Pesqui Odontol Bras 2002;16(4):308-312 Morphologic analysis, by means of scanning electron microscopy, of the effect of Er:YAG laser on root surfaces submitted to scaling and root planing Análise morfológica, através de microscopia eletrônica de varredura, da ação do laser de Er:YAG em superfícies radiculares submetidas à raspagem e aplainamento radicular Le tí cia He le na The o do ro* Val dir Gou ve ia Gar cia** Pa trí cia Hay pek*** De ni se Ma ria Ze zell**** Carlos de Paula Eduardo***** ABSTRACT: The pur po se of this study was to morp ho lo gi cally eva lu a te, by me ans of scan ning elec tron mi cros copy, the ef fects of Er:YAG la ser on the tre at ment of root sur fa ces sub mit ted to sca ling and root pla ning with con ven ti o nal pe ri o - don tal ins tru ments. Eigh te en root sur fa ces (n = 18), which had been pre vi ously sca led and pla ned, were as sig ned to 3 groups (n = 6). The con trol Group (G1) re ce i ved no furt her tre at ment; Group 2 (G2) was ir ra di a ted with Er:YAG la ser (2.94 µm), with 47 mJ/10 Hz, in a fo cu sed mode with air/wa ter spray du ring 15 s and with 0.57 J/cm2 of flu ency per pul se; Group 3 (G 3) was ir ra di a ted with Er:YAG la ser (2.94 µm), with 83 mJ/10 Hz, in a fo cu sed mode with air/wa ter spray du ring 15 s and with 1.03 J/cm2 of flu ency per pul se. We con clu ded that the pa ra me ters adop ted for Group 3 re - mo ved the sme ar la yer from the root sur fa ce, ex po sing the den ti nal tu bu les. Although no fis su res, cracks or car bo ni - zed are as were ob ser ved, an ir re gu lar sur fa ce was pro du ced by Er:YAG la ser ir ra di a ti on. Thus, the bi o com pa ti bi lity of the ir ra di a ted root sur fa ce, wit hin the pe ri o don tal he a ling pro cess, must be as ses sed. DESCRIPTORS: La sers; Den tal sca ling; Pe ri o dontics; Sme ar la yer. RESUMO: O objetivo do presente estudo foi analisar morfologicamente, através de microscopia eletrônica de var - redura, os efeitos do la ser de Er:YAG no tratamento de superfícies radiculares submetidas à raspagem e aplainamento radicular com instrumentos manuais. Foram utilizados 18 espécimes (n = 18) de superfícies radiculares que após ser submetidos à raspagem e aplainamento radicular foram divididos em 3 grupos (n = 6). O grupo controle (G1) não sofreu nenhum tratamento; Grupo 2 (G2) foi irradiado com la ser de Er:YAG (2,94 µm) 47 mJ/10 Hz, focalizado,com refrigeração à água du rante 15 s e fluência de pulso de 0,57 J/cm2; Grupo 3 (G3) foi irradiado com la ser de Er:YAG (2,94 µm), 83 mJ/10 Hz, focalizado, com refrigeração à agua du rante 15 s e fluência de pulso de 1,03 J/cm2. Através da análise dos resultados podemos concluir que o la ser de Er:YAG nos parâmetros utilizados no G3 promove a remoção de “smear layer” da superfície radicular e exposição dos túbulos dentinários, porém o la ser promove aspecto ir reg u lar na superfície, apesar de não demonstrar crateras, fendas, fraturas e carbonização, necessitando de estudos que demonstrem a biocompatibilidade desta superfície no processo de reparo periodontal. DESCRITORES: La sers; Raspagem dentária; Periodontia; Camada de esfregaço. INTRODUCTION Me chan i cal root ther apy aims at re mov ing the etiologic agents re spon si ble for periodontal dis - eases caused by in flam ma tory pro cesses. In the last few years, sev eral