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Use of the SupraperiostealEnvelope in Soft Tissue Graftingfor Root Coverage. I. Rationaieand Tectinique

AndTew L. Allen. DMD'

Recent advances in graft procurement and suturing encourage areassessment of the "envelope ~ techinique in soft tissue grafting for rootcoverage. Use of the supraperiosfeal envelope permits conservation ofexisting gingivo, minimal surgical trauma to tfie recipient area, and firmfixation of tfie connective tissue graft over singie and multiple adjacentareas of recession. The intimate coaptafian of the bilaminar soft tissuecomplex thus achieved may facilitate graft survival and postaperativeblehding of soft tissues. (Int J Periodont Rest Dent 1994;14;217-227,)

*Private Practice in Periadontics, Brunswick, Maine,

Correspandenoe fa; Andrew Alien, DMD. 117 Pleasant Street,Brunsv/ick, Maine D4DH

The search for predictabie clini-cal solutions to the probiem ofgingivai recession has led tosevero i important surgicoladvances this past decode.The free autogenous gingivalgraft, once used primarily foraugmentation of existing gingi-va, has shown increased pre-dictabiiity for root coverage, asdescribed by Miller̂ '̂ and oth-ers,- '̂' Exacting specificationsfar graft shape and thickness,recipient site preparation, andsuturing appeared to increosethe abiiity of the subjacentperiosteal bed to provide anutrition "bridge" to that por-tion of the graft over the rootsurface. Miller's success wosindeed remarkable whenviewed in the context of pre-vaiiing ciinical opinion, which,with the notabie exception ofone case report,^ heid that gin-givai grafts usually foiled whenplaced over previously ex-posed root surfaces,*-^

The free gingivoi graft forraot coverage is a one-stageprocedure, independent of the

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quaiity or quantity of the gingi-val tissue odjacent to therecession. As such, it hasodvantages over the gingivalgroft-ooronaiiy positioned flapand pedicle flap approochesto the treatment of gingivolrecession.'-'^ The gingivai graftmust be used with caution inestheticaiiy sensitive areasbecause of inconsistent ooiorblending of the graft with adja-cent gingival tissues.""̂

Free connective tissuegrafting for root coveragecombines on overlying fiapond an underlying vascuiarbed for graft nourishment. Thebiiaminor blood supply thuscreated may more closeiyopproximate that of the pedi-cie flap whiie retaining theodvontoge of the gingivaigroft in oontroiiing donor tissuechoraoteristios.

Langer ond ooworkers'°'"developed the subepitheliaiconnective tissue graft tech-nique for use in both isolatedand multiple adjacent areas otrecession. The outhors hopedto inorease predictabiiity forroot coverage in areas ofwide-deep recession frequentlyfound in the maxilla.'° A "trapdoor" flap was created in thepalate for procurement of oconnective tissue graft, whichwos coronaiiy positionedbetween o partiqi-thickness

flap and underlying periosteum.The harvesting technique pro-duced a strip of palatql epithe-iium an the superficial edge ofthe graft, which was retainedfor use as marginal tissue inareas of recession. Thisapproach resulted in iesspalatal denudation and amore esthetic color blending inthe recipient area when com-pared to gingival grofting tech-niques for root coverage, Apossible disadvantage is thehigh degree of technicai profi-ciency necessary to sufure thegraft and the fiap in a ciinicoilyacceptab le relationship foeach other and to the recipi-ent site.

Raetzke^^ described theenveiope technique for use incovering isoiated areas of rootexposure. After excising a col-lor of tissue and preparing theraat surface, a partíai-thioknessenveiope was creoted withinthe tissue adjacent to the qreoof recession, A semiiunarwedge of fissue from thepaiate was then ploced withinthe enveicpe and secured withcyqnoacryiate. No sutureswere used. The author listedseverqi advantages, inciudingminimai surgiool trouma andesthetic blending of tissuespostoperativeiy. Roetzke advo-cated use of the enveiope iniooaiized areas only, and

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reported difficuity in obtainingsufficient tissue for use in moreextensive areas of recession.

