Rajan Sheetal Maria, Shrestha Barsha, Fawzy Amr
Dental School, The University of Western Australia, 17 Monash Avenue, Nedlands, WA, 6009, Australia.
J Transl Med. 2025 Jan 8;23(1):29. doi: 10.1186/s12967-024-06008-7.
Treatment of deep carious lesions poses significant challenges in dentistry, as complete lesion removal risks compromising pulp vitality, while selective removal often reduces the longevity of restorations. Herein, we propose a minimally invasive approach using High-Intensity Focused Ultrasound (HIFU) for microscale removal of carious dentine. Concurrently, HIFU's antimicrobial effects against associated cariogenic biofilms and the corresponding thermal and biological impacts on surrounding tissues were investigated.
A total of 238 sound human molars were utilized, with 203 samples of artificial carious-simulated dentine (ACSD) prepared for HIFU exposure. HIFU (250 kHz) was applied at 20 W for varying durations (60, 120, and 180 s). The acoustic waves were administered via a collimated cone coupled to the dentine surface using ultrasonic gel.
Advanced characterization techniques including scanning electron microscopy (n = 5/group), Raman spectroscopy, atomic force microscopy, and nano-indentation (n = 5/group), demonstrated HIFU's effectiveness in removing demineralized collagen-fibrils. This was reflected in the increased mineral content, nano-hardness, and reduced elastic-modulus of ACSD lesions. Micro-CT (n = 6/group) confirmed the increase in mineral density post-HIFU exposure. Confocal microscopy of Rhodamine-B stained ACSD (n = 5/group) quantified the depth of dentine microscale removal post-HIFU exposure in a time-dependent manner. HIFU's potent anti-biofilm effect (n = 9/group) against Streptococcus mutans biofilms was evidenced by microscopic characterizations and significant reductions in metabolic-activity and colony-forming units. Furthermore, HIFU promoted the proliferation of dental pulp stem cells (n = 3/group) while maintaining the associated temperature-rise within the physiological tolerance.
HIFU's potential as an innovative, minimally invasive, non-ionizing tool for dentine carious lesion micromanipulation was demonstrated through the interaction between focused acoustic waves and dentine, warranting further studies for future clinical translation in restorative and/or preventive dentistry.
在牙科领域，治疗深龋病变面临重大挑战，因为完全去除病变组织有损害牙髓活力的风险，而选择性去除往往会降低修复体的使用寿命。在此，我们提出一种使用高强度聚焦超声（HIFU）进行微尺度去除龋坏牙本质的微创方法。同时，研究了HIFU对相关致龋生物膜的抗菌作用以及对周围组织相应的热影响和生物学影响。
共使用了238颗健康人磨牙，制备了203个模拟人工龋坏牙本质（ACSD）样本用于HIFU照射。以20W的功率施加250kHz的HIFU，持续不同时间（60、120和180秒）。通过使用超声凝胶耦合到牙本质表面的准直圆锥体施加声波。
包括扫描电子显微镜（每组n = 5）、拉曼光谱、原子力显微镜和纳米压痕（每组n = 5）在内的先进表征技术表明，HIFU在去除脱矿化胶原纤维方面是有效的。这反映在ACSD病变的矿物质含量增加、纳米硬度增加和弹性模量降低上。显微CT（每组n = 6）证实了HIFU照射后矿物质密度增加。对罗丹明B染色的ACSD进行共聚焦显微镜检查（每组n = 5），以时间依赖性方式量化了HIFU照射后牙本质微尺度去除的深度。微观表征以及代谢活性和菌落形成单位的显著降低证明了HIFU对变形链球菌生物膜具有强大的抗生物膜作用（每组n = 9）。此外，HIFU促进了牙髓干细胞的增殖（每组n = 3），同时将相关温度升高维持在生理耐受范围内。
通过聚焦声波与牙本质之间的相互作用，证明了HIFU作为一种用于牙本质龋病变微操作的创新、微创、非电离工具的潜力，值得在修复和/或预防牙科的未来临床转化方面进行进一步研究。