treat ment al ter na tives have been pre sented to com pen sate the in her ent lim i ta - tions to me chan i cal root ther apy in the periodontal treat ment. Both in vitro6,8,9,10,19,20,24,28,30 and in vivo18,26 stud ies have em pha sized the con di tion ing of root sur faces by means of dif fer ent meth ods as a coadjutant step to the scal ing and root plan ning pro ce dure. It aims at re duc ing the num ber of mi - cro or gan isms on the root sur face in or der to en able 308 Dentística *Mas ter in La sers in Den tistry, Ener ge tics and Nu cle ar Re se arch Insti tu te, PhD Stu dent in Pe ri o don tics; **Cha ir Pro fes sor, De - part ment of Pe ri o don tics – Scho ol of Den tistry of Ara ça tu ba, São Pa u lo Sta te Uni ver sity. ***Mas ter in Res to ra ti ve Den tistry, Scho ol of Den tistry; ****Asso ci a te Re se ar cher, Ener ge tics and Nu cle ar Re se arch Insti tu te; *****Cha ir Pro fes sor, De part ment of Res to ra ti ve Den tistry, Scho ol of Den tistry – Uni ver sity of São Pa u lo. the re gen er a tion of the struc tures dam aged by the periodontal dis ease. The re duc tion of bac te ria on the root sur face is not ef fec tively ac com plished with the uti li za tion of the chem i cal agents de scribed in the lit er a ture, which are ef fec tive in re mov ing the smear layer. Clin i cal stud ies have not dem on strated sig nif i cant ef fects re gard ing the uti li za tion of these agents in the periodontal heal ing process11,12,13. Some au thors have dem on strated the ef fec - tive ness of Er:YAG la ser in re mov ing cal cu lus from the root sur face with out caus ing ther mal damage4,5,15,16,21,23,29. How ever, it is not as ef fec tive as other instruments5. De spite these facts, there are few pa pers on the uti li za tion of Er:YAG la ser as a coadjutant in root me chan i cal ther apy. Ac cord ing to these facts and con sid er ing the lack of stud ies on the ef fects of Er:YAG la ser ir ra di - a tion on root sur faces sub mit ted to scal ing and root plan ing, the aim of the pres ent study is to eval u ate such ef fects by means of scan ning elec - tron mi cros copy, uti liz ing Er:YAG la ser with two en ergy pa ram e ters. MATERIAL AND METHODS Nine roots of sound young hu man pre mol ars, with out periodontal dis ease, hypoplastic de fects or res to ra tions, had been uti lized in this study. All teeth had been ex tracted for orth odon tic rea sons. Pre pa ra ti on of test specimens Af ter ex trac tion, the teeth were cleansed from blood and other de bris and kept in sa line so lu tion at 37ºC for a max i mum pe riod of six months, in or - der to main tain hydration. With a high-speed bur, par al lel grooves were confected on the mesial and dis tal sur faces of teeth: one at the enamel-ce ment junc tion and the other 5 mm away, in api cal di rec - tion, in or der to delimitate the cer vi cal third of the roots. Af ter the groves were confected, a small amount of ce ment was re moved with a high-speed bur, by means of ten move ments, from the api cal to the cer - vi cal re gion. Af ter this pro ce dure, the roots (mesial and dis tal as pects) were scaled and planed with a 5-6 Gracey in stru ment (Hu-Friedy® - USA), by means of 50 ver ti cal ten sion move ments, on the area delimitated by the grooves. Eigh teen 1-mm-thick frag ments mea sur ing 3 x 3 mm were