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A Retrospective Analysis of Patients Referred for Implant Placement to a Specialty Clinic: Indications, Surgical Procedures, and Early Failures

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Purpose: This retrospective study analyzed the pool of patients referred for treatment with dental implants over a 3-year period in a referral specialty clinic. Materials and Methods: All patients receiving dental implants between 2002 and 2004 in
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  The International Journal of Oral & Maxillofacial Implants 1109 A Retrospective Analysis of Patients Referred forImplant Placement to a Specialty Clinic:Indications,Surgical Procedures,and Early Failures Michael M. Bornstein, Dr Med Dent 1  /Sandro Halbritter, Dr Med Dent 2  /Hendrik Harnisch, Dr Med Dent 2  /Hans-Peter Weber, Prof Dr Med Dent 3  /Daniel Buser, Prof Dr Med Dent 4 Purpose: This retrospective study analyzed the pool of patients referred for treatment with dentalimplants over a 3-year period in a referral specialty clinic. Materials and Methods:  All patients receiving dental implants between 2002 and 2004 in the Department of Oral Surgery and Stomatology, Univer-  sity of Bern, were included in this retrospective study. Patients were analyzed according to age,  gender, indications for implant therapy, location of implants, and type and length of implants placed. Acumulative logistic regression analysis was performed to identify and analyze potential risk factors for complications or failures. Results:  A total of 1,206 patients received 1,817 dental implants. The groupcomprised 573 men and 633 women with a mean age of 55.2 years. Almost 60% of patients were age50 or older. The most frequent indication for implant therapy was single-tooth replacement in the max- illa (522 implants or 28.7%). A total of 726 implants (40%) were inserted in the esthetically demand- ing region of the anterior maxilla. For 939 implants (51.7%), additional bone-augmentation procedureswere required. Of these, ridge augmentation with guided bone regeneration was performed more frequently than sinus grafting. Thirteen complications leading to early failures were recorded, resulting in an early failure rate of 0.7%. The regression analysis failed to identify statistically significant failureetiologies for the variables assessed.  Conclusions: From this study it can be concluded that patientsreferred to a specialty clinic for implant placement were more likely to be partially edentulous and over 50 years old. Single-tooth replacement was the most frequent indication (> 50%). Similarly, additionalbone augmentation was indicated in more than 50% of cases. Adhering to strict patient selection criteriaand a standardized surgical protocol, an early failure rate of 0.7% was experienced in this study population. I NT J O RAL M AXILLOFAC I MPLANTS 2008;23:1109–1116. Key words: dental implants, early failure, guided bone regeneration, indications, sinus grafting procedures T he replacement of missing teeth with endosseousimplants for the rehabilitation of completely orpartially edentulous patients has become a standardof care in dentistry in the past 20 years.This signifi-cant progress in implant dentistry is based on theconcept of osseointegration first described by theresearch groups of Brånemark et al 1,2 and Schroederet al. 3,4 These fundamental experimental studiesdemonstrated that titanium implants regularly healwith direct bone-to-implant contact,a processtermed osseointegration or functional ankylosis .In the past 2 decades,many clinical studies havedemonstrated that implant integration can beachieved and maintained in various areas of the 1 Assistant Professor, Department of Oral Surgery and Stomatology,School of Dental Medicine, University of Bern, Switzerland. 2 Resident, Department of Oral Surgery and Stomatology, Schoolof Dental Medicine, University of Bern, Switzerland. 3 Professor and Chairman, Department of Restorative Dentistryand Biomaterials Sciences, Harvard School of Dental Medicine,Boston, Massachusetts; Visiting Professor, Department of OralSurgery and Stomatology, School of Dental Medicine, Universityof Bern, Switzerland. 