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359

Piezoelectric Surgery in Implantology:A Case Report—A New PiezoelectricRidge Expansion Technique

Tomaso Vercellotti, MD, DOS'

The purpose ol this preliminary article is to presenta new surgical technique that,

than/cs to the use oimodulated-frequency piezoeiectric energy scalpels, permits

the expansion o>the ridge and the placement o!irnplants in single-stage surgery

iri positions that were not previously possible with any other method. The tech-

nique involves the separation of the vestibular osseous Hap irom the palatal flap

and the immediate positioning of the implant between the 2 cortical walls. The

case report illustrates the ridge expansion and positioning of implants step by

step in bone of quality I to 2 with only 2 to 3 mm of thickness that is maintained

for its entire height. To obtain rapid healing, the expansion space that was creat-

ed for the position/ng of the implant was filied, following the concepts of tissue

engirreering, with bioactiue glass synthetic bone graft material as an osteocon-

ductive factor and autogenous p/ate/et-rrch plasma as an osteoinductive factor.

The site was covered with a platelet-nch plasma membrar^e. A careful evaluation

of the site when reopened after 3 months revealed that the ridge was mineralized

and stabilized at a thickness of 5 mm and the implants were osseointegrated. (Int

J Periodontics Restorative Dent 200Û;20:3 59-365,)

'Pnvate Practice, Genova and Merano, Italy,

Reprint requests: Dr Tomaso Vercellotti, Via Xil Ottobre 2/111, 16121Genova, Italy,

The presence of a thin edentulousridge in the maxilla represents a clin-ical situation in which the positioningof endosseous implants can be com-plex, and at times impossible, in asingle surgical operation. In fact, theminimum thickness of the implantsite for the standard method, that is,with preparation of the implant siteusing burs, is at least 6 mm to permitthe positioning of a 3,75-mm implantand the maintenance of a buccal andpalatal wall of at least 1 mm, '^

When the thickness of the ridgeIS reduced to about 4 mm in themost coronal position and the vol-ume increases in the apical direc-tion, preparation of the implant sitewith burs produces a dehiscencethat is generally vestibular and leadsto the exposure of several millime-ters of the thread of the implant. Thisdehiscence has to be considered adefect to be treated with additionaltherapy,^-^ such as bone graftingand/or guided bone regeneration.This factor reduces the predictabilityof the treatment because of eventualmembrane collapse, exposure, andinfection, with incomplete reforma-tion of the bone,^ When atrophy is

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. .ind the ridge is..J it does not pre-

sent an apical expansion, the stan-dard method with burs must beabandoned because its use willbring about the complete destruc-tion of the residual crestal bone.

As sufficient bone volume is thefundamental prerequisite for osseo-integration, some authors'""'^ main-tain that the positioning of the im-plant must be preceded by a bonegraft that, once established and min-eralized, offers sufficient volume forthe standard method. These bone-grafting methods, which are not with-out risk of complications during thehealing period, necessitate 2 surgicaloperations. This doubles the timenecessary to finalize the implants.

Some authors'^'^ prefer to useridge expansion techniques withimmediate positioning of the im-plants to avoid unwanted dehis-cence or fenestration that necessi-tates additional therapy. Osteotomy,as described by Summers,'''"'* pro-duces immediate expansion of thesingle implant site by the insertion ofosteotomes of increasing dimensionand permits positioning of theimplant in thin ridgesof 3 to 4 mm inthickness. This is a less traumaticmethod that does not remove bonefrom the implant site but dislocatesit, increasing the volume without pro-voking any defect that will necessi-tate additional therapy. Even thebone flap technique" permits posi-tioning of the implants at the sametime as the expansion, which consistsof distancing the vestibular crestalwall from the palatal wall with theformation of an ample defect with

morphologic characteristics that areextremely favorable to bone heal-ing. In fact, the tissue repair is pro-tected from microtrsumas by thepresence of the vestibular and palatalcortical walls and is comparable to afracture rima characterized by a validvascular supply and a rich osteoin-ductive cellularity, which comes fromthe diversion of the meduila.

