Anodontia and congenitally missing teeth

The congenital absence of teeth (anodontia) causes particular problems because each tooth has an important role to play in the dental arch and having one or several teeth missing creates space that can have significant esthetic and functional consequences.

Terminology

• Anodontia is the congenital absence of all the teeth. (Note: some use this term to indicate a congenital absence of only teeth; partial anodontia).
• Oligodontia refers to the congenital absence of less than 6 teeth (excluding the wisdom teeth) whereas
• Hypodontia indicates the absence of more than 6 teeth.¹

Prevalence

• In theory, any tooth can be congenitally missing, but having certain teeth that do not form (where the tooth bud is absent) is rare.
• The most common genetically missing teeth are the wisdom teeth (25-35% of the population), the upper lateral incisors (± 2%) and the lower second premolars (± 3%) followed by the upper second premolars.
• Women are 4 times more affected by this anomaly than men (4:1 ratio).
• The absence of one or several wisdom teeth rarely has a significant impact on the dentition, the occlusion and function because most of the time, these teeth do not erupt and must eventually be extracted. If they come out, they are often partially erupted, not functional and must nonetheless be extracted due to potential mid-term or long-term problems with which they can be affected. To learn more on wisdom teeth and their influence on dentition and occlusion.
• Temporary teeth can also be genetically missing in 1% of people (affecting both women and men equally) and 30-50% of those with missing temporary teeth will have missing permanent teeth, as well.
• According to studies, between 3.5–6.5% of people have at least one congenitally missing tooth (excluding the wisdom teeth).

Missing teeth dilemma!

The dilemma that the orthodontist must face when he plans on correcting a malocclusion presenting congenitally missing teeth is to decide whether these teeth must be prosthetically replaced after the orthodontic treatment or not. This decision is often made with the general dentist and the patient (or his/her parents). Two alternatives are possible:

1- Prosthetic replacement of the missing teeth. This often requires the reopening of the space to obtain a width that is equivalent to the width of the tooth to replace if the adjacent teeth to the missing tooth have moved and space was lost.

2- Complete space closure where there are missing teeth. In certain cases, it may be possible to attempt to close all the spaces to avoid the need for a prosthetic replacement (bridge, dental implant, removable partial prosthesis, etc.). This can require the use of particular appliances and mechanics, such as temporary anchorage devices or mini-screws.

Upper lateral incisors

• The situation is different with missing upper lateral incisors. These teeth are located in the most esthetic area of the mouth and smile, and their absence often causes dental displacements, asymmetries and unesthetic spaces.
• The lateral incisors are right beside of the canines, and their absence can allow the canines to migrate forward and prevent them from playing their important functional role in the guidance of the various mandibular and masticatory movements. To learn more on impacted and ectopic canines and their functional role.

➡ To learn more on options of treatment for missing upper lateral incisors.

15-year-old teenager with both congenitally missing upper lateral incisors. (A) Before the orthodontic treatment, the central incisors had moved to the sides and the canines migrated toward the midline, creating several unesthetic spaces (see smile in (G)). (B) After the orthodontic treatment, the spaces were consolidated for the eventual replacement of the lateral incisors by dental implants after growth is completed. A retention wire is bonded to the internal face of the central incisors to maintain them into place. (C) A removable clear retainer with prosthetic teeth that replace the lateral incisors. (D) Removable partial prosthesis made by the general dentist. This prosthesis is more esthetic and can be worn while eating. (E) Once facial growth is completed, dental implants were placed with temporary crowns (note the gingival inflammation). (F) Final crowns and good healing of the gingiva. (G) Smile before the orthodontic treatment, (H) after orthodontics, (I) with the removable retainer as in (C) and (J) the final result with the implants and the final crowns.

Lower premolars

Page en construction

Other teeth

The absence of lateral incisors can affect one or both sides at the same time. If a lateral incisor is missing and the other one is present, it will frequently be of a smaller size (peg shape teeth) or misshapen. These anomalies have a genetic cause and therefore, they are frequently observed in several members of the same family.

➡ Dernière mise-à-jour : 2017-10-30 à 18:38:50 – © Jules E. Lemay, www.ortholemay.com – Tous droits réservés / All rights reserved Publication originale : Apr 14, 2013 @ 13:56

ref. :
1- Review Article; Hypodontia: An Update on Its Etiology, Classification, and Clinical Management
Azza Husam Al-Ani, Joseph Safwat Antoun, William Murray Thomson,Tony Raymond Merriman, and Mauro Farella, BioMed Research International, Volume 2017 (2017), Article ID 9378325, 9 pages
https://doi.org/10.1155/2017/9378325
2- http://en.wikipedia.org/wiki/Hypodontia