ob tained by means of a low-speed saw (Isomet - USA) with a di a - mond disc, un der deionized wa ter. Expe ri men tal pro ce du res The spec i mens were rinsed with sa line so lu tion and ran domly as signed to three groups with six spec i mens each, re ceiv ing the fol low ing treat - ments: • Group 1 (G1 - con trol group) - scal ing and root plan ing + ir ri ga tion with sa line so lu tion; • Group 2 (G2) - scal ing and root plan ing + Er:YAG la ser (2.94 µm) ir ra di a tion (Kavo Key La ser - KaVo - Ger many) with the fol low ing pa - ram e ters: 100 mJ/47 mJ (cor re spond ing to a 57% trans mis sion fac tor), 10 Hz, 15 sec onds of ir ra di a tion in a to tal of 150 pulses, 0.57 J/cm2, fol lowed by ir ri ga tion with 10 ml of sa line so lu - tion. • Group 3 (G3) - scal ing and root plan ing + Er:YAG la ser (2.94 µm) ir ra di a tion (Kavo Key La ser - KaVo - Ger many) with the fol low ing pa ram e ters: 140 mJ/83 mJ (cor re spond ing to a 57% trans - mis sion fac tor), 10 Hz, 15 sec onds of ir ra di a tion in a to tal of 150 pulses, 1.03 J/cm2, fol lowed by ir ri ga tion with 10 ml of sa line so lu tion; The G2 and G3 spec i mens were ir ra di ated with the Er:YAG la ser (2.94 µm), with a pulse width vary ing from 250 to 500 ms, with a 2,056 handpiece and fi ber di men sions of 1.65 x 0.5 mm, with a trans mis sion fac tor of 57%, fo cused, with - out con tact (0.5 mm) with the fi ber, which was placed per pen dic u larly to the ir ra di ated sur face, with air/wa ter jet cool ing. The spec i mens were mounted on an iron plat form and sta bi lized with a dou ble-face ad he sive tape for Er:YAG la ser ir ra di a - tion. Fol low ing ir ra di a tion, the spec i mens were iden - ti fied and kept in a 2.5% glutaraldehyde in 0.1 M buf fered phos phate so lu tion (pH 7.4) for a min i - mum pe riod of 24 hours. The spec i mens were then cleansed by means of three ir ri ga tion cy cles with 10 ml of a 0.1 M buf fered phos phate so lu tion. They were sub mit ted to a se quen tial de hy dra tion pro - cess with 70% al co hol (10 min utes); 80% al co hol (10 min utes); 90% al co hol (10 min utes) and 100% al co hol (10 min utes). The spec i mens were then dried at room tem per a ture to en able the sput ter ing pro cess with gold, with 99.9% vac uum pu rity. Sput tering was car ried out by means of a spe cific equip ment (Baltec - SCD - 050) set for 120 sec - onds, which pro duced a 25-nm gold film. The spec i mens were then po si tioned for SEM anal y sis with 20 Kv (Philips - EDAX). 309 The o do ro LH, Gar cia VG, Hay pek P, Ze zell DM, Edu ar do C de P.Morp ho lo gic analy sis, by me ans of scan ning elec tron mi cros copy, of the ef fect of Er:YAG la ser on root sur fa ces sub mit ted to sca ling and root pla ning. Pes qui Odon tol Bras 2002;16(4):308-312. RESULTS Group 1 The root sur faces from this group pre sented an ex posed dentinal layer; mod er ate smear layer was ob served in one spec i men and five spec i mens pre - sented in tense smear lay ers with ev i dence of opened dentinal tu bules (Fig ure 1). Group 2 Five spec i mens from this group pre sented no smear layer on the dentinal root sur face as well as to tally closed dentinal tu bules. One spec i men pre - sented par tially closed dentinal tu bules. The an a - lyzed sur faces pre sented ir reg u lar i ties and were char ac