Dental Biomaterials Department, Faculty of Dentistry, Alexandria University, Champolion St., Azarita, Alexandria, Egypt.
Polymeric Materials Research Department, Advanced Technology and New Materials Research Institute, City of Scientific Research and Technological Applications (SRTA-City), New Borg Al-Arab City, Alexandria, 21934, Egypt.
BMC Oral Health. 2023 Aug 4;23(1):536. doi: 10.1186/s12903-023-03236-z.
In recent years, treated dentin matrix (TDM) has been introduced as a bioactive hydrogel for dentin regeneration in DPC. However, no study has introduced TDM as a photocrosslinkable hydrogel with a natural photoinitiating system. Therefore, the present study aimed to explore the synthesis, characterizations and grafting optimization of injectable gelatin- glycidyl methacrylate (GMA)/TDM hydrogels as a novel photocrosslinkable pulp capping agent for dentin regeneration.
G-GMA/TDM hydrogel was photocrosslinked using a new two-component photoinitiating system composed of riboflavin as a photoinitiator under visible light and glycine as a first time coinitiator with riboflavin. The grafting reaction conditions of G-GMA/TDM e.g. GMA concentration and reaction time were optimized. The kinetic parameters e.g. grafting efficiency (GE) and grafting percentage (GP%) were calculated to optimize the grafting reaction, while yield (%) was determined to monitor the formation of the hydrogel. Moreover, G-GMA/TDM hydrogels were characterized by swelling ratio, degradation degree, and cytotoxicity. The instrumental characterizations e.g. FTIR, H-NMR, SEM and TGA, were investigated for verifying the grafting reaction. Statistical analysis was performed using F test (ANOVA) and Post Hoc Test (P = 0.05).
The grafting reaction dramatically increased with an increase of both GMA concentration and reaction time. It was realized that the swelling degree and degradation rate of G-GMA/TDM hydrogels were significantly reduced by increasing the GMA concentration and prolonging the reaction time. When compared to the safe low and moderate GMA content hydrogels (0.048, 0.097 M) and shorter reaction times (6, 12, 24 h), G-GMA/TDM with high GMA contents (0.195, 0.391 M) and a prolonged reaction time (48 h) demonstrated cytotoxic effects against cells using the MTT assay. Also, the morphological surface of G-GMA/TDM freeze-dried gels was found more compacted, smooth and uniform due to the grafting process. Significant thermal stability was noticed due to the grafting reaction of G-GMA/TDM throughout the TGA results.
G-GMA/TDM composite hydrogel formed by the riboflavin/glycine photoinitiating system is a potential bioactive and biocompatible system for in-situ crosslinking the activated-light pulp capping agent for dentin regeneration.
近年来，处理牙本质基质（TDM）已被引入作为牙本质再生的生物活性水凝胶。然而，目前还没有研究将 TDM 作为一种具有天然光引发体系的光交联水凝胶。因此，本研究旨在探索可注射明胶-甲基丙烯酸缩水甘油酯（GMA）/TDM 水凝胶作为一种新型光交联牙髓盖髓剂用于牙本质再生的合成、特性和接枝优化。
使用由核黄素作为光引发剂和甘氨酸作为核黄素的第一共引发剂组成的新型双组分光引发体系，对 G-GMA/TDM 水凝胶进行光交联。优化 G-GMA/TDM 的接枝反应条件，例如 GMA 浓度和反应时间。计算动力学参数，如接枝效率（GE）和接枝百分比（GP%），以优化接枝反应，同时测定产率（%）以监测水凝胶的形成。此外，通过溶胀比、降解程度和细胞毒性来表征 G-GMA/TDM 水凝胶。通过傅里叶变换红外光谱（FTIR）、核磁共振氢谱（H-NMR）、扫描电子显微镜（SEM）和热重分析（TGA）等仪器特性来验证接枝反应。采用 F 检验（方差分析）和事后检验（P=0.05）进行统计分析。
随着 GMA 浓度和反应时间的增加，接枝反应显著增加。通过增加 GMA 浓度和延长反应时间，发现 G-GMA/TDM 水凝胶的溶胀度和降解率显著降低。与安全的低和中 GM 含量水凝胶（0.048、0.097 M）和较短的反应时间（6、12、24 h）相比，高 GM 含量（0.195、0.391 M）和延长反应时间（48 h）的 G-GMA/TDM 对细胞具有细胞毒性作用，使用 MTT 测定法。此外，由于接枝过程，G-GMA/TDM 冷冻干燥凝胶的形貌表面更加紧密、光滑和均匀。通过 TGA 结果可以看出，由于 G-GMA/TDM 的接枝反应，显著提高了热稳定性。
由核黄素/甘氨酸光引发体系形成的 G-GMA/TDM 复合水凝胶是一种潜在的生物活性和生物相容性体系，可用于原位交联激活光牙髓盖髓剂用于牙本质再生。
