The primary goal of tooth preparation in restorative dentistry is to perform tooth reduction that ensures adequate support for the retentive element. This reduction creates the necessary space for restorative materials while preserving tooth structure for strength and longevity. Proper preparation shapes the tooth to enhance mechanical retention, resistance, and structural durability of the restoration. Without adequate reduction, the restoration may fail due to insufficient thickness or poor retention, leading to fractures or dislodgement. This foundational step is critical to the success of fixed restorations such as crowns or bridges.

Reference: Sturdevant's Art and Science of Operative Dentistry, 7th Edition.