minimally invasive dentistry... where do i draw the line?

when a patient comes in and asks me "how long" something will last, i usually give them ballpark averages from what i've heard and read (ie. fillings about 5-7 years, crown and bridge about 7-10 years, etc) but i always give them the caveat that no matter how well any work is done, all of the materials we work with have a limited life span and that things may eventually wind up being replaced or repaired. in fact, about 95% of what i do is replacing and/or repairing old and failing work. the fact is once you open up a tooth, you are officially married to it (so at this point i can safely say that i have about 1000 husbands!) and it becomes your responsibility. the mouth is a very harsh place, and even the tightest margins can leak, the strongest porcelains may fracture, the most disinfected canals become re-contaminated. but it never ceases to amaze me - how some of the most pristine, carefully executed work can fail, and yet some of the crap that passes for clincially acceptable by some standards has managed to last all these years. go figure.

take today, for example. about 2 months ago i did some restos on a guy, about college age. he had kissing cavities on #37 M and #36 D, just at the DEJ. could they have remineralized with some fluoride and floss? possibly, some may argue. but the guy's oral hygiene was absolutely abysmal and they looked quite broad inciso-gingivally on the radiographs, that something told me to go ahead and do them. i pulled out all the stops - rubber dam isolation (because yes, i do use them, especially when placing posterior resins), very conservative slot preparations, two step clearfil prime and bond system, beautiful margins, perfect occlusion, all good to go, right? nope, guy's been sensitive to biting ever since i touched the damned teeth so there was nothing left to do except remove the fillings today and place IRM. it broke my heart to remove all of my hard work, and it was so well-done (and i don't often pat myself on the back, either) but he was just not comfortable and when that happens, the treatment has failed. i worked on those teeth, they are now my babies. but what was i to do at that time? leave the asymptomatic caries there and allow them to potentially get worse? or "fix" the teeth but potentially cause him discomfort and/or inconvenience?

and then here's the real kicker - new patient walks in just a few hours later, HUGE amalgam overhang on #25 D, as if the dentist didn't even use a matrix band, and it has an associated localized perio defect. the tooth is completely asymptomatic, just "bleeds a little when i floss". not even noticed by the patient until i point it out. how the hell does this happen??? how does such negligence go undetected? and why is my hard work "cursed" with problems while this guy can get away with something like that? why, why, WHY???

it feels like no matter how hard one may try, dentistry is just not an exact science. i guess that's what can be so frustrating sometimes. you try to do good work , and in the end it just so happens that you can make seemingly okay situation worse. so when patients ask me to guarantee my work, i simply say, "the only tooth i can guarantee is the one a dentist has NOT worked on, so you better take care of the ones you got." and that is why i definitely espouse the philosphy of minimally invasive dentistry. my question is, though, when do you cross the line from a conservative approach to supervised neglect? how can you distinguish the two? what do you treat, and what can you leave alone? what is more harmful?

man, i wish i had an office job....