Retention and patient‐reported outcomes of low‐profile attachment system for mandibular overdentures: A crossover clinical trial comparing 3D‐printed and conventional dentures

PURPOSE: This crossover clinical trial aimed to evaluate and compare the retention performance, attachment wear, and patient‑reported outcomes between a new low-profile attachment system (EMI, JDEvolution) and a conventional locator attachment system (Zest Dental Solutions) used to retain 3D-printed and conventionally fabricated implant-retained overdentures. MATERIALS AND METHODS: Twenty edentulous participants were randomly allocated to two groups according to attachment system: the EMI group and the locator group. Each participant received two overdentures, one conventionally fabricated and one 3D‑printed, in a crossover design. Each overdenture was provided with a set of attachments and was evaluated for 9 months. Clinical assessments included retention measurement and attachment component wear. Visual analog scale (VAS) scores were used to measure patient‑reported outcomes. Qualitative visual and scanning electron microscopy (SEM) evaluation of attachment‑component wear was performed. Data were collected at baseline, 3, 6, and 9 months. ANOVA with post‑hoc tests were used for collected data analysis (α = 0.05). RESULTS: Both attachment systems showed a significant reduction in retention over time compared with baseline (p < 0.001). The EMI attachment system showed higher initial retention values but a sharp significant decline over time (p < 0.001), recording the lowest retention values at 9 months (4.1 ±0.4 N and 3.9 ±0.6 N) for conventional and 3D-printed dentures, respectively. The Locator attachment system showed minimal and stable reduction, with the lowest retention at 9 months (8.7 ± 1.4 N). Both conventional and 3D‑printed dentures exhibited the same pattern of retention loss. Qualitative analyses reported that both attachment systems showed variation in component deteriorations; however, the EMI group exhibited progressive component degradation with frequent need for replacement. VAS scores reflect the patient's satisfaction with Locator over time (p = 0.287). Although VAS scores declined significantly in the EMI group (p < 0.001) at the 9‑month follow‑up, the reduction was most pronounced when the EMI attachment was combined with the 3D‑printed denture, which demonstrated the steepest deterioration across all evaluated domains. CONCLUSION: The retention of both attachment systems decreased over time, with a sharp retention loss with the EMI attachment at 9 months. Additionally, the EMI attachment showed noticeable component wear and deterioration compared with Locator. Denture type had no effect on the retention loss. EMI attachment showed a clear decline in patient satisfaction by the end of the follow‑up period, whereas Locator maintained consistently higher satisfaction over time. The reduced 9‑month performance of EMI attachment and its frequent maintenance requirements indicate that it should be selected cautiously until further long‑term evidence supports its durability.