This Privat-Docent thesis investigates how validated three-dimensional (3D) digital dental cast analysis can enhance the accuracy, reproducibility, and clinical relevance of orthodontic assessment. Building upon a previously validated landmark-based 3D measurement protocol, capable of reliably quantifying torque, tip, rotation, and transverse dimensions without additional radiation exposure, the work positions digital dental models as a central, data-rich resource for contemporary orthodontics. The overarching objective is to reduce the discrepancy between virtual planning—often informed by software assumptions—and the biological realities observed in treated patients.

Study 1 evaluates the predictive accuracy of clear aligner therapy by comparing planned movements in ClinCheck with the achieved outcomes in adults treated with Invisalign Lite. Systematic under-expression of angular movements was observed, particularly for torque, tip, and rotation in maxillary lateral incisors, canines, premolars, and molars. Transverse changes were substantially more predictable. These findings underscore the need for evidence-based overcorrection strategies and highlight inherent limitations of current aligner planning algorithms.

Study 2 examines the dentoalveolar effects of cervical headgear in growing Class II patients within a randomized controlled framework. Objective compliance was recorded through force- and temperature-sensitive modules, and dental changes were quantified with the 3D protocol. Headgear produced significant distalization and transverse modifications, yet treatment efficacy showed a clear dose–response relationship with wear time. The integration of objective compliance metrics with precise 3D dental measurements illustrates how behavioral factors critically mediate appliance performance.

Study 3 assesses longitudinal changes in clinical crown height from ages 8 to 18 using digitized casts from the Michigan Growth Study. All investigated teeth—maxillary and mandibular central incisors and first molars—exhibited significant increases in clinical crown height throughout adolescence, reflecting ongoing secondary eruption and apical migration of the gingival margin. These results highlight the dynamic nature of dentogingival aesthetics and caution against premature aesthetic crown-lengthening procedures in young patients.

Collectively, the three studies demonstrate that routine digital impressions, when analyzed through a validated 3D framework, provide robust quantitative insights into treatment predictability, appliance effectiveness, and growth-related changes. The thesis advocates for a data-driven orthodontic paradigm in which digital planning is continuously confronted with objective clinical evidence, and in which future integration of artificial intelligence may further automate measurement, improve prediction of treatment outcomes, and enhance the fidelity of virtual treatment simulations.