Neison'3 employed a sub-pedicie approach to connec-tive tissue gratting tor root cov-erage, Uniike Langer andLanger,'° he piaced fuli-thick-ness pedicle flaps over connec-tive tissue grafts to enhancenutrition where they contactedareas of recession. Nelsondescribed the subpedicle tech-nique as more difficult and timeconsuming than others, butexpressed optimism for futureuse of bilaminar soft tissue graft-ing in periodontal practice.Harris''' reported using partiai-thickness pedicie flaps in a simi-ior manner. He also introduceda scalpel handle with parallelblades as an aid in graft pro-curement, Jahnke et ai '^ re-cently suggested that connec-tive tissue autografts achievedgreater root coverage than dothick gingival grafts. The authorsempioyed a single horizontoiincision in preparation of therecipient site.

Most bilaminar techniquesfor root coverage use both hor-izontal and vertical incisions toprepare the recipient site andrather complex suturing tech-niques for graft placement andfixation.'°-'^-'''' in contrast, therecipient enveiope, as de-scribed by Raetzke,'^ appearsboth simple and elegant—no

incisions, no sutures, and min-imal surgical traumo. Unfor-tunateiy, its use has beeniimited to isolated areas ofrecession oniy. In oddition,enveiope preparotion beganwith excision of a coiiar of gin-givai tissue "corresponding tothe sulcus depth," which mayhave resuited in excessive sac-rifice of existing tissue and sup-porting vasculature. These limi-tations may account for its postexclusion trom discussions of bi-laminar connective tissue graft-ing techniques with wider clini-cal application,'^'"'*

Based on these reports,moditications were sought thatwould simplify procedurestectinically while respectingsuccessful surgicai principlesdeveloped by previous au-thors. The purpose of the firstpart of this report is to describethe rationale and technique foruse of the supraperiostealenvelope to inciude multipieadjacent areas of recession.Modifications in envelopedesign and suturing will be pro-posed, discussed, and ciarifiedwith illustrations,

indioations for use of thesupraperiosteal enveiope tech-nique are as toflows:

1, Minimai probing depthsat recipient sites

2, Presence of Miller Ciass Iand II recession

3. Inadequate tissue quaiityor quantity for iaterai pedicleor other single-stage flap pro-cedure confined to one opera-tive site

4. Single or muitiple adja-cent areas of recession

5. Gingival clefts or irregularmargins compromising esthet-ics, eral hygiene effectiveness,or thermal sensitivity

Contraindications for its useinclude the foiiowing:

1. Habitual use ot tobaccoor other systemic influencesknown to oomprcmise healingpotentiai

2. Periodontol pockets orosseous defects in recipientarea requiring flap elevationfor access ond visibility

3. Inadequate connectivetissue donor site

4. Presence of Miiier Class IIIor IV recession

5. Previous damage to rootsurfaces incompatible withpostoperative soft tissue health

Ó, Aberrant freno in recipi-ent area

Aberrant frena connot becorrected at the time ofsurgery because incisionswouid compromise the bioodsupply availabie to the graft.When indicated, a frenectomyis scheduied 4 to 6 weeks priorto grafting.

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Method and materials

Recipient site

moistened gauze is placedaver the recipient site while thedonor tissue is prooured.

Initially, an internal beveiledinoision is performed to enableuse of a sharp ouret for enucle-ation af the sulculor epifheiiumadjacent tc areas of recession.When marginal tissues are thinand friabie, curets are em-ployed exclusiveiy for sulcuiardebridemenf. Care must betoken to conserve as muchgingival tissue os possible tohelp nourish the graft. Exposedroot surfaces are root pianedunder copious saline irrigationto remove bncteriol contami-nonts ond reduce root convex-ity, thus decreosing avascuiarsurface orea under the graff.As fissue thickness permits,sharp dissection is used to fcrma parfiai-thickness supraperi-osteal envelope exfending 3 fo5 mm Interally and apically toareas cf recession, undermin-ing infermediate popillae (Fig1). Preparation of papiiiaryareas adjacent to remainingroot convexities may be facili-tated by gently elevating thetissue while dissecting laterallywith a small surgical blade(Bard-Parker 15C; BecktonDickinson) (Fig 2). Thin gingivarequires careful full-thicknesseievotion to ensure tissue viabil-ity aver the graft, A foii tem-piate can be fabricated toapproximate the size of theenvelope for later use, Saline-

Donor site

Connective tissue graff pro-ouremenf hos been describedby several authors,"^-'" Raetz-ke'^ has advacated graduaiiyconverging semiiunar incisionsfo define a paiatal graft ofdesired thickness and oonfcur.This approach is used for iso-lafed areas af recession. Thepaiatai fiap described by Lon-ger and Langer^° is used forgraft procurement when two ormore adjacent areas of reces-sion are fo be treated.

