RESUMEN
Reconstruction of lost tooth structures and the periodontium with the help of tissue engineering has found a special place in dentistry in recent years with reports of great therapeutic success. Stem cells from the periodontal ligament have the potential for high differentiation into the bone and periodontal ligament cells and are therefore a suit candidate for regenerative therapies of the periodontium and other tissues. In this regard, the use of photobiomodulation on these cells by light irradiation can be effective in increasing the efficiency of these regenerative methods. The effect of red and near-infrared lasers was investigated in pulsed and continuous modes on the cell viability, ROS production and the cell cycle of Periodontal Ligament Stem cells (PDLSCs) using MTT assay and flowcytometry techniques. The result shows that both red and near-infra-red (NIR) irradiations at 3 J/cm2 maintain cell viability. ROS generation assay indicated that in PDL stem cells irradiated with NIR laser (940 nm), ROS production was greater than in the red (660 nm) irradiated groups. Cell cycle analysis revealed that NIR irradiation can enhance the proportion of S-phase cells and declinedecline the proportion of G1-phase cells compared to the red laser irradiation groups. Moreover, this enhancement was greater in the pulsed group compared to the continuous mode group. Overall, the current study results showed that photobiomodulation can support the cell viability of PDLSCs and could affect the ROS production and cell cycle. This effect was more with 940 nm (NIR) irradiation pulsed mode compared to 660 nm (red).Communicated by Ramaswamy H. Sarma.
Asunto(s)
Ligamento Periodontal , Células Madre , Ligamento Periodontal/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Células Cultivadas , Diferenciación Celular , Células Madre/metabolismo , Ciclo Celular , Proliferación CelularRESUMEN
Purpose: To aid in the selection of a suitable combination of irradiation mode and jaw width in helical tomotherapy (HT) for the treatment of nasopharyngeal carcinoma (NPC). Materials and Methods: Twenty patients with NPC who underwent radiotherapy were retrospectively selected. Four plans using a jaw width of 2.5 or 5-cm in dynamic jaw (DJ) or fix jaw (FJ) modes for irradiation were designed (2.5DJ, 2.5FJ, 5.0DJ, and 5.0FJ). The dose parameters of planning target volume (PTV) and organs at risk (OARs) of the plans were compared and analyzed, as well as the beam on time (BOT) and monitor unit (MU). The plans in each group were ranked by scoring the doses received by the OARs and the superity was assessed in combination with the planned BOT and MU. Results: The prescribed dose coverage of PTV met the clinical requirements for all plans in the four groups. The groups using a 2.5-cm jaw width or a DJ mode provided better protection to most OARs, particularly for those at the longitudinal edges of the PTV (P < 0.05). The 2.5DJ group had the best ranking for OAR-dose, followed by the 2.5FJ and 5.0DJ groups with a same score. The BOT and MU of the groups using a 5.0-cm jaw width reduced nearly 45% comparing to those of the 2.5-cm jaw groups. Conclusion: 2.5DJ has the best dose distribution, while 5.0DJ has satisfactory dose distribution and less BOT and MU that related to the leakage dose. Both 2.5DJ or 5DJ were recommended for HT treatment plan for NPC based on the center workload.
RESUMEN
High-power light-curing units have emerged that reduce the time of procedures in dental clinical work. However, patients sometimes complain of pain during the polymerization of composite resin. In this experiment, we investigated how differences in light-curing mode affect the temperature rise during composite resin polymerization in vitro. Light-curing mode conditions were divided into four groups: 3 s in plasma mode (Plm3) and 5, 10, and 20 s in standard mode. The temperature curve under Plm3 exhibited a rapid increase during the first 3 s of light curing before reaching a maximum of around 55°C. In contrast, the temperature rose rapidly but less sharply for irradiation in each standard mode compared with Plm3. These results suggest that irradiation using a high-power mode increases the temperature at an excessively high rate, and this may raise concern about side effects on the pulp.