4 Professor and Chairman, Department of Oral Surgery and Stoma- tology, School of Dental Medicine, University of Bern, Switzerland. Correspondence to: Prof Dr Daniel Buser, Department of OralSurgery and Stomatology, Freiburgstrasse 7, CH-3010 Bern, Switzer-land. Fax: +41-31-632 98 84. E-mail: daniel.buser@zmk.unibe.ch COPYRIGHT © 2008 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART OF THIS ARTICLE MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER  1110 Volume 23, Number 6, 2008 Bornstein et al mouth on a long-term basis using different implantsystems.Good long-term documentation is availablefor several commercially available implant systems,including the Brånemark System (Nobel Biocare,Göteborg,Sweden),the Straumann Dental ImplantSystem (Straumann,Basel,Switzerland),the OsseotiteImplant System (3i/Implant Innovations Inc,PalmBeach,FL,USA),and the Astra Tech Dental ImplantSystem (Astra Tech,Mölndal,Sweden).For these sys-tems,prospective long-term studies have exhibited survival and success rates clearly exceeding 90% at5- and 10-year follow-ups. 5–16 Based on these scientific findings,osseointegrateddental implants have become a routinely used ther-apy in private practice.Because of the predictabilityof osseointegrated implants,treatment planning indental medicine has changed significantly in the past15 years. 17 The tremendous expansion of implanttherapy observed in private practice has mainly beencaused by the following aspects 18,19 :( 1 ) much betteracceptance of implant therapy by patients and clini-cians;( 2 ) the broadened spectrum of indications forimplant therapy in partially edentulous patients;( 3 ) the simplification of implant therapy,especially inuncomplicated cases,for example,with shortenedhealing periods using implants with microrough surfaces;( 4 ) the tremendous progress with bone augmentation procedures that enable implant place-ment in sites with local bone deficiencies.The aim of the present study was to evaluate thepool of implant patients referred by their dentalpractitioners to the Department of Oral Surgery andStomatology at the University of Bern for implantplacement over a 3-year period (2002 to 2004).Thepatient cohort was analyzed according to indicationfor implant therapy,age,gender,and need for boneadditional augmentation procedures.Furthermore,complications leading to early failure during thehealing period,ie,prior to prosthetic reconstruction,were analyzed. MATERIALS AND METHODS Patient Selection All patients receiving dental implants after beingreferred to the Department of Oral Surgery andStomatology,School of Dental Medicine,Universityof Bern,Switzerland,during a 3-year period from2002 to 2004 were included in this study.Candidateswith severe systemic health problems (immunocom-promised patients,patients with irradiated bone,etc)were excluded,but patients with local maxillary ormandibular bone defects requiring local horizontalbone augmentation or sinus floor elevation proce-dures,along with smokers,were included.In heavysmokers,staged augmentative procedures were notperformed. Clinical Procedures Surgical procedures were carried out under local anes-thesia (Ultracain DS forte,Aventis Pharma,Zurich,Switzerland) employing a low-trauma surgical tech-nique.All patients received premedication withatropine (0.5 mg intramuscularly) and antibiotic pro-phylaxis beginning 2 hours prior to surgery (Aziclav,1 g two times per day for 6 days;Spirig Pharma,Egerkingen,Switzerland).All implants were placedusing a standardized surgical procedure by 14 differ-ent surgeons.Four were experienced senior surgeons(inserting 881 implants/48.5%) and 10 were postgrad-uate students in oral surgery (inserting 936 implants/51.5%).The postgraduate students always had theassistance of an experienced instructor during surgeryfor quality assurance purposes.Details of presurgicalevaluation,surgical techniques,and postoperativetreatment have been previously published. 