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In anatomy
Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its ...
, the Curve of Spee (called also von Spee's curve or Spee's curvature) is defined as the curvature
In mathematics, curvature is any of several strongly related concepts in geometry. Intuitively, the curvature is the amount by which a curve deviates from being a straight line, or a surface deviates from being a plane.
For curves, the canonic ...
of the mandibular occlusal plane
Occlusion may refer to:
Health and fitness
* Occlusion (dentistry), the manner in which the upper and lower teeth come together when the mouth is closed
* Occlusion miliaria, a skin condition
* Occlusive dressing, an air- and water-tight trauma ...
beginning at the canine and following the buccal cusp
A cusp is the most pointed end of a curve. It often refers to cusp (anatomy), a pointed structure on a tooth.
Cusp or CUSP may also refer to:
Mathematics
* Cusp (singularity), a singular point of a curve
* Cusp catastrophe, a branch of bifurca ...
s of the posterior teeth
A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tear ...
, continuing to the terminal molar. According to another definition the curve of Spee is an anatomic curvature of the occlusal alignment of the teeth, beginning at the tip of the lower incisor, following the buccal cusps of the natural premolars and molars and continuing to the anterior border of the ramus. It is named for the German embryologist Ferdinand Graf von Spee (1855–1937), who was first to describe the anatomic relations of human teeth in the sagittal plane.
Details
The pull of the main muscle of mastication, themasseter
In human anatomy, the masseter is one of the muscles of mastication. Found only in mammals, it is particularly powerful in herbivores to facilitate chewing of plant matter. The most obvious muscle of mastication is the masseter muscle, since it ...
, is at a perpendicular angle with the curve of Spee to adapt for favorable loading of force on the teeth.
The long axis of each lower tooth is aligned nearly parallel to their individual arch of closure.
The Curve of Spee is, essentially, a series of sloped contact points. It is of importance to orthodontists as it may contribute to an increased overbite. A flat or mild curve of Spee was essential to an ideal occlusion.Larry Andrews. 1972. ''Six Keys to Normal Occlusion.''
The Curve of Spee is distinct from the Curve of Wilson The curve of Wilson is the across arch curvature or posterior occlusal plane.
Arc of the curve, which is concave for mandibular teeth and convex for maxillary teeth are defined by a line drawn from left mandibular first molar to right mandibular fi ...
, which is the upward (U-shaped) curvature of the maxillary and mandibular occlusal planes in the coronal plane.
The Curve of Spee is basically a part of a circle (8-inch diameter) which has its circumference as the anterior ramus of mandible. Ideally, it is aligned so that a continuation of this arc would extend through the condyles. The curvature of this arc would relate, on average, to part of a circle with a 4-inch radius. It is the only Anteroposterior curve of occlusion.
See also
*Intrusion (orthodontics)
Intrusion is a movement in the field of orthodontics where a tooth is moved partially into the bone. Intrusion is done in orthodontics to correct an anterior deep bite or in some cases intrusion of the over-erupted posterior teeth with no opposing ...
References
Human head and neck {{dentistry-stub