The International Journoi of Periodontics & Restorative Dentistry

333

Combined Dentai Implant andGuided Tissue RegenerationTherapy in Humans

Marlin E. Gtier DDS, MEd'George Quintero. DDS"Jot^r)nyB. Sandifer, MS DMD"Michael Tobacco, DDS'"A. C. Richardson. DDS**"

This study evaiuatsd wound heoling and osseointegrotion of dental implants placedin Immediate postextroction sockets in humons. Ten heotthy adults had one or morefeetfi extracted and replaced with ill dentai impiants. which were centered in theresidual socket and covered with a poiytetrafluoroethviene memörone ana o fiap toattain primary closure. Measurements were made to document the relationship oftxne to impiant ot the time of implant piacement ond at the á-monfh reentry. Allimpionts were ciinicaiiy osseointegrated at the 6-month reentry procedure; narrowbony defects showed complete bone nil. whiie wide detects showed partial bone fiii.There wos less bone regeneration in areas of thin corticai bone or preexisting dehis-cences and in impiont sites with eoriy membrane exposure. Implants pioced in imme-diate postextraction sockets demonstrated successtui osseointegration with irregularbone-healing patterns, which were reiated to variations in existing bony onotomy andsocket location. (\nt J Penoüor\\ Rest Deni 1994.14:333-347.)

*CAPT. DC. USf̂ , Chairman. PerJoQontics Department. Noval DenialSchool. Natianai Naval Dental Center. Bethesda. MarylanO 20889-5077.

*»CAPT. DC. USN. Stoff, Periadantics Department. Naval Dental Scfiaal.Natonal Navel Dental Center.

***CAPr. DC. USN, staff. Piosttioaontjcs Department. Maval DentolSchool. Notional Naval Dental Center.

****|CDR. DC. USN. Stoff. Research Department. Noval Denial School.Notianal NGVOI Dentol Center

The opinions or ossertions cantainea herein are those of ttie authorsand are not to be construed as officiol or as reflecting the views of theDeportment of ihe Navy.

Reprint requests tc Ub/orion. Noval Dentol School, NNDC. Betnesda,Moiylond 20889-5077.All ottier correspondence to: CAPT Gher.

Dentai impiants provide a reli-able means of toofh replace-ment that reduces many of fhedisadvanfages noted with con-ventionai prostheses,'"^ Theypermit the use of fixed porfialdentures where natural abut-ments are missing, resulting ingreater comfort and functionfor the patient. For single toothreplacement, dental implantseiiminate the need to use adja-cent teeth as abutmenfs. thusconserving sound tooth sfruc-fure. This therapy may simplifyoral hygiene measures andreduce the esthetic problemsencounfered when areas withdiasfemafo and irregulor toothpositions are resfored. implantsmay also reduce alveolar boneloss, which normaiiy occurs fol-lowing loss of a tooth, and itsstimulating effect on thebone."

Current dental implant-piaoement techniques oail forimpiant sites to be prepared sothat intimate contact Isobtained between the impiantand the olveoiar bone.^ This

Valume 14. Number d. 1W4

334

requires that extraction sites bepermitted to heai for ó to 12months to gain fiii of the bonysocket before surgioai piaoe-ment of the implant. This pro-longs the treotment period ondpermits bone résorption tooccur during heaiing.*'' Pioc-ing the dentai implants ot thetime of extraction hos theadvantages of simpiifying thepositioning of the implant fix-ture due to ovoiloble iand-morks, providing the opportu-nity to ploce impionts in areasthat might otherwise be unsuit-abie for a fixed prosthesis dueto bone résorption, preservingalveoiar bone and ridgeshape, and reducing thepotential for sinus penetrationIn the maxiiiary posterior olvec-iUS. ' " ' "

Recent ciinicai evidenceindicates thot guided tissueregeneration (GTR) techniquesmay be combined with dentoiimpiants, permitting plocementof fhe impiant at the time ottooth extraction.'^-'^ The use ofGTR to exciude the gingivaiepithelium and connective tis-sue cells from the healingextraction site moy leod toenhonced osteogenesis, morecompiete bone fiii, and im-proved osseointegration,'""'''

This study evaiuated thepotentiai for bone tili and thesuccess of osseointegration ofdentoi impiants piaced inimmediate postextractionsockets when combined withGTR in humons.

Method and nnaterials

Study Population

Ten healthy aduits who re-quired extraction of one ormore teeth and repiocementof the teeth with o dentoi pros-thesis and who met the follow-ing criteria were chosen for thestudy:

1. Tooth extraction was indi-coted due to cories. toothfracture, periodontitis. or un-treatable endodontic faiiure.

2. After exfrootion. thetooth socket was large enoughthat o residuol bony defectwcuid remain after piacementof the dental implant.

