Esposito M, Worthington HV, Coulthard P

Transcription

1 Interventions for replacing missing teeth: dental implants in zygomatic bone for the rehabilitation of the severely deficient edentulous Esposito M, Worthington HV, Coulthard P This is a reprint of a Cochrane review, prepared and maintained by The Cochrane Collaboration and published in The Cochrane Library 2008, Issue 4

2 TABLE OF CONTENTS HEADER ABSTRACT PLAIN LANGUAGE SUMMARY BACKGROUND OBJECTIVES METHODS RESULTS DISCUSSION AUTHORS CONCLUSIONS ACKNOWLEDGEMENTS REFERENCES DATA AND ANALYSES APPENDICES WHAT S NEW HISTORY CONTRIBUTIONS OF AUTHORS DECLARATIONS OF INTEREST SOURCES OF SUPPORT INDEX TERMS i

3 [Intervention Review] Interventions for replacing missing teeth: dental implants in zygomatic bone for the rehabilitation of the severely deficient edentulous maxilla Marco Esposito 1,HelenVWorthington 2,PaulCoulthard 1 1 Department of Oral and Maxillofacial Surgery, School of Dentistry, The University of Manchester, Manchester, UK. 2 Cochrane Oral Health Group, MANDEC, School of Dentistry, The University of Manchester, Manchester, UK Contact address: Marco Esposito, Department of Oral and Maxillofacial Surgery, School of Dentistry, The University of Manchester, Higher Cambridge Street, Manchester, M15 6FH, UK. espositomarco@hotmail.com. marco.esposito@manchester.ac.uk. Editorial group: Cochrane Oral Health Group. Publication status and date: Edited (no change to conclusions), published in Issue 4, Review content assessed as up-to-date: 16 August Citation: Esposito M, Worthington HV, Coulthard P. Interventions for replacing missing teeth: dental implants in zygomatic bone for the rehabilitation of the severely deficient edentulous maxilla. Cochrane Database of Systematic Reviews 2005, Issue 4. Art. No.: CD DOI: / CD pub2. Background ABSTRACT Dental implants are used for replacing missing teeth. Placing dental implants is limited by the presence of adequate bone volume permitting their anchorage. Several bone augmentation procedures have been developed to solve this problem. Zygomatic implants are long screw-shaped implants developed as a partial or complete alternative to bone augmentation procedures for the severely atrophic maxilla. One to three zygomatic implants can be inserted through the posterior alveolar crest and maxillary sinus to engage the body of the zygomatic bone. A couple of conventional dental implants are also needed in the frontal region of the maxilla to stabilize the prosthesis. The potential main advantages of zygomatic implants could be that in some situations bone grafting may not be needed and a fixed denture could be fitted sooner. Another specific indication for using zygomatic implants could be the need of maxillary reconstruction after maxillectomy in cancer patients. Objectives To test the hypothesis of no difference in outcomes between zygomatic implants with and without bone augmenting procedures in comparison with conventional dental implants in augmented bone for severely resorbed maxillae. Search strategy We searched the Cochrane Oral Health Group s Trial Register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE. We handsearched several dental journals. No language restrictions were applied. Personal contacts and all known zygomatic implant manufacturers were contacted to identify unpublished trials. Most recent search: May Selection criteria Randomised controlled clinical trials (RCTs) including patients with severely resorbed maxillae who could not be rehabilitated with conventional dental implants, treated with zygomatic implants with and without bone grafts versus patients treated with conventional dental implants in conjunction with bone augmentation procedures having a follow up of at least 1 year. Outcome measures considered were: prosthesis and implant failures, side effects, patient satisfaction and cost effectiveness. 1

