# Complete Full Arch Supported by Short Implant (<8 mm) in Edetulous Jaw: A Systematic Review
## 4 Discussion
As mentioned earlier, the reasons for the good results with short implants may be related toa high initial primary stability and the effective use of residual bone volume with high primary bone-to-implant contact in dense bone structures. [PERSON] et al. [28] also showed in a recent review how the failure rate with short implants is related to surgical operator learning curves, osteotomy preparation (regardless of bone density), the use of surface-machined implants, and placement in sites with low bone density [35]. The prevalence of biological complications was not relevant to the type of prosthetic restoration. The most common biological event observed was residual plaque accumulation and increased (>4 mm) pocket probing depth at various follow-ups. The relationship between plaque accumulation and gingivitis or periodontitis is well documented in the literature as an important late risk factor for implant failure. [PERSON] et al. [27] had already shown that plaque accumulations around implants induce local inflammation and progressive marginal bone loss over years. In the studies considered for this review, none of them evaluated and found risk factors that could lead to peri-implant pathology or signs of peri-implantitis [17; 36]. [PERSON] et al. [2] in another study showed that a total of 160 implants were placed in thirty-seven patients, while in three patients, both arches were rehabilitated. Forty full arch rehabilitations were performed, of which only fourteen were in the mandible, and only five implants failed with an overall implant survival rate of 96.9%. BoP was detected in about six implants (3.7%) and sixteen implants had a superficial amount of plaque, with a plaque score of 10%. [PERSON] et al. [37], in a review, showed that for fully edentulous mandibles, short implants are a reliable therapeutic alternative, as survival and MBL were not different from those of inserted long implants. In contrast, it was shown in this study that the prevalence of prosthetic complications was very different for both types of prostheses loaded on short implants (fixed or removable). In a review, [PERSON] et al. [17; 24; 25; 30; 33; 36; 38] showed that failures with fixed full-arch restorations were more frequent and common and reported that the prosthetic failure rate reached 62.5 percent, considering that seven prostheses were installed and three debondings of five restorations and three fractures of the prosthetic structure occurred. This could be due to the presence of the distal cantilevers. Very interesting is the review by [PERSON] et al. [39], who, in a study, demonstrated that when 13 arches were treated with about 64 short implants with minimum insertion torque value of 20 Nc, the implant and prosthetic survival rates were 100%. Eight patients were restored with permanent hybrid fixed zirconia or acrylic resin prostheses. Two patients were restored with titanium bar frameworks and removable overdentures. No prosthetic complications were reported for the definitive prostheses. However, these results should be interpreted with caution. In contrast, [PERSON] et al. [23] used full-arch screw-retained fixed restorations and found only screw loosening during the 1 year follow-up. The restorative failures most reported by the author were loosening, loss of retention, rod adjustment, rod tension, cantilevers, and relining. In an interesting systematic review conducted by [PERSON] et al. [40], satisfactory clinical and aesthetic results were found for full-arch implant restoration using monolithic zirconia, thus increasing short-term success. To date, the rate of technical complications associated with this type of restoration is still minimal, and survival rates are very high. As the concept of short implants remains an evolving abstraction (less than or equal to 8 mm), two different calculations were performed in this review--(1) \(\leq\)9 mm and (2) \(\leq\)5 mm--as a threshold for short length implants.