Both of these expansion tech-niques make use of the elasticity ofthe bone ridge and are recom-mended in the presence of tenderquality bone (Types 3 to 4], but theyhave mechanical limits when theresidual bone is extremely mineral-ized because the mechanical expan-sion maneuvers can produce uncon-trolled fractures. When inelasticcortical walls are separated, theeventual fracture of one of the wallsproduces the total detachment ofthe vestibular cortical bone and theconsequent interruption of the vas-cularization process, provoking bonedeath and the loss of the implants.

It is the author's opinion that thetraditional mechanical expansionmethods cannot be used with pre-dictable outcome in the presence ofa very mineralized bone ridge asis often seen in a long-standingedentulous zone. The basis of thenew piezoelectric ridge expansiontechnique is the use of variable-frequency piezoelectric energy as apowerful and efficacious surgicalforce that is able to cut bone withoutuncontrollable traumas. This permitsthe expansion of the edentulousridge no matter what the quality ofthe bone, even in the case of themost mineralized.

This new method, which is pre-sented here as a case report, permitsthe surgeon to obtain the expansionof a very mineralized bone ridge{quality 1) of 2 to 3 mm in thicknessat the same time as the positioningof the implants, intervening where ithas been impossible with other tech-niques. The fundamental idea onwhich piezoelectric surgery is basedis the use of a surgical force that isableto cut bone according to the re-quirements of the case, with a pow-erful and precise energy and withoutexcessive traumas or the risk of frac-turing the ridge.

Method and materials

The patient was a man of 55 yearsof age. His medical history indi-cated arterial hypertension that wasunder medical treatment. His den-tal history included precocious lossof the left lateral incisor, canine,first and second premolars, andmolar about 20 years previously.During the clinical examination, aridge defect with reduction in thethickness of the bone, which ap-peared to be thin, was diagnosed.A computed tomographic {CT}scan demonstrated adequate ridgeheight, and the paraxial lines of theimplant sites showed a thicknessof less than 3 mm for the entiredevelopment of the apical crown.The bone quality was Type 1 to 2,and the cancellous residue onlyappeared as a line of minor radi-olucency separating the vestibularcortical bone from the palatal bone(Figi ] .

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Fig 1 (left) CT image permits the mea-surement of the tliiclfness of the boneridge, which is 2 to 3 mm and develops toa height of 15 mm. The bone appears tobe veiy mineralized, ol quality Î to 2, andthe cancellous bone appears as a lirie olmjnor radioiucency separating the vestibu-lar cortical bone from ihe pa/ata/ bone

Fig 2 (above) Fdentufous ridge at ihebeginning of surgery. The thickness, mea-sured with B periodontal probe, variesIrom 2.2 to 2.8 mm.

Fig 3 Edentulous ridge after a minorosteoplasty to level the surface. The lisp isof miied ihictness to maintain the integri-ty of the periosteum on the vestibular andpalatal mails.

Fig 4 Lateral view m which the mixed-thickness flap and periosteum that coversthe vestibular cortical wall are both visible.The VI piezoeiectric scalpel is in use.

Fig 5 Horizontal bone rncision is per-formed in the middle of the ndge wfth 2releasing incisions, one mesial and onedistal.

Fig 6 Ridge alter the use of piezoelectricscalpel V2 the vestibular cortical wall hasbeen separated from the palatal wall fol-lowing the bone flap technique.

The patient was treated with alocal anesthetic (Septanest withadrenaline 1:200,000, SpecialitiesSeptodont). Antibiotic therapy of 3 gof amoxicillin (Zimox, Pharmacia &Upjohn) 1 hour before intervention,1.5 g that night, and 1 g twice a dayfor5 days was prescribed. The post-operative pain was controlled with100mgofnirnesulide(Aulin, Helsinn

Healthcare] twice a day for the firstand second days. For clinical plaquecontrol, the patient was instructedto rinse his mouth for 1 minute twicea day with chlorhexidine 0.1% for 2weeks, peri orm mechanical plaquecontrol in the remaining naturalteeth, and rinsewith a saline solutiontwice a day for another 2 weeks.

