## 4 Discussion
At bone level it is assumed to be incorporated into the bone matrix and to be involved in calcium binding [35]. It is a major non-collagenous protein of the dentine matrix and is regarded as a reparative molecule, expressed as a response to an offence of the dental pulp. Osteocalcin is regarded as a late differentiation marker of odontoblasts [29; 36]. Our results are similar to those reported by [PERSON] et al. [29], who measured osteoclast levels in dental pulp using a multiplex assay and found significantly higher levels (\(p<0.05\)) of this protein in irreversibly inflamed human dental pulps compared to healthy pulp samples. Cells that are dominant in inflamed dental pulps, such as macrophages, may express osteoclastin in their transdifferentiation to osteoblasts [29]. These findings may indicate that large amounts of osteoclastin are secreted from odontoblasts to form the predentin of reactionary dentin in response to the pulp inflammation [37]. However, it can be speculated that the elevated expression of other inflammation biomarkers impedes the limitation of inflammation and the reactionary dentinogenesis initiation. Transforming growth factor-beta (TGF-\(\beta\)1) is produced by odontoblasts in normal pulps, and promotes matrix metalloproteinase secretion and dentin mineralization, playing an important role in dentinogenesis and repair. TGF-\(\beta\) molecules have mitogenic effects and chemotactic properties for fibroblasts, macrophages, neutrophils, and monocytes [38]. In vivo studies showed that the use of TGF-\(\beta\)1 in wound areas may expand the synthesis of ECM proteins [39; 40]. Our results are in accordance with those of previous studies, reporting a significantly higher TGF-\(\beta\)1 expression in irreversibly inflamed dental pulps [41; 42]. In vitro studies reported a downregulation of TGF-\(\beta\)1 gene expression [43]. TGF-\(\beta\)1 can also increase the local predentin secretion [44]. The role of TGF-\(\beta\) in dentinogenesis could be attributed to its involvement in odontoblast differentiation [45], and other activities mentioned above; it may take part in reparative processes by regulating cell proliferation, migration, and ECM production in dental pulp [46]. Catalase is also an enzyme (like SOD3) that scavenges hydrogen peroxide released during, both, normal aerobic and pathogenic metabolism (inflammation) from host cells [47]. In our study, the determination of catalase levels in irreversibly inflamed and healthy dental pulp samples showed non-significant differences (\(p=0.064\)). [PERSON] et al. [48] also evaluated catalase activity in irreversibly inflamed and healthy pulp samples. Their study showed a significant increase (\(p<0.001\)) in the inflamed pulp tissues in comparison to the controls. The differences between our results and the reports of [PERSON] et al. [48], may be caused by the different manner in which catalase's presence was determined in dental pulp samples: our study used the ELISA technique for the determination of protein expression, while [PERSON] et al. [48] evaluated catalase activity using spectrophotometric methods. MMPs are zinc-dependent proteases with endopeptidase activity, which can degrade ECM, contributing to the inflammation pathogenesis [49]. MMPs play an important role in physiological and pathological conditions, such as pulpal and periapical tissue destruction caused by inflammation, and wound healing [11; 49]. These enzymes can be upregulated in different pathologies, such as inflammation [11; 49]. MMP-7, or matrilysin, has the ability to cleave entactin, a basement membrane protein, which links laminin and collagen type IV, triggering the basement membrane disruption [50]. To the best of our knowledge, there are no studies regarding MMP-7 levels in healthy versus inflamed dental pulp in humans, however, significantly elevated mRNA levels and protein expression of MMP-7 were found in inflammatory lesion tissue samples of chronic apical abscesses, as compared to control samples of healthy periodontal ligament tissue.