Yellowness Correlates with Stiffness in Aging Human Dentin

Age-related yellowing and mechanical deterioration of teeth are well recognized in clinical dentistry, yet their interrelationship and underlying mechanisms remain incompletely understood. This study aimed to clarify the associations among dentin color, mechanical properties, and advanced glycation end-product (AGE) accumulation in aging human dentin.

In this cross-sectional study, buccal-lingual cross sections of extracted human premolars and molars obtained from donors aged 16 to 77 y were analyzed. Dentin was subdivided into 4 anatomical regions (outer/inner crown and outer/inner root). Yellowness (b*) was quantified from optical microscopy images, and Young's modulus was determined using position-resolved nanoindentation. Pentosidine concentration was quantified by high-performance liquid chromatography as a surrogate marker of AGE accumulation. All parameters were measured within the same specimens, enabling spatially resolved correlation analyses across anatomical regions.

Yellowness, Young's modulus, and pentosidine concentration increased significantly with age in all dentin regions. Pentosidine concentration showed a positive correlation with yellowness, indicating an association between AGE accumulation and dentin discoloration. In contrast, no consistent correlation was observed between pentosidine concentration and Young's modulus. Notably, a significant positive correlation was identified between yellowness and Young's modulus in most dentin regions, except for the outer crown, suggesting that color changes more closely reflect mechanical alterations than AGE accumulation alone. Regional differences were observed, with more pronounced age-related changes in the root dentin than in the crown.

Dentin yellowness is more strongly associated with age-related mechanical changes than with AGE accumulation, as assessed by pentosidine. These findings indicate that tooth color may serve as a practical, noninvasive indicator of age-related dentin mechanical changes, providing clinically relevant insight into tooth aging beyond esthetic considerations.Knowledge Transfer Statement:Aging-related yellowing of teeth is often regarded as a cosmetic issue, but its relationship to tooth structural integrity has remained unclear. This study demonstrates that dentin yellowness is significantly correlated with increased stiffness in aging human dentin and is more closely associated with stiffness than pentosidine accumulation alone. Tooth color may therefore serve as a simple, noninvasive indicator of age-related dentin mechanical changes, supporting earlier clinical assessment and preventive strategies to prolong tooth longevity in older populations.