The objectives of this study are i) to monitor the oral health of young people over a period of one year and ii) to assess the ability of a new intraoral scanner combining fluorescence with 3D imaging to detect and monitor changes in the dental hard tissues in vivo.

The working hypotheses of this study are that i) the monitoring of oral health will benefit from using a new intraoral scanner combining fluorescence with 3D imaging and ii) the new intraoral scanner combining fluorescence with 3D imaging will aid dentists to identify changes in the dental hard tissues at earlier stages than the traditional diagnostic methods (i.e. visual-tactile, radiographic methods).

Currently, monitoring oral health relies mainly on the visual examination of the oral tissues aided electively by radiographic or photographic images. In the context of oral health, monitoring involves detecting changes, sometimes rather subtle, in the soft or hard oral tissues.

The slow rate of change involved in some situations, like loss of mineral tissues due to caries or tooth wear, makes it extremely difficult for the human eye alone to identify them. It is even more challenging to accurately register and recall the original situation on the patient's follow-up visits. Clinical photographs are therefore used to aid the monitoring however, it is difficult to obtain comparable photographs from different points in time and the subjectivity involved in the process cannot be avoided.

Different criteria are used in clinical practice to register and monitor changes in the oral tissues, according to the specific condition under investigation. While identifying significant changes is an easy task, the challenge lies particularly in identifying early, incremental changes. Regarding the detection of caries lesions, a number of initial lesions typically remain unnoticed when visual examination alone is used; or even when radiographs are employed, as the latter are not sensitive to early demineralization in enamel. Concerning tooth wear (i.e. erosion, abrasion, attrition), as the gradual mineral loss occurs progressively and irreversibly, it is usually only noticed when a significant amount of hard dental tissue is already lost.

A promising clinical solution to overcome the challenges involved in the detection of early changes and monitoring of oral tissues is the use of 3D intraoral scans. Obtaining 3D scans directly from the patients (in vivo) using intraoral scanners and by comparing 3D scans obtained from the same patients at different points in time, a less subjective and more reliable comparison of data is expected: the 3D scans can be overlapped and analyzed using specific software. Therefore, it is hypothesized that 3D intraoral scans can be used for more consistent monitoring of oral health in relation to clinical photographs or clinical records.

The current 3D intraoral scanners capture the color of the oral tissues by emitting visible white light. A recently developed 3D intraoral scanner manufactured by 3Shape A/S, Denmark, is also able to emit visible blue light (415 nm wavelength) that allows capturing fluorescence from the oral tissues. Fluorescence is one of the most promising technologies for accurate detection of the early stages of enamel demineralization, but is currently available only in 1D or 2D devices. The main limitation of the existing devices featuring fluorescence, as already mentioned, is the challenge in comparing single images obtained at different points in time, which is at large influenced by imaging artifacts and noise. Imprecision in the comparison of these images compromises the ability to accurately monitor progressive demineralization of the dental hard tissues. There is no intraoral scanner reported in the scientific literature that combines fluorescence with 3D imaging. Thus, the investigators hypothesize that this new intraoral scanner will benefit the monitoring of dental hard tissues and will aid dentists to identify early changes in tissue mineralization. With this method it is only possible to examine the tooth surfaces that are visible and directly exposed into the mouth (i.e. the smooth free surfaces and the occlusal fissures); the areas between the teeth (i.e. the approximal surfaces) cannot be visualized and therefore cannot be examined using the scanner.

A total number of 70 participants will be recruited for the study, including adolescents and young adults (12-19 years old). The oral health of all participants will be examined using visual-tactile and radiographic methods. Subsequently, both the upper and lower jaw of the participants will be scanned using the intraoral scanner (TRIOS 4, 3Shape TRIOS A/S, Denmark). All participants will be monitored for 1 year with follow-up intervals of 3 to 12 months according to the risk group that they are classified into (low, moderate, high). The same clinical procedures will be followed on the follow-up examinations (3 or 6 months) as well as on the final examination (1-year follow-up) The clinical registrations from oral examination using the state-of-the-art methods (visual-tactile, radiographic) will be compared with the outcomes from the assessment using the intraoral scanner.

Inclusion Criteria:

• Participants 12-19 years old without chronic diseases

Exclusion Criteria:

• Participants in need of complex dental treatment (e.g. extensive restorative work, extractions, prosthetic treatment).
• Participants using partial/complete removable dentures or other appliances (i.e. orthodontic).

The participants in this project will be healthy young people 12-19 years old. The adolescents (12-16 years old) will be recruited in Denmark and they will be students from national public schools in the Capital Region of Denmark.

The young adults (18-19 years old) will be recruited in Greece and they will be 1st-year University students at the School of Dentistry of the National and Kapodistrian University of Athens.