Evaluation and Correlation of Salivary Bone-Specific Alkaline Phosphatase Level with Skeletal Age

This study aimed to measure bone-specific alkaline phosphatase (B-ALP) levels in saliva and determine how they relate to different stages of skeletal development, as assessed by hand-wrist X-rays using the Hagg and Taranger method. Since orthodontic treatment is closely linked to an individual’s growth, the development of the jaws, face, and overall body, and how they affect the alignment of teeth, the suggestion to use biomarkers to evaluate an individual’s skeletal maturity has emerged as a promising approach. Unlike traditional radiographic methods, which are subjective and based on morphology, biomarkers provide objective indicators related to the patient’s physiology, and they do not involve radiation exposure or magnification errors. The main goal of this study was to measure B-ALP levels in saliva and examine their correlation with varying degrees of skeletal maturity. In a positive correlation, the total ALP present in saliva could be a valuable biological indicator in growing patients.

Thirty patients were randomly selected for the study based on the inclusion criteria: Age of the individual: 9‒19 years, with good general health and no nutritional issues. A sample of unstimulated whole saliva was collected using a passive drooling method to estimate levels of the bone alkaline phosphatase using an enzyme-linked immunosorbent assay (ELISA) kit. After saliva collection, hand-wrist radiographs were immediately obtained and manually traced onto 50-micron-thick lead acetate tracing sheets using an 0.5-mm lead pencil. The hand-wrist radiographs were then categorized into five groups, which involved analyzing the morphology of the hand-wrist radiographs: group SO (prepubertal), group S (pubertal onset), group MP3G (peak pubertal), group DP3 (pubertal deceleration), and group RJ (growth completion).

There were significant differences between the B-ALP levels between different skeletal ages. The salivary B-ALP values of the group MP3 were significantly higher than those of groups SO and RJ. The mean salivary B-ALP levels consistently increased from the group SO to the group MP3, followed by a gradual decrease.

Salivary alkaline phosphatase activity was significantly higher during the peak pubertal period (group MP3) compared to both the pre-peak (group SO) and post-peak (group RJ) values. This finding suggests that salivary bone alkaline phosphatase can be used as an additional indicator alongside conventional skeletal maturation indicators to assess pubertal development.