Surgical technique

A mid-crestai incision was extendedbuccally and palatally into the sulcusto the mesial and distal sides,respectively, of the adjacent teeth,where divergent releasing incisionswere extended into the vestibule. Amucoperiosteal flap of the totalthickness of the summit of the bone

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Fig 7 Implant sites híi'e been c<£;í:edwith a 2-nim twist drill fol/owrng the use ofp/eioeiectfic osteotome V3.

Fig S I'.eiv of the expanded ridge afterIhe positioning of ihe implants.

Fig 9 Lateral view after positioning ofthe impianfs- fhe integrity olti^e vestibularcortical watt without deliiscence or fenes-trdtion can be observed.

Fig 10 VfewoflJiendge with theimplants, which maintain their separatebone flaps. Piezoefertric scalpel MI cre-ates mrcraopenings on the 'Jestibuhr andpaiata' waifs to stimii/ate bleeding on theinside of the surgicat wound.

Fig 11 Get formed of bjoactive glass syn-thefjc bone graff material and autogenousFRP obtained from ti 5D-mL venous bloodsample 30 minutes before the surgery.

Fig 12 (mpíanís are in position and thesutgicat wound is fi"ed with the bone graftmateria) and PRP.

ridge was lifted and then continuedwith a flap of partial thickness in thevestibular fornix. This flap permittedthe denuding of the summit of theridge while maintaining the perios-teum on the vertical walls and per-mitting the creation of an extremelymobile mucous flap that permittedsuturing without any tension afterthe expansion. Using a periodontalprobe, various measurements weremade of the ridge, which had a thick-ness of from 2.2 to 2.8 mm {to beverified after projecting the image)

{Fig 2). Thetopofthe ridge was lev-eled with a diamond bur to obtain auniform surface of 2.5 mm in thick-ness (Fig 3). A horizontal incision wasthen made in the middle of the ridgewith the first piezoelectric scalpel,VI {Mectron Piezo Surgery Device],and 2 releasing incisions were madeto a depth of 5 mm in the vestibularbone (Figs 4 and 5). Another 2scalpels of greater length and thick-ness were successively inserted api-cally to obtain a mobile vestibularflap (Fig 6).

The implant site was preparedwith a 2-mm twist drill and a piezo-electric osteotome of 3 mm, aboveall on the palatal side {Fig 7], toobtain an apical implant alveolusthat guaranteed the primary stabilityof the 2 implants; this would ensurethat, once inserted, the implantswould not undergo dehiscence orfenestration, but maintain their sep-arate bone surfaces {Figs 8 and 9).Microopenings were appositely cre-ated in the vestibular and palatalbone flap with an Ml insert to

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Fig 13 Ridge is covered with a PRP mem-brane to protecl and stabilize the graft.

Fig 14 Fiaps are sutured on 2 sides withhorizontai matfress stilciies on the perios-teum; normal stitches are used on theUpper surfe ce.

Fig 15 Viewoftfiendgeafterimontiis.at reopening: it is posslbie to see theheads of tfie implants through the pa'ata'mucosa. The implants are m a vestibularposition without Iferatjnöec/ tissue.

Fig 16 (left) View after reopening, withhealing abutments rn ptsce The palalalflap has been positioned veslibuiarly toobtain 3 mm of attached gingiva.

Fig 17 (right) Second surgical phase.

Fig 18 (left] View ofthe ridge, which hasa thict;ness stabilized at 5 mm with goodminera liza lion ofthe biograh material andPRP gel afler oniy 3 months. The consis-tency is notable and ¡he implants stable.

Fig 19 (right) Lateral view of the expand-ed ridge rn which rt is possible to see theintegrity ofthe cortical wall. The photoshows heauy bleeding because oí 2 lac-tors' (1 ) ihe wound was opened after only3 months; and (2) it was necessary to use alocal anesthetic with anty a small percent-age of adrenaline because ofthe patient'shypertension.