4 Data collection and analysis Screening of eligible studies, assessment of the methodological quality of trials and data extraction were to be conducted in duplicate and independently by two authors. Results were to be expressed as random-effects models using weighted mean differences for continuous outcomes and risk ratio for dichotomous outcomes with 95% confidence interval. Heterogeneity was to be investigated including both clinical and methodological factors. Main results No RCTs or controlled clinical trials (CCTs) were identified. Authors conclusions There is the need for RCTs in this area to assess whether zygomatic implants offer some advantages over alternative bone augmentation techniques for treating atrophic maxillae. PLAIN LANGUAGE SUMMARY Interventions for replacing missing teeth: dental implants in zygomatic bone for the rehabilitation of the severely deficient edentulous maxilla There are no comparative trials evaluating the effectiveness of long implants passing through the sinus and into cheekbone as an alternative to bone augmentation procedures. Sometimes there is not enough bone in the upper jaw in which to secure dental implants. Bone is sometimes taken from somewhere else in the person s body, or bone substitutes are used. An alternative approach is to place one to three long screw-shaped implants into the sinus and the cheekbone (zygomatic implants). This may mean that bone grafting is unnecessary. The review found no trials comparing the outcomes of zygomatic implants with conventional bone grafting. BACKGROUND Dental implants are now commonly used for replacing missing teeth in various clinical situations. Dental implants are surgically inserted in the jawbones. However, the possibility of placing dental implants is limited by the presence of adequate bone volume permitting their anchorage. In many clinical situations, in particular for edentulous patients with heavily resorbed jawbones and patients who underwent traumatic bone loss or resective surgery for oral cancer, there is insufficient bone to allow implant placement. Unfortunately, these people have more problems to adapt to conventional dentures, since dentures cannot be easily stabilized in the mouth due to lack of retention and therefore these people have serious difficulties in eating and speaking. In order to solve this problem several bone augmentation procedures have been developed. In principle the missing bone is taken from a donor site (for example the iliac crest), transplanted where needed and then implants are placed. Sometimes, major bone grafting operations have to be undertaken under general anaesthesia requiring patients to be hospitalised for a few days. Some degree of morbidity related to the donor site must be expected and two to three surgical interventions may be needed before the implants can be functionally used. Sometimes patients have to wait more than 1 year before a denture can be fixed to the implants and the total cost of the treatment is high. More information about the effectiveness of various bone augmentation procedures can be found elsewhere (Coulthard 2003). At the beginning of the 1990s a long screw-shaped implant was developed by Professor P-I Brånemark as an alternative to bone augmentation procedures: the zygomatic implant (Stevenson 2000). Zygomatic implants are generally inserted through the alveolar crest and maxillary sinus to engage the body of the zygomatic bone (cheekbone). The operation requires an experienced and skilful surgeon and the opening of the maxillary sinus to properly visu- 2

5 alize the correct placement of the implant. Implants are generally placed as posteriorly as possible (generally near the position of the second premolars) close to the alveolar crest, but they tend to be located more palatally than the actual position of the teeth. One to three zygomatic implants can be used on each side of the maxilla. The operation requires general anaesthesia or conscious sedation and local anaesthesia for pain control. Generally implants are left to heal covered by the oral mucosa for up to 6 months, though case reports of successfully immediately loaded zygomatic implants are known. Their potential advantages are that alternative bone augmentation procedures may not be needed and patients may be fitted with a fixed denture sooner. It is believed that two zygomatic implants are not sufficient to hold a fixed denture so they need some extra conventional implants (at least two) in the anterior portion of the maxilla (Bedrossian 2001). This could only be accomplished if there is sufficient bone in the anterior portion of the maxilla, otherwise bone grafting is still needed. An alternative is to place two or three zygomatic implants in each zygoma. Indications for zygomatic implants could be the following. OBJECTIVES To test the null hypothesis of no difference for each harmful and beneficial effect between zygomatic implants with and without bone augmenting procedures in comparison with conventional dental implants in augmented bone for severely resorbed maxillae, against the alternative hypothesis of a difference. The three different potential indications were to be evaluated separately. (1) Zygomatic implants