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Background <p>This study compared site-specific dimensional changes after intraoral aging between direct-printed retainers (DPRs) and thermoformed retainers (TFRs), focusing on changes in occlusal contact areas (OCAs) and occlusal force distribution (OFD) across different intra-arch tooth locations and surfaces, reflecting the patient’s dentoskeletal pattern.</p> Methodology <p>Of 26 participants, 22 (12 males, 10 females; mean age 22.5 ± 4.2 years) were included and assessed for cephalometric skeletal patterns. DPRs (maxillary and mandibular) were fabricated from oral scans obtained on the day of debonding. TFR pairs were fabricated on printed master models using the same scan data. Before delivery (<i>T0</i>), maxillary DPRs and TFRs (<i>n</i> = 22 each) fitted on the master model were scanned using micro-computed tomography (micro-CT), and relative occlusal force distribution was quantitatively measured using a T-Scan device by dividing the dentition into five regions during occlusion with retainers in place. After two weeks of full-time intraoral use following the experimental protocol (<i>T1</i>), maxillary DPRs and TFRs were retrieved for the second assessment. Micro-CT gap widths were measured at five surface points around eight teeth for a total of 88 samples and analyzed for inter-retainer comparison and correlation with occlusal and skeletal variables using statistical analysis.</p> Result <p>Unused DPRs revealed greater gap widths than TFRs at incisal edges and cusp tips of all tested teeth (<i>P</i>&lt;.001). The retrieved TFRs showed an overall gap increase, especially in the gingival areas, along with an increase in the OCA (<i>P</i>&lt;.05), in relation to the patient’s mandibular plane angle (MPA) (<i>P</i>&lt;.05). The retrieved DPRs exhibited gap decreases in the posterior teeth (<i>P</i>&lt;.001) and gap increases in the anterior teeth, especially in the linguogingival area (<i>P</i>&lt;.05), compared to the initial OCA value (<i>P</i>&lt;.01), with no correlation with the patient’s skeletal pattern. The OFD revealed no relationship with gap changes, regardless of the tooth location and surface.</p> Conclusion <p>Within clinically acceptable ranges of gap discrepancy, the DPRs exhibited site-specific dimensional behavior after intraoral use representing enhanced retainer fit in the posterior teeth and worsened fit in the anterior teeth, in relation to the initial OCA, in contrast with the TFRs showing overall gap increases with higher susceptibility to patient’s occlusal and skeletal patterns.</p>

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Dimensional behaviors of direct-printed versus thermoformed clear retainers in relation to changes of inter-piece occlusal contact distribution measured by T-scan after intraoral aging: a prospective clinical study

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年3月17日

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  • Hwarang Jeong,
  • Min-Ji Jeon,
  • Kun-Woo Park,
  • Tamara Mahmalji,
  • Jin-Young Choi,
  • Su-Jung Kim

摘要

Background

This study compared site-specific dimensional changes after intraoral aging between direct-printed retainers (DPRs) and thermoformed retainers (TFRs), focusing on changes in occlusal contact areas (OCAs) and occlusal force distribution (OFD) across different intra-arch tooth locations and surfaces, reflecting the patient’s dentoskeletal pattern.

Methodology

Of 26 participants, 22 (12 males, 10 females; mean age 22.5 ± 4.2 years) were included and assessed for cephalometric skeletal patterns. DPRs (maxillary and mandibular) were fabricated from oral scans obtained on the day of debonding. TFR pairs were fabricated on printed master models using the same scan data. Before delivery (T0), maxillary DPRs and TFRs (n = 22 each) fitted on the master model were scanned using micro-computed tomography (micro-CT), and relative occlusal force distribution was quantitatively measured using a T-Scan device by dividing the dentition into five regions during occlusion with retainers in place. After two weeks of full-time intraoral use following the experimental protocol (T1), maxillary DPRs and TFRs were retrieved for the second assessment. Micro-CT gap widths were measured at five surface points around eight teeth for a total of 88 samples and analyzed for inter-retainer comparison and correlation with occlusal and skeletal variables using statistical analysis.

Result

Unused DPRs revealed greater gap widths than TFRs at incisal edges and cusp tips of all tested teeth (P<.001). The retrieved TFRs showed an overall gap increase, especially in the gingival areas, along with an increase in the OCA (P<.05), in relation to the patient’s mandibular plane angle (MPA) (P<.05). The retrieved DPRs exhibited gap decreases in the posterior teeth (P<.001) and gap increases in the anterior teeth, especially in the linguogingival area (P<.05), compared to the initial OCA value (P<.01), with no correlation with the patient’s skeletal pattern. The OFD revealed no relationship with gap changes, regardless of the tooth location and surface.

Conclusion

Within clinically acceptable ranges of gap discrepancy, the DPRs exhibited site-specific dimensional behavior after intraoral use representing enhanced retainer fit in the posterior teeth and worsened fit in the anterior teeth, in relation to the initial OCA, in contrast with the TFRs showing overall gap increases with higher susceptibility to patient’s occlusal and skeletal patterns.