Objectives. Light curing is crucial when applying composite resin restorations. Complete polymerization of the resin depends on delivering adequate light energy to it. Dental clinicians may be unaware of the importance of proper light-curing techniques. This study aimed at evaluating and comparing the level of knowledge of general practitioners (GPs) and specialists (SPs) regarding light-curing units. Materials and Methods. An electronic survey was conducted online among GPs and SPs of various specialties, working in the governmental sector in Riyadh, Saudi Arabia. Collected data were analyzed for statistical significance. Results. 310 dentists were included in the study. Nearly half of the GPs (45.9%) and more than half of SPs (56.8%) use light-emitting diode (LED) type light-curing units (LCUs). 36.9% of GPs and 29.6% of SPs were unsure about the type of LCUs they use in their dental clinics. 10.8% of GPs and 8.5% of SPs knew the proper term of the power output of LCU. 52.2% of the GPs and 55.7% of SPs were wrong about advancements in technology of LED LCUs. Regarding the use of radiometer, 48.2% of SPs and 35.1% of GPs had responded wrongly, and 37.7% of SPs and 52.3% of GPs were not familiar with the device, showing a statistical significance . There was no statistical significance observed in the responses pertaining to their years of experience, expected for two questions. Conclusion. Both GPs and SPs displayed inadequate knowledge regarding the use of LCUs. Further educational programs are recommended to spread awareness about the handling of LCUs among dental clinicians.

To evaluate the effect of light curing unit (LCU) types and distance from light curing unit tip on the translucency parameters (TP) of bulk fill composite materials. Two bulk-fill resin composites and one nanohybrid composite were used in this study. The specimens were divided into groups based on the type of curing unit used, and further subdivided based on the distance of the curing source to the surface of the resin composite. Translucency was evaluated at 4 mm thickness (for the bulk-fill) and 2 mm thickness (for nanohybrid) after curing using two different light curing units at zero, 2 mm, and 4 mm distance. The results were analyzed using two-way ANOVA at the significance level of a p-value of < 0.05. Among all the tested materials, Filtek Bulk Fill Posterior RBC showed the highest TP at 0 mm distance when cured with Blue phase G2 LED LCU and it was the least affected by the differences in distances. However, Filtek Z350 nanohybrid composite had no significant differences between the three distances when cured with Blue phase G2 LCU. Translucency values among the studied bulk-fill materials are affected by material composition, curing units and the distance of the tip of the light source to the restoration surface.

This review summarizes current knowledge on both the most used photoinitiator system in dental resin (camphorquinone) and the alternative photoinitiator systems employed in dentistry. The review focuses on polymerization mechanisms, in vitro evaluation techniques, and factors that influence the degree of conversion and hardness of dental resin-based materials. A comprehensive electronic literature search was performed using PubMed, Google Scholar, and Elsevier databases, covering publications from 1984 to 2025. More than 30 articles were selected based on their relevance to the scope of this review. Light-activated dental resin-based composites (RBCs) represent the most widely used restorative materials in clinical practice. However, effective polymerization of each photoinitiator system depends on the use of a compatible light-curing unit with an appropriate emission spectrum. Changes in the photoinitiator system can markedly affect the biomechanical properties of dental resins, including degree of conversion, hardness, and biocompatibility. This review provides a comparative analysis of RBCs formulated with different photoinitiators, such as camphorquinone, benzophenone, 1-phenyl-1,2-propanedione, trimethylbenzoyl-diphenylphosphine oxide, and benzoyl peroxide. The main objective of this article was to highlight alternative photoinitiators capable of overcoming the color drawbacks of camphorquinone, particularly yellow discoloration, while maintaining comparable mechanical performance. Although current evidence suggests that no alternative photoinitiator fully matches the effectiveness of camphorquinone, certain systems—such as benzoyl germanium derivatives and novel acylphosphine oxide photoinitiators used in combination with camphorquinone—appear promising for enhancing esthetic properties and increasing the degree of conversion of dental RBCs.

Adequate polymerization is essential for the mechanical performance and longevity of resin-based composites; however, recently introduced chemical cure, bulk-fill composites remain underexplored. This in vitro study compared the degree of conversion (DC) of a chemical cure bulk-fill composite (Stela, SDI) with those of a nano-hybrid light-cured composite (Filtek™ Z250, 3M). Sixty standardized disc-shaped specimens (5 mm × 2 mm; n = 30 per material) were prepared according to the manufacturer’s instructions. We measured DC using Fourier-transform infrared spectroscopy (FTIR) immediately after polymerization and at 5, 10, 20 min, and 24 h. Both materials showed a progressive increase in DC over time. However, the light-cured composite consistently achieved higher conversion values, reaching 62.39 ± 4.23% after 24 h compared with 47.58 ± 3.04% for the chemical cure composite (p < 0.001). These findings indicate that DC alone should not be considered predictors of composite performance.

Adequate polymerization is essential for the mechanical performance and longevity of resin-based composites; however, recently introduced chemically cured bulk-fill composites remains insufficiently investigated. This in vitro study compared the degree of conversion (DC) and surface microhardness (SMH) of a chemically cured bulk-fill composite (Stela, SDI) with those of a nano-hybrid light-cured composite (Filtek™ Z250, 3M). Sixty standardized disc shaped specimens (5 mm x 2 mm; n= 30 per material) were prepared according to the manufacturers instructions. The DC was measured using Fourier-transform infrared spectroscopy (FTIR) immediately after polymerization and after 5, 10, 20 minutes and 24 h. SMH was evaluated using Vickers microhardness tester before and after artificial aging by thermocycling (5,000 cycles). The light-cured composite exhibited significantly greater SMH then the chemical cured composite (95.01 ± 0.59 HV vs. 51.21 ± 0.50 HV, p < 0.001). Both materials demonstrated progressive increase in DC over time. However, the light-cured consistently achieved higher conversion values, reaching 62.39 ± 4.23% after 24 h compared with 47.58 ± 3.04% for the chemically cured composite (p < 0.001). These findings indicate that the DC and SMH alone should not be considered a predictor of composite performance.