Anatomical landmarks are features on the surface
of the tooth which are either elevations or depressions. These landmarks help the tooth in
performing their functions and also in their identification. Here we will be discussing the
landmarks showing only convexity or elevation. Cusp. Cusp is an elevation on the crown
portion of a tooth making up a divisional part of the occlusal surface. Each cusp represents a
developmental lobe of the tooth. Cusps are present on the occlusal surface of all molars, premolars
and on the incisal surface of canines. There are different number of cusps in different teeth.
Canines have 1 cusp, premolars have 2 cusps except for mandibular 2nd premolar which may have 2 or 3
cusps, maxillary and mandibular 1st molars have 5 cusps and 2nd molars have 4 cusps. The cusps are
named according to their location on the tooth. For example, in premolars 1 on the lingual side is
lingual cusp, 1 on the buccal side is buccal cusp. Another example in molars, there are on 4 corners
of the occlusal surface so mesio-buccal cusp, disto-buccal cusp, mesio-lingual cusp and
disto-lingual cusp. The shape of the cusp is like a 4-sided pyramid. This shape is due to the
4 ridges running from the cusp tip in different directions. 2 cuspal ridges, 1 mesial cuspal ridge
and 1 distal cuspal ridge. Then 1 ridge which runs to the cervical line, it may be buccal ridge or
lingual ridge depending on the surface on which it is present and 1 triangular ridge running
towards the center of the occlusal surface. Cingulum. Cingulum is a mound or elevation on
the cervical third of the lingual surface of anterior teeth. In a tooth formed of 4 lobes,
it is the lingual developmental lobe that forms the cingulum. Cingulum is seen in all maxillary
incisors, mandibular incisors and in all canines. They are always on the lingual surface
and are limited in the cervical third. If we compare their sizes the largest
cingulum is seen in maxillary canine. Ridges. Ridge is a linear elevation on the tooth.
They are named according to their location or shape or direction on the crown. 1st labial or
buccal ridge. They are present on all canines and on all premolars. It is the ridge that runs on the
facial surface from cusp tip to the cervical line. In canines they are called labial ridge,
in premolars they are called buccal ridge. Lingual ridge. It is a ridge seen in canines
and premolars and runs on the lingual surface. In canines it runs from the cusp tip to the
cingulum and splits the lingual fossa into 2. In premolars it runs from the lingual cusp tip to
the cervical line. Next incisal ridge. This ridge is present in all incisors. It is a ridge which
runs mesio-distally on the incisal surface between the meso-incisal angle and disto-incisal angle.
With continuous use the ridge loses its convexity and becomes sharp, then it is called as 'incisal
edge'. Next cuspal ridge. It is seen in all teeth with cusps. That is all molars, premolars and
canines. It runs from the cusp tip in the proximal direction. Each cusp has 2 cuspal ridges, 1
mesial cuspal ridges, 1 distal cuspal ridge. Next marginal ridge. It is the only ridge which
is present in all teeth. It runs on the proximal borders of the tooth. In each tooth there are
2 marginal ridges, 1 mesial marginal ridge, 1 distal marginal ridge. In anterior teeth
there are present on the lingual surface and in posterior teeth they are present on the occlusal
surface. Cervical ridge. It is seen in all molars. It is a ridge which runs mesiodistally in
the cervical third of the buccal surface. In comparison, they are more prominent in
deciduous molars than permanent molars. Triangular ridge. It is present in all premolars
and molars. It is a ridge running from the cusp tip towards the center of the occlusal surface
of the crown. They are so called because of the shape made by the slopes of the ridge. They are
named according to the cusp from which they are originating, like buccal triangular ridge or
lingual triangular ridge. Transverse ridge. It is seen in all premolars and molars. It is not
a separate ridge but formed by the combination of 2 triangular ridges. It crosses the occlusal
surface transversely in bucco-lingual direction. Lastly the oblique ridge. This ridge is
present on all maxillary molars. This is also not a separate ridge but formed by the
combination of triangular ridge of disto-buccal cusp and distal ridge of mesio-lingual cusp.
It crosses the occlusal surface obliquely. Finally mamelons. Mamelons are 3 protuberances
present on the incisal surface of a newly erupted permanent incisor. They are seen in
all permanent incisors. They are formed by the 3 developmental lobes which form the
labial surface of incisors. Namely the mesial, labial and distal developmental lobes.
That is why they are always 3 in number with continuous use of the tooth the mamelones
disappear, making the incisal ridge straight. Mamelons are not present in deciduous
incisors and are many times used as a feature to differentiate a permanent incisor
from a deciduous incisor in children.