Enhancing color and comfort: A preliminary clinical study on the Dahl approach using 3D printed noninvasive restorations

STATEMENT OF PROBLEM: Clinical evidence regarding the long-term (up to 24 months) color stability of 3-dimensional printed (3D), noninvasive restorations is scarce, particularly when used to implement the Dahl concept. Whether these restorations meet esthetic requirements over time and how potential discoloration affects patient-reported outcomes remains unclear. PURPOSE: The purpose of this clinical pilot study was to provide initial clinical evidence on the performance of 3D printed, noninvasive restorations used for the implementation of the Dahl concept, with a particular focus on their long-term color stability and their impact on patient-reported oral health-related quality of life. MATERIAL AND METHODS: Five participants with localized tooth wear were included in the study, each treated with 3D printed, noninvasive restorations fabricated from a computer-aided design and computer-aided manufacturing (CAD-CAM) ceramic-filled hybrid composite material. Color change measurements were performed using a spectrophotometer to record L* (lightness), a* (red-green), and b* (blue-yellow) values at 6, 12, and 24 months. Patient-related quality of life was evaluated using the Oral Health Impact Profile (OHIP) questionnaire. RESULTS: Four participants with 24 restorations were documented. All restorations remained clinically in complete function over the 24-month follow-up. Spectrophotometric analysis revealed progressive color changes over time, with mean ΔE values exceeding commonly accepted perceptibility (ΔE=3.7) and acceptability (ΔE=5.5) thresholds at 12 months (5.84 ±2.59) and 24 months (11.27 ±5.85). Despite the observed discoloration, patient-reported oral health-related quality of life improved after treatment and remained stable throughout the observation period, with high ratings for function, comfort, and esthetics. CONCLUSIONS: Although 3D printed, noninvasive restorations improved patient-related oral health quality of life, their unfavorable long-term color stability limits their use to long-term interim restorations as advocated by the Dahl concept.