The aim of this literature review is to evaluate the outcomes of implants placed after extraction of teeth with infections of endodontic origin. An electronic search was performed through electronic databases (Medline and Embase) using the terms “immediate implant,” “post-extractive implants,” “endodontic infection,” “infected site,” and “extraction socket” combined with the use of Boolean operators (“AND” and “OR”). Only articles on human subjects were considered. At least 12 month of mean follow-up was required for inclusion. No restriction was placed regarding study design. Ten studies were included in this review. Survival rates ranged from 92% to 100%. A total of 497 implants were placed in sites with endodontic infection. In nine studies the use of bone substitutes was associated with immediate implant placement. Because of the low number of included studies and the heterogeneity of study design, more well-designed studies are required to assess the relevance of this treatment alternative.
Orthograde primary endodontic therapy is an effective treatment, as indicated by systematic reviews reporting success rates ranging between 31% and 100%1,2 ; the variability was mainly due to the inclusion criteria of the studies and to the adopted criteria of success. In cases of failures with persistent periradicular lesions, secondary endodontic treatment was recommended, and those outcomes were investigated in systematic reviews.3,4 Reported success rates for nonsurgical or surgical secondary treatment are greater than 70% for both,3,5 and no significant difference in outcomes between procedures was found.4,5 Endodontic surgery performed with a modern technique, that is, with the aid of microinstruments, magnification devices, and retrograde canal preparation through the use of ultrasonic retrotips, has been reported to achieve a success rate greater than 90% after 1 year.6
When the tooth pathologic condition cannot be solved with endodontic retreatment (either orthograde or retrograde) or in the presence of root fractures that become evident during diagnostic or treatment phases, the extraction of the involved tooth becomes the most indicated solution. Tooth extraction and immediate placement of dental implant in the extraction socket is a viable and effective technique in anterior zones7,8 and posterior regions, though many requisites need to be considered.
The presence of active infection in the extraction site is considered one of the main contraindications to immediate implant insertion in the socket because of the increased possibility of infection spreading to peri-implant tissues during the healing period.9–11 Animal studies showed that the presence of periodontal or endodontic infections, even in the active phase, did not compromise the osseointegration of immediately placed implants and did not reduce the bone-to-implant contact after the healing phase.12–16
The aim of this study was to review the existing literature about the immediate placement of implants in endodontically infected sites in humans and to discuss the clinical and scientific implications of this treatment modality.
Material and Methods
An electronic search was conducted in Medline and Embase for the period from January 1966 to August 2011 using a combination of different searches using the terms “dental implants,” “immediate implant,” “extraction socket,” “infected teeth,” “infected site,” and “infected socket.” The initial search yielded 264 titles and abstracts, which were independently screened by two reviewers (S.C. and S.T.). No restriction was placed regarding the language and the study design. For clinical studies, a minimum mean follow-up of 12 months was considered for inclusion. Only studies with a clear description of causes of teeth infections were included to allow the analysis. Animal studies were excluded from this review.
By screening titles and abstracts, a total of 10 articles were found that met the inclusion criteria.17–26 The 2011 study by Truninger24 presented updated data from the same cohort of patients treated in the 2007 study by Siegenthaler21 ; therefore, only the most recent study was considered.
Data extracted were (1) implant survival, defined as the implant in function without pathologic processes ongoing at the time of the investigation; and (2) reasons for tooth extraction, which were classified as endodontic cause, periodontal cause, root fractures, or combined endodontic-periodontal cause.
Data from clinical trials are summarized in Table 1. Considering all the included studies, a total of 523 implants were inserted in infected sites in 410 patients. The follow-up varied from 3 to 117 months from loading. Guided bone regeneration was performed in all studies with the exception of one23 to compensate for gaps between the fixtures and socket walls. The survival rate of the treatment was high in all evaluated studies, ranging from 92% to 100%.
Table 2 reports the nature of lesions affecting treated teeth, which were purely endodontic in 82.3% of cases. Periodontal lesions were diagnosed in 12.8% of sites, while root fractures and endo-perio lesions were less represented (1.4% and 1.0%, respectively).
Because of the different nature of periodontal and endodontic lesions, a separate analysis of implants placed only in sites with endodontic or endo-perio infection was performed (Table 3). A total of 497 implants were placed in sites with endodontic infection. The surgical protocol always included an accurate debridement of the sockets after teeth extractions.
