BMC oral health · 2026
Fracture strength of conventional versus digital interim crowns after thermal cycling.
СтатьяСравнительное исследованиеНазвание и аннотация: Перевод в очереди
Обработка статьи · этапы, ошибки и управление
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История · было → стало
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Sarıkaya Işıl, Koç Tuğçe, Usta Kutlu İlknur
Аннотация
BACKGROUND: Provisional restorations are essential components of fixed prosthodontic treatment. This study compared the fracture strength and failure modes of provisional crowns fabricated using conventional direct, conventional indirect, CAD/CAM 3D printing, and CAD/CAM milling techniques after thermal aging.
METHODS: A total of 48 provisional crowns were fabricated across four groups (n = 12 per group): conventional direct technique using dual-cured composite resin (Tempsmart DC, GC Corporation, Tokyo, Japan), conventional indirect technique using autopolymerized PMMA (Temdent Classic, Schütz Dental GmbH, Rosbach, Germany), CAD/CAM 3D printing using light-cured resin (ResMach Interim, ResMach, Istanbul, Turkey), and CAD/CAM milling using pre-polymerized PMMA (Acryx, Akrodent, Istanbul, Turkey). All crowns were cemented onto standardized cobalt-chromium dies and subjected to 10,000 thermocycles alternating between 5 °C and 55 °C (30-second dwell time; 5-second transfer time). Fracture strength testing was performed using a universal testing machine at a crosshead speed of 1 mm/min until failure, with maximum loads recorded in Newtons. Fracture modes were classified using Burke's classification through visual and photographic analysis. Statistical analysis was performed using one-way ANOVA and Tamhane's T2 post-hoc test (p < 0.05).
RESULTS: The highest fracture strength was recorded in the Acryx group (1511.67 ± 140.73 N), significantly higher than all other groups (p < 0.001). The ResMach Interim group showed the lowest fracture strength (581.62 ± 51.86 N). Conventional groups (Tempsmart DC: 716.58 ± 104.81 N; Temdent Classic: 792.85 ± 83.70 N) had intermediate values. One-way ANOVA revealed a large effect of fabrication technique on fracture strength (η² = 0.857). Acryx exhibited predominantly Class II fractures (75.0%), while other groups showed Class I fractures (83.3-100%).
CONCLUSIONS: CAD/CAM-milled PMMA crowns demonstrated superior fracture resistance and more favorable ductile fracture patterns compared to conventional and 3D-printed crowns after thermal aging, suggesting these materials may be preferred for long-term provisional use in high-stress clinical scenarios such as posterior region applications.
METHODS: A total of 48 provisional crowns were fabricated across four groups (n = 12 per group): conventional direct technique using dual-cured composite resin (Tempsmart DC, GC Corporation, Tokyo, Japan), conventional indirect technique using autopolymerized PMMA (Temdent Classic, Schütz Dental GmbH, Rosbach, Germany), CAD/CAM 3D printing using light-cured resin (ResMach Interim, ResMach, Istanbul, Turkey), and CAD/CAM milling using pre-polymerized PMMA (Acryx, Akrodent, Istanbul, Turkey). All crowns were cemented onto standardized cobalt-chromium dies and subjected to 10,000 thermocycles alternating between 5 °C and 55 °C (30-second dwell time; 5-second transfer time). Fracture strength testing was performed using a universal testing machine at a crosshead speed of 1 mm/min until failure, with maximum loads recorded in Newtons. Fracture modes were classified using Burke's classification through visual and photographic analysis. Statistical analysis was performed using one-way ANOVA and Tamhane's T2 post-hoc test (p < 0.05).
RESULTS: The highest fracture strength was recorded in the Acryx group (1511.67 ± 140.73 N), significantly higher than all other groups (p < 0.001). The ResMach Interim group showed the lowest fracture strength (581.62 ± 51.86 N). Conventional groups (Tempsmart DC: 716.58 ± 104.81 N; Temdent Classic: 792.85 ± 83.70 N) had intermediate values. One-way ANOVA revealed a large effect of fabrication technique on fracture strength (η² = 0.857). Acryx exhibited predominantly Class II fractures (75.0%), while other groups showed Class I fractures (83.3-100%).
CONCLUSIONS: CAD/CAM-milled PMMA crowns demonstrated superior fracture resistance and more favorable ductile fracture patterns compared to conventional and 3D-printed crowns after thermal aging, suggesting these materials may be preferred for long-term provisional use in high-stress clinical scenarios such as posterior region applications.