as a complete alternative to any bone augmentation procedures to severely atrophic maxillae. (2) Zygomatic implants as a partial alternative to any bone augmentation procedures to severely atrophic maxillae; i.e. some augmentation procedure is still required in the frontal portion of the maxilla. (3) Zygomatic implants for retaining obturator in maxillectomy cases. Treatment of severely atrophic maxillae without using any bone augmentation procedure. There may be two different clinical situations: (a) there is enough bone in the frontal maxillary region to allow the placement of at least two short implants; or (b) there is not enough bone in the frontal regions and two to three zygomatic implants are used in each upper quadrant to hold a fixed prosthesis without using any conventional dental implants. Treatment of severely atrophic posterior maxillae avoiding sinus lifting procedures, however bone augmentation procedures are still required in the frontal maxilla. Maxillary reconstruction after partial or total maxillectomy. Zygomatic implants can be used to fix maxillary obturators as an alternative to not implant retained obturators, local and regional flaps, and microvascular free flaps (Schmidt 2004). It would be beneficial to both patients and society to determine whether zygomatic implants offer a more effective and safe alternative to bone augmentation procedures. At the moment three companies are selling threaded titanium zygomatic implants: Nobel Biocare AB (Göteborg, Sweden) the Zygoma Implant. Brånemark Integration AB (Göteborg, Sweden) the Z Fixture. Southern Implants (Irene, South Africa) the Zygomatic Implant, a similar design to the Nobel Biocare implant. METHODS Criteria for considering studies for this review Types of studies Randomised controlled clinical trials (RCTs) with a parallel group or split-mouth design and preference randomised controlled clinical trials. Types of participants Patients who have an atrophic maxilla that cannot be rehabilitated with conventional dental implants due to lack of bone, including patients subjected to cancer ablation surgery and irradiation therapy. Patients can be partially or totally edentulous. Types of interventions Zygomatic implants with or without bone grafts versus conventional dental implants in augmented maxillae with a follow up of at least 1 year. Types of outcome measures Prosthesis could not be placed or loss of prosthesis secondary to implant failure. Implant failures defined as mobile implants, removal of stable implants dictated by progressive marginal bone loss or 3

6 infection, implant fractures, implants which were left sleeping due to wrong alignment. Side effects. Patient satisfaction and if possible preference. Cost effectiveness. Search methods for identification of studies For the identification of studies included or considered for this review we developed detailed search strategies for each database to be searched. These were based on the search strategy developed for MEDLINE (OVID) but revised appropriately for each database. The search strategy combined a sensitive search strategy for randomised controlled clinical trials (RCTs) (as published in Appendix 5c in the Cochrane Handbook for Systematic Reviews of Interventions 4.2.5). The search strategy used a combination of controlled vocabulary and free text terms as illustrated in Appendix 1. Searched databases The Cochrane Oral Health Group s Trial Register (to May 2005) The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 2, 2005) MEDLINE (1966 to May 2005) EMBASE (1980 to May 2005). The last electronic search was done on 16 May Language Non-English papers were to be included. Unpublished studies We wrote to all the authors of the identified RCTs, we checked the bibliographies of all identified RCTs and relevant review articles, and we used personal contacts in an attempt to identify unpublished or ongoing RCTs. In the first version of this review we also wrote to more than 55 oral implant manufacturers and we requested information on trials through an Internet discussion group (implantology@yahoogroups.com), however we discontinued this due to poor yield. Handsearching Details of the journals being handsearched by the Cochrane Oral Health Group s ongoing programme are given on the website: The following journals have been identified as being potentially important to be handsearched for this review: British Journal of Oral and Maxillofacial Surgery, Clinical Implant Dentistry and Related Research, Clinical Oral Implants Research, European Journal