Multiband appliances belong to the group of fixed orthodontic appliances for the correction of malocclusions. Fixed therapy is usually preceded by treatment with removable appliances. Many orthodontic treatments are performed with fixed multiband appliances for a part of the therapy period. This affects a number of anomalies in tooth position, such as rotated positions, teeth that are offset overall, or root tilts. Even treatments in adulthood usually require a fixed appliance. Multiband appliances basically consist of:
- Brackets – These are bonded to the labial surfaces (outer tooth surfaces), or to the lingual surfaces (inner tooth surfaces) in the lingual technique. They are divided into base (sticks on the tooth) and stem, which carries the slot (slit, notch) for the archwire and wings for the ligatures. Brackets are available not only metal, but also ceramic.
- Bands – They are cemented on the molars (back molars). The archwire locks into a lock on the buccal (cheek) side of the band.
- Archwire – It is the element of the multiband appliance that actively affects the position of the teeth. The archwire runs through the bracket slots and is used in various thicknesses, degrees of elasticity, cross-sections and materials. Thin, highly elastic archwires are replaced by progressively thicker and more rigid archwires as treatment progresses.
- Ligatures – thin wires used to secure the archwire in the bracket.
- Alastics – colored rubber rings for fastening the archwire in the bracket.
In addition, if necessary, auxiliary elements such as:
- Elastics – elastics, clamped to the wings of the brackets, can run both in addition to the alastics intramaxillary (between teeth of one jaw) or clamped intermaxillary (between the upper and lower jaw) to influence the positional relationship of both jaws to each other and jaw growth. The therapeutic success of the elastics depends decisively on the cooperation of the patient. Ideally, the elastics are worn all day and are only unhooked during meals and for dental hygiene. Due to the gradual loss of elasticity, they are replaced daily.
- Pressure springs – for example, to open gaps.
Indications (areas of application)
In principle, any orthodontic treatment, regardless of whether it takes place with removable or fixed appliances, has the following therapeutic goals:
- Setting a neutral dentition (defined position of the upper and lower teeth to each other during chewing closure and chewing movements).
- Optimizing the function of the craniomandibular system (the masticatory system).
- Improvement of the aesthetics
In many cases, the therapy goal can only be achieved by combining removable appliances with multiband treatment. Here, the treatment with fixed appliances shortens the overall duration of orthodontic therapy on the one hand due to the all-day wearing time; on the other hand, not purely tilting, but physical tooth movements are only possible with a multiband appliance. It is also a prerequisite for most adult treatments. Therefore, indications for fixed treatment include:
- Physical tooth movements
- Rotations around the tooth axis
- Axis-fair setting of teeth by torque (torsion).
- Straightening of tilted molars – for example, the 12-year molars (the second posterior molars) after premature loss of the 6-year molars (the first posterior molars).
- Gap closure in adults
- Gap opening in adults
- Cover bite treatment
- Pronounced Spee curve (occlusal curve, running through the chewing contacts of the upper and lower teeth).
- Vertical growth pattern (growth tendency of the mandible tending to an open bite).
- Adult crossbite (the buccal cusps of the upper posterior teeth facing the cheek bite centrally into the occlusal relief of the lower posterior teeth instead of laterally past their buccal cusps)
- Buccal nonocclusion / scissor bite in adults (the mandibular posterior tooth bites completely past the buccal side of the maxillary posterior tooth)
- Forming the upper and lower dental arch.
- Among other things
Contraindications
- Poor oral hygiene
Before the procedure
In most cases, treatment with a fixed appliance is preceded by treatment with removable appliances. In a separate treatment session a few days before the insertion of the multiband appliance, rubber rings are inserted in the proximal spaces (interdental spaces) in front of and, if necessary, behind the first molars (posterior molars, six-year molars) to separate them, i.e. to loosen the tight contact points with the adjacent teeth before their banding.
The procedures
I. Edgewise technique
It is based on the original Angle method with edgewise arches and compatible brackets, in which defined bends are incorporated into the arches. The teeth react to these bends with controlled movements. II. Straight-wire technique
Developed by Andrews in the 1970s, this technique works with a straight wire. Here, the movement impulses come from the brackets individually defined for each tooth: Three-dimensional tooth movements can be initiated by bracket stems of different thicknesses (sitting on the bracket base) and different positioning of the bracket slot (slot through which the wire runs) to the bracket base (sticks to the tooth). Therefore, correct positioning of the bracket on each tooth is extremely important in this technique. III. Bioprogressive technique
The technique treats anterior and posterior teeth separately according to their eruption times. The treatment begins with the shaping of the anterior region by means of partial arches, while the posterior teeth are later included in the treatment, also by means of partial arches, after they have erupted. Only in a final treatment phase do the dental arches receive continuous wires for harmonization. The bioprogressive technique is used, for example, in:
- Cover bite
- Low anterior overbite
- Frontal slightly open bite
IV. Begg technique / light-wire technique
The technique combines a thin arch (English : light wire) of round cross-section with a special bracket that transmits tilting movements in mesiodistal and buccolingual direction (from front to back and outside to inside, respectively) to the teeth. First, the crowns of the teeth are moved to the desired position by tilting, then the roots are moved, thus aligning the teeth to the final position. Aids are used for tooth movement. A disadvantage of this technique is increased horizontal bone resorption and root resorption (degradation of root cementum and dentin in the area of one or more tooth roots). V. Lingual technique
The lingual technique is characterized by a great aesthetic advantage, since the brackets are fixed lingually (on the tongue side of the teeth). The somewhat restricted freedom of movement due to the brackets can have a disadvantageous effect on the tongue motor function and thus on speech. The technique is not suitable for dysgnathia (jaw and tooth malocclusions) where no further bite opening is allowed, such as in cases of slight vertical anterior overbite or already open bite.
The treatment procedure
Immediately before insertion of the multiband appliance, professional tooth cleaning (PZR) is recommended. The insertion of the bands and brackets itself is as follows:
- Removal of the rubber rings in the approximal spaces.
- Adjustment and cementation of the bands on the first molars
- Adhesive attachment of the brackets to the labial surfaces (surfaces facing the lip) of the teeth: for this purpose, the enamel surface is chemically roughened and coated with thin flowing acrylic, which forms a micromechanical bond with both the pre-treated enamel surface and the base of the bracket.
- Insertion of the first archwire into the bracket slots.
- Fastening the archwire using wire ligatures or alastics clamped to the bracket wings
- Bracket environment sealing for longer-term protection of the enamel.
In the course of further multiband treatment, numerous control appointments must be perceived, at which the replacement of the arches: If highly elastic thin arches are incorporated at the beginning, increasingly more rigid and stronger arches are used as the treatment progresses. Treatment with a multiband appliance proceeds in five phases:
- Leveling phase – dental arch shaping in the horizontal and vertical as well as derotations (position corrections of teeth by turning them out).
- Guidance phase – movement of individual teeth in sagittal and transverse direction (from front to back and transverse to it) so as bite opening or closing.
- Contraction phase – eliminating gaps and sagittal steps.
- Adjustment phase – harmonization of dental arches and small residual corrections.
- Retention phase – holding the treatment result.
After the procedure
After the removal of the bands and brackets, the retention phase continues with removable appliances and / or adhesively bonded retainers, which are attached to the lingual side (tongue side) of the upper and lower incisors.
