Teething and fever....?

my youngest, now 17months, has always had a slight fever when cutting each and every tooth (14 teeth now)...more so, he always cuts his teeth in pairs or within days of each other which I think is related to the fever as his body is doing over time. However, these fevers have usually been slight, maybe 38 or so at most and not too long lasting, so at 40C for 24hours I would be thinking maybe it were a virus but the thing is we'll never know lol, but to me it seems a bit to coincidental to not be the teeth causing the temps all the time but whether this temp is from the teeth is hard to tell.