Lasers and dento-facial orthopedics: an interview with

Lasers and dento-facialorthopedics: an interviewwith Samir Nammour

Philippe AMAT, Jacques BERREBI, Franck HERVE

Samir NAMMOUR is a professor at the Dental School of the University of Liege.A specialist in the use of lasers in dentistry, he served as president of the WorldFederation for Laser Dentistry (WFLD) until 1908 and is currently the director ofthe European Masters Degree in Oral Laser Applications program.

Philippe AMAT, Jacques BERREBI, Franck

HERVE. Professor Sam Nammour, you are

the director of the European Masters

Degree in Oral Laser Applications pro-

gram. Because of your contributions to it,

all its participants have awarded you

with a bronze star prize. This honor

presented within the framework of the

European Life-Long Education and Train-

ing program, reflects the recognition

throughout the continent of 3rd cycle

diplomas for dentists. Can you tell us

about the modalities and objectives of

this program?

Samir NAMMOUR. The three universities ofNice, in France, of Aix-la-Chapelle inGermany, and Liege in Belgium, have,independently, been offering courses inthe use of lasers in dentistry since the year

2000. Then one day we began to wonderwhy we should all be working, isolated, inour private academic fief-doms? Whycouldn’t we pool our resources and presenta single, more comprehensive, unifiedcourse? We presented this border breachingconcept to the European Community,asking that the three universities beauthorized to offer a common diploma tobe called the European Masters Degree inOral Laser Applications, (EMDOLA). Aftertwo years of joint teaching experience, wewere delighted to learn that the EuropeanCommunity was ready to grant final accep-tance of our project. We hope to continueoffering the highest quality instructionthat would unite the best potentials devel-oped in each of the three participatinginstitutions.

Address for correspondence:

J. BERREBI,20, rue Val de Bouille,72240 Conlie.

DOI: 10.1051/odfen/2009405 J Dentofacial Anom Orthod 2009;12:145-155� RODF / EDP Sciences

145

Article available at http://www.jdao-journal.org or http://dx.doi.org/10.1051/odfen/2009405

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http://dx.doi.org/10.1051/odfen/2009405

P.A., J.B., F.H. Do you plan to

introduce the EMDOLA project in

other European countries?

S.N. That’s a good question. InSeptember 2008, three new universi-ties, Parma and Rome in Italy,and Barcelona in Spain, joined ourEMDOLA group, which now em-braces six schools. We have had toreject the application of two additionaluniversities but we hope they will haveimproved their standards sufficientlyfor us to accept them next year.

P.A., J.B., F.H. What are the

possibilities of inter-university stu-

dent exchange studies within your

EMDOLA group?

S.N. Our goal is to make suchexchanges readily available. We haveorganized instruction in modules pre-sented at staggered dates so thatstudents will be able to attend awidely diverse range of courses indifferent universities.

In addition we have coordinated ourefforts to that teachers will be givingcomparable courses in all the partici-pating schools, with courses givenalternatively at each university.

P.A., J.B., F.H. Before we go into

greater detail about the indications

for the use of each of them, can you

outline for us the characteristics of

the different types of lasers, CO2,

Erbium Yag, and others that are

utilized in dentistry?

S.N. The therapeutic applicationof the Carbon Dioxide laser, CO2,

laser is derived from its capabilityof instantaneously releasing an in-tense burst of heat that can fuse harddental tissues. Its capability of in-

stantly evaporating soft tissue andexecuting extremely precise, totallybloodless, cuts and excisions makesit a useful surgical tool as well.

As for the laser Erbium Yag, it isprimarily characterized by its power ofsending a light ray that, in contact withhard tissue, provokes a micro-explo-sion, which, when repeated, allowsdentists to progressively remove hardtissue.

P.A., J.B., F.H. What are the

principal applications of lasers in

dentistry?

S.N. The CO2. laser has become theinstrument of choice in oral surgery.Its indications, advantages, and limitshave been clearly understood formany years.

The Erbium-Yag (Er: Yag) laser isprimarily employed in conservativedentistry thanks to its efficacy inremoving hard tissue. Although it isless efficient and slower in cuttingthrough soft tissue, it can still beemployed surgically, espe cially inreshaping gingival tissues.

