Alkaline phosphatase level in gingival crevicular fluid during treatment with Quad-Helix

The aim of this work is to assess the level of the human alkaline phosphatase enzyme (ALP) during palatal expansion with Quad-Helix (QH) appliance. A total of twenty-two orthodontic patients characterized by contraction of the upper jaw, that needed application of a QH in order to treat their condition, were included in this study. Gingival crevicular fluid (GCF) was collected at four different times: before cementation (T0), after two weeks (T1), after four weeks (T2) and after one year (T3) from application of QH. In each patient maxillary first molars, right (UM-right) and left (UM-left), which were connected with bands to QH, were used for testing; first lower molars were used as Controls (LM-right, LM-left). Data show that ALP level in tension sites was proportional to the average increase of the inter-molar distance; on the contrary, the enzymatic level in compression sites was characterized by an inverse trend. The only exception to this phenomenon was recorded after one year (T3), when the increase of ALP level in both sites of tension and compression was ascribed to a mild inflammation due to bacterial plaque accumulation. The level of ALP in control sites was constant for the whole period of observation. The described ALP fluctuations in accordance with the inter-molar distance increment, shows that the main action of QH on bone remodelling was exerted during the fourth week (T2); for this reason, the monitoring of this enzyme could be used as a marker of effective function of the QH appliance.