Total flapless split-crest technique with tunnel connective graft using microspire conical connection implants: a 3-year retrospective study

Introduction During fixed implant-prosthetic rehabilitation of the jaw there is often an alveolar bone volume that is not suitable for a correct and prosthetically guided insertion of the implant. In horizontal bone defects, the split crest technique with concomitant insertion of the implant fixture has proved to be a valid solution for the management of atrophy in cases of bone thickness of 3 mm or more. The total-flapless technique seems to significantly reduce bone resorption following the split crest even in cases of a high degree of horizontal atrophy, between 1.5 and 3mm, in which more significant volumetric increases are required. In addition, the insertion of a switching-platform implant associated with a supracrestal soft tissue tickness greater than 2mm seems to ensure a lower risk of gingival recession and bone loss around implants in medium and long term.

Materials and MethodsIn the present study, 23 patients underwent a total flapless split crest surgery with contextual insertion of 37 implants sometimes associated with soft tissue augmentation procedure. All patients showed pre-operative horizontal dimension of the alveolar ridge in its most coronal portion between 1.5 mm and 3 mm. For each of the 37 implants included in this study, crestal bone thickness was assessed before surgery (T0), 6 months after surgery (T1) and 3 years later (T2) by CBCT.

Results Six months after surgery (T1) the horizontal bone volume increased and varied in a range between 3.5mm and 4mm, with an average value of 3.8mm (DS 0.20mm). Three years after surgery (T2) was possible to observe a very low vertical loss of bone around implants. Overall implant survival rate was 100% and no cortical fractures were detected during cortical expansion. The transmucosal path was stable and free from periodontal recessions.

Conclusions The use of a total flapless bone expansion technique allows to minimize the surgical trauma and to avoid the use of sutures. In addition, the blood circulation between the bone and the periosteum should be fully preserved with a decrease of post-surgical vertical bone resorption in the augmentation area. The simultaneous insertion of a platform switching implant with conical connection seems to improve the maintenance of bone peaks in the first 3 years after surgery if original trans-gingival path is of at least 2mm. The technique is characterized by reduced visibility. Therefore a correct pre-surgical digital planning and a long learning curve make this approach highly operator dependent.