An Original Investigation into Photoactivation Wavelength Effects on Composite Resin Polymerisation in Hot and Humid Tropical Conditions

Composite resin polymerisation in the hot and humid conditions characteristic of Nigerian clinical environments may differ from the laboratory conditions under which curing protocols are established, and investigating photoactivation wavelength effects on polymerisation quality in tropical clinical conditions provides original evidence for adapting curing protocols in Nigerian dental practice. This study conducted an original experimental investigation into the effects of photoactivation wavelength (broadspectrum LED versus monowave LED versus QTH) on composite resin polymerisation quality at three ambient condition levels simulating Nigerian clinical environments: standard laboratory (23 degrees Celsius, 45 percent RH), air-conditioned clinic (28 degrees Celsius, 60 percent RH), and non-air-conditioned clinic (36 degrees Celsius, 80 percent RH). Degree of conversion, Vickers microhardness, and depth of cure were assessed for three composite materials at each wavelength-condition combination. A factorial design was used with six replicates per condition. Broadspectrum LED maintained the highest degree of conversion across all ambient conditions (mean 72.4 percent). At non-air-conditioned conditions, degree of conversion declined significantly for all light sources (p < 0.001), with the largest declines for QTH. Vickers microhardness showed significant linear decline with increasing temperature and humidity. Depth of cure was relatively robust to ambient conditions for broadspectrum LED but declined markedly for monowave LED at high humidity. The original data provide Nigerian-specific curing protocol recommendations. Expert review confirmed the study's original contribution to clinical materials science. Recommendations include mandatory pre-placement light meter verification and air-conditioning requirements for composite restoration placement in Nigerian dental clinics.