Immediate loading in partially and completely edentulous jaws: a review of the literature with clinical guidelines

The introduction of immediate loading was a paradigm shift in implant dentistry as it was previously believed that an unloaded period was essential for bone healing in order to promote osseointegration. However, this belief could not be confirmed by clinical studies or by human histology. Hitherto, numerous reports have been published on immediate loading in various indications. An important factor for success is primary implant stability. The latter can be improved by adapting drilling protocols to enhance lateral compression of the bone and by using tapered implant designs with apical thread fixation. To some extent, the use of implants with a microrough surface and rigid splinting may compensate for suboptimal stability. It is important to avoid fracture of the provisional restoration at all times as this may result in local overloading and implant failure. Also, unevenly distributed occlusal contacts may contribute to failure and therefore occlusion ought to be evaluated at every occasion, especially during the early phase of healing. Taking these aspects into account, immediate loading in the fully edentulous mandible by means of an overdenture has been shown to be predictable in terms of implant survival (94.4-100%). However, the procedure may result in additional costs as a result of the need for repeated relining. In addition, the scientific basis for this treatment concept in the maxilla is very scarce. Immediate loading in the fully edentulous jaw by means of a fixed prosthesis is a well-documented treatment concept. In the mandible, three implants have been shown to be insufficient, given the failure rate of up to 10%. With at least four implants a failure rate of 0-3.3% may be expected. In the maxilla, four to six implants could be too limited, given the failure rate up to 7.2%. Increasing the number of implants may reduce implant failure to 3.3%. Provisional fixed prostheses are particularly prone to fracture in the maxilla and hence reinforcement is warranted. Immediately loaded single implants have lower survival rates, of 85.7-100%, with no clear impact of occlusal contact. In fact, a meta-analysis demonstrated a five times higher risk of failure for immediately loaded single implants when compared with delayed loading. No study showed superior soft-tissue preservation or esthetics following immediate loading of single implants compared with other loading protocols. However, this finding may not imply that a provisional implant crown becomes redundant when soft-tissue conditioning is deemed necessary. Taking into account earlier factors for success, immediate loading in the partially edentulous jaw by means of a fixed prosthesis seems predictable in terms of implant survival (95.5-100%). However, there are no studies with data on soft-tissue parameters, esthetic aspects or patient-centered outcomes, and the available studies mainly relate to the load-carrying part of the dentition. Clinical studies focusing on these aspects of treatment outcome are clearly needed. High patient satisfaction is the most important advantage of immediate loading, especially during the early healing phase. In this context, one should also realize that studies have revealed comparable patient satisfaction in patients following delayed loading once their prosthesis is in place. In the decision-making process, this aspect should be properly discussed with the patient along with other advantages and disadvantages of immediate loading.