IADR Abstract Archives
The Molecular Mechanism Underlying Orthodontic Relapse
Objectives: Orthodontic tooth relapse (OTR) is an undesirable outcome of orthodontic treatment. Recent studies demonstrated the crucial role of the immune system in orthodontic tooth movement (OTM). However, whether this mechanism regulates OTR is still unclear. Here, we aimed to investigate the role of the innate and adaptive immune response during OTR using in vivo time-course gene expression profiling.
Methods: The OTR model included two steps: first, initiating OTM and then allowing the mice's teeth to relapse. To initiate OTM, Ni-Ti springs were set between upper left first molars and upper incisors of C57BL/6 mice. Following 14 days, springs were removed and the molars were allowed to relapse for 0,1,7,14 days. To validate the OTR model, we measured relapse rate by Micro-CT (n=6\group). To investigate gene expression profiles, the periodontal tissue blocks were extracted and RNA sequencing was performed (n=5\group). Gene function was inferred by Gene Set Enrichment Analysis (GSEA). The K-means algorithm and pathway analysis method were used to identify gene clusters in a time-course manner. qRT-PCR was used to validate genes of interest (n=7\group).
Results: Micro-CT analysis showed a OTR rate of 50%,57%,59.9% following 1,7 and 14 days, respectively, compared to 0% in the control group (0-day relapse). A total of 605 differentially expressed genes (DEGs) were identified over the OTR period with the highest number (514) at day-7. GSEA in day-1 showed an upregulation of genes related to collagen biosynthesis, cartilage development, osteoclast differentiation, angiogenesis, inflammatory response, and TNF-α signaling. Day-7 showed an upregulation in genes related to the innate-adaptive immune system, antigen processing, and cytokine signaling. qRT-PCR results showed that over the relapse period there was an upregulation in the innate and adaptive immune cells such as neutrophils, macrophages, T cells, and B cells validating RNA sequencing results.
Conclusions: This is the first in vivo report of gene expression signatures of OTR in a time-dependent manner. The gene sets found constitute attractive targets for future molecular basic science studies in the orthodontic field and will contribute to finding novel therapeutic means to clinically control it.
Methods: The OTR model included two steps: first, initiating OTM and then allowing the mice's teeth to relapse. To initiate OTM, Ni-Ti springs were set between upper left first molars and upper incisors of C57BL/6 mice. Following 14 days, springs were removed and the molars were allowed to relapse for 0,1,7,14 days. To validate the OTR model, we measured relapse rate by Micro-CT (n=6\group). To investigate gene expression profiles, the periodontal tissue blocks were extracted and RNA sequencing was performed (n=5\group). Gene function was inferred by Gene Set Enrichment Analysis (GSEA). The K-means algorithm and pathway analysis method were used to identify gene clusters in a time-course manner. qRT-PCR was used to validate genes of interest (n=7\group).
Results: Micro-CT analysis showed a OTR rate of 50%,57%,59.9% following 1,7 and 14 days, respectively, compared to 0% in the control group (0-day relapse). A total of 605 differentially expressed genes (DEGs) were identified over the OTR period with the highest number (514) at day-7. GSEA in day-1 showed an upregulation of genes related to collagen biosynthesis, cartilage development, osteoclast differentiation, angiogenesis, inflammatory response, and TNF-α signaling. Day-7 showed an upregulation in genes related to the innate-adaptive immune system, antigen processing, and cytokine signaling. qRT-PCR results showed that over the relapse period there was an upregulation in the innate and adaptive immune cells such as neutrophils, macrophages, T cells, and B cells validating RNA sequencing results.
Conclusions: This is the first in vivo report of gene expression signatures of OTR in a time-dependent manner. The gene sets found constitute attractive targets for future molecular basic science studies in the orthodontic field and will contribute to finding novel therapeutic means to clinically control it.