The fiber lasers, like the Neodyme-Yag (Nd: Yag), and the Neodyme-Yap(Nd: Yap), the only laser made inFrance, as well as the diodes ofvarying lengths, have much morelimited applications. They are em-ployed in endodontics because of theircapability of providing light in areas ofdifficult access through an uncoveredtip. Acting in the interior of rootchambers they warm disinfecting li-quids such as sodium hypochlorite,which enhances their effect, while atthe same time removing infectedtissue. This action is accompanied byvibrations that participate in eliminat-

PHILIPPE AMAT, JACQUES BERREBI, FRANCK HERVE

146 Amat P, Berrebi J, Herve F. Lasers and dento-facial orthopedics: an interview with Samir Nammour

ing the smear layer as well as indiffusing the disinfections productsfurther into the canal complex oftubules and secondary canals.

Periodontists can employ fiber la-sers to cleanse supra or infra-osseousperiodontal pockets. In the supra-oss-eous pockets, the beneficial action ofthe lasers cans be seen on threelevels.

– First, they restore health to thegingiva by reducing acute inflamma-tion. This effect, which is immediateand quite spectacular, becomes evi-dent as the gingiva changes in color;

– Second, lasers provide a deconta-mination action, whose effectiven-ess depends on the wave lengthemployed;

– And, finally, lasers set off a bio-stimulation effect that promotes cel-lular regeneration and improvement ingingival health.

But it should be emphasized thatuse of lasers in no way relievesclinicians from performing tried andtested basic treatment like prophylac-tic removal of tartar.

P.A., J.B., F.H. You have written

several articles8,9 about using the

Argon laser to improve dental en-

amel’s capacity to retain fluoride

coating. Can you outline for us the

clinical applications of this techni-

que as well as the current status of

your research?

S.N. Dental caries, quite properlyconsidered to be a scourge, has a highworldwide prevalence. We hope to beable to contribute to the prevention ofthis malady by a fluoride enrichmenttechnique, whose modest cost, weanticipate, will make it readily availableto great numbers of people, no matter

how limited resources or how dis-tressed local conditions may be.

After application of a fluoride gel onteeth, our technique consists of irra-diating the dental surface with an Argonlaser. After 30 seconds of exposure tothis beam, a sufficiently large amountof fluoride will be incorporated imme-diately and permanently into the enam-el. We are at present proposing thisprotocol to our patients.

P.A., J.B., F.H. Can you tell us

whether you are now at the pre-

liminary trial stage or have you

already begun clinical applications

of your method?

S.N. After having obtained excellentresults with numerous clinical studies,I think I can safely say we have nowreached the stage of applying our technique clinically.

P.A., J.B., F.H. You are one of the

co-authors of a recent clinical study

published in Photomedicine and

Laser Surgery 2 that was devoted

to the applications of the laser

Nd:YAG and 810 nm and 980 nm

diodes in soft tissue orthodontie

surgery. What are the advantages

of this new operative technique

compared to conventional ones?

Have you observed a decrease in

post-operative pain or in the time

required for healing?

S.N. The use of lasers for softtissue surgery provides no benefitswith respect to post-operative pain orlength of the healing process. In fact,the sutures that conclude conven-tional surgery assure a more rapid firstintention healing. But the advantage ofthe laser technique lies preciselythere: the wound requires no sutures,but the second intention healing timeis also longer.

A LASERS AND DENTOFACIAL ORTHOPEDICS: AN INTERVIEW WITH SAMIR NAMMOUR

J Dentofacial Anom Orthod 2009;12:145-155 147

The article that your question callsup illustrates the two principal advan-tages of laser fibers; the operativeprocedure is completely bloodlessbecause the laser seals off capillariesand it can be performed in areas forwhich access would otherwise beextremely difficult or impossible. Aspecial case where elimination ofbleeding is extremely helpful is ex-posure of impacted teeth, which,because of the dry field, are immedi-ately available for successful bondingof attachments, allowing orthodonticmovement to begin without delay.

P.A., J.B., F.H. You are saying,

then, that fiber lasers are the in-

strument of choice, particularly in

orthodontics, because they can be

used in areas that would not be

accessible to other lasers, like CO2?

S.N. Exactly. The rays of light thatemerge from a CO2 cannot be carriedalong by a fiber. For those areas whereaccess is difficult, it is, therefore,sometimes necessary to use anotherwave length (lasers Nd:YAG, Nd:YAP orDiodes), even if they are otherwise lessappropriate for that procedure. Theyare less efficient on soft tissue becausetheir water content does not allowthem to be readily absorbable.

