The present report showed that short implants may achieve optimal clinical and radiographic outcomes at the 1-year follow-up when used for single restoration or when connected with other implants in substituting for more than one tooth. There was no difference in outcomes between mandibular and maxillary restorations even though a higher quantity of bone volume was required in mandibular restorations because of the need for a safe distance from the IAN as described in previous reports.

Several systematic reviews of the literature have evaluated the outcomes of short implants used for the rehabilitation of edentulous jaws. In 2010, Neldam and Pinholt included 27 studies describing implants <9 mm long. They reported failure rates ranging from 0 to 37.5%, with no significant difference among different implant lengths. They also found that most bone loss occurred during the first year of loading.

In 2011, Pommer and coworkers  evaluated the effect of implant length on early failure rates. The meta-analysis reviewed 54 observational studies and 19,083 implants. They observed that shorter implants (<10 mm long) demonstrated a higher failure rate than longer implants even though the computed odds ratio was only 1.8. Moreover, considering only rough-surfaced implants, the failure rate was between 0.4% and 1.8% for short implants and between 0% and 1% for longer implants, showing a relevant effect of implant surface on overall survival rate.

In another recent systematic review of short implants, Annibali and coworkers reported a cumulative success rate of 99.1% after a mean period of 3.2 ± 1.7 years from 16 studies (6193 short implants). A higher failure rate was reported for the anterior maxilla (mean survival rate = 88.4% in 3 studies); more than half of the considered implants were placed in the posterior mandible (n = 3400). The analysis of bone loss found that only one study reported amount of bone resorption over time, showing that the great majority of implants had no bone loss.

In the present report, the success and survival rates were coherent with those presented in the previously cited systematic reviews, demonstrating that if an accurate surgical protocol is applied, short implants can be a viable treatment alternative in cases of reduced bone height.

Some authors have stated that wetting the implant surface with liquid P-PRP enhances osseointegration and tissue stability over time because the platelet concentrate can stimulate the osteoblasts, creating a bioactive interface. Moreover, P-PRP can allow better soft tissue healing after implant placement and after second-stage surgery. In fact, P-PRP releases factors that are involved in promoting tissue regeneration, such as fibrinogen, fibronectin, platelet-derived growth factor, transforming growth factor-β, vascular endothelial growth factors, and others. The concentrate has a marked anti-inflammatory action that suppresses such pro-inflammatory chemokines as interleukin-1 and has an antimicrobial effect. These characteristics, together with the hemostatic properties and high biocompatibility, contributed to the favorable action on soft tissue healing.

The use of short implants should be considered as an alternative to bone grafting procedures in sites where there is insufficient bone for the placement of longer implants. A recent randomized controlled trial (RCT) compared the 3-year outcome of short implants versus sinus augmentation for the rehabilitation of atrophic posterior maxilla. Thirty-four patients per group were treated with a total of 144 implants (73 in the sinus augmentation group and 71 in the short implants group). Two early implant failures were reported after sinus augmentation but only one late failure was described for short implants. Interestingly, only one membrane perforation occurred during the placement of a short implant but 8 perforations were reported during sinus lifting procedures. Even though the reported bone loss for short implants was slightly higher than the loss reported in the present study (0.52 ± 0.43 mm at 1 year and 0.71 ± 0.38 mm after 3 years) this difference appears to be negligible, and data can be considered similar.

Another RCT compared 7-mm-long implants to vertical augmentation in the rehabilitation of posterior mandibles reporting 1-year results. Thirty patients per group were treated with 61 implants in the augmented group and 60 implants in the short implants group. No statistically significant differences in outcomes were reported even though a higher number of implants failed in the augmented group. No nerve injuries were reported, though 4 wound dehiscences were observed in the augmented group. The mean alveolar bone loss was rather high in both groups 1 year after prosthesis placement (1.79 ± 0.54 mm for short implants and 1.65 ± 0.42 mm for longer ones in augmented bone).

In summary, such comparative articles showed that short implants can be a good alternative to more demanding augmentation procedures in cases of bone atrophy in the posterior jaw. However, it has to be considered that a lateral approach sinus floor elevation can be successfully performed even in the presence of <4 mm of residual bone height, while short implants can be placed only in cases where there is enough bone volume to obtain primary stability after implant placement.

Several limitations of the present study should be highlighted. First, the nature of the study was not comparative; hence, the results should be considered carefully when evaluating short implants as a treatment alternative. Furthermore, the follow-up duration could be considered short, though in the literature most failures occurred early during the first 6–9 months after prosthetic loading. The relatively short follow-up may have influenced the evidence that there were no differences in bone resorption between splinted implants and single implants and among different opposite occlusing surfaces, whose effects can be hypothesized to be observable in longer periods of observations. Moreover, the small sample size and the variability of implant sites may limit the external validity of the reported results. Finally, most of the implants were 4 mm in diameter and this could have confounded the results, even though it provided a bone-to-implant contact comparable with that of longer but narrower implants.

Despite the limitations of this study, short implants should be considered as a viable treatment alternative for the rehabilitation of edentulous jaws in cases of reduced bone volume. The absence of surgical and postsurgical complications has to be considered in choosing a treatment and should be taken into account in light of the possibility of adverse sequelae related to augmentation procedures. More well-designed RCTs comparing the use of short implants versus augmentation procedures with longer follow-up will help to better understand the clinical performance of the treatment options described in this report.