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Giannelli M.,Odontostomatologic Laser Therapy Center | Pini A.,University of Florence | Formigli L.,University of Florence | Bani D.,University of Florence
Photomedicine and Laser Surgery | Year: 2011

Objective and background: The present in vitro study was designed to evaluate and compare the efficacy of: 1) different dental laser devices used in photoablative (PA) mode, namely commercial CO 2, Er:YAG, and Nd:YAG lasers and a prototype diode laser (wavelength = 810 nm); 2) prototype low-energy laser diode or light-emitting diode (LED) (wavelength = 630 nm), used in photodynamic (PD) mode together with the photoactivated agent methylene blue; and 3) chlorhexidine, used as reference drug, to reduce the activation of macrophages by lipopolysaccharide (LPS), a major pro-inflammatory gram-negative bacterial endotoxin, adherent to titanium surface. Methods: RAW 264-7 macrophages were cultured on titanium discs, cut from commercial dental implants and precoated with Porphyromonas gingivalis LPS. Before cell seeding, the discs were treated or not with the noted lasers and LED in PA and PD modes, or with chlorhexidine. The release of nitric oxide (NO), assumed to be a marker of macrophage inflammatory activation, in the conditioned medium was related to cell viability, evaluated by the MTS assay and ultrastructural analysis. Results: PA laser irradiation of the LPS-coated discs with Er:YAG, Nd:YAG, CO 2, and diode (810 nm) significantly reduced NO production, with a maximal inhibition achieved by Nd:YAG and diode (810 nm). Similar effects were also obtained by PD treatment with diode laser and LED (630 nm) and methylene blue. Notably, both treatments were superior to chlorhexidine in terms of efficiency/toxicity ratio. Conclusions: These findings suggest that laser and LED irradiation are capable of effectively reducing the inflammatory response to LPS adherent to titanium surface, a notion that may have clinical relevance. Copyright 2011, Mary Ann Liebert, Inc. Source

Giannelli M.,Odontostomatologic Laser Therapy Center | Chellini F.,University of Florence | Sassoli C.,University of Florence | Francini F.,University of Florence | And 6 more authors.
Journal of Cellular Physiology | Year: 2013

Mesenchymal stromal cells (MSCs) are a promising cell candidate in tissue engineering and regenerative medicine. Their proliferative potential can be increased by low-level laser irradiation (LLLI), but the mechanisms involved remain to be clarified. With the aim of expanding the therapeutic application of LLLI to MSC therapy, in the present study we investigated the effects of 635nm diode laser on mouse MSC proliferation and investigated the underlying cellular and molecular mechanisms, focusing the attention on the effects of laser irradiation on Notch-1 signal activation and membrane ion channel modulation. It was found that MSC proliferation was significantly enhanced after laser irradiation, as judged by time lapse videomicroscopy and EdU incorporation. This phenomenon was associated with the up-regulation and activation of Notch-1 pathway, and with increased membrane conductance through voltage-gated K+, BK and Kir, channels and T- and L-type Ca2+ channels. We also showed that MSC proliferation was mainly dependent on Kir channel activity, on the basis that the cell growth and Notch-1 up-regulation were severely decreased by the pre-treatment with the channel inhibitor Ba2+ (0.5mM). Interestingly, the channel inhibition was also able to attenuate the stimulatory effects of diode laser on MSCs, thus providing novel evidence to expand our knowledge on the mechanisms of biostimulation after LLLI. In conclusions, our findings suggest that diode laser may be a valid approach for the preconditioning of MSCs in vitro prior cell transplantation. © 2012 Wiley Periodicals, Inc. Source

Giannelli M.,Odontostomatologic Laser Therapy Center | Formigli L.,University of Florence | Lasagni M.,General Project Ltd | Bani D.,University of Florence
Photomedicine and Laser Surgery | Year: 2013

