I trust my dentist to do an implant but i hope he does not cut into my mandibular nerve. do i ask if the positioning of this nerve can be a problem?

Don't hope: Have faith. Ask if you would like, but since you already trust your dentist, what do you expect as an answer?

Always ask.: You should always ask ANY question that you think is important. In this case, the dentist should be able to show you radiographic evidence to support the answer- possibly 3D data. However, implants are very common and not as scary as the internet might make you believe.

Prevention is key: Nerve injury during implant placement is a preventable by using CBCT-based surgical stent or other navigation system.

CT scan: If you feel more comfortable, have an an oral surgeon or periodontist place the implant and have your general dentist restore. There is always an inherent risk in every procedure, but with a CT scan and radiographs, you should be fine.