Ligature A means of tying the archwire to the bracket. It may be made of rubber or wire.

Lingual Braces A type of fixed braces where brackets are placed on the tongue side of the teeth.

Lip Bumper A component added to a fixed appliance. It sits inside the lip, is attached to the back teeth, and allows the force from the muscles of the lip to be transferred to the back teeth.

Malocclusion A general term for poor alignment of teeth or jaws. May be due to any combination of spacing, crowding or poor bone relationships.

Malocclusion - Class I malocclusion Where the upper and lower jaws are well balanced but the teeth are crowded or spaced.

Malocclusion - Class 2 malocclusion Where the upper jaw is relatively far forwards compared to the lower jaw. Crowding or spacing of the teeth may be superimposed on this adverse jaw relationship.

Malocclusion - Class 3 malocclusion Where the lower jaw is relatively far forwards compared to the upper jaw. Crowding or spacing of the teeth may be superimposed on this adverse jaw relationship.

Molar The large teeth at the back of the mouth. The first molar usually erupts at about age 6 and is mistakenly thought by parents to be the last “baby tooth”. The average person has 3 molars on each side, upper and lower, and so has 12 molars in all. The third molar is what is commonly called the wisdom tooth.

Moulds A term incorrectly used to refer to either study models or work models.

Openbite When there is a gap between the upper and lower teeth when the back teeth are biting together.

OPG See Panoramic X-ray

OPT See Panoramic X-ray

Overbite The vertical overlap of the upper front teeth over the lower front teeth.

Overjet The horizontal distance between the upper and lower front teeth - i.e. how far forwards the upper incisors are.