Related Experiment Video
Updated: Dec 7, 2025
07:04
Confocal Time Lapse Imaging as an Efficient Method for the Cytocompatibility Evaluation of Dental Composites
Published on: November 9, 2014
13.9K
Effect of light-curing distance and curing time on composite microflexural strength.
Afnan O Al-Zain1, Jeffrey A Platt2
1Operative and Esthetic Dentistry Division, Restorative Dentistry Department, Faculty of Dentistry, King Abdulaziz University.
Dental Materials Journal
|October 1, 2020
Summary
Curing distance significantly impacts nano-hybrid composite flexural strength. Manufacturer-recommended curing time (MCT) or consistent radiant exposure (CRE) protocols showed varying results depending on the light-curing unit (LCU) and distance.
Area of Science:
- Dental Materials Science
- Polymer Chemistry
- Biomaterials Engineering
Background:
- Light-curing units (LCUs) are crucial for dental composite polymerization.
- Optimizing curing protocols, including distance and energy, is essential for material performance.
- Variations in LCU technology and curing parameters can affect composite properties.
Purpose of the Study:
- To investigate the effect of curing distance on the micro-flexural strength (µ-FS) of a nano-hybrid composite.
- To compare the µ-FS of composites cured using manufacturer-recommended curing time (MCT) versus consistent radiant exposure (CRE).
- To evaluate the influence of different LCUs (QTH, SLED, MLED) on µ-FS at varying curing distances.
Main Methods:
- Nano-hybrid composite beams were fabricated and cured using MCT or CRE protocols.
- Three LCUs (QTH, SLED, MLED) were employed at curing distances of 0, 2, and 8 mm.
- Bottom irradiance and CRE were measured, and µ-FS was determined via mechanical testing.
- Statistical analysis included two-way ANOVA and Tukey's multiple comparison tests.
Main Results:
- Mean bottom irradiance ranged from 25.4-99.7 mW/cm², and CRE ranged from 0.31-1.11 J/cm².
- µ-FS values ranged from 422.1-516.6 MPa (MCT) and 440.4-490.4 MPa (CRE).
- Significant decreases in µ-FS were observed with CRE at 2 mm (QTH) and with MCT at 2 and 8 mm (SLED).
Conclusions:
- Curing protocol, including distance and energy delivery, significantly influences the µ-FS of nano-hybrid composites.
- The choice of LCU and adherence to optimal curing parameters are critical for achieving desired material properties.
- Further research is needed to establish standardized, distance-independent curing protocols for various dental composites.
Related Concept Videos
01:20Strength of Cement
356
Strength tests for cement are not performed directly on neat cement paste due to difficulty in obtaining consistent, reliable specimens. Instead, cement is typically tested in the form of cement-sand mortar.
For compressive strength tests, ASTM C 109-05 standards prescribe a cement-sand mix ratio of 1:2.75 and a water/cement ratio of 0.485 for making 2-inch cubes. These cubes are mixed, cast, and cured in saturated lime water at 23°C until testing. Flexural strength testing, outlined in...
For compressive strength tests, ASTM C 109-05 standards prescribe a cement-sand mix ratio of 1:2.75 and a water/cement ratio of 0.485 for making 2-inch cubes. These cubes are mixed, cast, and cured in saturated lime water at 23°C until testing. Flexural strength testing, outlined in...
356
01:25Accelerated Curing of Concrete
349
Accelerating concrete curing is achieved by applying heat and additional moisture. This process accelerates the hydration of the cement, resulting in an earlier strength gain in the concrete. Steam curing is a method wherein the concrete products are either transported through a chamber on a conveyor belt or encased in plastic, allowing steam at atmospheric pressure to circulate freely around them. This process begins with a phase of moist curing that typically lasts between 3 to 5 hours, after...
349
01:20Curing of Concrete
264
The hydration of cement takes place within the water-filled capillary pores. However, environmental elements can disrupt this process by evaporating water from the concrete surfaces. Sealed concrete with a water-cement ratio below 0.5 experiences self-desiccation, leading to water loss. The water loss in concrete is mitigated by curing. This technique involves keeping the concrete saturated to maintain the necessary temperature and moisture conditions, to optimally fill the spaces in the cement...
264
01:20Microcracking in Concrete
322
Microcracking in concrete refers to the tiny cracks that can form within the material even before any external load is applied. These microcracks typically occur at the interface between the coarse aggregate and the hydrated cement paste, often as a result of differential volume changes prompted by variations in stress-strain behavior, as well as thermal and moisture movement. Initially, these microcracks remain stable and do not grow substantially until the concrete is stressed to about 30...
322
01:14Testing Water Quality
280
When the quality of water for concrete preparation is uncertain, its impact on the setting time of cement and compressive strength of mortar is assessed by comparison with de-ionized or distilled water benchmarks. American Society for Testing and Materials (ASTM) C1602 requires the setting times to be within 90 minutes of the control, British Standard (BS) 3146:1980 allows a 30-minute variance in the initial setting, while British Standards European Norm (BS EN) 1008 specifies initial setting...
280
01:30Relation Between Tensile Strength and Compressive Strength of Concrete
517
Concrete is a fundamental building material, and understanding its strengths is crucial for construction projects. The relationship between its tensile and compressive strengths is intricate, showing that while these strengths are related, they do not increase at the same rate. Tensile strength's growth is slower and is affected by various factors such as the methods used for testing, the size and shape of the specimen, the texture of the aggregate used, and the moisture content of the...
517