The goal of this observational study is to investigate the ability of Periodontists, Clinicians with Expertise in Periodontics and General Dental Practitioners to diagnose periodontitis using the 2017 AAP / EFP World Workshop classification of periodontal diseases.

The purpose of this study is to conduct a online survey in order to:

1. investigate Italian dentists' knowledge on the new classification of periodontal diseases.
2. evaluate the reliability of the diagnosis between different examiners in classifying periodontitis;
3. evaluate the accuracy of the use of grading in the diagnosis of periodontitis;
4. evaluate diagnostic accuracy of staging application in classifying periodontitis.

Four well-documentated clincial cases will be presented to Italian dentists (Periodontists, Clinicians with Expertise in Periodontics and General Dental Practitioners) through online survey to obtain a Clinical application of the 2018 classification of periodontal diseases Each participant will be asked to diagnose periodontitis using staging and grading for each clinical case.

Each periodontal case will be documentated according a previous study (Marini et al. 2022) specifing:

Age; Systemic diseases (presence/absence); Cigarette consumption ( <10 cig/day or >10cig/day); Tooth mobility (presence/absence) Tooth migration (presence/absence) Number of tooth loss due periodontitis (0; <4; > 5) Gingival bleeding (presence/absence) Familiarity for periodontitis

Each periodontal case will be presented showing:

Intra-oral photographs; Full-mouth periapical radiographs; Periodontal chart

Inclusion Criteria:

Periodontists, Clinicians With Expertise in Periodontics General Dental Practitioners

Periodontists, Clinicians With Expertise in Periodontics General Dental Practitioners

all IPD that underlie results in a publication

PD and any additional supporting information will become available when summary data are published.

according to journal policy