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Korean J Orthod
Copyright © The Korean Association of Orthodontists.
Yinyin Zhang a, b; Liwei Xiao a, c, d; Xinyue Cao a; Yunting Zeng a, c, d
a Department of Stomatology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
b Department of Stomatology, The First People's Hospital of Huzhou, Huzhou, Zhejiang, China
c Hunan Provincial Engineering Research Center of Digital Oral and Maxillofacial Defect Repair, Changsha, China
d Hunan Provincial Clinical Research Center for Oral Diseases, Changsha, China
Correspondence to:Yunting Zeng, Department of Orthodontics, Medical Center of Stomatology, The Second Xiangya Hospital, Central South University, 126 Shaoshan North Road, Furong District, Changsha 410011, P. R. China
Telephone number: +86-158-7421-9087
E-mail address: zengyunting@csu.edu.cn
Objective: This study aims to evaluate using a stainless-steel fixed retainer for postorthodontic retention in patients with labiolingual alveolar bone resorption in the mandibular anterior segment. Methods: Three mandibular anterior segment models (without, with labial or lingual alveolar bone resorption) with 0.5 mm diameter retainers bonded on all teeth were constructed. Two occlusion schemes were simulated: a 285.3 N force applied to four mandibular incisors (incisor biting) and a 93 N force applied to the left canine (laterotrusion). Tooth displacement and stress distribution on the periodontal ligament (PDL), retainer, and composite were evaluated. Results: Compared to no resorption, labial bone resorption significantly increased tooth displacement and PDL stress concentration of central incisors during incisor biting, whereas lingual resorption had a greater effect on the guiding canine during laterotrusion. The retainers were susceptible to stress concentrations in the resin-uncovered area, the mesial region of lateral incisors under incisor biting, and the mesial region of the guiding canine under laterotrusion. For the composite, the composite–retainer interface was prone to stress concentrations, especially mesial or distal extremes of the adhesive composite of incisors. Conclusions: A 0.5 mm diameter stainless-steel lingual retainer bonded on all teeth is a clinically acceptable retention procedure for patients with lingual bone resorption in the lower anterior region but should be used more cautiously for labial bone resorption patients as it exposes lower central incisors to a greater risk. Excessive stress on the retainer and composite from occlusion force may lead to unwanted tooth movement, necessitating closer monitoring.
Keywords: FEA, Retention and stability, Labiolingual bone resorption, Fixed retainer
Korean J Orthod
First Published Date December 16, 2024
Copyright © The Korean Association of Orthodontists.
Yinyin Zhang a, b; Liwei Xiao a, c, d; Xinyue Cao a; Yunting Zeng a, c, d
a Department of Stomatology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
b Department of Stomatology, The First People's Hospital of Huzhou, Huzhou, Zhejiang, China
c Hunan Provincial Engineering Research Center of Digital Oral and Maxillofacial Defect Repair, Changsha, China
d Hunan Provincial Clinical Research Center for Oral Diseases, Changsha, China
Correspondence to:Yunting Zeng, Department of Orthodontics, Medical Center of Stomatology, The Second Xiangya Hospital, Central South University, 126 Shaoshan North Road, Furong District, Changsha 410011, P. R. China
Telephone number: +86-158-7421-9087
E-mail address: zengyunting@csu.edu.cn
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Objective: This study aims to evaluate using a stainless-steel fixed retainer for postorthodontic retention in patients with labiolingual alveolar bone resorption in the mandibular anterior segment. Methods: Three mandibular anterior segment models (without, with labial or lingual alveolar bone resorption) with 0.5 mm diameter retainers bonded on all teeth were constructed. Two occlusion schemes were simulated: a 285.3 N force applied to four mandibular incisors (incisor biting) and a 93 N force applied to the left canine (laterotrusion). Tooth displacement and stress distribution on the periodontal ligament (PDL), retainer, and composite were evaluated. Results: Compared to no resorption, labial bone resorption significantly increased tooth displacement and PDL stress concentration of central incisors during incisor biting, whereas lingual resorption had a greater effect on the guiding canine during laterotrusion. The retainers were susceptible to stress concentrations in the resin-uncovered area, the mesial region of lateral incisors under incisor biting, and the mesial region of the guiding canine under laterotrusion. For the composite, the composite–retainer interface was prone to stress concentrations, especially mesial or distal extremes of the adhesive composite of incisors. Conclusions: A 0.5 mm diameter stainless-steel lingual retainer bonded on all teeth is a clinically acceptable retention procedure for patients with lingual bone resorption in the lower anterior region but should be used more cautiously for labial bone resorption patients as it exposes lower central incisors to a greater risk. Excessive stress on the retainer and composite from occlusion force may lead to unwanted tooth movement, necessitating closer monitoring.
Keywords: FEA, Retention and stability, Labiolingual bone resorption, Fixed retainer
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