Teeth disease & anomalies l Oral pathology MCQs

Teeth disease & anomalies l Oral pathology MCQs (multiple choice question) for dental students

 ABNORMALITIES OF TEETH (DEVELOPMENTAL 
ANOMALIES INVOLVING
ORAL HARD TISSUES)

• The tooth development begins at about the sixth week of the intrauterine life when few cells of the oral ectoderm undergo proliferation and eventually result in the formation of the dental lamina. The odontogenic cells (toothforming) emerge from dental lamina and the later event constitutes the beginning of tooth development. The development of tooth occurs in several stages, namely the :

1.  The stage of initiation (bud stage).
2.  The stage of proliferation (cap stage).
3.  The stage of histodifferentiation (bell stage).
4.  The stage of morphodifferentiation.
5.  The stage of apposition.
6.  The stage of calcification and
7.  The stage of eruption.

 

• Developmental anomalies may occur during any of these developmental stages of teeth, which are, manifested clinically in the later life once the tooth is fully formed. These anomalies of tooth can occur either due to genetic factors or due to some environmental factors, however in few instances, both of these factors could be involved together to cause some defects in the teeth.

 

 

DISTURBANCE IN SIZE OF TEETH
 

MICRODONTIA

 

Definitions

• Microdontia is the condition in which one or more teeth are smaller than normal. It is important to note that the size of both the teeth and the jaws are almost always genetically determined. However wide variations are often seen in the ratio of tooth size and jaw size. Therefore alterations in the size of the tooth are often proportionately variable to the size of the jaw.

Types of Microdontia

 

True Generalized Microdontia

• When all the teeth in both arches are uniformly and measurably smaller than normal the condition is known as true generalized microdontia.
• This is an extremely uncommon condition and can be seen in pituitary dwarfism.
• True generalized microdontia can also be associated with other congenital defects like Down syndrome and congenital heart disease, etc.
• Relative Generalized Microdontia
• Relative generalized microdontia is the condition in which tooth of normal size may look smaller if they are placed in an abnormally large maxilla or mandible.
• In such cases larger size of the jaws give an illusion of microdontia although the teeth are not really small.
• Relative microdontia often exhibits spacing in between the teeth.

Focal Microdontia

• When one or two teeth are smaller than normal it is called focal microdontia.
• Microdontia involving one or two teeth in the dental arch is far more common than the generalized types.
• The affected teeth are often present symmetrically in the jaw and in addition to being miniature in size, these teeth often exhibit alteration in their shape as well.
• Maxillary lateral incisors and maxillary third molars are the most frequently involved teeth in focal microdontia.
• When maxillary lateral incisors are involved, the teeth often appear ‘cone’ or ‘peg’ shaped and are often designated as peg laterals.
• These peg laterals carry an autosomal dominant type of inheritance pattern.
• Maxillary and mandibular second premolars may sometimes exhibit microdontia.
• Supernumerary teeth are almost always smaller than the normal teeth and are often conical in shape.
• There are certain situations in which smaller teeth can be found in the mouth, although these conditions may not be truly developmental in nature.

Examples:

• Smaller teeth can be seen in the affected side of the jaw in facial hemiatrophy.
• In gemination or twinning one single tooth germ splits into two during development and gives rise to two separate teeth, which are always smaller than normal.
• Small, conical teeth are often seen in hereditary ectodermal dysplasia.
• Multiple miniature teeth can be found in compound odontome.
• A retained deciduous tooth within the permanent dentition may give an illusion of focal microdontia.

Clinical Significance of Microdontia

• a. In microdontia teeth are often spaced which may be disturbing cosmetically.
• b. If shapes of these teeth are also altered along with microdontia (e.g. peg laterals), it will require immediate correction.
• c. Crown and bridge prosthetic work may be required for esthetic rehabilitation of such teeth.