Objective: The purpose of this study was to optimize gingival laser photoablation by thermographic and autofluorescent feedbacks. Background data: Photoablative laser treatment is commonly used for gingival de-epithelization in patients with chronic periodontitis or hyperpigmentation. The reduction of collateral thermal damage of periodontal tissues is crucial for optimal treatment outcome. Methods: Nineteen patients with chronic periodontitis, seven of whom showing gingival hyperpigmentation, were subjected to de-epithelization with an 810 nm diode laser used in continuous (1 W, 66.67 J/cm2) or pulsed wave mode (69 μJ, 18 μs, 8000 Hz, corresponding to peak/mean power of 3.8 W/0.6 W, 40 J/cm2), depending upon individual gingival features. Photoablation was controlled in real time with a 405 nm violet light probe, which stimulated a yellow autofluorescence of the laser-coagulated tissue. The temperature at the target tissue was controlled with an infrared thermographic probe. When appropriate, small biopsies were taken to evaluate epithelial ablation and thermal effects. Results: The energy density transferred to the treated tissue surface was computed based on the irradiation modality of the target tissues. Laser photoablation performed under thermographic control yielded complete removal of the gingival epithelium with minimal injury to the underlying lamina propria. Irradiation-evoked autofluorescence, conceivably the result of epithelial keratins, allowed very sharp recognition of the borders between laser-ablated and intact epithelium, thus preventing repeated irradiation. Conclusions: This study further supports the favorable characteristics of photoablative diode laser for gingival de-epithelization. Concurrent thermographic and fluorescent analysis can provide substantial help to the setup of a safe and well-tolerated protocol. © Copyright 2013, Mary Ann Liebert, Inc. 2013. Source

Giannelli M.,Odontostomatologic Laser Therapy Center | Formigli L.,University of Florence | Bani D.,University of Florence
Journal of Periodontology | Year: 2014

The use of lasers in periodontology is a matter of debate, mainly because of the lack of consensual therapeutic protocols. In this randomized, split-mouth trial, the clinical efficacy of two different photoablative dental lasers, erbium:yttrium-aluminum-garnet (Er:YAG) and diode, for the treatment of gingival hyperpigmentation is compared. Methods: Twenty-one patients requiring treatment for mild-to-severe gingival hyperpigmentation were enrolled. Maxillary or mandibular left or right quadrants were randomly subjected to photoablative deepithelialization with either Er:YAG or diode laser. Masked clinical assessments of each laser quadrant were made at admission and days 7, 30, and 180 postoperatively by an independent observer. Histologic examination was performed before and soon after treatment and 6 months after irradiation. Patients also compiled a subjective evaluation questionnaire. Results: Both diode and Er:YAG lasers gave excellent results in gingival hyperpigmentation. However, Er:YAG laser induced deeper gingival tissue injury than diode laser, as judged by bleeding at surgery, delayed healing, and histopathologic analysis. The use of diode laser showed additional advantages compared to Er:YAG in terms of less postoperative discomfort and pain. Conclusions: This study highlights the efficacy of diode laser for photoablative deepithelialization of hyperpigmented gingiva. It is suggested that this laser can represent an effective and safe therapeutic option for gingival photoablation. J Periodontol 2014;85:554-561. © 2013 American Academy of Periodontology. Source

Giannelli M.,Odontostomatologic Laser Therapy Center | Lasagni M.,General Project Ltd
Lasers in Medical Science | Year: 2015

Diode lasers are widely used in dental laser treatment, but little is known about their thermal effects on different titanium implant surfaces. This is a key issue because already a 10 °C increase over the normal body temperature can induce bone injury and compromise osseo-integration. The present study aimed at evaluating the temperature changes and surface alterations experienced by different titanium surfaces upon irradiation with a λ = 808 nm diode laser with different settings and modalities. Titanium discs with surfaces mimicking different dental implant surfaces including TiUnite and anodized, machined surfaces were laser-irradiated in contact and non-contact mode, and with and without airflow cooling. Settings were 0.5–2.0 W for the continuous wave mode and 10–45 μJ, 20 kHz, 5–20 μs for the pulsed wave mode. The results show that the surface characteristics have a marked influence on temperature changes in response to irradiation. The TiUnite surface, corresponding to the osseous interface of dental implants, was the most susceptible to thermal rise, while the machined surfaces, corresponding to the implant collar, were less affected. In non-contact mode and upon continuous wave emission, the temperature rose above the 50 °C tissue damage threshold. Scanning electron microscopy investigation of surface alterations revealed that laser treatment in contact mode resulted in surface scratches even when no irradiation was performed. These findings indicate that the effects of diode laser irradiation on implant surfaces depend on physical features of the titanium coating and that in order to avoid thermal or physical damage to implant surface the irradiation treatment has to be carefully selected. © 2015, Springer-Verlag London. Source

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