tech-nique, piezopuncture, which enables rapid tooth move-ment without damaging side effects. This techniqueinvolves puncturing of the cortical bone with a piezosur-gical regimen. Piezopuncture was found to evoke rapidtooth movement by accelerating the rate of alveolarbone remodeling. The acceleration of orthodontic toothmovement associated with piezopuncture was expli-cated by increased bone turnover through the regionalacceleratory phenomenon.

Although further studies on the optimal power rangeof a piezosurgical device to induce a regional accelera-tory phenomenon with orthodontic tooth movementare suggested for secure clinical applications, piezo-puncture might have a great therapeutic benet in thecontext of reducing treatment duration and also peri-odontal regeneration in its best extent. This develop-ment is expected to bring orthodontics closer to thegoal of efciency in tooth movement, without causingpatient discomfort or damage to the teeth and their sup-porting tissues.

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Journal of Orthodontics and Dentofacial Orthopedics

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Effect of piezopuncture on tooth movement and bone remodeling in dogsMaterial and methodsStatistical analysis

ResultsDiscussionConclusionsReferences