Lancaster P E, Carmichael F A, Clerehugh V, Brettle D S
Department of Restorative Dentistry, School of Dentistry, University of Leeds, Leeds, United Kingdom.
Department of Dental and Maxillofacial Radiology, Leeds Dental School, Leeds, United Kingdom.
Front Physiol. 2022 Oct 24;13:993674. doi: 10.3389/fphys.2022.993674. eCollection 2022.
Human enamel and dentin temperatures have been assessed with non-contact infrared imaging devices for safety and diagnostic capacity and require an emissivity parameter to enable absolute temperature measurements. Emissivity is a ratio of thermal energy emitted from an object of interest, compared to a perfect emitter at a given temperature and wavelength, being dependent on tissue composition, structure, and surface texture. Evaluating the emissivity of human enamel and dentin is varied in the literature and warrants review. The primary aim of this study was to evaluate the emissivity of the external and internal surface of human enamel and dentin, free from acquired or developmental defects, against a known reference point. The secondary aim was to assess the emissivity value of natural caries in enamel and dentin. Fourteen whole human molar teeth were paired within a thermally stable chamber at 30°C. Two additional teeth (one sound and one with natural occlusal caries-ICDAS caries score 4 and radiographic score RB4) were sliced and prepared as 1-mm-thick slices and placed on a hot plate at 30°C within the chamber. A 3M Scotch Super 33 + Black Vinyl Electrical Tape was used for the known emissivity reference-point of 0.96. All samples were allowed to reach thermal equilibrium, and a FLIR SC305 infrared camera recorded the warming sequence. Emissivity values were calculated using the Tape reference point and thermal camera software. The external enamel surface mean emissivity value was 0.96 (SD 0.01, 95% CI 0.96-0.97), whereas the internal enamel surface value was 0.97 (SD 0.01, 95% CI 0.96-0.98). The internal crown-dentin mean emissivity value was 0.94 (SD 0.02, 95% CI 0.92-0.95), whereas the internal root-dentin value was 0.93 (SD 0.02, 95% CI 0.91-0.94) and the surface root-dentin had a value of 0.84 (SD 0.04, 95% CI 0.77-0.91). The mean emissivity value of the internal enamel surface with caries was 0.82 (SD 0.05, 95% CI 0.38-1.25), and the value of the internal crown-dentin with caries was 0.73 (SD 0.08, 95% CI 0.54-0.92). The emissivity values of sound enamel, both internal and external, were similar and higher than those of all sound dentin types in this study. Sound dentin emissivity values diminished from the crown to the root and root surface. The lowest emissivity values were recorded in caries lesions of both tissues. This methodology can improve emissivity acquisition for comparison of absolute temperatures between studies which evaluate thermal safety concerns during dental procedures and may offer a caries diagnostic aid.
人们已使用非接触式红外成像设备评估人牙釉质和牙本质的温度，以确保安全性和诊断能力，并且需要一个发射率参数来进行绝对温度测量。发射率是指在给定温度和波长下，感兴趣物体发射的热能与理想发射体发射的热能之比，它取决于组织成分、结构和表面纹理。文献中对人牙釉质和牙本质发射率的评估各不相同，值得进行综述。本研究的主要目的是针对一个已知参考点，评估无后天或发育缺陷的人牙釉质和牙本质内外表面的发射率。次要目的是评估牙釉质和牙本质中自然龋的发射率值。14颗完整的人磨牙在30°C的热稳定室内配对。另外两颗牙齿（一颗完好，一颗有自然咬合龋——国际龋病检测和评估系统（ICDAS）龋病评分为4，放射学评分为RB4）被切片并制备成1毫米厚的薄片，放置在室内30°C的热板上。使用3M思高超级33 +黑色乙烯基电工胶带作为已知发射率参考点，其值为0.96。所有样本均达到热平衡后，用FLIR SC305红外热像仪记录升温过程。发射率值使用胶带参考点和热像仪软件进行计算。牙釉质外表面的平均发射率值为0.96（标准差0.01，95%置信区间0.96 - 0.97），而牙釉质内表面的值为0.97（标准差0.01，95%置信区间0.96 - 0.98）。牙冠内部牙本质的平均发射率值为0.94（标准差0.02，95%置信区间0.92 - 0.95），而牙根内部牙本质的值为0.93（标准差0.02，95%置信区间0.91 - 0.94），牙根表面牙本质的值为0.84（标准差0.04，95%置信区间0.77 - 0.91）。有龋损的牙釉质内表面平均发射率值为0.82（标准差0.05，95%置信区间0.38 - 1.25），有龋损的牙冠内部牙本质的值为0.73（标准差0.08，95%置信区间0.54 - 0.92）。本研究中，完好牙釉质的内外发射率值相似，且高于所有完好牙本质类型的发射率值。完好牙本质的发射率值从牙冠到牙根及牙根表面逐渐降低。两种组织的龋损病变处记录到最低发射率值。这种方法可以改进发射率的获取，以便在评估牙科手术中的热安全问题的研究之间比较绝对温度，并且可能有助于龋病诊断。