20–22 After a healing period of 6 to 8 weeks (for implantsinserted without bone augmentation) or 10 to 14weeks (after local bone augmentation or sinus floorelevation),prosthetic rehabilitation was initiated bythe referring practitioners in their private offices. Statistical Analysis The following parameters were evaluated usingdescriptive methods (Excel for Office XP/2000,Microsoft,Redmond,WA,USA):•Indication for implant placement.For all patients,the indication for insertion of an implant wascharacterized as edentulous jaws,distal-extensionsituations,extended edentulous gaps,and single-tooth gaps.•Distribution of implants by location.The locationwas determined by the exact tooth replaced by animplant;the jaws were grouped into 4 quadrants(anterior = canine to canine,posterior = premolars Table 1Age Distribution of Patients ReceivingDental Implants During the Years 2002–2004 Age No. of patients%WomenMen ≤ 20 y494.1252421–30 y1048.6545031–40 y13411.1726241–50 y22118.310711451–60 y33928.117916061–70 y26622.114911771–80 y816.74041> 80 y121.075Total1,206100633573 COPYRIGHT © 2008 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART OF THIS ARTICLE MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER  The International Journal of Oral & Maxillofacial Implants 1111 Bornstein et al and molars,in each arch).Additionally,implantsplaced in the so-called esthetic region of themouth (maxillary left first premolar to right firstpremolar) were analyzed.•Distribution of implants by diameter and length.•Type of augmentation procedure.Implants wereclassified as inserted with simultaneous guidedbone regeneration (GBR),staged GBR,or sinusfloor elevation (SFE) either by a simultaneous orstaged lateral window technique or simultaneousosteotome technique.•Analysis of complications and early failures.Implants inserted without additional augmenta-tion techniques were followed up after 1,2,and 6 to 8 weeks postoperatively before patients werereferred back to their restorative clinicians.Implantsplaced with a GBR or sinus graft procedure wererecalled after 1,2,4,8,and 10 to 14 weeks followingsurgery.Implants that failed to integrate and subse-quently had to be removed during the initial heal-ing period were classified as early failures.To identify potential factors for increased failurerisk,a multiple cumulative regression analysis wasperformed using the SAS 9.1 program (SAS Institute,Cary,NC).The dependent variable was the perfor-mance of the implant in the initial healing period(success/failure).Influencing variables were age,gen-der,smoking status (none/light/heavy),indication forimplant placement,implant location,implant diame-ter and length,and type of augmentation procedureused in combination with the inserted implant (noaugmentation/any type of augmentation).The signif-icance level chosen for all statistical tests was P  < .05. RESULTS Descriptive Analysis of the Patient Pool Over the assessed 3-year period,1,206 patientsreceived a total of 1,817 dental implants with a sand-blasted and acid-etched surface (SLA) (StraumannDental Implant System,Straumann) at the Depart-ment of Oral Surgery and Stomatology.The groupcomprised 573 men and 633 women with a meanage of 55.2 years (range,18 to 92 years).Fifty-eightpercent of patients were over the age of 50 (Table 1).There were 965 nonsmokers,169 light smokers (1 to10 cigarettes per day),and 72 heavy smokers (11 ormore cigarettes per day). Indication for Implant Placement. The most fre-quent indication for implant placement was single-tooth gaps in the maxilla (522 implants/28.7%).Thiswas followed by extended edentulous gaps in themaxilla (274 implants/15.1%) and distal-extensionsituations in the mandible (258 implants/14.2%).A detailed analysis is presented in Table 2. Distribution of Implants by Location. The mostfrequent location for implant placement was the firstmolar region in the mandible (320 implants/17.6%),followed by the central incisor area in the maxilla(240 implants/13.2%) and the first premolar locationin the maxilla (227 implants/12.5%) (Table 3).Implants were indicated more often in the maxillathan in the mandible (1,077 implants versus 740implants),and implant placement in posteriorregions of the jaws was more frequent than in ante-rior regions (1,158 implants versus 659 implants)(Table 4).A total of 726 implants (40% of all implants)were placed in the esthetically demanding anteriorregion of the maxilla (maxillary left premolar to rightfirst premolar). Table 2Distribution of Implants Placed in the Years 2002–2004 (n = 1,817)According to Indication PatientImplantSubtotal CombinedSubtotalCombinedIndication/regionNo.