Page 114 - REMOVABLE ORTHODONTIC APPLIANCES

106 Removable Orthodontic Appliances
During a complex treatment de-rotation will control upper mid-line spaces (diastemas),
usually be carried out early so that the fixed fraenectomy has been popular. Fraenectomy
appliance itself will often retain the corrected before orthodontic treatment has been shown
rotations for a year or more before a removable to have little effect but may be useful following
retainer is fitted. This may help to reduce any space closure with fixed appliances. Gingival
post-treatment relapse. When the correction of surgery can also be useful to improve the
rotation is the main tooth movement the treat- appearance by reshaping the gingival contour.
ment time is likely to be shorter and relapse is Tissue compressed in the mid-line is a potent
much more likely. factor in the re-opening of mid-line spaces and
A number of techniques have been used to in such cases it is wise to be fairly radical,
stabilize rotations after fixed appliance therapy. removing the fraenum, reshaping the gingivae
A removable 'U' loop retainer is not very effec- and perhaps sectioning the transeptal fibres.
tive at maintaining rotations after correction by Even after this procedure other forms of reten-
fixed appliances. Even a fitted labial bow with tion will be required.
bends mesial and distal to the rotated tooth is A disadvantage of fixed retainers is that the
not effective in controlling a rotation and the ultimate responsibility for their care rests with
most satisfactory design is a labial bow with an the practitioner and if many patients have such
acrylic cover which engages firmly on the labial retainers this may become onerous. A remov-
surface of the teeth. An alternative is to use a able retainer is more fairly the patient's respon-
vacuum-formed semi-rigid splint of clear plastic. sibility, only requiring professional assistance
This is more effective than a conventional labial in the event of loss or damage. This does not
wire on a retainer because it provides intimate have the same degree of urgency as a broken or
contact with the whole crown of the tooth. The loose bonded retainer.
fact that the occlusal surfaces of the teeth are Retention is important. The more experi-
covered represents a disadvantage because it enced the orthodontist the more cautious he or
prevents the 'settling in' of the upper and lower she is likely to be about retention. Few patients
posterior teeth when this is required. Each case complain about retainer wear (fixed or remov-
must be judged on its merits. The priority during able) but almost all are disappointed by
the early months must be the maintenance of relapse, sometimes when only very small tooth
any corrected rotations. Once confidence in the movements are involved. At the outset of a
stability of this aspect is gained a vacuum- course of orthodontic treatment these factors
formed retainer may be discarded in favour of a should be explained to the patient who should
'U' loop retainer. Surgery in the form of perici- also be warned that a small degree of relapse
sion can help to stabilize treated rotations, but if must be expected in many cases despite the
it is required for more than one or two teeth it most careful postoperative care.
can become a traumatic procedure, especially
for a young patient.
Spaces which have been closed pose special References
problems for retention. The stability of extrac-
Little, R.M., Reidel, R.A., Artun, J. (1988) An evaluation
tion site closure is enhanced when the roots are of changes in mandibular anterior alignment from 10 to
parallel and the upper and lower posterior 20 years post-retention. American Journal of Ortho-
teeth have good intercuspation at the end of dontics. 93: 423-428
treatment. The upper mid-line space presents
the greatest challenge. Even vacuum-formed
retainers will not hold these spaces closed with- Further reading
out other forms of retention. Two other tech-
niques are available to aid the retention of Otuyemi. P.. Jones. S. (1995) Long term evaluation of
rotations and closed spaces - surgery and acid treated Class II division I malocclusions utilising the
etched bonded retaining wires. In attempting to PAR index. British Journal of Orthodontics, 22:171-178