*2.3. Sampling*

The samples were MIM teeth and the non-MIM teeth were the controls. The MIM samples included four permanent first molars and maxillary central incisors as one sample, and the non-MIM teeth including the maxillary left premolars and mandibular right premolars as one sample.

The oral microbiome was obtained from five habitats around the teeth in the two groups. The perio group included <sup>1</sup> a supragingival plaque, <sup>2</sup> subgingival plaque, and <sup>3</sup> an apical abscess, and the endo group included <sup>4</sup> a coronal pulp chamber and <sup>5</sup> a root canal (Figure 4). The perio samples were collected before the extractions, and the endo samples were collected after the extractions. All samples are listed in Table 1. The sample identification (ID) numbers refer to the two-digit FDI notations.

• **Perio group**

