Effects on oral tissues of asphyxiation caused by cervical compression: The pink teeth phenomenon in Kato’s studies (1941)

The effects on oral tissues of asphyxiation caused by cervical compression were investigated in 203 rabbits by Kiyotoshi Kato, who published four papers in classical Japanese in Kokubyo Gakkai Zasshi (now The Journal of the Stomatological Society, Japan) in 1941. The aim of this review is to summarize and disseminate the enormous amount of experimental data (reprint permission in English has been obtained from the journal). Based on the experimental models of hanging, strangulation with an external force equal to body weight, and strangulation with an external force equal to 1/10th body weight, the macroscopic and histological findings of the oral region immediately after death, including the respiratory condition until death and ocular conjunctival petechiae, were obtained and compared with 4 cases of human strangulation. Strangulation after each of four physical conditions (anesthesia, starvation, alcohol intake, and bleeding) was also investigated. Experiments were performed to investigate the effects of tracheal obstruction, cervical vein ligation, common carotid artery ligation, cervical nerve amputation, or combinations thereof. In the discussion focusing solely on tooth discoloration, it was suggested that the presence of pink teeth at a stage when putrefaction has little or no effect might be a finding indicative of death from asphyxiation caused by cervical compression. This review provides detailed data on the condition of oral tissues after asphyxiation caused by cervical compression and is expected to be used not only for elucidating the mechanism of the pink teeth phenomenon but also for conducting other forensic research.     

Comparison of different thread products for facial rejuvenation: Materials and barb designs

Background

In recent years, the thread-lifting technique has become widely used in clinical settings. Several thread products are used in clinical practice, and there are many differences between products in terms of many aspects.

Methods

Six commercial thread products were collected and evaluated. The general structure, microstructure, elastic modulus, and strength were evaluated using microscopies and tensile testing in vitro. Seventy-two female rats were divided into six groups. Tissue samples were harvested and histologically evaluated at 1st, 4th, 8th, and 12th week using hematoxylin and eosin and Masson's trichrome staining.

Results

There were differences between products in terms of barb shape, microstructure, elasticity, and strength, and that could be attributed to the materials and barb structures. All threads showed good biological safety, and the density of collagen area in the dermis was increased compared to that in the control group.

Conclusions

This study provided an objective evaluation of barbed thread products, which indicated that all products can be used safely with certain effects in different indications.     

不同螺纹C2椎弓根拉力螺钉系统固定治疗枢椎环骨折的有限元分析

目的：比较半螺纹、双螺纹、全螺纹C2椎弓根拉力螺钉系统固定治疗枢椎环骨折的生物力学特性，为临床选择椎弓根螺钉提供参考。方法：获取1名28岁健康成年男性志愿者的C0～C3节段薄层CT扫描数据，建立正常颈椎C0～C3节段三维六面体网格有限元原始模型。参照既往枢椎环骨折C2椎弓根骨折分型，通过弱化网格单元强度的方法在原始模型上建立A、B、C三种枢椎环骨折模型：A型骨折模型，双侧椎弓根对称性骨折；B型骨折模型，单侧上关节突及椎体后壁骨折，伴对侧椎弓根骨折；C型骨折模型，双侧上关节突骨折，伴椎体后壁骨折。分别用单螺纹、双螺纹及全螺纹椎弓根拉力螺钉系统模拟固定C2-3节段，在模型枕骨髁部施加50N垂直向下压力模拟头颅重力，同时施加1.5N·m力矩使模型加载前屈、后伸、侧屈及旋转四种生理载荷，比较各固定模型在各工况下节点路径上的位移及应力分布情况。结果：固定A型骨折模型后，单螺纹螺钉在各工况下节点路径上的最大位移均小于双螺纹螺钉和全螺纹螺钉；固定B型骨折模型后，单螺纹及双螺纹螺钉各工况下节点路径上的最大位移小于全螺纹螺钉，单螺纹螺钉在前屈、后伸工况下节点路径上的最大位移小于双螺纹螺钉，在侧屈及旋转工...