Unforfunately, geneficoliythin gingiva, which predisposesto faciai mucogingivoi defects,often seems to be reflecfed inthe characteristics ct thepaiotal mucosa, in these in-stances, the most productivepalatal area for connective tis-sue graft procurement occurs 2to 4 mm apical to the marginalgingiva from the mesiai aspectof the paiafal raat of the firsfmolor forward to the oanine.'^

Typicaiiy, the ccronal 3 to 5mm of the graft will be com-posed of dense lamina propria,while the apicai portion willcontain iaosely organized sub-mucosoi eiements. The graftincluding the submucosa isplaced between saline-moist-ened gauze squores while thepaiatai donar area is sutured.

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Fig 1 facial view of odjooeni areas atreoessioh. Internal bevelled ihoinonswere used to remove sulcular epitheli-um, retaining as much gingiva os possi-ble. Diogonol lines indicate approxi-mate dimensions af the supraperiosteolenvelope

Fig 2 Cross section of odjacent oreosof recession. Gentle elevation ofpopil-lary tissues aids sharp dissection adja-cent to remaining root convexities.

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Graft placement and suturing

The graft is pioced over therecipient enveiope or foii tem-plate, and evaiuated andrecontóured as necessary. Themesiodistal dimension shouldpermit slight tension on thegraft after sufuring, and thusshould be 1 to 2 mm less thanthat of the enveiope. Uniformthickness is established with aminimum of 1,5 mm over rootsurfaces. Graft borders arebeveiled where they wiil besubmerged in the enveiope,facilitating cooptation of thebilaminar soft tissue compiex tothe underiying periosteai bed,Keratinized epitheiium is usuallyremoved, but may be retainedin oreos that wiii remainexposed when the graft is inposition. The graft iamina pro-pria is positioned over the rootsurface where a zone of gingi-va is desired; submucosal ele-ments are submerged withinthe envelope apicai to the gin-givai zone, A mattress sutureplaced in one end of the graftis heipful in guiding the graftunder intermediate papiiiae(Fig 3). A small suturing forceps(Corn suture pliers, SP 20, Hu-Friedy) is used to place a 5-0guf suture 3 to 5 mm from thedistal edge of the graft prior toinsertion into the envelope.Tissue borders are gentlyteased inta the enveiope usinga tissue forceps and a packinginstrument (gingivai marginpocker, serrated #lóO8N, FA

Beck), Once the graft is in posi-tion, the distai suture is com-pieted. The mesiai aspect isthen sutured in a similar mon-ner, introducing siight tensionwithin the groft (Fig 4),Intermediate papii iae areanchored with vertical mattresssutures to ensure firm fixation ofthe graft within the enveiope(Figs 5 and ó). Pressure isappiied with moistened gauzefor 5 minutes to facil i tatehemostasis with minimai clotthickness. Buriew foii (Schein) ispiaced over the graft area anda naneugenoi dressing (CoePac, Schein) is appiied to bothdonor and recipient sites.Postoperative care paraileiscomparabie mucogingival pro-cedures.

Discussion

Habituai use of tobacco (smok-ing) is iisted as a controindica-tion to the use of the supra-periosteai enveiope. Althoughcontrary evidence is avaii-abie,"" most agree that thelocal and systemic effects ofsmoking are deleterious to peri-odontal heaith and heal-ing.'^.i? The supraperiasteaienveiope, as with mast muco-gingival procedures for rootcoverage, requires optimaihost response for successfuihealing. Hence, a strict ban onuse of tobacco is advised.

The enveicpe design is con-traindicated in the presence af

periodontal pockets or osseousdefects. Elimination of horizon-tai and verticai incisions in therecipient site iimits visibiiity andaccess to other periodontalpathology that may be pres-ent.

Miller hos been o strongadvocate far the use of citricacid treatment of the root priorto soft tissue grafting.^'^ Whilehis rationale has been com-pelling, others have not foundefficacy for its routine use inhumans,^° Resuits of correctivesoft tissue surgery on convexroot surfaces highly accessibieto effective daiiy orai hygienehave not yet convinced theouthor of a need for its use.

