Which term describes the horizontal space between the upper and lower incisors?

The term that describes the horizontal space between the upper and lower incisors is overjet. Overjet specifically refers to the distance measured in millimeters from the incisal edge of the upper incisors to the incisal edge of the lower incisors when the mouth is in a rest position or during a normal bite. An increased overjet can indicate specific dental conditions such as protrusion of the upper incisors or retrusion of the lower incisors.

Overbite, on the other hand, refers to the vertical overlap of the upper incisors over the lower incisors, which is a different measurement than overjet. Crossbite involves one or more of the upper teeth biting inside the lower teeth, affecting the alignment and positional relationship rather than a measurement of space. Protrusion refers to the forward positioning of teeth rather than a measurement between them.

Understanding these specific terms is pivotal for dental professionals, as they provide insight into the occlusion and alignment of a patient's teeth, which is crucial for effective treatment planning.