Download the effect of intermaxillary elastics in orthodontic therapy

ORIGINAL
ARTICLES
THE EFFECT OF INTERMAXILLARY ELASTICS
IN ORTHODONTIC THERAPY
Cristina D. Bratu , Camelia Fleser , Florica Glavan
REZUMAT
Elasticele ortodontice sunt utilizate în toate tipurile de anomalii, Clasa I, Clasa a II-a [i Clasa a III-a, [i în ocluzii deschise, având meritul de a suplimenta
deplasarea mandibulei [i a nu necesita activ\ri repetate din partea ortodontului. Ele realizeaz\ deplas\ri orizontale, verticale, transversale, distaliz\ri,
mezializ\ri ale mandibulei, extruzii dentare, închideri de spa]ii, corectarea liniei mediane, a rela]iei intercanine [i în\l]area ocluziei. Lucrarea de fa]\ î[i propune
prezentarea câtorva aplica]ii ale elasticelor în optimizarea ortodontic\ în anomaliile de Clasa a II-a Angle [i ocluzia deschis\ fronto-bilateral\.
Cuvinte cheie: for]e ortodontice, elastice intermaxilare clasa a II-a, anomalie dentomaxilar\ clasa II/1, ocluzie deschis\ fronto-bilateral\.
ABSTRACT
Orthodontic elastics are used in all kinds of malocclusions: Class I, Class II, Class III and open bite. Their aim is to increase the movement of the mandible,
without the need of multipe activations by the orthodontist. Their effects are: horizontal, vertical, transersal movements, mandible distalizing and mesializing,
dental extrusion, space closing, midline shift and intercanine relation correction, opening the bite. Our study will pesent some of the clinical applications of
orthodontic elastics in Class II and fronto-bilateral openbite malocclusions.
Key Words: intermaxillary Class II elastics, Class II/1 malocclusion, open bite, orthodontic forces.
INTRODUCTION
Orthodontic treatment represents a major
investment in the future dental health and appearance.1
Teeth move as a reaction to forces applied to them.2
In many cases, we use other teeth in the same jaw to
give them resistance or anchorage, needed to provide
the required forces.3 Most often, usually when several
teeth need to move in the same direction, it is not
possible to produce the change required using
appliances anchored in just one jaw. During some
phases of orthodontic treatment, elastics or rubber
bands are used to move teeth or jaws, or sometimes
both.4,5 By carefull treatment planning and controlling
the strength, direction and duration of forces, we aim
to keep our use of elastics and headgear to a minimum.
Department of Pediatric Dentistry and Orthodontics, Faculty of Dentistry,
Victor Babes University of Medicine and Pharmacy Timisoara
Correspondence to:
Dr.Dana Cristina Bratu, Department of Pediatric Dentistry and
Orthodontics, Revolutiei Blvd. 9, Tel. +40-256-491943
Email: [email protected]
Received for publication: Nov. 05, 2003. Revised: Jul. 19, 2004.
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TMJ 2004, Vol. 54, No.4
In some cases a good treatment outcome will be
impossible without a lot of work using elastics,
headgear or both.
The first known elastic was used by the Inca and
Maya civilizations and was extracted from Hevea trees.2
Later, in 1728, Pierre Fouchard proposed to close
anterior diastema with silk ligature.1 From this moment
on the history of using elastics in orthodontics abounds
in writers, culminating with Ricketts in 1970, which
applyed the Bioprogressive segmented light square wire
technique advising the closing elastics conduct in open
bite cases. 2 Roth recommends short Class II
intermaxillary elastics to help leveling the curve of Spee
in association with extraoral forces. Langlade has the
merit of developing clinical applications of elastic forces
in different situations, proposing rules of biomechanics .6
MATERIAL AND METHOD
Intermaxillary Class II elastics are placed on the
anterior maxilla and posterior mandible.6 We used
intraoral elastics produced by GAC International Inc.
NY USA, made from latex and available in different
sizes and shapes. They are available in “light”,
“medium”, “heavy” and “super heavy” types, each of
them performig a different force on the teeth. Each
bag of GAC elastics contains a bright white placer for
the patient.
This study was conducted on a number of 20
patients with Class II/1 and fronto-bilateral open bite
anomalies. Application of the elastics was different,
depending on the clinical situation. We used classic,
triangular and rectangular elastics.
Figure 11: Orthodontic elastics in different clinical situations
Elastics were inserted at the maxillary arch, anterior
from a canine bracket hook, a Class II utility arch, a
Kobayashi wire ligature or a continuous archwire with
anterior loop.
