Dental Anatomy definitions

Crown elevations

Cingulum A bulbous convexity on the cervical third

of the lingual surface of an anterior tooth

Cusp A pronounced elevation on the

occlusal surface of a tooth, terminating in a conical, rounded or flat surface

Any crown elevation which begins calcification as an independent centre

Mamelon A rounded or conical prominence on

the incisal ridge of a newly erupted incisor

Ridge A linear elevation on the surface of

a toothTypes:

1. Marginal ridges: elevated crests at the mesial and distal margins of

i. The occlusal surfaces of posterior teethii. The lingual surfaces of anterior teeth

2. Triangular ridges: prominent elevations, triangular in cross-section, which extend from the tip of a cusp towards the central portion of the occlusal surface of a tooth

3. Cusp ridges: elevations which extend in a mesial and distal direction from the cusp tips

Cusp ridges form the buccal and lingual margins of the occlusal surfaces of posterior teeth

4. Incisal ridge: the incisal portion of a newly erupted anterior tooth

5. Oblique ridge: an elevated prominence on the occlusal surface of a maxillary molar extending obliquely between the tips of the distobuccal and mesiolingual cusps

6. Transverse ridge: It is made up of the triangular ridges of a buccal and lingual cusp which join to form a more or less continuous elevation extending transversely across the occlusal surface of a posterior tooth

Tubercle A slightly rounded elevation on the

surface of a tooth, e.g. lingual tubercle of maxillary anterior teeth

Crown depressions

Fossa A rounded or angular depression on

the surface of a tooth1. Lingual fossa: a broad shallow

depression on the lingual surface of an incisor or canine

2. Central fossa: a relatively broad, deep angular valley in the central portion of the occlusal surface of a molar

3. Triangular fossa: a comparatively shallow pyramid-shaped depression on the occlusal surfaces of posterior teeth located just within the confines of the mesial and/or distal marginal ridges

Groove A shallow linear depression on the

surface of a tooth1. Developmental groove: marks the

boundaries between adjacent cusps and other major divisional parts of a tooth

2. Supplemental groove: an indistinct linear depression, irregular in extent and direction, which does not demarcate major divisional portions of a tooth

Pit A sharp, pointed depression usually

located at the junction of two or more intersecting developmental grooves or at the termination of a single development groove

Sulcus An elongated valley in the surface of

a tooth formed by the inclines of adjacent cusps or ridges which meet at an angle

Fissure A cleft or crevice in a tooth surface

thought to result from the imperfect fusion of the enamel of adjoining cusps or lobes

Some more definitions Lobe: Primary anatomical division of

the crown of a tooth

Contact area Point or area of contact between two

adjacent teeth, except the most distal tooth in the arch

The contact is always between a mesial surface and a distal surface, except between the two central incisors, where mesial surface contacts mesial surface

Contact areas increase in size with age – after eruption the initial contact approaches a point in size, but with age it broadens because of interproximal attrition, as a result of which the mesiodistal length of the arch is decreased, the teeth become narrower mesiodistally and move mesially (mesial drift)

Proper location of contact areas is important for stabilizing the arch

Also for food flow pattern Food is prevented from slipping

between the teeth – chronic food impaction can lead to inflammation of gingiva, periodontium and bone loss

General rules regarding contact area

1. Contact areas become more cervically located from anterior to posterior in each quadrant

2. In each tooth, the distal contact area has a more cervical location than the mesial

3. The relative size of the contact area increases from anterior to posterior in each quadrant

4. Anterior teeth have contact areas that are centred in the facio-lingual direction

5. Posterior teeth have contact areas which are normally located to the buccal of centre in the facio-lingual dimension

Interproximal spaces It is the triangular-shaped areas between

adjacent teeth in the same arch cervical to the contact area

It is filled with the interdental papilla of the gingiva

The triangle is formed by the alveolar crest at the base, proximal surfaces of adjacent teeth at the sides the contact area of adjacent teeth at the apex

The size and shape of the interproximal space depend on its location

The triangular shape is important for proper stimulation of the periodontium, aiding in self-cleansing

Embrasures An embrasure is the open space

between the proximal surfaces of two adjacent teeth in the same arch, where they diverge facially or lingually, and incisally (occlusally) or cervically from the contact area

They are named according to location From the facial aspect: Occlusal

embrasure and cervical embrasure (which corresponds to the interproximal space and is usually larger than the occlusal embrasure)

From incisal or occlusal aspect: Facial (labial / buccal) and lingual embrasure

Embrasure space should be symmetrical – for esthetics (in anteriors) and for the health of the periodontium – this is an important consideration while planning restorations

Physiologic purposes of proper embrasure form: Serves as a spillway for food during

mastication Integral part of the self-cleansing process of

the teeth Both are interrelated and complement

each other in protection and stimulation of the periodontium

General rules regarding embrasures

From the facial or lingual aspect, incisal (occlusal) embrasures increase in relative size from anterior to posterior teeth

From the facial or lingual aspect, cervical embrasures decrease in relative size from anterior to posterior teeth

From the incisal aspect, the labial and lingual embrasures are nearly equal in size in the anterior teeth

From the occlusal aspect, the lingual embrasure is normally larger than the buccal embrasure in the posterior teeth

When one side of the embrasure (tooth outline) has a certain contour, the other side will normally have a similar contour

Relation between contact area and embrasure: As contact area becomes more cervically

located, occlusal embrasure increases and cervical embrasure decreases in size

As contact area becomes more buccally located, lingual embrasure increases and buccal embrasure decreases in size

Heights of contour It is the area of greatest curvature

inciso (occluso) cervically of the facial and lingual surfaces

Also called ‘crest of curvature’ It aids in proper protection and

stimulation of the gingival tissue

General rules regarding height of contour

On facial surfaces, the heights of contour of all anterior and posterior teeth are located in the cervical third

On lingual surfaces - In anterior teeth, the heights of contour are

located in the cervical third In posterior teeth, the heights of contour are

located in the middle or occlusal third On the proximal surfaces, they coincide

with the contact areas