3. The patient's ccciusionwos conducive to the plannedprosthesis.

4. The patient desiredrepiacement of the tooth orteeth and was oble to complywith the required recoii inter-vols,

Specificaliy excluded fromthe study were patients whowere pregnant and patientswho had any locol or systemicinvolvement that wauid inhibita normai wound-heaiingresponse cr preciude the surgi-cal procedure required topiace the dentai implant or theuse of o GTR barrier mem-brone. Aisc exciuded werepatients whose extraction sitesshewed bone loss that wassevere enough tc prevent ini-tial stobilizafion cf the dentaiimpiant.

Experimental Design

Foilowing initiai diagnosis andtreatment planning, and afterwritten Informed consent wasobtoined, the potients under-went initial theropy to reducethe microbiol flora, estabiish aheaithy periodontium, and pro-vide an environment con-ducive to heaiing.

The patients were givenlocai anesthesia ond mucope-riasteol fiaps were eievotedond the tooth or teeth to beextrocteq were carefuliy re-moved by forceps delivery tominimize troumo to the peri-odontal tissues. The socket wosinstrumented to remove anyodherenf soft tissues. The sock-et depth was meosured fromthe crest at the most coronaialveolor bone to estoblish thelength of the desired dentoiimpiont. The opicai port of thesocket was prepared accord-ing to the manutacturer's pro-tocoi to receive on iTI dentaiimplant (Straumonn). The im-plant was positioned in thecenter of the residuai socket ota uniform distance from thebony socket walis. The dentalimpiont was piaoed with thetop of the impiont approxi-mateiy at the ievei of the exist-ing alveolar crest (Fig 1). Theend of the implant extendedapicaiiy 2 to 4 mm past theapex of the socket.

At the time of implantplacement and ogoin at thesurgical reentry 6 months ioter.

thie International Journal of Periodontics & Restorative Dentistry

335

bone regeneration around thedental implant was docu-mented with radiographs ondwith the following measure-ments: the horizontal distoncetrom the socket wall to theimplont on the mesiai. distal,taciol, and lingual surfaces; thedistance trom the top of theimpiant to the most opioaibase of the residuol socketotter implant placement; thedistance trom the top ot theimplant to the most apioalsooket crest and the distancefrom the top of the implonf tofhe most coronol sockef crest(Fig 2).

Gore-Tex augmentat ionmaterial (GTAM, WL Gore) wasplaced over the dental implantand extended to cover at least3 mm of crestal bone on thefaoiai and iingual surfaces. TheGTAM was trimmed to closelyapproximate adjacent teethon the mesial or distal of theextraction site and to cover theinterproximal bony crest (Fig 3).The epithelium was removedtrom the marginal 2 mm ot thepalatai flap to expose connec-tive tissue. The faciol flap wasundermined and advanced togain primory closure over theGTAM and underlying impiant(Fig 4). Vertical incisions wereused to permit the faciai flap tobe mobilized adequately toobtain primary closure.

A postsurgical radiographs taken to document the

•elationship of the impiant tohe bony socket (Fig 5). The

Fig I At the initial surgery, the implant wos ploced in the socket with the lap ot theimplant level with the crestat bone ond the end ot the implant extending post theapex ot the socket.

ASC

CSC

Origtridl socket apex

C' I ABS

Top of implont

Fig 2 These clinical measurements were mode immedioteiy öfter imptant piace-ment. prior to tlap closure, and at the second stoge surgery offer ó months of heat-ing, Additionolly, the horizontoi distance from the sacket wall to the imptont wasmeosured on the M, D, F, ond L surfoces. ABS - from the top at the implont to themost apical base of the residual socket affer implant plocement ASC = From thetop of the Implant to the most apicol socket orest. CSC = From fhe fop of theimpiant to the most coronoi socket crest.

Volume 14. Number 4, 1994

336

Fig 3 The GTAM was trimmed andplaced to cover the dentol implantand surrounding bane.

Fig 4 The tocial flap was advancedand sutured to provide primary closureover the implant and GTAM.

Fig 5 Radiograph of impiont immedi-ately after its placement in the socketduring the first-stoge surgery. A radioiu-cent space is apparent between theimpiont and the soci<et in the corona!one third.

Fig 7 flop eievotion ot the 0-monthreentry exposed the GTAM.

Fig 8 The GTAM was removed toexpase the impiant. Crestoi Ponegrowth was evident over the tap of theimpiont on the distoi.

Fig 6 Radiograph at the time af the Ó-month reentry showing evidence ofbone fiil around the coronal ane-thirdof the impiant.