of Oral Implantology, Implant Dentistry, International Journal of Oral and Maxillofacial Implants, International Journal of Oral and Maxillofacial Surgery, International Journal of Periodontics and Restorative Dentistry, International Journal of Prosthodontics, Journal of Clinical Periodontology, Journal of Dental Research, Journal of Oral Implantology, Journal of Oral and Maxillofacial Surgery, Journal of Periodontology, Journal of Prosthetic Dentistry. Where these have not already been searched as part of the Cochrane Journal Handsearching Programme, the journals were handsearched by one review author up to the month in which the last electronic search was undertaken. Data collection and analysis The titles and abstracts (when available) of all reports identified by the search strategy were scanned independently by two authors. For studies appearing to meet the inclusion criteria, or for which there were insufficient data in the title and abstract to make a clear decision, the full report was obtained and assessed independently by two authors to establish whether the studies met the inclusion criteria or not. Disagreements were to be resolved by discussion. Where resolution was not possible, a third author was to be consulted. All studies meeting the inclusion criteria were to undergo quality assessment and data were to be extracted. Studies rejected at this or subsequent stages were to be recorded in the table of excluded studies, and reasons for exclusion recorded. Quality assessment The quality assessment of the included trials was to be undertaken independently and in duplicate by two authors based on what was written in the articles. Three main quality criteria were to be examined. (1) Allocation concealment, recorded as: (A) Adequate (B) Unclear (C) Inadequate. (2) Independent assessor as: (A) Yes (B) No (C) Unclear. (3) Completeness of follow up (is there a clear explanation for withdrawals and drop outs in each treatment group?) assessed as: (A) Yes. In the case that clear explanations for drop outs are given, a further subjective evaluation of the risk of bias assessing the reasons for the drop out has to be made. (B) No. After taking into account the additional information provided by the authors of the trials, studies were to be grouped into the following categories. (A) Low risk of bias (plausible bias unlikely to seriously alter the results) if all criteria were met. 4

7 (B) Moderate risk of bias (plausible bias that raises some doubt about the results) if one or more criteria were partly met. (C) High risk of bias (plausible bias that seriously weakens confidence in the results) if one or more criteria were not met as described in the Cochrane Handbook for Systematic Reviews of Interventions Data extraction Data were to be extracted by two authors independently using specially designed data extraction forms. Any disagreement was to be discussed and a third author consulted where necessary. Authors were to be contacted for clarification or missing information. Data were to be excluded until further clarification was available if agreement could not be reached. For each trial the following data were to be recorded: Year of publication, country of origin, setting and source of study funding. Details of the participants including demographic characteristics and criteria for inclusion. Details on the type of intervention. Details of the outcomes reported, including method of assessment and time intervals. Data synthesis For dichotomous outcomes, the estimate of effect of an intervention was to be expressed as risk ratios together with 95% confidence intervals. For continuous outcomes, mean differences and 95% confidence intervals were to be used to summarise the data for each trial. Clinical heterogeneity was to be assessed by examining the types of participants, interventions and outcomes in each study with a planned subgroup analysis for various bone grafting techniques and for different groups of patients (patients with severely resorbed maxillae versus cancer patients subjected to irradiation therapy). Meta-analyses were to be conducted only with studies of similar comparisons reporting the same outcome measures. Risk ratios were to be combined for dichotomous data, and weighted mean differences for continuous data, using a random-effects model. The significance of any discrepancies in the estimates of the treatment effects from the different trials was to be assessed by means of Cochran s test for heterogeneity and quantified by I 2 statistic. Any heterogeneity was to