The goal of this observational study is to evaluate and compare a 3D intraoral scanner-based, computer-assisted approach for assessing dental biofilm/plaque accumulation on natural teeth and restorative surfaces with a conventional clinical plaque index (Turesky modified Quigley-Hein Plaque Index, TMQHPI) in systemically healthy adults. The main questions it aims to answer are:

• How well does the plaque-covered surface measurement derived from 3D intraoral scanner data agree with TMQHPI scores after plaque disclosure?
• How sensitively do the two methods detect changes in plaque levels after supervised toothbrushing?
• Do plaque accumulation patterns differ between natural tooth surfaces and restorative materials (direct composite restorations and indirect ceramic veneers), and where are plaque-retentive areas most frequently located?

Participants (≥18 years) will receive routine professional mechanical plaque removal as part of standard clinical care. They will then be asked to avoid mechanical and/or chemical plaque control for 4 days. At the follow-up visit, participants will undergo:

1. An intraoral scan and standardized photographs of the full dental arch,
2. Plaque disclosure followed by repeat scanning/photography and TMQHPI scoring by a periodontist,
3. Supervised toothbrushing using the modified Bass technique for 2 minutes, followed by a final scan and photographs. Digital models will be used to quantify plaque-covered surface measures and to generate 3D maps of plaque-retentive areas.

This is an observational, parallel-group study conducted at the Trakya University Faculty of Dentistry, Department of Periodontology, designed to compare a three-dimensional (3D) intraoral scanner (IOS)-based, computer-assisted approach for mapping and quantifying dental biofilm on tooth and restoration surfaces with a conventional clinical plaque scoring approach used in routine practice.  

Participants will be recruited from individuals attending the periodontology clinic who receive routine non-surgical periodontal care, including professional mechanical plaque removal (PMPR) and a standard motivational oral-hygiene session as part of usual clinical management. Following PMPR at the initial visit, eligible and consenting participants will be asked to refrain from mechanical and/or chemical plaque-control procedures for four days while maintaining their usual diet, to allow development of a mature dental biofilm for standardized assessment.  

Participants will be allocated into three groups based on the presence and type of maxillary anterior vestibular surface condition:

1. Natural tooth surfaces without restorations,
2. Direct composite restorations, or
3. Indirect ceramic veneer restorations. All groups will undergo the same standardized assessment workflow on day four. 

On day 4, whole-arch intraoral scans will be obtained using the TRIOS 3 IOS® (3Shape, Copenhagen, Denmark) following a standardized scanning strategy to capture 3D models of the dental arches (with emphasis on vestibular surfaces) and to enable digital archiving and subsequent analysis. The TRIOS 3® is a non-invasive optical device that generates a 3D surface model by processing sequential images into a point cloud and triangulated mesh; scanning does not require local anesthesia and does not involve ionizing radiation. Standardized intraoral photographs of vestibular surfaces will also be recorded at each stage for documentation and cross-referencing.  

The assessment visit includes three sequential stages:

1. Baseline IOS scanning and standardized photographs after the 4-day plaque accumulation period;
2. Application of a plaque-disclosing procedure as used in routine care, followed by repeat IOS scanning/photographs and conventional clinical plaque scoring by a calibrated periodontist; and
3. A supervised 2-minute toothbrushing session using the modified Bass technique with a manual toothbrush and fluoride toothpaste, followed by final IOS scanning and photographs to document post-brushing changes. If residual disclosed plaque remains after supervised brushing, it will be removed professionally (e.g., with brush and floss) before the participant returns to their usual oral-hygiene routine, and the study procedures will end at that visit.  

The IOS-derived 3D datasets will be used to compute quantitative plaque-related measures from the digital models and to generate 3D visual maps highlighting areas of plaque retention across the dental arch. These digital outputs will be compared with the conventional clinical plaque scoring approach to evaluate concordance and the ability to capture change after supervised brushing, and to explore potential differences in plaque accumulation patterns between natural tooth surfaces and restorative material surfaces.  

A total sample of 45 participants (approximately equally distributed across the three groups) is planned, based on an a priori power calculation with allowance for potential loss. Overall study conduct includes recruitment and assessments, followed by data organization and statistical analyses within the planned study period.

Inclusion Criteria:

• 18 years or older. 
• Able and willing to provide written informed consent. 
• Generally healthy and not using regular systemic medications. 
• Have at least 6 teeth in each quadrant of the mouth. 
• Have low plaque levels at baseline (plaque index <10%). 
• Do not have periodontal pockets deeper than 4 mm. 
• In the upper front teeth (maxillary anterior) on the outer (vestibular) surfaces, participants must fit one of these predefined surface types: Natural tooth surface (no restoration ), direct composite restoration, or Indirect ceramic veneer restoration. 
• No cavitated tooth decay on the surfaces to be assessed and no obvious surface defects that would clearly increase plaque retention.

Exclusion Criteria:

• Diagnosis of gingivitis or periodontitis. 
• Regular use of mouthwash as part of daily oral hygiene. 
• Use of antibiotics within the last 6 months. 
• Smoking. 
• Pregnant or breastfeeding. 
• Presence of dental implants or removable dentures. 
• Any systemic disease or medical treatment that could affect oral health or healing (examples include diabetes, cancer, disorders affecting bone metabolism, immunosuppressive therapy, chemotherapy, radiotherapy, or other conditions/medications affecting wound healing). 
• Having a pacemaker or an implantable defibrillator. 
• History of allergy or intolerance to study-related materials (e.g., ingredients of the plaque-disclosing agent or the lip/cheek retractor material). 
• Defective fillings/restorations on the assessed surfaces that could increase plaque retention. 
• Malocclusion or spacing between teeth (diastema). 
• Gum recession affecting more than one-third of the root length. 
• Wearing fixed orthodontic appliances (braces). 
• Any physical, mental, or psychiatric condition that could interfere with understanding the study or completing the procedures

Participants will be recruited from adults attending the Periodontology Department clinic at Trakya University Faculty of Dentistry (Edirne, Türkiye) for routine dental/periodontal care and professional plaque control. The source population consists of generally healthy dental patients from this outpatient clinic setting who have maxillary anterior vestibular surfaces that can be categorized by existing surface condition/restoration status for observational comparison

Individual participant data (IPD) and data dictionaries will not be made publicly available. The study dataset contains potentially identifiable clinical and imaging-derived information. Only aggregate, de-identified results will be reported in publications and presentations. Access to additional information may be considered on a case-by-case basis upon reasonable request and subject to institutional approvals and applicable regulations.