PLEASE READ THEORY BEFORE DOING ANYTHING
I do not expect that many people will try that, but if someone is so desperate better do not repeat stupid mistakes.
In my case that was just temporary fix for few weeks and i mostly use usual dentist service.
Not everybody can afford professional tooth repairs, and free goverment subsidized service is usually so bad that they do more damage than repair.
My father lost few good teeth because dentists considered them to much damaged to repair cheaply.
I had problems with my wisdom teeth so since there was nothing to loose I decided to repair them myself. It is just temporary repair, until I will find some dentist to extract them properly.
It appears to be not so impossible as you may expect. however wisdom teeth are very hard to reach and so work is complicated so quality is questionable.
There are 2 options for tooth repair, fillings or crowns, dentists especially cheap ones are in love with fillings. They don't last long and each repair does irreversible damage.
Crowns are best solution but somehow quite expensive even if there is no reason for them to be so.
Surprisingly, crowns are not so hard to make as you think, you can find instructions how to make vampire teeth for Halloween and without modifications these methods are usable for tooth repair too.
Only difference is that you need to glue them permanently.
Big filings are much harder to do for yourself. And also you risk to be unable to remove them in case of emergency.I would not recommend permanent DIY filings unless you have dental drill. It is best to avoid them because even professional doctors cant make them properly.
tiny filings are easy to do and are worth trying.
DISCLAIMER: this looks like medical procedure, but technically it is not since none of these instructions involve any work with living flesh(I only recommend very minor repairs). However it is possible to do some damage, and I am not responsible for that. especially if you try to repair heavy damage there is big chance that something will go wrong.
I am not a doctor and I will gladly accept suggestions or critic from any dentist.
Step 1: Materials and tools
If you intend to do permanent repairs, then you need good quality materials. (even then it is quite unlikely to have great success.)
Crowns can be made of fiberglass+epoxy or acrylic resin. almost all materials are ok, if you are satisfied with color and strength.
most or stuff can be obtained from medical supply shops
If you want to do filings you need something that cures fast, so epoxy is bad choice, or be prepared to walk with open mouth for 3 hours or find some fast epoxy.
Cheapest solution is acrylic resin.
For temporary filings you can use simple plaster, it is great while you are waiting for appointment of just currently do not have time to visit dentist.
To do job properly you need to prepare tooth surface somehow, cheap dremel is OK for that, but it is better to buy dental handpiece from ebay if you intent do do more repairs.
Simple sharp rod will do the cleaning job because decayed bone is very weak and easy to scrap.
But only diamond burs can defeat enamel without shaking your head too much.
Most vital tool in dental repair business is air blower, without it do not even try to do anything.
big fish tank compressor will work fine, refrigerator compressors may also be suitable but some oil filter may be necessary.
Blunted hypodermic needle will make fine nozzle.
Also you will need big syringe with blunt needle as water squirter to wash tooth surface.