The International Journal of Periodontics & Restorative Dentisfry

337

Fig 9 Osîectomy was performed toexpose fhe top of the implant

Fig 10 The flap was positioned OTOundtop of implant and fhe healing screwplaced.

Fig 1} Restoration of the implant wifha fuii crown was completed after initialsoft tissue healing.

patient was prescribed amoxi-ciliin, 500 mg three times a dayfor 10 days and 800 mg otibuproten as needed for pain.Chiorhexidine mouthwash(Procter & Gambie) was pre-scribed for use postsurgicaiiy.

One week after impiantpiacement, the sutures wereremoved, the surgical site wasevaiuated, and a dentai pro-phyiaxis was performed, Thepatients were seen weekiy forthe next 3 weeks for prophy-iaxis, crai hygiene instruction,and continued evaiuation ofthe heaiing surgical site, Duringthis postsurgicai period, a tem-porary prosthesis was providedfor esthetic purposes, Fivepatients received resin-retained fixed partioi dentures,The remaining patients, whoseimpionts were piaced in poste-rior edentulous areas, receivedeither a provisional removabiepartial denture cr no prosthesis.To enhance csseointegraticn,all prostheses were reiieved toensure that the impiant re-

mained out cf function. Pa-tients were seen monthly forthe next 5 months to continueposfsurgical care.

Six months after piacementcf the impiant, a second-stagesurgical procedure was per-formed tc expose fhe implant.A periapicai radiograph wastaken to document healing(Fig 6). Under iocal anesthesia,mucoperiosteal flaps were ele-vafed (Fig 7) and the GTAMand underlying soft tissue wasremoved to expose the implantond surrounding bcne (Fig 8).Ciinicai measurements wererepeoted tc document bonefiii or remodeling at the prede-termined sites around the den-tal implant. Osteotomy wosperformed, if necessory, tcestablish normal bcne contoursand permit repositioning of thefiap around fhe tcp of theimplant (Fig 9). If residuai bonydefects were presenf aroundfhe impiant they were graftedwith demineralized freeze-driedbone ailograft of this time. The

implant procedure wos consid-ered successful if ossecintegra-fion was attained. Mobiiity ofthe impiant signified lock ofosseointegration of fhe fixtureand failure of the procedure. Ifosseointegration had not oc-curred, the impiant was to beremoved and the resultantsocket debrided and permit-ted to heal secondarily. Thefiaps were repositioned andsutured, closely adopting tothe successfully integratedimpionts. A heaiing screw wasplaced (Fig 10) and the patientwas referred for restoration (Fig11),

After fabrication of the per-monent prostheses, the pa-tients were scheduled toreceive a denfai prcphyiaxisevery 3 months for the nextyear to maximize tissue healthand ÎO permit continued evalu-ation of the implants. After 1year, patients were instructedto ccntinue wifh their routinedental recall.

Volume 14, Number 4, 1994

338

Results

Descriptive statistics were usedto characterize the results ofheaiihg after the implant-GTiiprocedure. Osseointegration ofthe impiants was reported assuccess or failure. Differencesbetween groups were ona-lyzed using the Mann-Whitneytest for nonparametrio data.Eleven implants were plaoed in10 patients, who ranged in agefrom 27 to 81 years (mean of51.2 yeors). Nine of theimpiants were placed in themaxilla Ohd two in the man-dible. All extracted teeth werediagnosed as hopeiess andwere extraoted with minimaitrauma to the remaining bone.The oauses of tooth failure,whioh inciuded vertical rootfractures, adult periodontitis,and endodontic failure, oisoled to the formation ot isoiotedbony defects, such as facialdehiscences and uneven mor-ginai ridge confours. Thesedefeots compromised the con-tinuity of the bony ridge ondblood suppiy around theimplants, oftecting the overoliprognosis for bone fiii.

All implants were plaoed inimmediate postextraotionsockets. Implant length waschosen so that, when the top

of the implant was p lacedlevel with the most coronalcrest ot the alveolar bone, theend of fhe impiant extended 2to 4 mm apioai to the looationof the originai root apex. Thepiacement of the impiant,extending past the apex of thesccket, as well as the taper ofthe socket resulted in at leasthalf af the implant being indirect contact with the pre-pared bone. All implants werestable at the time of place-ment.

