Maturational changes in dentin mineral properties

In this study the changes in properties of the maturing mantle and circumpulpal dentin were quantitatively analyzed. Sections from six fetal bovine undecalcified incisors were used. Regions of mantle and circumpulpal dentin of sequential maturation stages were identified on spectroscopic images acquired by Fourier Transform Infrared Imaging. Spectroscopic parameters corresponding to mineral properties at these stages were analyzed and reported as a function of distance from the cervix of the incisor, the latter representing tissue age. Mineral parameters were correlated with distance from the cervix. Values of these parameters in mantle and circumpulpal dentin were compared. A multi-phasic pattern of changes was found for all the parameters examined, with most of the alterations occurring in the initial maturation period. The patterns of temporal variation in mantle and circumpulpal dentin mineral properties show distinct developmental stages and were not identical for the two dentin compartments. The study showed that mineral maturation in dentin is not a linear process and that mantle dentin is developmentally distinct from circumpulpal dentin, presenting at certain stages different physicochemical events during the maturation of the tissue

The effect of universal adhesives on dentine collagen

Objectives: The purpose of the study was to evaluate the integrity of dentine type I collagen after self-etching (SE) treatments with strong and mild universal adhesives. Methods: Coronal dentine specimens (n = 10/product) were imaged by optical microscopy and analyzed by ATR-FTIR spectroscopy before and after treatment with 32% phosphoric acid gel (PA-negative control), 17% neutral EDTA (ED-positive control) conditioners and Adhese Universal (AD), Clearfil Universal Bond Quick (CQ), G-Premio Bond (GP), Prelude One (PR) and Scotchbond Universal (SB) adhesives. From the spectroscopic analysis the following parameters were determined: a) Extent of dentine demineralization (DM%) and b) percentage area of the Amide I curve-fitted components of β-turns, 310-helix/β-turns, α-helix, random coils, β-sheets and collagen maturation (R) index. Statistical analysis was performed by one-way ANOVA (DM%), paired t-test/Wilcoxon test (Amide I components) and Spearman correlation coefficient (DM% vs Amide I components) at an a = 0.05 level. Results: PA, ED and GP removed the smear-layer and opened tubule orifices, whereas all other treatments removed only the intratubular smear-layer fraction. The ranking of the statistically significant differences in DM% was PA > GP > ED > AD, SB, CQ, PR, with AD being significantly different from PR. Regarding the Amide I components, PA demonstrated a significant reduction in β-turns, α-helices and an increase in β-sheets, GP a reduction in β-turns, AD an increase in β-turns and random coils, and CQ an increase in β-turns. PR, SB and ED showed insignificant differences in all the Amide I components. Significant correlations were found between DM%-random coils and DM%-R. Significance: The universal adhesives used in the SE mode induced none to minimal changes in dentine collagen structure, without evidence of the destabilization pattern observed after conventional phosphoric acid treatments. © 2021 The Academy of Dental Material