(%)(%)No.(%)(%) Single-tooth gapMaxilla46938.956.252228.741.3Mandible20817.322912.6Distal extensionMaxilla1149.421.122712.526.7Mandible14111.725814.2Extended edentulous gapMaxilla13110.917.227415.122.6Mandible766.31367.5Edentulous jawMaxilla161.35.5553.09.4Mandible514.21166.4Total1,206100.0100.01,817100.0100.0 COPYRIGHT © 2008 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART OF THIS ARTICLE MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER  1112 Volume 23, Number 6, 2008 Bornstein et al Distribution of Implants by Diameter and Length. The standard implant diameter of 4.1 mm (1,003implants/55.2%) and implant lengths of 10 mm (808implants/44.4%) and 12 mm (790 implants/43.5%)were most frequently used (Table 5). Type of Augmentation. A total of 939 implantsites (51.7%) needed some type of bone augmenta-tion procedure.Implants requiring bone augmenta-tion with the GBR technique were more frequentthan those needing sinus floor elevation procedures(722 implants versus 201 implants) (Table 6).A sepa-rate analysis of implants placed in the anterioresthetically demanding region of the maxilla showedthat a total of 542 implants needed a simultaneous(447 implants) or staged (95 implants) GBR proce-dure.This means that almost three fourths (74.7%) of the 726 implants inserted in this area required addi-tional local bone augmentation. Clinical Observations and Complications Following surgery,patients reported no or only mod-erate discomfort in the areas of surgery.In 37patients (3.1% of the 1,206 patients treated),postop-erative bleeding was observed,which could be con- Table 3Distribution of the Implants (n = 1,817) According to Location* Ma xilla17 (2)16 (3)15 (4)14 (5)13 (6)12 (7)11 (8)21 (9)22 (10)23 (11)24 (12)25 (13)26 (14)27 (15)Total No. placed5759711649791151258150111858721,077 Mandible47 (31)46 (30)45 (29)44 (28)43 (27)42 (26)41 (25)31 (24)32 (23)33 (22)34 (21)35 (20)36 (19)37 (18)Total No. placed1715163526111981059436816919740 *FDI notation used, with Universal numbers in parentheses. Table 4Distribution of the Dental Implants in Different Regions of Each Jaw RegionImplants% Anterior maxilla 50027.5Posterior maxilla57731.7Anterior mandible 1598.8Posterior mandible58132.0Maxillary implants1,07759.3Mandibular implants74040.7Anterior implants65936.3Posterior implants1,15863.7 Anterior maxilla/mandible = canine to canine.Posterior maxilla/mandible = premolars/molars in each arch. Table 5Distribution of the Inserted Implants (n = 1,817) by Type and Length No. placed% Implant typeStandard 4.1-mm1,00355.2Standard 4.8-mm25113.8Wide neck 4.8-mm27915.3Narrow neck 3.3-mm1518.3Standard 3.3-mm191.1TE1126.2Prototype implants20.1Implant length14 mm402.212 mm79043.510 mm80844.48 mm1548.56 mm251.4 TE = tapered effect implant design. Table 6Type of Augmentation Procedure Used in Combinationwith the Inserted Dental Implants (n = 1,817) Surgical procedureImplants% Implants with GBRSimultaneous GBR 59933.0Staged GBR 1236.7GBR total72239.7Implants with SFESimultaneous osteotome technique351.9Simultaneous window technique1065.8Staged window technique603.3Sinus graft total20111.0Implants with simultaneous SFE and GBR160.9Total implants with augmentation procedures (GBR and/or SFE)93951.7Implants without augmentation procedures87848.3 COPYRIGHT © 2008 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART OF THIS ARTICLE MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER  The International Journal of Oral & Maxillofacial Implants 1113 Bornstein et al trolled with local hemostatic measures.Temporaryhypesthesia of the regional nerve was found in 15patients (1.2% of the 1,206 patients treated),but nopermanent hypesthesia or anesthesia was observed.In 12 