commonHypodontia/oligodontia might also be associated with cleft lip and palateOver retention of the overlying deciduous tooth (because of the missing permanent tooth germ) occurs frequently
1.1.5 Radiographical Features
In many cases routine radiography may reveal developmentally missing teeth
1.1.6 Diagnosis
History
Clinical examination
Radiography
1.1.7 Management
Prosthodontic treatment/implants or orthodontic treatment for edentulous spaces
1.2 Hyperdontia (Supernumerary Teeth)
1.2.1 Definition/Description
Hyperdontia/supernumerary teeth: excess number of teeth beyond the expected 20 deciduous and 32 permanent teeth
The shape of the supernumerary tooth may resemble a tooth of the normal series. In this case, the extra tooth is called supplemental tooth
1.2.2 Frequency
98% of supernumerary teeth occur in the maxilla
In 1% of the population, a supernumerary tooth occurs in the midline in anterior maxilla; this is called mesiodens
1.2.3 Aetiology/Risk Factors
Budding of the dental lamina: stimulus for budding is not known
1.2.4 Clinical Features
Asymptomatic: supernumerary teeth may be detected incidentally on radiography for other reasons
Supernumerary teeth are five times more common in the permanent dentition than in the deciduous dentition
Supernumerary teeth may be single or multiple, unilateral or bilateral, and may be present in one or both jaws.
The most common single supernumerary tooth: midline of the anterior maxilla, known as a mesiodens. This is also an example of microdontia
Other supernumerary teeth: maxillary fourth molars, maxillary lateral incisors, mandibular fourth molars and mandibular premolars
The most common site for multiple supernumerary teeth is the mandibular premolar region (Figure 1.2)Figure 1.2 Supernumerary premolars located lingual to the mandibular first and second premolars.
A supernumerary tooth lingual or buccal to a molar is called a paramolar
A supernumerary tooth located distal to a third molar is called a distomolar
Supernumerary teeth are common in patients with cleidocranial dysplasia and Gardner syndrome
Complications of supernumerary teeth may include:Delayed or ectopic eruption of adjacent teethRoot resorption of adjacent teethCrowdingMalocclusionDiastemaPericoronal cyst or infection
1.2.5 Radiographical Features
Cone beam computed tomography (CBCT) precisely defines the location of the tooth and its proximity to vital anatomical structures such as the nasal floor and nasopalatine canal
1.2.6 Diagnosis
History
Clinical examination
Radiography
1.2.7 Management
Extraction in most cases
1.3 Microdontia and Macrodontia
1.3.1 Definition/Description
Microdontia: size of the tooth unusually smaller than average
Macrodontia: size of the tooth unusually larger than average
1.3.2 Frequency
Differences in prevalence rates exist
Approximate prevalence in general population:1.58% for microdontia0.03% for macrodontiaMicrodontia in maxillary lateral incisors (‘peg laterals’) is common (0.8–8.4%)
1.3.3 Aetiology/Risk Factors
Maternal influences, genetic and environmental factors.
Deciduous teeth are affected more due to intrauterine maternal influences
Permanent teeth are affected more due to environmental factorsFigure 1.3 Microdontia: maxillary left lateral incisor (‘peg lateral’) is cone shaped and smaller than average for lateral incisor(source: by kind permission of Professor Charles Dunlap, Kansas City, USA).
1.3.4 Clinical Features
Generalized microdontia involving all teeth is extremely rare
Generalized macrodontia is rare: often seen in pituitary gigantism
Generalized microdontia may be a feature of Down syndrome and pituitary dwarfism
Microdontia may be associated with hypodontia
Macrodontia may be associated with hyperdontia
Microdontia is more frequent in females
Macrodontia is more frequent in males
Maxillary lateral incisor is commonly involved in microdontia (peg lateral; Figure 1.3)
Isolated microdontia is frequently seen in third molars
Isolated macrodontia is occasionally seen in incisors, canines, second premolars and third molars (fused and geminated teeth to be differentiated from macrodontia)
1.3.5 Diagnosis
History
Clinical examination
For macrodontia, radiography is useful to rule out gemination or fusion
1.3.6 Management
No treatment is required unless for aesthetic purposes.
Porcelain crown for peg lateral is often used
1.4 Gemination, Fusion and Concrescence
1.4.1 Definition/Description
Gemination: attempt at a single tooth bud to divide, resulting in a tooth with bifid