The case series presented by Novaes Jr and Novaes17 was the first scientific article describing the immediate insertion of implant in infected sites. Three cases were presented with endo–perio lesions and root fractures associated with endodontic infections. In one of the described cases suppuration was observed. The teeth were extracted following a strict atraumatic protocol. An accurate debridement of sockets was then performed. Guided bone regeneration was also used to compensate for bone resorption due to chronic infection of the site. Follow-up time for the 3 cases varied from 7 to 24 months and was uneventful.
Years later other researchers18 compared the insertion of immediate implants in sites with chronic infections with a delayed implant insertion. After randomization, 50 implants were placed in maxilla: 25 were immediately placed after tooth extraction in sites affected with chronic periapical pathosis, and 25 were placed after a healing period of 3 months (control group). Guided bone regeneration was always performed in the first group. One year after the surgery the survival rate in the experimental group was 92%, which was not significantly different from that of the control group.
Casap and coworkers19 described and analyzed the immediate placement of dental implants into infected sockets (with chronic or subacute infections and initially affected by subacute periodontal infection, chronic periodontal infection, and endodontic periapical lesions) after accurate debridement. Of the initial 30 implants placed in 20 patients, only one was lost in the follow-up period, which varied from 12 to 72 months after surgery. Another implant was removed because it showed mobility after prosthetic restoration. Surgical complications, such as membrane exposure, were also reported, but they were always correlated to guided tissue regeneration procedures. Of the 10 implants placed in endodontically infected sites, only one implant was lost during the observation period.
In 2007, Villa and Rangert20 published their clinical investigation about the immediate and early function of implants placed in extraction sockets of infected maxillary teeth. A total of 76 implants were inserted in 33 patients with teeth considered hopeless because of endodontic lesions, periodontal lesions, or root fractures. Immediate loading of inserted implants was performed within 36 hours of surgery. After 1 year of function, 2 implants were lost, resulting in a 97.4% survival rate. No sign of infection was observed in peri-implant tissues. No failure occurred among the 21 implants placed in sites with periapical lesions. The authors concluded that the presence of infection in the site of the insertion is not associated to an increase of the risk of implant failure.
Del Fabbro and coworkers22 published the results of their prospective study investigating success and survival rates of implants placed in fresh extraction sockets with chronic endodontic infection. Sixty-one implants were placed immediately after teeth extractions and accurate debridement. Only one implant failed because of infection 2 months after insertion. All patients reported full satisfaction with the treatment. Bone resorption, measured through radiographic examination, was 0.41 ± 0.22 mm.
Crespi et al23 inserted 15 immediate implants in sites with chronic endodontic infection and 15 in patients with teeth extracted because of caries or root fractures. After 3 months, implants were loaded and follow-up visits were scheduled up to 24 months. Cumulative survival rate was 100% in both groups. Soft and hard tissue healing around implants was equal between the 2 groups.
In 2011, Truninger et al24 published the 3-year results of the comparative study in which the 1-year results were previously published in 2007.21 Thirteen implants placed in infected sites (8 of which presented suppuration before tooth extraction) were successful after 3 years from placement.
In 2011, Bell and coworkers25 reported data from a retrospective investigation of 285 implants placed in sites with chronic endodontic infections. The follow-up varied from 3 to 93 months. The cumulative survival rate for implants in infected sites was 97.5%, which was not significantly different from the survival rate of implants placed in sites without infection.
Another retrospective comparative investigation26 reported long-term data for implants placed in sites with periapical infection. A 100% survival rate was observed for 64 implants with a follow-up varying from 24 to 117 months, which was not significantly different with respect to the outcome of implants placed in healed sites.
Eight of the included studies described the application of guided bone regeneration techniques with the use of resorbable and nonresorbable membranes in conjunction with autologous or etherologous bone filler as described in Table 4.17–20,22,24–26 In 2 studies, platelet concentrates were used in the surgical procedure.22,25 No differences were reported in terms of implant survival rates.
