Fixed Space Maintainers
Fixed appliances are less bulky, easier for patients to accept and manage, and require less
regular care. Follow-up at appropriate intervals is crucial to the removal of the appliance in
accordance with eruption of the permanent successor. They can be classified as unilateral or
bilateral, maxillary or mandibular.
Unilateral space maintainers
BAND AND LOOP
It is indicated to hold molar position when there is a premature loss of 1 st or 2nd primary molar.
The appliance includes a band on the abutment tooth and a wire loop that traverses the
edentulous space. The wire touches the tooth on the other side of the space to hold both teeth
in place and should be wide enough to allow eruption of the permanent tooth.
There are various modifications that can be done for this appliance, such as the use of an
occlusal rest to prevent mesial tipping of the adjacent tooth. This rest could also be bonded into
position for added retention. It may be modified for a long span by utilizing two bands and a
buccal bar with a loop, especially when the paths of insertion of the abutment teeth are not
parallel. Adjustment of the loop also helps to regain a small amount of space.
(taken from Dr. Retrouvey’s private clinic)
Advantages:
Easy for the patient to maintain
Easy fabrication for the clinician
Disadvantages:
Opposing tooth may super erupt. It could be prevented by using an occlusal bar or an occlusal
pad to provide a functional surface for the opposing teeth.
CROWN AND LOOP
It is a variation on the band and loop used when there is premature loss of the 1st or 2nd primary
molar. The abutment tooth often has inadequate tooth structure, or has been restored after a
pulpotomy, the crown being either fitted or provided separately with the impression by the
dentist. A stainless steel wire is soldered to the stainless steel crown and the wire again should
be wide enough to accommodate the eruption of the permanent tooth.
http://www1.umn.edu/dental/courses/dent_5501/images/inter4.jpg
Advantages:
Same as the band loop.
Disadvantages:
More difficult to fabricate than the band and loop.
Fabrication:
1.
2.
3.
4.
5.
Separation of teeth 3 – 5 days before the band fitting appointment
Selection & adaptation of band on the dental cast.
Impression taking with alginate or compound.
Appliance fabrication
Cementation:
- The cements that can be used for luting these appliances are zinc phosphate, zinc
polycarboxylate, ZOE, glass ionomer, resin-modified glass ionomer, compomer and
resin cements. Glass ionomer cements, in particular, have useful fluoride-releasing
properties.
Controversy:
Recently a study has shown that space changes with regard to arch width or arch perimeter 6
months following premature loss of a primary maxillary first molar was minimal. The early
space changes in the maxillary dental arch consist mainly of distal drift of the primary canines
toward the site of the extraction and palatal migration of the maxillary incisors indicating that
the mesial movement of permanent molars might not occur as a consequence of the tooth
extraction. There was statistically significant 1 mm of space loss detected; however, it is not
likely to be of enough clinical significance for the use of a space maintainer. If palatal
movement seems to be needed, a palatal arch was suggested instead of band and loop space
maintainer.
DISTAL SHOE
The distal shoe is indicated in cases where the second primary molar is lost prematurely. This
appliance guides the first permanent molar into place and prevents mesial drifting of the tooth.
The distal shoe has an extension going subgingivally to a location mesial to the unerupted first
permanent molar. It is a successful appliance in guiding unerupted permanent teeth into the
arch but it needs careful supervision. Once erupted, the position of the molar may not always
be favourable. However, this is less of a problem compared to the correction of molar position
that has erupted mesioangularly when no guiding appliance is placed.
http://cudental.creighton.edu/images/Distal%20shoe.jpg
Indications
1. Premature loss or extraction of the second primary molar prior to the eruption of the
first permanent molar
2. Advanced root resorption and periapical bone destruction of the second primary molar
prior to eruption of the first permanent molar
3. A primary second molar with advanced caries that is not restorable
4. Ectopic eruption of the permanent first molar
5. Ankylosis of the primary second molar
Contraindications
1.
2.
3.
4.
5.
Inadequate abutments due to multiple loss of teeth
Poor patient or parental cooperation
Missing permanent first molar
Systemic diseases that affect healing such as diabetes mellitus
Cardiac anomalies that require antibiotic prophylaxis prior to dental treatment
Fabrication
(a laboratory processed appliance soldered to a stainless steel crown that requires two visits by
the patient)
1. Preparation of the tooth serving as retainer for the crown, a stainless steel crown is
adapted to the primary first molars
2. Transfer impression for the appliance fabrication
a. Crown is removed, placed and stabilized into the impression
b. Impression poured in dental stone.
3. Another crown is temporarily cemented
4. Once appliance is fabricated and returned from the lab, a radiograph is taken to
verify position of permanent molar before extraction of the nonrestorable primary
second molar
5. Immediate cementation of the appliance
Bilateral space maintainers
NANCE APPLIANCE & TRANSPALATAL BAR
There are several appliances used to maintain posterior space in the primary dentition.
Whereas the lingual arch is commonly used for the lower arch, the Nance appliance and the
transpalatal bar are the appliances used for the upper arch. These appliances use a large wire
to connect banded primary teeth on both sides of the arch that are distal to the extraction site.
The difference between the two is that the Nance appliance incorporates an acrylic button that
rests directly on the palatal rugae. The transpalatal bar is made from a wire that runs directly
across the palatal vault, avoiding contact with the soft tissue.
A transpalatal arch is best indicated when one side of the arch is intact and several primary
teeth are missing on the other side. In this case, the rigid attachment to the intact side usually
provides enough stability for space maintenance. However, when primary molars have been
lost bilaterally, both permanent molars may tip mesially with a transpalatal arch. A
conventional lingual arch or Nance appliance is preferred in this situation.
