Nine studies were included (n=243): five randomised controlled trials (n=168) and four controlled trials (n=75). Five of the studies included comparisons of loading times (three randomised controlled trials, n=92 and two controlled trials, n=41) Only one randomised controlled trial clearly concealed treatment allocation. No type of blinding was reported in any study. The follow up rate was over 80 per cent in all studies.
Immediate versus conventional loading (one randomised controlled trial):
No statistically significant difference between the groups was found for any outcome at 12 or 24 months.
Early versus conventional loading (two randomised controlled trial and one controlled trial):
Results for probing depth at 24 months significantly favoured the conventional group (weighted mean difference 0.26, 0.04, 0.48, p=0.02, two randomised controlled trials, n=72). No other significant differences were found between the groups at 12 or 24 months. No significant heterogeneity was reported for any outcome.
The review also summarised before-and-after data from studies conducted at a single loading time.