Final answer:
The 5-year-old patient's upper central incisors have a deciduous crown that has fully formed but has yet to erupt through the gum line.
Step-by-step explanation:
Based on the information provided, the 5-year-old patient has yet to have their upper central incisors emerge, but the enamel on those teeth is already fully formed. This means that they have the crown already formed, but it has not erupted through the gum line yet. The crown of a tooth is the visible part above the gum line, covered by enamel, which is the hardest substance in the human body. In this case, the type of crown that has formed is the deciduous crown or baby crown.