Timing of implant placement relative to tooth extraction

Journal of Oral Rehabilitation 2008 35 (Suppl. 1); 33 43 Timing of implant placement relative to tooth extraction L. SCHROPP & F. ISIDOR Department of Prosthetic Dentistry, University of Aarhus, Aarhus C, Denmark SUMMARY In recent years, immediate or early implant placement after tooth extraction has becoming more common. The present review focuses on the clinical outcome of immediate or early implant placement. Only limited knowledge exists about most of the factors with particular significance for this treatment mode. Randomized controlled clinical studies comparing the various treatment protocols are scarce. With the background in the existing literature some conclusions can be drawn with caution. Survival rates for implants placed immediately, early, delayed, or late seem to be similar in the short perspective and amounts to approximately 95%. Successful immediate implant placement may be possible in all regions of the jaws, although replacement of molars is more challenging. Chronic infection is not an absolute contraindication for immediate implant placement. It is controversial whether immediate placement of implants may preserve the alveolar bone. Small gaps between implant surface and socket wall have a potential for spontaneous healing. No consensus exists on the need for bone augmentation in these situations. With the limited information available it may be stated that a good prognosis can be obtained following immediate early functional or non-functional loading of immediately placed implants. However, higher risk of failures seems to exist compared with a delayed, conventional approach. It is advocated that this treatment modality should be restricted to skilled well-trained teams. Data on the aesthetic outcomes following immediate early implant placement are inconclusive, but this treatment can offer high patient satisfaction with the aesthetic and functional outcomes. KEYWORDS: review, timing, implants, placement, immediate, early, delayed, extraction socket, survival, success Accepted for publication 4 November 2007 Introduction Placement of dental implants for replacing missing teeth is a well-established treatment option. According to the original protocol, it was state of the art to wait several months after tooth extraction before placement of the implants to allow alveolar bone healing (1). Along with the recommended load-free period of 3 6 months to ensure osseointegration of the implants, a long treatment period was an obvious drawback of this treatment modality. This protocol has been challenged the last decades by reducing the time between extraction of a tooth and placing and or loading of the implant. Various classifications have been suggested for the timing between tooth extraction and implant placement. This can make it difficult to compare the outcome of previous studies. In a recent systematic review, an implant placed in a fresh extraction socket was denoted an immediate implant. An implant placed in an extraction socket within 8 weeks after tooth extraction was called immediate-delayed and later placed implants were called delayed implants (2). Apart from reducing the time period and the number of surgical interventions, other advantages of immediate or early (immediate-delayed) implant placement in the extraction socket has been suggested, such as better implant survival rates, better aesthetics, maintenance of the hard and soft tissues at the extraction site, and higher patient satisfaction compared with delayed (late) placed implants. On the other hand, because of the nature of this treatment method, a higher risk of complications and failures may be expected. In 2006, Esposito et al. (2) published a systematic review of randomized controlled trials (RCT) on dental doi: 10.1111/j.1365-2842.2007.01827.x

34 L. SCHROPP & F. ISIDOR implants placed in fresh extraction sockets. On the basis of only two studies fulfilling the selection criteria, it was concluded that immediate or immediate-delayed placement of implants is a viable treatment option and may be associated with better outcomes in terms of aesthetics and patient satisfaction compared with conventionally placed implants (3 7). The authors, however, emphasized that more RCT are needed to draw definitive conclusions. This review will focus on the clinical outcome of immediate or early implant placement on the basis of the current literature and point out factors, which may have especial significance when an implant is placed in a fresh or recent extraction socket and, therefore, should be considered by the clinician in patient selection and choice of surgical and prosthetic procedures. Materials and methods Search strategy A PubMed search of English literature was conducted up to May 2007 using the terms: implants and ( immediate placement or delayed placement or early placement or delayed-immediate or extraction sockets ), immediate extraction sockets, immediate post-extraction, immediate implants. Additionally, the bibliographies of 13 previous reviews as well as articles published in 2007 for nine journals (Clinical Oral Implants Research, Clinical Implant Dentistry and Related Research, Implant Dentistry, International Journal of Oral and Maxillofacial Implants, International Journal of Periodontics and Restorative Dentistry, International Journal of Prosthodontics, Journal of Periodontics, Journal of Oral Implantology, Journal of Clinical Periodontology) were manually searched. This search failed to reveal more randomized studies than in the review of Esposito et al. (2). In consequence, a more narrative mode of review was chosen. The selection criteria were less rigorous as randomized or non-randomized clinical prospective and retrospective studies enrolling at least 10 implants placed in human subjects