The impact of tooth brushing on enamel affected by Molar Incisor Hypomineralisation (MIH)

First permanent molars affected by Molar Incisor Hypo mineralisation (MIH) are susceptible to post-eruptive enamel breakdown. One factor affecting this might be toothbrush abrasion. The main aim of this study is to examine whether tooth brushing will increase enamel loss in MIH teeth or not. Differences in tooth wear progression in MIH affected enamel vs unaffected enamel were measured using an in vitro abrasion/erosion model with different toothpastes. 14 MIH molar teeth and 14 control premolar teeth were collected, and sectioned so that each enamel sample consisted of a complete cusp with its corresponding buccal/lingual wall or mesial/distal sections. Each sample was embedded in epoxy resin and then mounted in a custom-made apparatus, which held the samples during brushing with four Oral-B Professional care Trizone 2000 electric toothbrushes. Abrasion was done using the 3:1 relation slurry of the artificial saliva along with the toothpaste after one hour of immersion in the artificial saliva. This is followed by 10-15 minutes of incubation in 0.3% citric acid. Enamel loss was quantified using Optical Coherence Tomography (OCT). Teeth were scanned under Scanning electron Microscopy (SEM) to evaluate differences between eroded enamel surfaces vs the uneroded surfaces. OCT scans showed that the MIH lesions with brown discoloration had more evidence of enamel loss compared to control. MIH teeth with white/yellow discoloration did not show significant wear compared to dark/brown discolouration. SEM scans images showed significant difference between enamel in sound teeth and enamel affected by MIH. It has also displayed the differences between various MIH types, and the effect of different toothpastes on the eroded enamel surface. In conclusion, MIH teeth with brown discolouration were more prone to wear than white/creamy discolouration.