Waldeyer’s ring [H. W. G. Waldeyer (1836–1921), German anatomist] A band of *lymphoid tissue that encircles the *nasopharynx and *oropharynx. It consists of the lymphatic tissue of the pharynx, the palatine *tonsil, and the lingual tonsil, as well as other smaller collections of lymphoid tissue in the region.

wall n. One of the enclosing surfaces of a tooth cavity. It is named after the tooth surface towards which it faces (e.g. mesial, distal, buccal, lingual, gingival, incisal). The enamel wall is that part of the prepared cavity wall that consists of enamel; it meets the external unprepared surface of the tooth (cavosurface) at the *cavosurface angle.

Wand® A computer-controlled dental local anaesthetic injection device. The computer-controlled system maintains constant pressure and volume ratios of the anaesthetic solution regardless of variation in tissue resistance. The system is designed to reduce the incidence of pain during injection.

Ward’s wax carver n. See CARVER.

warfarin n. An anticoagulant used to reduce the risk of thrombosis; it may be prescribed for patients with prosthetic heart valves. Although there is the potential for excessive haemorrhage following dental surgery, patients who require dental surgical procedures in primary care and who have an INR (*international normalized ratio) below 4.0 should continue warfarin therapy without dose adjustment. Trade names: Marevan, Panwarfin, Coumadin, Sofarin.

Further Reading Randall C. Surgical management of the primary care dental patient on warfarin. Dent Update 2005;32 (7):414–16, 419–20,

Perry D., Noakes T., Helliwell P. Guidelines for the management of patients on oral anticoagulants requiring dental surgery. Br Dent J 2007;203:389–93.


Warthin’s tumour See ADENOLYMPHOMA.

Warwick James elevator n. See ELEVATOR.

washer-disinfector An automated machine designed to clean, decontaminate, and thermally disinfect reusable invasive medical devices (RIMD) used in dentistry such as dental instruments. There are a number of automated stages including pre-rinsing, cleaning, interim rinsing, thermal disinfection, final rinsing, and drying. Disinfection is achieved by flushing with water at 90°C (194°F) for 1–10 minutes. The machine is unsuitable for heat-sensitive items. The specification of the washer-disinfector should comply with requirements of EN ISO 15883, parts 1 & 2. Each washer-disinfector should be fitted with an independent process monitoring system in accordance with EN ISO 15883 part 1. When lumened devices, such as dental handpieces, are being reprocessed, the washer-disinfector should be provided with load carriers that permit the irrigation of the lumened device. Washer-disinfectors and accessories should be specified, installed, validated, commissioned, tested, and operated in accordance with EN ISO 15883, parts 1,2 & 5 or UK standard HTM 01–05. Washer-disinfectors should be subject to planned preventative maintenance.

waste n. See CLINICAL WASTE.

water fluoridation See FLUORIDATION.

water irrigator See ORAL IRRIGATOR.

water–powder ratio See RATIO.

wax n. An ester of ethylene glycol and two fatty acids or a combination of other fatty alcohols with fatty acids. Dental waxes are compounds of different waxes combined to provide the appropriate physical characteristics. Baseplate wax is a hard pink wax used for making occlusal rims and for holding artificial teeth to baseplates during the fabrication of dentures; it is composed mainly of beeswax, paraffin, and a colouring agent. Beeswax is a natural wax with a high melting point (62–64°C, 144–147°F) which historically was formerly used in the *lost wax process; it is a constituent of other dental waxes and may be utilized in the manufacture of waxed dental *floss. Bite registration wax is a metal-impregnated (usually aluminium) wax in sheet form; it is used to record the occlusal relationships between a patient’s opposing arches (*occlusal record) and to later transfer this relationship to the cast for articulation; it is hard at mouth temperature. Carding wax is used mainly to form a box around impressions of the mouth prior to pouring a *plaster of Paris or *gypsum stone cast; it is red in colour and soft and pliable at room temperature. Carnauba wax is a hard, high melting point wax used to control the melting temperature of many dental waxes. Disclosing (pressure indicator) wax is painted onto the mucosal surface of a denture to identify areas of unequal pressure; the wax flows away from the area needing relief. Inlay (casting, burnout)

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