Assessment of vinyl polysiloxane as an innovative injection material for the anatomical study of vasculature.

There are numerous injection materials for the study of vasculature in anatomical specimens, each having its own advantages and disadvantages. Latex and resins are the most widely used injection materials but need several days to set. The development of new materials taking shorter time to polymerize might be very useful to improve anatomic specimen study conditions. The aim of the present study was to evaluate vinyl polysiloxane (VPS), a silicon material widely used for dental impressions with the advantage to set very rapidly, as an injection material. We assessed the preparation, use, diffusion and setting time of the product in different anatomical regions (central nervous system, external carotid/jugular, lower limb) to observe its behavior in variably sized vessels. Our results suggest that VPS might be of interest for the study of vessels in anatomical specimens. The main strengths of the product are represented by (1) simplicity of use, as it is a ready-to-use material, (2) very rapid polymerization, (3) availability in a range of viscosities making easier the exploration of small vessels, (4) its better elasticity compared to resins, (5) and finally its availability in a range of colors making it a material of choice for vascular system dissections including those with very small caliber vessels.

Optical three-dimensional scanning acquisition of the position of osseointegrated implants: an in vitro study to determine method accuracy and operational feasibility.

PURPOSE: Manufacturing complex prosthetic framework on osseointegrated implants requires precision at every step of execution. The purpose of this study was to verify the possibility of applying the technology of image acquisition to determine the spatial position of osseointegrated implants. MATERIALS AND METHODS: An optical three-dimensional scanning technique was employed: its measurement systematic error (bias) was calculated by comparing the results with the detection on a coordinates measuring machine. Measurements were carried out on master casts by doing an in vitro simulation of intraoral conditions. RESULT: This study showed that the bias error value of the three-dimensional optical acquiring system was situated between 14 and 21 microm. CONCLUSION: As far as the accuracy is concerned, it seems possible to use the three-dimensional image acquisition technology as a valid alternative to traditional impression-making procedures. However, the bias levels obtained in this in vitro study will have to be confirmed in a clinical trial.

Dynamic MRI of larynx and vocal fold vibrations in normal phonation.

Dynamic magnetic resonance imaging (MRI) of the larynx and vocal folds during phonation was used for measuring the vertical laryngeal movements and the glottal angle of the vocal folds opening and closing in dynamic phase. The data used in this analysis were taken on 10 healthy volunteers during maximal inspiration and the prolonged phonation of the vowels [i] (as in key), [a] (as in car), [u] (as in loop), and the consonant [sh] (as in ship). The results of our MRI data have demonstrated the difference of the vocal folds movement in relation to the vowel and consonant sounds, with a large glottal opening for [sh] and a narrow opening for [i] and [u], and the difference of the laryngeal position in relation to the vowels, with [a] and [u] having a lower larynx position than [i]. Imaging the larynx's positions and the vocal folds' vibrations is possible using dynamic MRI. This technique permits measurements of laryngeal structures and glottal parameters in dynamic function with multiplanar high-resolution imaging. Analysis of laryngeal activity and vocal folds' vibration may be helpful for the evaluation of the phonation function and for the understanding of the physiology of vocal production and voice modulation.