A prospective study by Rossi et al published in Clinical Oral Implants Research evaluated clinical and radiographic outcomes of 6- or 10-mm long implants loaded within 7 weeks from installation. The implant-supported single crowns in the posterior regions were evaluated in the course of 5 years of loading. The study involved 60 implants with a moderately rough surface; 30 tests and 30 controls (all were 10-mm long, 4.1-mm in diameter) were placed in posterior regions in 45 patients. After 6 weeks, impressions were taken and the implants were restored with a single fixed prosthesis made with gold-palladium alloy and porcelain. Survival rate and marginal bone loss were evaluated yearly. The clinical crown-implant ratio was calculated. During the follow-up period, 5 implants (4 tests and one control) were lost. Of the 4 test implants, one was lost before loading, 2 between the second and the third years, and one during the fourth year of the follow-up period. The control implant was lost during the first year of function. Consequently, after 5 years of follow-up, a survival rate of 86.7% and 96.7% was observed at the test and control sites, respectively. The results of this study showed that 6-mm long implant-supporting single crowns loaded within 7 weeks from installation lose a small amount of marginal bone during 5 years of functional loading, similar to that of 10-mm long implants. However, a higher degree of implant loss was recorded at the short implants, probably due to the fracturing of the surrounding bone.
(Source: Clinical Oral Implants Research, April 2015, Volume 26, Issue 4)