''A bridge too far …''. Case report

An elderly man was assaulted and sustained facial injuries with fractures of the mandible and left zygoma. An unusual complication of aspiration of an intact four-unit metal bridge is reported. Immediate retrieval was done under general anaesthesia by rigid bronchoscopy. The technique is described. The importance of careful clinical and radiographic examination is stressed.     

The myelinated fibre content of human inferior alveolar nerves from dentate and edentulous subjects

A study of the myelinated fibre content of human inferior alveolar nerves was undertaken on groups of nine dentate and nine edentulous subjects. Results show that after all the mandibular teeth have been removed, the myelinated fibre count is reduced but there is no selective loss of any specific-diameter group of fibres.     

Is breast feeding a possible cause of dental caries?

This paper investigates breast feeding of infants as a possible cause leading to the development of dental caries in children. Areas discussed include: the clinical features of breast-milk caries; the relationship of breast feeding to current concepts on the aetiology of caries and advice on management of the problem.     

The use of ultrasonography in the diagnosis of neck lumps

The role of ultrasonography in the diagnosis of neck lumps is explained with particular reference to branchial cysts, chemodectomas, and abscesses.     

The use of magnetic forces in prosthetic dentistry

Recently there has been developed a raze earth/cobalt magnet which possesses exceptional magnetic properties and can be produced in a size suitable for intra-oral use. Preliminary studies have been directed to determine the most effective form of magnet design which could be used to improve denture retention. Breakaway loads of over 200 g have been recorded together with attractive forces of up to 50 g at air-gap separations of 2 mm.     

The nature of the interface between polymethyl methacrylate denture base materials and soft lining materials

Four of the commonly used resilient denture lining materials were investigated. They were of different chemical composition, physical forms and processing cycles. Scanning electron microscope examinations of the interface between the liners and the regular acrylic resin base material were carried out in an attempt to assess the bonding of these materials to the denture base, and to evaluate the reliability of their use. The physical and mechanical bonding properties of the resilient lining materials to acrylics were studied, which included tensile, shear, peel and compression tests to measure the efficacy of the joint between the acrylic and the lining materials and its resistance to various external damaging loads. The effect of water on the liner/denture base interface and on the liner's bonding properties to acrylics was also investigated, and the validity of roughening the tissue surface of the denture base prior to processing the liner was assessed.

The findings point to the advisability of using the acrylic type of soft liners whenever resilient liners are indicated. Roughening the fitting surface of the denture base to which the resilient lining materials are to be applied has a weakening effect on the bond between the lining and the denture base. Long-term exposure of the liners to water has a destructive effect. The infusion of the water into the material leads to swelling and stresses build up at the denture base interface and these tend to promote distortion and reduction in bonding.     

Biomechanical considerations in restoring endodontically treated teeth

Various concepts for dental treatment have been established without appropriate documentation, such as restoration of endodontically treated teeth. Some researchers and dentists strongly recommend including a post with the restoration to strengthen the root. Other studies have indicated that posts may substantially weaken the roots and should be avoided. An additional approach suggested that the post did not improve the resistance to fracture during occlusion and did not support the restoration. Biomechanical problems are analyzed, and a recommended clinical approach is presented.     

Modulation of human neutrophil adherence by oral bacteria

Polymorphonuclear neutrophils (PMNs) comprise over 90 per cent of leukocytes in the oral cavity. Although these phagocytic cells have primary defence roles in the gingiva, their stimulation by micro-organisms may also cause substantial tissue damage due to the release of lysosomal enzymes and oxygen radicals. Adherence of PMNs to the endothelium and their subsequent diapedesis and egress to areas of infection are considered early vital events in the inflammatory process. In this study, oral bacteria were screened to determine their direct effects on PMN activation using an in vitro method of measuring PMN adherence to Dacron fibres. Most of the bacteria investigated increased PMN adherence, indicating their potential to cause tissue damage through the release of PMN lysosomal enzymes and other products. In contrast, Bacteroides species suppressed PMNs, indicating their ability to circumvent the phagocytic cells, thus gaining a potential advantage in dental colonization. The modulatory effects of oral bacteria on PMN activation may have significant roles in the immunopathogenesis of oral disease.