Pulp response of hypomineralised first permanent molars: an in vitro study

Abstract

Background: Dentine hypersensitivity is common among children with MIH. The weaker and porous enamel in hypomineralised first permanent molars results in post-eruptive breakdown that can lead to pain and infection at a rapid rate. This can have a negative effect on children’s quality of life. The understanding behind dentine hypersensitivity remains unclear. More research is required detailing the pulp response of hypomineralised first permanent molars. Aims: This in vitro study sought to i. explore a new standardised protocol for histological study on sound teeth and its feasibility on hypomineralised first permanent molars. ii. investigate the pulp response of hypomineralised first permanent molars with respect to defect severity. Methodology: Mild and severe hypomineralised first permanent molars (n=17) were fixated in 4% formaldehyde solution, demineralisation used 17% EDTA for 8 weeks and processed for histological study following a standardised approach. Samples were cut at 4 μm thickness and stained with H&E. Microscopic imaging was obtained for each slide. Three different areas of interest were identified for qualitative analysis. Two classification systems were used to identify the pulp response. The first classification system identified inflamed from healthy pulp. The following classification categorised the pulp response as reversible or irreversible. Results: H&E staining revealed evidence of reactive tertiary dentine deposition, degenerative odontoblast cells, accumulation of inflammatory cells, and an increase in nerve fibres within the dentine-pulp complex of mild and severe hypomineralised first permanent molars indicating an inflammatory pulp response. Conclusions: An inflammatory response was evident in the dentine-pulp complex of mild and severe hypomineralised molars. The hard and soft tissue changes may help further explain the hypersensitivity seen in some children with MIH.