{"title":"下颌阻生第三磨牙拔牙时牙根断裂阈值及周围组织应力分析。","authors":"Zhengfen Li, Yijun Liu, Jiangling Sun, Meiyan Rong, Cheng Niu, Xubo Duan, Wei Yang, Mingkun Liu","doi":"10.1186/s12903-025-06744-2","DOIUrl":null,"url":null,"abstract":"<p><strong>Background: </strong>This biomechanical study aimed to investigate root fracture thresholds and stress distributions in surrounding tissue while extracting three types of impacted mandibular third molars (horizontal, vertical, and mesioangular impactions) under varying dental elevator loading conditions.</p><p><strong>Methods: </strong>Mechanical tensile testing was conducted to determine the anisotropic properties and maximum fracture load of extracted teeth. Three-dimensional finite element models, reconstructed from cone beam computed tomography (CBCT) data, were used to simulate elevator-assisted extraction processes. Stress distributions and root fracture thresholds were analyzed under three loading modes (wedge, lever, and rotational force) at different abduction angles.</p><p><strong>Results: </strong>Horizontal impactions demonstrated the lowest fracture resistance under lever forces (38.7-50.3 N), while vertical impactions exhibited the highest thresholds (110.3-342.2 N). Wedge forces showed angular dependence inversely correlated with fracture thresholds for horizontal impactions (76-174 N). Rotational moments maintained relatively stable thresholds across all impaction types (X-axis: 21-32 N·m, Y-axis: 20-40.8 N·m, Z-axis: 16.3-33.5 N·m). Surrounding tissue stress decreased with increasing abduction angles under lever and wedge forces (p < 0.05) but no significant directional correlation was observed under rotational moments.</p><p><strong>Conclusions: </strong>Dentin anisotropy and elevator angulation significantly influence fracture mechanics. Clinical protocols should prioritize lever forces for vertical impactions (safety margin > 100 N), with wedge and rotational force more effective for horizontal impaction. The findings provide an important theoretical basis for oral surgeons in extracting impacted third molars and for the subsequent development of surgical path planning and intelligent reasoning systems by the research group.</p>","PeriodicalId":9072,"journal":{"name":"BMC Oral Health","volume":"25 1","pages":"1573"},"PeriodicalIF":3.1000,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12509397/pdf/","citationCount":"0","resultStr":"{\"title\":\"Fracture threshold of tooth roots and stress analysis of surrounding tissue during the extraction of impacted mandibular third molars using dental elevators.\",\"authors\":\"Zhengfen Li, Yijun Liu, Jiangling Sun, Meiyan Rong, Cheng Niu, Xubo Duan, Wei Yang, Mingkun Liu\",\"doi\":\"10.1186/s12903-025-06744-2\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p><strong>Background: </strong>This biomechanical study aimed to investigate root fracture thresholds and stress distributions in surrounding tissue while extracting three types of impacted mandibular third molars (horizontal, vertical, and mesioangular impactions) under varying dental elevator loading conditions.</p><p><strong>Methods: </strong>Mechanical tensile testing was conducted to determine the anisotropic properties and maximum fracture load of extracted teeth. Three-dimensional finite element models, reconstructed from cone beam computed tomography (CBCT) data, were used to simulate elevator-assisted extraction processes. Stress distributions and root fracture thresholds were analyzed under three loading modes (wedge, lever, and rotational force) at different abduction angles.</p><p><strong>Results: </strong>Horizontal impactions demonstrated the lowest fracture resistance under lever forces (38.7-50.3 N), while vertical impactions exhibited the highest thresholds (110.3-342.2 N). Wedge forces showed angular dependence inversely correlated with fracture thresholds for horizontal impactions (76-174 N). Rotational moments maintained relatively stable thresholds across all impaction types (X-axis: 21-32 N·m, Y-axis: 20-40.8 N·m, Z-axis: 16.3-33.5 N·m). Surrounding tissue stress decreased with increasing abduction angles under lever and wedge forces (p < 0.05) but no significant directional correlation was observed under rotational moments.</p><p><strong>Conclusions: </strong>Dentin anisotropy and elevator angulation significantly influence fracture mechanics. Clinical protocols should prioritize lever forces for vertical impactions (safety margin > 100 N), with wedge and rotational force more effective for horizontal impaction. The findings provide an important theoretical basis for oral surgeons in extracting impacted third molars and for the subsequent development of surgical path planning and intelligent reasoning systems by the research group.</p>\",\"PeriodicalId\":9072,\"journal\":{\"name\":\"BMC Oral Health\",\"volume\":\"25 1\",\"pages\":\"1573\"},\"PeriodicalIF\":3.1000,\"publicationDate\":\"2025-10-08\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12509397/pdf/\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"BMC Oral Health\",\"FirstCategoryId\":\"3\",\"ListUrlMain\":\"https://doi.org/10.1186/s12903-025-06744-2\",\"RegionNum\":2,\"RegionCategory\":\"医学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"DENTISTRY, ORAL SURGERY & MEDICINE\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"BMC Oral Health","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1186/s12903-025-06744-2","RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"DENTISTRY, ORAL SURGERY & MEDICINE","Score":null,"Total":0}
Fracture threshold of tooth roots and stress analysis of surrounding tissue during the extraction of impacted mandibular third molars using dental elevators.
Background: This biomechanical study aimed to investigate root fracture thresholds and stress distributions in surrounding tissue while extracting three types of impacted mandibular third molars (horizontal, vertical, and mesioangular impactions) under varying dental elevator loading conditions.
Methods: Mechanical tensile testing was conducted to determine the anisotropic properties and maximum fracture load of extracted teeth. Three-dimensional finite element models, reconstructed from cone beam computed tomography (CBCT) data, were used to simulate elevator-assisted extraction processes. Stress distributions and root fracture thresholds were analyzed under three loading modes (wedge, lever, and rotational force) at different abduction angles.
Results: Horizontal impactions demonstrated the lowest fracture resistance under lever forces (38.7-50.3 N), while vertical impactions exhibited the highest thresholds (110.3-342.2 N). Wedge forces showed angular dependence inversely correlated with fracture thresholds for horizontal impactions (76-174 N). Rotational moments maintained relatively stable thresholds across all impaction types (X-axis: 21-32 N·m, Y-axis: 20-40.8 N·m, Z-axis: 16.3-33.5 N·m). Surrounding tissue stress decreased with increasing abduction angles under lever and wedge forces (p < 0.05) but no significant directional correlation was observed under rotational moments.
Conclusions: Dentin anisotropy and elevator angulation significantly influence fracture mechanics. Clinical protocols should prioritize lever forces for vertical impactions (safety margin > 100 N), with wedge and rotational force more effective for horizontal impaction. The findings provide an important theoretical basis for oral surgeons in extracting impacted third molars and for the subsequent development of surgical path planning and intelligent reasoning systems by the research group.
期刊介绍：
BMC Oral Health is an open access, peer-reviewed journal that considers articles on all aspects of the prevention, diagnosis and management of disorders of the mouth, teeth and gums, as well as related molecular genetics, pathophysiology, and epidemiology.
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号
