Purpose: The aim of this study was to evaluate the survival and success rates of oral rehabilitations in a shortened maxillary dental arch and expanded maxillary sinus with 4-mm extrashort implants splinted to longer ones.

Materials and methods: One 10-mm and one/two extrashort 4-mm titanium-zirconium SLActive tissue-level dental implants were inserted into 11 patients with limited vertical bone availability due to an expanded maxillary sinus antrum. Immediately and 6 months after insertion, implant stability resonance frequency analysis (RFA) values were assessed with an Osstell device. Splinted crowns combining 4- and 10-mm implants were supplied to all 11 cases.

Results: In 10 cases, the bone quality was type III, and in one case, type IV. Among 17 4-mm and 11 10-mm implants, the median RFA values were 61 (interquartile ranges [IQR]: 59 to 64) and 66 (IQR: 64 to 72). One 4-mm implant failed to osseointegrate and was removed. After 6 months of healing, secondary-stability measurements of 16 of the remaining 4-mm implants increased to 68 (IQR: 62 to 72) and of 10-mm implants to 78 (IQR: 77 to 80). After 1 year, all (11/11) oral rehabilitations supported by 10-mm (11/11) and 4-mm (16/16) implants were functional. The medians and IQRs of the probing depths (median: 2.8 mm, IQR: 2.3 to 3.1 mm vs median: 2.9 mm, IQR: 2.4 to 3.1 mm) and the crestal bone loss (median: 0.75 mm, IQR: 0 to 0.9 mm vs median: 0.22 mm, IQR: 0 to 0.4 mm) for the 10-mm and 4-mm implants, respectively, were similar.

Conclusion: Rehabilitations with splinted crowns combining 4- and 10-mm implants demonstrated a favorable 1-year performance in a shortened maxillary dental arch.