Specific signaling molecule expressions in the interradicular septum in different age groups

Orthodontic teeth movement is accompanied by the remodeling of alveolar bone, including the interradicular septum. Bone contains three cell types, osteoblasts, osteocytes, and osteoclasts that are in direct contact with all of the cellular elements in the bone marrow. Marrow is the source of both bone-building osteoblasts and bone destroying osteoclasts, and the turnover of bone occurs throughout life. Bone signalling molecules have important functions during osteogenesis, and they are active in the bone remodelling process. Patients involved in orthodontic treatment belong to different age groups: therefore age must be considered as a contributing factor compromising the osteogenetic potential of bone. The aim of the current study was to investigate the specific expression of signalling molecules in the interradicular septum in different age groups.

The study group included 17 patients to whom the extraction of teeth was recommended as part of further orthodontic treatment. Patients (9 males and 8 females) - were divided into 3 groups 1st group - 12-14 years old); 2nd group - 15-22 years old; 3rd group - 23 years old or older. Expression of BMP 2/4, TGF-α, IL-1, IL-8, OPG, MMP-1, MMP-2, MMP-8, MMP-9, MMP-13, NGFR, NKpB 105, osteocalcin, and osteopontin in interradicular septum tissues was examined. TUNEL staining was also completed. The distribution of these factors was evaluated semi quantitalively.

In the interradicular septum bone structure, the expression levels of osteocalcin, osteoprotegerin, matrix metalloproteinases 8 and 9, and nuclear factor kappa B were determined in all samples. TUNEL staining was also done. Age related decreases in the mean values of signalling factors and the number of apoptotic cells were statistically significant.

Specific to interradicular septum osteoblasts and osteoclasts factors include osteoprotegerin, osteocalcin, matrix metalloproteinase 8, matrix metallproteniase 9, and nuclear factors kappa B. The mean expression levels of these proteins and the mean TUNEL staining statistically significantly decreased with age. This is preliminary study and more patients are necessary for more precise statistical analysis in the future.