Application and Testing of Transparent Plastics Used in Airplane Construction

This report concerns the efforts being made to remove the source of danger to passengers arising from the fracturing of silicate glass. Some of the alternatives presented include: single-layer safety glass, multi-layer safety glass, transparent plastic resins. Some of the resins considered are celluloid, cellulose acetates, and mixtures of polymers

First metatarsophalangeal hemiarthroplasty for hallux rigidus

There is a paucity of objective information in the literature about first metatarsophalangeal (MTP) hemiarthroplasty. The authors postulate that it is a reasonable treatment option for severe hallux rigidus in selected patients. Twenty-two elective first MTP hemiarthroplasties were performed on 20 patients that met the inclusion criteria. Pre- and postoperative evaluations were done using the American Orthopaedic Foot and Ankle Society (AOFAS) forefoot score, visual analogue scale (VAS) pain score, range of motion (ROM) measurements, and radiographs. Average ROM and dorsiflexion improved by 15° and 8°, respectively. VAS pain scores improved from 5 to 2.5 after six weeks. Painless ambulation occurred after six weeks, with maximum improvement by six months. After 24 months, two patients had pain at the surgical site interfering with function, leading to an unsatisfactory result that required conversion to arthrodesis. First MTP hemiarthroplasty for severe hallux rigidus can be considered an alternative to fusion in properly selected patients who wish to maintain a functional range of motion

NACA Technical Memorandums

This report discusses the efforts being made to remove the source of danger to passengers arising from the fracturing of silicate glass and some of the alternatives presented include: single-layer safety glass, multi-layer safety glass, transparent plastic resins

Outcomes of visual tooth shade selection performed by operators with different experience

Objective To evaluate the effect of professional experience and lighting conditions on visual shade selection on natural teeth and comparing the visual-shade-selection results with those of instrumental methods. Materials and Methods Shade selection was performed on five maxillary central incisors. The 25 observers were divided into five groups according to their professional experience. Observers performed visual-shade-selection using shade guide (Vita 3D Master, Vita Zahnfabrik, Bad Sackingen, Germany) under two lighting conditions (4000 and 6500 K) from the cervical, middle and incisal thirds of the teeth. Same teeth were measured using an intraoral scanner (Trios 3Shape, Copenhagen, Denmark) and spectrophotometer (Vita Easyshade Compact, Vita Zahnfabrik, Bad Sackingen, Germany), under the same two lighting conditions. Results Visual-shade-selection outcomes were not affected by professional experience under both lighting conditions (P .05). Lighting conditions had no effect on the shade measurement outcomes of visual shade selection, Vita Easyshade Compact, and Trios 3Shape (P > .05). Conclusions Shade measurement outcomes were not affected by the lighting conditions (4000 and 6500 K). The shade measurement feature of the T-3S could be an alternative to V-ES and VSS. Clinical significance This study suggests professional experience and lighting conditions has no effect on visual shade selection. Trios 3Shape could be used for shade determination as an alternative to a Vita Easyshade Compact spectrophotometer