Novel double-layer Silastic testicular prosthesis with controlled release of testosterone in vitro, and its effects on castrated rats.

Testicular prostheses have been used to deal with anorchia for nearly 80 years. Here, we evaluated a novel testicular prosthesis that can controllably release hormones to maintain physiological levels of testosterone in vivo for a long time. Silastic testicular prostheses with controlled release of testosterone (STPT) with different dosages of testosterone undecanoate (TU) were prepared and implanted into castrated Sprague-Dawley rats. TU oil was applied by oral administration to a separate group of castrated rats. Castrated untreated and sham-operated groups were used as controls. Serum samples from every group were collected to measure the levels of testosterone (T), follicle-stimulating hormone and luteinizing hormone (LH). Maximum intracavernous penile pressure (ICPmax) was recorded. The prostates and seminal vesicles were weighed and subjected to histology, and a terminal dexynucleotidyl transferase-mediated UTP nick end labeling (TUNEL) assay was used to evaluate apoptosis. Our results revealed that the weights of these tissues and the levels of T and LH showed significant statistical differences in the oral administration and TU replacement groups compared with the castrated group (P < 0.05). Compared with the sham-operated group, the ICPmax, histology and TUNEL staining for apoptosis, showed no significant differences in the hormone replacement groups implanted with medium and high doses of STPT. Our results suggested that this new STPT could release TU stably through its double semi-permeable membranes with excellent biocompatibility. The study provides a new approach for testosterone replacement therapy.

[Comparison of the shaping ability of three Ni-Ti rotary instruments in the preparation of simulated curved root canals].

PURPOSE: To compare the shaping ability of three rotary Ni-Ti instruments in simulated root canals. METHODS: A total of 30 simulated resin blocks were divided randomly into 3 groups: ProTaper Universal, ProTaper Next and TF Adaptive. Each group consisted of 10 root canals. The preparation time and changes in canal curvature were measured. Pre- and post-instrumentation photograghs were taken by precise camera and superimposed through Photoshop. The material removed from the inner and outer canal walls at 9 points beginning at 0 mm from the foramen were measured with Image Pro Plus. Centering ability was determined accordingly. The data was analyzed with SPSS13.0 software package. RESULTS: During root canal preparation, no instruments fractured. ProTaper Next was much faster than ProTaper Universal(P<0.05). At the apical curvature, transportation was the least with TF Adaptive, followed by Protaper Next (P<0.05). There were no significant differences in 3 groups with respect to coronal curvature transportation (P>0.05). CONCLUSIONS: Under the conditions of this study, ProTaper Next was the most efficient instrument. TF Adaptive and Protaper Next showed better shaping ability. In general, all the instruments respected original canal curvature well and were safe to be used.