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encourage medullar bleeding (Fig10), The bone defect obtained bythe separation of the bone flaps wasfilled with Biogran (Orthovita), abioactive glass synthetic bone graftmaterial, and autogenous platelet-rich plasma (PRP) gel activated withBotropase (Botropase batroxobina,AlC Ravizza Farmaceutici) (Fig 11),which was then compacted andmeasured with a periodontal probe;the ridge then had a thickness of 5mm (Fig 12), The ridge was coveredwith a PRP membrane (Fig 13) toprotect and stabilize the graft. Theflaps were then sutured on 2 sideswith horizontal mattress stitches(Vicryl # 4/0, Fthicon/Johnson &Johnson) (Fig 14),

Three months after the ridgeexpansion, the second operationwas performed to discover whetherthe implants had taken. At this timeit was possible to see the implantsunder the mucosa in the absence ofkeratinized tissue (Fig 1 5), A palatalincision was made to design a flap ofmixed thickness that opened towardthe vestibule to guarantee about 3mm of adherent gingiva on thevestibular side of the healing abut-ments (Fig 16), The ridge was wellmineralized with a thickness of 5 mm(Figs 17 and 18), the implants wereosseointegrated, and there was nosign of dehiscence or fenestrationon the vestibular side (Fig 19),

Result5

During the second surgery, whichwas carried out after 12 weeks,the bone ridge appeared to be

stabilized at a thickness of 5 mm, anincrease of 2 to 3 mm. The implantswere stable and perfectly osseoin-tegrated. The bone fracture rimasof the releasing incisions appearedsecure. The bioactive glass with PRPappeared to be mineralized. Thevestibular and palatal cortical sur-faces were eutrophic and did notshow signs of dehiscence or fenes-tration.

Discussion

This work presents a pilot study forthe clinical use of piezoelectricsurgery to expand thin edentulousridges, even with a very mineralizedresidual bone crest. The possibility ofexpanding the ridge and positioningimplants in single-stage surgery hasbeen the object of continuous re-search in recent years. For example,the ridge expansion osteotomy ofSummers'""'* permits the position-ing of standard implants (3,75 mm)in ridges of about 4 mm in thickness.This technique provides for the ex-pansion ofa single implant site, mak-ing use of the characteristics of boneelasticity: the bone gradually cedesto pressure exercised from inside bythe positioning of osteotomes of in-creasing diameter until it is able toreceive an implant that stabilizes thenew thickness obtained from the dis-location of the bone tissue in thevestibular and palatal directions.

The osteotomy method is veryeffectiveinboneofquality 3 to 4 be-cause it offers better expansion andprimary stability. In the case of moremineralized bone (quality 1 to 2), this

method is limited by the physicalnature of the material, which lacksthe elasticity that can be overcomeby the mechanical pressure of theosteotomes; this necessitates the useof burs and osteotomes that mostlyleads to fractures that are responsiblefor notable dehiscence and/or fen-estration and loss of the primary sta-bility of the implants. Instead, inthese situations it is possible to usethe manually fractured bone flaptechnique, butonly with a ndgeofatleast 3 to 4 mm in thickness on thecortical side, and only if the ridgehas development with an increase involume in the apical direction.

When bone atrophy is moresevere because the edentulism islong standing, and the residual ridgeis less than 3 mm, the bone is oftenof a very mineralized quality charac-terized by 2 cortical bones separatedby a thin cancellous layer The reha-bilitation of such advanced anatomicsituations with implants has until nowbeen treated in 2 surgical stages, inthe first of which bone is grafted toincrease the volume, with implantplacement in the second.

The new piezoelectric ridge ex-pansion technique as demonstratedin this case report permits implanttherapy in anatomic situations pre-viously impossible in a single-stagesurgical operation. In fact, the use ofvariable-frequency piezoelectricenergy scalpels separates the boneflaps without the risk of accidentalfracture because of excessivetrauma. The case in this report wascharacterized by a severe anatomicdifficulty that required very carefulsurgical attention, but it is symbolic

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of how piezoelectric surgery can be

used to resolve not only simple cases

but also the more complex.