were included. Results The overall outcome of immediate or early implant placement Reviews of the literature show that the survival rates of immediately, early, or delayed placed implants are comparable with those of implants placed in healed alveolar bone (2, 8 12). In general, approximately 5% of implants can be expected to be lost regardless the protocol being used. It should be stressed that the follow-up period for most of the studies on immediate implants is relatively short with only few papers reporting results of >5 years of loading. Quirynen et al. (12) found that useful data on crestal bone loss (CBL) is lacking. Most studies only report on the mean peri-implant bone loss and the authors draw attention to the fact that frequency distribution on ranges of marginal bone loss would be more useful information for the clinician. It was stated that the above also applies for data on pocket depth and attachment level changes. Chen et al. (8) concluded in a review that no significant differences in radiographic crestal bone level or in probing depth at implants placed immediately, delayed, or late relative to tooth extraction were found. Benefits and risk factors associated with the immediate implant placement protocol Particular conditions exist when an implant is placed in a fresh or recent extraction alveolus compared with placement in healed bone. These can be advantageous to the treatment outcome but may also constitute risk factors. These aspects will be discussed in the following. Does immediate implant placement preserve the post-extraction alveolar bone? A prerequisite for success of intraosseous implant treatment is achievement of osseointegration (13). Furthermore, it has been shown that primary implant stability is crucial for successful osseointegration (14). To ensure primary implant stability a sufficient amount of bone of good quality is needed. Following extraction of one or more teeth, a significant reduction in vertical height and buccolingual width of the alveolar ridge takes place. The amount of the morphological changes is dependent on several patient related factors and a great variation among individuals is seen. In a recent study (15), including 46 molar or premolar extraction sites, it was demonstrated that minor vertical changes occurred following singletooth extraction while the buccolingual width of the ridge was reduced by approximately 50% during an observation period of 1 year. In the literature, it has often been stated that one of the rationales of imme-

TIMING OF IMPLANT PLACEMENT TO TOOTH EXTRACTION 35 diate implant placement is that this approach may prevent or at least minimize the loss of soft and hard tissue at the extraction site. It is clear that controversies exist on this issue. A long-term study by Denissen and Kalk (16) showed that immediately placed submerged hydroxyapatite implants contributed to the maintenance of alveolar ridge volume, and in addition Wheeler et al. (17) demonstrated in a clinical report preservation of hard and soft tissue with enhancement of the aesthetic result after immediate placement of tapered root-analog implants combined with custom healing abutments. On contrary, recent animal and clinical studies indicate that morphologic changes of the alveolar ridge cannot be prevented by the immediate placement protocol (18 23). It was shown that the buccal and lingual socket walls underwent marked resorption following implant placement and that the height of the buccal hard tissue wall was reduced (18). It is apparently of importance that the immediate implant is placed correctly in the alveolus to prevent exposure of the implant surface. It has been suggested (12) to place the implant lingually palatally in the socket, even though this at first may result in a larger gap buccally, as bone formation in the defect can be expected concurrently with resorption of the buccal bone wall. Although conflicting results exist, immediate implantation may preserve the post-extraction alveolar bone. No matter whether the implant is placed immediately or later in the alveolar bone, it is very important to extract teeth carefully to minimize bone loss. Particularly, the buccal wall of the alveolus is exposed to trauma, and damage should be avoided. Sectioning of multi-rooted teeth is recommended before removal. Does infection at the extraction site affect the outcome of immediate implant placement? Pathology of the tooth or the periodontal tissues may have an influence on the treatment success when replacing the tooth immediately after removal with an implant. Infection at the recipient site has been a matter of concern in conjunction with implant placement in the extraction alveolus and has of some authors been considered as a contraindication for using this protocol. Infection could be caused by marginal periodontitis, periapical pathology, failures of endodontic treatments and root fractures. In addition, loss of tissue because of disease may compromise the possibility of achieving primary implant stability, as well as impair the aesthetics. One RCT (3) has been published comparing in sites with periapical infection, 25 single implants placed immediately after tooth extraction and 25 implants placed after 3 months of healing. Two immediate implants were lost, but no statistically differences in failure rates, mean Implant Stability Quotient (ISQ) values, gingival aesthetics, radiographic bone resorption and periapical microbiologic characteristics were seen between the groups. The authors concluded that immediate implant placement in chronic periapical lesions may be indicated. Two animal studies demonstrated that implants placed in infected sites were not at risk (24, 25), whereas the success of immediate implants replacing teeth with a history of marginal periodontitis was slightly lower in