A Dental Student’s Guide to… extraction of primary teeth

Hannah Hook breaks down the guidance around the extraction of primary teeth, including balancing and compensating extractions.

Hannah Hook breaks down the guidance around the extraction of primary teeth, including balancing and compensating extractions, and how to minimise early space loss.

Primary teeth with poor prognosis may require extraction some time before their natural exfoliation.

However, a dilemma is posed as to whether only the poor prognosis tooth should be removed, or a balancing/compensating extraction should also be carried out.

The British Society of Paediatric Dentistry (BAPD) have created a document with guidance regarding the extraction of primary teeth. This aims to help minimise the effect of early space loss and the associated consequences and help to assist in decision making.

This article will focus on the guidance given in this document.

Compensating extractions

Extraction of the same tooth from the opposing quadrant in the opposing arch
Designed to maintain occlusal relationship and minimise occlusal interference.

Balancing extractions

Extraction of the same tooth from the opposite side of the same arch
Designed to minimise centreline shift
Compensating extractions are more difficult to justify than balancing extractions.

Development of the primary dentition

There are three features which indicate good development of the primary dentition.

These are:

Incisor spacing: Indicative of proper alignment in the permanent dentition
Anthropoid/primate spaces: Naturally occurring spaces between the primary teeth. Usually between the lateral incisors and canines in the maxilla, and the canines and first molars in the mandible
Straight/mesial or mesial step: The distal aspect of the upper second molar is ahead (mesial) of the distal aspect of the lower second molar.

Leeway space

The primary canines and molars are larger than the succeeding permanent canines and premolars
The difference in the mesio-distal width between these primary and permanent teeth is termed the leeway space
The leeway space can be assessed by comparing the size differences between the first and second primary molars. The first primary molar is usually equal in size to the first premolar replacing it. The second primary molar is much larger than its premolar successor. This is known as e-space
E-space is usually around 2.3mm in the maxilla and 2.5mm in the mandible.

Factors affecting space loss

Degree of crowding is one factory that can affect space loss. Direct relation to extent and rate of space loss following primary tooth extractions
The age of the child can also affect space loss. This is because the younger the child is and therefore the earlier the tooth is lost, the greater the opportunity for the remaining teeth to drift
Space loss is also affected by the type of tooth extracted. Depending on the tooth extracted, a centreline shift may be caused or nearby teeth may drift.

Extraction of primary teeth

Radiographic assessment

This should be carried out prior to extraction of primary molars to allow assessment of the presence, position and formation of the developing permanent successors.

Primary incisors

While the early loss of primary incisors can affect appearance, it has little effect on the permanent dentition
Balancing and compensating extractions are not necessary.

Primary canines

Early loss will likely have an influence on the centre line unless there is a lot of spacing present
Early extraction may result in distal drift of the anterior teeth and mesial drift of the posterior teeth. This can result in a centreline shift and displacement of permanent teeth
In spaced dentitions the centreline is unlikely to be affected
In patients with a crowded dentition there is more need for a balancing extraction.

First primary molars

In a crowded arch a balancing extraction may be required
Early extraction may cause distal drift of the anterior teeth and mesial drift of the posterior teeth, resulting in a centreline shift and displacement of permanent teeth
Compensating extractions are not necessary.

Second primary molars

Removal of a second primary molar will not influence the centreline
Balancing extractions are not required.

Considerations

In patients who have experienced early loss of canines or first primary molars and have not undergone a balancing extraction, one of three situations may occur:

There is no centreline shift. In this case, a balancing extraction is not required
Centreline shift with complete space closure. Balancing extraction should be delayed until a full orthodontic assessment has been carried out
Centreline shift with mesial space remaining. The patient should be monitored to determine whether the teeth are continuing to move – if so, an orthodontic opinion is advised.

Space maintainers

The retention of primary teeth is the best space maintainer. Therefore, every effort should be made to retain the primary molars until the time of natural exfoliation.

Consideration on whether or not to provide a space maintainer following an enforced extraction should include weighing up the risks versus the benefits of the provision.

Space maintainers can also help in balancing the occlusal disturbance which may result from not using one.

In addition, the oral hygiene of a patient should be taken into consideration. This is because poor oral hygiene is a contraindication as the appliances can also result in plaque accumulation and caries.

Situations

The maintenance of space following the early loss of a tooth is most important in two scenarios:

First primary molars with severe crowding (less than 3.5mm) per quadrant where a primary first molar has been lost. Space loss caused by drift may result in crowding so severe that the extraction of a premolar may not provide enough space. As a result, orthodontic treatment in the future may be more difficult
Primary second molar has been lost (except in spaced arches).

Types of space maintainer

Natural tooth: Even teeth which are badly decayed, they may be able to be restored, potentially enabling them to maintain space for a few more years
Band and loop: Band and loop space maintainers are the design of choice for a space left by a single tooth. This is a non-functional and fixed space maintainer. A band is placed around the remaining healthy tooth, with a stainless-steel wire loop that extends across the space which has been left by the extracted tooth
Palatal or lingual arch: Useful for patients with bilateral spaces. Studies have demonstrated lingual arch space maintainers to be successful in maintaining arch perimeter. This is also a non-functional and fixed space maintainer. Palatal or lingual arch space maintainers consist of bilateral bands placed around the first permanent molars which connect to a heavy gauge wire adapted to the lingual/palatal aspect of the anteriors
Upper removable appliance: Unless being used for active orthodontic treatment too, this should be avoided.

Contact [email protected] for references.

Catch up with Hannah’s previous Dental Student Guides to…

Follow Dentistry.co.uk on Instagram to keep up with all the latest dental news and trends.