This study tests the remineralization of donor teeth (donorMIH) in situ in participants using 10% hydroxyapatite (HAP) toothpaste and sodium fluoride toothpaste.

Prior to each 2-week treatment phase, subjects will complete a 1-week washout period. Following the washout period, the intra-oral appliance containing a donorMIH tooth block will be fitted to each subject by a qualified dentist. Immediately after fitting of the first appliance (on day 1 of the first treatment phase), each subject will receive a soft bristled manual toothbrush for use throughout the duration of the study and a toothpaste according to the treatment phase. Subjects will be instructed to brush their teeth with the appliance in the mouth, two times daily, for 3 minutes on each brushing episode, in the morning after breakfast and last thing before bed, then rinsing with 10 ml of water. Over the study period, all subjects will maintain their normal dietary habits.

A 7-day washout period without an appliance will follow. After completion of the second washout period, subjects will return to the clinic, and the appliance, with another MIH-bearing tooth blocks mounted, will be fitted to the subject for the phase 2 treatment period. This procedure will then be repeated until the 2-week treatment phase is completed, and each subject has gone through the two arms of the study.

Inclusion Criteria:

• 18-60 years of age
• Good general health
• No known history of allergy to personal care/consumer products
• Minimum of 20 natural uncrowned teeth (excluding third molars)
• Normal salivary flow rate (stimulated and unstimulated flow of ≥0.7 ml/min and ≥0.2 ml/min respectively
• Able to consent
• Availability throughout entire study
• Willing to wear intra-oral appliance 24 hours per day
• Willing to use only assigned products for oral hygiene for duration of study

Exclusion Criteria:

• Advanced periodontal disease
• A medical condition that requires pre-medication prior to dental visits/procedures
• Impaired salivary function
• Orthodontic retainer(s)
• Too few teeth to secure the oral appliance
• Disease of the soft or hard oral tissues
• Use of drugs that can affect salivary flow
• Use of antibiotics one month prior to or during this study
• Participation in another clinical study one week prior to the start of washout period or during this study period
• Allergic hisotry to common toothpaste ingredients
• Compromised immune system (HIV, AIDS, Immunosuppressive drug therapy)

From baseline to study end at 2 weeks

The study will be blinded to both the study team and the subjects.