Clinical oral investigations · 2026
Effect of tooth preparation design on fracture load and fracture behavior of deciduous crowns fabricated by subtractive and additive manufacturing.
СтатьяНазвание и аннотация: Перевод в очереди
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Hamashima Misaki, Wada Kanae, Oishi Shinya, Takahashi Hidekazu, Kohi Kaori, Kondo Daiki, Shin Yujeong, Yamanaka Yuika, Oishi Atsushi, Sugimoto Asuna, Kishima Kanako, Nakashima Yumiko, Kurogoshi Rika, Iwamoto Tsutomu
Аннотация
OBJECTIVES: This study evaluated the effects of crown material and margin design on fracture load and behavior of computer-aided design/computer-aided manufacturing (CAD-CAM) crowns for deciduous molars.
METHODS: Three subtractive-manufacturing (SM) materials and two additive-manufacturing (AM) materials were evaluated. Crowns with knife-edge, chamfer, and deep chamfer margins were fabricated and bonded to standardized deciduous molar abutments (n = 12/group; total = 180). Fracture load was measured under static loading, and fracture modes were classified by repairability and abutment involvement. Fracture surfaces and crack propagation were examined by scanning electron microscopy.
RESULTS: Significant effects of material and material-margin interactions were observed (p < 0.05). ESTELITE BLOCK II exhibited the highest fracture load with knife-edge margins, whereas Detax showed the highest values with deep chamfer margins. However, non-repairable abutment-involving fractures occurred in both materials with knife-edge margins. CERASMART PRIME showed lower fracture load but mainly repairable fractures. SHOFU BLOCK HC and CERASMART PRIME, unified crown-abutment fracture in ESTELITE BLOCK II, interlayer delamination in Detax, and superficial radial cracking in NextDent.
CONCLUSIONS: The effects of margin design on fracture load and fracture behavior were material-dependent. Among subtractive-manufacturing materials, fracture load was generally consistent with reported mechanical properties, whereas fracture behavior in additive-manufacturing materials may have been influenced by internal structure and build orientation. Material selection should consider fracture load, fracture severity, and abutment involvement.
CLINICAL RELEVANCE: Material and margin selection influence fracture resistance and failure patterns. Fracture severity and abutment involvement should be considered in addition to fracture load.
METHODS: Three subtractive-manufacturing (SM) materials and two additive-manufacturing (AM) materials were evaluated. Crowns with knife-edge, chamfer, and deep chamfer margins were fabricated and bonded to standardized deciduous molar abutments (n = 12/group; total = 180). Fracture load was measured under static loading, and fracture modes were classified by repairability and abutment involvement. Fracture surfaces and crack propagation were examined by scanning electron microscopy.
RESULTS: Significant effects of material and material-margin interactions were observed (p < 0.05). ESTELITE BLOCK II exhibited the highest fracture load with knife-edge margins, whereas Detax showed the highest values with deep chamfer margins. However, non-repairable abutment-involving fractures occurred in both materials with knife-edge margins. CERASMART PRIME showed lower fracture load but mainly repairable fractures. SHOFU BLOCK HC and CERASMART PRIME, unified crown-abutment fracture in ESTELITE BLOCK II, interlayer delamination in Detax, and superficial radial cracking in NextDent.
CONCLUSIONS: The effects of margin design on fracture load and fracture behavior were material-dependent. Among subtractive-manufacturing materials, fracture load was generally consistent with reported mechanical properties, whereas fracture behavior in additive-manufacturing materials may have been influenced by internal structure and build orientation. Material selection should consider fracture load, fracture severity, and abutment involvement.
CLINICAL RELEVANCE: Material and margin selection influence fracture resistance and failure patterns. Fracture severity and abutment involvement should be considered in addition to fracture load.