Although primary closureover the implant and GTAMwas obtained in all cases, dur-ing the first 2 weeks of the post-surgical healing period, thematerial became exposed in 6of the 11 sites. This exposedmaterial was retained in posi-tion for ó weeks to 4 months;the patient was prescribedchiorhexidine mouthwash.When the GTAM material wasremoved eoriier than thescheduled ó-month interval.the implants and tissues aroundthe implants were not dis-turbed, and the fiap used forGTAM removai was reposi-tioned to caver the impiantand surrounding tissues. Thesesites were then reopened at ómonths in accordance with thestudy protocol, and oli soft tis-

Ttie Internatianal Jaurnal ot Periadontics 8; Restorative Dentistry

339

sues were removed to uncoverthe implant and surroundingbone. This permitted direct visu-alizotion ond meosurement ofthe bone around fhe impiant.In tive sites the GTAM remoinedcovered by the soft tissue; at 6months these impiants weresurgicoiiy exposed ond meo-surements were taken.

Meosuremenfs at the time otimpiant piacement

At the level ot the alveolarcrest, the horizontai distoncetrom the bony socket waii tothe implant overaged 1.4 mmon the mesial surtace. 0,7 mmon the distal surface, 1.4 mm onthe faciai surface, ond 2.1 mmon fhe ilnguol surface. Thisbone-to-impiont gap varieddue to impionf placement ondthe irreguior shope of the sock-ets. The widest defects weregenerally on the facial and lin-guoi surfaces due to thegreater faciai-to-iinguoi dimen-sion ot most roots, in aii cases,the remaining aiveolar bone, inconjunction with the shape ofthe socket, provided odequafesupport to hoid the GTAMmaterioi away from fhe implant,providing a space tor bone fiii.

The verticoi distance fromthe top of the implant to thecrest ot the bony socket voriedat ditterent iocotions aroundthe implant. This voriation wasdue to the more caronoi ioco-tion of bone at the interproxi-mai sites and to the differencesin bone ioss associafed withthe individual extracted tooth.The vertical distance from thetop of the impiant to the mostcoronal socket crest (CSC) was0.2 -f 0.0 mm. The distance tromthe top of the implont to themost apical socket orest (ASC)was 4,4 + 2.1 mm. The most api-col crest of the socket woslocoted toward the fooiai sur-toce at 10 ot the impiant sitesond toword the paiatal surtoceot one site. Two extraction siteshad focial dehiscences of 8.0mm and 8.5 mm at the time ofimpiant placement. Thesedehisoences were associatedwith the verticai root fracturesthot led to the extraction of theinvolved teeth. The distancefrom the top of the impiont tothe ASC ronged from 2 to 5mm at the remaining sites. Themean distance from the top ofthe implonts to the apicol baseof the residuol socket (ABS) wos9.2 + 2,0 mm and ranged from6.0 mm to 12.0mm,

Volume 14, Number 4, 1994

340

Fig 12 Distribution of CSC meosure-ments. Mean tor all sites equaled -0.9 ±1.7 rnm. • = The ihdividuoi measute-mehts for eoch imploht at this location.< 4 mos = Sites where GTAtA becomeexposed ih the first 2 weei<s affer inser-tion, requiring removol of the GTAt\A6weeks to 4 months affer plocement. ómos = Sites where GTAtvJ remained inplace until the 6-mohth reentry NSD =No significaht difference. & = Meon torali measurements in this group,

[mm

)ur

emen

tÖ

EQOD

3n

ge

i

.cÜ

2,0—

0 . 0 ^

-2 .0—

-4 ,0—

All sifes

•

•A «A

A

Anterior Posterior < 4 mos 6 mosArch position GTAM removol

Six-month heaiing results

All impionts were osseointe-groted at the ó-month reentry.The sott tissues around the siximplants exposed by earlyremoval ot the barrier mem-brone appeored healthy ondwell odapted ot the time ofthe second-stage surgery.

Crestai résorption led to amean loss ot 0.9 + 1.7 mm ofbone meosured from the CSCfo fhe top of the implant (Fig12). Crestal résorption ot 0.1 +3,5 mm was noted at the ASC(Fig 13). Bone fili measured atthe site ot the ABS averaged3.ó + 2.ó mm (Fig 14). Two siteswith large preexisting taciaidehlscences showed addition-al crestai résorption at the siteot the originoi dehiscence.These sites, the only ones that

did not demonstrate boneregeneration from the base ofthe sooket, skewed the dotafrom the remaining sites: whenmeasurements tor these twoareas of fenestration are elimi-nated from the calculations,bone remodeling at thé ASCchonged from a ioss of 0.1 mmto crestai apposition of 1.1 mm,and bone fill at the sifes of theABS increased from 3.ó mm to4,4 mm,

Norrower defects tendedto fill completeiy with bone,whereas the wider detectstended to heal with partialregeneration ot bone. After ómonths of healing, residualdefects were located in theareas ot the initially deep, wideosseous defeots (Fig 15a to15g) and oreas of preexistingfooioi dehiscences.

