When it comes to children, maintaining the amount of space available in their arch is very important. If space is not maintained, the permanent teeth may not have room to erupt, causing long-term problems that may have complications in the future – such as the permanent premolars ectopically erupting (erupting in a space they aren’t supposed to).

While there are a range of dates when the permanent dentition is supposed to erupt, a permanent tooth will officially erupt when 3/4 of the root has developed. As the permanent tooth erupts, the primary tooth’s roots will resorb and, eventually, the primary tooth will fall out. Space maintenance becomes important when primary dentition falls out at the inappropriate time – sometimes due to trauma or due to congenital defects. For instance, if a child loses his or her primary molars at the age of 9, a dentist would worry about the mesial drift of the permanent first molar (the permanent first molar is the first non-succadaneous tooth to erupt in the permanent dentition).

When should we use space maintainers?

The first rule of space maintainers revolves around the primary second molar – if there is premature loss of the primary second molar, space maintenance should always be considered. The premature loss of the primary second molar can cause a loss of 8 or more millimeters of space loss per quadrant (which occurs more often in the maxilla due to the presence of less dense bone). If the primary incisor is lost prematurely, space maintenance is never needed. If the primary canine is lost prematurely, space maintenance is generally not needed (unless there are already crowding issues to begin with). If the primary first molar is lost prematurely, space maintenance is only indicated if the permanent first molars are erupted and in occlusion. There are various of other situations where space maintainers are indicated, and there are four basic appliances that can be utilized for this issue.

‘The premature loss of the primary second molar can cause a loss of 8 or more millimeters of space loss per quadrant.’

To summarize:

• Primary incisor loss = NO space maintenance
• Primary canine loss = Space maintenance required with overcrowding
• Primary first molar loss = Space maintenance if permanent first molars not erupted/ not in occlusion
• Primary second molar loss = ALWAYS use space maintenance

What are the four basic space maintainers?

If the primary second molar has fallen out before the permanent first molar erupts, then the space maintainer known as a distal shoe should be used. This is a single-tooth space maintainer that prevents the mesial drift of an erupting tooth distal to where it is placed. It’s important to know that this space maintainer may not be able to be used with those individuals who are medically compromised.

Another unilateral appliance is known as the band and loop. A band and loop appliance is indicated when there is a single tooth that has been loss, such as the primary first molar prior to the eruption of the permanent first molar.

When a child prematurely loses their primary molars on both sides of their mouth, but has their permanent first molars, you must prevent the mesial drift of the permanent molars (the drifting of the permanent first molars towards the incisors). This can be accomplished using the Nance or TPA appliance.

The fourth and final space maintainer is known as the lower lingual holding arch. This can be used when the second mandibular primary molars are lost and when the permanent first molars have erupted. This is essentially the same as the Nance appliance, but made for the lower arch.

References:

(n.d.) Space Maintenance in Pediatric Dentistry. Dr. Avanija Reddy and Dr. Craig Hollander. A.T. Still Missouri School of Dentistry and Oral Health.