Resumen de Antimicrobial Action of Minocycline Microspheres Versus 810-nm Diode Laser on Human Dental Plaque Microcosm Biofilms
Background: The purpose of this study is to investigate the antimicrobial effects of minocycline hydrochloride microspheres versus infrared light at 810 nm from a diode laser on multispecies oral biofilms in vitro. These biofilms were grown from dental plaque inoculum (oral microcosms) and were obtained from six systemically healthy individuals with generalized chronic periodontitis.
Methods: Multispecies biofilms were derived using supra- and subgingival plaque samples from mesio-buccal aspects of premolars and molars exhibiting probing depths in the 4- to 5-mm range and 1- to 2-mm attachment loss. Biofilms were developed anaerobically on blood agar surfaces in 96-well plates using a growth medium of prereduced, anaerobically sterilized brain�heart infusion with 2% horse serum. Minocycline HCl 1 mg microspheres were applied on biofilms on days 2 and 5 of their development. Biofilms were also exposed on days 2 and 5 of their growth to 810-nm light for 30 seconds using a power of 0.8 W in a continuous-wave mode. The susceptibility of microorganisms to minocycline or infrared light was evaluated by a colony-forming assay and DNA probe analysis at different time points.
Results: At all time points of survival assessment, minocycline was more effective (>2 log10 colony-forming unit reduction) than light treatment (P <0.002). Microbial analysis did not reveal susceptibility of certain dental plaque pathogens to light, and it was not possible after treatment with minocycline due to lack of bacterial growth.
Conclusion: The cumulative action of minocycline microspheres on multispecies oral biofilms in vitro led to enhanced killing of microorganisms, whereas a single exposure of light at 810 nm exhibited minimal and non-selective antimicrobial effects.
Biofilm-associated inflammatory diseases of the attachment apparatus around teeth in the oral cavity, collectively known as periodontal diseases, represent a major part of the global burden of oral disease. Gingivitis occurs in 90% of adults,1 whereas periodontitis affects >47% of the American population aged >30 years, and it is severe (>4 mm attachment loss [AL]) in 13% of adults.2 Periodontitis is also suggested as a risk factor for coronary heart disease,3 atherosclerosis,4 preterm births,5 and chronic kidney disease.6 The primary microbial factor contributing to disease is a shift from beneficial to pathogenic bacteria within dental plaque, and the primary immunologic factor is the destructive host inflammatory response.7 Mechanical removal of periodontal biofilms (brushing, scaling and root planing [SRP]) is the method of treatment. However, residual microorganisms recolonize the subgingival environment immediately after SRP and form new biofilms.8 The local use of antibacterial agents in sustained-release vehicles as an adjunct to SRP has statistically significant effects on probing depth (PD) reduction and a decreased percentage of sites with bleeding on probing.9 On the other hand, the use of infrared light (805 to 810 nm) after SRP was reported to have clinical benefits10,11 and exhibit antimicrobial action.12 However, two recent systematic reviews were not able to offer consistent evidence supportive of the efficacy of laser treatment as an adjunct to non-surgical periodontal treatment in individuals with chronic periodontitis (CP).13,14 Recently, the American Academy of Periodontology stated that there is lack of consistent evidence to support the use of laser treatment for subgingival debridement either alone or as an adjunct to non-surgical periodontal therapy.15 To the authors� knowledge, there exist no data comparing, side-by-side, the antimicrobial effects of local sustained-release agents and infrared light on dental plaque-derived biofilms in vitro. In the present study, the authors investigate the antimicrobial effects of minocycline microspheres§ � a subgingival sustained-release product containing minocycline hydrochloride into poly(glycolide-co-d,l-lactide) � and infrared light with a wavelength of 810 ± 20 nm from a diode laser on multispecies oral biofilms grown in vitro from human dental plaque inoculum (oral microcosms).
