The concept of extrafibrillar demineralization involves selective removal of apatite crystallites from the extrafibrillar spaces of mineralized dentin without disturbing the intrafibrillar minerals within collagen. This helps avoiding activation of endogenous proteases and enables air-drying of partially demineralized dentin without causing collapse of completely demineralized collagen matrix that adversely affects resin infiltration. The objective of the present study was to evaluate the potential of quaternized carboxymethyl chitosan (QCMC)–based extrafibrillar demineralization in improving resin–dentin bond durability. Isothermal titration calorimetry indicated that QCMC synthesized by quaternization of O-carboxymethyl chitosan had moderate affinity for Ca²⁺ (binding constant: 8.9 × 10⁴ M⁻¹). Wet and dry bonding with the QCMC-based demineralization produced tensile bond strengths equivalent to the phosphoric acid (H₃PO₄)–based etch-and-rinse technique. Those bond strengths were maintained after thermocycling. Amide I and PO₄³⁻ mappings of QCMC-conditioned dentin were performed with atomic force microscope–infrared spectroscopy (AFM-IR). Whereas H₃PO₄-etched dentin exhibited an extensive reduction in PO₄³⁻ signals corresponding to apatite depletion, QCMC-conditioned dentin showed scattered dark areas and bright PO₄³⁻ streak signals. The latter were consistent with areas identified as collagen fibrils in the amide I mapping and were suggestive of the presence of intrafibrillar minerals in QCMC-conditioned dentin. Young’s modulus mapping of QCMC-demineralized dentin obtained by AFM-based amplitude modulation–frequency modulation recorded moduli that were the same order of magnitude as those in mineralized dentin and at least 1 order higher than H₃PO₄-etched dentin. In situ zymography of the gelatinolytic activity within hybrid layers created with QCMC conditioning revealed extremely low signals before and after thermocycling, compared with H₃PO₄-etched dentin for both wet and dry bonding. Confocal laser scanning microscopy identified the antibacterial potential of QCMC against Streptococcus mutans and Enterococcus faecalis biofilms. Taken together, the QCMC-based demineralization retains intrafibrillar minerals, preserves the elastic modulus of collagen fibrils, reduces endogenous proteolytic activity, and inhibits bacteria biofilms to extend dentin bond durability.

纤维外脱矿的概念涉及从矿化牙本质的纤维外空间选择性去除磷灰石微晶，而不干扰胶原蛋白内的纤维内矿物质。这有助于避免内源性蛋白酶的活化，并使部分脱矿质牙本质能够风干，而不会导致完全脱矿质的胶原蛋白基质塌陷，从而对树脂浸润产生不利影响。本研究的目的是评估基于季铵化羧甲基壳聚糖 (QCMC) 的纤维外脱矿质在提高树脂-牙本质粘合耐久性方面的潜力。等温滴定量热法表明，O-羧甲基壳聚糖季铵化合成的QCMC对Ca ²⁺具有中等亲和力。(结合常数：8.9 × 10 ⁴ M ^-1 )。使用基于 QCMC 的脱矿质的湿法和干法粘合产生的拉伸粘合强度与基于磷酸 (H ₃ PO ₄ ) 的蚀刻和冲洗技术相当。在热循环后保持这些粘合强度。使用原子力显微镜-红外光谱 (AFM-IR) 进行 QCMC 条件牙本质的酰胺 I 和 PO ₄ ^3-映射。尽管 H ₃ PO ₄蚀刻的牙本质表现出与磷灰石耗尽相对应的 PO ₄ ^3-信号的广泛减少，但 QCMC 处理的牙本质显示分散的暗区和明亮的 PO ₄ ^3-条纹信号。后者与酰胺 I 映射中确定为胶原原纤维的区域一致，并暗示 QCMC 条件牙本质中存在原纤维内矿物质。通过基于 AFM 的幅度调制-频率调制记录的 QCMC 脱矿牙本质的杨氏模量映射与矿化牙本质中的模量相同，并且比 H ₃ PO ₄蚀刻的牙本质至少高 1 个数量级。_{与 H 3} PO ₄相比，使用 QCMC 调节产生的混合层内的明胶分解活性的原位酶谱显示热循环前后的信号极低- 蚀刻牙本质，用于湿粘合和干粘合。共聚焦激光扫描显微镜确定了 QCMC 对变形链球菌和粪肠球菌生物膜的抗菌潜力。总之，基于 QCMC 的脱矿质保留原纤维内矿物质，保持胶原原纤维的弹性模量，降低内源性蛋白水解活性，并抑制细菌生物膜以延长牙本质粘合耐久性。