Partiai-thickness shorp dis-section is used in the recipientarea to prepare the supro-periosteai enveiope. Whiieperiosteai retention over inter-proximal bone does notappear necessary for osseouspreservation,^! it may faciiitateinitiai revascularization of theoveriying connective tissuegraft, Caffesse et al^^ com-pared the healing of gingivaigrafts when piaced on a recipi-ent bed of either denudedbone or retained periosteum.The comparison reveoled thatdenuded cortical bone under-went an initiai resarption,deiaying vascuiar proiiferaficnin the eariy stages of healing.Although these findings maynot fuily apply to biiaminargrafting, prompt initiai revascu-larization may be facilitated by

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Fig 3 Connective tissue groft with bev-elled edges is teased into envelopeusing a mattress suture and a pockinginstrument

Fig 4 The connective tissue graft, con-toured slightly shorter than the enve-lope, is first secured with o distal suture.The mesiol suture is completed, creat-ing siight tension within the groft.

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Fig 5 tnfermediote papilla is onohoredwith o vertical mattress suture. Arrowsindicate slight mesiadistal tension.

Fig 6 Faciot view of the connective tis-sue graft sutured into position overodjacent oreas af recession.

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partial-thickness preparation.Nelson,!^ however, hos reportedexcelient resuits using fuii-fhick-ness tiap coveroge of graffs.Consequentiy, tuii-fhickness eie-vafion is recommended for usein farming the enveiope whengingiva is thin, friabie, or iikeiy tonecrose if subjected to partiai-thickness dissection.

Design of fhe envelopepermits elimination of custom-ary horizontal and verticalreleasing incisions, resulting inmobilization of papillary andlateral blood supplies to fheoverlying gingiva. Will this addi-tionol blood supply increasethe potential far graff survivai?

Mormann and cowark-g|.s23.24 have clearly demon-strated that the anterior gingi-val tissues receive their majorsource cf perfusion in an api-cocorcnai direction. Cus-tomary incisions, therefore,would seem to have littleeffect on the bicod supply tocommonly encountered recipi-ent areas. Several reports, how-ever, suggest that papillaryand loterai biood suppiies maycontribute substantiaily to gin-gival pertusion.2'2^- '̂

Tornow^s was abie to ooro-nolly position existing gingivasuccessfuily over multiple odja-cent areas ot recession byreleasing tissue with continuoushorizontai semilunar incisicns

severing the apicocoronalbiood suppiy within attachedgingiva and below the area ofrecession. Sumner,^'' using asimiiar technique for treatmentof recession on maxiiioryConines, stated that the coro-naliy positioned gingiva sur-vived "by its continued con-nection To the mesiai and distaitissues." Miller̂ has advocated"butt joint" junctions with thepapillary and laterai tissues asimportant factors in gingivaigraft survivai. More recentiy,Tinti et al^' reported successusing a semilunar horizontaiinoision ta reiease tissues coro-naily over microporous mem-brones covering areas otrecession. These reports sug-gest that lateral and, to a lesserextent, papiiiary biood suppiieshave clinical signiticonoe andtheretore may enhance graffnutriticn within the supraperi-osteai enveiope.

Envelope design does notpermit corona! positioning ofgingival tissues over the graft.Bilaminar flap ond pedicle pro-cedures bolster nutrition to thegraft by coronally positioningexternal gingival tissues.Whether this advantage is off-set by increased biood suppiyfrom iaterai and papillary tis-sues is unknown. Clearly, intactpapiiiary tissues permitted bythe enveiope design promote

ease of suturing, firm graft íixa-tion, and maintenance ofanterior esthetics.

The paiotol zone betweenthe maxillary firsf molar and thecanine is advocated far opti-mol graft horvesfing. Denseconnective tissue is frequenfiymore pientiful and uncompro-mised by palatal exostosesoften encountered close to thesurtace further posterioriy.Submucosai elements are aisopresent in this areo. A bal-anced combination of thesetwo connective tissue compo-nents within the graft may actsynergisticaily in the recipientsite to produce optimal results.

Severai reports^^^ç hoveindicated that surface kera-tinizotion is directed by theunderlying connective tissue.Theretore, the graft must con-tain dense iamina propriaooronaiiy to produoe fully kera-finized tissue in fhe "gingivaizone" of the recipient area.The opioal portion of the graftoften contoins submucosai ele-ments that ore submergedwithin the envelope.

