Effect of composite insertion technique on cuspal deflection using an in vitro simulation model.

Area of Science:

• Dental Materials Science
• Restorative Dentistry
• Biomaterials Engineering

Background:

• Composite resins are widely used in dental restorations.
• Insertion techniques can influence stress and strain within restorations.
• Cuspal deflection is a critical factor affecting restoration longevity and tooth integrity.

Purpose of the Study:

• To evaluate the impact of different composite resin insertion techniques on cuspal deflection.
• To compare the cuspal deflection of conventional composites with a novel low-shrinkage composite.
• To analyze the influence of preparation depth on cuspal deflection.

Main Methods:

• Simulation study using typodont artificial teeth with standardized MOD preparations.
• Comparison of four insertion techniques: bulk, horizontal increments, tangential increments, and modified tangential.
• Measurement of cuspal deflection using Linear Variable Differential Transformers.
• Evaluation of both conventional (Spectrum TPH) and low-shrinkage (Filtek LS) composites.

Main Results:

• Conventional composite insertion techniques resulted in significant cuspal deflection, ranging from 25.80 ± 4.98 μm to 55.62 ± 8.16 μm.
• Deeper preparations (6 mm) generally exhibited greater cuspal deflection than shallower ones (4 mm), except for bulk insertion.
• The low-shrinkage composite demonstrated markedly reduced cuspal flexure, measuring 11.14 ± 1.67 μm and 16.53 ± 2.79 μm for 4 mm and 6 mm depths, respectively.

Conclusions:

• All tested insertion techniques with conventional composites induce cuspal deformation.
• Preparation depth influences cuspal deflection, with deeper preparations showing more significant movement.
• Low-shrinkage composite materials significantly minimize cuspal movement, indicating potential for enhanced clinical performance.