Which of the following is also implicated in enamel hypoplasia or dysplasia?

Nutritional deficiency is indeed a significant factor implicated in enamel hypoplasia or dysplasia. During the critical periods of enamel formation, inadequate intake of essential nutrients—specifically vitamins and minerals—can lead to improper development of the enamel layer, resulting in thinner or defective enamel. This issue can manifest as pits, grooves, or overall insufficient enamel covering on the teeth.

Physical trauma typically affects the teeth post-eruption, causing enamel damage rather than dysplasia at the developmental stage. Congenital defects may involve other dental anomalies, but they are distinct from the direct impact of nutrition on enamel formation. Environmental toxins, while they can influence various developmental issues, also don't specifically relate to enamel hypoplasia as directly as nutritional deficiencies do. Thus, nutritional deficiency stands out as a direct cause of enamel development issues.