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Froum.qxd 1/23/06 10:57 AM Page 71 A Retrospective Study of 1,925 Consecutively Placed
Immediate Implants From 1988 to 2004
Barry Wagenberg, DMD1/Stuart J. Froum, DDS2 Purpose: The purpose of the present study was to evaluate implant survival rates with immediateimplant placement (IIP) into fresh extraction sockets and to determine risk factors for implant failure.
Materials and Methods: A retrospective chart review was conducted of all patients in whom IIP wasperformed between January 1988 and December 31, 2004. Treatment required atraumatic toothextraction, IIP, and mineralized freeze-dried bone allograft with an absorbable barrier to cover exposedimplant threads. Implant failure was documented along with time of failure, age, gender, medical his-tory, medications taken, postsurgical antibiotic usage, site of implant placement, and reason forimplant failure. Statistical analysis was performed using chi-square and logistic regression analysismethods. Results: A total of 1,925 IIPs (1,398 machined-surface and 527 rough-surface implants)occurred in 891 patients. Seventy-one implants failed to achieve integration; a total of 77 implantswere lost in 68 patients. The overall implant survival rate was 96.0% with a failure rate of 3.7% pre-restoration and 0.3% postrestoration. Machined-surface implants were twice as likely to fail as rough-surface implants (4.6% versus 2.3%). Men were 1.65 times more likely to experience implant failure.
Implants placed in sites where teeth were removed for periodontal reasons were 2.3 times more likelyto fail than implants placed in other sites. Patients unable to utilize postsurgical amoxicillin were 3.34times as likely to experience implant failure as patients who received amoxicillin. Conclusions: With a1- to 16-year survival rate of 96%, IIP following tooth extraction may be considered to be a predictableprocedure. Factors such as the ability to use postsurgical amoxicillin and reason for tooth extractionshould be considered when treatment planning for IIP.
INT J ORAL MAXILLOFAC IMPLANTS 2006;21:71–80 Key words: age factors, dental implants, gender, implant surfaces, implant survival, penicillin allergy,smoking Ahigh level of predictability for implants placed rates of 99.1% in the mandible and 84.9% in the into fully and partially edentulous patients has maxilla.2 Unfortunately, during this extended postex- been demonstrated in many long-term studies.1–9 traction healing phase, resorption of the residual The procedure used in most of these studies includes bone occurs.
a 6- to 12-month healing period following tooth Studies have demonstrated that approximately extraction to allow implant placement into mature 45% of the residual alveolar ridge may be resorbed bone.1,10 Albrektsson and associates stated that this after tooth extraction, with the majority of resorption protocol resulted in 5- to 8-year implant success occurring during the first 6 months after extrac-tion.11,12 Without treatment, resorption is observed inall dimensions of the residual alveolar ridge follow-ing tooth extraction.13–15 Left uncontrolled, this 1Director of Dental Education, Newark Beth Israel Hospital, resorption could prevent routine implant placement.
Newark, New Jersey; Associate Clinical Professor, Department of Immediate implant placement (IIP) into an extrac- Periodontology and Implant Dentistry, New York University, New tion socket has been proposed as a method to pre- York, New York.
2Clinical Professor and Director of Clinical Research, Department serve bone at the surgical site.16–18 Other advantages of Periodontology and Implant Dentistry, New York University of IIP are a reduction in treatment time and the ability Dental Center, New York, New York.
to place the implants in positions that are favorable forthe final prosthesis.19 In addition, patient acceptance Correspondence to: Dr Stuart J. Froum, 17 West 54th Street, from the reduced number of surgeries and reduced Suite 1C/D, New York, NY 10019. Fax: +212 586 7599. E-mail: [email protected] treatment time is an advantage of this method.20 The International Journal of Oral & Maxillofacial Implants COPYRIGHT 2005 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.
