Professor and Director, Division of Prosthodontics, University of Minnesota School of Dentistry, Minneapolis, Minn.
Dental student, University of Minnesota School of Dentistry, Minneapolis, Minn.
J Prosthet Dent. 2023 Dec;130(6):878-884. doi: 10.1016/j.prosdent.2022.01.010. Epub 2022 Feb 17.
Limited data, especially in vivo data, exist regarding translucency parameter (TP) values for vital anterior nonrestored dentition. Additionally, published information on the CIELab values of vital enamel at a theoretical infinite thickness is lacking. Obtaining TP and CIELab values in a population that varies in terms of ethnicity, age, and sex would be useful to inform the development and placement of esthetic dental restorations that more accurately capture the complex optical qualities of enamel.
The purpose of this clinical study was to investigate in vivo the TP and CIELab values of vital anterior incisor enamel at a theoretical infinite thickness in a diverse pool of participants who varied in age, ethnicity, and sex.
Spectral reflectance measurements (380 to 780 nm at 2-nm intervals) of the mid-incisal region of vital, unrestored maxillary anterior teeth were made in 120 participants, equally divided into 2 sexes, 4 racial or ethnic groups, and 5 age ranges. Instruments were oriented to achieve 0-degree observation and 45-degree illumination, and spectral measurements were made with white and black silicone backgrounds. Reflectance spectra of the incisal enamel from both the black and white silicone backing were used to fit to the Kubelka-Munk (K-M) reflectance theory. The CIEDE2000 color difference formula was used to determine TP, and data were compared among participant demographics. CIELab color coordinate values for enamel at an infinite thickness were calculated by using a D65 illumination and CIE standard human (2-degree) observer. To determine value ranges and significant differences among participant groups, CIELab values were analyzed with a 4-way ANOVA, and TP values were analyzed with a generalized linear mixed model. Pairwise comparisons of interest were evaluated with Bonferroni-corrected Student t tests.
For maxillary central incisor enamel, the average TP was 10.1 ±3.6, and the average CIELab color coordinates were L∗=73.5 ±7.6, a∗=2.2 ±1.8, b∗=11.9 ±8.4. TP values of incisal enamel significantly differed among specific age and ethnic groups, with general significant interactions of age and sex (P=.009), as well as ethnicity and age (P=.042). CIE color coordinates of enamel at an infinite thickness were found in the L∗ coordinate among different age groups with the same sex and ethnicity, specifically when comparing CIELab direction with the population characteristics of age (P=.011) and the interaction between age, sex, and ethnicity (P=.035).
In vivo L∗ values and TP values of incisal enamel differed significantly among groups determined by ethnicity, age, and sex.
关于有活力的前牙非修复体的透明度参数 (TP) 值，只有有限的数据，特别是体内数据。此外，关于理论上无限厚度的活力釉质的 CIELab 值的已发表信息也缺乏。在不同种族、年龄和性别的人群中获得 TP 和 CIELab 值，将有助于为更准确地捕捉釉质复杂光学特性的美容牙科修复体的开发和放置提供信息。
本临床研究的目的是在一个由不同年龄、种族和性别的参与者组成的多样化人群中，研究有活力的上颌前切牙釉质在理论上无限厚度时的 TP 和 CIELab 值。
对 120 名参与者上颌前牙切缘中部进行光谱反射率测量（380 至 780nm，间隔 2nm），将参与者等分为 2 组，4 个种族或族群，5 个年龄组。仪器的方向设置为实现 0 度观察和 45 度照明，并用白色和黑色硅酮背景进行光谱测量。用黑色和白色硅酮背板的切缘釉质反射光谱拟合 Kubelka-Munk (K-M) 反射理论。用 CIEDE2000 色差公式确定 TP，并比较参与者人口统计学特征之间的差异。用 D65 照明和 CIE 标准人（2 度）观察者计算无限厚度釉质的 CIELab 颜色坐标值。为了确定参与者群体之间的值范围和显著差异，用 4 因素方差分析分析 CIELab 值，用广义线性混合模型分析 TP 值。用 Bonferroni 校正的学生 t 检验评估感兴趣的成对比较。
上颌中切牙釉质的平均 TP 为 10.1±3.6，平均 CIELab 颜色坐标为 L*=73.5±7.6，a*=2.2±1.8，b*=11.9±8.4。切缘釉质的 TP 值在特定年龄和种族群体之间存在显著差异，并且年龄和性别（P=.009）以及种族和年龄（P=.042）有一般显著的相互作用。在具有相同性别和种族的不同年龄组中，在无限厚度的釉质的 CIE 颜色坐标中，L*坐标存在差异，具体表现在 CIELab 方向与人口特征的年龄（P=.011）和年龄、性别和种族之间的相互作用（P=.035）。
在由种族、年龄和性别决定的群体中，切缘釉质的 L*值和 TP 值存在显著差异。
