What is the most effective combination of non-invasive interventions to reduce hypersensitivity in Mexican children with molars affected by molar incisor hypomineralisation (MIH)?

The participants will be divided into four intervention groups using a randomisation list generated by a website (http://www.randomization.com) A, B, C and D: Group A: Glass-ionomer sealant 0.30 g (Fuji TRIAGE pink, GC Corp. Japan) placed onto MIH-affected molars that show hypersensitivity and professional topical application of 5% sodium fluoride varnish with casein phosphopeptide amorphous calcium phosphate (CPP-ACP) (MI Varnish, GC Corp., Japan) four applications with a one-week interval between applications. Group B: Glass-ionomer sealant 0.30 g (Fuji TRIAGE pink) placed onto MIH-affected molars that show hypersensitivity and use of topical tooth crème with 10% CPP-ACP (MI Paste; GC Corp., Japan) twice-a-day for 12 weeks. Group C: Glass-ionomer sealant (Fuji TRIAGE pink) placed onto MIH-affected molars that show hypersensitivity, professional topical application of 5% sodium fluoride varnish with CPP-ACP (MI Varnish) four applications with a one- week interval between applications and use of topical tooth crème with 10% CPP-ACP (MI Paste) twice-a-day for 12 weeks. Group D: Professional topical application of 5% sodium fluoride varnish with CPP-ACP (MI Varnish) four applications with a one-week interval between applications and use of topical tooth crème with 10% CPP-ACP (MI Paste) twice-a-day for 12 weeks. In groups A, B and C the MIH-affected molars will be cleaned using a gentle no invasive technique with a wet prophylaxis brush to limit discomfort, isolation using cotton rolls and a four-handed technique. For mixing GIC, the capsule will be activated and triturated according to manufacturer´s instructions. The teeth will be dried with cotton pellets. The GIC will be applied to the MIH lesion(s) and pits and fissures, with the material adapted to the tooth surface using a finger press method. Then exposed to a curing light to speed setting time, and cocoa butter applied to protect the GIC. In Groups A, C and D the teeth will be dried with cotton pellets and NaF varnish applied as a thin, uniform layer over the MIH lesion with a micro-brush. For participants who receive the sealant, the fluoride varnish will be applied one week after sealant application. In Groups B, C and D, a topical tooth crème (MI Paste) will be applied at home twice-a-day for 12 weeks, once in the morning after tooth-brushing and once in the evening after tooth-brushing, before going to bed. A small pea-sized (approx. 1 g) amount of product will be applied across the MIH affected tooth surfaces with a clean finger. For ethical reasons we do not have a separate control group, since we cannot leave any participant without treatment, for this reason all the participants will act as the control at follow-up. Thus, in all, there will be a use of a preventive standard therapy which means, age-appropriate toothbrush, sodium fluoride toothpaste 1450 ppm, brushing technique instruction and dietary advice. All participants will be instructed not to eat anything, or to brush their teeth for at least four hours after the application of MI Paste.

o Children (male and female), aged from 6 to 13 years. o At least one MIH-affected first permanent molar with self-reported hypersensitivity symptoms (to changes in temperature and/or dental brushing) o At least response grade “1” on the Schiff Cold Air Sensitivity Scale SCASS.

o Other developmental defects of enamel such as fluorosis and amelogenesis imperfecta o Teeth of interest with restorations, PEB, or carious lesions classified as score >2 according to the International Caries Detection and Assessment System (ICDAS) o Allergy to milk proteins and/or hydroxybenzoate