Understanding Deciduous Teeth

• Deciduous teeth function during childhood, are shed, and are replaced by permanent teeth.
• The word "deciduous" comes from a Latin word meaning "to fall off".
• Deciduous teeth emerge in children between the ages of 6 months and 2 years.
• There are 20 deciduous teeth in total: consisting of 10 maxillary and 10 mandibular teeth.
• The deciduous teeth consist of central incisors, lateral incisors, canines, first molars, and second molars, but there are no premolars
• Beginning at the age of 6 years, deciduous teeth are gradually replaced by permanent teeth.
• Common nicknames for deciduous teeth are "primary teeth", "milk teeth", "baby teeth", and "temporary teeth", which denote a lack of importance.
• Deciduous teeth function in the mouth for about 6 months (mandibular central incisor) to 10 -12 years (C & E).
• Deciduous teeth function in proper alignment, spacing, and occlusion of permanent dentition.
• Premature loss of deciduous teeth can cause destructive results and should be avoided.

Functions of Sound Deciduous Teeth

• Efficient mastication of food is an important function.
• Maintenance of a normal facial appearance is an important function.
• Clear speech formulation is an important function.
• Maintaining space for the emergence of permanent teeth is an important function.

Characteristics of Deciduous Teeth

• Deciduous teeth are generally smaller, whiter, and more consistent in shape than permanent teeth.
• The enamel of deciduous teeth is less mineralized, more permeable, and more easily worn down.
• Deciduous teeth have shorter crowns with respect to their roots.
• The layers of enamel and dentin are thinner in deciduous teeth.
• Pulp cavities are proportionally larger in deciduous teeth than in permanent teeth.
• Pulp horns are higher in deciduous teeth.
• Crowns have a marked constriction at the neck, with enamel that bulges close to cervical lines rather than gradually tapering.
• Deciduous teeth crowns appear bulbous.

Characteristics of Anterior Teeth

• There are no depressions or perikymata on the labial surface of the crowns of the incisors.
• There are no mamelones on the incisal edges.
• The cervical ridge on the facial surface is prominent.
• The cingulum is prominent.

Characteristics of Posterior Teeth

• The molar crowns are narrow buccolingually and wide mesiodistally.
• The molar crowns are short cervico occlusally.
• The molar occlusal surfaces are shallow, with short cusps, unpronounced ridges, and non-deep grooves.
• The buccal cusps are not pointed, and their cusp slopes meet at a very wide obtuse angle.
• There are few grooves or depressions on all surfaces of the crowns.
• The root furcation is near the crown, with little if any root trunk.
• The roots are thin.
• The roots are widely spread to allow for the developing permanent successors.

Maxillary Incisors

• Crowns are short and wide (Length = Width).
• The cervix appears more constricted than in permanent teeth.
• The MI angle is sharp and acute, while the DI angle is obtuse.
• The lingual surface exhibits a prominent cingulum.
• The marginal ridges as well as the lingual fossa are shallow.

Mandibular Incisors

• The crowns are small, narrow, and long.
• The cingulum, lingual ridges, and fossa are poorly developed.
• The incisal edge lies on the long axis.
• The incisal angles are sharp.
• The roots of mandibular incisors are long, thin, and straight.

Maxillary Canine Characteristics

• The tooth is smaller, but is easily confused with the permanent canine because of its large crown and thick labiolingual proportions.
• The crown may be as wide as it is long.
• The crown is constricted at the cervix, more so than incisors.

Labial Aspect of Maxillary Canine

• The mesial cusp slope is longer than the distal one (opposite of the permanent canine).
• The labial surface is strongly convex, particularly at the cervical one-third.
• A longitudinal ridge (labial ridge) connects the cervical ridge with the cusp tip; shallow grooves lie on either side.
• The root is the longest of the deciduous teeth; it may be more than twice the crown length.

Lingual Aspect of Maxillary Canine

• The crown has well-developed cingulum, mesial and distal marginal ridges as well as cusp ridges.
• All ridges are less prominent than in permanent canines.

Mesial and Distal Aspects of Maxillary Canine

• The cervical third of the crown is thicker than in deciduous incisors.
• There is a prominent labial cervical ridge.
• The root is bulky in its cervical and middle thirds, tapering most in the apical third.

Incisal Aspect of Maxillary Canine

• The outline form is diamond shaped.
• The cusp tip is distal to the center of the crown.
• The crown is broader labiolingually than the incisors.
• It is wider mesiodistally than labiolingually.

Mandibular Canine

• The mandibular canine crown is shorter than the maxillary canine.
• The crown is much longer than it is wide.
• The cusp tip may be pointed like an arrow.
• All ridges are not as pronounced as those on the maxillary canine.
• The mesial cusp slope is shorter than the distal cusp slope (opposite to the maxillary deciduous canine).
• The root is at least 2 mm shorter than the maxillary canine.