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Lingual appliances (Figure 1.7):

 First developed in the 1970s in the USA.

 The brackets are bonded onto the palatal/lingual surface of the upper and lower arches.

 Lingual appliances use preadjusted ribbonwise brackets, which are thicker vertically than horizontally.

 All brackets and archwires are custom made to reduce speech problems and tongue irritation and to help improve finishing.

 Custom‐made brackets are good as they can be rebonded directly back on if they debond during treatment; however, if a bracket is lost, new ones have to be specially ordered.

 Brackets come in a jig and are all bonded together at once (indirect bonding). It is important to keep the bracket in the jig, because there can be undesired tooth movement if it comes out or is bonded directly to the tooth without a jig.

 Lingual appliances can also come in a self‐ligating form.

Advantages:

 Good aesthetics.

 Decalcification less likely to occur with lingual appliances compared to labial appliances; however, if present it will not be visible.

 Upper anterior brackets can act as a bite plane, which is good for treating overbites (flat anterior bite plane or FABP).

Disadvantages:

 Can affect patient’s speech.

 Much more ulceration can appear.

 Discomfort to patient’s tongue.

 Clinically demanding on clinicians.

 Inter‐bracket span is reduced.

 Increased chairside time.

 Finishing and detailing are difficult to achieve due to the reduced inter‐bracket span, and archwire bending can be made difficult.

 Indirect bonding of brackets or debonding of brackets can result in poor positioning if not bonded back in the correct position.

 Increased cost.

 Longer treatment time.

Figure 1.7 Typhodont showing Harmony lingual appliance.