be investigated. Sensitivity analyses were to be undertaken to examine the effect of concealed randomisation and outcome assessor being independent on the assessment of the overall estimates of effect. In addition, the effect of including unpublished literature on the review s findings was to be examined. RESULTS Description of studies No published or ongoing randomised controlled clinical trials or controlled clinical trials were identified. Risk of bias in included studies No published or ongoing randomised controlled clinical trials or controlled clinical trials were identified. Effects of interventions No published or ongoing randomised controlled clinical trials or controlled clinical trials were identified. DISCUSSION It is somewhat disappointing to find no randomised controlled clinical trials (RCTs) or controlled clinical trials (CCTs) comparing zygomatic implants with bone augmentation techniques for the rehabilitation of the severely atrophic maxilla. Several published retrospective (Bedrossian 2002; Brånemark 2004; Landes 2005; Malevez 2004; Nakai 2003; Schmidt 2004; Stevenson 2000)and one prospective (Hirsch 2004) case series studies have recently become available. We are also aware of one additional ongoing case series study including additional 40 patients with a 2-year follow up from the clinic in Jönköping, Sweden. In order to help trialists in this area we thought that it would be helpful to present a brief summary for these studies so that readers can appreciate some of the issues for the future design of RCTs. This is not presented as part of the evidence base for this review which was restricted to RCTs. The most informative and better described trial is a long-term retrospective study (Brånemark 2004) including the first 28 consecutively patients treated at the Brånemark Osseointegration Center in Göteborg, Sweden, with zygomatic implants placed under general anaesthesia. A total of 52 zygomatic and 106 conventional dental implants were placed. Bone grafts were deemed necessary in 17 patients. Most patients experienced extensive swelling and bruising postoperatively that normalised in 10 to 14 days. Patients stayed in hospital for 1 to 6 days. Patients who did not have bone grafting left the hospital the day after the operation. All patients were followed up for at least 5 years, and nine patients were followed up to 10 years. Three patients died during the follow-up period. One fixed prosthesis failed and had to be converted into a denture. Three zygomatic implants failed (6%) in three patients, two at abutment connection and one after 6 years of function. Twenty-nine (27%) conventional dental implants failed over the entire follow-up period in 13 patients. Four patients (14%) affected by recurrent sinusitis had to be treated with an inferior 5

8 meatal antrostomy, to create a permanent opening of the maxillary sinus to the nasal cavity. In two of the patients affected by sinusitis, suppuration at the palatal entrance was observed after 6 and 9 years of follow up. This may suggest that oral bacteria reached the sinus following the resorption of the peri-implant alveolar bone. One potential problem may therefore be the development of sinus pathology when bone, already atrophic, is subjected to further bone loss such as by perimplantitis. This problem seems to be confirmed by the preliminary unpublished results of the ongoing trial in Jönköping. Other four patients (14%) displayed radiographic sign of sinusitis with no clinical signs and treatment was not considered necessary. Zygomatic implants were also used to stabilize obturators for reconstructing extensive maxillary defects after maxillectomy in nine patients (Schmidt 2004). Five patients had radiation therapy, four of which 2 weeks after implant placement. Twenty-eight zygomatic and 10 conventional implants were placed under general anaesthesia. Six zygomatic (21%) and three conventional implants (30%) were found to be not osseointegrated at abutment connection in three patients. Five patients were successfully reconstructed with maxillary obturators in function for 2 to 3 years; two patients were in the phase of osseointegration and therefore the fate of their implants could not be evaluated, whereas two patients died from malignancy. Anothertrialevaluatedzygomatic implantsusedtostabilize obturators in patients with extensive maxillary defects who could not or did not want to undergo major reconstruction surgery with bone grafts (Landes 2005). Twelve patients who received 28 zygomatic implants and 23 conventional