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Fully digital pneumatic gingival-retraction scanning technique: from methodology development to clinical validation
Xinkai Xu1, Sukun Tian2, Meizi Zhang2
1Center of Digital Dentistry, Department of Prosthodontics, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices & NHC Key Laboratory of Digital Stomatology & Beijing Key Laboratory of Digital Stomatology & Key Laboratory of Digital Stomatology, Chinese Academy of Medical Sciences, Beijing 100081, China; Institute of Medical Technology, Peking University Health Science Center, Beijing 100191, China.
Objective:
To address clinical issues such as soft tissue trauma and patient discomfort and technical challenges such as inaccuracies in digital impression matching that are associated with traditional cord methods of gingival retraction.
Methods:
This study introduced a novel pneumatic gingival-retraction scanning (PGR-S) technique inspired by clinical observations of using a three-way syringe airflow to displace free gingiva non-invasively and painlessly. This innovation was achieved through two key technological advancements: (1) creating a scanning-airflow integrated system and (2) developing a polar coordinate-based point cloud stitching algorithm that utilizes dynamic normal distance discrimination. A prospective, self-controlled clinical trial (ChiCTR2500098214) including 60 participants was conducted to evaluate the effectiveness and patient experience of PGR-S compared to that of the gingival cord-retained scanning (GC-S) and the traditional gingival cord-removed silicone impression (GC-I) methods. Additionally, operation times for PGR and GC procedures were compared.
Results:
Statistical analysis showed significant main effects of the technique type, tooth position, and buccal/lingual location on the effectiveness of gingival retraction (P < 0.05). PGR-S had better performance with a mean of 302.9 ± 124.9 µm. All subjective evaluation metrics-comfort, pain, nausea, and dryness-differed significantly among the PGR-S, GC-S, and GC-I groups (P < 0.001). The PGR-S group reported increased comfort, but also experienced greater tissue dryness. Additionally, the operating time for PGR (70.48 ± 17.90 s) was significantly shorter than that for the GC techniques (194.78 ± 42.81 s P < 0.001).
Conclusion:
Within the limitations of this study, the novel PGR-S technique demonstrated effective gingival retraction, shortened operating time, and improved patient comfort compared to traditional methods.
Clinical Significance:
This study introduces a new clinical method for minimally invasive gingival retraction combined with intraoral scanning, aiming to improve patient outcomes and comfort.