Froum.qxd 1/23/06 10:57 AM Page 72 Two literature reviews found similar implant sur- 1. Apical or lateral stabilization. Upon surgical place- vival rates for immediate and delayed implant place- ment, the implants achieved stability in host ment. 19,21 Likewise, bone fill occurred with sub- bone. Dehiscence with thread exposure at the merged and nonsubmerged implant placement.22 time of implant placement did not prevent inclu- Studies describe a variety of techniques resulting in sion in the study if initial stability was obtained.
survival rates of immediate implants ranging from 2. Lack of residual infection. The extraction socket 89% (for molar replacement only) to 100%, with was examined after a thorough curettage remov- study durations ranging from 1 to 11 years.23–33 ing all residual fibers from the apical area and the Comparison of success rates and analysis of the lateral walls.
factors important for implant survival is difficult with 3. Continuous function for a period of 1 year the many variables included in the aforementioned postrestoration. If an implant failed prior to studies (ie, implant surface, use of bone graft and/or restoration placement this implant was included membrane barrier, primary closure of wound, reason in the statistical analysis and considered as a fail- for tooth extraction). In the present retrospective ure prior to final restoration.
study, protocol variation was controlled; the sametechniques (bone grafting and membrane use) were A consistent surgical protocol was followed. Local utilized for placement of all implants. The purpose of anesthesia was achieved through infiltration tech- the present study was to evaluate survival rates of niques (no regional block anesthesia) using lidocaine implants placed immediately into fresh extraction with 1:50,000 epinephrine (Abbott Laboratories) sockets and restored for a minimum of 1 year. An unless medically contraindicated. In patients where additional purpose was to correlate implant failure epinephrine was contraindicated, mepivacaine 3% rates with the age and gender of the patients, (Abbott Laboratories, North Chicago, IL) was used.
implant position, smoking habits, medications taken, Full-thickness flaps were elevated with minimal penicillin allergy, and reason for tooth failure.
palatal elevation in the maxilla. Vertical incisions wereutilized as necessary. The teeth to be removed wereextracted atraumatically whenever possible. Molars MATERIALS AND METHODS were sectioned and roots removed separately. Usinga bur, a trough was made around the circumference A retrospective chart review was conducted on all of the root through the ligament. The roots were patients treated with implants placed immediately removed with an elevator using minimum pressure.
into tooth extraction sites by a single periodontist.
Sockets were thoroughly degranulated with curettes Patients were identified through analysis of the or burs and inspected. All remnants of fibers and soft office database and through evaluation of data tissue were removed from the sockets.
recorded in an implant tracking software program Standard protocol and the manufacturer's recom- (Implant Tracker, West Hartford, CT). Once patients mendations were followed for drilling. Implant place- were identified, individual charts and radiographs ment varied by area and position of the remaining were evaluated, and the following data were bone. Implants in the esthetic zone were placed recorded: age at implant placement, date of implant slightly to the palatal, especially between the maxil- placement, gender, medical history, smoking history, lary right and left canines. Implants in the premolar medication usage, medical allergies, reasons for ini- area in the maxilla were placed to the palatal, but api- tial tooth failure, location of implant placement, addi- cally, through the remaining septum. In the mandibu- tional surgical procedures (eg, sinus lift), implant lar premolar area implants were placed into the cen- dimensions, implant manufacturer, date of abutment ter of the socket. In the maxillary and mandibular connection, date of final restoration seating, and, molar areas implants were placed slightly to the when applicable, date of and reasons for implant fail- mesial of the interradicular bone (most often utilizing ure. Restorative clinicians were contacted via tele- a wide implant, but not necessarily in contact with the phone survey to confirm the dates of restoration and buccal and lingual plates of bone). When sinus lifts determine whether there were any unreported com- were performed, either lateral windows were opened plications or failures of the immediately placed or osteotomes were utilized to complete the implant implants. Up-to-date monitoring with recall visits to preparation. An appropriate-length implant was the surgeon and restorative clinicians was performed placed, leaving the platform 1 to 2 mm apical to the for all patients and all implants placed through most coronal height of the remaining crest.
December 2004.
Mineralized freeze dried bone allograft (FDBA) Implants included in this review met the following (Miami Tissue Bank, University of Miami; Miami, FL) inclusion criteria: was tightly packed into the residual spaces around Volume 21, Number 1, 2006 COPYRIGHT 2005 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.