Ttie I nternotionol Journal of Periodontics & Restorative Dentistry

ure

ment

(mm

)m

eo

snbone

Ö !

.C

U

5.0—

0.0—

5.0—

10.0—

•

•

•

All sites

• • • •

A A

: • : •

•

Anterior Posterior < 4 mos 6 mosArch position GTAM removol

Fig 13 Distribution af ASC measure-ments. Mean for oil sites was -0.1 + 3.5mm. • = 7>ie individual measurementsfor each imptant ot this tocation. < âmos = Sites where GTAM becameexposed in the first 2 weet<s after inser-tion, requiring removal of the GTAtvl 6weet<s to 4 mantt^s after ptocement. 6mos = Sites where GTAM remained inbtoce until the 6-month reentry. A =Meon foe oil measurements tn thisgroup.

(mm

)B

one

fil

9.0—

6.0—

3.0—

0.0—

•

A

. .

Ad sites

•

•A •

A

. .

Anterior PosteriorArch position

•

A

• A

. .

1

< 4 mos ó mosGTAM removol

Fig M Distribution of ABS measure-ments Meon for all sites wos 3.6-I-2.6mm The individuot measurements foreach imptant ot this tocation. < 4 Ma =Sites where GJAM became exposed inthe first 2 weeks after insertion, requir-ing removol of the GJAtvi 6 weei<s to 4months after placement. 6 tv^a - Siteswhere GtAM remained in plooe untitthe ó-month reentry A = Meon for atimeasurements in this graup.

Volume 14, Number 4.1994

342

Fig ISa Radiograph of ttie remoininghemisectianed root, which wos honre-storable due to mesiol root coiies thotextended apicatly within the periodan-tol osseous detect.

Fig iSb At the time of inipioni uiO'.e-ment bone loss due to periodontitisond the shape of fhe extraction socketcombined to torm o ciroumferenfiolosseous defect thot measured 9 mmfrom fhe top of fhe implant fo fhe baseof the defBcf on the facial surface ofthe implant.

Fig lSc This lodiograph. taken imme-diately öfter surgical placement of theimplant shows extension af the implonfpost fhe apex of fhe sacket and thelack of cantact between implont ondbane in the caranal area of the socket.

Fig I5ct Afthe time of fhe secondstoge surgery, removal at all son tissueoround the implanf revealed 5 mm ofbone fill from the base af the detect 2mm of crestalresarptian, ando resid-ual 2 mm oircumferential defectaround the impiant.

Fig I5e The residual defect was graft-ed with demineralized freeze-driedbone ollogroft at the time af the sec-and stage surgery ond the sott tissuewos readapted oiound the coronolport af the implont

Fig ]5I Radiagroph token I year offerfhe stoge-two surgery indicóles crestalbone résorption and apporenf bane nitoround the implant that extends coro-nal to the implont threads

Fig lSg Atthe I-yeorréévaluation,fhe patient wos camfortable and fheimplont functianed normally There wosno apparent gingivol infiommofion,ond the implant wos not mobile.

The International Journal ot Periodontics a Restorative Dentistry

343

Early removal of GTAM

The sites where the GTAMbecame exposed andrequired early removal had 2.0± 2.1 mm cf bone fill of fhesockef (n = ó); af the five siteswhere the membrane re-mained in piace and undis-furbed for 6 months, the bonefill was 5.5 ± 1.7 mm (see Fig14). Grestai bone lost at theASC was also associated withearly removai ot the GTAM(see Fig 13): sites with earlyremoval of GTAM lost a meanof 2.4 mm of cresta! bone afthe ASG location, whiie thosesites that retained the GTAM foró monfhs gained a mean of 2.6mm of cresta! bone at ASC (P <,01) (see Fig 13). No signiticantdifference was tcund at theCSC iooations (see Fig 12).Bone fiii at fhe ABS was signiti-cantiy greater (P < .05) at thosesites where the GTAM wasretained for 6 months (see Fig12). The early ioss cf the GTAMalso corresponded with thetwo sites that hod preexistingfaoiai dehiscences that dem-onstrated no bone regenera-tion at the dehiscence sites.

