Date Published: January 26, 2017
Publisher: Public Library of Science
Author(s): Sigrun Eick, Ivan Meier, Florian Spoerlé, Philip Bender, Akira Aoki, Yuichi Izumi, Giovanni E. Salvi, Anton Sculean, Binnaz Leblebicioglu.
Bacterial biofilms play a major role in the etiology of periodontal and peri-implant diseases. The aim of the study was to evaluate the removal of bacterial biofilms and attachment of epithelial cells (EC), gingival fibroblasts (GF) and osteoblast-like cells (OC) to dentin and titanium surfaces after Er:YAG laser (Er:YAG) in comparison with other treatment methods.
Multi-species bacterial biofilms were grown on standardized dentin and titanium specimens with a sand-blasted and acid etched (SLA) surface for 3.5 d. Thereafter, the specimens were placed into artificially-created pockets. The following methods for biofilm removal were used: 1) Gracey (dentin) or titanium curettes (CUR), 2) Er:YAG, 3) photodynamic therapy (PDT) and 4) CUR with adjunctive PDT (CUR/PDT). Colony forming units (CFUs) of the remaining biofilms and attachment of EC, GF and OC were determined. Statistical analysis was performed by means of ANOVA with post-hoc LSD.
All treatment methods decreased statistically significantly (p<0.001) total CFUs in biofilms compared with untreated dentin and titanium surfaces respectively. On dentin, Er:YAG was equally efficient as CUR and PDT but inferior to CUR/PDT (p = 0.005). On titanium, surfaces, the use of Er:YAG resulted in statistically significantly superior biofilm removal compared to the 3 other treatments (each p<0.001). Counts of attached EC, GF and OC were the lowest on untreated contaminated dentin and titanium surfaces each. After CUR/PDT higher EC counts were found on dentin (p = 0.006). On titanium, all decontamination methods statistically significantly increased (p<0.001) the counts of attached EC without differences between groups. Statistically significantly higher counts of GF (p = 0.024) and OC (p<0.001) were observed after Er:YAG decontamination compared with untreated surfaces. Ablation of subgingival biofilms and in particular decontamination of titanium implant surfaces with an Er:YAG laser seem to be a promising approach and warrants further investigations.
Lasers have been introduced in dentistry in the 60ies of last century. In one of the first reports a ruby laser with an energy density of about 9’000 J / cm2 was applied for destruction of carious lesions in in-vitro experiments . Meanwhile, lasers were introduced in nearly all fields of dentistry including endodontics, periodontology, implantology, oral surgery, orthodontics and cariology . The term “LASER” stands for “Light Amplification by Stimulated Emission of Radiation”. The principle is that electrons being normally in a low energy state are transferred to a high energy state; when moving back to the low energy state the absorbed energy is released. Lasers used in dentistry are differentiated between low-intensity (e.g. diode lasers) and high-intensity lasers (e.g. Erbium-Doped: Yttrium, Aluminum, Garnet (Er:YAG) laser). In periodontal therapy low-intensity lasers are discussed to improve wound healing and combined with photosensitizer (photodynamic therapy) they can act exert antimicrobial activity .
The present in-vitro study has evaluated the application of Er:YAG laser in comparison with hand instruments and photodynamic therapy in ablation of periodontal and peri-implant biofilms.
Within their limits, the present data indicate that: a) on dentin surfaces, Er:YAG laser appears to be equally effective as hand instrumentation for removing bacterial biofilms, b) the combination of CUR and PDT appears to be a suitable method to additionally decontaminate dentin surfaces, and c) on titanium surfaces, the use of Er:YAG laser yielded clear advantages compared to the other debridement modalities.