A Prospective, Multicenter, 4-Year Study of the ACE Surgical Resorbable Blast Media Implant

CLINICALA PROSPECTIVE, MULTICENTER, 4-YEAR STUDYOF THE ACE SURGICAL RESORBABLE BLASTMEDIA IMPLANTAron Gonshor, PhD, DDSGerald Goveia, DMDEmmanouil Sotirakis, DDSKEY WORDSClinical trialResorbable blast mediaDental implantsTitaniumAron Gonshor, PhD, DDS, is in privatepractice and is a lecturer at McGill University,Oral and Maxillofacial Surgery, Montreal,Canada. Address correspondence to DrGonshor at McGill University, Oral andMaxillofacial Surgery, 4980 Glencairn Avenue,Montreal, Quebec, Canada H3W 2B2 ([email protected]).Gerald Goveia, DMD, is in privatemaxillofacial practice in Brockton, MA.Emmanuel Sotirakis, DDS, is in privategeneral dental practice in Athens, Greece.174 Vol. XXIX/No. Four/2003This article reports on the 50-month results of the evaluation of the ACE Surgicalresorbable blast media (RBM) dental implant. There were 1077 implants placedin 348 patients: 950 in the mandible and 127 in the maxilla. A total of 78.6% ofthe implants were used to support anterior, mandibular, bar-retainedoverdentures. The 3.75- to 4.00-mm-diameter implant was used in 91.1% of cases,with the remainder being 3.3 mm (2.2%) or 4.75 mm (6.7%). The implants of 10-,13-, and 15-mm lengths were used in almost equal amounts in the mandible,maxilla, and anterior or posterior aspects of either jaw. There were 7 failures, allin the mandible and before stage 2 surgery. The overall implant success rate inthis 50-month interim report is 99.3% in the mandible and 100% for the maxilla.There was no discernible crestal bone loss during the study period. Nodifferences in bone response were seen in RBM implants with roughened surfaceson the entire implant, up to the collar, or up to the first 2 threads below thecollar.M will prove the reliability topographic surface changestha n o ha es im- will a t g nolomentyofhsurftace techicstuMis toward the develop- vival.diany humanve shanwd animalt thhistoe miallsur an n o cti fun rm o d t field lant p m i thINTRODUCTIONuceh of the emphaso isa inyllularng-teactivityim.2-4plantThis may be critidcalcrologotow-and predictability of the clinical out- earlier bone-to-implant contact thancome. It has long been accepted that that with machined surfaces.5,6 Thispure titanium has excellent biocompat- would allow the bone to achieve aibility with bone and that there is di- functional osseous state more quicklyrect cellular attachment of bone to the and to resist functional loading sooner.oxide layer of the titanium, resulting in The most common methods used to alimplantstability.1 There is also increas- ter titanium implant surfaces are (1)ing evidence that modifying the sur- surface blasting,7 (2) plasma spraying,8face morphologic features, especially and (3) acid etching.9 Within the sursurfaceroughening, can influence cel- face blasting there are 2 main groups:Aron Gonshor et ala report of the first 4 years of an ongoingprospective study designed toevaluate the clinical performance of anRBM roughened surface implant (ACESurgical, Brockton, Mass; Figure) invarious anatomic settings and prostheticrequirements.MATERIALS AND METHODSThe study involved 348 consecutive patientstreated during a 50-month period(March 1999 to January 2003) with prostheticloading. There were 8 indicationsfor implant placement, defined by arch,dentition, and type of prosthesis. Thecategories included a fixed prosthesison a totally edentulous maxilla (indication1) or mandible (indication 2) or apartially edentulous maxilla (indication3) or mandible (indication 4). A singleimplant, used to replace one tooth witha freestanding, single-unit prosthesis,was represented as indication 5 in themaxilla and indication 6 in the mandible,respectively. A removable prosthesis(overdenture) on implants in themaxilla (indication 7) or mandible (indication8) represented the final indications(Table 1).FIGURE. The ACE Surgical resorbable blast media implant.those created by media blasting, suchas aluminum oxide10 or titanium oxide,11 and those using calcium phosphateas a resorbable blast media(RBM).12 The latter method creates atextured surface by blasting a traditionalmachined titanium implant withcalcium phosphate