Final answer:
Thermal stress in dentistry concerns the different expansion rates of dental fillings compared to tooth enamel, which can cause pain and damage. Metal fillings are being replaced by composite fillings with expansion rates closer to teeth to reduce these issues.
Step-by-step explanation:
Thermal Stress and Dental Fillings
Thermal stress occurs when materials expand or contract due to changes in temperature. Dental fillings and tooth enamel typically have different coefficients of expansion, which can lead to discomfort or damage when consuming very hot or cold foods and drinks. Traditional metal fillings, such as gold and silver, expand at different rates compared to teeth, potentially causing cracks and leaks. To mitigate this issue, composite fillings made from porcelain are used as they have a coefficient of expansion that is closer to that of natural teeth, minimizing thermal stress. Understanding thermal stress is essential in not only dentistry but also fields such as engineering where matching expansion coefficients is important for the integrity of structures and medical implants.