humans (26, 27). More studies are needed to elucidate the complex of problems associated with residual infection at the implant recipient site. Therefore, on basis of the existing information, it is not valid to recommend or caution not to do immediate implant placement in an extraction site with inflammation. On contrary, it seems reasonable to recommend thorough debridement of the chronically infected extraction socket before implant placement. Furthermore, it seems sensible to use antibiotics in medically compromised patients. As the use of antibiotics may have some adverse effects, such as emergence and accumulation of bacterial drug resistance and various other side effects, it is important to restrict the use in cases where necessary. Does a gap between the implant and the socket wall affect the outcome of immediate implant placement? When an implant is placed in a fresh or recent extraction alveolus a gap between the implant surface and the bone walls of the socket may occur. The presence or size of the gap is both influenced by the configuration of the alveolus and by the design and width of the implant. The socket configuration is mainly determined by the anatomy of the extracted tooth; however, pathology of the tooth or in its vicinity before extraction, as well as trauma in relation to removal of the tooth may cause damage to the bone walls. This may in turn alter the original anatomy and in severe cases leave the socket in absence of one or more bone walls with formation of a dehiscence defect. It has been a matter of debate whether such gaps or dehiscence defects necessitated performance of bone augmentation procedures or whether they could be left

36 L. SCHROPP & F. ISIDOR for spontaneous healing. Studies have demonstrated that infrabony defects were fully or partly resolved without intervention of augmentation treatments. In 46 patients treated with immediate implants total bone formation occurred in the sockets without the use of membranes or bone grafting (26). In a randomized study comparing immediate and delayed implant placement a high potential for spontaneous healing in threewall infrabony defects was demonstrated for both protocols (4). In an animal study, it was shown that a circumferential gap of 1 1Æ25 mm lateral to an implant may heal with new bone and that placement of a membrane did not improve the healing (28). In a RCT (29) comparing maxillary single implants placed in extraction sockets in patients treated with particulated autogenous bone with patients not subjected to any augmentation procedure, substantial bone gain was obtained in both groups, and no statistically significant differences were found. In the case that immediate placement results in a fenestrated implant or a dehiscence defect, the surgeon must decide whether additional bone augmentation procedures should be conducted or, alternatively, whether a delayed approach would be a better choice. Studies have demonstrated that the potential for spontaneous bone formation at such defects is poor (4, 30). It has also been shown that predictable augmentation of dehisced sites associated with immediate implants is possible using resorbable non-resorbable membranes alone or in combination with autogenous bone grafts bone substitutes (8, 11). However, it is worth noticing that bone augmentation procedures on the other hand may also compromise the treatment outcome. Complications related to bone grafting and early membrane exposure has been described (31, 32). One of the challenges in relation to implant placement in fresh extraction sockets is achievement of sufficient primary wound closure, which otherwise may increase the risk of exposed membranes and possibly also lead to impaired aesthetics. In an attempt to avoid or minimize, the size of gaps and fenestrations at immediate implants after placement, new implant designs have been developed. Conical-shaped or tapered implants have shown promising results with failure rates consistent with those observed for standard implants in healed sites and fresh or recent extraction sockets (33). However, there are currently no evidence proving that the tapered implant design is superior to cylindrical standard-implants (34). Likewise, wide-diameter implants have been used in healed bone and in extraction sockets with success (35, 36). One concern of placing wide implants might be that presence of fragile bone walls or concavities in the alveolar bone may lead to dehiscences or fenestrations. There are only few reports on this topic and more studies are needed to verify the advantages and disadvantages of this type of implants. It can be concluded, that a gap around the implant placed immediately in an extraction site has good potential to heal. With the presence of a dehiscence the healing potential is poor and it is not known if one technique might be superior to others for augmenting bone in such a case. Should immediately placed implants be submerged in the healing period? The original implant treatment protocol recommended that the implant should be covered with mucosa after placement to ensure osseointegration. The rationale was partly to protect the implant site from bacterial contamination, partly to avoid loading of the implant. Today, the use of non-submerged (transmucosal) implants is a well-established treatment option, which has proven to perform equal to the submerged approach. When letting the implant penetrate to the oral cavity just after placement, two options exist: (i) mounting of a healing cap or (ii) mounting of a restoration. The latter option will be discussed in the following section. As gaps around the implant frequently are present after immediate placement and these in some cases need to be treated with bone grafting or membranes, it is relevant to question whether transmucosal implants placed in extraction sockets may be successful. Several investigations have demonstrated that non-submerged, immediately placed implants have good results (34, 37 41). High survival rates and predictable bone generation around transmucosal immediate implants treated with resorbable or non-resorbable membranes and or bone grafting were found. However, it should be emphasized that only short-term outcomes were presented. Is immediate or early restoration loading of immediately placed implants an option? Removal of a tooth will often have a negative psychological effect on the patient. Many people would prefer to leave the dental practice with a replacement for the extracted tooth, particularly if the anterior region is involved. As the use of an

