###### Abstract  
The aim of this study was to investigate the levels of bone alkaline phosphatase (BALP) and osteoclastcin (OC) in the saliva of growing patients of different maturation levels. The sample consisted of 55 patients (34 females and 21 males of 7-16 years old). Two milliliters of saliva were collected and BALP and OC levels were assessed. Skeletal age was estimated using the cervical vertebral maturation method (CVM). The relationship between the biomarkers' concentration in saliva and skeletal age was examined with the Spearman's coefficient \"\(\rho\)\" (rho). Correlations between skeletal age groups and BALP and OC concentrations were assessed with the Kruskal-Wallis or the Mann-Whitney tests. No statistically significant differences in the levels of BALP (\(p\) = 0.568) and OC (\(p\) = 0.996) in saliva were identified according to the patient's skeletal age. The use of BALP and OC levels in saliva seems to be dubious for skeletal growth assessment. However, slightly differentiated levels of those biomarkers, especially of BALP, through the different maturation stages, with higher concentrations at the pubertal phase, have been noticed. More studies are needed to clarify the exact potential role of these biomarkers as predictors of pubertal onset.  
saliva; bone alkaline phosphatase; osteoclastcin; cervical vertebral maturation (CVM); growth phase +
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protein biomarkers [6]. In general, biomarkers can exist in various forms, such as DNA, RNA, metabolites, lipids, and proteins. Alterations in structure, function, or concentration can be linked with the onset of a disease or with the progression or regression of a disorder. Evaluating and understanding the importance of an individual's biomarkers can be helpful in the definition of the presence, location, or even the potential of a disease.  
Alkaline phosphatase is a membrane-bound glycoprotein [7], which has been found to be one of the primary biomarkers in the process of osteogenesis [8]. Bone alkaline phosphatase (BALP) is the bone-specific isoform of alkaline phosphatase and has been found to be a bone metabolism marker with high reliability [9]. BALP levels or activity have been linked with saliva, suggesting that salivary BALP could be considered a valuable diagnostic tool for growth spurt assessment, even though the results have been contradictory up until now [10; 11].  
Osteocalcin (OC) is a bone-specific protein synthesized by osteoblasts that can be found in dentin and bone [12] and plays a significant role in bone resorption and mineralization [13; 14]. OC is a biomarker of late osteoblast differentiation [14]. The serum OC was found to increase in specific conditions, such as osteoporosis, which demands higher rhythms of bone turnover [15]. Moreover, OC levels have been linked with skeletal growth in puberty [16]. In saliva, OC levels have been examined as a biomarker of bone loss in periodontal studies [17], as well as in studies focusing on smoking [18]. OC levels have been assessed and compared with cervical vertebral maturation index stages by blood/serum examination [19].  
To date, only a few studies with contradictory findings have investigated the levels of BALP in saliva [10; 11; 20; 21; 22; 23], and the exact role of BALP is not well documented and needs to be addressed. Moreover, according to our knowledge, no published studies have investigated salivary OC levels in relation to skeletal growth. In light of the above, further research is required to detect if there is any relationship between BALP and OC levels in saliva and growth.  
The aim of this study was to investigate the levels of BALP and OC in the saliva of growing patients and to find possible alterations in the levels of those biomarkers among different pubertal stages.