P.A., J.B., F.H. Can you explain for

our readers why a laser rather than

a conventional surgical procedure

should be selected for an operation

on a deeply inserted frenum?

S.N. Lasers give dentists a finecutting edge that allows them to passsafely between the teeth to vaporizethe ensemble of fibrous soft tissueright up to their insertion into bone.The surgical site is completely clearedof blood and the sterilizing power ofthe laser greatly reduces the risk of

post-operative infection (fig. 1 a to cand fig. 2).

Another advantage is that pain isless than in the traditional way ofvigorously curetting the fibrous inser-tions in the inter-maxillary suture. Thiscurettage, which, of necessity, mustbe pursued well into the bone causesintense post-operative pain that mustbe relieved with analgesics over aperiod of several days. But patientsrequire pain medication when lasersare used only on the day of thesurgery and, perhaps for a half-dayafterwards.

P.A., J.B., F.H. Do these consid-

erations apply to the resection of a

lingual frenum?

S.N. Absolutely. For this type ofprocedure the CO2 laser providespractitioners with great cutting preci-sion, excellent hemostasis, and asignificant reduction in post-operativepain (fig. 3 a to c, and 4 a to e).

P.A., J.B., F.H. What benefits

do you think lasers bring to the

surgical-orthodontic uncovering

of an impacted tooth, a canine, for

example?

S.N. In these cases, their indicationis superb and truly original. If, forexample laser execution of a frenect-omy presents undeniable advantages,frenectomies can be accomplishedperfectly adequately by conventionalsurgery.

But lasers uncovering impactedteeth (fig. 5 a to f) work so muchbetter than conventional surgery that itwould be unconscionable not to allowour patients to benefit from thembecause, as I have said, they alloworthodontic bonding and traction tobegin immediately thanks to thehemostasis of the operative field.



Figure 1 aMaxillary median labial frenum witha low insertion (documents Fornaini,et al.2).

Figure 1 bUse of a Diode to vaporize all fibroustissue right up to its insertion inbone. Note the perfect hemostasisobtained in their surgical site.

Figure 1 cView of the site 7 days after thesurgical procedure. The presence ofa fibrous pellicle indicates that heal-ing is proceeding satisfactorily.

Figure 2For another patient the surgeon has used a longwave CO2 laser in order to make a very fine incisionbetween the teeth without injuring them (from therecords of J. Berrebi).

Figure 3 aExtremely tight, or ankylosed lingualfrenum (from the records of J.Berrebi).

Figure 3 bConcentrated pulsations from a CO2

laser have freed the frenum from itstwo attachments, to the tongue andto the lingual incisal mucosa. In thisview taken immediately after thelaser procedure, the perfect hemos-tasis in this highly vascularized re-gion can clearly be seen.

Figure 3 cThe tongue demonstrates the greatextent of its newly achieved mobi-lity.



P.A., J.B., F.H. Another indication

for the use of lasers in orthodontics

is in the treatment of gingival

hyperplasia, which we see princi-

pally in patients who are unable to

effectively control build up of dental

plaque in their mouths. Is the pre-

sence of metal brackets on pa-

tients’ teeth a contra-indication for

removing excessive soft tissue?

S.N. Dentists can, perhaps, obviatethis obstacle by using lasers, like CO2,

whose wave lengths metal does notabsorb but reflects as though themetal were a mirror. This type ofwave length, located in the infra-redarea, does not heat metal at all,meaning they pose no threat to theintegrity of the bonds of attachments.

Thanks to the CO2 laser dentistscan recontour gingival margins withprecision and with no risk of a post-operative gingival recession occurring,thus allowing patients to return to the

Figure 4 aA Short lingual frenum that deforms the point of thetongue giving it the contour of a heart shaped playingcard (from the records if S. Nammour).

Figure 4 bA Close-up view of that same thick, short, and fibrouslingual frenum.

Figure 4 cA view of the operating site after its

isolation.

Figure 4 dA view of the site taken immediatelyafter the operation. The slight carbo-nization of the site, always super-ficial with a CO2 laser, is normal forthis stage.

Figure 4 eThe result after 60 days.



desired impeccable oral hygiene sohelpful in orthodontic treatment.

