Learn Turkish: Yorgun değilsin, masaj yaptırmana gerek yok. - You are not tired, you don't need to get a massage.

To say 'you don't need to do an action' with gerek yok, Turkish uses a specific structure: the verbal noun -ma or -me, plus a possessive suffix, plus the dative suffix -a or -e. Here, we have yaptır (have done) + -ma (action of) + -n (your) + -a (to). It translates literally as 'there is no need to your getting a massage.'

Why use the causative form yaptırmana instead of just yapmana?

If you used yapmana, it would mean 'you don't need to give a massage' (you being the person doing the massaging). Adding the causative suffix -tır changes the verb to mean 'having it done' by someone else, which is how you say you are receiving a massage in Turkish.

Is the n in yaptırmana a buffer letter connecting the vowels?

No, it is the second-person singular possessive suffix showing who is doing the action. It stands for senin (your). The breakdown is yaptırma (the act of getting it done) + -n (your) + -a (dative case). If it were 'I don't need to', it would be yaptırmama (my getting it done).

Could I just say masaj yaptırmak gerek yok using the full dictionary form of the verb?