patients the inferior alveolar nerve was affectedand in 3 patients the infraorbital nerve was affected.Twenty-eight implants (1.5% of the 1,817 implantsinserted) showed signs of peri-implant inflammationduring the initial healing period.The inflammatoryprocess was contained and resolved with daily localdisinfection using 3% hydrogen peroxide and 0.2%chlorhexidine gel for up to 1 week (Plak-Out Gel,Hawe Neos Dental,Bioggio,Switzerland).In 3 of the28 sites,the implants subsequently developed insta-bility and revealed a peri-implant infection with sup-puration,and were therefore removed.Implant fail-ure during the healing period without any signs of inflammation or infection but with progressivemobility of the inserted implant was found in 10patients.The resulting total early failure rate was0.7% (13 of 1,817 inserted implants).The failuresoccurred in 10 different patients (6 men and 4women).Details on the 13 failed implants are pre-sented in Table 7.The remaining 1,804 implants showed healthyperi-implant tissues and remained stable throughoutthe healing period.The final clinical examination inthe Department of Oral Surgery and Stomatology,which occurred after 6 to 8 weeks for implants with-out augmentation procedures and after 10 to 14weeks for implants requiring local bone augmenta-tion,demonstrated healthy clinical and radiographicconditions.Subsequently,the patients were sentback to their restorative clinicians for the prostho-dontic phase of treatment. Regression Analysis The multiple cumulative regression analysis todetect contributing factors for early implant failurerevealed no statistically significant influence of age,gender,indication for implant placement,implantlocation (maxilla/mandible),implant diameter andlength,or type of augmentation procedure used incombination with the inserted implant (no augmen-tation versus any type of augmentation).Patientsmoking status did not appear to be a significant risk overall,although heavy smoking (> 10 cigarettes perday) came closest to being a statistically significantrisk factor. DISCUSSION The predictability of dental implants has introduceda significant change in treatment planning and treat-ment of fully and partially edentulous patients overthe past 10 to 20 years.Implants with enhanced sur-faces as currently in use reveal success rates of around 99% after 5 years of function,despite shorterhealing times of only 6 to 8 weeks. 23–27 Furthermore,the range of indications for dental implants hasbroadened tremendously,which is another impor-tant factor for the increasing popularity of implantdentistry among clinicians and patients.It has beenreported that over the past 2 decades the patientprofile has shifted more and more from the edentu-lous to the partially edentulous,including missingsingle teeth.In a survey of Swiss dental practitionersin the year 1994, 28 the most frequent indication forimplant placement was the edentulous mandible, Table 7Early Failures Among the Inserted Dental Implants* Smoking Implant Implant Augmentation ImplantAge (y)GenderstatusImplant site † Indicationlength (mm)typeprocedure 150MHeavy15 (4)Single-tooth gap10S 4.1No288FNo11 (8)Distal extension10S 4.1No313 (6)Distal extension12S 4.1No446FNo35 (20)Single-tooth gap10WN 4.8No562MNo15 (4)Distal extension10WB 4.8Staged SFE669FNo43 (27)Distal extension12S 4.1No736 (19)Single-tooth gap10WN 4.8No862MNo25 (13)Distal extension10S 4.8Simultaneous SFE967FNo44 (28)Single-tooth gap12NN 3.3Simultaneous GBR1016 (3)Single-tooth gap12WN 4.8Simultaneous SFE1169MHeavy33 (22)Edentulous12S 4.1No1271MNo34 (21)Single-tooth gap10TENo1319FLight34 (21)Extended edentulous gap10S 4.1Staged GBR *Early failure = during initial healing; 13 implants in 10 patients. † FDI notation used, with Universal Numbering System in parentheses.S = standard; WN = wide neck; NN = narrow neck; TE = tapered effect implant design; GBR = guided bone regeneration; SFE = sinus floor elevation. COPYRIGHT © 2008 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART OF THIS ARTICLE MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER
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