Conclusions

1. Simultaneous ridge expansion

and placement of implants can

be obtained in single-stage

surgery in an edentulous ridge

that is 2 to 3 mm in thickness

for its entire vertical extension.

2. The bone flap technique has

been used successfully in the

case of bone of quality 1 to 2

thanks to variable-frequency

piezoelectric energy scalpels.

3. Stimulation of the medulla was

performed with piezoelectric

tips at the interface of the

defect created by the bone

separation, where a PRP gel

and Biogran were inserted,

4. The piezoelectric ridge expan-

sion technique is a new and

promising procedure for ridge

expansion in all cases, particu-

larly in advanced ones; in fact,

the periimplant healing is very

predictable because it takes

place in a protected and well-

vascularized environment.

The author recommends the fol-

lowing sources for a complete un-

derstanding of the principles dis-

cussed in this article: (1) Lynch SE,

Genco RJ, Marx RE (eds). Tissue En-

gineering: Applications in Maxillo-

facial Surgery and Periodontics

(Chicago: Quintessence, 1999); and

(2) Buser D, Dahlin C, Schenk RK

(eds). Guided Bone Regeneration in

Implant Dentistry (Chicago: Quin-

tessence, 1994).

References

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2. Adell R, Lekholm U, Grondahl K,Brânemark P-l, Lindström J, Jacobsson M.Reconstruction of severely resorbed eden-tulous maxillae using osseointegrated fix-tures in immediate autogenous bonegrafts, (nt J Oral Maxillofac Implants1990;5:233-24ó.

3. Nevins N, Langer 6. The successful appli-cation of osseointeg rated implants to theposterior jaw: A long-term retrospectivestudy. Int J Oral Masillofac Implants1993:8:428^32.

4. Cawood Jl, Howell RA. A classification ofthe edentulou5 jaws Int J Oral MaxillofacImplants 1988:17:233-236.

5. Dahlin C, Sennerby L, Lekholm U, Linde A,Nyman S. Generation of new bone aroundtitanium implants using a membrane tecfi-nLque: An experimental study in rabbits. IntJ Oral Ma>!illofac Implants 1989:4:19-25.

6. Dahlin C, Gottlow J, Linde A, Nyman S.Healing of maxillary and mandibular bonedefects using a membrane technique. Anexperimental study in monkeys. Scand JPlast Reconstr Hand Surg 1990:24:13-19.

7. Dahlin C, Lekholm U, Becker W, BeckerBE, Higuchi K, Callens A, van SteenbergheD. Treatment of fenestration and dehis-cence bone defects around oral implantsusing the guided tissue regeneration tech-nique: A prospective multicenter study.Int J Oral Maxillofac Implants 1995:10:312-318.

8. Mellonig JT, Nevins M. Guided boneregeneration of bone defects associatedwith implants: An evidence-based out-come assessment. Int J PeriodonticsRestorative Dent 1995:15:168-185.

9. Nevins M, Mellonig JT. Enhancement ofthe damaged edentulous rdge to receivedental implants: A combination of allo-graft and the Gore-Tex membrane. Int JPeriodontics Restorative Dent 1992;12:97-ni.

ID. Nevins M, Mellonig JT. The advantagesof localized ridge augmentation prior toimplant placement A staged event. Int JPenodontics Restorative Dent 1994:14:97-111

11 Buser D, Dula K, Belser U, Hirt HP,Berthold H Localized ndge augmenta-tion using guided bone regeneration. I.Surgical procedure in the maxilla. Int JPeriodontics Restorative Dent 1993:13:29-45.

12. Hammerle CHF,SchmidJ,OlahAJ, LongNP. A novel model system for the studyof experimental guided bone formationin humans. Clin Oral Implants Res 1996;7:38-47.

13. von Arx I, Hardt N, Wallkmanin B. TheTIME technique: A new method for local-ized alveolar ridge augmentation pnor toplacement of dental implants. Int J OralMaxillofac Implants 199ó;11:387-394.

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15. Summers RB. The osteotome technique:Part 2—The ridge expansion osteotomy(REOl procedure. Compendium 1994:15:422-426

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