I’ve heard that one shouldn’t use the same brand of toothpaste for an extended period of time as it may not destroy all kinds of bacteria in the mouth. Is this true?

All toothpastes basically contain the same ingredients. It is just a marketing ploy that some toothpastes contain special ingredients that can solve all your dental problems. You need not change your toothpaste unless you are using a whitening toothpaste, as prolonged use of this can damage your teeth. If you’ve been using a medicated toothpaste for a long time, it would be good to consult a dentist to treat the underlying cause rather than continuing using these toothpastes, as this would only control the symptom but not cure the problem. Remember that it’s not the toothpaste that is most important – it’s your brushing style that’s critical to maintaining good oral hygiene. Use only a pea-sized amount of toothpaste and brush your teeth at least twice a day.

I had a root canal treated tooth but my dentist says it has got re-infected. How is that possible?

The reasons are multiple: Firstly and most commonly – missed nerve tissue. Sometimes the nerve and dead tissue was not completely or thoroughly removed. It could be because the canals were not instrumented and filed down wide enough or long enough, or the solvent liquids haven’t been left in long enough. If canals are not prepared to an adequate size, the disinfectant solutions cannot reach all the areas of the nerve tissue and bacteria can live n in these areas and slowly reinfect. Sometimes an entire canal is missed because it did not get spotted during the initial checkup. Remember that the opening of the nerve canals can be as thin as 50 microns. It happens a lot less now because of better lighting, the use of magnification and microscopes and 3D CBCT scanning. Second, cement or filling breakdown. All cements have a life. Over a period, they breakdown and dissolve and can allow a passage for bacteria to re-enter the root canal system and cause a re-infection. Third, separated or broken instruments in the canal. Unfortunately, this happens in the best hands also occasionally. The newer generation of files which are used to clean the canals are a lot more flexible than the older generation but are also more prone to breakage. Not every broken file will cause a problem though. Frequently they can be bypassed or removed, and all is good. But occasionally both these options won’t work and a tooth might need to be removed as a last resort.