TIMING OF IMPLANT PLACEMENT TO TOOTH EXTRACTION 37 interim removable prosthesis may be inconvenient to the patient and a provisional resin-bonded fixed prosthesis is difficult for the dentist because of lack of space when the abutment teeth are not to be prepared, it would be tempting to restore the implant immediately, or alternatively soon, after tooth extraction with a provisional restoration. The implant restoration could either be immediately early functionally or non-functionally loaded (42). Non-functional loading means that the restoration is out of occlusion. Recent reviews have reported on the combination of immediate implant placement and immediate restoration loading (12, 43 45), but their conclusions are in conflict. In one review (45), it was concluded that the success of immediate or early loading of implants may not be compromised by placement in extraction sockets as long as placement in sites with a history of marginal periodontitis is avoided, while Quirynen et al. (12) conclude that the incidence of implant loss is higher when combining immediate placement and immediate loading. Ganeles and Wismeijer (44) calculated an overall success rate of 96Æ4% for eight publications. All reviews agreed in that achievement of primary implant stability is a prerequisite for treatment success. Furthermore, it was emphasized that only short- mediumterm studies exist. It should also be stressed that evidence for success in the maxilla as well as the posterior mandible of immediate loaded implants placed in fresh extraction sockets or in healed bone is limited. In a recent study (46), 50 implants were placed in partially edentulous areas in maxillae and posterior mandibles directly into extraction alveoli, and temporary prostheses were connected immediately after surgery or within 7 days ( early function ). None of the implants failed in the 18-month follow-up period. Cannizzaro et al. (47) demonstrated high success of 202 implants (53 inserted in fresh extraction sockets) placed with a flapless technique in fully edentulous maxillae. All restorations (21 fixed prostheses and 12 overdentures) were functionally loaded the same day of the surgery and followed for 1 year after loading. Two patients each lost one implant. In another study (48) 22 teeth (19 in the maxilla, 13 premolars) were replaced by implants and restored with temporary single crowns immediately after extraction in 22 patients. No clinical failures were observed during a period of 12 months. When interpreting the results of implant loading protocols, it is important to distinguish between immediate functional loading and immediate restoration, as the outcome of these two approaches may turn out differently. Despite the limited information available it may be stated that a good prognosis has been observed following immediate early functional or non-functional loading of immediately placed implants. A risk of more implant failures exists where it is difficult to obtain primary implant stability. Does the type of restoration on immediately placed implants affect the outcome? In two recent systematic reviews, it was concluded that implant survival and success may not be affected by the type of implant prostheses employed. Bryant et al. (49) did not find clear evidence that neither fixed nor removable prosthodontics were superior to the other for rehabilitation of the completely edentulous jaw, or that splinted or non-splinted implants supporting overdentures performed better than the others. In a review on implant treatment of the partially edentulous patient, statistical significance was not reached for differences between the outcomes of single-implant restorations and implant-supported fixed partial prostheses (50). A study of Watzek et al. (51) demonstrated equal results for removable and fixed complete prostheses supported by immediately, early, or late placed implants in 20 patients. Likewise, several clinical trials have demonstrated that immediately placed implants can work excellent as support for complete and partial removable or fixed prostheses, including single-implant crowns. However, in studies dealing with different types of prosthetic restorations data are most often pooled and very few comparative studies exist. There seems not to be sufficient evidence to give a clear statement whether or not the type of restoration on immediately placed implants affects the outcome. Does location of the immediately placed implant affect the outcome? Favourable loading of implants is considered to be important to prevent complications. When placing an implant in a fresh alveolus, particularly if immediately exposed to the oral cavity (transmucosal) or immediately early restored, it might be expected that loading conditions play an even bigger role for treatment success. The magnitude of masticatory forces applied to teeth or implants varies depending on the location in the jaws with greater forces in the posterior regions. If only for that reason, one could imagine that immediate implant placement would be more challenging for replacement of premolars and molars.

