Dear Anonymous, There is a middle ground when it comes to sensitivity from cold water to a tooth. If the only time the tooth hurts is when cold water or drinks are used and the pain goes immediately away, then the patient could be suffering from tooth wear or abrasion at the gumline. If the tooth pain stays with the patient for a length of time or is accompanied with pain while eating, then the chances of root canal are much greater. A checkup and tooth sensitivy testing could determine which of these scenarios seem most reasonable. If the pain is just tooth sensitivity to cold, therefore, you could get away with just a filling or desensitization treatment.
I hope this explaintion helps.