There are several causes for dental diseases but the main cause is improper brushing.
Apart from this, dental diseases could also run in the family. Improper brushing leads to:

a) Food retention in the grooves present over the surface of tooth resulting in dental decay.

b) Food retention between two adjacent teeth and between tooth and gums
resulting in gum infection

TNo matter what kind of brush or paste one uses, it is the correct technique of brushing that is more important. Our periodontists will guide you with the correct technique of brushing.

Ideally 3-5 minutes of gentle brushing using the correct technique is enough for good effective cleansing of teeth.

Unknowingly some people brush for prolonged periods and in an improper method
This has detrimental effects like

- Wearing away of teeth (Abrasion)
- Receding of gums (Recession)

Normally, the outermost layer cover of tooth is enamel. It is the hardest tissue in the human body and protects the deeper tissues of the tooth. If for any reason like routine mastication or excessive abnormal brushing or injury to the tooth, the enamel cover is worn away exposing dentin. The patient develops mild / severe pain on having hot/cold / sweet substances or when he sucks air. This is because the underlying dentin is irritated.

Initial tooth decay that is confined only to the enamel can definitely be filled. But deep dental decay progressed and involving the pulp (nerves) cannot be filled.

In case of deep dental involving pulp, two types of treatments can be suggested:

i) Root Canal Treatment, where not of much tooth structure is destroyed.

ii) Tooth extraction, when the tooth is very badly decayed.

Gone are the days when tooth extractions / dental procedures were painful. Today, due to advancements in the field of dentistry, the treatment procedures have become much easier and more comfortable to both the dentist and the patient. Depending upon the procedure an appropriate anesthetic injection is given to the patient which makes the procedure painless to the patient

When the dental decay has progressed to involve the pulp of the tooth, the infected pulp tissue is removed, thoroughly cleansed, made sterile and a biocompatible material is placed/filled into the root canals and pulp chamber, followed by a cap.

Yes, it is mandatory to place cap over the treated tooth because after RCT the tooth tends to become more brittle and may easily break away.

There is no relation between extraction of a tooth and the eyesight.
The different distinct nerves supply the eyes and teeth.

It appears to be very good. The basic problem here is not with the tooth. Due to poor maintenance, there is destruction of tooth supporting apparatus the gums and bone (the foundation). With minimal amount of destruction of bone, the tooth can be saved. But however good a tooth appears, if there is no adequate bone support, it cannot be saved.

Treatment of a mobile tooth depends on the severity of mobility.

In teeth where the mobility is mild it can be splinted together taking support of adjacent healthy teeth by using a wire and a tooth coloured material.

Extraction is the only option for teeth with severe mobility.

While there is no truth in the statement that teeth become loose after cleaning with minimal deposits over the teeth, one may see some mobility in teeth where there are plenty of deposits. In such cases there is bone loss, and the space that was earlier occupied by bone, is now occupied by deposits and so the teeth appear to be firm. But after cleaning due to removal these harmful deposits the support is lost and the teeth appear to have become loose.

After cleaning the teeth may show a slight degree of sensitivity on intake of cold and sweet foods but this will gradually decrease over a period of 2 ± 4 weeks.

It is often advisable to see your dentist atleast once in a year, if not in 6 months and seek opinion about your oral health status.