Anterior versus posterior sites

The six anterior sites in this studywere iocated in the maxiiia;the posterior sites were In themaxiiia (three sites) and in themandible (two sites). The ante-rior sites demonstrated bone

apposition at all measurementlocations. Posterior sites dis-played significantly less bone fill(1.6 + 2.1 mm: P < ,05) at theABS (see Fig 14) than did theanterior sites (5.3 + 1.6 mm);they aiso had signiticantlygreater crestal bcne loss at theASC (P < ,05) and the CSC (P <.05) (see Figs 12 and 13). Allposterior sites required earlyremoval of the GTAM. whiieoniy one anterior site requiredeariy removai of the GTAM,

Discussion

The main purpose of thisresearoh was to evaluate thesuccess of osseointegration ofa titanium plasma-sprayedimpiant when piaoed in anextraotian site immediotelyafter extraotion of the naturaltooth. Clinically, all 11 impiantswere successfuily osseointe-grated at the 6-month seoond-stage surgery. Although somevariation was evident, evalua-tion of bone heaiing fo deter-mine patterns of remodeiing inreiotion to the preexisting bonyanatomy showed compiete tillof most of the sockets. In gen-eral, résorption at the CSC andapposition at the ASC had atendency to level the alveolarcrest around the implants.Heaiing cf bony defecfs thatremained after the impiantswere placed resembled heol-ing seen arcund periodontaliyinvolved teeth with verticol

defects. Introbony defectsfilled from the apicai areas.Narrow defecfs fiiied oom-pietely. As the socket becamewider ooronaliy, bane fiii wasless likeiy to be compiete.Areas of thin bone, most fre-quently on the faciai surface,provided the ieost regenera-tion; interproximal areas hadthe most predictable bone fiii.

iHealing patterns appearedto be reiated to the blood sup-piy and the thickness ot thebone remaining after extrao-tion. Interproximai areas withintact moderately thick boneand an intact periodcntai liga-ment on the adjacent teethwere less subject fo traumaduring extraction than facialand paiatai bone. Additionaily,the paiatai bony plate wasusually thicker than the facialpiafe, and in most oases, thepaiatai fiap was elevated onlyminimally to gain access forplacement cf the GTAM. Thethickness of the palatal boneand the minimal flap reflectionmay have helped preserve fheblood supply in this area.

Facial bone was either thinor had a dehiscenoe that wasassaciated with the originalcause of tooth failure (ie. verti-cal root tracture. endodontictaiiure, or aduit periodontitis).This bone was more subject totrauma and ioss of blood sup-piy during toofh extroction.Faciai tiap eievation wasextensive due to the need toadvance the fiap coronaliy to

Voiume 14, Number 4. 1994

344

fig 16a Implants placeo iri the sockets of teeth 11 and 21during the tirst-stoge surgery were stoble but hod residual cir-cumferential intraosseous defects. These defects were pre-sent due to the diameter ot the coronol areo of the socketwhich was wider than the implants.

Fig 16b At the 0-month reentry, bone remodeling wosnoted. Bone till ot the soci<et combined with faciol bonerésorption resuited in a thin layer of faoial bone thot was inti-mately adapted to the implant.

cover fhe implont ond GTAM.Addifionaiiy. bone résorptionafter extroction of teeth is gen-eraily greatest from the facialospect." This tended to norrowfhe maxillary aiveolor ridgeand compromise bony healingon the faciai surfoce of theimplant. Figures loo and lobdemonstrate a situation wherethe initioi spoce between thecoronai hoif of the implont ondthe socket wail fiiied with boneond achieved clinicaiiy appar-ent osseoinfegration, whilefacial rescrptlan ied to thinningof the focial bone and partialthread exposure. The combina-tion of preexisting facial dehis-

cences, fhin facial bone,extroction trouma. naturailyoccurring résorption from fhefociol surfoce, ond exfensiveflap eievation resulted in signifi-cantiy poorer bone regenera-tion on the faciai surface.

Impianf placement wosplonned to provide ideol posi-tioning for prosthodontic res-toration. Usually, this meantthat the impiont was placed inthe center of the socket, asequidistont from oii four socketwails as possible. iHealing pot-terns seen in this study indicatethat it would be more effectiveto pioce the implant towardthe paiatai side of the socket.

The thicker paiatai bone wasless iikely to heal with a residualdehiscence, thus providing amore reliobie oreo of bone forstobiiizotion of the impiant.Moving the impiant toward thepalatal side olso would narrowthe gap between the implantand bone on three sides. Thiswould result in a greater dis-fonce from fhe facial bone tothe impiant and an improvedblood supply on the mesial anddistoi walis of the residuoidefect for ingrowth ot bone.This does, however, enlorgethedefect on the focial side,which may require an osseousgraft tc optimize heoling.

