Dentin and Enamel Exposure on Upper Incisors for Bonding Buccal Laminated Veneers: Method Validation and Ex Vivo...

This study compared the accuracy of postetching macrophotography, a clinically applicable method, with microscope observation (the laboratory reference) for quantifying enamel and dentin surfaces. A secondary objective was to assess the proportion of exposed dentin and enamel at different veneer preparation depths and to develop a classification system to optimize bonding protocols based on dentin exposure.

Twenty-five human maxillary incisors underwent three sequential buccal reduction steps corresponding to ceramic laminate veneer (LV) preparation: minimally invasive preparation (MIP), semi-invasive preparation (SIP), and invasive preparation (IP). After each preparation step, teeth were etched with 37% orthophosphoric acid for 15 s and subsequently evaluated using optical microscopy at 20× magnification and standardized postetching macrophotography. Enamel and dentin surfaces were quantified on both image sets using ImageJ software.

During MIP, no dentin was exposed. After SIP, dentin exposure averaged 22% ± 20% for central incisors and 22% ± 15% for lateral incisors (p = 0.93). After IP, dentin exposure increased to 84% ± 3% for central incisors and 69% ± 14% for lateral incisors (p = 0.0002). No significant differences were found between the methods in measuring the proportions of dentin.

Postetching macrophotography provided dentin-exposure measurements comparable to the reference optical microscopy method, supporting its use as a reliable and clinically applicable assessment tool. MIP and SIP preserved the majority of enamel in maxillary incisors, ensuring favorable bonding. A three-stage classification system based on dentin exposure was developed to help practitioners adapt bonding protocols.

This classification system, combined with a method for assessing residual enamel, offers a guide for customizing bonding protocols in veneer preparation.