At the mandibular arch, elastics were inserted
posterior, labial or lingual: distal to a molar tube,
different teeth (M2, M1, Pm 2, Pm 1), a Kobayashi wire
ligature, a hook or a loop.
Effect of Class II elastics is the maxillary distalizing,
mandibular advancement and closing the bite.
With a mouth open of 10 mm during speech,
the force varies with different angulation of the Class
II elastic and has different effects upon the maxillary
and mandibular arches.6
In the maxillary arch, the vertical component of
extrusion is smaller than the horizontal component
of distalizing.
In the mandibular arch, the horizontal
component of advancement is smaller than the vertical
force of extrusion. In different clinical situations, the
patients were instructed to wear the elastics during night
and day. During daytime,6 intermaxillary elastics have
a vertical component of extrusion that is much more
significant than the horizontal component, their effect
being increased by the functional movements
(mastication, phonation). According to the
orthodontist’s prescription, they must be changed
1-2-3 times/day. During the night, 6 intermaxillary
elastics have an equivalent vertical and horizontal
component.
Class II elastic indications:
Class II elastics may be used for main and
secondary objectives in the following clinical situations:
skeletal and/or dental Class II malocclusions,
anchorage reinforcement, backward movement of the
upper incisors, mandibular arch advancement, buccal
tipping of retruded lower incisors, bite opening (class
II/2), midline deviation correction.6
They are recommended only after the correction
of overbite and segmentation of the maxillary archwire.
The class II elastics have different effects:6
a. effects upon the maxillary arch:upper incisors
are more vertical, extrusion and downward movement
of anterior occlusal plane, backward movement of the
upper arch, dental distalization.
b. effects upon the mandibular arch: buccal
tipping of lower incisors, forward movement of the
entire mandibular arch, extrusion of the lower first
molars.
c. effects on the facial patterns: forward
movement of the chin, forward movement of the
mandible with a posterior rotation; The lower facial
height will depend on the wearing time and the amount
of elastic force used.
d. effects on the occlusal plane:lowering of the
anterior occlusal plane, sagital correction of the Class
II relationship.
RESULTS
Figure 2: Biomechanic influence of elastics in Class II anomalies
Representative clinical cases
Case 1
Patient S.A. presented a Class II/1 malocclusion.
After retraction of the frontal group and obtaining a
functional overjet, the patient wears Class II elastics.
Effects of Class II elastics: mandible distalizing,
mesial movement of the mandible, lateral extrusion.
Cristina D. Bratu et al.
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Case 4
Patient A.B. presented a fronto-bilateral open
bite. After solving the lateral occlusal problems, we
applied frontal rectangular elastics in order to close
the bite.
Figure 3. Clinical case and representation of Class II elastics
Case 2
Patient A.M. presented narrow upper arch and
and bilateral canine ectopy. After alignment of the
canines, triangular elastics were applied.
Figure 6. Rectangular elastics to close the open bite
Frontal elastics in rectangular shape produce:7
transversal changes, upper and lower anterior group
extrusion, mandibular rotation.
DISCUSSIONS
Figure 4. Clinical case with triangular elastics
Triangular elastics produce canine extrusion,
occlusal and vertical stability of the canine, and the
presence of two oblic forces, with the movement of
the tooth along the bisector line direction.
Case 3
Patient F.M. presented with a Class II/1
malocclusion. In the final stage, we applied rectangular
intermaxillary elastics for occlusal setlling.
Some clinical problems may appear even with
careful clinical observation: 6 excessive or insufficient
wearing, periodontal problems of the lower teeth,
unwanted space opening or closing, loss of anchorage,
unwanted rotation or extrusion, abnormal tipping,
temporomandibular disorders, incorrect placement of
the elastics by the patient, the elastic properties may
decrease or be lost.
After 2 hours from the insertion of elastics6 in
the oral cavity, the elastic properties decrease with 30%,
and after 3 hours, with 40%. After 1 month after
insertion, elasticity was 50% off.10
After comparing the effects of Class II elastics
and the fixed functional appliances such as Herbst,
other authors 8,9,10 have found more pronounced
vertical changes after elastic treatment.
The disadvantages of intermaxillary elastics are
minimal and the results are optimal, with the condition
of a carefull diagnosis and treatment planning.
CONCLUSIONS
Figure 5. Rectangular elastics
Effects of lateral rectangular elastics: distalizing of
the upper arch, advancement of the lower arch,
horizontal and vertical equal forces which rearrange
the oclussion in the finishing stage.
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Our conclusion is that it would be advisable to
use intermaxillary elastics in the finishing stage of
orthodontic treatment, in order to obtain an optimal
occlusion and a long time stability of the orthodontic
results.
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