Hydroxyapatite Toothpastes and Enamel Remineralization:

To assess enamel demineralization using the International Caries Detection and Assessment System (ICDAS) recorded through DIAGNOcam transillumination images. The PI will assign ICDAS scores to the occlusal surfaces of permanent molars and labial surfaces of upper central incisors at each timepoint. The ICDAS scoring system ranges from 0 to 6, where a score of 0 indicates sound tooth structure, scores of 1 and 2 represent initial changes in enamel, and scores from 3 to 6 reflect progressive levels of localized enamel breakdown and cavitation. A decrease in score over time is interpreted as a sign of remineralization or lesion arrest.

To evaluate dentin hypersensitivity in response to an air stimulus applied to exposed cervical surfaces using the Schiff Air Index. The clinician will assign a score from 0 to 3, where a score of 0 indicates no reaction, 1 indicates a reaction without the patient requesting discontinuation, 2 indicates a reaction and a request to stop, and 3 indicates a strong reaction and immediate request to discontinue. The score reflects the participant's response to air-blast stimulation and will be recorded at each timepoint. A decrease in score suggests reduced hypersensitivity.

To monitor changes in enamel erosion using the Basic Erosive Wear Examination (BEWE) index. The examiner will assess each sextant and assign a score from 0 to 3. A score of 0 indicates no erosive tooth wear, a score of 1 indicates initial surface loss, a score of 2 represents distinct defects with hard tissue loss involving less than 50% of the surface area, and a score of 3 indicates hard tissue loss affecting more than 50% of the surface. The highest score per sextant is recorded, and a cumulative BEWE score is calculated for each participant at every timepoint. A reduction in the BEWE score suggests improved enamel preservation.

To evaluate changes in plaque accumulation between groups using the Plaque Index (Silness and Löe, 1964), which measures plaque thickness along the gingival margin. The scoring system ranges from 0 to 3. A score of 0 indicates no plaque. A score of 1 corresponds to a thin film of plaque adhering to the free gingival margin and adjacent area of the tooth, which is only detectable by running a probe across the tooth surface. A score of 2 represents moderate accumulation of soft deposits visible to the naked eye, either on the tooth surface or within the gingival margin. A score of 3 indicates heavy accumulation of soft debris in the gingival pocket or on the tooth and gingival margin. The PI assigns a score for each examined surface, and the average value per participant is calculated at each timepoint (T0-T3).

To assess changes in gingival inflammation by comparing Bleeding Index (BI) values between groups at each study timepoint. The clinician will gently probe the gingival sulcus of selected teeth and assign a score from 0 to 3 for each site. A score of 0 indicates no bleeding after probing. A score of 1 indicates isolated bleeding spots visible after probing. A score of 2 indicates a line of blood along the gingival margin. A score of 3 indicates profuse bleeding immediately after probing. The average score per participant will be calculated based on all examined sites at each timepoint. Higher scores reflect greater gingival inflammation.

To evaluate changes in extrinsic dental staining using the Modified Lobene Stain Index, which assesses both the area and intensity of stain on selected tooth surfaces. The PI assigns a score from 0 to 3 for the area of stain, where 0 indicates no staining and 3 indicates stain covering more than two-thirds of the surface. Separately, the intensity of stain is scored from 0 to 3, where 0 indicates no stain and 3 indicates heavy dark staining. The final index is obtained by multiplying the area score by the intensity score. Higher values reflect more extensive and intense staining. Measurements are collected at baseline and at each follow-up (T0-T3).

To evaluate subjective satisfaction with the assigned toothpaste at the end of the study using a self-administered questionnaire. Participants will rate various aspects such as taste, texture, perceived effectiveness, and overall satisfaction. The PI will collect and score responses using a standardized Likert-type scale ranging from 1 (very dissatisfied) to 5 (very satisfied). The mean satisfaction score per participant will be analyzed and compared between the groups.