[Evaluation on the fracture resistance of dental tissues after guided plate-mediated precision minimally invasive root canal treatment].

PURPOSE: In order to achieve accurate and minimally invasive root canal treatment and enhance the fracture resistance of tooth tissue after root canal therapy, this study explores digital guided mediated minimally invasive root canal treatment and compares it with conventional root canal treatment to provide a more favorable method for clinical practice. METHODS: Forty freshly extracted first permanent molars were randomly divided into control group and experimental group. Teeth in the control group were treated with conventional root canal treatment, while teeth in the experimental group were treated with precise minimally invasive root canal treatment. The difference between the time of opening of the pulp chamber and the area of the open pores on the total area of the occlusal surface was compared. Loading test was carried out on the subjects using a universal testing machine, and the fracture resistence of the tooth tissues of the two groups were measured. Statistical analysis was performed using SPSS 24.0 software package. RESULTS: In the control group, the time required for opening the pulp chamber was (1.85±0.05) min, the open pore area was (9.18±0.48)% of the total occlusal area, and the load of the tooth tissue was (1.48±0.07) kN. In the experimental group, the time required was (0.72±0.10) min, the open pore area was (3.53±0.13)% of the total occlusal area, and the load of the tooth tissue was (1.81±0.03) kN. The higher the loading value, the stronger the fracture resistance of the tooth tissue. Compared with traditional root canal treatment, digital guided plate mediated minimally invasive root canal treatment had the advantages of short time, small access cavity and strong fracture resistance of tooth tissue. The difference between the two groups was significant (P<0.01). CONCLUSIONS: Digital guided plate-mediated accurate minimally invasive root canal treatment can reduce the occlusal area, shorten the operation time beside the chair, retain more healthy tooth tissue, enhance the fracture resistance of tooth tissue after root canal treatment, and improve the retention rate of affected teeth.

A novel vaccine delivery system: biodegradable nanoparticles in thermosensitive hydrogel.

In this work, a novel vaccine delivery system, biodegradable nanoparticles (NPs) in thermosensitive hydrogel, was investigated. Human basic fibroblast growth factor (bFGF)-loaded NPs (bFGF-NPs) were prepared, and then bFGF-NPs were incorporated into thermosensitive hydrogel to form bFGF-NPs in a hydrogel composite (bFGF-NPs/hydrogel). bFGF-NPs/hydrogel was an injectable sol at ambient temperature, but was converted into a non-flowing gel at body temperature. The in vitro release profile showed that bFGF could be released from bFGF-NPs or bFGF-NPs/hydrogel at an extended period, but the release rate of bFGF-NPs/hydrogel was much lower. In vivo experiments suggested that immunogenicity of bFGF improved significantly after being incorporated into the NPs/hydrogel composite, and strong humoral immunity was maintained for longer than 12 weeks. Furthermore, an in vivo protective anti-tumor immunity assay indicated that immunization with bFGF-NPs/hydrogel could induce significant suppression of the growth and metastases of tumors. Thus, the NPs/hydrogel composite may have great potential application as a novel vaccine delivery system.