AIM To investigate the effect of ageing on control mechanisms of pulpal microcirculation using wavelet analysis and to calculate linear and nonlinear parameters of blood flow oscillations, in a healthy general population. METHODOLOGY Pulpal blood flow (PBF) oscillations were recorded on right maxillary central incisors using laser Doppler Flowmeter (PeriFlux PF 5001, Perimed, Jarfalla, Sweden) on a group of 10 young participants (20-25 years) and a group of 10 older adults (60-70 years). In total, 20 recordings were obtained for at least 20 min (one recording on one tooth per subject). Using wavelet spectral analysis, the amplitude and power were calculated as a linear and Hurst exponent as a nonlinear parameter of PBF oscillations. Differences between the two groups were assessed with the independent Student t-test. RESULTS Mean PBF levels were significantly lower (P = 0.024) in older adults than in young participants. Relative amplitudes and powers corresponding to the myogenic (P = 0.046, P < 0.001, respectively) and neurogenic activity (P = 0.04, P = 0.01, respectively) were significantly higher, whereas values corresponding to the endothelial function (P = 0.04, P = 0.01, respectively) were significantly lower in older adults than in young participants. Hurst exponents of the total spectrum, myogenic and endothelial component (P < 0.001, P = 0.02, P < 0.001, respectively) of PBF oscillations were significantly lower in older adults in comparison to young participants. CONCLUSIONS At the level of pulpal microcirculation, ageing was associated with altered blood flow levels, the contribution of different control mechanisms to blood flow oscillations as well as the interaction of vascular smooth muscle and endothelium. Described changes of pulpal haemodynamics contribute to a better understanding of physiological behaviour and decreased adaptability of aged dental pulp to pathological stimuli.

中文翻译：

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老化过程中牙髓血流振荡的线性和非线性分析。

目的通过小波分析研究衰老对牙髓微循环控制机制的影响，并计算健康人群中血液流动振荡的线性和非线性参数。方法：使用激光多普勒流量计（PeriFlux PF 5001，Perimed，Jarfalla，瑞典）在一组10名年轻参与者（20-25岁）和一组10名成年人中记录右上颌中切牙的肺血流（PBF）振荡（60-70年）。总共获得了至少20分钟的20个记录（每个受试者在一颗牙齿上记录一个）。使用小波频谱分析，将振幅和功率计算为线性，将Hurst指数计算为PBF振荡的非线性参数。两组之间的差异通过独立的学生t检验进行评估。结果老年人的平均PBF水平显着低于年轻人（P = 0.024）。对应于肌源性（P = 0.046，P <0.001）和神经源性活动（P = 0.04，P = 0.01）的相对幅度和功效显着更高，而对应于内皮功能的值（P = 0.04，P =分别为0.01）在老年人中明显低于年轻参与者。与年轻人相比，老年人的PBF振荡的总谱，肌原性和内皮成分的赫斯特指数（分别为P <0.001，P = 0.02，P <0.001）显着较低。结论在牙髓微循环水平，衰老与血流水平改变有关，不同控制机制对血流振荡以及血管平滑肌和内皮相互作用的贡献。牙髓血流动力学的变化有助于更好地理解生理行为，并降低了老年牙髓对病理刺激的适应性。