To Rise Again at a Decent Hour by Joshua Ferris

There's nothing like a dental chair to remind a man that he's alone in the world . . .

Paul O'Rourke - dentist extraordinaire, reluctant New Yorker, avowed atheist, disaffected Red Sox fan, and a connoisseur of the afternoon mochaccino - is a man out of touch with modern life. While his dental practice occupies his days, his nights are filled with darker thoughts, as he alternately marvels at and rails against the optimism of the rest of humanity.

So it goes, until someone begins to impersonate Paul online. What began as an outrageous violation of privacy soon becomes something far more soul-frightening: the possibility that the virtual 'Paul' might be a better version of the man in the flesh . . .