Implant rehabilitation in the posterior regions of the maxilla and mandible can be complicated in cases of reduced bone volume due to bone resorption after teeth extraction or to particular anatomic conditions. In fact, reduced bone height can prevent long implants (>10 mm long) from being placed because of the risk of involving anatomic structures, such as the maxillary sinuses or inferior alveolar nerve (IAN), during implant placement.

Sinus lifting techniques consisting of a lateral and transcrestal approach for augmenting available bone before implant placement in the posterior maxilla are widely validated in the scientific literature.  Even though a high survival rate has been reported for both techniques the risk of surgical complication is relatively high, especially regarding sinus membrane perforation, which occurs in 20%–44% of cases with a lateral approach. Complications are also frequently reported with the transalveolar technique, though the rate of membrane perforation rate might be underestimated because the latter is a blind technique. In fact, it was reported that membrane injuries during transalveolar technique cannot be clinically detectable.  Other complications include postoperative infection and total graft failure, which occur in <3% of cases as described in the literature. Knowledge of maxillary sinus anatomic features and a careful preoperative evaluation are important for preventing such complications.

While evaluating treatment alternatives for rehabilitation of the posterior mandible the distance between the bone crest and the IAN is a key factor that can limit treatment options. In cases of inadequate bone volume many surgical procedures can be adopted to augment the volume in the posterior inferior jaw. Vertical bone augmentation through guided bone regeneration has been proposed, even though only a few studies have reported the results of this approach.  Reduced bone height can also make the surgical procedure difficult to perform. Moreover, use of autogenous bone block graft should be evaluated, taking into account the adverse sequelae that can follow the harvesting procedure. The incidence of complications is relatively high, and accurate preoperative planning and examination are required to reduce the incidence. Other techniques, such as IAN transposition, should be considered carefully because of the relatively high risk of injury during the surgical procedure. Furthermore, the longer rehabilitation times usually necessary after augmentation procedures should be considered when evaluating treatment alternatives.

The use of short implants has been suggested as an alternative to bone augmentation for the rehabilitation of edentulous jaws, particularly in the posterior areas. Short implants have been defined as those shorter than 11 mm, shorter than 10 mm, or shorter than 8 mm. In the latter case the authors considered only the portion of the implant inserted into the bone, which must be ≤8 mm, instead of the actual length of the implant. Though some reports have correlated the use of short implants with unpredictable outcomes, more recent reviews showed better clinical results for these kind of rehabilitations. Also, in the long-term, even though several prosthetic complications have been reported, a high survival rate was described for short implants placed in posterior areas of the jaws.

The aim of this prospective study was to assess the clinical and prosthetic performance of short implants supporting mandibular and maxillary rehabilitations and to evaluate marginal bone resorption after 1 year of loading.