P.A., J.B., F.H. What role, in your

opinion, can lasers play in the

treatment of apthous ulcers. These

lesions are particularly disabling

when patients are wearing fixed

appliances.

S.N. Lasers diminish laser diminishthe severity of the inflammatory reac-tion and thus immediately reducepatients’ discomfort after the lesionhas been irradiated. And then they

participate in a speeding-up of theulceration’s healing.

As for simple ulcerations andbruises caused by irritation from theappliance, lasers are quite effective inaccelerating their healing. Of course,for that result to be permanent, thepractitioner should be certain toremove the causative mechanicalirritant.

P.A., J.B., F.H. Let’s get back, if you

will, to re-contouring the gingiva

with a CO2 laser. Would you proceed

Figure 5 aSurgical uncovering with a laser ofan impacted maxillary central incisor(from the records of Fornaini, et al 2).

Figure 5 bIn the same visit, thanks to the laserimposed hemostasis of the operat-ing field, an attachment was effec-tively bonded to the exposed labialsurface of the tooth.

Figure 5 cOrthodontic movement of the im-pacted tooth was begun by tying itto the arch wire with an elasticligature.

Figure 5 dTermination of initial stage of ortho-dontic movement of the impactedtooth.

Figure 5 eThe hook type attachment wasreplaced with a bracket to allowfor final positioning of the impactedtooth.

Figure 5 fAfter movement with a light wire theimpacted tooth has assumed its posi-tion in the arch.



by stretching or lengthening the

gingiva or by thinning it out?

S.N. I would begin with removingexcess tissue until I obtained the levelI wanted (the eventual limit of thecervical gingiva), by making the tissuetaut in order to incise it: this means "acut with a focalized bundle". Then thepractitioner completes the procedurewith a CO2 weak in power, two orthree Watts, to thin out the gingiva in asweeping movement, because if thetissue is left too thick it will heal withan unaesthetic thick contour. The lasercan serve as well in establishing thethickness of the healed gingiva,which, cut to a proper thinness, willretain the desired proportions.

It is important to mention that thepractitioner must preserve the integ-rity of the dental enamel with the aidof a polished metallic instrument asthe gingivoplasty is being carried out.

P.A., J.B., F.H. Many recent arti-

cles have discussed the possibility

of reducing the pain that accompa-

nies orthodontic treatment with

low level laser therapy (LLLT)11, or

by using a CO23 laser. Can you tell

us more about this concept?

S.N. The LLLT laser produces noimmediately visible effect on irra-diated tissue. However, it releases aquantity of energy whose absorptioninto tissue will have an anti-inflamma-tory action. In this way it might reduceorthodontic pain that is inflammatoryin origin.

P.A., J.B., F.H. What about the

use of a CO2 laser?

S.N. Currently physiotherapists areusing the anti-inflammatory action ofCO2lasers to treat lesions and painthat result from inflammation. Toobtain this effect, they direct a low

level defocalizing CO2 laser beam atthe selected site. Dentists can use thesame procedure by aiming the defo-calizing low level, 0.2 Watts at most,CO2 beam from a distance of ±3 cm atthe treatment site. The irradiationmust be delivered with a circularmovement around the chosen arearapidly, ±1 cm / sec, for a period of 1to 3 minutes. The practitioner can stopirradiating the area as soon as achange in color, from a deep red tolighter shade, is perceived. The sametreatment can be repeated every otherday, three times a week, if necessary.

P.A., J.B., F.H. The results of a

preliminary study, published last

year by Youssef, et al.12, seem to

suggest that the action of a soft

laser (LLLT) can help teeth to move

faster in response to orthodontic

force. What do you think about

that?

S.N. Lasers act on tissues byimproving the activity of the cells theyreach. Thus, it is plausible to imagine,as the osteoclasts and osteoblastsperform more effectively, that thephenomenon of apposition-resorptionmight accelerate and speed up therate of tooth movement.

P.A., J.B., F.H. In the treatment of

some malocclusions, especially of

adults whose periodontium has, not

infrequently, begun to deteriorate,

orthodontists have to deal with the

problem of denudation of root sur-

faces and the pain that accompanies

it. Can you tell us something about

the use of the Nd :Yag laser in a

pulsating mode for desensitizing

exposed cementum?