dental implants were included in the trial and followed up 14 to 53 months. Six patients received preoperative chemotherapy and five patients were postoperatively irradiated. All operations were conducted under general anaesthesia. Quality of life was measured with a validated questionnaire. A certain number of zygomatic implants failed, but it is not clear exactly how many, possibly 18% to 29%. Chronic infection around the zygomatic implants seemed to be the most common reason for failure. One patient refused to undergo the abutment connection operation and therefore the implants could not be used to hold the obturator, whereas another patient loss his prosthesis due to multiple implant failures. Another patient lost the prosthesis due to tumour recurrence. Two of the 10 patients interviewed did not return the questionnaires. All eight patients reported an improved general quality of life, however the half of the patients reported worsened (3) or identical (1) health-related quality of life when compared to the situation before treatment. Considering that two patients did not return the questionnaires, the outcome from a patient perspective, may not be considered exceptional. On the other hand we have to consider that these patients suffered from severe mutilations, therefore full satisfaction may be hard to obtain. In a retrospective trial conducted in Belgium (Malevez 2004) 55 consecutively partially or totally edentulous patients received 103 zygomatic and 194 conventional dental implants. Operations were conducted under general anaesthesia and it was reported that with exception for the first two patients, all received corticosteroids to avoid the important swelling of the lip and the face. Bone grafts were deemed necessary in seven patients. Implants were followed for 6 to 48 months. No zygomatic implant failed, whereas 16 conventional implants (9%) failed in seven patients. The complications reported were a severe sinus infection during the healing period which was successfully treated with antibiotics; five patients had sinusitis that, however, could not be associated with the zygoma implants. One patient had a variety of several complaints due to psychological problems, one patient had problems with oral hygiene control, and one patient had aesthetic problems. The authors also reported that all zygomatic implants in this series are still in function, without complications, and with no signs of pain, infection or any pathology. For three patients with implant failures it was necessary to go from a fixed prosthesis to a removable prosthesis. Another retrospective trial including 22 selected patients ( Bedrossian 2002), treated under intravenous sedation in a private practice in USA, is of limited clinical value. Forty-four zygomatic and 80 conventional implants were placed and followed up to 34 months. Bone grafts were deemed necessary in four patients. Implants were rigidly fixed with a screwed metal bar. No zygomatic implant was considered failed, whereas in five patients seven conventional implants failed (9%). No success criteria, complications or precise follow up were reported. The only prospective trial (Hirsch 2004) originally included 76 patients consecutively treated with 145 zygomatic implants at 16 different centres with a follow up of 1 year in function. After 1year66patientswith124zygomaticimplantswereevaluated. The reasons for exclusion of 11 patients were unclear: at least six patients were withdrawn from the study for unexplained reasons and a couple of patients had not passed the 1-year follow up but were included anyway in the trial, three zygomatic implants were left uncovered whereas three zygomatic implants failed into two patients at abutment connection. Such deficiencies in reporting the reasons for patient exclusion suggest that an under-reporting of problems might have occurred (attrition bias). Sixty-four fixed bridges were successful whereas two fixed bridges had to be converted into overdentures. One planned fixed bridge could not be placed due to the failures of two zygomatic implants at abutment connection. Excessive intraoperatively bleeding was reported in three patients, one of which developed a postoperative infection. Pain and/or impaired nerve function was reported in six patients. After 1 year symptoms persisted in three patients. Five patients developed a fistula, and three patients (4%) experienced clinical symptoms from the sinuses (night pain, pain in bad weather and blockage of the sinus). While the scarcity of long-term clinical results can be explained 6

