Journal of prosthodontic research · 2026
Effect of zirconia tube reinforcement on fracture resistance and microleakage of endodontically treated premolars with flared root canals under cyclic loading.
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Yu Mingchen, Komada Wataru, Oishi Shinya, Kondo Daiki, Fueki Kenji
Аннотация
PURPOSE: We evaluated the effects of zirconia tubes on fracture resistance and microleakage of endodontically treated premolars with flared root canals under cyclic loading.
METHODS: Sixty-four bovine mandibular incisors were prepared to simulate human premolars and randomly assigned to four core build-up groups (n = 16 per group): composite resin core only (RC), glass-fiber post (FC), zirconia tube (ZC), and zirconia tube with glass-fiber post (ZFC). After crown fabrication and cementation, specimens underwent cyclic loading (10,000 cycles, 50 N, 2 Hz). In each group, eight specimens (n = 8) were evaluated for fracture resistance under 45 degree oblique loading, and eight (n = 8) were evaluated for microleakage using micro-computed tomography (micro-CT) after silver nitrate immersion.
RESULTS: ZC and ZFC exhibited significantly higher fracture resistance than RC (P = 0.004, 0.022) and FC (P = 0.001, 0.047), with no difference between RC and FC or between ZC and ZFC. Microleakage was significantly lower in ZC and ZFC than in RC and FC (all P < 0.001). Leakage in zirconia tube groups was largely confined to the cervical area, whereas RC and FC showed penetration into the root canal. All specimens in each group exhibited fractures extending below the simulated alveolar bone level, corresponding to unfavorable fracture modes.
CONCLUSIONS: Zirconia tubes enhanced fracture resistance and reduced microleakage under cyclic loading in endodontically treated premolars. Foundation restorations using zirconia tubes may be a reliable reinforcement option for structurally weakened roots. Further clinical and long-term studies are required to confirm these findings.
METHODS: Sixty-four bovine mandibular incisors were prepared to simulate human premolars and randomly assigned to four core build-up groups (n = 16 per group): composite resin core only (RC), glass-fiber post (FC), zirconia tube (ZC), and zirconia tube with glass-fiber post (ZFC). After crown fabrication and cementation, specimens underwent cyclic loading (10,000 cycles, 50 N, 2 Hz). In each group, eight specimens (n = 8) were evaluated for fracture resistance under 45 degree oblique loading, and eight (n = 8) were evaluated for microleakage using micro-computed tomography (micro-CT) after silver nitrate immersion.
RESULTS: ZC and ZFC exhibited significantly higher fracture resistance than RC (P = 0.004, 0.022) and FC (P = 0.001, 0.047), with no difference between RC and FC or between ZC and ZFC. Microleakage was significantly lower in ZC and ZFC than in RC and FC (all P < 0.001). Leakage in zirconia tube groups was largely confined to the cervical area, whereas RC and FC showed penetration into the root canal. All specimens in each group exhibited fractures extending below the simulated alveolar bone level, corresponding to unfavorable fracture modes.
CONCLUSIONS: Zirconia tubes enhanced fracture resistance and reduced microleakage under cyclic loading in endodontically treated premolars. Foundation restorations using zirconia tubes may be a reliable reinforcement option for structurally weakened roots. Further clinical and long-term studies are required to confirm these findings.