ceramic, which isthen passivated without acid etching toremove residual media. This article isDuring the yearly evaluation visit,the prostheses were removed and examinedclinically for signs of movementor pain. Mobility was determinedby horizontal force with hand instruments.Calibrated panoramic radiographswere taken preoperatively, atsecond-stage surgery, after prosthesisdelivery, and once a year thereafter.Any significant changes in crestal bonelevel adjacent to the implant were verified,noting change as the differencesin the distance from the abutment-implantjunction to the bone level on bothmesial and distal surfaces. If there wasbone loss that required bone graft therapy,it was considered a failure. Thecriteria for success or failure werebased on implant integration ratherthan the functional viability of theprosthetic result. Osseointegration wasdetermined on the basis of the absenceof clinical signs of pain, mobility, in-flammation, infection, or the absence ofany radiolucency. Any detectable mo-Journal of Oral Implantology 175ACE SURGICAL RBM IMPLANTTABLE 1Implant in relation to prosthetic indication1 2 3 4 5 6 7 8 Implant5 3645815510AnteriorPosteriorTotal (N 5 1077)7.5 0.950.5 %bility or continuous crestal bone losswas considered a failure. Loosening orfracture of prosthetic screws was notconsidered a failure.The surgical and restorative guidelinesand patient selection followed therecommendations and guidelines thatare widely accepted today. Those patientswith histories of alcohol, tobacco,or other drug abuse, immunodeficiencies,uncontrolled diabetes, and radiationtherapy were excluded from thestudy. All patients received initial consultationand evaluation from both thesurgeon and the restorative dentist. Alloptions, limitations, and complicationswere discussed with the patient, and,when indicated, oral pathologic abnormalitieswere removed before the stage1 surgery. All implant surgery in thisstudy was performed under local anesthesiaon an outpatient basis. The incisionwas always midcrestal and osteotomiesfor the implants created inrelation to the requirements for eachimplant diameter. The implant, withcover screw in place, was seated so thatthe head of the cover screw was at theheight of the alveolar bone crest. Allpatients received oral antibiotics on aprophylactic basis. The use of chlorhexidinedigluconate (0.12%) mouth rinsewas routine, and patients were asked torefrain from wearing a prosthesis for14 days. Visits were scheduled for 1and/or 2 weeks postoperatively. For allpatients, existing prostheses were relievedand relined with appropriatesoft-line materials, and patients wereinstructed to maintain soft diets duringthe first 2 to 4 weeks after stage 1surgery.The stage 2, or abutment, surgerywas performed after a minimum of 3176 Vol. XXIX/No. Four/2003Indications846 8 220222673346872 84678.680.7 2.0 3.1 6.7months in the mandible and 6 monthsin the maxilla. This healing phase wassometimes extended, dependent on theassessment of bone quality by the surgeonat stage 1 surgery. At stage 2 surgery,the implants were tested for mobilityand temporary healing abutmentsplaced. A border of attachedgingiva was created around the healingabutments whenever possible.Final abutment connection wasperformed 2 to 4 weeks later, allowingtime for gingival healing. The selectionof the final abutment was most oftenleft to the restorative dentist and wasdependent on multiple factors, includinginterarch space, angulation of theimplant, esthetics, and the requirementsof the remaining prosthodontictreatment. Starting in the year 2000,stages 1 and 2 were combined as a1-step procedure for 20 implants in 8patients. The implant was placed in theusual fashion. A cylindrical hexedabutment with a separate center screwwas then attached as the mucosal elementand covered with a healing cap.This assembly was not loaded, and atemporary prosthesis with soft-lineconditioner was placed 2 weeks afterimplant placement. Patients were seenafter prosthesis delivery and the follow-up time began from that date. Appropriateclinical examination and radiographsconfirmed stability of theentire assembly and hygiene instructionswere given. Visits were thenscheduled at 6-month intervals for thefirst year