38 L. SCHROPP & F. ISIDOR Additionally, extraction of a molar will normally leave a rather large socket, which may impede achievement of primary stability and increase the risk of bone defects around the implant just after placement. Implant success is also associated with bone quality. The density of the alveolar bone varies considerable in the different jaw segments with the highest density normally found in the anterior mandibular region and the lowest in the maxillary posterior region. This suggests that implants replacing molars or premolars in the maxilla may be at more risk. Finally, anatomical structures, such as the maxillary sinuses and the mandibular canal, in the vicinity of the implant recipient site may compromise the treatment. This is particularly true in relation to immediate placement because of the fact that the implant frequently must be placed several millimeters apically to the bottom of the alveolus in order to achieve primary stability. There is no evidence in the literature suggesting that placement of implants into fresh or recent extraction sockets should be restricted to certain locations. Several studies have shown predictable results of immediate placement of implants after tooth extraction at maxillary or mandibular molar sites (36, 52 57). Survival rates between 89% and 100% were found with followup periods from 6 months to 5 years. One study (52) revealed a better prognosis after 5 years for implants in the mandible (CSR of 92%) compared with the maxilla (CSR of 82%). Even though immediate replacement of molars with implants seems to be a safe method, adverse conditions at the implant site, e.g. insufficient amount of bone, poor bone quality, or conflict with adjacent anatomical structures, may rule out the possibility of following this protocol in specific cases. Therefore, careful case selection is still an important part of the treatment planning. Does immediate implant placement affect the aesthetic results? Improvement of the aesthetics has frequently been pointed out to be one advantage of immediate or early implant placement. The rationale is that soft and hard tissue may be preserved by using this protocol; however, as discussed elsewhere in this review, this issue is still of debate. Contradictory conclusions have been reached in a direct comparison of the aesthetic outcome following the early and delayed placement techniques (7, 58). Gotfredsen (58) using a submerged technique found that delayed placement (12 weeks) after tooth extraction performed better than early placement (4 weeks), whereas Schropp et al. (7) concluded that early placement (on average 10 days after extraction) of single-tooth implants may be preferable to delayed implant placement technique (12 weeks) in terms of early generation of interproximal papillae and the achievement of an appropriate clinical crown height. On the other hand, at 1Æ5 years after mounting the crown on the implant no difference in papilla dimensions was seen between the groups. Other factors than the timing of implant placement may be more important for the achievement of optimal aesthetic results: position and angulation of the implant, bone and or soft tissue grafting, gingival biotype, implant design, submerged versus non-submerged implants, immediate early restorations, and flapless procedures. Recently, several articles have been published on flapless implant surgery. This modified technique has been applied in cases of implants placed in extraction sockets as well. High survival rates and satisfactory aesthetic results were achieved for anterior maxillary single-tooth implants placed without incisions or flap elevation (59, 60), and Cannizzaro et al. (47) demonstrated successful outcomes after 1 year for immediately loaded implants placed with flapless surgery in fully edentulous maxillae. One drawback of placing implants without raising a flap may be that visual inspection of the recipient site is markedly reduced. Furthermore, the access to performing tissue augmenting procedures is very limited. When interpreting the results of studies dealing with flapless surgery, it is very important to pay attention to the inclusion and exclusion criteria. In some studies (60, 61) implant sites showing bone fenestrations, bone dehiscences, or larger peri-implant infrabony defects were excluded. Immediate placement of an implant may improve the shortterm aesthetic results, but a definitive conclusion cannot be drawn. Does immediate implant placement affect patient satisfaction? Success of dental treatment has traditionally been evaluated from the clinician s viewpoint. However, the significant treatment outcomes from the patient s perspective may differ from those of the dentist. High comfort, improved aesthetics, better chewing function, better phonetics are parameters typically considered being important to the patient, while probing pocket depths, degree of osseointegration, crestal bone levels, etc. are of minor significance. Recently, more focus has

