What is the primary function of a saliva ejector during coronal polishing?

The primary function of a saliva ejector during coronal polishing is to remove excess moisture and debris. This is crucial for maintaining a clear working area in the patient's mouth, allowing for better visibility and access to the teeth being polished. By removing saliva, water, and particles that may accumulate during the procedure, the saliva ejector helps ensure that the coronal polishing can be performed effectively without interruption. This function is vital for achieving optimal results while also making the patient more comfortable during the process. In contrast, the other options do not directly pertain to the essential role of a saliva ejector in this context.