Froum.qxd 1/23/06 10:57 AM Page 73 the implant. A periodontal probe was utilized to Göteborg, Sweden, and Implant Innovations/3i, Palm push the bone into narrow spaces. Bone grafts were Beach Gardens, FL). The mean patient age at the time utilized in all cases in which there was a residual of surgery was 57.9 years, with a range of 14 to 94 space around the implant. A Vicr yl membrane years. A total of 1,925 implants were placed in fresh (Ethicon/Johnson & Johnson, Somerville, NJ) was cus- extraction sockets immediately following tooth tom cut, extended 5 to 7 mm beyond the margins of extraction. As of December 31, 2004, a total of 1,854 the defects and tucked under the flaps both labially implants had been restored for at least 1 year. A total and palatally (lingually) without suturing. The flaps of 1,398 machined-surface and 527 rough-surface were closed using chromic 4-0 gut sutures. No implants were placed. Thir teen implants in 10 attempt was made to advance the flaps and cover patients were placed in conjunction with lateral-win- the membrane (Figs 1a to 1g). Patients were premed- dow sinus lifts, and 148 implants in 111 patients were icated with amoxicillin (500 mg 4 times daily; TEVA placed using an osteotome internal sinus augmenta- Pharmaceuticals USA, Sellersville, PA) starting 2 days tion procedure. Nineteen implants in 7 patients were prior to the procedure and continuing for 10 days immediately loaded following placement. Forty-five postsurgery. Penicillin-sensitive patients were pre- implants in 40 patients received immediate nonoc- medicated with clindamycin (300 mg 4 times daily; clusally loaded provisional restorations following Watson Laboratories, Corona, CA) prior to surgery placement. The follow-up period varied between 12 and continuing for 10 days. The patients utilized and 193 months after delivery of the final prosthesis, .12% chlorhexidine gluconate (Peridex, Vila Pharma- with a mean follow-up period of 71 months. Failure ceutical, Phoenix, AZ) on a cotton tip to lightly clean to achieve or maintain osseointegration was seen in any exposed membrane area 3 times daily until the 68 patients, some of whom experienced more than 1 membrane was absorbed.
failure. A total of 77 implants were lost (42 in male Most implants were allowed to heal for 3 months patients; 35 in female patients). Of these failed in the mandible and 6 months in the maxilla prior to implants, 71 (92%) failed to achieve osseointegration second-stage surgery. In most cases final restoration and 6 (8%) failed to meet success criteria after final began within 3 weeks of second-stage surgery. Of restorations were placed.34 Nine patients experi- the implants that were immediately restored with enced multiple failures—1 patient lost 2 implants to provisional restorations, the same IIP protocol was progressive bone loss, 3 patients lost 2 implants each followed as to position of placement, use of graft and to nonintegration, 4 patients lost 2 implants each to membrane, and flap closure.
infection, and in 1 patient, 2 implants were removed Implant failure was recorded as "before final because of paresthesia. The reasons for implant fail- restoration" or "after final restoration." Whenever pos- ure as well as the reasons for the tooth loss that pre- sible the reason for implant failure was recorded.
cipitated the need for implant placement were docu- Implant survival was checked at the abutment con- mented (Table 1). The overall implant survival rate nection stage and at various intervals after place- was 96.0%, with implant failure rates of 3.7% prior to ment of the final restoration. Implant survival was restoration and 0.3% after restoration (Table 2).
defined by the criteria proposed by Albrektsson and Of the 1,398 machined-surface implants placed, 65 failed (4.6%). Of the 527 rough-surface implants Data analysis methods included chi-square analy- placed, 12 failed (2.3%). There was a statistically sig- sis for the evaluation of statistical significance and nificant difference in implant failure rate between logistic regression analysis for the evaluation of rough- and smooth-surface implants (P = .02). A total impact of demographic and clinical variables on of 1,602 implants were placed in nonsmokers, 1,162 implant survival. Data analysis software used was with machined surfaces and 440 with rough sur- JMP (SAS Institute, Cary, NC). The level (alpha) faces. A statistically significant difference between of statistical significance was .05.
the failure rates of smooth- and rough-surface (4.5%versus 1.8%) implants was documented (P = .01) innonsmokers.
A total number of 323 implants were placed in patients with a self-described smoking habit. Of these, Eight hundred ninety-one consecutively treated 18 failed (5.6%). Nonsmokers received a total of 1,602 patients (381 men and 510 women) in whom imme- implants of which 59 (3.7%) failed. The difference in diate implant surgery was performed between Janu- implant failure rate between smokers and nonsmok- ary 1988 and December 31, 2004 were evaluated ers was not statistically significant (P = .342). There through the study. All patients were treated with was no difference in the failure rate of rough-surface implants made by 2 manufacturers (Nobel Biocare, implants and that of smooth-surface implants in The International Journal of Oral & Maxillofacial Implants COPYRIGHT 2005 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.