TIMING OF IMPLANT PLACEMENT TO TOOTH EXTRACTION 39 Table 1. Summary of conclusions and authors suggested guidelines for immediate or early implant placement Literature Overall outcomes Survival rates (SR) Crestal bone loss (CBL) Probing pocket depth (PPD) Preservation of alveolar bone Infection at the extraction site Peri-implant defects Submerged vs. transmucosal implants Immediate placement and immediate restoration loading Type of restoration Location of implant site Conclusions A vast number of studies were found. However, only a few randomized controlled trials (RCT) or long-term prospective trials exist SR for immediately, early, delayed, or late placed implants are equal, amounting to approximately 95% in the short perspective No statistically significant differences in mean crestal bone loss between the protocols No statistically significant differences in mean probing pocket depth between the protocols Capability of immediate implants to preserve the alveolar bone is controversial Morphologic changes of the post-extraction site may occur despite immediate early implant placement Damage to the alveolar bone may occur during tooth extraction Controversies exist on whether local pathology has an adverse effect on the outcome There is no evidence to recommend the use of antibiotics prophylactically, apart from in medically compromised patients A history of marginal periodontitis may endanger treatment outcome. The explanation might be that achievement of primary stability is impeded, and or that remaining infection is harmful to osseointegration Small gaps between implant surface and socket wall have a potential for spontaneous healing GBR and grafting perform successfully for augmentation of dehiscences and fenestrations; however, no evidence exists that one technique or material is superior to others Complications related to bone grafting and early membrane exposure has been described Tapered implants are not superior to cylindrical, standard implants No significant differences between the two protocols Better aesthetics after non-submerged implant placement has not been convincingly demonstrated High success of this treatment modality implemented in the anterior mandible has been found. Limited data are available for the maxilla and posterior mandible Immediately placed implants can work excellent as support for complete and partial removable or fixed prostheses, including single-implant crowns Removable and fixed complete prostheses perform equally well in terms of implant success Scarce information in the literature Successful immediate implant placement may be possible in all regions of the jaws Clinical guidelines Slightly palatally lingually placement of the implant in the extraction socket to avoid exposure of the implant surface Careful extraction is recommendable. Multi-rooted teeth should be sectioned before removal Chronic infection is not an absolute contraindication for immediately placed implants, however, thorough debridement of the alveolus should be made The use of antibiotics should mainly be used in medically compromised patients One should be more cautious when replacing teeth lost because of marginal periodontitis with immediate implants Bone augmentation procedures should be restricted to dehiscences, fenestrations and larger infrabony defects Possibility of wound closure should be considered when choosing submerged technique Immediate loading of immediately placed implants may be a viable treatment option in the anterior region of the mandible Achievement of primary implant stability is a prerequisite for success No recommendations for the design of implant-supported prostheses can be made because of insufficient evidence Replacement of molars is more challenging and careful case selection should be made

