Review - ZZI 02/2010

In which bisphosphonate patients am I allowed to place implants? A systematic review

K. A. Grötz1, B. L. J. Schmidt, C. Walter, B. Al-Nawas

Bisphosphonates (BP) result in a positive tissue balance in bone, largely due to the antiresorptive effects at the osteoclast level, but are associated with osteonecrosis of the jaws (ONJ), which is hard to treat. There have been several attempts to improve medical care for patients receiving bis-phosphonates through enhanced communication between physicians prescribing bisphosphonates and dentists. The aim is to minimize the risk of developing BP-ONJ. In this contentious field, implantation is of special importance; in the last 20 years, many (alleged) contraindications for implants have been put into perspective, but BP-ONJ may be a new one. The literature-based evidence reflects the limited current knowledge of the real risk of implant-related ONJ or implant loss due to BP-ONJ. Against the background of existing experiences, an algorithm for indications can be developed. Three criteria are of high clinical importance: (1) the individual’s BP-ONJ risk (which can be evaluated with the ASO control slip), (2) the increase or decrease in risk due to an implantation and (3) the necessity of augmentative procedures. This allows a methodical, understandable decision for each patient, regarding the suitability of implant-borne prosthetic rehabilitation.

Keywords: bisphosphonates; implants; prognosis; compromised bone bed; osteoporosis; bone metastases; augmentationIntroduction

Awareness of the fact that patients treated with bisphospho-nates (BP) can develop bisphosphonate-associated osteonecrosis of the jaw (BP-ONJ) has become widespread among prescribers of BP and among dentists, oral surgeons and maxillofacial surgeons since it was first described in 2003 [21]. The basic principles of prevention before, during and after BP therapy and of early identification of BP-ONJ are reflected in the DGZMK [German Society of Dentistry and Oral Medicine] statement [14]. With regard to the treatment of overt BP-ONJ, the wide range of recommendations available initially, ranging from purely conservative to radical surgical measures, have narrowed and led to the first consensus [1].

Currently, there is still great therapeutic uncertainty regarding implant placement, since the potential BP-ONJ risk is of particular relevance with an elective procedure.

In the following, an attempt is therefore made to develop a decision-making algorithm for the implant indication on the basis of the available clinical experience and the recent literature.

Clinical problem

Every operative procedure (thereby including implant placement) is associated with the theoretical risk of endosteal microbial contamination, and can therefore be regarded as a cause of BP-ONJ. On the other hand, pressure sites due to (purely or predominantly) tegument-borne dentures are a quite typical local cause of BP-ONJ (Fig. 1), raising the question clinically of whether the ONJ risk is not actually reduced in these cases by implant placement with the reduction of the degrees of freedom of the prosthesis. In addition, the conclusion that the risk of BP-ONJ can be construed as a fundamental contraindication to implants is not always confirmed by clinical experience.

Available evidence

A standardized literature search was conducted using the Medline, PubMed, Cochrane and Embase databases. The search strategy comprised selected key words such as “dental implants”, “bisphosphonate”, “osteonecrosis”, “jaw”, “quality of life”, “osteochemonecrosis” and “risk factors”. To capture the relevant content, MeSH terms were added to the literature search. In addition, the German literature of the last ten years was searched manually (Deutsche Zahnärztliche Zeitschrift [German Dental Journal] and Zeitschrift für Zahnärztliche Implantologie [Journal of Dental Implantology]). Regardless of the language, all primary studies (excluding meta-analyses) that dealt with the topic of bisphosphonates and endosteal implants were included.

The evaluation was grouped as follows:

1. BP as a negative prognostic factor for implants?

The evidence of jaw necrosis caused by implants is available only as case reports [LoE IV] [7, 28, 35].

Based on the literature at evidence level IV [LoE IV], two case reports [29, 36] point to a possible negative influence of BP on implant prognosis, with the case study published in 2007 reporting oral BP therapy lasting longer than ten years. From 2009, there is a retrospective analysis in the design of a case control study [18] [LoE III], which reports a poorer implant survival rate in eleven BP patients with 35 implants compared with 40 control patients with 161 implants (Tab. 1).

2. BP not a negative prognostic factor for implants?

In several case studies, an uncomplicated course is reported with oral BP medication and different non-malignant underlying diseases [4, 24, 32, 33] [LoE IV]. Furthermore, there are several retrospective analyses on the topic of bisphosphonates and implants which include a larger number of cases [2, 8, 11, 17, 27] [LoE III].

The chronologically oldest of these retrospective analyses reports on 61 female patients who had taken alendronate or risendronate (35/70 mg) as osteoporosis therapy for between one and five years [8] – 22 of them were provided with 39 immediate implants. After a twelve to 24-month follow-up period, the authors report no significant complications. However, it should be noted that the antibiotic prophylaxis, consisting of amoxicillin for ten days, is extremely prolonged for German circumstances. The implant survival rate was 100 % (Tab. 1).

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