Froum.qxd 1/23/06 10:57 AM Page 74 smokers (P = .6492). Fifty-one immediate implants Reasons for Tooth and Implant Loss were utilized to replace failed implants. Two of these failed, for a 3.9% failure rate, which was not signifi- cantly different than the failure rate in the general sur- vey population (P > .05).
Of the 1,094 implants placed in women, 34 failed for a 3.1% failure rate. Forty-three of the 831 implants placed in men failed, for a 5.2% failure rate. The rela- tive risk of implant failure in men was 1.65 times that for women (P = .0314, CI [1.04, 2.61]).
Two of 51 immediate implants placed to replace a failing implant failed, for a failure rate of 3.92%.
The mean age of women in this study was 57 years. The mean age of men was 59 years. This repre- sents a statistically significant difference in age in the study population (P < .001) No correlation was found between implant failure and age of the patient (P > .06).
There was no statistically significant correlation between implant failure and any single medication or combination of medications taken by patients in this study in whom implant failure occurred (P = .895). A significantly greater implant failure rate was linked to the high infection rate in patients who were unable to use postsurgical penicillin due to allergy, with penicillin-allergic patients demonstrating a rela- tive risk of 3.3 when compared to patients who were able to utilize penicillin (P < .01). Patients with an allergy to penicillin were 5.7 times more likely to experience implant failures due to infection than patients without allergy to penicillin (Table 3). There was no significant difference in implant failure rate associated with any medical condition of patients included in this study (P = .967).
A total of 383 implants were used to support sin- gle crowns. The remaining 1,471 implants were used Failure Rate of Implants Before and After Total implants placed Total implants failed Postrestoration failures Failures prerestoration Table 1 notes: Universal (FDI) tooth numbers shown. AB-PD = abscess periodontal disease; AB-PDD = periodontal abscess; ATI = adjacent tooth infection; D = distal; DEC = decay; FBG = failed block graft; I = infection; IL = immediate load; ISL = internal sinus lift; ITR = immediate tooth replacement; M = mesial; NI = noninte- PBL-VHS gration; O-O = occlusal overload; P = parasthesia; PAP = periapical pathology; PBL PBL-VHS = progressive bone loss; PDD = periodontal disease; RAB = refused antibiotic; RF = root fracture; TEP = trauma–epileptic patient; TLC = trauma from a loose crown; VHS = very heavy smoker; WSL = window sinus lift.
*After 9 y.
Froum.qxd 1/23/06 10:57 AM Page 75 in restorations supported by multiple implants, with Implant Failure in Patients with Penicillin 2 or more implants splinted to support the definitive prosthesis. There were no failures in the single-unit Number placed Number failed group, while 16 implant failures were seen in thesplinted group. This difference was not significant No penicillin allergy (P = .356).
Penicillin allergy A significant difference in implant failure rate by area of implant placement was seen (P = .001) (Table4). The area with the highest percentage of failureswas the mandibular anterior area, while the lowestpercentage of failure occurred in the maxillary Implant Failure by Location canine area.
One hundred twenty-two teeth were lost because of periodontal disease, while 1,803 teeth were lost for other reasons. The difference in implant failure between implants placed at the sites of periodon- tally diseased teeth and those placed in nondiseased sites was statistically significant (P = .02). Implants placed after tooth extraction because of periodontal causes were 2.3 times more likely to fail than implants placed after tooth extraction for nonperio- dontal reasons (Table 5).
The 96.0% survival rate of the 1,925 implants placed Implant Failure and Etiology of Tooth in the present study is similar to reports for implants placed in healed bone.35 This study reports on restorations that were in place at least 1 year post- loading, with a follow-up from 1 to 16 years, whichalso compares favorably with the time of follow-up in other studies. Using 2 electronic databases and having 1 individual enter all of the data minimizedthe possibility of undetected failures.
