The following clinical periodontal parameters will be assessed at 6 sites of each tooth (mesio-buccal, buccal, disto-buccal, mesio-lingual, lingual and disto-lingual): (i) probing pocket depth (PPD): it will be measured from the gingival margin to the bottom of the pocket; (ii) gingival recession (GR): it will be measured from the enamelcement junction to the bottom of the pocket; (iii) clinical attachment level (CAL): it will be measured as PPD + GR (GR will be equal to 0 whenever the cementenamel junction is covered); (iv) bleeding on probing (BOP): it will be evaluated dichotomously: the presence of the bleeding will be considered positive when occurring within 30 seconds from the insertion of the probe for probing depth; (v) Plaque index (PI): it will be evaluated dichotomously. BOP, PPD, CAL and GR will be measured at six sites per tooth (mesio-buccal, buccal, disto-buccal, disto-lingual, lingual and mesio-lingual). All probing measurements will be performed using an automated periodontal probe.