D-methionine eradicates Porphyromonas gingivalis biofilms by suppressing the cyclic di-GMP level / 口腔疾病防治

Objective@#To investigate the mechanisms by which D-methionine (D-Met) eradicates Porphyromonas gingivalis biofilms by suppressing cyclic dimeric GMP (c-di-GMP) levels.@*Methods @#Cell viability, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were measured to determine the effective concentrations of D-Met, which were subsequently used in the following experiments. During the P. gingivalis biofilm formation inhibition experiment and the mature biofilm disassembly experiment, biofilm biomass, exopolysaccharide (EPS), biofilm morphology, integrity of the cell membrane, and the level of c-di-GMP were determined. @*Results @# D-Met < 40 mmol/L was biocompatible. During the biofilm formation inhibition and mature biofilm disassembly experiments, D-Met ≥ 20 mmol/L decreased the biofilm biomass and the production of EPS. SEM analysis showed that the extracellular matrix and bacterial density were drastically reduced by D-Met ≥ 20 mmol/L. TEM detection showed that 35 mmol/L D-Met ruptured the cell membrane during biofilm formation and increased the permeability of the cell membrane in the disassembly phase of mature biofilms. C-di-GMP levels decreased with increasing concentrations of D-Met in a concentration-dependent manner.@* Conclusion @# D-Met ≥ 20 mmol/L could eradicate P. gingivalis biofilms by suppressing c-di-GMP levels.

Effects of chronic stress caused by occlusal disorder on the body / 口腔疾病防治

@#Occlusal disorder is an abnormal condition in which the static and dynamic relations between the upper and lower teeth are not well aligned . The most common occlusal disorder in clinical practice is the inability to reach the intercuspal position due to early contact of individual points or occlusal interference due to occlusal high points, which can lead to periodontal tissue damage, decreased masticatory function, temporomandibular joint and muscle discomfort; these results can occur through the overactivation of the locus coeruleus-sympathetic-adrenal medullary system and hypothalamic-pituitary-adrenal axis induce elevated serum corticosteroid levels, which leads to chronic stress in the body. This article reviews the effects of chronic stress caused by occlusal disorder on bone tissue, stomatognathic system, emotional health and cognitive function. It has been found that occlusal disorders not only result in the loss of bone in the oral cavity, the reduction of bone mass in the whole body and damage to the local function of the stomatognathic system but also negatively affect the body’s anxiety, sleep, cognitive function and spatial memory ability as a result of the neuroendocrine changes . In recent years, concern about occlusal disorders has been on the rise. Early detection and timely adjustment of uncoordinated occlusion has become an issue that cannot be ignored in the clinic.