Interorifice Distance Research Articles

Detection of Permanent Three-rooted Mandibular First Molars by Cone-Beam Computed Tomography Imaging in Taiwanese Individuals

This study determined the prevalence of permanent three-rooted mandibular first molars and their morphology among a Taiwanese population by using cone-beam computed tomography (CBCT). Images from 744 patients were screened to obtain 123 samples for this study. All permanent mandibular first molars were evaluated in axial sections from the pulpal floor to the apices of the roots to determine the number of roots. The interorifice distances from the distolingual (DL) canal to the mesiobuccal (MB) and distobuccal (DB) canals were also estimated. The prevalence of permanent three-rooted mandibular first molars was 33.33%, with a bilateral incidence of a symmetrical distribution of 53.65%. There was a significantly greater incidence of three-rooted teeth on the right side of the mandible than on the left, but gender did not show a significant relationship with this variant prevalence.The mean interorifice distances from the DL canal to the DB, MB, and ML canals of the permanent three-rooted mandibular molars were 2.7, 4.4, and 3.5 mm, respectively. The high prevalence of the DL root in permanent mandibular first molars among the Taiwanese (Chinese) population and estimations of the interorifice distance of such teeth might be useful for successful endodontic treatments.

Bubble formation at closely spaced orifices in aqueous solutions

A filter cloth with 182 holes per 10 −4 m 2 has been used to generate air bubbles both in pure water and in aqueous solutions of electrolytes and non-electrolytes at various air flow rates. Potassium bromide and ammonium perchlorate were the electrolytes used, while the non-electrolytes were isopropanol, urea and glycerol. Bubble diameters and their size distribution were measured from photographs. The role of solutes in affecting bubble sizes and their distribution compared to that of pure water is discussed in the light of a hypothesis. This hypothesis assumes that if the final bubble diameter is less than the inter-orifice distance, then bubbles do not coalesce; on the other hand, if it is greater, then coalescence occurs when t f ⩾ t i+ t s, but does not occur when t< t i+ t s. Further, the bimodal size distribution is explained by the idea of a phase lag.

A study on the low Reynolds number flow in a valved vessel

The understanding of the fluid flow in valved vessels is of importance pertaining to its application to the problem of fluid transport in valved vessels of the living body, such as veins and lymphatic ducts. In order to have a quantitative understanding of fluid flow through valved vessels, the Newtonian fluid flow through a rigid circular cylindrical tube involving a series of uniformly spaced plate orifices of axisymmetric geometry is studied at low Reynolds number. The solution of the above problem is posed as a series solution of the Stokes equation and the equation of continuity, satisfying the appropriate boundary conditions. The velocity distributions and the average rate of the mean pressure change along the tube axis are computed for a number of different combinations of the orifice-tube radius ratio and the ratio of the inter-orifice distance to the tube radius. The results of the analysis are discussed for possible application to certain physiological systems.