The decision for space maintenance should always take into consideration the full picture:

• Oral hygiene

• Compliance

• Prognosis of space maintenance

• Future orthodontics

• Costs (space maintenance now vs potential orthodontics later)

We believe there are two key questions to ask when considering placing a space maintainer:

1. Will space maintenance now alleviate the need for (complex) orthodontic treatment in the future?

2. Will space maintenance reduce the chances of premolar extraction as part of orthodontic treatment.*

*This is not to suggest we are against premolar extractions when indicated. It simply means it would be a shame to lose permanent teeth because a space maintainer was not placed.

Not all children who lose a primary tooth prematurely are necessarily good candidates for space maintenance if there are doubts regarding their ability to maintain adequate oral hygiene.

Sometimes, whether it be related to oral hygiene, compliance, costs, etc., choosing not to space maintain may be best for a certain patient and their family. Informed consent about the pros and cons is paramount.

Even if a tooth is not a suitable abutment (e.g., it had extensive pulp therapy), it may still be worth placing a space maintainer. The reason for this is you may be buying time to allow an M1 to erupt before you are able to place a bilateral space maintainer (e.g., a first primary molar was lost in the mandible, but you want to give the first permanent molar time to erupt).

The key is informed consent—you must warn the parent that it may fail (the tooth or the appliance) and the child may require an additional space maintainer soon.

There is a rule of thumb that if a D is lost after age 8 years, a space maintainer is not necessary.

This may be true, but this decision should not be based on the chronoligical age of the patient. We strongly recommend using the Space Maintenance Calculator to determine the risk of space loss as well as considering the potential impact on occlusion.

If space loss does occur and it complicates an underlying orthodontic issue, it cannot be considered best practice to have not recommend a space maintainer.

Even if some space has been lost, it may be indicated to space maintain. For example, if an E was lost, the M1 drifted mesially 2mm, and the second premolar now has JUST enough space to fit in, you may choose to space maintain to prevent impaction or ectopic eruption.

This is a more difficult decision to make however, and a referral to a specialist may be indicated.

To determine if a tooth is a suitable abutment, consider the following: 

• If there's active caries, restore it first. 

• If there's a risk for future infection (previous pulp therapy or deep caries), this tooth can still be used but must be monitored over time. 

• Mobile teeth are not suitable abutments. 

• For permanent molars, they have erupted enough to place a band.

• Always check for molar hypomineralization of M1s which has the potential to compromise the tooth’s ability to serve as an abutment.  

• Bottom line, you expect this tooth to be stable over time.

Any time you place a unilateral space maintainer (e.g., Band & Loop or Distal Shoe) in a child before the M1s erupt, you should always re-evaluate for a switch to a bilateral space maintainer (e.g., Nance or Lower Lingual Arch).

Reasons to make the switch include:

• Desire to preserve leeway space or arch length for orthodontic reasons.

• In the mandibular arch, placing a LLA could provide space to unravel anterior crowding.

• Concerns about losing an abutment before the permanent successor erupts.

• Other primary teeth will be lost early.

Keep in mind the following differences:

• The sequence of eruption in the Mx (6-1-2-4-5-3-7) vs Md (6-1-2-3-4-5-7) can have implications for exfoliation of abutments.

• The bilateral space maintainer in Md (Lower Lingual Arch) requires the incisors to be erupted before placement. On the other hand, the Mx relies on the anterior palate for anchorage.

• The Md is much less amenable to dental and skeletal expansion than the Mx - use of a LLA may be helpful to resolve crowding.

Rules of eruption to be aware of:

1. Permanent tooth erupts through 1 mm of alveolar bone coverage every 6 months.

2. Premolars erupt when root development is between the 1/2 to 3/4 mark.

if it looks like a permanent second molar may erupt before a second premolar, be aware that the eruptive pressure on the first molar may cause space loss. This may reduce the amount of space for the premolar to erupt into the mouth.

