Dental surgeon dont give warranties on dental implants,because dental implants are medical devices like stent, prosthetic valves, cochlear implants etc for which any doctor never gives warranty and guaranty. Dental implants success depends upon a lot of factors like the level of oral hygiene by the patients, regular brushing, flossing, routine check up. An ethical dentist always stands behind their work,
If defects in the work or material comes to light they would probably fix it free of charge.
They are not under legal obligation to do so but they might do it anyway. Promotion like life time warranty ,10 yrs warranty all these false committments are unethical practice.
Even God has not given any warranty for his natural teeth. For me I always say that I will replace any failed implants that does not integrate or withstand the loading phase initially.