ter ized by the pres ence of superposed flaky ar eas with ab sence of grooves, frac tures, cracks, fu sion or char ring in all spec i mens (Fig ure 2). Group 3 The spec i mens from Group 3 were the most uni form, when com pared with those of the other groups. All the an a lyzed spec i mens pre sented the same char ac ter is tics: ab sence of smear layer and to tally opened dentinal tu bules. They pre sented ir - reg u lar sur faces with superposed flaky ar eas, with out grooves, cracks, frac tures or char ring, but the pres ence of ex posed dentinal tu bules was uni - form in all spec i mens (Fig ure 3). DISCUSSION Based on the anal y sis of the re sults we could note that, in G1 (con trol) spec i mens, which were man u ally scaled and root planed with man ual curettes, there was in tense smear layer for ma tion. The pres ence of striation caused by man ual in - stru men ta tion (Fig ure 1) is in to tal ac cor dance with pre vi ous find ings of other authors1,2,25,26. Re gard ing the groups treated with Er:YAG la - ser, we could ob serve that G2 spec i mens pre - sented with an ir reg u lar as pect (with el e va tions and de pres sions, both in the same ori en ta tion) due to the ex plo sive ab la tion caused by la ser ir ra di a - tion. In G3, the uti lized ir ra di a tion pa ram e ters were ca pa ble of re mov ing the smear layer from the root sur face, and all spec i mens pre sented ex posed dentinal tu bules with out intratubular smear layer (Fig ure 3). This fact dem on strates the great ef fec - tive ness of the en ergy ap plied on G3 – it was more able to ex pose dentinal col la gen fi bers, com pletely re mov ing the smear layer. Ac cord ing to some au - thors, that might be an im por tant fac tor in the in - ser tion of new col la gen fibers1,2,26. 310 The o do ro LH, Gar cia VG, Hay pek P, Ze zell DM, Edu ar do C de P. Morp ho lo gic analy sis, by me ans of scan ning elec tron mi cros copy, of the ef fect of Er:YAG la ser on root sur fa ces sub mit ted to sca ling and root pla ning. Pes qui Odon tol Bras 2002;16(4):308-312. FIGURE 1 - Group 1: root sur fa ce with re gu lar as pect, strong pre sen ce of sme ar la yer and evi den ce of ope ned den ti nal tu bu les. FIGURE 2 - Group 2: root sur fa ce with ir re gu lar as pect, ab sen ce of sme ar la yer and par ti ally ope ned den ti nal tu - bu les. FIGURE 3 - Group 3: root sur fa ce with ir re gu lar as pect, re sem bling su per po sed tis sue la yers, ab sen ce of sme ar la yer and com ple tely ope ned den ti nal tu bu les. Through elec tron micrographic anal y sis, it was pos si ble to ob serve that al though la ser was ef fec - tive in re mov ing the smear layer, it is clear that its ac tion on root sur face dentin pro duced an ir reg u - lar as pect (Fig ures 2 and 3), prob a bly due to ab la - tion, al though char ring, cracks and frac tures were not ob served. That has also been re ported by other authors5,15,16,21. The uti li za tion of la sers to pro mote scal ing and root plan ing has arisen many con tro ver sies. Some stud ies with Nd:YAG la ser have dem on strated that ir ra di a tion of root sur faces with cer tain wave - lengths pro motes the for ma tion of cracks, fis sures, crat ers and fu sion of the min er al ized surface14,22, spe cially when la ser is used with in ad e quate ir ra - di a tion pa ram e