and once a year thereafter.RESULTSDuring a 50-month period, from October1998 to January 2003, patientsunderwent rehabilitation using theACE Surgical endosseous RBM-surfacedimplant. At the time the datawere analyzed, patients with 6 implantswere lost to follow-up. One ofthese patients had relocated. Three othersrefused to return for follow-up.This left a total of 348 patients, consistingof 243 women (64.3%) and 105men (27.8%) and providing a femalemaleratio of 2.3:1. This also representeda total of 1077 implants, with 950(88.2%) placed in the mandible and 127(11.8%) in the maxilla. The age distributionof patients extended from 17 to81 years, with a mean 6 SD age of 556 11 years. There was no significantdifference in the age of women andmen. The largest percentage of the patientpopulation was in the 51- to 60-year age grouping (38.8%). The agegroup of 41 to 70 years represented81.9% of the entire population and thelargest percentage of implants (88.3%).The overwhelming number of implants(79.3%) was used for bar-retained overdentures(indications 7 and 8), with78.6% of these implants in the anteriormandible (Table 1).This study used the ACE SurgicalRBM screw implants in diameters of3.3, 3.75, 4.00, and 4.75 mm. Thelengths were 8, 10, 13, 15, and 18 mm.The 8-mm length was used in one caseonly and consisted of 4 implants of the4.75-mm diameter for a mandibularanterior overdenture. Most implants(Table 2) were 3.75 or 4.00 mm in diameter(91.1%), with the remainder being3.3 mm (2.2%) or 4.75 mm (6.7%).The implant lengths of 10, 13, and 15mm were used in almost the sameamounts in the mandible, maxilla, andanterior or posterior aspects of eitherjaw, respectively.For the purposes of this study, eachimplant came in 1 of 3 surface configurations.The first configuration had avariable surface with a machined implantsurface down to the secondthread, with the remainder being anRBM surface. The second configurationwas an RBM surface from the apex upto the collar. The third configurationwas a machined implant surface withLength (mm)810131518Total No. (%)No. of implantsMedianMinimumMaximumMean (SD)*Time 1 was between first stage and last follow-up (January 2003). Time 2 was betweenprosthetic lodading and last follow-up (January 2003).no RBM treatment. These groups wereplaced randomly, with no regard tobone type or jaw region. In addition, inthe 3.75- to 4.00-mm diameter, 10 implantsin each of the 3 lengths werealso made available with an RBM surfaceon their entire length, includingthe collar. The variable RBM surfacerepresented more than 60% of the implantsin the 3.75- to 4.00-mm diameter.In the 3.3- and 4.75-mm diameter,the implants with RBM up to the collarrepresented more than 60%. In all clinicaland radiographic assessments, nodifferences have been apparent amongthe 4 categories up to this follow-upperiod.Seven implants, in 4 patients, failedto integrate. Three implants failed inthe posterior and 4 in the anteriormandible, all before stage 2 surgicalprocedures. Two of the posterior implantswere in one patient and 3 anteriorimplants in another patient. Inboth cases, the implants were placed asa 1-step procedure and became mobile3 to 4 weeks after insertion. The remainingposterior implant was removeddue to a complaint of implantrelatedpain. The remaining anteriorimplant exhibited mobility duringmanual examination.TABLE 2Implant distribution by diameter and lengthDiameter (mm)3.75 3.35135020324922816696 (64.8) 23 (2.2)TABLE 3Life table analysis*Time 1 (mo)107736.712.650.833.1 (19.2)Total No. (%) 4.75 4.0010182013 (1.7)329 (37.7)384 (43.7)335 (37.8)16 (1.7)1077 (100.0)3103102780286 (26.3)24072 (6.7)Time 2 (mo)94930.48.043.527.8 (16.8)A life table analysis of all the implants(Table 3) shows that the earliestimplants were in place for more than50 months, with the longest loadingperiod being 43.5 months. With no implantfailures after loading, the effectivesurvival rate for loaded implantsis 100% for the study period. No significantcrestal bone loss was seen inthe 50 months covered in this study.Fractures of implants, center screws, orprosthetic screws were not identifiedas problems.DISCUSSIONDuring the past few years, there hasbeen ever-increasing attention given toimplants with rough-textured