Hello, It is advisable to go to your dentiat and let yr tooth be examined... A radiographic interepretion will be definately useful and defintely aid in diagnosis..

Consult a dentist for proper diagnosis.

Hi Pain will not happen even in the chronic stage of cavity or in the initial stage too.... You need to go for clinical and radiological examination of your teeth to check for the extension of the cavity If it is in initial stage and does not involve nerve layer then normal filling is enough to save your teeth If nerve layer is involved by caries then you need to go for Root canal treatment... No local anesthesia is not needed for teeth cementation

Dental x-ray is required to know that

It depends on how deep the cavity is n how much natural tooth structure is remaining. If the cavity is in enamel and dentin then composite filling should be done and not cement. If cavity is very close to pulp or touching the pulp or there is infection at root apex, RCT & crown is recommended. If more than 55% tooth is decayed, it's difficult to save n retain such tooth. Decision can be taken only on an x-ray.

Any tooth  cavity big or small, painful or painless has it's own bad effects.