The submucosa ond con-tiguous deep connective tis-sues moy contribute to oriticalearly heoiing events.^^'^^ Ca-iura et oP° credit the abundantnumber of capillaries in thedeeper iayers ot the graft lami-na proprio for the presence of

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valuable nutrients and promptreestablishment of circuiation,in his discussion of fuii-thicknessoniay grafts, Seibert'^ has sug-gested that the looseiy orga-nized adipose and glanduiartissue of the submucosa mayreadiiy accept piasma diffusionand capiiiary ingrowth, foster-ing prompt revascularizationond graft survival, Additionaiiy,vi/hen combined with the over-lying lamina propria in a fuil-thiokness graft, the submucosamay enhance a return to fuiivascularity and esthetic coiorbiending with adjaoent tissues.Current graft procurementtechniques may be used tohorvest appropriate ratios oflamina propria and submucosato produce the desired re-

Bevelled graft edges areadvocated for use within thesupraperiosteai enveiope.Although "butt joint" relation-ships in the recipient siteappeor to foster gingivai graftsurvivai, the enveiope designinvites beveiied edges toensure intimate biiaminar con-tact of the invoived tissues.Raetzke^^ has recommendedgraduaiiy converging semilunarincisions for use in procuringpalatal donor tissue for isolatedareas of recession. The resultingsemiiunar shape seems taadapt well in the recipientenvelape. The Langer procure-

ment approach^*^ is used whenmuitipie odjacent areas ofrecession are present, becausegraft thickness ond contourseem more difficuit to oontroiwhen attempting semiiunarincisions with ionger grafts. Theparaiiei biade handle intro-duced by Harris''' holds promisefor consistent graft harvesting,in these instances, graft bevei-iing is accompiished after pro-curement from the paiate.

A minimum graft thicknessof 1.5 mm over root surfaces iscompatibie with previous rec-ommendations.''''^•''' Graftthickness may be increased inwide areas of recession asdeemed appropriate to clini-cal circumstances and tissuesurvivai. As indicated by Langerand Langer,'° second-stagegingivopiasty is a predictabiechoice if resuitant contours areunsatisfactory.

Graft design and suturingtechniques create slight ten-sian on the tissue at comple-tion. Hoibrook ond Cschen-bein^ have reported thattension thus induced may facii-itate anastomosis of vessels inthe recipient site with those offhe graft, Raetzke'^ advocatedthe use of a tissue adhesive forgraft fixation. The use of cyano-acrylafe would result in a pas-sive reiationship between thegraft and the enveiope. Moreresearch is indicated ta clarify

the effect of graft "stretching"on eariy heaiing events andgraft survivai.

The rationale for use of thesupraperiosteai envelope in softtissue grafting for root coveragehas been discussed in detaii.Surgicai modifications havebeen proposed that simplifytechniques whiie retainingeiements responsibie far suc-cess, indications have beenexpanded to include muitipieadjacent areas of recession.The supraperiosteai envelopeappears to have severaladvantages in the treatment ofrecession when compared tobiiominar flap and pedicieapproaches;

1, Surgicai trauma to therecipient area is minimai.

2. Graft nutrition is aug-mented by mobilization of iater-ai and papiiiary vascuiar sup-piies from adjacent overiyinggingiva,

3, integrity of invoived papil-iae is maintained, favoringpreservatian of esthetics.

4. Envelope design permitsreiative ease of suturing whiieensuring firm graft fixation andconfinement within the recipi-ent site.

More research is needed tocompare resuits and furtherdelineate indicatians for variousbiiaminar approaches currentiyin use.

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References

l.rviiller PD Jr Root coveroge using afiee soft tissue autogroft followingcitric acid application. I. Technique.Int J Periodont Rest Dent 19e22(l)'65-70,

2. Miller PD Jr, Root coverage using thefree saft tissue autograft followingcitric acia applicoticn. III. A success-ftjl and predictable procedure inareas at deep-wide recession. Int JPeriodont Rest Dent 1985,5(5): 14-37.

3. Holbroak T, Oschenbein C. Com-plete coverage oí the denudedroot surface with a one-stage gingi-val graft. Int J Periadont Rest Dent19S3;3C3):9-27.

4.Tolmie PN, Rubins RP. Buch GS.Vagianos V, Lanz JC. The pre-dictability of raot coverage by wayot free gingival autogratts and citricacid application: An evaluation bymultiple clinicians, Inf J Penodontol1991;11:261-271.

