Orthodontic bracket etchant minimising enamel damage and demineralization


Adhesive systems for orthodontic brackets, or braces, are required to have bond strength sufficient to prevent failure but not threaten enamel damage upon removal.  Tooth damage can result when the bracket and/or residual adhesive is physically removed from the tooth surface.  Enamel demineralization is also common problem during tooth realignment using braces.  King’s researchers have developed a novel bracket etchant composition that combines satisfactory bond strength using known bonding adhesives, non-damaging removal and remineralization activity to avoid mineral loss.

The Problem

Orthodontic brackets, used to realign teeth and to correct a person’s bite, are attached to the patient’s teeth for long periods.  Brackets are linked by an arch wire, which puts pressure on the brackets and teeth in order to reposition the teeth.

In order to transfer the pressure from the arch wire to the tooth, the orthodontic bracket must be securely attached to each tooth; typically to the buccal enamel using a bonding or adhesive material.  Once the orthodontic brackets are no longer required (when teeth have been moved to the desired positions) the brackets need to be removed from the teeth.

Bonding agents for the orthodontic brackets are generally required to have a bond strength sufficient to preclude bond failure, but not so strong as to threaten enamel damage upon removal.  Enamel damage can be caused when the bracket is physically removed from the tooth, from removal of any residual bonding agent (adhesive) from the tooth after removal, or a combination of the two.  Enamel demineralization is also a common occurrence during a course of treatment with orthodontic brackerts.

Even with no or minimal enamel damage, the need to remove residual adhesive and polish the enamel surfaces of teeth post-treatment adds to chair time.


The Solution  

King’s researchers have developed an orthodontic bracket etchant composition that allows satisfactory bond strength of the orthodontic bracket to the tooth using known bonding adhesives. The innovation provides an etchant composition comprising calcium phosphate and an aqueous solution of an etchant acid.

The etchant composition may include calcium phosphate in several different crystalline forms together with an aqueous solution of the etchant acid, which is frequently phosphoric acid.


The bracket etchant composition:

•       minimises or eliminates the risk of enamel damage to the tooth on removal;

•       reduces the amount of adhesive remaining on the tooth;

•       minimises enamel demineralization around bracket.



We are seeking a commercialisation partner wishing to take an option / licence over the technology. Exclusivity is available for a suitable partner.


IP Status

Pending as an International PCT patent application, taking priority from an earlier GB filing. The Sole Applicant is King’s College London, UK. (Published as WO2018/011338 A1.  Priority date: 13 July 2016). 




Figure: SEM images of the enamel surfaces of teeth following (a) etching with conventional 37% phosphoric acid solution, orthodontic bracket adhesion and subsequent debonding (left image); or (b) etching with a bracket etchant composition including crystalline calcium phosphate and phosphoric acid, orthodontic bracket adhesion and subsequent debonding (right image). Note residual adhesive and tooth damage in (a) and clean tooth surface in (b).


Patent Information:
For Information, Contact:
Ceri Mathews
IP & Licensing Manager
King's College London
Sanjukta Deb
Van Thompson
Ali Ibrahim