Ttie Internotionol Jaurnol ot Periadontics & rîestorative Dentistry

345

The implant in this studywas used in an unconventionolmanner when compared tothe manutacturer's protoooi.The m implant is designed as aone-stage implant. At the timeof surgical placement, thepiasma-sprayed portion ot theimplont body is placed in aprepared bone site, with thesmooth collar extendingthrough the alveolar mucosa.Intimate contact of the implantwith the bone, when piacedideolly in an edentulous ridge,resuits in predictable osseointe-gration. Plooement of theimplonf in an extraction sooketdid not permit intimate contactwith the bone; therefore, fheuse of a barrier membrane toprevent ingrowth ot epitheliumand conneotive tissue ceilsfrom fhe mucosa was reaulred.The implanf wos olso placed sofhat its top was level with theCSC. This placed the polishedcoiiar of fhe implanf within fhesooket.

There was some concernthat bone may not osseointe-grate with a poiished titaniumsurtaoe and that placement otthis impiant in the manner usedin this study may have affectedbone regeneration, in toct.crestal bone résorption andpartial fill of the residuol socketsdid resuit odjacent to the pol-ished collar of fhe implanf insevero! oases in this sfudy. in afew instances, however, osmaii area of the piasma sprayremained exposed. These

areas were debflded andgrofted with demineralizedfreeze-dried bone allograft dur-ing the second-stage surgery.Less commonly, bone regener-otion extended to the top ofthe implant, requiring an osteo-tomy to permif proper place-ment ot the sott tissue floparound the implant collar endlevel with the top of theimplant. Regeneration ot bonearound the impiant appearedmore dependent on bioodsupply, the width of theosseous defect, and the pres-ence of a bany dehiscencethon on fhe presence of thepoiished titanium surface.

All teeth in this study wereextrooted because of exisfingpathology and. thus, did notprovide ideal sites for ploce-ment of the impianf. Teethwere extracted due to tailedendodontic therapy, root troc-tures, root caries, or periodonti-tis resuiting in severe attooh-ment loss; therefore, theresidual sookets were consid-ered oontaminated by micro-organisms due to the ossooia-tion with o foiiing foofh. This isunlike fhe preparation ot o sitefor piacement of an impiant ina healed ridge where contami-notion by microergonismswould be iimited. The extent towhich the presence of microor-ganisms affected heoiing ateach impiant site is unknown.but it could account for someof the variabiiity of boneregenerofion around the

impiant fixtures. Althoughontibiotics were prescribed forthe potients to minimize theetfect of bacteria in the surgi-cai area, they could not beexpected to be totaliy effec-tive.

in areos with preexistingtaoiai dehiscences, the aiveo-lor bone mesial ond distal tothe dehiscence was adequateto support the GTAM os it wastented over the impiant. This.combined with the wide feciai-to-iinguai dimension of thesookets and the placement ofthe impiant in the center ot thesocket, resulted in a spacebeing maintained between themembrane and implant to per-mit bone fill. Thus, lock of bonefill in this area could nof beottributed to coiiapse ot theGTAM agoinst the implont. Infact, a thick ioyer of dense col-iogenous oonnecfive tissuewos usually found filling thisspaoe. This led the au'thors toconclude thot grafting wifh onosteogenio material, in addi-tion to the use of GTAM, moybe needed to provide eddi-tionel regenerotive stimuius inareos ot lorge residuoi osseousdefects.

Volume 14. Number d. 1994

34Ó

Conclusion and sunnmary

Eleven implants placed in toothsockets immediateiy followingextraction were all found to beosseointegrated at tine ó-montin second-stage surgery.ivlost ot the residual soci<ettilled compieteiy, ciinicaiiy pro-viding intimate contact of sup-porting bone with the dentalimplant. Crestai bone resarp-tion was noted in the area otthe most coronai socket crest,vi/hereas crestai apposition wasnoted in areas of the most api-cai soci<et crest, which tendedto ievei the soci<et around theimplant. Posterior sites andareas with thin bone and facialdehiscences demonstrated theleast bone regeneration, whileanterior sites and palatal andinterproximai areas providedthe most consistent boneregeneration. The use of GTRtechnique resuited in completetiil of bone around the dentaiimpiont when defects werenarrow. However, the GTRtechnique did not aiways resuitin compiete bone fiii in thoseareas that were compromisedinitially.

The toiiovying recommen-dations concerning impiantplacement in sockets immedi-ateiy after tooth extractionmay heip aptimize boneregeneration and enhanceosseointegration:

1. Teeth shouid be extract-ed as atraumoticaiiy as possibieto preserve crestoi bone heightand protect the local bloodsupply,

2. The impiant should bepiaced toward areas ot thickbone and away from thin boneor bony dehiscenoes. in gêner-ai, this requires piacement ofthe impiant toward the palataisurface.

3. Grafting with anosteogenic materiai shouid beconsidered when iorge osseousdefects remain after impiantpiacement. Facial dehis-cences, which exhibited theieast osseous regenerativepotentiol in this study, may gainthe greotest benefit trom thepiacement of a grafting mote-riai.