ters. On the other hand, the lit er a ture has shown, in sev eral stud ies, that Er:YAG la ser has many ad - van tages when com pared with Nd:YAG la ser, spe - cially when ap plied to min er al ized tis sues. Among other ex plo sive ab la tion la sers, Er:YAG is the most res o nant to min er al ized sur faces. This fact is due to the high de gree of wa ter ab sorp tion of its wave - length (2.94 µm). This la ser acts on min er al ized tis sues by va por iz ing their wa ter, caus ing mi - cro-ex plo sions and ejec tion of tis sues (ex plo sive ab la tion) with less ther mal dam age, spe cially when it is used with an air/wa ter cool ing system15,21,27. Many pa pers have re ported the high bac te ri - cidal ef fect of high-in ten sity la sers on periodontal patho genic bac te ria, con firm ing that high-in ten - sity la sers may act as coadjutant in stru ments in periodontal therapy3,7,17. This fact is prob a bly due to the fact that la ser ir ra di a tion pro motes the va - por iza tion of the wa ter pres ent in the cy to plasm of bac te ria, thus caus ing cell rup ture. The scal ing and root plan ing pro ce dure is of ten not enough to elim i nate the toxic agents from root sur faces, such as the outer and in ner tox ins from bac te ria, which are the main rea son for periodontal dis ease with de struc tive char ac ter. Thus, sev eral chem i cal agents, such as cit ric acid, tet ra cy cline and EDTA, were in tro duced with the aim of remo - ving tox ins and re duc ing the num ber of bac te ria on the root sur face. How ever, clin i cal stud ies have dem on strated that the uti li za tion of these chem i cal agents has no sig nif i cant ef fect on the heal ing pro - cess of periodontal tissues11,12,13. In this study, it was pos si ble to ob serve that Er:YAG la ser is ca pa ble of re mov ing the de bris, which are the prod ucts of scal ing and root plan ing (smear layer). How ever, it does not pro mote root sur face smooth ing. In fact, it pro duces a more ir - reg u lar sur face. It is not clear, in the lit er a ture, if this ir reg u lar sur face in ter feres with the events re - lated to the heal ing of periodontal tis sues. CONCLUSIONS From the re sults pre sented in this study, it is pos si ble to con clude that: 1. the Er:YAG la ser-ir ra di ated root sur faces pre - sented, in both uti lized pa ram e ters, a more ir - reg u lar as pect, when com pared to the con trol group (with out Er:YAG la ser ir ra di a tion). How - ever, non of the spec i mens pre sented with cra - ters, cracks, fu sion or char ring; 2. when the groups ir ra di ated with Er:YAG la ser were com pared, it was ev i dent that there was a more ef fi cient re moval of smear layer, as well as greater ex po sure of dentinal tu bules, in the spec i - mens from Group 3 (87 mJ, 10 Hz, 1.03 J/cm2, 15 s). ACKNOWLEDGMENTS The au thors would like to thank FAPESP (São Paulo State Re search Foun da tion ), grant num ber 97/10823-0, and LELO – Ex per i men tal Lab o ra tory of La sers in Den tistry, School of Den tistry, Uni ver - sity of São Paulo, for the la ser equip ment uti lized in this study. REFERENCES 1. Adri ens PA, Lo es che WJ, De Bo e ver JA. Bac te ri al in va si on in root ce men tum and ra di cu lar den tin of pe ri o don tally diseased te eth in hu mans. J Pe ri o don tol 1988;59:222-30. 