不同形式高嵌体修复上颌前磨牙腭尖缺损的抗折性能研究

A study of the fracture resistance of different designed onlays for maxillary premolar with palatal cusp defect

目的:对比不同形式高嵌体修复上颌前磨牙腭尖缺损后的抗折性能。方法:收集完整上颌前磨牙50颗,随机分为5组(n=10),A~D组制作腭尖缺损模型,其中A、B组为露髓组,C、D组为未露髓组,E组为完整离体牙。缺损组采用不同形式嵌体修复,A组:树脂核+高嵌体;B组:预成纤维桩+树脂核+高嵌体;C组:高嵌体,只恢复腭尖;D组:高嵌体,覆盖颊尖。试件经人工老化后在万能力学试验机上施静态载荷至修复体折断、脱落,记录断裂载荷及断裂模式,结果进行单因素方差分析。结果:A~E组的最大折裂载荷分别为(2244.42±401.1)、(2253.14±273.88)、(1236.72±326.46)、(1819.7±364.53)、(1024.92±304.11)N。D组抗折性能优于C组(P<0.05)。C组发生2例不可修复性折裂,其余组未见不可修复性折裂的发生。结论:当缺损累及牙髓时,选择树脂核或预成纤维桩树脂核高嵌体修复具有相似的抗折性能;当缺损未累及牙髓时,优先选择覆盖颊尖高嵌体。

Objective:To compare the fracture resistance among different designed onlays for maxillary premolar with palatal cusp defect.Methods:50 maxillary premolars extracted for orthodontics were collected and randomly divided into 5 groups(n=10).The palatal cusp defect model was prepared on each of the teeth and the defects were repaired by composite resin core+onlay(Group A),prefabricated glass fiber post+composite resin core+onlay(Group B),lithium disilicate glass-ceramic onlay(Group C),lithium disilicate glass-ceramic onlay with buccal cusps and palatal apical restored(Group D),respectively.Intact teeth(Group E)were used as the controls.All specimens were subjected to thermocycling(5000 cycles,5~55℃)and water aging followed by the immediate test of fracture resistance.The specimens were loaded at a loading direction of 20°to the tooth axis and crosshead speed of 1.0 mm/min.Until the restoration broke off,fracture loads and modes of failure were recorded,and results were treated as on,E-way ANOWA,and adhesive failure modes were observed in a stereomicroscope.Results:The maximum load(N)of A,B,C,D and E was(2244.42±401.1),(2253.14±273.88),(1236.72±326.46),(1819.7±364.53)and(1024.92±304.11)N respectively.Between group C and D(P<0.05).By observing the fracture pattern,it was found that two cases of unfavorable failure occurred in group C,while no unfavorable failure was observed in other groups.Conclusion:When the pulp of the defect of palatal cusp of maxillary premolar was involved,onlay with composite resin core and prefabricated glass fiber post+composite resin core have similar fracture resistance.When the defect doesn't involve the pulp,the higer fracture resistance can be obtained by covering the onlay with buccal cusps and palatal cusps restored.