We recommend having a periapical radiograph, or at least an apical bitewing of the area before extracting.

This helps you assess alveolar bone covering and root development of the permanent successor.

Regarding radiographs:

• You should have an x-ray of the area before performing an extraction.

• You need a radiograph to evaluate alveolar bone covering and root formation of the permanent successor.

• If the child is under 8y, you can assume premolar roots are not 65% developed.

• If this child is 8y+, you can assess root development with a periapical radiograph.

• If this child is 8y+ and has not yet had a panoramic radiograph taken to assess development, now would be an appropriate time to take one.

Place the blade as far distally within the extraction socket as possible. It should lie within the follicular space, between the mesial surface of the crown and distal surface of the bony crypt.

Always take a radiograph to verify the correct position of the distal shoe before and after placement.

Also remember that it is often indicated to switch from a Distal Shoe to a LLA or Nance once the M1s have erupted.

Regarding M1s that are “stuck” under an E, there are lots of points to consider:

• The defect on the E will not necessarily lead to infection—even if it appears to be into the pulp.

• You should however always monitor the tooth for infection / abscess.

• A portion of the ectopic M1s will spontaneously correct with time.

• For those that don’t self-correct, a separator or spring can be used for “easy” correction.

• If the situation can’t be easily corrected, consider a referral to a specialist - especially if other issues are present.

• Space maintenance is rarely indicated with ectopic M1s because the situation either corrects or significant space is lost as the E is lost and the M1 erupts.

There is always a chance that putting a band on an E can lead to impaction of an M1 if it is erupting along the distal root of the E. Keep an eye out for this at recall appointments.

For Ds that taper occlusally and would not hold a band well, you have a couple options.

First, if the tooth has caries, you could use a space maintainer that relies on a stainless steel crown in (e.g., a crown & loop) rather than a band - you’ll get the retention from the snap of the SSC.

You could also crown the tooth and place a band appliance (e.g., a band and loop) over top - the shape of the crown will likely be more retentive than the tooth was.

If you are taking an impression of a single quadrant (e.g., for a band & loop), consider using compound only instead of alginate. This will make it easier to stabilize the band before pouring up the model.

An impression that combines alginate and compound can be a useful tool. With the compound present, it’s easier to stabilize the band when pouring up the models.

The steps are as follows: heat compound, place in tray, add alginate before the compound hardens, take the impression. Make sure the compound will surround the teeth that have bands. You can carefully melt a small portion of the compound in the lab to stabilize the band.

Try using ortho wire or a paperclip to stabilize a band within the impression before pouring up the model.

Click HERE to see a copy of the information sheet that Dr. Jeff and his staff give to all parents/guardians of children receiving a space maintainer.

This is important as part of a thorough informed consent process. Clinicians and families of patients alike be aware that after insertion, SMs require monitoring as well as possible adjustments or replacement over time.

If a patient was referred to you for care, they will return to the referring dentist for regular care. It is helpful to send an information sheet to this dentist as well. This will serve as a friendly reminder that appliances should be removed and recemented to maintain oral health - especially if first molars are involved.

SMs should be reviewed by dentists every 6 months to check on the health of abutment teeth and gingival tissues. Evaluate:

• Dental and periodontal health

• Appliance failure

• Interferences with eruption of permanent teeth caused by the SM

• Soft tissue ulceration / embedding of appliances (as a permanent tooth erupts, the ridge expands and this might be more of a concern)

This is especially especially important to consider in children with SMs who often have a history of premature tooth loss related to subpar oral hygiene practices.

Appliances with bands should be removed once per year for:

• Cleaning

• Application of fluoride to abutment teeth

• Recementation if the appliance if still indicated

Most common adverse effects include:

• Dislodged, broken, lost appliances

• Soft tissue impingement

• Cement loss + decementation

• Solder breakage

Maintenance appointments allow most of the aforementioned adverse effects to be managed and overcome.