Introduction: Rapid maxillary expansion (RME) is a remarkable and ideal procedure which has a long history of over 100
years. When a transverse maxillary Arch is diagnosed it is treated by doing RME. Although numerous studies have been done in last
four decades on gingival crevicular fluid, no data have been reported on the repeatability of gingival crevicular fluid collection and
then following its quantification procedure. The objectives of the study were to observe the changes in alkaline phosphatase (ALP)
activities in gingival crevicular fluid (GCF) during rapid maxillary expansion and particularly in retention period and then explore
the relationship between these changes and periodontal tissue remodeling.
Methodology: Seventeen patients with age between 9-14 years were selected according to inclusion and exclusion criteria
of our study. Periodontal parameters, including probing depth, were recorded at 3 months after RME. Furthermore, the GCF ALP
activity was measured at the buccal and palatal sites.
Results: Periodontal parameters were generally similar between the Testing and Control sites during the study, with the
exception that probing depth underwent a slight increase at the Testing sites. It was observed that at baseline, the GCF ALP activity
was similar between the buccal and Control sites; however, at 3 months of retention period a considerably increased enzymatic
activity was seen at the Testing sites.
Conclusion: The results of our study concluded that in the retention phase of RME, there is reported increased GCF ALP activity
observed even at the end of 3 months of retention period with no clinically considerable tissue inflammation. This increase in GCF
ALP activity suggests a longer period of retention phase after maxillary expansion may be up to 6 months of duration.