Final answer:
Dental floss is indeed used to check the contacts of both amalgam and composite resin restorations to ensure they are not too tight or too loose, which is true. Amalgams comprise silver, metals, and mercury, while composite resins are aesthetic and mercury-free.
Step-by-step explanation:
The statement that dental floss is used to check the contacts of both amalgam and composite resin restorations is true. Dental floss is essential in ensuring that the interproximal contacts between teeth are correctly restored after a filling procedure. Using floss allows the dentist to confirm that the restoration is not too tight or loose, which could lead to further dental issues. Amalgams are one type of filling material, primarily consisting of silver and other metals, with mercury making up about half of their weight. Despite its effectiveness and durability, the use of dental amalgams has become controversial due to concerns regarding mercury toxicity. Composite resin restorations, on the other hand, are typically used for aesthetic reasons, as the material can be matched to the color of the teeth and is mercury-free.