This is because tooth decay is so similar to sin decay. Little openings which grow worse when simple disciplines are overlooked. [Or, when we allow the wrong things to fill our mouths]. Sow an attitude and you reap a habit, a character, and then a life. The spiritual life goes better when we give attention to small details.
I was at the dentist yesterday. So I've been thinking a lot about sin in the last 24 hours. I won't bore you with my file of awful dentist experiences! But this time he looked into my hole-y mouth (I have a few gaps now) and gently chided me about how if I didn't wait so long to come in and I wouldn't have so many situations that are unsalvageable.
Now there is a word to get stuck in my gullet (just beyond my final tooth).
Maybe this is where tooth decay is so different from sin decay? Because there is no sin situation that is unsalvageable. There is no sin situation beyond the touch of God's restoring grace expressed to us in Christ's redeeming death.
I might stand at the sink and brush vigorously hoping that such brushing will salvage a bad situation. But it won't. It never will. But I can kneel at my chair and confess quietly knowing that such confession will salvage a bad situation. It will. It always will.