How does a 9mm advancement affect my facial harmony? (Photo)

You have a very recessive chin based on the lateral ceph. I would recommend an advancement genioplasty of 9-1- mm. That is the extent of advancement that can be safely performed while maintaining bone contact. It does not appear that you will need a bone graft and the vertical height looks within the normal range.

You can adjust your chin with a genioplasty or a chin implant. Both can be done to provide more balance to the face.

It’s not unusual to have providers have slightly different opinions. This is often the case when there may be different approaches to treating the problem or when things are not straightforward. In complex situation it is more likely to have opinions vary from different providers.
Providers may have different opinions because of different personal experiences, differences in what they’ve learned during their training or differences in skill and experience
During each consultation, asked each provider to open up your portfolio and show you their entire collection of before and after pictures of previous patients who had similar facial characteristics to your own. An experienced surgeon should have no difficulty showing you the before and after pictures of at least 50 previous patients. A highly experienced surgeon should have hundreds or even thousands of before and after pictures to choose from.
This procedure can be done by both the plastic surgeons and oral surgeons. From my experience, it seems like oral surgeons typically have slightly more experience doing a sliding genioplasty while plastic surgeons sometimes prefer using implants. This is not any type of absolute statement and both backgrounds contribute greatly to this type of work.
Consider having consultations with doctors from both backgrounds.
Best,
Mats Hagstrom, MD