ADVANTAGES
NANCE APPLIANCE
DISADVANTAGES
• resistance to anterior • less hygienic
movement of the posterior
• may cause
teeth
irritation
soft
tissue
• acrylic portion can become
embedded in the soft tissue if
the palatal tissue hypertrophies
because of poor oral hygiene
TRANSPALATAL BAR
• more hygienic
• easy fabrication
• Allows teeth to move and tip
mesially
• failure to adequately
maintain space and remain
passive
Fabrication of transpalatal bar
1. fitting of bands on 1st permanent molars
2. removal of bands and taking impression
3. molar bands that were fitted are fitted to the maxillary cast by slight carving of plaster
4. arch wire contoured to close approximation of palatal surface
5. ends of wire are spot wel ded and then soldered to molar bands
(taken from Dr. Retrouvey’s private clinic)
Fabrication of Nance appliance
1. fitting of bands on 1st permanent molars
2. removal of bands and taking impression
3. molar bands that were fitted are fitted to the maxillary cast by slight carving of plaster
4. lingual arch is contoured to fit the inside of upper arch
- anterior portion of arch wire does not touch the lingual surfaces of the upper front teeth
- contoured against slope of the anterior portion of palate approximately 1 cm lingual to the lingual
surfaces of the central incisors
5. arch wire is spot welded to each molar band
6. a small acrylic button is cured on the most anterior portion of the arch wire
(taken from Dr. Retrouvey’s private clinic)
LINGUAL ARCH SPACE MAINTAINERS
Indications:
The lower lingual holding arch is indicated when there is bilateral loss of mandibular primary
teeth or loss of multiple mandibular primary teeth unilaterally. The permanent incisors must
be erupted.
A lingual holding arch can be used in the maxilla as long as the bite is not deep enough that the
lower incisors contact the wire on the lingual of the maxillary incisors.
http://en.wikipedia.org/wiki/Lingual_arch
Contraindications:
Permanent mandibular incisors not yet erupted.
A deep bite is a contraindication for upper lingual holding arches.
Advantages:
Prevents the loss of leeway space by maintaining the position of the molars. Also supports the
incisors and prevents them from moving lingually.
Disadvantages:
The first permanent molars or secondary primary molars are banded, and this may cause
decalcification of these teeth.
The permanent mandibular incisors must be erupted, otherwise they may erupt lingual to the
wire.
Fabrication:
(a laboratory processed appliance soldered to a molar band that requires two visits by the
patient)
1) Bands are adapted to the most posterior tooth remaining on the arch (first
permanent molar or second primary molar)
2) A pick up alginate impression is taken.
3) The appliance is fabricated in a laboratory. A 0.036” stainless steel wire is
soldered to the bands. This wire must be 1.5 mm away from the soft tissues for
gingival health. This wire should rest on the cingula of the incisors.
4) Cementation with appropriate cements (described earlier).
Removable Space Maintainers
Indications:
The removable space maintainers, or partial denture space maintainers, are useful when there
is bilateral premature loss of primary molars or unilateral loss of multiple primary teeth, and
the permanent incisors have not yet erupted. In this case, a lower lingual holding arch is
contraindicated due to the likelihood of the mandibular permanent incisors erupting lingual to
the wire.
Bijoor R, Kohli K. Contemporary space
New York State Dental Journal 2005 vol:71:32-5
maintenance
for
the
pediatric
patient.
Contraindications:
Removable space maintainers are avoided if possible because of the lack of compliance in
younger patients. They are frequently misplaced,
loshttp://www1.umn.edu/dental/courses/dent_5501/images/inter4.jpgt and broken.
Unilateral removable space maintainers should never be used due to their small size and the
danger of swallowing.
Advantages:
Maintains the leeway space via incorporation of false teeth.
Since there are false teeth incorporated into the appliance, occlusal function is restored.
Anterior esthetics can also be restored when there is premature loss of primary anterior teeth
in conjunction with premature loss of primary posterior teeth, even though between the
canines space loss is not a major concern.
Disadvantages:
Retention must be good for improved patient compliance, therefore there are usually several
clasps incorporated into the design which may complicate oral hygiene. These clasps, as well as
the acrylic, must be adjusted frequently due to the eruption and movement of permanent teeth.
TREATMENT PLANNING FOR SPACE MAINTAINERS
William Proffit. Contemporary orthodontics. 3rd edition. Mosby 2000: 421-423
REFERENCES
1. Lin YT, Lin WH, Lin YT. Immediate and six-month space changes after premature loss of a
primary maxillary first molar. JADA 2007 vol 138:362-8
2. Bijoor R, Kohli K. Contemporary space
New York State Dental Journal 2005 vol:71:32-5
maintenance
for
the
pediatric
patient.
3. Yilmaz Y, Kocogullari ME, Belduz N. Fixed Space Maintainers Combined with open-face Stainless
Steel Crowns. J Contemp Dent Pract 2006 May;(7)2:095-103.
4. WA, Brill. The distal shoe space maintainer: chairside fabrication and clinical performance.
Pediatric Dentistry 2002 vol. 24(6): 561-565
5. Gegenheimer R. Donly KJ. Distal shoe: a cost-effective maintainer for primary second molars.
Pediatric Dentistry 1992 Jul-Aug 14(4): 268-9
6. William Proffit. Contemporary orthodontics. 3rd edition. Mosby 2000: 421-423
7. Pinkham. Pediatric dentistry: infancy through adolescence. 4th edition. Elsevier Saunders 2005:
427-429
8. Sim, Joseph. Minor tooth movement in children. 2nd edition. Mosby 1977:385
9. William Proffit (1986). Contemporary Orthodontics. Toronto: The C.V Mosby Company. 313-317.