Distal Shoe Space Maintainer
Distal shoe appliance is the chairside-fabricated one with the stainless steel crown. It is cost-effective and is an efficacious appliance for the guidance of an unerupted permanent 1st molar in the position after the premature extraction loss of the 2nd primary molar. In this article there is a brief discussion on the distal shoe space maintainer.
Distal Shoe Space Maintainer (Intra-alveolar, Eruption guidance appliance):
- The fixed distal shoe space maintainer was first reported by Willets (1932). The appliance is constructed when there is a premature loss of the second primary molar, prior to the eruption of the first permanent molar. This was a cast gold appliance and soon fell into disfavor due to the increased cost.
- The commonly used one is that described by Roche (1942), a crown or band and bar appliance. The major difference between the two appliances is the gingival extension. The Roche variety had a ‘V’shaped gingival extension while the willets had a ‘V’ shaped gingival extension while the Willets one had a bar type.
-durable, maintains occlusion, can be used after removal of extension.
-costly, time consuming, difficult construction and adjustment.
-easy fabrication, low cost and single abutment.
-more breakage chance, less retentive and new appliance required after eruption of tooth.
Criteria for appliance fabrication:
In the lower arch, the contact area of the distal extension should have a slight lingual position over the crest of the alveolar ridge. By contrast, the area of distal extension of the maxillary appliance should be slightly facial. This is important to prevent rotation of tooth and appliance.
If no adequate width is provided, the tooth may slip. It should be approximately the width of the contact area.
C. Length of the distal extension:
- Ideally, measure the second molar before extraction and remove the same form model.
- If the second molar is already missing, a recommended practice is to measure on a radiograph, the distance between distal surfaces of first permanent molar. This carries the disadvantage of the appliance being over extended, especially in the maxillary arch as the molar erupts from a more distal direction to swing mesially.
- Thus, the best way is to measure M-D width of the second primary molar on opposite side.
D. Depth of gingival extension:
The gingival extension of the appliance should be constructed to extend 1mm below the mariginal ridge so as to just ‘capture’the mesial marginal ridge of the tooth.
- For the functional type if cast gold appliance is used, better to use 2 abutments, as it is functional. But, with space between the canine and the 1st molar, this may not be possible. Thus, a groove placed in the mesiofacial surface with a 691 bur will aid in developing retention.
- For non-functional as it is not able to establish the occlusion, the first molar may tip over the place, at the time of eruption.
The above article discusses about the distal shoe space maintainer. Thus, individuals going for the fixed space maintainer -distal shoe appliance must also consider its indications, contraindications and disadvantages. Gegenhiemer amd Donly have described the distal shoe appliance (fabrication of the laboratory) soldered to the stainless steel crown which required two visits to the dental office by the patient. There are some kits available for the distal shoe appliance (by the Dental Supply, Co, Covina, Calif: Denovo, Arcadia, Calif), in which the distal show appliance can be fabricated and it can be immediately inserted after the second primary molar extraction while the patient is on the chair during the one visit.