牙膏管口周围有白色物质的堆积。

There is a white ___build-up around the toothpaste tube opening.

奥运会的筹备工作持续了整整四年。

The ___build-ups for the Olympics lasted for four whole years.

牙医建议每天刷牙两次，以防止牙菌斑的堆积。

The dentist recommends brushing twice daily to prevent ___buildup of plaque.