Once gingivitis progresses into periodontitis, it becomes irreversible destructive periodontal disease. Typically, they are plague/calculus induced.

It can be divided into the following categories
- Mild Periodontitis
- Moderate Periodontitis
- Severe Periodontitis
They are classified according to the pocket depth and bone loss around teeth.
In mild and moderate periodontitis, you may be benefitted from scaling and root planning are also known as deep cleaning. Once a plague buildup is left in the mouth for some time it becomes a solid structure called calculus. Both plagues and calculus buildup are a collection of bacteria causing inflammation in the gum tissue. You may be able to take plague off by brushing but once it becomes calculus buildup it would be almost impossible for you to get them off thus you would need professional dental cleaning.
Mild and moderate periodontitis are classified according to how much bone loss you have around teeth. With deep cleaning, it may be possible to avoid further progression. Remember, the bone losses are “irreversible”, meaning even with the deep cleaning procedure, you will not recover the bone loss. The whole point of doing the deep cleaning is to prevent it from getting worse. However, at this stage, it would have a relatively good prognosis after the procedure.
However, in severe periodontal case, you would already have mobility and too much bone loss and it would be possible that even after the deep cleaning it would not get any better. You may need extra advanced procedures from Periodontist such as bone graft and connective tissue graft to maintain your teeth.
Basic cleaning Vs. Deep cleaning?
Deep cleaning involves getting anesthesia. The difference between deep cleaning and basic scaling would be the location of where in the mouth that is being cleaned. Generally speaking, scaling (basic cleaning) involves cleaning only above the gum line. However, in you have calculus buildup below the gum tissue, you would need to get anesthesia for your dentist to clean below the gum line. This is why sometimes you feel like you don’t have much plaque buildup but your dentist recommends a deep cleaning. It is the amount of calculus buildup but most importantly the location of calculus buildup that determines whether you would need a deep cleaning or not. Sometimes, patients ask to get a deep cleaning although only basic cleaning would be sufficient. It would be wrong to perform a deep cleaning if you just need a basic cleaning. It can do more damage to your gum tissue by getting the deep cleaning. Therefore, the proper type of cleaning is needed and will be recommended by your dentist.
You can read the article about cleaning:
[https://www.midentalclinic.com/dental-cleaning-why-do-i-need-to-get-a-regular-cleaning/]
You can read the article about Gingivitis:
[https://www.midentalclinic.com/what-is-gingivitis/]
References:
https://www.mouthhealthy.org/en/az-topics/g/gum-disease
https://www.cdc.gov/oralhealth/periodontal_disease/index.htm
https://www.perio.org/newsroom/periodontal-disease-fact-sheet
https://en.wikipedia.org/wiki/Periodontal_disease