Dental hygienists assist dentists in providing oral health therapies and education. They consult with dentists to determine the appropriate treatment for patients, but are able to carry out most procedures independently. They examine patients' teeth and gum for signs of disease, remove plaque build-up and stains, and advise patients on how to look after the teeth and gums to maintain oral health. These workers also take x-rays, make impressions of patients' mouths to make mouth guards and study casts, and select, size and remove orthodontic appliances, such as braces. In some cases, dental hygienists may also assist dentists in surgery.