This observational study aims to investigate the relationship between periodontal morphology, oral hygiene habits, and non-carious cervical lesions (NCCLs) in adults aged 18-65 years. The main questions it aims to answer are:

Is there an association between periodontal soft tissue characteristics and the presence of NCCLs? Are oral hygiene habits and parafunctional behaviors associated with NCCLs?

Participants will:

Complete a structured questionnaire about oral hygiene habits and oral behaviors Undergo a clinical periodontal examination including assessment of plaque index, gingival index, probing depth, gingival recession, keratinized tissue width, gingival phenotype, and NCCL presence on the maxillary first premolar tooth

Periodontal morphology and oral hygiene behaviors may play an important role in the development of non-carious cervical lesions (NCCLs), which are characterized by the loss of dental hard tissue at the cervical region of the tooth without the presence of dental caries. NCCLs are considered multifactorial conditions associated with mechanical stress, toothbrushing habits, parafunctional behaviors, and periodontal soft tissue characteristics.

This cross-sectional observational study is designed to investigate the relationship between periodontal morphology, oral hygiene habits, and the presence of NCCLs in adults aged 18-65 years attending the Faculty of Dentistry of Necmettin Erbakan University. A total of 180 participants are planned to be included.

Clinical periodontal examination will be performed on the maxillary first premolar tooth. The evaluated parameters will include probing depth, gingival recession, clinical attachment level, keratinized tissue width, gingival phenotype, plaque index, gingival index, dentin hypersensitivity, and the presence of NCCLs. Tooth position and parafunctional habits associated with occlusal stress will also be recorded.

Participants will complete a structured questionnaire regarding demographic characteristics, oral hygiene practices, toothbrushing frequency and technique, toothbrush type, brushing force, and oral habits.

The primary objective of the study is to determine whether periodontal soft tissue characteristics and oral hygiene-related behaviors are associated with the presence of NCCLs. Statistical analyses will include descriptive statistics, group comparisons, and multivariable logistic regression analyses to identify factors independently associated with NCCLs.

Inclusion Criteria:

• Adults aged between 18 and 65 years
• Presence of the maxillary first premolar tooth in the oral cavity
• Presence of at least 20 natural teeth
• Periodontally stable individuals without generalized active periodontal destruction
• Systemically healthy individuals or individuals with controlled systemic diseases
• Individuals who voluntarily agree to participate and provide informed consent

Exclusion Criteria:

• Presence of extensive restoration, caries, endodontic treatment, cervical restoration, crown/bridge restoration, orthodontic brackets, or retainers on the maxillary first premolar tooth
• Missing posterior teeth or edentulous posterior segments
• Ongoing orthodontic treatment
• Severe bruxism or use of occlusal splints/night guards
• Gastroesophageal reflux disease or bulimia nervosa
• Frequent acidic beverage consumption
• Smoking ≥5 cigarettes per day
• Pregnancy or lactation
• Individuals unable to comply with the clinical examination procedures

Adult patients attending the Faculties of Dentistry at Necmettin Erbakan University and Bilecik Seyh Edebali University for routine dental examination or periodontal evaluation will be recruited for this observational study. Participants will be selected from individuals presenting to the university dental clinics during the study period. The study population consists of community-based dental patients undergoing routine clinical periodontal assessment and questionnaire-based oral health evaluation.