Questions about the numerical value and quantitative data transfer of tooth preparation-from experience guidance to digital guidance.

Tooth preparation is a common operation in dental clinical practice. This procedure is irreversible and invasive from the point of view of tooth preservation. Conditions of the abutment tooth, treatment methods, and restoration materials for target restoration affect tooth preparation. To achieve the goals of tooth tissue preservation, dental pulp protection, and periodontal health, dentistry professionals agreed on the importance of minimizing the amount of tooth reduction. The foundations for realizing this consensus are as follows. First, the available restoration materials with improved comprehensive performance need less target restoration space. Next, teeth can be prepared under a digital guide, and the real-time measurement of restoration space can be verified due to the invention of digital technologies for the analysis of the quantity and shape of the prepared tooth and tooth measurement. Moreover, guiding methods for preparation have been developed from freehand operation under the naked eye based on accumulated personal experience to digital-guidance jointing microscope. These innovations indicate the creation of a prototype of guided prosthodontics that is precise and applies real-time measurement throughout the process of tooth preparation. From the perspective of the evolution of digital, guided, and micro prosthodontics, this article raised seven questions about the numerical value and quantitative data transfer of tooth preparation and evaluated the authenticity of existing numerical requirements from the perspective of the four elements of measurement. Identifying unified measuring methods and developing measuring tools with a precision of hundred or ten microns will be the key to solving the problem about the authenticity of numerical measurement. Furthermore, this paper summarizes the methods of how to control tooth reduction and explains in depth why the currently dominant tooth preparation technology, which is based on empiricism, cannot effectively achieve the goals in digital prosthodontics. Therefore, we strongly call for rebuilding the digital foundation of prosthodontic treatment immediately.不同修复方式及材料选择、拟预备牙体本身条件等都会对牙体预备手术产生影响。为了牙体保存、活髓保护及牙周健康等共识理念的实现，牙体预备量总体越少越好已成共识。支撑其实现的条件一是备选修复材料的综合性能进步、材料所需承载空间有效减少；二是预备量和形的数字化分析及实测技术的出现，使得导板下备牙量与修复空间全程实测核查成为可能，预备手术的引导方式也从凭借个人经验累积的目测徒手操作，发展到了采用数字引导联合显微操作进行等。这些进展也标志着精准的、可全程实测核查的引导式修复学的形成。本文将从数字化修复、引导式口腔修复及显微修复技术的视角，对牙体预备的数值要求与数量关系转移展开数字追问；并从测量四要素对现有数值要求做论证评价，指出统一测量方法、研发百微米、十微米级及角度的测量工具将是解决数据可信度的重点；同时也对牙体预备量的引导方式进行归纳梳理，进一步解读了为什么目测经验类比为逻辑基础的当前主流修复技术基础无法有效支撑数字化修复的原委，强烈呼吁尽快打造口腔修复的数字基础。.