9 by the fact that zygomatic implants are a relatively new procedure, it is rather discouraging to observe that we were not able to identify even one ongoing comparative clinical trial testing the efficacy of zygomatic implants in comparison with traditional bone augmentation procedures. This may be not totally surprising if one considers that in another Cochrane review on the efficacy of various bone augmentation procedures (Coulthard 2003) only seven RCTs were included despite the large body of literature published in the last 30 years on this topic. The placement of zygomatic implants requires very experienced surgeons, is not risk-free since delicate anatomic structures such as the orbita may be involved, and may not be sufficient to avoid bone augmentation procedures. The main complication which seems to occur with zygomatic implants is sinusitis which may develop several years after their placement ( Brånemark 2004). In case of complications, it is rather difficult to remove zygomatic implants. In addition there is growing evidence suggesting that sinus lift procedures can be highly successful with minimal complications and patient discomfort (Hallman 2002). Therefore, we foresee a great need to conduct high quality RCTs to investigate the potential advantages of zygomatic implants before recommending the routine use of this procedure. AUTHORS Implications for practice CONCLUSIONS No published or ongoing randomised controlled clinical trials (RCTs) or even controlled clinical trials (CCTs) were identified so it is not possible to give reliable evidence-based advice to potential users with respect to the efficacy of zygomatic implants as an alternative to various augmentation procedures for severely deficient maxillae. It seems that zygomatic implants yield high survival rates, however complications are common and may increase over time. Until convincing evidence is available, we do not encourage aroutineuseofzygomaticimplants. Implications for research Even recognizing the fact that zygomatic implants are a relatively new treatment modality, it is disappointing that not even one ongoing RCT, comparing zygomatic implants with any alternative augmentation techniques, could be identified. It is therefore suggested that multicentre, properly designed RCTs should be implemented in this area, before any recommendation on the use of zygomatic implants could be given. In order to exploit the maximum potential advantages of zygomatic implants, it may be worth to assess their performance when immediately or early loaded in order to shorten the treatment time for the patients. Complications with zygomatic implants need also to be thoroughly assessed and compared with those occurring with alternative bone augmentation procedures. It is also important that long follow-up periods are considered (definitely more than 5 years), since some complications such as sinusitis seem to develop at a later stage. The research agenda should give priority to the evaluation of zygomatic implants as a complete alternative to any bone augmentation procedure in the severely atrophic maxilla and as retainer of obturators in maxillectomy cases. ACKNOWLEDGEMENTS We wish to thank Sylvia Bickley (Cochrane Oral Health Group) for her assistance with literature searching, Emma Tavender and Luisa Fernandez (Cochrane Oral Health Group) for their help with the preparation of this review. We would also like to thank the following referees: Bertil Friberg, Anne-Marie Glenny, Jayne EHarrison,LeeHooper,IanNeedlemanandGöranWidmark. REFERENCES Additional references Bedrossian 2001 Bedrossian E, Stumpel LJ III. Immediate stabilization at stage II of zygomatic implants: rationale and technique. Journal of Prosthetic Dentistry 2001;86(1):10 4. Bedrossian 2002 Bedrossian E, Stumpel L III, Beckely ML, Indersano T. The zygomatic implant: preliminary data on treatment of severely resorbed maxillae. A clinical report. The International Journal of Oral and Maxillofacial Implants 2002;17(6): Brånemark 2004 Brånemark PI, Gröndahl K, Öhrnell LO, Nilsson P, Petruson B, Svensson B, et al.zygoma fixture in the management of advanced atrophy of the maxilla: technique and long-term results. Scandinavian Journal of Plastic and Reconstructive Surgery 2004;38 (2): Coulthard 2003 Coulthard P, Esposito M, Jokstad A, Worthington HV. Interventions for replacing missing teeth: bone augmentation techniques for dental implant treatment. Cochrane Database of Systematic Reviews 2003, Issue 3. [Art. No.: CD DOI: / CD003607] Hallman 2002 Hallman M, Sennerby L, Lundgren S. A clinical and histologic evaluation of implant integration in the posterior maxilla after sinus floor augmentation with autogenous bone, bovine hydroxyapatite, or a 20:80 mixture. The International Journal of Oral and Maxillofacial Implants 2002;17(5):

