To investigate the effect of different decontamination methods, including photodynamic therapy, sandblasting and titanium curette, on titanium surface morphology and bacterial adhesion for the treatment of peri-implant disease.

Porphyromonas gingivalis (Pg) and Fusobacterium nucleatum (Fn) were inoculated on the surface of polished titanium specimens, and titanium specimen surfaces were treated with different decontamination methods after incubation. The titanium specimens were divided into a no-treatment control group, photodynamic group, sandblasting group and titanium curette group according to different decontamination methods. The changes in titanium surface roughness were observed by atomic force microscopy (AFM), and the remaining bacteria on the titanium surface were observed by scanning electron microscopy (SEM) and live/dead bacteria staining tests. After reinoculation of Pg and Fn, bacterial readhesion was observed on the surface of decontaminated titanium specimens.

The AFM results showed that the surface roughness of the titanium curette group was significantly higher than that of the no-treatment control group, photodynamic group and sandblasting group (P ＜ 0.05), and there was no statistically significant difference between the no-treatment control group, photodynamic group and sandblasting group (P ＞ 0.05). The results of contact angle measurement showed that the surface contact angle of each treatment group was smaller than that of the no-treatment control group (P ＜ 0.05). The SEM results obtained after the titanium specimen surface was decontaminated showed that the number of bacteria on the no-treatment control group surface was higher and the bacteria were relatively concentrated. The bacteria on the surface of the photodynamic group, sandblasting group and titanium curette group were scattered and distributed in small numbers, and most bacteria on the surface of the photodynamic group were ruptured. The results of the live/dead bacteria staining experiment showed that the percentage of dead bacteria on the surface of the photodynamic group was significantly higher than that of the no-treatment control group, sandblasting group and titanium curette group (P ＜ 0.05). The remaining bacteria on the surface of the sandblasting group and titanium curette groups were mainly live bacteria. The remaining bacterial adhesion on the surface was significantly reduced for the sandblasting group compared to the no-treatment control group and the photodynamic and titanium curette groups (P ＜ 0.05). SEM and live/dead bacteria staining results of bacterial readhesion on the surface of titanium specimens showed that there was an aggregation of Pg on the surface of the titanium curette group, and its surface bacterial adhesion was significantly higher than that of the no-treatment control group, photodynamic group and sandblasting group.

In mechanical decontamination, sandblasting machines are a better option than photodynamic therapy and titanium curettes; however, sandblasting does not remove all bacterial contamination. For sterilization, photodynamic therapy is more effective than sandblasting and titanium curettes. A combination of sandblasting and photodynamic therapy methods for the treatment of peri-implant disease may be considered in clinical practice.

To investigate the changes of mitochondrial homeostasis of human gingival fibroblasts (HGFs)in periodontitis, and to provide a basis for exploring the mechanism of periodontitis.

This study has been reviewed and approved by the Ethics Committee. Gingival tissue was collected from patients who underwent periodontal surgery at the Department of Periodontology, School of Stomatology, the Fourth Military Medical University, from June 1, 2023 to December 31, 2023. All of the subjects signed informed consent forms prior to surgery. Gingival connective tissues were collected from patients with chronic periodontitis (CP group) and healthy individuals (control group) undergoing flap surgery and crown lengthening surgery, respectively. There were 6 cases in each group. The primary HGFs obtained from healthy periodontal subjects were cultured and divided into the control group (cultured in complete medium for 24 h)and the Pg.LPS group (cultured in medium with 5μg/m L Pg.LPS for 24 h). The number, morphology, and structure of mitochondria in gingival connective tissue and HGFs were observed by transmission electron microscopy. The number, circumference, and surface area of mitochondria were quantitatively analyzed. MitoSOX^TMRed, TMRM, and an ATP kit were used to determine the production levels of mitochondrial reactive oxygen species, mitochondrial membrane potential, and ATP in each group of HGFs.

Transmission electron microscopy showed that the morphology and structure of mitochondria were abnormal in the gingival connective tissues of the periodontitis group and HGFs, which were stimulated by Pg.LPS. The mitochondrial ridges were broken or were not visible in these groups. The number of mitochondria decreased significantly, and the surface area and circumference of the mitochondria increased significantly (P<0.05). In addition, after stimulation by Pg.LPS, the reactive oxygen species level in HGFs was significantly higher than that in the control group (P<0.05). The mitochondrial membrane potential and the level of ATP production was significantly lower than that of the control group (P<0.05).

The number, morphological structure, and function of mitochondria in HGFs changed significantly in periodontitis. The mitochondrial homeostasis is closely related to the occurrence and development of periodontitis.