surfaces,citing preclinical mechanical and animalstudies for acid etching,13 aluminum,14 titanium,11 grit blasting, andRBM preparation.10 Recent histologicstudies for both acid etching15 and mediablasting16 show high bone-to-implantcontact, indicating that the modifiedtopography of titanium implantsmay create favorable osteoconductivebehavior.Recently, Cooper,17 in a comprehensivereview, looked at the role ofsurface topography in creating andmaintaining bone at titanium implantsAron Gonshor et aland concluded that the increased surfaceimproves bone-to-implant contactand mechanical properties. In addition,Davies18 hypothesized that improved''wettability'' and increased clot retentionon the roughened surfaces resultedin improved osseointegrationthrough mechanisms that promote osteoconductionat the titanium surface.Buser et al19 studied bone-to-implantresponse in long bones of miniaturepigs, using implants with 6 differenttreated surfaces. They demonstrated apositive correlation between increasedroughness values and bone-to-implantcontact. After 6 weeks, the roughest surfacehad the greatest amount of bonecontact. This has been confirmed byCochran et al.12 Wennerberg et al20 comparedimplants with 2 different blastsurfaces and machined implants in rabbitbone. Although each surface showeddifferent degrees of roughness, the blastedsurfaces showed stronger bone fixationby virtue of significantly greater removaltorque values and percentage ofbone-to-implant contact.It is now well established that optimalbone cell apposition occurs at ahigher percentage on surfaces that areroughened compared with machined.21-23Two studies by Piattelli et al,24,25 comparingbone response in rabbits to machinedand RBM titanium implants,showed a significantly higher boneimplantcontact percentage with theRBMimplants. Their conclusionwas thatthe RBM surface could be consideredmore osteoconductive than one that ismachined. Similar results were obtainedin another recent study in which scanningelectron microscopy and electronspectroscopy for clinical analysis of machinedand sandblasted and acid-etchedsurfaces showed that increased implantroughness can improve in vitro cellularadhesion and proliferation.26 The increasedsurface area created by a roughenedsurface permits more area for bonecell attachment. A machined implantwould need to be 30% to 40% larger toachieve a similar surface area.If surface morphologic features areaccepted as being a critical character-Journal of Oral Implantology 177ACE SURGICAL RBM IMPLANTistic for enhancing the bone-to-implantcontact, identification of the optimalsurface for bone cell formation is stillin the early stages. Currently, as describedin the literature, osseointegrationhas been enhanced as a directfunction of the increased surface area,when the dental implant surface isroughened rather than left smooth.Based on this information, defining theoptimal roughened surface has beendescribed by both the implant surfaceroughness (Ra), which is the arithmeticaverage of the deviation of peaks andvalleys from a mean line on the surfaceof the implant, and the micropit diametersin this roughened surface. Ingeneral, the literature has described theoptimal Ra range as 2 to 4 mm and themicropit diameters of this roughenedsurface as 3 to 11 mm. The ACE SurgicalRBM implant has an average surfaceRa of 3.09 mm, with micropit diametersthat range from 5 to 10 mm,27placing it entirely within the desiredoptimal surface characteristics for bothparameters.Buser et al28 studied removaltorque in acid-etched (3i Osseotite, 3i,Palm Beach Gardens, Fla) and sandblastedand acid-etched (StraumannSLA, Institut Straumann, Waldenburg,Switzerland), surface-treated implants.The removal torque is the amount oftorque required to screw an implantout of bone and is considered a roughmeasure of osseointegration. The removaltorques were significantly higherfor the SLA implant.The SLA and Osseotite Ra's are 2and 1.3 m, respectively, with a 1- to 2-mmicropit diameter for both. The ACESurgical RBM implant, with a slightlyrougher surface than the SLA implant,but still in the optimal range, wouldseem to offer the same characteristicsof early bone apposition as the SLAimplant.A 5-year study of the IMZ titaniumplasma-sprayed cylinder implants reportedsuccess rates of 95.8% for themandible and 92.9% in the maxilla.29Babbush and Shimura,30 in a 5-year lifetable statistical analysis and clinical ob-178 Vol. XXIX/No. Four/2003servation of the IMZ implants, showedan overall 95.0% survival rate. Bothpartially and totally edentulous patientswere at the 96.0% rate, with themaxilla at 92.0% and the mandible at99.0%. They noted that the major factorsthat positively influenced longtermsurvival were the use of the longestand largest diameter implants appropriatefor the clinical situation. Leimola-Virtranen et al,31 using ITItitanium, plasma-sprayed screw implantsin the edentulous mandible andwith up to a 10-year follow-up, wereable to show overall success rates of94.9%. A study on partially edentulouspatients by Jemt and Lekholm32showed 5-year success rates of 97.2%.Zarb and Schmitt,33,34 using Nobelpharmaimplants, showed 94.3% successrates in patients with partially edentulousposterior areas and 91.5% in thepartially edentulous anterior regions.In a retrospective, multicenter reportof 3i implants during a 5-year period,Lazzara et al35 evaluated bothpure titanium threaded implants andtitanium plasma-sprayed implants intotally and partially edentulous patients.They calculated a mean implantsurvival rate of 95.0% for both thethreaded and cylindrical implants. Inparticular, the success rate for thethreaded implants was 97.0% in themandible and 93.8% in the maxilla.More recently, Davanpanah et al,36in a prospective 3-year evaluation ofthe 3i ICE implants, showed 94.3% and92.9% survival rates after 1 and 3 yearsof prosthetic loading, respectively. Therate of late failures (4.7%) was greaterthan the rate for early failures (2.3%).In a 4-year interim report on the Osseotiteimplant,37 the cumulative successrate was 98.7%, with a 99.4% successrate in the posterior mandible and98.4% in the posterior maxilla, with nofailures after loading.Similar results were achieved byGrunder et al,38 whose 5-year reportwith the Osseotite implant showed a100% cumulative survival rate in anteriorimplants and 98.4% for posteriorimplants. The cumulative postloadingimplant survival rate was 100% forboth anterior and posterior implants.This may suggest that the surface cansignificantly reduce postloading failures,thereby providing a high level ofprosthetic predictability. These resultsare markedly different from those seenwith machined-surface implants,where late failures accounted for nearlyhalf of all the reported failures.15,39A 5-year follow-up report on theITI, nonsubmerged, solid screw implantwith blasted surface40 showed acumulative survival rate of 95.3%,which was comparable to the 5-yearsurvival rates with the submerged Branemarksystem implant.41 The presentstudy, which shows success rates of99.3% for the mandible and 100% forthe maxilla, is similar to the previouslymentioned results. There was no differencein the rates based on implantlength or prosthetic indication, althougha longer follow-up time will berequired before a more definitive statementmay be made. Within the numberof implants considered as failures, lossof integration was the major cause, althoughthe incidence was so small thatit cannot be seen to represent a significantoverall problem. The fact thatsome of these failures were in the1-step procedure highlights the need tostudy the long-term success rates withthat technique.Dental implants of high quality, eithertitanium screw design or the titaniumcylindrical form with a plasmasprayedsurface, achieve osseointegrationwith high success rates. Therefore,choosing an implant system that ismanufactured from high-strength biocompatiblematerials, structurallyhigh-tolerance design features, andclose-fitting tolerances will promote itsfunctional success.In conclusion, the success rates inthe present interim clinical study showthat the ACE Surgical RBM implant iscomparable to other similar implantsin terms of implant survival and prostheticstability. These success rates arehigh, independent of the variety ofclinical situations in which they areused, and influenced by careful caseplanning and communication of thesurgical and prosthetic teams. 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