As a dentist we hear this so many times patients saying " I did not see a dentist all these years as I never had a problem or nothing was hurting so far"!! It's so fairly common that I repeat the words as my patients say it!  

Patients need to be educated that pain is a later symptom that arises after an existing  problem has been there for quite some time. If there is a cavity in a tooth which has probably slowly worsened over months and maybe years before it started hurting! When the cavity is in the enamel does not hurt, when it reaches the dentin it may get sensitive in which case seen by a dentist can get a filling (restoration) done and prevent the cavity from growing big and reaching the nerve (pulp) if ignored can decay and can reach the nerve and will need a RCT (root canal treatment).

 Another very common problem is gum problems ( bleeding gums, bad breath) which in the initial stages does not have any symptoms mild if at all any, over a period of time has built in and causing supporting bone and tissues of the teeth get affected leading g to early loss of teeth, sometimes in the early stages of gum issues (periodontal ) just a regular dental cleaning ( scaling ) can prevent bone loss and preserve teeth longer!

Several other dental problems like wear in the teeth,cracked teeth in adults, early teeth troubles in children which lead to bad bite and affect permanent dentition can be prevented  by visiting a dentist routinely even when teeth are not hurting!!