Background Dental cusp angulation provides valuable insights into chewing efficiency and prosthesis safety. Artificial intelligence-enabled computing of cusp angles has potential important value, but there is currently no reliable digital measurement method as a cornerstone.

Objectives To establish a digital method for measuring cusp angles and investigate inter-rater and intra-rater reliabilities.

Methods Two cusp angles (angles α and β) of the first molar were measured on 21 plaster casts using a goniometer and on their corresponding digital models using PicPick software after scanning with a CEREC Bluecam three-dimensional (3D) intraoral scanner. Means ± standard deviations, as well as intraclass correlation coefficients (ICCs) and Pearson's correlation coefficients (PCCs) were calculated, and repeated measures analysis of variance was performed. The Bland–Altman method was used to calculate the difference and mean degree values of two measurement methods from both examiners, and the Bland–Altman diagram was drawn using MedCalc software.

Results When the examiner was experienced, angle α was 139.19° ± 13.86°, angle β was 19.25° ± 6.86°, and a very strong positive correlation between the two methods was found (r > 0.9; p < 0.001). No significant difference between the two methods was found using the repeated measures analysis of variance (p > 0.05). The Bland–Altman diagram showed that the two methods were highly consistent. For inter-rater assessments, the ICC and PCC values of the cusp angulation using the digital method were all higher than the corresponding values measured on traditional casts. For intra-rater assessments, the ICC values of cusp angulation using the digital method were higher than the corresponding values measured on traditional plaster casts for both examiners. However, repeated measurements of the angle β of the inter-examiners revealed significant differences (p < 0.05) for both methods.

Conclusions Cusp angulation using 3D digital models is a clinical option and appears to improve the reliability of cusp angulation compared with measuring plaster casts using a goniometer. This variability was still evident when measuring small cusp angles using the digital model for inexperienced examiners.

背景 牙尖角度为咀嚼效率和修复体安全提供了宝贵的见解。基于人工智能的尖角计算具有潜在的重要价值，但目前还没有可靠的数字测量方法作为基石。

目的 建立一种测量尖角的数字方法，并研究评估者间和评估者内的信度。

方法 在使用 CEREC Bluecam 三维 (3D) 口内扫描仪扫描后，使用测角仪在 21 个石膏模型上测量第一磨牙的两个尖角（角度 α 和 β），并使用 PicPick 软件测量它们相应的数字模型。计算平均值±标准差，以及组内相关系数（ICCs）和皮尔逊相关系数（PCCs），并进行重复测量方差分析。采用Bland-Altman法计算两位考官两种测量方法的度数差值和均值，并使用MedCalc软件绘制Bland-Altman图。

结果 考官经验丰富时，α角为139.19°±13.86°，β角为19.25°±6.86°，两种方法呈极强正相关（r  >0.9；p  <0.001）。使用重复测量方差分析发现两种方法之间没有显着差异（p > 0.05)。Bland-Altman 图显示这两种方法高度一致。对于评估者间评估，使用数字方法的牙尖角的 ICC 和 PCC 值均高于在传统管型上测量的相应值。对于评估者内评估，使用数字方法的尖角的 ICC 值高于两位检查者在传统石膏模型上测量的相应值。然而，对相互检查者的角度 β 的重复测量显示两种方法存在显着差异 ( p  < 0.05)。

结论 使用 3D 数字模型的牙尖角度是一种临床选择，与使用测角仪测量石膏模型相比，似乎可以提高牙尖角度的可靠性。当使用数字模型为没有经验的检查者测量小尖角时，这种可变性仍然很明显。