Advances in the application of photodynamic therapy to root canal disinfection / 口腔疾病防治

@#In recent years, many researchers have devoted themselves to the application of photodynamic therapy (PDT) in root canal disinfection, as conventional root canal disinfection methods have failed to achieve the optimal effect. Some clinicians have also applied PDT to root canal disinfection. PDT is expected to have a better effect than traditional root canal disinfection. This paper reviews the research progress on the mechanism, effect, influencing factors and limitations of PDT in root canal disinfection. Current research suggests that differences in the type and status of the bacteria, photosensitizers, light sources, operating environment and methods all affect the efficacy of root canal disinfection of PDT. Most of the research into PDT for root canal disinfection finds that it is effective, nontoxic, advantageous to dental pulp regeneration and comfortable for the patient, as well as lacking an excitant; however, its bactericidal effect is inferior to that of sodium hypochlorite. At present, it cannot replace traditional chemical washing but is a promising auxiliary method. The design of the photosensitizer, the energy dose of the light source and the optimal irradiation time need to be determined by further experiments, and more clinical verification is needed before its application in root canal therapy.

The role of APOD in the proliferation and migration of human dental pulp cells / 口腔疾病防治

Objective@#To explore the role of apoliprotein D (APOD) in the proliferation and migration of human dental pulp cells (DPCs) and to provide a basis for the use of APOD to promote pulp regeneration. @*Methods@#APOD expression in human dental pulp cells was inhibited by siRNA. The inhibition effect of APOD was confirmed by qPCR and Western blot. After APOD inhibition, colony formation experiments and CCK8 assays were employed to confirm the proliferation ability of dental pulp cells. Transwell assays were used to verify the cell migration ability after the inhibition of APOD expression.@*Results @# After inhibiting APOD expression, the colony formation rate in the si-apod group was reduced compared with the NC group, and the difference was statistically significant (t=7.624, P=0.002). The CCK8 experiment showed that the OD value in the si-apod group decreased at 3, 5 and 7 d compared with that in the NC group (P < 0.05). Transwell results showed that the number of cell divisions was 57.25 ± 4.03 in the si-apod group and 154.50 ± 8.39 in the NC group, and the difference was statistically significant (t=10.45, P < 0.001).@*Conclusion@# Inhibition of APOD expression in dental pulp cells inhibits their proliferation and migration ability.

The effects of leptin on osteogenesis/odontogenic related gene expression of human apical papillary stem cells / 口腔疾病防治

Objective@#To investigate the effects of leptin on the proliferation of stem cells from human stem cells from the apical papilla (hSCAPs) and the expression of osteogenic/dentinogenic genes in vitro to provide an experimental basis for the sustainable development of young permanent teeth. @* Methods @#The tissue block method was used to isolate and culture hSCAPs from the apical papilla of the immature third permanent molar. The expression of leptin and OBRb in hSCAPs was detected using immunocytofluorescence staining, western blotting and reverse transcription polymerase chain reaction (RT-PCR) analysis. The hSCAPs was treated with 0.1 μg/mL of leptin (0.1 μg/mL group) or 1.5 μg/mL of leptin (1.5 μg/mL group) at different time points. The control group was treated with alpha-MEM medium. Cell proliferation was measured using the CCK8 assay and cell cycle analysis. QRT-PCR was used to detect the expression of related osteoblast/odontogenic genes for alkaline phosphatase (ALP), dentin matrix protein -1 (DMP-1), dentin sialophosphoprotein (DSPP), and osteocalcin (OCN) mRNA. The differences between the treatment groups and the control group were analyzed statistically using one-way ANOVA followed by Bonferroni analysis.@*Results@#The expression of both leptin and OBRb were found in hSCAPs. Compared with the control group, the cell proliferation capacity and S phase cells in the treatment groups were higher than those in the control group, with the 1.5 μg /mL group displaying higher levels than 0.1 μg /mL group, and the treated hSCAPs demonstrated a higher proliferation rate and a higher expression of ALP, DSPP, and DMP-1 from day 3 to day 7, with the 1.5 μg /mL group displaying higher levels than 0.1 μg /mL group , and the difference was statistically significant (P < 0.05), at day 7. The treated hSCAPs demonstrated a lower expression of ALP, DSPP, and DMP-1. Compared with the control group, the treated hSCAPs demonstrated a higher expression of OCN from day 7 to day 14, with significantly higher expression in the 1.5 μg /mL group compared to the 0.1 μg /mL group.@*Conclusion@#Leptin may promote cell proliferation and upregulate the expression of relative osteogenic/dentinogenic genes.

CBCT detection of the incidence of middle mesial canal and isthmus in the mandibular first molar / 口腔疾病防治

Objective @# To analyze the morphology and incidence of middle mesial canal (MM) and isthmus in the mandibular first permanent molar by cone-beam computed tomography (CBCT).@*Methods@# Statistical analysis was performed on images from patients who underwent CBCT examination in the Department of Radiology at Stomatological Hospital, Southern Medical University. Samples exhibiting root canal treatment, root resorption and calcification were excluded. Data regarding sex, age, the presence or absence of isthmus and MM, and the number of roots and root canals were recorded.@*Results @#Of the 217 mandibular first molar samples, 8 (3.7%) had an MM, and 2 (0.9%) had an independent apical foramen. The overall incidence rate of isthmus was 57.1%; this rate was 50.7% in the cervical third of the root canal, 17.5% in the middle third, and 13.4% in the apical third. The incidence rate of isthmus was 61.8% on the left side, 52.3% on the right side, 58.7% in males, and 55.8% in females. No significant difference was found between the left and right sides or between females and males (P > 0.05). The incidence rate of isthmus in people under 60 was greater than 50% but was significantly lower in people older than 60.@*Conclusion@#Only a very small proportion of MMs have an independent apical foramen in the mandibular first molar. The incidence of isthmus in the mesial root of the mandibular first permanent molar is high, and isthmus usually occurs in the cervical third of the root canal. During root canal treatment or apical surgery, attention should be given to the physical and chemical preparation of the isthmus.

Locations of TLR4 in healthy dental pulp tissue and dental pulp tissue affected by deep caries / 口腔疾病防治

Objective@#To analyze the role of TLR4 in innate immune response of dental pulp by comparing the locations and expressions of TLR4 in healthy dental pulp tissue and dental pulp tissue affected by deep caries. @*Methods @# Healthy teeth and teeth affected by deep caries were demineralized and stained with hematoxylin and eosin (HE) to observe the morphology of dental pulp. Immunohistochemistry staining was performed to observe the expressions of TLR4.@*Results @# Observed under HE staining, dentin tubules of teeth affected by deep caries were damaged with a lot bacteria mass. The expression of TLR4 were located in the odontoblast layer and near the blood vessels in both groups. Positive staining of TLR4 in deep caries pulps (2.10±0.74) were significantly higher than that in healthy teeth (1.25 ±0.46). @*Conclusion @#Expression of TLR4 in deep caries pulp is stronger than that in healthy pulp. It suggests that TLR4 may play a role in the innate immune response of deep caries.