**5. Rebonding of ceramic brackets**

Although some major orthodontic supply companies explicitly state in their instruction sheets that their ceramic brackets are for single use only, several laboratory studies suggested various techniques for the reuse, i.e., the rebonding, of ceramic brackets [40–44]. For reuse, the bracket has to be intact in the first place.

It has been pointed out that the appropriate term is "reuse" or "recondition" instead of "recycle," since the term "recycled" implies the manufacturing of new brackets from the raw material of the original, failed brackets [12]. Nevertheless, the literature usually refers to these brackets as "recycled."

An in vitro study [43], carried out in 2016, investigated the "recycling" of polycrystalline ceramic brackets with a microcrystalline base via the following three methods: first is the erbium-doped yttrium aluminum garnet (Er:YAG) laser, and the other two are traditional methods, i.e., flaming and sandblasting. Sandblasting (50 μm Al<sup>2</sup> O3 particles) damaged the delicate bracket base structure and demonstrated significantly less bond strength than new brackets. The flaming procedure yielded a bond strength that was similar to that of new ceramic brackets. However, flaming affected the esthetics of these brackets, i.e., these brackets ended up faded and dark. Er:YAG lasers completely removed the adhesive remnants from the ceramic bracket bases without damaging the base structure. Furthermore, the shear bond strength of Er:YAG laser "recycled" brackets was similar to that of new brackets. It was pointed out that the laser method may be preferred over other "recycling" methods.

Yassaei et al. [44] also concluded that the Er:YAG laser presents an efficient way for "recycling" ceramic brackets. These researchers used polycrystalline ceramic brackets with a dovetailed base in their in vitro study.
