Consecutive unsplinted implant-supported restorations to replace lost multiple adjacent posterior teeth: A 4-year prospective cohort study

Objective. The aim of this study was to investigate the various events occurring in unsplinted implant restoration in posterior jaws during a period of 4 years. Materials and methods. From August 2008 to April 2009, eight volunteers (three men and five women) who had two or more consecutively missing teeth received 20 implants in posterior maxillae and mandibles. Unsplinted single crowns were delivered to each implant. For the 4-year follow-up periods, patients were enrolled in a maintenance schedule at 1, 3, 6, 12, 24, 36 and 48 months. The data, including a questionnaire, radiography, mobility and probing were recorded on regular check-ups. Results. A total of 20 implants in eight patients were followed up for 48 months, showing a 100% survival rate. Mean marginal bone loss around implants was 0.26 mm. Statistical analysis revealed insignificant correlation between metal-ceramic and zirconia-ceramic crowns and among implant lengths (8.5 mm, 10 mm and 11.5 mm). Mean probing depths were similar or insignificantly different, regardless of the materials used or length of implants. The most frequent complications, in decreasing order, were food impaction (65%) and porcelain chipping (45%), sensitivity (25%), pain (20%) and loose contact (15%). Compared with metal-ceramic crowns, zirconia-ceramic crowns showed more unfavorable cases of porcelain chipping (p = 0.017), pain (p = 0.007) and loose contact with an adjacent crown (p = 0.031). Conclusions. Within the limits of the sample size, this study showed that unsplinted implant-supported single restorations to replace consecutive posterior missing teeth may function well.