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Use of shell crowns in Hong Kong dental hospital attenders.

In 1984 an oral health survey of Hong Kong adults aged 35-44 years revealed that 15% of subjects presented with metal shell crown restorations, often as components of fixed-bridge reconstructions. The aim of this study was to describe the patterns and means of use of shell crowns, and to describe the patterns of tooth loss in patients who presented with such restorations, attending for treatment at the dental teaching hospital in Hong Kong over a 2-year period. A total of 1563 such patients attended. The records, which included radiographs, of 165 of these patients aged 35 years and above, obtained by means of a systematic sampling frame, were studied by one trained examiner. On initial presentation each patient was found to have a mean of 4.0 shell crowns, 77% of these being components of bridge restorations. The bridges involved a mean of only 3.9 units (retainers and pontics). The tooth type most commonly replaced by a bridge of this type was the first molar. It was concluded that most shell crowns used in this patient group are abutment retainers for predominantly short-span bridge restorations.