- The primary drawback of using zinc phosphate cement in dental procedures is its pulpal irritation caused by its initially low pH.

- Zinc phosphate cement is widely used because of its good mechanical properties and excellent adhesive capabilities to tooth structures. However, during the initial setting phase, the cement exhibits a very acidic environment with a pH as low as 3.5. This low pH can irritate the dental pulp, especially if the dentin layer is thin or if the pulp is already compromised.
- This is an important consideration when placing zinc phosphate cement near the pulp; protective liners or bases are often applied to mitigate this effect.

The other options present common considerations but are less significant with zinc phosphate cement:
- High solubility (Option 1): Zinc phosphate cement has relatively low solubility compared to other cements, so early dissolution is not a primary issue.
- Insufficient mechanical strength (Option 3): It has reasonable compressive strength suitable for many dental applications, including some load-bearing restorations.
- Long setting time (Option 4): Zinc phosphate cement typically has a moderate setting time and does not substantially delay treatment.

In summary, the initial acidity and potential for pulpal irritation is the main limitation that clinicians must be aware of when using zinc phosphate cement.

Reference: Smith BJ, Powers JM. *Craig's Restorative Dental Materials*, 13th Edition, Chapter 6 - Dental Cements, Page 120-122.