Antibiotic prophylaxis was administered in 7 studies with different modalities (Table 4).17–20,22–24 In one study, antibiotic therapy was generally cited without any specification,25 and in another study it was not reported.26 Antibiotic therapy was prescribed in 7 studies after surgical treatment.17–20,22–24
The success of primary endodontic treatment was influenced and determined by many factors that may influence the outcome of this procedure.2 Presence or absence of periapical lesion (identified through radiographs) in the apical portion of teeth, an adequate coronal restoration, and a correct and complete filling of the root canal extending within 2 mm from the radiologic apex could significantly influence the outcome of primary endodontic treatment.2 Similar criteria were also considered as positive prognostic factors for nonsurgical retreatment, although the scientific literature is scarce.3,5 Tsesis and colleagues6 reported high success rates for endodontic surgery performed using a modern microsurgical protocol. However, most of the prospective controlled studies included in evidence-based systematic reviews estimate the treatment effect in an ideal situation as they are normally carried out using a standardized protocol with selective inclusion criteria, experienced surgical teams, and controlled variables. Therefore, such studies do not closely reflect the everyday clinical practice in which there is a much larger variability in study parameters.
Some epidemiologic studies reported the success rate of endodontic orthograde treatment by presenting retrospective data from large sample populations. In 2007, Chen and colleagues27 reported that 5 years after endodontic treatment, 89.7% of teeth were healthy and there were no complications, demonstrating a high success rate of the treatment even when the techniques are performed by different dentists. In this study, the tooth retention rate was 92.9%, which was comparable with rates reported in previous studies.28,29 These results were confirmed by another more recent study.30
Hence, endodontic primary and secondary treatment could also be considered viable treatment options in cases with persistent apical periodontitis. In treatment planning, however, the heterogeneity of the reported results should be taken into consideration together with patients' expectations.
Recent reviews evaluated nonsurgical endodontic treatment versus single-tooth implants.31,32 They concluded that implants and nonsurgical endodontic treatment followed by prosthetic restoration are both excellent treatment modalities, and the choice of the treatment plan should not be based on outcomes evaluation only.31
Other factors, such as the impossibility of achieving an optimal coronal seal with the postendodontical restoration, root fractures that may be evident during periapical surgery, or failures of endodontic surgery, may lead to tooth extraction and replacement with implants. Also patients' preference has to be considered to fully satisfy their expectations and obtain better compliance.
Immediate implant placement in fresh extraction sites is a viable technique with success rates comparable to those of implants inserted in healed sites.10 Presence of active infection was considered one of the major contraindications of immediate postextraction insertion of implants.9–11
The scientific literature on immediate implants in infected sites is poor. Only 10 studies were found and included. Clinical studies reviewed in the present study reported high survival rates, comparable with those reported in studies describing immediate implant insertion in noninfected postextraction sites.33
In all studies, tooth extraction was always described as atraumatic, and an accurate debridement of the residual socket was reported to be necessary to thoroughly remove the lesion, reducing the risk of early infection of the tissues surrounding the implant. Furthermore, none of the authors of the included studies reported that presence of suppuration was correlated with an increased failure rate. So, an accurate and complete lesion debridement, associated with antibiotic prophylaxis and therapy, appears to be sufficient to avoid perisurgical infective complications and massive bone loss.
Eight studies reported the use of guided bone regeneration to fill gaps between implant and socket and to treat bone dehiscences due to the previous inflammatory process, if present. No differences were highlighted in implant survival rates using different materials and techniques for guided bone regeneration, even if it was observed that exposure of nonresorbable membrane could have a negative effect on implant osseointegration. This may be considered a relative contraindication in this treatment protocol.
Notwithstanding the limitations of this review related to the small number of studies, the heterogeneity of protocols, the size of samples, and the follow-up period, the present analysis could be useful for quantifying the evidence on major therapeutic alternatives for endodontists. In general, the decision-making process should not only rely on the success rates of the treatment and on the available evidence but must also take into account the patients' expectations and preference as well as the surgeon's skills and attitudes. A clear difference in success rates among surgical retreatment, nonsurgical retreatment, and immediate implant insertion in endodontically infected sites is still not demonstrated. Hence, tooth preservation should be considered the primary treatment option in cases of infected hopeless teeth; thus, immediate implant placement represents an increasingly accepted treatment option.
Immediate implant insertion in infected sites could be considered a viable alternative to secondary endodontic treatment. More well-designed, randomized, controlled trials with a longer follow-up are required to confirm implant insertion in infected extraction sockets as a safe procedure with long-term, high success rates.