The current study demonstrates a statistically sig- shown that rough-surface implants can partially com- nificant difference in favor of rough surface implants, pensate for the negative healing response in but both surfaces demonstrated survival rates in smokers,46–48 the current study demonstrated no sig- excess of 95%. When considering implant placement nificant difference in implant failure in smokers, in healed bone, no significant differences were seen regardless of the type of implant surface. A number of relative to implant surface.36 With the reported factors may explain this lack of difference in implant advantage of roughened surfaces being improved failure rate in smokers compared to nonsmokers. In clot formation and increased bone-to-implant con- the present study, patients were categorized as smok- tact,37 it is possible that these factors play a role in IIP.
ers if they reported smoking more than 10 cigarettes In addition, during the early phases of IIP, only per day. There was no calculation made of how many machine-surfaced implants were used; consequently, of these patients smoked no more than 10 cigarettes.
a "learning curve" may have influenced implant fail- This may be an important issue, as the findings of a ure in that study group.
meta-analysis indicated that "light smoking" (average Although some studies have reported decreased of 12 cigarettes per day) did not affect the success implant survival in smokers,38–45 only 1 immediate rate of either machined or dual-acid-etched surface implant study reported the effect of smoking and implants.47 In the current study, absorbable mem- implant survival.46 In contrast to other reports, the branes were placed over FDBA and were often left results in the present study show no significant differ- exposed. Although smoking has been reported to ence in implant failure rate between smokers and have a detrimental effect on periodontal regenerative nonsmokers. Likewise, while some studies have procedures utilizing bioresorbable barriers in cases of The International Journal of Oral & Maxillofacial Implants COPYRIGHT 2005 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.

Froum.qxd 1/23/06 10:57 AM Page 76 Radiograph of maxillary left lateral incisor with a large periapical area. Clinical photograph following extraction, debridement of the socket, and placement of the immediate implant. Placement of mineralized FDBA to fill the defect. Placement of an absorbable membrane barrier over the graft and implant. Closure with absorbable sutures. Radiograph of the implant 5 years postloading. Clinical photograph of the implant restoration 5 years postloading.
molar furcations, the healing process may differ fol- Gender was seen as a significant risk factor for lowing immediate implant placement as performed implant failure (P = .0207) as the relative risk for fail- in the present study.49 Oral hygiene in the current ure in men showed a 5.05% failure rate compared to study included localized applications of chlorhexidine a 3.2% failure rate of IIP in women. The results of the 3 times a day until the membrane was absorbed. This present study are in agreement with a previously combined with the use of systemic antibiotics may published report by Schwartz-Arad and coworkers28 have prevented the negative impact of bacterial colo- of increased failure rate for IIP in men compared to nization in the healing site. The fact that all patients women, although that study evaluated a small num- included in this study were treated for their periodon- ber of implants and showed a much higher overall tal disease prior to or in conjunction with their failure rate than the current article.
implant treatment would present a population with a The findings that there was no significant differ- reduced risk for bacterial contamination from ongo- ence in failure rate associated with any single med- ing disease. The results of the present study are in ication or combination of medications taken by agreement with previous findings that rate of implant patients who received IIP and that no medical condi- failure was not correlated with age.50,51 tion was associated with a statistically significant dif- Volume 21, Number 1, 2006 COPYRIGHT 2005 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.
Froum.qxd 1/23/06 10:57 AM Page 77 ference in implant failure are of interest. Some have other failures occurred because of implants that were questioned the effect of osteoporosis and medica- immediately restored with nonoccluding provisional tions used to treat osteoporosis on implant sur- vival.52–55 The present study demonstrated no differ- Ten of the 13 implant failures that occurred in the ence in immediate implant survival related to the maxillary molar area were due to nonintegration.
taking of bisphosphonates or a reported condition of Nine of these were placed into bone augmented osteoporosis. In fact, only 2 of the 75 implants placed with 2 lateral window and 7 internal sinus lift proce- patients with a history of osteoporosis failed (n = 34).
dures. In a study by Schwartz-Arad and colleagues27 The 24 patients that were taking Fosamax (Merck, the cumulative survival rate (CSR) of all implants in West Point, PA) experienced no implant failures.
the study was 92%. The 5-year CSR was 90% in all An important part of the technique used in the areas of the maxilla but only 72% in the posterior present study was the use of a bioabsorbable mem- maxilla.27 In the present study the high survival rate brane barrier over which no attempt was made to of immediately placed implants in the maxillary achieve primary closure. The use of penicillin as a anterior area may have been related to the easier postsurgical antibiotic with these bioabsorbable bar- access in this area for bone graft and membrane riers may have decreased bacterial colonization, thus placement, along with more effective oral hygiene reducing infection postsurgery. There was a signifi- for the patient.
