Multiband appliances
The Begg technique is an orthodontic technique with fixed appliances that uses special wires and brackets.The special types of bracket for this technique are called Begg brackets.Tipping as well as single-point contact can be achieved with these brackets. Tooth movements are enforced with light elastics.The archwire is fixed in the slots with lock pins.
The treatment takes place in three stages:
- Stage 7;The occlusion is opened, and the anterior teeth are placed in the edge-to-edge position; at the same time, crowding and tooth rotations are eliminated.
- Stage 2; If extraction therapy has taken place, the extraction spaces are closed.
- Stage 3;The tipped incisors and posterior teeth are aligned. Finally, fine adjustment of the teeth is carried out; the appliance is then removed.
Light wire technique denotes the use of fixed orthodontic appliances in which the outer arch of round highly elastic wire (0.3 to 0.45 mm) is fitted into the brackets on all the teeth. The force effect is minimized by guiding the wire into loops bent inward between the brackets. The arms of the bent-in loops run parallel at the same height before placement in the brackets.The basic shape of the arch corresponds to the intended ideal dental arch form. The archwire is inserted into the brackets under tension and fixed in place. It is anchored with horizontal tubes to the molars, which are also banded.
After fixation, the wire is under highly varied pre-tension for each tooth, depending on the defective position of the tooth concerned. In extreme positional anomalies, several archwires have to be individually shaped and inserted in successive treatment steps.
The Ricketts technique (bioprogressive technique) uses very thin and elastic wires that are gradually applied step by step to the banded teeth. The teeth are controlled with loop arches as far as possible and moved without frictional resistance.
The twin arch technique refers to the working of two archwires made of 0.25-mm wire that are guided into special brackets and tubes. The thin,
spring hard wires exert only very weak spring forces. In addition, pressure and tension springs are used to tighten the wires.
The bracket adhesive technique refers to the multiband technique in which the orthodontic fixing components (brackets and tubes) are no longer fixed via bands but are directly bonded to the enamel pretreated with acid. An epoxy resin adhesive is used to bond brackets made of acrylic, porcelain, or metal to the enamel surface that has been conditioned with 40% phosphoric acid (H3PO4).
Direct bracket fixation requires no approximal separation of the teeth being banded. Only a few residual spaces remain after band removal, incompletely erupted teeth can be bonded, and better prevention of caries and gingivitis is ensured. Caries lesions are possible with the bracket adhesive technique in the marginal area around the brackets and in the interdental area, so intensive oral hygiene is required, with support from fluoridation measures.
Bonded brackets can be worked more quickly and more simply than bands. All individual tooth forms can be covered by a few standard bracket types, making extensive, costly band supports unnecessary. Vertical and horizontal placement of the brackets is far more difficult with the adhesive technique. Bracket removal and subsequent enamel polishing are labor-intensive, and enamel chips or adhesive strands can appear in the enamel mantle.
High bond strength requires the acrylic to penetrate into the exposed microporosities of the conditioned enamel.The etched enamel surface must therefore have the following structure:
- Minimal, irreversible loss of height
- Rough, retentive microrelief with intraprismatic spaces
- Considerable enlargement of surface area for better wettability of the enamel
After etching, the dissolved residues of calcium crystals are removed from the enamel surface to achieve tight interlinking between the adhesive and the enamel.
Figures 10-94 to 10-99 illustrate various considerations of multiband appliances.