S.N. Our team has developed aprotocol which stipulates choice ofappropriate wave lengths adapted to



fuse the affected dental surface andthus close up entry to dentinal tubules.This superficial tubular blockage, whichprevents any flow of liquids, confersdesensitization that lasts for at leasttwelve months, which happens to bethe exact length of time our study hasbeen active. So, of course, the reliefcould be much longer.

P.A., J.B., F.H. So the Nd: Yag is

the laser of choice for this type of

procedure?

S.N. Precisely. Its photothermalaction fuses the dentinal surface byheating the tissues, which takes careof the problem of exposed root sur-face. But the effect is not just super-ficial and the pulp could be at risk fromdeep penetration of heat because theliquid present in the dentine does notabsorb Nd :YAG laser beams to anyuseful extent. Fortunately we havelearned how to limit the diffusion ofthe laser heat without weakening itseffect on the exposed root surface. Todo that we cover the root with a blackgraphite based gel that absorbs theunwanted Nd: YAG beams withoutinterfering with surface action.

P.A., J.B., F.H. In view of the

published studies that indicate ad-

hesion of bonding agents to enamel

surfaces etched with the Er:YAG

laser is inferior7 to or, at best,

equivalent5 to surfaces etched with

acid, do you think that orthodon-

tists ought to use lasers for this

purpose?

S.N. Yes, these studies do showthat when only the Erbium -YAG laseris used to etch enamel, the results arenot optimal. But when it is combinedwith traditional phosphoric acid

etching of enamel, there is a signifi-cant increase in bond strength 5.

However, our team at the Universityof Liege is now developing an entirelynew protocol in which we conditionthe enamel by irradiation with the Er:YAG laser in a pre-determined fashion.We follow this conditioning with acidetching. The bonding carried out onthis surface is superior, by 50%, tothat obtained by traditional etchingwith no preparatory laser conditioning.We have submitted this study to thejournal "Lasers in Medical Science" forfuture publication.

P.A., J.B., F.H. Orthodontists can

select ceramic brackets as a more

esthetically alternative to metallic

attachments in their treatment of

malocclusions. Unfortunately their

weak resistance to fracture and the

strength of their adhesion to enam-

el, which makes them hard to

remove at the termination of ther-

apy, are serious drawbacks. One

suggestion to facilitate debonding

is to heat them10. But poor control

of the heat level during this process

might put the dental pulp at risk.

Do you think CO2 laser can be used

safely and effectively in the removal

of ceramic brackets?

S.N. The CO2 laser can, in fact, beused for this indication. The orthodon-tist aims the beam at the bracket,which will absorb the heat and trans-fer it to the bonding agent causing it tosoften and lose its grip on the bracket.You are quite right to bring up the riskto the dental pulp but this can beavoided if the practitioner takes painsto protect the enamel surface with aninstrument, for example that would



absorb excess heat and channel itaway from the tooth surface.

P.A., J.B., F.H. Are you confirming

that ceramic brackets will effec-

tively absorb the CO2 laser beam?

S.N. Certainly.P.A., J.B., F.H. White spots left on

the enamel surface at the close of

treatment can compromise the

esthetic result of orthodontic treat-

ment. Knosel, et al.4. have sug-

gested that orthodontists can

attenuate the unaesthetic impact

of white spots by external whiten-

ing of the dentition. Do you think

orthodontists could use the KTP

laser as an effective solution in

treating patients who have this

problem?

S.N. Definitely. Dentists can whitenteeth very effectively by working witha KTP laser and a gel precisely placedand well adapted. I am proud to beable to recommend our own gel,which is made in Belgium, Smartble-ach�*. It contains rhodamine, whosered coloration absorbs the energyemitted by the KTP and thus preventsover-heating of the dental pulp.

P.A., J.B., F.H. RJ. Lanzafame has

brought up the question of the cost

to dentists of buying lasers6. Do

you think the high price of this

Investment is justified?

S.N. Dentists can justify an invest-ment of this type if they choose alaser truly adapted to their clinicalneeds. A CO2 laser, for example,would be appropriate for orthodontistsbecause it works well for tasks theycan be called upon to perform such asre-contouring gingival tissue, frenec-

tomies, exposing impacted teeth, anddebonding ceramic brackets. But, ofcourse, if you select a type of a laserthat does not respond to your practiceneeds, you are sure to suffer frombuyer’s remorse.