10 Hirsch 2004 Hirsch JM, Öhrnell LO, Henry PJ, Andreasson L, Brånemark PI, Chiapasco M, et al.a clinical evaluation of the Zygoma fixture: one year of follow-up at 16 clinics. Journal of Oral and Maxillofacial Surgery 2004;62(9 Suppl 2):22 9. Landes 2005 Landes CA. Zygoma implant-supported midfacial prosthetic rehabilitation: a 4-year follow-up study including assessment of quality of life. Clinical Oral Implants Research 2005;16(3): Malevez 2004 Malevez C, Abarca M, Durdu F, Daelemans P. Clinical outcome of 103 consecutive zygomatic implants: a 6-48 months follow-up study. Clinical Oral Implants Research 2004;15(1): Nakai 2003 Nakai H, Okazaki Y, Ueda M. Clinical application of zygomatic implants for rehabilitation of the severely resorbed maxilla: a clinical report. The International Journal of Oral and Maxillofacial Implants 2003;18(4): Schmidt 2004 Schmidt BL, Pogrel MA, Young CW, Sharma A. Reconstruction of extensive maxillary defects using zygomaticus implants. Journal of Oral and Maxillofacial Surgery 2004;62(9 Suppl 2):82 9. Stevenson 2000 Stevenson AR, Austin BW. Zygomatic fixtures - the Sydney experience. Annales of the Royal Australasian College of Dental Surgeons 2000;15: Indicates the major publication for the study 8

11 DATA AND ANALYSES This review has no analyses. APPENDICES Appendix 1. MEDLINE (OVID) search strategy #1 randomised controlled trial.pt. #2 controlled clinical trial.pt. #3 randomized controlled trials.sh. #4 random allocation.sh. #5 double blind method.sh. #6 single blind method.sh. #7 latin square.ti,ab. #8 crossover.ti,ab. #9 (split adj (mouth or plot)).ti,ab. #10 or/1-9 #11 (ANIMAL not HUMAN).sh. #12 10 not 11 #13 clinical trial.pt. #14 exp clinical trials/ #15 (clin$ adj25 trial$).ti,ab. #16 ((singl$ or doubl$ or trebl$ or tripl$) adj25 (blind$ or mask$)).ti,ab. #17 placebos.sh. #18 placebo$.ti,ab. #19 random$.ti,ab. #20 research design.sh. #21 or/13-20 #22 21 not 11 #23 22 not 12 #24 12 or 22 #25 exp Dental Implants/ #26 exp Dental Implantation/or dental implantation.mp. #27 exp Dental Prosthesis, Implant-Supported/ #28 ((osseointegrated adj implant$) and (dental or oral)).mp. [mp=title, abstract, registry number word, mesh subject heading] #29 dental implant$.mp. [mp=title, abstract, registry number word, mesh subject heading] #30 (implant$ adj5 dent$).mp. [mp=title, abstract, registry number word, mesh subject heading] #31 dental-implant$.mp. [mp=title, abstract, registry number word, mesh subject heading] #32 (((overdenture$ or crown$ or bridge$ or prosthesis or prostheses or restoration$) adj5 (Dental or oral)) and implant$).mp. [mp=title, abstract, registry number word, mesh subject heading] #33 implant supported dental prosthesis.mp. [mp=title, abstract, registry number word, mesh subject heading] #34 ( blade implant$ and (dental or oral)).mp. [mp=title, abstract, registry number word, mesh subject heading] #35 ((endosseous adj5 implant$) and (dental or oral)).mp. [mp=title, abstract, registry number word, mesh subject heading] #36 ((dental or oral) adj5 implant$).mp. [mp=title, abstract, registry number word, mesh subject heading] #37 ((zygoma$ OR malar$) adj6 implant$) #38 OR/25-37 #39 24 AND 38 9

12 WHAT S NEW Last assessed as up-to-date: 16 August June 2008 Amended Converted to new review format. HISTORY Protocol first published: Issue 2, 2003 Review first published: Issue 3, August 2005 New citation required but conclusions have not changed Substantive amendment. CONTRIBUTIONS OF AUTHORS Conceiving, designing and co-ordinating the review (Marco Esposito (ME)). Developing search strategies and undertaking searches (ME, Paul Coulthard (PC)). Screening search results and retrieved papers against inclusion criteria (ME, PC). Writing the review (ME). Providing general advice on the review (PC, Helen Worthington (HW)). DECLARATIONS OF INTEREST None known. SOURCES OF SUPPORT Internal sources School of Dentistry, The University of Manchester, UK. 10

13 External sources Swedish Medical Research Council (9495), Sweden. INDEX TERMS Medical Subject Headings (MeSH) Alveolar Ridge Augmentation; Dental Implants; Bone Transplantation; Dental Implantation, Endosseous; Dental Prosthesis, Implant- Supported; Jaw, Edentulous [ rehabilitation] MeSH check words Humans 11