The sandwich osteotomy technique to treat vertical alveolar bone defects prior to implant placement: a systematic review.

The aim of this systematic review was to investigate the predictability of the sandwich osteotomy technique to provide sufficient alveolar bone height for dental implant therapy in vertically atrophic jaws. A MEDLINE (Pubmed), EMBASE and Cochrane Library electronic search and a manual search were performed until July 2018. Any clinical study published in English, reporting data on at least 10 patients rehabilitated with implant-supported dental prostheses after vertical ridge augmentation by means of the sandwich osteotomy technique and followed for at least 12 months after loading, was included. Data on study and patients' characteristics, interventions provided, implant and prostheses survival rates and complications were extracted from the included studies. Each study design was evaluated using the Cochrane Collaboration's tool for assessing risk of bias. Initially, 415 records were identified, from which 10 full-text articles could be included in the final qualitative analysis. Implant survival rate after a mean follow-up of 3.7 years (median: 3 years; range: 1-7 years) was 94% (median: 93%; range: 91-100%). Peri-implant mean marginal bone resorption was 1.6 mm (median: 1.4 mm; range: 0.6-4.7 mm). The calculated mean alveolar bone height available at the time of implant placement was 11.3 mm (median: 11.5 mm; range: 7.8-16 mm). A temporary sensory disturbance of the inferior alveolar nerve was the most commonly reported complication following the sandwich osteotomy. The present systematic review documents that implant survival rate after mandibular vertical ridge augmentation using the sandwich osteotomy technique is high after up to 5 years of loading. The complication rate can be considered moderate and has predominantly a transient nature. Data on the long-term behavior of the augmented bone and inserted implants are missing. The present technique can be considered a reliable treatment option in cases of moderate vertical bone deficiency of the posterior mandible to provide suitable conditions for later implant placement. Intra- and post-operative complications do not seem to jeopardize the final outcome.