Line Angles and Point Angles

Line Angles and Point Angles of The Teeth

Tooth surface| Line Angles & Point Angles

To identifying teeth and referring to specificareas of a tooth, it is necessary to utilize named surfaces according to where it is located.

The surface of anterior teeth are: labial, lingual, mesial, distal, incisal. The surface of posterior teeth are: buccal, lingual, mesial, distal, occlusal.

Tooth surface| Line Angles & Point Angles

Facial (F): The surface that faces the cheeks or lips. Labial: The surface towards the lips (incisors and canines).
Buccal (B): The surface towards the cheeks (molars and premolars).
Lingual (L): The surface facing the inside (tongue/palate) of the mouth. 
Proximal: Tooth surfaces that are next to each other (i.e., distal of lateral incisor and mesial of canine). 
Mesial (M): the surface towards the midline of the mouth (anterior tooth).
Distal (D): The surface away from the midline of the mouth (anterior tooth).
Occlusal (O): The biting surface of posterior teeth (premolars and molars). 
Incisal: The biting edge of an anterior tooth (incisors and canines). 
Cervical: The junction between the crown and root.
Gingival: close to or in proximity to gingiva.
Palatal: Next to the palate (maxillary teeth only).
Apical: At the apex of the tooth root.

  • The Crowns of incisors and canines have four surfaces, and the crowns of premolars and molars have five surfaces. 
  • In the anterior teeth the surfaces toward the lips are called) labial surfaces) in the posterior teeth the Surfaces facing the cheek are called (buccal surface).
  • Labial and buccal surfaces together are called (facial or external surface). 
  • All surfaces facing the tongue are called (lingual or internal surfaces). These surfaces may be called (palatal surfaces) in the upper jaw.
  • The surfaces of the posterior teeth, which come in contact with those of the opposite jaw during occlusion, are called (occlusal surfaces). 
  • In the anterior teeth, these surfaces are called (incisal surfaces).
  • The surfaces of the teeth facing adjoining teeth in the same dental arch are called (proximal) or (proximate surfaces) clinically known as (proximal surfaces).
  • The proximal surfaces may be either (mesial) or (distal). Mesial surfaces are the surfaces facing the median line.
  • Distal surfaces are the surface away from the median line. 
  • In each dental arch, the distal surface of each tooth contacts the mesial surface of the tooth posterior to it, except the central incisors whose mesial surfaces contact each others.

Division into Thirds

The crown may be divided into thirds in three directions inciso-or occlusocervically, mesiodistally, and labio-or buccolingually. From the labial or buccal aspect, the crown is divided into an incisal or occlusal third, a middle third, and a cervical third.

The root is divided into a cervical third, a middle third and an apical third. Mesiodistally, it is divided into mesial, middle and distal thirds. Labio-or buccolingually, it is divided into labial or buccal, middle and lingual thirds. 

Tooth surface| Line Angles & Point Angles

Line Angles & Point Angles

The junctions of the crown surfaces are described as line angles and point angles.

Line Angles
The line angle is the line which joins two surfaces. It derives its name from the combined names of these two surfaces. For instance, on an anterior tooth, the junction of the mesial and labial surfaces is called the mesiolabial line angle.

The line angles of the anterior teeth
Tooth surface| Line Angles & Point Angles

The line angles of the anterior teeth are: Mesiolabial, Distolingual Distolabial, Labioincisal, Mesiolingual, Linguoincisal.

The line angles of the posterior teeth

Tooth surface| Line Angles & Point Angles 
The line angles of the posterior teeth are: Mesiobuccal, Distolingual, Bucco-lingual, Distobuccal, Mesio occlusal, Linguo-occlusal, Mesiolingual, Disto-buccal.

Point Angles
The point angle is the point which joins three surfaces. The point angle also derives its name from the combined names of the surfaces it joins. 

For example; the junction of the mesial, buccal and occlusal surfaces of a molar is called the mesiobucco-occlusal point angle.

The point angle of the anterior teeth
Tooth surface| Line Angles & Point Angles

The point angles of the anterior teeth are: Mesiolabioincisal, Mesiolingualincisal, Distolabialincisal, Distolinguoincisal.

The point angles of the posterior teeth
Tooth surface| Line Angles & Point Angles

 The point angles of the posterior teeth are: Mesiobucco-occlusal, Mesiolinguo-occlusal, Distobucco-occlusal, Distolinguo-occlusal.

Actually, there are no line angles, point angles or plane surface on the teeth. They show some kind of curvatures.
google-playkhamsatmostaqltradent