Satisfactory host bone quality and quantity promote greater primary stability and better osseointegration, leading to a high success rate in the use of dental implants. However, the increase in life expectancy as a result of medical advancements has led to an aging population, suggesting that osteoporosis may become a problem in clinical dental implant surgery. Notably, relative to the general population, bone insufficiency is more common in women with post-menopausal osteoporosis. The objective of this study was to compare the thickness of the crestal cortical bone at prospective dental implant sites between menopausal and non-menopausal women. Prospective dental implant sites in the jawbone were evaluated in two groups of women: a younger group (<50 years old), with 149 sites in 48 women, and an older group (>50 years old) with 191 sites, in 37 women. The thickness of the crestal cortical bone at the dental implant site was measured based on each patient’s dental cone-beam computed tomography images. For both groups, one-way analysis of variance and Tukey’s post-test were used to assess the correlation between cortical bone thickness and the presence of implants in the four jawbone regions. Student’s t-test was further used to compare differences between the older and younger groups. From the retrospective study results, for both groups, thickness of the crestal cortical bone was the highest in the posterior mandible, followed by anterior mandible, anterior maxilla, and posterior maxilla. Compared with the younger group, the older group had a lower mean thickness of the crestal cortical bone. Among the four regions, however, only in the posterior maxilla was the crestal cortical bone significantly thinner in the older group than in the younger group.

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As regional diaphragmatic microvascular blood flow varies widely, the aim in this study was to estimate the number of repeated measurements, obtained by Laser-Doppler flowmetry (LDF), required to achieve a standard level of precision. In 40 urethane-anesthetized Sprague-Dawley rats, computer-aided LDF scanning coupled with a microscope generated diaphragmatic blood flow (Qdi) ranging between 94 and 944 mV with the frequency histogram displaying non-Gaussian distributions. A sampling technique was used to assess the number of measuring sites required for valid estimates of the regional diaphragmatic microvascular flow. From a total of 1,000 Qdi values, random samples of sizes between 5 and 100 were repeatedly drawn to estimate the variability of median flow. Our data shows that the 95th percentile decreased gradually, from a +30% error at n = 5 down to +20% at n = 15-20, remained between +20 and +15% up to n = 35, and reached + 10% at n = 50. Moreover, by expressing the precision level of measurements as the length of a 95% confidence interval (β), a linear relationship between β values obtained either by the sampling method or repeated measures analysis of variance can be shown (r = 0.902, p < 0.001); β values by either method were within ± 20% error of the mean values at sample sizes above n = 15. It is therefore recommended that for microscope-guided LDF scanning in the assessment of the distribution of diaphragmatic microvascular blood flow, at least 15 repeated measurements should be done to reach an acceptable standard level of precision. However, facing with clinical situations where ‘blind’ LDF scanning inevitably includes measurements over large vessels, the minimal sample sizes required to represent tissue perfusion demand further exploration.