P.A., J.B., F.H. Do you think the

price of lasers will come down in

the near future?

S.N. Certainly. Their price will de-crease as the demand for themincreases. In fact, when supplyhouses become aware of how manylasers are being sold, more and moreof them will want participate in theirdistribution. This increase in competi-tion combined with the progressiveamortization of their cost of develop-ment will inevitably lead to a drop intheir price.

P.A., J.B., F.H. Dentistry is the last

medical specialty to utilize lasers,

which are already widely employed

in oncology, dermatology, ophthal-

mology, plastic surgery, and gastro-

enterology. What are the future

prospects for their use the various

branches of dentistry?

S.N. Lasers make it possible fordentists to perform certain procedureswithout great difficulty that were for-merly impossible or exquisitely de-manding. That is why I am convincedthat in time we shall all be workingwith lasers that have been carefullychosen to fit our precise needs in ourdaily practice of dentistry.

P.A., J.B., F.H. Thank you very

much, Professor Nammour, for the

Information you have provided and

for the courtesy you have shown to

the readers of our Revue.

We are grateful to Fornaini, et al.2,the authors of the article in which thephotos and case presentations illus-

*Smartbleach International / Mutsaardstraat 47 /9550. Herzele Belgie.



trating treatment of impacted teethand performance of frenectomies ap-peared.

The photos in figures 2 and 3 aredocuments that J. Berrebi provided.

Readers will find in the first article inthe bibliography an aid to making areasoned choice in the purchase of alaser that will best fit their needs1.

REFERENCES

1. Berrebi J, Bien choisir son laser un acte raisonne. Rev Orthop Dento Faciale2009;43:377-83.

2. Fornaini C, Rocca JP, Bertrand MF, Merigo E, Nammour S, Vescovi P. Nd:YAG andDiode Laser in the surgical management of soft tissues related to orthodontictreatment. Photomed Laser Surg 2007;25:381-92.

3. Fujiyama K, Deguchi T, Murakami T, Fujii A, Kushima K, Takano-Yamamoto T.Clinicaleffect of CO2 laser in reducing pain in orthodontics.Angle Orthod. 2008;78:299-303.

4. Knosel.M, Attin R, Becker K, Attin T. External bleaching effect on the color andluminosity of inactive white-spot lesions after fixed orthodontic appliances. AngleOrthod 2007;77:646-52.

5. Lee BS, Hsieh TT, Lee YL, Lan WH, Hsu YJ, Wen PH, Lin CP.Bond strengths oforthodontic bracket after acid-etched, Er:YAG laser-irradiated and combined treatmenton enamel surface.Angle Orthod 2003;73:565-70.

6. Lanzafame RJ. "Business". Photomed Laser Surg. 2007;25:371-2.7. Martinez-Insua A, Dominguez LDS, Rivera FG, Santana-Penin UA. Differences in

bonding to acid- etched or Er:YAG-laser-treated enamel and dentin surfaces. J ProsthetDent 2000;84:280-8.

8. Nammour S, Demortier G, Florio P, Delhaye Y, Pireaux JJ, Morciaux Y, Powell L.Increase of enamel fluoride retention by low fluence argon laser in vivo. Lasers SurgMed. 2003;33:260-3.

9. Nammour S, Rocca JP, Pireaux JJ, Powell GL, Morciaux Y, Demortier G. Increase ofenamel fluoride retention by low fluence argon laser beam: a 6-month follow-up studyin vivo. Lasers Surg Med 2005 Mar;36:220-4.

10. Rickabaugh JL, Marangoni RD, McCaffrey KK. Ceramic bracket debonding with thecarbon dioxide laser. Am J Orthod Dentofacial Orthop. 1996;110:388-93.

11. Turhani D, Scheriau M, Kapral D, Benesch T, Jonke E, Bantleon HP. Pain relief bysingle low-level laser irradiation in orthodontic patients undergoing fixed appliancetherapy. Am J Orthod Dentofacial Orthop 2006;130:371-7.

12. Youssef M, Ashkar S, Hamade E, Gutknecht N, Lampert F, Mir M. The effect of low-level laser therapy during orthodontic movement: a preliminary study. Lasers Med Sci2008;23:27-33.



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Lasers and dento-facial orthopedics: an interview with