2. Aleo JJ, De Ren zis FA, Far ber PA, Var bon co e ur AP. The pre sen ce and bi o lo gic ac ti vity of ce men tum-bound en do to - xin. J Pe ri o don tol 1974;45:672-5. 3. Ando Y, Aoki A, Wa ta na be H, Ishi ka wa I. Bac te ri ci dal ef fect of Er bi um:YAG la ser on pe ri o don to pat hic bac te ria. La sers Surg Med 1996;19:190-200. 4. Aoki A, Ando Y, Wa ta na be H, Ishi ka wa I. In vi tro stu di es on la ser sca ling of sub gin gi val cal cu lus with an Er:YAG la ser. J Pe ri o don tol 1994;65:1097-106. 5. Aoki A, Mi u ra M, Aki ya ma F, Na ka ga wa N, Ta na ka J, Oda J, Wa ta na be H. In vi tro eva lu a ti on of Er:YAG la ser sca ling of sub gin gi val cal cu lus in com pa ri son with ul tra so nic sca - ling. J Pe ri o dont Res 2000;35:266-76. 6. Ba ker PJ, Rotch HA, Trom bel li L, Wi kes jo UME. An in vi tro scre e ning mo del to eva lu a te root con di ti o ning pro to cols 311 The o do ro LH, Gar cia VG, Hay pek P, Ze zell DM, Edu ar do C de P.Morp ho lo gic analy sis, by me ans of scan ning elec tron mi cros copy, of the ef fect of Er:YAG la ser on root sur fa ces sub mit ted to sca ling and root pla ning. Pes qui Odon tol Bras 2002;16(4):308-312. for pe ri o don tal re ge ne ra ti ve pro ce du res. J Pe ri o don tol 2000;71:1139-43. 7. Ben Ha tit Y, Blum R, Se ve rin C, Ma quin M, Ja bro MH. The ef fects of a pul sed Nd:YAG la ser on sub gin gi val bac te ri al flo ra and on ce men tum: an in vivo study. J Clin La ser Surg Med 1996;14(3):137-43. 8. Ber ge nholtz A, Ba bay N. Scan ning elec tron mi cros copy of the root sur fa ce tex tu re of ex trac ted pe ri o don tally di se a sed te eth fol lo wing va ri ous et ching and che la ting re gi mens. Int J Pe ri o dont Rest Dent 1996;18(2):171-9. 9. Blom löf J, Blom löf LB, Lind skog SF. Sme ar re mo val and col la gen ex po su re af ter non-sur gi cal root plan ning fol - lowed by et ching with an EDTA gel pre pa ra ti on. J Pe ri o - don tol 1996;67:841-5. 10. Blom fof JPS, Blom lof LB, Lind skog SF. Sme ar la yer for med by dif fe rent root pla ning mo da li ti es and its re mo val by an eth yle ne di a min te tra ce tic acid gel pre pa ra ti on. Int J Pe ri o - dont Rest Dent 1997;17:243-9. 11. Blom lof L, Ber gamn E, Fors gardh A, Foss L, Lars son A, Sjo - berg B et al. A cli ni cal study of root sur fa ce con di ti o ning with an EDTA gel. I – non sur gi cal pe ri o don tal tre at ment. Int J Pe ri o dont Rest Dent 2000;20:561-5. 12. Blom lof L, Jons son B, Blom lof J, Lind skog S. A cli ni cal study of root sur fa ce con di ti o ning with an EDTA gel. II – sur gi cal pe ri o don tal tre at ment. Int J Pe ri o dont Rest Dent 2000;20:567-73. 13. Caf fes se RG, Nasj le ti CE, Ander son GB, Lo pa tin DE, Smith BA, Mor ri son EC. Pe ri o don tal he a ling fol lo wing gui ded tis - sue re ge ne ra ti on with ci tric acid and fi bro nec tin applica - tion. J Pe ri o don tol 1991;62:21-9. 14. Cobb CM, Mccaw ley TK, Kil loy WJ. A pre li mi nary study on the ef fects of the Nd:YAG la ser on root sur fa ces and sub - gin gi val mi cro flo ra in vivo. J Pe ri o don tol 1992;63:701-7. 15. Fol waczny M, Mehl A, Haff ner C, Benz C, Hic kel R. Root subs tan ce re mo val with Er:YAG la ser ra di a ti on at dif fe rent pa ra me ters using a new de li very sis tem. J Pe ri o don tol 2000;71:147-55. 