cant relationship between implant failure caused by Several studies have documented high survival infection and an inability to use postsurgical peni- rates for conventionally placed implants in patients cillin (P < .001). Dahlin56 reported better membrane with different types of periodontal disease.60–62 In the tolerance and less infection in patients able to take present study implants replacing teeth that were penicillin as opposed to 1 patient that had to be extracted for periodontal reasons were 2.3 times placed on erythromycin. All patients in the present more likely to fail than implants replacing teeth study who described no penicillin allergy were pre- extracted for nonperiodontal reasons. These results scribed amoxicillin starting 2 days prior to the proce- are in agreement with a previous study and demon- dure, and continued on the antibiotic for 10 days strate significantly lower survival of implants when postsurgery. Although some controversy57–59 exists placed in sites from which periodontally involved relative to the use of postsurgical antibiotics, the pro- teeth were removed.63 In patients in whom teeth tocol applied in this study used antibiotics for all were lost for periodontal reasons, the disease may patients following IIP. In the present study 30 implant have decreased the available bone following tooth failures were attributed to infection. Sixteen of the 30 extraction or resulted in the necessity to place the patients who had implant failure due to infection implant with a more exposed surface to achieve were penicillin sensitive. Five additional "infection" ideal prosthetic position. Both of these situations failures were caused by infection of an adjacent may have resulted in a greater implant failure rate.
tooth. Three of 5 of these patients were penicillin This question warrants further research.
sensitive. It is doubtful that the difference in implant The flap closure technique used in the present success seen in penicillin-allergic patients was study, with no attempt at primary closure, did not caused by a biologic difference in these patients that compromise the location of the vestibule and pre- led to a greater implant failure rate. It is more likely served the keratinized tissue at the site of the that penicillin is a more effective antibiotic for implant. However, this approach was frequently asso- implant survival than the alternative antibiotics ciated with membranes that were exposed to the given to these patients.
oral environment. Although other authors describe In the present study, a statistically significant differ- the need for primary flap closure, a literature review ence in failure rates was associated with placement in concluded that survival of implants was not depen- different locations in the maxilla and mandible. Failure dent on primary closure.21 In the present study the rates were lowest in the maxillary premolars, canines, antimicrobial regimen may have avoided the and incisors (2.81%, 2.07%, and 2.13%, respectively).
reported detrimental effects of membrane exposure.
Failure rates were highest in the mandibular incisor Considering the high clinical sur vival rates and maxillary molar areas (7.69% and 6.44%, respec- observed in this and other studies, the immediately tively). The higher failure rates in the mandibular ante- placed implant should be considered a predictable rior area may be related to overheating of the bone protocol. The fact that the survival rate in the present when long implants, 15 to 18 mm, were placed (type study showed significant differences with regard to 1). Ten of the 14 failures occurred before 2000, when gender, implant location, and implant surfaces longer implants were routinely used. Nine of the 14 should be viewed in the context of clinical signifi- failed implants were lost because of infection, and 2 cance, as survival was high even in the higher-risk The International Journal of Oral & Maxillofacial Implants COPYRIGHT 2005 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.
Froum.qxd 1/23/06 10:57 AM Page 78 groups. Patient selection, esthetic considerations, and inability to use penicillin, as well as the reasonfor tooth loss, should be considered in deciding 1. Adell R, Lekholm U, Rockler B, Brånemark P-I. A 15-year study whether or not to utilize an immediate or delayed of osseointegrated implants in the treatment of the edentu-lous jaw. Int J Oral Surg 1981;10:387–416.
implant approach.
2. Albrektsson T, Dahl E, Enbonm I, et al. Osseointegrated oral implants. A Swedish multicenter study of 8,139 consecutivelyinserted Nobelpharma implants. J Periodontol 3. Adell R, Ericksson B, Lekholm U, Brånemark P-I, Jemt T. A long- term follow-up study of osseointegrated implants in the treat- Based upon a retrospective chart review of patients ment of the totally edentulous jaw. Int J Oral Maxillofac receiving 1,925 endosseous implants placed on the day of natural tooth extraction: 4. van Steenberghe D. A retrospective multicenter evaluation of the survival rate osseointegrated implants supporting fixed • Overall implant survival rate was 96%, with 71 partial prosthesis in the treatment of partial edentulism. JProsthet Dent 1989;61:217–222.
implants failing to achieve osseointegration and 6 5. Jemt T, Lekholm U, Tagnar A. Osseointegrated implants in the implants failing to maintain integration.
treatment of partially edentulous patients: A preliminary • Rough-surface implants survived at a significantly study on 876 consecutive placed implants. Int J Oral Maxillo- higher rate (97.7%) than did machined implants fac Implants 1989;4:211–218.
