A 56 year old male patient presents to the clinic for a routine dental appointment. During intra-oral examination, multiple restorations were noted as follows; pure gold restoration with 16, class V GIC restoration with 13, silver amalgam restoration with 26 and composite restoration with 46. Which of the following tooth is the most likely to feel sensitive during consumption of very hot or cold food by the patient?
Gold has about one tenth the heat capacity of dentin, about 500 times the thermal conductivity, and about 600 times the thermal diffusivity. Thus a pure gold filling would provide the tooth pulp with very little protection against thermal shock as compared with natural dentin. 
Key concept: Both thermal conductivity and thermal diffusivity are important parameters in predicting the transfer of thermal energy through a material. Because of the rapid changes in temperature that can occur during ingestion of hot or cold foods and liquids, the thermal diffusivity of a dental restorative material may be more important than its thermal conductivity.
16
13
26
46