Hypodontia

 

Hypodontia:

Results from disturbances during the initiation and proliferation of tooth formation (Formation of dental lamina)

Alternative terminology: Hypodontia, Oligodontia, Anodontia

Hypodontia, Oligodontia, Anodontia are terms that can be interpreted to refer to progressive degrees of missing teeth.

Hypodontia is preferred because it is inclusive of any number of missing teeth.

Oligodontia refers to six or more missing teeth.

Anodontia refers to the complete absence of teeth.

It is implicit in all cases that the teeth are missing because of failure of development.

The term “Congenitally missing teeth” is a misnomer when applied to permanent dentition because these teeth do not commence development until after birth (and with regard to the primary dentition one cannot determine this clinically at birth).

 Some degree of hypodontia is not uncommon, occurring sporadically or with a hereditary component.

The teeth most commonly absent are the last teeth in each series (i.e. the lateral incisor, the second premolar, and the third molar).

(Upper lateral incisor, Lower second premolar, third molars (Upper&Lower), and less commonly, Lower central incisors.

Absence of a deciduoud tooth os quite rare but when it occurs the upper “B” is most commonly affected.

Multiple missing teeth in particular should lead to questioning regerding other affected family members.

The presence of a rudimentary or conical tooth may be associated with the absence of the same tooth on the opposite side of the arch. A common example of this is the peg lateral incisor. Furthermore, that lateral incisor itself may be absent in subsequent generations. Missing teeth are also a manifestation of many syndromes of the head and neck.

Frequency

Primary teeth ~0.1-0.7% Male:Female Ratio unknown

Permanent teeth ~2-9% Male:Female 1:1.4

Third molars > maxillary lateral incisors > second premolars > mandibular central incisors.

Major conditions manifesting hypodontia

Hypodontia is a major clinical feature of over 50 syndromes. These include:

  • Ectodermal Dysplasia
  • Clefting
  • Trisomy 21 (Down’s Syndrome)
  • Chondroectodermal dysplasia (Ellis-van Creveld syndrome_
  • Rieger syndrome
  • Incontinentia pigmenti
  • Oro-facial-digital syndrome
  • Williams’ syndrome
  • Craniosynostosis syndromes

Management:

The aim of treatment is to provide adequate function, maintain the vertical dimension and restore aesthetic appearance.

Ideally, for social reasons, treatment should begin at around 2-3 years of age.

A first step is often the placement of composite restorations to mask the ‘fang-like’ appearance of the caniniform anterior teeth. There is often considerable parental pressure to ‘normalize’ the appearance and later steps may involve the provision of dentures to reduce the likelihood of teasing, often at about the time that the child starts school.

This can begin as soon as the child will allow an adequate impression to be taken.

Often, however, the first set of dentures is initially worn in the pocket(!), but as the child grows there is often a desire to have a more ordinary appearance. With encouragement and positive reinforcement, most children will soon try their new appliances.

Treatment planning for children with hypodontia:

Treatment planning should be multidisciplinary and should consider the present and future needs and development of the child, being cognizant of the concerns of the individual and parents.

Treatment options:

  • Acid-etch retained, composite build-ups of conical teeth
  • Composite resin or bonded orthodontic buttons can also be added to provide undercuts for denture clasps and retainers
  • Partial dentures: conventional or over-dentures
  • Surgical exposure of impacted teeth
  • orthodontic management of spaces
  • Laboratory-Fabricated composite veneers, crowns and bridges
  • Osseo-integrated implants (Usually after the cessation of growth)

Example case report, Multidisciplinary Management of Oligodontia

 

Panoramic RadiographOrthodontic phase

Solitary Median Maxillary Central Incisor Syndrome

SMMCI is very rare. It present with a mid-line symmetrical maxillary central incisor.

The condition may also be associated with other mid-line disturbances such as cleft palate, choanal stenosis, or atresia, imperforate anus or umbilical hernia and is probably part of the spectrum of the holoprosencephaly malformation complex.

Of importance in some cases is the association with hypopalsia of sella turcica, pituitary dysfunction, growth hormone deficiency and subsequent short stature.

The syndrome is usually diagnosed on the basis of the dental manifestations. A mutation in the SHH gene (7q36) has been identified in one family but is probable that there is genetic heterogeneity in the condition.

Ultimately,management of the dental anomaly is by orthodontic and prosthdontic means, determined by space considerations. In most cases, the single central incisor is moved to one side of the mid-line with either creation of space for a prosthodontic replacement or the adjacent lateral incisors are recontoured.

 

Sources:

Handbook of Pediatric Dentistry (Cameron .  Widmer)  Third Edition
Occlusion and Clinical Practice, An Evidence-Based-Approach (Klineberg . Jagger)

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