A. When the iTi implant ispiaced in an extraction socket,the top of the implant shouidbe approximately ievel with thecrestai bone. This wiii aiiow torcrestai resorptioh and helpmaintain the piasma sprayedportion of the impiant in a sub-crestai iocation after heaiing.

5. Keeping the GTAM sub-merged and unexposed isimportant in obtoining optimairesuits; theretore, the surgicaitechnique shouid be designedto gain primary ciosure. TheGTAM should be trimmedappraximateiy 1 to 2 mm shortof the adjacent teeth to permitreattachment of the soft tissuetiop to heip minimize eariymembrane exposure.

Ó. The surgicai techniqueused in this project led toexcessive soft tissue manipula-tion and compromised estheticresuits. The authors recom-mend that implant piacementbe deioyed for ó to 8 weei<safter tooth extraction to permitregeneration of soft tissue averthe healing socket. This simpii-fies the surgicoi procedure andcan enhance esthetics by mini-mizing tiap displacement andthe need tor vertlcai incisions.This deiay may aiso minimizethe effect of microorgariisms,associoted with the failedtooth, on wound heaiingaround the tooth impiant.

The International Journal of Periodontics & Restorative Dentistry

Acknowledgments

This project (Naval Medical Researchand Development Command study 39-Oó-I0d8-O0) was reviewed bv theCommittee for the Proteotion ofHuman Subjects and the ScientificReview Committee. It was funded bythe Noval Health Sciences Educationand Troining Command (Code 0402),Bethesdo. Maryland 20389-5022,

References

1. Sullivan D. A solution for the pros-thetic problem of the hemidentofearch-iissue integrated prosthesis, IntJ Penodonf iïesf Denf 1986;ó(4),67-Sl.

2.Adell R, Lekhalm U, rioci<lef B,Branemark P-l. A 15-year sfudy ofosseointegrated implants in thetreatment of fhe edentulous jaw. IntJ Oral Maxillofao Surg 1981;10'387-416.

3. Adeil R. Clinical results of osseointe-grated implants supporting fixedprostheses in edentulous jaws JProsthet Denf 1983:50:251-270

4. Kinni M, Hpkcma N. Caputo AA,Faroe transfer by osseointegrationimplant devices. Int J OralMaxiilofac Implants 1987:2:11-14,

5. Brânemark P-l, Osseointegration andits experimental bacitground JPrasthetDent 1984:50:199-210

6 Schnitman P, Shuiman L Recom-mendations of the consensus devel-opment conference on dentalimplants, J Am Dent Assoc 1979:98:373-377.

7. Holt R, Dental implants, J West SocPeriodont Abstr, 1986:34.49-55.

8,Tatu O, Lebowitz M. Anatomic con-siderations for dental implants, JOral Implantol 7991:17:16-21.

9- Mecali IÍA, Rosenfeld AL. The influ-ence of residual ridge résorptionpatterns on implant fixture place-ment and tooth position. Port i, int JPeriodont Rest Dent l991:H(l):9-23.

10. Shuiman L6, Surgical considerationsin implant dentistry, J Dent Educ1989:52:712-720,

11. Worthington P, Bolender CL TaylorTD, The Swedish system of osseoinfe-grated implonts: Problems andcomplicotions encountered duringa 4-yeQr trial period, Int J OralMaxillofoc Implants 1987:2:77-84,

12. Dahlin C, Generation ot new boneoround titanium implants using amembrane technique. An experi-mental study in rabbits, Int J OralMaxiilofac Implants ¡989,4:19-25,

13. Wachtel H, Langford A, BernimoulinJ, Reichart P, Guided bcne regen-eration next to osseointegratedimplants in humans, Int j OralMaxillofoc Implanfs 1991 ,"6:127-135,

14. Dahlin C, Lindhe A, Gotflow JHealing of bone defects by guidedtissue regeneration Plast ReconsfrSurg 1988:81:672-670.

15. Becker W, Beoker BE, Guided tissueregeneration for implants placedinto extraction sockets ond forimplant dehiscences: Surgical tech-niques and case reports. Int JPefiodont Rest Dent 1990:10(5);377-391,

IÓ. Lazara RJ. Immediate implantplacement in new spots advon-tages, Int J Periodont Rest Dent1990:9(5):333-343.

17, Nyman S, Lang N, Buser D, BroggerU. Bone regeneration odjocent tctitanium dental implants using guid-ed tissue regeneration: A report oftwo cases, Int J Orol MaxiilofacImplants 1990,5:9-14.

Volume 14, Number 4, 1994