Greater Magic Fang

This spell functions like magic fang, except that the enhancement bonus on attack and damage rolls is +1 per four caster levels (maximum +5). This bonus does not allow a natural weapon or unarmed strike to bypass damage reduction aside from magic.

Alternatively, you may imbue all of the creature's natural weapons with a +1 enhancement bonus (regardless of your caster level).

Greater magic fang can be made permanent with a permanency spell.