(95.4%) (P = .02).
6. Jemt T, Lekholm U. Oral implant treatment in posterior par- tially edentulous jaws: A five-year follow follow-up report. Int J • There was no significant difference in implant fail- Oral Maxillofac Implants 1993;8:635–640.
ure rate between smokers and nonsmokers 7. McGlumphy EA, Peterson LJ, Larsen PE, Jeffcoat MK. Prospec- (P = .342).
tive of 429 hydroxyapatite-coated cylindric Omniloc implants • Men were 1.65 times more likely to develop placed in 121 patients. Int J Oral Maxillofac Implants implant failures than women (P = .0314).
8. Buser D, Mericske-Stern R, Bernard JP, et al. Long-term evalua- • Patients unable to take postsurgical penicillin tion of non-submerged ITI implants. Part 1: 8-year life table were 3.34 times more likely to have implant failure analysis of a prospective multicenter study with 2359 than those who used postsurgical penicillin implants. Clin Oral Implants Res 1997;8:161–172.
(P < .001).
9. Merickse-Stern R, Aerni D, Geering AH, Buser D. Long-term • Implants placed after tooth extraction due to evaluation of non-submerged hollow cylinder implants. Clini-cal and radiographic results. Clin Oral Implants Res periodontal disease were 2.3 times more likely to experience failure than implants placed after 10. Brånemark P-I, Zarb G, Albrektsson T. Tissue-Integrated Pros- tooth extraction unrelated to periodontal disease theses: Osseointegration in Clinical Dentistry. Chicago: Quin- (P < .001).
tessence, 1985.
• No significant change in implant failure rate was 11. Carlsson GE, Persson G. Morphologic changes of the mandible after extraction and wearing of the denture. Odontol Rev associated with any medical condition of patients included in this study.
12. Atwood D. Post extraction changes in the adult mandible as illustrated by microradiographs of midsagittal section andserial cephalometric roentgenograms. J Prosthet Dent 13. Lekovic V, Kenney EB, Weinlaender M, et al. A bone regenera- tive approach to alveolar ridge maintenance following tooth The authors would like to acknowledge the encouragement and extraction. Report of 10 cases. J Periodontol 1997;68:563–570.
support given by Dr Steven E. Eckert in the formulation of study 14. Lekovic V, Camargo PM, Kokkevold PR, et al. Preservation of and preparation of the manuscript. The authors would also like to alveolar bone in extraction sockets using bioabsorbable thank the staff members who spent countless hours checking membranes. J Periodontol 1998;69:1044–1049.
and rechecking the database. A special thanks to the restorative 15. Iasella JM, Greenwell H, Miller RL, et al. Ridge preservation with dentists who researched placement dates and follow-up care of freeze-dried bone allograft and a collagen membrane com- the patients in the study. pared to extraction alone for implant site development: A The authors have been involved with research on many of the clinical and histologic study in humans. J Periodontol materials mentioned in this review. The authors have no financial relationships with any commercial firms that manufacture or dis- 16. Shanaman RH. The use of guided tissue regeneration to facili- tribute these materials. tate ideal prosthetic placement of implants. Int J PeriodonticsRestorative Dent 1992;124:256–265.
17. Denissen HW, Kalk W, Veldhuis HA, Van Wass MA. Anatomic consideration for preventive implantation. Int J Oral Maxillo-fac Implants 1993;82:191–196.
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NATURE Vol 465 20 May 2010 parasites (Toxoplasma, Leishmania and active compounds — and an earlier, partial y These reports1,2 offer tremendous opportunities trypano somes) and on replicating human cel described set8 identified in a high-throughput to develop the next generation of antimalarial lines, and found that most of the compounds screen against P. falciparum — should be a first drugs. They also sound a call for the academic

August /September 2006 – Issue No. 22 The New Zealand Fire Service Magazine Reaction August/September 2006 Issue No. 22 Fire & Rescue is the flagship publication of the New Zealand Fire Service. It is produced by Media, Promotions and Communications, National Headquarters, Level 9, 80 The Terrace, Wellington. Editor: Iain Butler