Hexahedrally based crystals in human tooth enamel

Area of Science:

• Dental research
• Mineralogy
• Biomineralization

Background:

• Human tooth enamel is primarily composed of hydroxyapatite.
• The presence and significance of other mineral phases, like Mg-containing calcium phosphates, are less understood.
• Enamel's structural integrity is crucial for oral health.

Purpose of the Study:

• To identify and characterize Mg-containing calcium phosphate crystals in human tooth enamel.
• To investigate the location and prevalence of these crystals in different enamel types (young, old, carious, caries-free).
• To determine the potential role of these crystals in enamel aging and caries progression.

Main Methods:

• Scanning electron microscopy (SEM) for morphological analysis.
• Electron probe microanalysis (EPMA) for elemental composition.
• Microscopic examination of human tooth enamel samples.

Main Results:

• Mg-containing calcium phosphate crystals, identified as whitlockite, were observed in human tooth enamel.
• Crystals exhibited various shapes (pseudocuboidal, rhombohedral, quadrangular blades) and were found in tufts and lamellae.
• These crystals were more prevalent in older, caries-free enamel and in lamellae of arrested caries, often adjacent to partially dissolved prisms.
• Crystal presence was rare in young, sound enamel and inner crevices of deciduous enamel.

Conclusions:

• Mg-containing whitlockite crystals are a component of human tooth enamel.
• Their presence increases with tooth age and is associated with arrested caries.
• These crystals likely grow over extended periods, potentially influencing enamel structure and caries dynamics.