Can having a filling lead to a cracked tooth?

Not uncommon. A tooth restored with amalgam filling does not reinforce your teeth and it is common to see cracks and ultimately fractures of your teeth caused by the way the tooth is wedged with a metal filling between its cusp tips. Like any other filling, amalgam should be replaced with crown when cracks exist.
Many causes. Any time a tooth is stressed, either externally from biting pressures, bruxism, or a traumatic blow; or from internal stresses such as a cavity, a dental filling that expands and contracts differently from natural tooth structure, or an endodontically treated tooth with loss of vitality, it is more prone to tooth fracture. The larger the filling, the weaker the tooth, the greater the risk.
Depends. Fillings usually last a long time. Silver fillings are more likely to crack teeth acting as a wedge and also expanding and contracting at a different rate than the tooth when exposed to hot (coffee) or cold (ice). While not filling teeth is not an option, teeth with fillings are weaker than natural teeth.

Related Questions

Will a cracked tooth filling upset your stomach?

Unlikely. Depending on how deep the crack goes, you may need a replacement filling, you may need a crown, you may need a root canal and crown, or you may need to have the tooth taken out. Even a very deep crack is unlikely to cause an upset stomach although any infection associated with the cracked tooth may cause other problems. Best to see your dentist.
No. Bacteria can enter and cause more decay and lead to an abscess. See your dentist or you may lose your tooth.
Not likely, but. Is a possibility. The bacteria from an infected gums travels through the blood stream to other areas/organs of the body can cause bacteremia (bacteria in the blood) can also make you generally ill. With a good oral hygiene, brushing, flossing and professional cleaning this will never happen.

My #14 had a r/c 7 years ago. It's now very painful and I believe infected. Cracked tooth or maybe cracked filling??? Is an endodontist my best c

Yes. Definitely, an endodontist. Your regular dentist may be able to tell if the tooth is too far gone and has to be extracted.
See an Endodontist. The key is to have an Endodontist with the diagnostic skills to be able to do a proper diagnosis of your problem. An endodontist is a dentist who has completed a 2 or 3 year specialty program about root canals.
Tooth#14. If a tooth that had a root canal becomes painful, it usually means that the infection has returned, or never healed completely. It's also possible that the tooth is fractured, especially if did not have a crown placed after the root canal treatment. If the tooth is reinfected, the root canal will need to be redone. See your dentist for an accurate diagnosis.
Could be either. It could also be sinusitis. Please have a dentist evaluate the tooth. If the root canal needs retreatment or an apicoectomy, an endodontist is your best choice.

I'm 8weeks pregnant and had a silver filling placed while pregnant has had cracked tooth n needed it will my unborn baby be ok I have read it harmful?

No correlation. Your unborn will not be affected by that silver filling or any other silver fillings you might have. Amalgams have been placed for over 150 years on millions and millions of teeth, and countless millions have been born during that time period. You would think if they were dangerous there would be a detectable pattern. Forget what you've read. Others may disagree, but fact is fact.
You are ok! The amount of mercury in an amalgam "silver" filling is negligible. Treating your tooth problem properly allows you to continue through your pregnancy without that tooth being at risk for further problems, decay, and infection which are more detrimental to the health of your baby than getting a filling. Although I would prefer to place composite fillings free of metal, your baby should be fine.
Baby & U will be OK. As I have stated repeatedly on Health Tap, while mercury is part of silver fillings, decades of dental and medical scientific research have proven beyond a doubt that silver mercury fillings are safe. So don't and your unborn baby are totally safe.