中国实用口腔科杂志 ›› 2025, Vol. 18 ›› Issue (3): 294-299.DOI: 10.19538/j.kq.2025.03.007

• 论著 • 上一篇    下一篇

改良式牙冠延长术和肩领高度对斜折残根抗折性能的影响研究

王晓雪a,吴素然a,张    晓b,张立亚c   

  1. 河北医科大学口腔医学院·口腔医院a 口腔修复科,b 口腔颌面外科,c 牙体牙髓科,河北省口腔医学重点实验室,河北省口腔疾病临床医学研究中心,河北 石家庄 050017
  • 出版日期:2025-05-30 发布日期:2025-05-30
  • 基金资助:
    河北省卫生健康委员会医学科学研究课题计划项目(20221471)

  • Online:2025-05-30 Published:2025-05-30

摘要: 目的    研究改良式牙冠延长术和肩领高度对纤维桩核冠修复后下颌第一前磨牙斜折残根抗折性能的影响。方法    选取2024年4—7月在河北医科大学口腔医学院·口腔医院口腔颌面外科拔除的下颌第一前磨牙40颗(均为单根管)。常规根管治疗后,在舌侧釉牙骨质界上3.0 mm处截断牙冠,自舌侧斜向颊侧釉牙骨质界上1.0 mm处切割,制成舌颊向斜折残根模型。将其随机分为5组(A ~ E组),每组8个。A组:对照组,设计成舌侧2.0 mm、颊侧0 mm高的半包绕型牙本质肩领;B组:模拟改良式牙冠延长术,在残根颈部设计舌侧2.0 mm、颊侧1.0 mm高的牙本质肩领;C组、D组、E组:模拟改良式牙冠延长术,在残根颈部分别设计2.0、3.0、4.0 mm高的全包绕型牙本质肩领。经预成玻璃纤维桩加树脂核及钴铬金属全冠修复后,自凝树脂块包埋试件,完成后的A ~ E组试件临床冠根比值(C/R)分别为0.75、0.83、0.91、1.10、1.33;包埋完成的试件置于万能试验机上加载(加载方向与牙长轴呈150°)直至断裂。记录试件折裂载荷及折裂模式。结果    A ~ E组试件的折裂载荷依次为(1.45 ± 0.10)、(1.63 ± 0.07)、(1.67 ± 0.09)、(0.95 ± 0.12)、(0.69 ± 0.18)kN,各组折裂载荷比较,差异有统计学意义(F = 112.047,P < 0.001)。进一步组间两两比较发现,仅B组与C组之间比较差异无统计学意义(q = 0.494,P = 0.957)。各组折裂模式中,仅D组和E组有2个试件断面位于根颈1/3以下,其余组别断面均位于根颈1/3以上或出现桩核折裂、脱落;各组间试件折裂模式比较,差异无统计学意义(χ2 = 6.321,P = 0.642)。结论    在模拟分析改良式牙冠延长术和肩领高度对纤维桩核冠修复后下颌第一前磨牙斜折残根抗折性能的影响时,牙本质肩领高度的不同会显著影响桩核冠修复后该类残根的抗力,在残根颈部制备1.0 ~ 2.0 mm高度的全包绕牙本质肩领且冠根比小于1时,才能保证牙体良好的抗折性能。

关键词: 改良式牙冠延长术, 牙本质肩领, 纤维桩核冠, 残根, 抗折性能

Abstract: Objective    To study the effects of modified crown lengthening procedure combined with ferrule height on the fracture resistance of mandibular first premolar with oblique fractures restored with fiber post and core crown. Methods    Totally forty mandibular first premolars(all single-root canals)extracted at the Department of Oral and Maxillofacial Surgery,School and Hospital of Stomatology,Hebei Medical University from April to July 2024 were selected. Following conventional root canal treatment,the crowns were severed at a height of 3.0 mm above the lingual enamel-cementum junction and subsequently cut from the lingual section to the buccal at 1.0 mm above the buccal enamel-cementum junction to create the lingual-buccal oblique fractured root models. They were randomly divided into 5 groups(Groups A to E),with 8 in each group. Group A:the control group,designed with a half-wrapped dentin ferrule measuring 2.0 mm on the lingual side and 0 mm on the buccal side;Group B:simulated modified crown lengthening procedure,designed with a dentin ferrule measuring 2.0 mm on the lingual side and 1.0 mm on the the buccal side;Groups C,D and E:simulated modified crown lengthening procedure,designed with a full-wrapped dentin ferrule measuring 2.0 mm,3.0 mm and 4.0 mm respectively at the residual root neck. After restoration with preformed glass fiber posts,resin cores and cobalt-chromium metal full crown,the specimens were embedded in self-curing resin blocks. The clinical crown-root ratios(C/R)of the completed Groups A to E were 0.75,0.83,0.91,1.10 and 1.33,respectively. The embedded specimens were placed on a universal testing machine and loaded(the loading direction was at an angle of 150° to the long axis of the tooth)until fracture. The fracture load values and fracture mode of the specimens were recorded. Results    The fracture loads of the specimens in Groups A to E were(1.45 ± 0.10)kN,(1.63 ± 0.07)kN,(1.67 ± 0.09)kN,(0.95 ± 0.12)kN and(0.69 ± 0.18)kN,respectively. There was a statistically significant difference in the fracture loads among the groups(F = 112.047,P < 0.001). Further pairwise comparisons between groups revealed that there was no statistically significant difference between Group B and Group C(q = 0.494,P = 0.957),but there were statistically significant differences among the other groups(all P < 0.05). Among the fracture mode of each group,only 2 specimens in Groups D and E had fracture surfaces below the cervical one-third of the root,while the fracture surfaces of the other groups were above the cervical one-third,or there were fractures and detachments of the post-core. There was no significant difference in the fracture mode among all groups(χ2 = 6.321,P = 0.642). Conclusion    In simulating the effects of modified crown lengthening procedure combined with ferrule height on the fracture resistance of mandibular first premolars following fiber post-core crown restoration,it is found that variations in dentine ferrule height significantly influence the resistance of these residual roots after restoration. Specifically,when a fully wrapped dentine ferrule measuring 1.0 - 2.0 mm is prepared at the residual root neck and the crown-to-root ratio remains below 1,optimal fracture resistance of the teeth can be ensured.

Key words: modified crown lengthening procedure, dentin ferrule, fiber post-core crown, residual roots, fracture resistance