In vitro study reveals material-dependent effects of margin design on fracture load in deciduous molar crowns, indicating preparation selection affects repairability.
Key Points
Evaluate the effects of restorative material type and margin preparation design on the fracture load and failure behavior of CAD-CAM crowns for deciduous molars.
Tested three subtractive-manufacturing materials and two additive-manufacturing materials prepared with knife-edge, chamfer, or deep chamfer margins.
Bonded crowns to standardized deciduous molar abutments (n = 12 per group, total N = 180).
Measured fracture load under static loading, categorized fracture modes by repairability and abutment involvement, and examined crack propagation via scanning electron microscopy.
Significant differences emerged across materials and material–margin interactions (p < 0.05).
ESTELITE BLOCK II achieved the highest fracture load with knife-edge margins, while Detax peaked with deep chamfer margins; however, knife-edge designs for both materials caused non-repairable abutment fractures.
CERASMART PRIME demonstrated lower fracture loads but primarily repairable fractures, whereas additive-manufactured crowns exhibited interlayer delamination and radial cracking.