The Effects of Ultraviolet Light-Emitting Diodes with Different Wavelengths on Periodontopathic Bacteria In Vitro

The effect of antimicrobial photodynamic therapy using yellow-green LED and rose bengal on Porphyromonas gingivalis

INTRODUCTION

This study aimed to investigate the effects of a new antimicrobial photodynamic therapy (aPDT) system using yellow-green light-emitting diode (YGL) and rose bengal (RB) on Porphyromonas gingivalis (Pg) in vitro.

MATERIALS AND METHODS

Pg suspension mixed with RB was irradiated with YGL (565 nm) or blue light-emitting diode (BL, 470 nm) at 428 mW/cm² in comparison with chlorhexidine (CHG) treatment. The cells were cultured anaerobically on agar plates, and the number of colony-forming units (CFU) was determined. The treated suspension was anaerobically incubated, and the cell density (OD_600nm) was monitored for 24 h. Also, the viability of treated human gingival fibroblast (HGF-1) was measured using WST-8 assay. Pg morphology was observed with a scanning electron microscope. The RNA integrity number of aPDT-treated Pg was determined and gene expressions were evaluated by quantitative real-time polymerase chain reaction.

RESULTS

RB + YGL (aPDT) demonstrated a significantly higher reduction of CFU, compared to RB + BL (aPDT) and CHG, furthermore the OD value rapidly decreased. Morphological changes of Pg with RB + YGL were more severe than with CHG. Although RB + YGL reduced HGF-1 viability, aPDT's impact was significantly lower than CHG's. With RB + YGL treatment, RIN values decreased; furthermore, gene expressions associated with DNA replication and cell division were remarkably decreased after 12 h.

CONCLUSION

The results of this study demonstrated that a novel aPDT system using RB + YGL may have potential as a new technical modality for bacterial elimination in periodontal therapy.

Effect of Laser Radiation on Infected Sites for the Immediate Placement of Dental Implants

Objective: The study aims to evaluate the feasibility of erbium-chromium: yttrium-scandium-gallium-garnet (ErCr:YSGG 2780 nm) laser irradiation on infected and/or inflamed post-extraction sites for the immediate placement, and when possible, immediate loading, of endosseous implants. Background: Post-extraction site infection is a serious complication. Surgical and nonsurgical options are available to treat such event, together with various decontamination methods. However, there is still no consensus on which treatment is the most effective. Materials and methods: Sixty-six patients were included in the study for a total of 94 post-extraction implants, inserted in the maxilla and mandible. All patients were eligible for implant therapy, having at least one compromised tooth requiring extraction, along with sign of inflammation and/or infection. Surgery and socket decontamination were performed using an ErCr:YSGG laser. To improve bone healing, Bio-Oss^® and resorbable membrane were used in 57 patients. Eleven implants were immediately loaded, whereas 83 were loaded within 3-6 months, depending on the extraction site. Intraoral radiographs were taken at 1, 3, 6, 9, and 12 months from the implant placement to assess the alveolar bone level and treatment's outcome. Albrektsson criteria were chosen to evaluate the treatment success rate. Results: Follow-up went from 6 months to 4 years. Success rate was 94.6% (89/94): three implants failed to integrate due to poor patient compliance, being expelled during the second week, whereas two implants presented factory defects (abutment). No sockets presented signs of residual infection during follow-up. Conclusions: The combination of mechanical, chemical, and laser treatment was proven to be highly effective for the disinfection of post-extraction sites. The ErCr:YSGG laser is a useful tool, not only for his practicality as a surgical device but also as a disinfection tool, granting optimal results after implant surgery.