5. Livingston HL Total coverage of mul-tiple and adjacent denuded rootsurfaces with a free gingival auto-graft. J Periodontol 1975,46 209-210.

6. Hawley CE. Staffileno H. Clinicolevaluation of free gmgivol grafts inperJodontal surgery. J Periodontol1970;41:105-l]2.

7. Bernimoulin JP, Luscher B, Muhie-mann HR, Coronally repositionedperiodontal flap. Clinical evaluofionatter one yeai. J Clin Periodontol1975;2:1-13.

8. Hall WB. Pure Mucogingival Pro-b-lems. Ch icago : Quintessence,1984:132.

9. Grupe H, Warren R. Repair of gingi-val defects by a sliding flop opera-tion. J Periodontol 1956j27:92.

10. Langer B. Langer L Subepithelialconnective tissue graft techniquefar root coveroge. J Periodontol19e5;56:715-720.

11. Langer B. Calagna LJ. The subep-ithelial connective tissue graft. Anew approoch to the enhance-ment of anterior cosmetics. Int JPeriodont Rest Dent 1982:2:22-34.

12 Raetzke PB. Covering local izedoreas of root exposure employingthe envelope techn ique, jPeriodontol 1985:56:397-402.

t3. Nelson SW, The subpedici© connec-tive tissue groft—A bilaminar recon-structive procedure for the cover-age of denuded root surfaces. JPeriodontol 1987:58.95-102,

14 Harris RJ. The connective tissue andpartiai-thickness double pediclegraft' A predictable method ofobtain ing toot coverage. JPeriodontol 1992:63:477-486.

15 Johnke PV, Sandifer JB, Gher ME.Gray JL Richardson CA. Thick freegingival and connect ive tissueauthografts for root coverage. JPeriodontol 1993.64:315-322

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17. Seibert JS. Reconstruction ofde formed, poftial ly edentulousridges, using full-thickness onlaygrafts Part I. Techniaue and woundhealing Compend Contin EducDentl9a3:<3:437-453.

18. Miller PD, Root coverage with thefree gingivoi graft. J Periodontol1987:58:674-081,

19. Akef J, Weine FS. Weissman DP Therole of smoking in the progression ofperiodohtal diseose: A literaturereview, Compend Cantin EducDent 1992:13 526-530

20. World Workshop in Clinical Perio-dontics, VII (Proceedings of the Sev-enth World Workshop ih ClihicalPeriodontics, 23-27 July 1989,Princeton, NJ), Chicoga: Amer-ican Academy of Periodontology19B9:l-25,

2l ,Widerman tvi, Wenfz F, Orban B,Histogenesis of repair aftermucogingival surgery. J Periodontol1960:31.283.

22. Caffesse RG, Burgeft FG. NasjietiCE. Costelli WA. Healing of free gin-giva/ grafts with and without perios-teum. J Periodontal 1979:50:586-594.

23 tviormann W. Ciancio SG, Bloodsupply of human gingiva fallowingperiodontal surgery—A fluoresceinangiographie study J Periodontol1977:46.681-692,

24. Mormann W. Meier C. Firestone A.Gingival blood circulation afterexperimentol wounds ih man, J ClinPeriodohtol 1979:6:417-424,

25. Tarnow DP. Semilunar coronallyrepositioned flap. J Clin Periodonfol1986,3:182-185.

26. Sumner CF III, Surgical repaii ofrecession on the maxillary cuspid JPeriodontol 1969:40:119-121.

27 Tinti C, Vihcenzi G, Cortellini P, PiniPrato G, Clauser C. Guided tissueregeneration in the treatment ofhuman fooial recession. A 12-caserepoft. J Periodontol 1992:63;554-560.

28 Karring T, Lang NP. Loe H. The roteof gingival connect ive tissue indetermining epitheliol differentia-tion. J Periodont Res 1975:10:1

29. Donn BJ Jr. The free connective tis-sue outograft' A clinical and histo-logie wound heal ihg study inhumans. J Periodohtol 1978:49:253-260.

30. Calura G. Martani G, Parma-Benfenati S, De Paoli S, Lucchesi C,Fugazzotto PA, Ultrasfructural Obser-vations on the wound healing offree gingivoi connect ive tissueautagrafts with and without epithe-lium in tiumahs. Int J Periodont RestDent 1991:11:283-301,

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