Impact of Secondhand Smoke on the Biomineralization of Dental Enamel in Rats

This study aims to investigate the qualitative and quantitative morphological changes in dental enamel resulting from SHS exposure during early childhood, utilizing an animal model. Wistar rat offspring were divided into a control group (n = 15) and an SHS exposure group (n = 19). The experimental group was subjected to cigarette smoke twice daily for 5 min, from postnatal day 2 to day 28. Throughout the experimental period, growth was monitored by measuring both weight and body length. Dental enamel was assessed through photographic analysis, micro-computed tomography (micro-CT), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and microhardness testing. Mandibles were processed, followed by hematoxylin and eosin staining. Data analysis was conducted using Student's t-tests (⍺= 5%). There was a significant reduction in weight gain in the SHS-exposed group compared to controls (p < 0.0001). Macroscopic examination revealed no structural differences in the incisors or molars of SHS-exposed offspring relative to controls. SEM analysis demonstrated increased spacing between superficial enamel prisms was noted in the SHS group. In terms of chemical composition, significant decreases in phosphorus content (p = 0.033) and increases in carbon content (p = 0.017) were detected in the molars of the SHS group, with no significant differences found in calcium, oxygen, or the calcium-to-phosphorus ratio. Micro-CT analysis showed no changes in enamel volume or microhardness, and no significant differences were detected in ameloblast morphology. In conclusion, while SHS exposure did not induce macrostructural changes in enamel, it was associated with reduced phosphorus levels, increased carbon levels, and greater spacing between superficial enamel prisms leading to a mild disturbance in dental mineralization.