Brackets: the built-in prescription works only if placement is accurate

The bracket carries information that the wire transmits to the tooth: angulation, inclination and base thickness are designed to bring each element into a predetermined position.

This works on one condition that tends to be assumed: that the bracket is bonded in the exact position for which it was designed. An error of half a millimetre in height produces unintended extrusion or intrusion.

Height error is the most frequent and the hardest to recognise afterwards, because the outcome looks like a prescription problem when it is a bonding problem.

The most widespread prescriptions are Roth and MBT, differing chiefly in torque values on the incisors and angulation of the canines. MBT prescribes higher torque on upper incisors and values intended for sliding mechanics.

Neither is superior in absolute terms: they are coherent systems, and the problem arises when brackets of different prescriptions are mixed in the same arch because that is what was in the drawer.

Slot dimension determines how much play exists between wire and bracket. A 0.022-inch slot accepts larger wires and permits greater forces in the final phases, but leaves considerable play with thin wires.

An 0.018 slot expresses torque earlier, because play is smaller, but limits the maximum usable wire dimension. The choice depends on the preferred mechanics, not on the superiority of either.

Ceramic brackets answer the aesthetic request and have two known limitations. Friction against the wire exceeds that of metal, which slows sliding during space closure.

The second limitation is more serious: ceramic is harder than enamel, and a ceramic bracket contacting the antagonist wears it. In the lower anterior segment with a deep bite, this is a real contraindication.

Debonding also requires care, because ceramic has high bond strength and can take enamel with it unless the correct technique with dedicated pliers is used.

Self-ligating brackets replace the elastic ligature with a clip. The documented advantage is reduced friction and reduced chair time at every visit.

The reduction in overall treatment duration, which is the principal commercial claim, is less supported by systematic reviews than manufacturers' communication suggests.

In summary: the prescription only works if bonding is precise, prescriptions are not mixed, ceramic brackets are contraindicated against a contacting antagonist, and self-ligating brackets save chair time rather than months of treatment.