40 L. SCHROPP & F. ISIDOR Table 1. (Continued) Aesthetics Flapless vs. flap elevation Patient satisfaction Conclusions Data on the aesthetic outcomes following immediate early implant placement are inconclusive Implant placement with the flapless mode can offer successful outcomes. Improved aesthetics of this technique has not been proven Immediate early implant placement may offer high patient satisfaction concerning aesthetics and functional outcomes Clinical guidelines Other factors than timing of implant placement should be considered to obtain favourable aesthetic results The flapless technique requires careful case selection, as visual inspection and performance of bone augmentation procedures are hampered been put on patient-based outcome measures in the assessment of dental treatment in general (62, 63). It has been demonstrated that high patient satisfaction with the aesthetic outcome of implant-supported single-tooth restorations can be achieved (5, 64 68). Reduction of treatment time and fewer surgical interventions are advantages of immediate early implant placement. Therefore, this protocol might be expected to increase patient satisfaction. A study (69) combining immediate placement and immediate loading of 33 single-implants showed satisfactory aesthetic and functional results from the patients viewpoint. In a RCT (5) comparing early and delayed implant placement overall satisfaction of the treatment was highest with the early placed implants, while no significant differences between the groups in patient assessment of shape, colour, chewing function, and ease of cleaning were found. It can be concluded that patients treated with the immediate implant placement protocol are highly satisfied. Classification Various terms and classifications have been suggested for the timing between tooth extraction and implant placement, which may make it difficult to compare the outcome of previous studies of the literature. As an alternative to using a strict indication of time between the procedures, Hämmerle et al. (70) proposed a new classification based on soft and hard tissue healing parameters: (i) Implant placement immediately following tooth extraction and as part of the same surgical procedure. (ii) Complete soft tissue coverage (typically 4 8 weeks). (iii) Substantial clinical and or radiographic bone fill of the socket (typically 12 16 weeks). (iv) Healed site (typically >16 weeks). This classification seems appropriate, as it considers variations in subjects healing capacity. Irrespective of using one or another classification, there is obviously a need for uniformity in this regard. Conclusions Based on a review of the current literature, it can be concluded that immediate or early placement of implants may be a viable alternative to delayed placement. However, it is at the same time very important to emphasize that several clinical parameters have to be considered if this treatment option shall succeed. Along with careful case selection, the surgical and prosthetic protocols must be closely followed. In the authors opinion the immediate implant placement procedure is technique-sensitive and may be more difficult to execute than the conventional procedure. Therefore, we advocate that this treatment modality should be restricted to well-trained dental teams. A summary of the conclusions and suggested guidelines are presented in Table 1. Conflicts of interest Both authors declare no conflicts of interest. References 1. Brånemark P-I. Introduction to osseointegration. In: Brånemark P-I, Zarb G, Albrektsson T, eds. Tissue-integrated prostheses. Osseointegration in clinical dentistry. Chicago, Berlin: Quintessence Publishing Co., 1985:11 76. 2. Esposito MA, Koukoulopoulou A, Coulthard P, Worthington HV. Interventions for replacing missing teeth: dental implants in fresh extraction sockets (immediate, immediate-delayed and delayed implants). Cochrane Database Syst Rev. 2006:CD005968. 3. Lindeboom JA, Tjiook Y, Kroon FH. Immediate placement of implants in periapical infected sites: a prospective randomized study in 50 patients. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2006;101:705 710.

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TIMING OF IMPLANT PLACEMENT TO TOOTH EXTRACTION 43 66. Chang M, Wennström JL, Ödman P, Andersson B. Implant supported single-tooth replacements compared to contralateral natural teeth. Crown and soft tissue dimensions. Clin Oral Implants Res. 1999;10:185 194. 67. Gibbard LL, Zarb G. A 5-year prospective study of implantsupported single-tooth replacements. J Can Dent Assoc. 2002;68:110 116. 68. Vermylen K, Collaert B, Lindén U, Björn AL, De Bruyn H. Patient satisfaction and quality of single-tooth restorations. Clin Oral Implants Res. 2003;14:119 124. 69. Ferrara A, Galli C, Mauro G, Macaluso GM. Immediate provisional restoration of postextraction implants for maxillary single-tooth replacement. Int J Periodontics Restorative Dent. 2006;26:371 377. 70. Hämmerle CH, Chen ST, Wilson TG, Jr. Consensus statements and recommended clinical procedures regarding the placement of implants in extraction sockets. Int J Oral Maxillofac Implants. 2004;19(Suppl.):26 28. Correspondence: Dr Lars Schropp, Associate Professor, Department of Prosthetic Dentistry, University of Aarhus, Vennelyst Boulevard 9, 8000 Aarhus C, Denmark. E-mail: lschropp@odont.au.dk