16. Fu jii T, Ba eh ni PC, Ka wai O, Ka wa ka mi T, Mat su da K, Ko was hi Y. Scan ning elec tron mi cros co pic study of the ef fects of Er:YAG la ser on root ce men tum. J Pe ri o don tol 1998;69:1283-90. 17. Gutk necht N, Fis cher J. Bac te ri al ef fect of the Nd:YAG in la ser-sup por ted cu re ta ge. Int Sim po si um on Bi o me di cal Optics 1997;6:2973-9. 18. Hat fi eld CG, Ba um ham mers A. Cyto to xic ef fects of pe ri o - don tally in vol ved sur fa ces of hu man te eth. Arch Oral Biol 1971;16:465-8. 19. Hi gas hi T, Oka mo to H. The ef fect of ul tra so nic ir ri ga ti on be fo - re and af ter ci tric acid tre at ment on col la gen fi bril ex po su re: an in vi tro SEM study. J Pe ri o don tol 1995;66:887-91. 20. Isik AG, Ta rim B, Ha fez AA, Yal cin FS, Onan U, Cox CF. A com pa ra ti ve scan ning elec tron mi cros co pic study on the cha rac te ris tics of de mi ne ra li zed den tin root sur fa ce using di ffe rent te tracy cli ne HCl con cen tra ti ons and ap pli ca ti on ti mes. J Pe ri o don tol 2000;71:219-25. 21. Isra el M, Cobb CM, Ross mann JA, Spen cer P. The ef fects of CO2, Nd:YAG and Er:YAG la sers with and wit hout sur fa ce co o lant on to oth ro ots sur fa ces. An in vi tro study. J Clin Pe - ri o don tol 1997;24:595-602. 22. Ito K, Nis hi ka ta J, Mu rai S. Effects of Nd:YAG laser radia - tion on re mo val of a root sur fa ce sme ar la yer af ter root pla - ning. A scan ning elec tron mi cros co pic study. J Pe ri o don tol 1993;64:547-52. 23. Kel ler U, Hibst R. Expe ri men tal re mo val of sub gin gi val cal cu - lus with the Er:YAG la ser. Proc. SPIE 1987;2623:189-98. 24. Laf ferty TA, Gher ME, Gray JL. Com pa ra ti ve SEM study on the ef fect of acid et ching with te tracy cli ne HCl or ci tric acid on ins tru men ted pe ri o don tally-in vol ved hu man root sur fa - ces. J Pe ri o don tol 1993;64:689-93. 25. Pash ley DH. Sme ar-la yer: physi o lo gi cal con si de ra ti ons. Oper Dent 1994;3:13-29. 26. Pol son AM, Ca ton J. Fac tors in flu en cing pe ri o don tal re pa ir and re ge ne ra ti on. J Pe ri o don tol 1982;53:617-25. 27. Scho op U, Mo ritz A, Ma les chitz K, Go hark hay K, Klu ger W, Wer nisch J, Sperr W. The im pact of Er:YAG la ser irradia - tion on root sur fa ces: an in vi tro eva lu a ti on. J Oral La ser Appli ca ti ons 2001;1:35-41. 28. Schwartz Z, Loh mann CH, Wi e land M, Coch ran DL, De anm DD, Tex tor M, Bo ne vald LF, Bo yan BD. Oste o blast pro li fe ra - ti on and dif fe ren ti a ti on on den tin sli ces are mo du la ted with te tracy cli ne or os te o clasts. J Pe ri o don tol 2000;71:586-97. 29. Schwartz F, Scu le an A, Ge org T, Re ich E. Pe ri o don tal tre at - ment with an Er:YAG la ser com pa red to sca ling and root pla - ning. A con trol led cli ni cal study. J Pe ri o don tol 2001;72:361-7. 30. Trom bel li L, Sab bia A, Zan ga ri F, Gri sel li A, Wi kes jo UME, Ca lu ra G. Effect of te tracy cli ne HCl on pe ri o don tally af fec - ted hu man root sur fa ces. J Pe ri o don tol 1995;66:685-91. Recebido para publicação em 17/10/01 Enviado para reformulação em 16/04/02 Aceito para publicação em 05/08/02 312 The o do ro LH, Gar cia VG, Hay pek P, Ze zell DM, Edu ar do C de P. Morp ho lo gic analy sis, by me ans of scan ning elec tron mi cros copy, of the ef fect of Er:YAG la ser on root sur fa ces sub mit ted to sca ling and root pla ning. Pes qui Odon tol Bras 2002;16(4):308-312.