Short (5 and 7mm long) porous implants in the posterior atrophic maxilla: a 5-year report of a prospective single-cohort study

Purpose: The aim of this ongoing prospective study was to determine the 5-year survival rate of short porous dental implants in the posterior atrophic maxilla combined, when necessary, with crestal sinus floor elevation and often adding anorganic bovine bone. Materials and methods: In 87 partially edentulous patients, 110 short porous implants were placed and followed up for 5 years. The implants used were of two lengths (5 and 7 mm) and two diameters (4.1 and 5 mm) and were chosen according to the available crestal height and width. In 47 sites, osteotome sinus floor elevation was performed (in 8 cases compacting basal bone, in 39 adding a xenograft). The unloaded healing period was 6 months. A total of 63 implants were restored with single crowns and 47 were splinted to the adjacent implants. Outcome measures were prosthesis and implant failures, any complications, and peri-implant marginal bone resorption. Results: Five years after loading, no patients dropped out. Eleven implants failed: 2 implants at uncovering and 9 after prosthetic loading. Eleven patients (12.6%) lost 1 implant. In 6 patients (6.9%) a prosthesis failure occurred (implants loaded with single crowns). One surgical complication (membrane perforation) occurred but the implant was normally inserted. No complications occurred during the healing period. In 3 patients, severe peri-implantitis occurred post loading and the implants had to be removed. Two abutments became loose and one crown chipped. At the end of the follow-up period the implant survival rate was 90%, and 93.1% with regard to prosthetic reconstruction. The mean peri-implant marginal bone loss was 1.4 mm. Conclusions: The use of short porous implants showed an acceptable clinical outcome in the treatment of the posterior maxilla in this interim 5-year report. Longer follow-ups are needed to confirm these results. Keywords: deproteinised bovine bone, implant prosthesis, osteotome sinus elevation, posterior maxilla, short dental implants