Masticatory function induced changes, at subnanostructural level, in proteins and mineral at the resin-dentine interface.

Objective: This study evaluated the ability of different in vitro mechanical loading tests to promote new mineral formation at the bonded dentine interfaces created with a two-step self-etching resin adhesive.

Methodology: Restored teeth were divided in the following groups: (1) unloaded, load cycling with (2) sine waveform, (3) square waveform, and hold waveform for (4) 24h, and (5) 72 h. Raman spectroscopy and cluster analysis were used to assess the resin-dentine interface.

Results: Mechanical loading in CSEB-treated samples promoted a generalized increase of relative presence of minerals and ratio of phosphate peaks, except in square waveform, where the nature of collagen resulted damaged. Crystallinity of carbonate was higher than phosphate. The organic component showed, in general terms, an increase in crosslinking. Molecular orientation (α-helices) peaks augmented in all tests. Pentosidine vibration increases in all tests, except in hold 72 h. Ratios amide I and II/CH2 incremented, in general. Non uniform parameters of Bis-GMA and adhesive penetration were encountered, as both increased at the bottom of the hybrid layer when loading square and hold 72 h were applied.

Significance: Functional remineralisation at the resin-dentine interface was attained after in vitro mechanical stimuli application. When loading in square waveform, the lowest vibrations to favor remineralisation were attained.