Human closed and open apex premolar teeth express different toll-like receptor

The innate immune activation which promotes inflammation responses in the dental pulp tissue leads to the progression of dentin caries. Accordingly, toll-like receptors (TLRs) are key molecules of the innate immune system that identify pathogen-associated molecular patterns (PAMPs) on microorganisms and may have a critical role in a dental injury. Therefore, this study aimed to investigate the expression of TLR2, TLR3, and TLR4 in the human dental pulp of opened and closed apex teeth.

Human dental pulps were derived from the healthy opened and closed apex premolar, in which extraction was indicated for orthodontic reasons. The extraction of RNA was performed and the gene expression determined by real-time polymerase chain reaction (RT-PCR). The result from real-time PCR was confirmed using western blot analysis.

Real-time PCR data analysis showed that the expression TLR2 and TLR4 were significantly increased in closed apex premolar teeth compared to open apex teeth, whereas TLR3 expression was not significantly different in these two groups (p < .05).

The results of the present study suggested increased expression of TLR2 and TLR4 by the maturation of the apex, which may be due to the presence of microorganisms in the normal or destructed dental pulp tissue. Thus, identifying the expression of TLRs molecules in dental pulp tissue helps to develop a deeper knowledge of the immune responses in the oral cavity.