Masterclass

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Complete Reflection

Tapan Patel (TP):

This year more than any other, as I mentioned at the beginning and largely because there has been a product launch, I’ve done more chin work than ever before in my career. I’m thoroughly enjoying the results, and truly getting some very impactful results, but I’m aware that probably the gold standard for the chin is a genioplasty. Again, I’m not sure really what that involves but I wonder if you could just give me an overview of genioplasty.

John Blythe (JB):

Sure, so a genioplasty may be suitable for patients who have a deficient, asymmetric, or overprojected chin, on the background of a relatively normal dental bite or occlusion. We’re purely going to focus on the genioplasty and there won’t be any other mandibular surgery that is necessary. This, again, is carried out under general anaesthesia – the patient is nicely asleep and all the treatment is performed, certainly in my hands, intraorally so there is no external scar.

TP:

Sure.

JB:

An incision is made just behind the lip, approximately running from canine tooth to canine tooth, so a relatively small incision. The chin is exposed, paying meticulous attention to preserving the mentalis, and it is going to be an important aspect upon closing and preventing chin ptosis after the procedure, that we redrape the mentalis correctly. When we’ve exposed the chin, there are 2 main important structures that we must avoid.

Firstly we have the mental nerve, and from this model, you can see the mental foramen that sits just below the apices of the second and first premolars. This is where the mental nerve, which is a branch of the inferior alveolar nerve and V3 of the trigeminal nerve, exits. There are 3 branches; one to the gingiva, one to the chin, and one to the lips. This is an area that we must protect with as much care as possible. The second thing we have to be careful of is damaging the dental roots, so any chin osteotomy must obey certain rules. We aim for 5 mm below the apices of those roots otherwise there’s a risk of dental injury. If I can show you on the model, once the bone is exposed, you would very, very carefully mark out, either with a sterile marking pen or with a very fine bur, the midline. You need to make sure that you don’t introduce any rotations unless you’re meaning to, so you would place a very fine gauge sagittally, or vertically, at the symphysis of the bone. Then, you want to create a horizontal reference point, and this reference point should be 5 mm below the apices of the central incisors. Marking out, you also want to be 5mm below the mental foramen, gently coming out to the inferior border.

Once the structures have been identified and protected, potentially with an elevator, you carry out the outer cortical osteotomy first, and this can be with a long bur or with a piezoelectric saw.
There is an outer cortex and an inner cortex, and the inner cortex we have to take care of because the extrinsic tongue muscles and the anchorage points for the tongue will be positioned behind this area, including some significant vessels.

TP:

Understood.

JB:

So with great care, you are going through both the outer and then the inner cortex, and you may use osteotomes, or fine surgical chisels, to gently mobilise the chin point.

TP:

Okay. Once you’ve mobilised the chin point, then what are your options?

JB:

If this patient has a deficient chin only and we’re looking to slide the chin forward, we would then bring it forward from a predetermined distance, and we would have made those decisions following software planning prior to surgery. For patients who have asymmetries, we may need to do a subsequent osteotomy to remove a wafer amount of bone on one side so that we can balance it out.

TP:

In a previous video, you told me that the range of movement that you could get with the osteotomy, a mandibular osteotomy, was somewhere between 4 and 10 millimetres, what sort of advancement in the chin projection can you hope to get here – what’s the range?

JB:

I think this is a very good question Tapan. We need bone to be meeting bone, so if, for example, the thickness of the symphysis in this area is 10 mm, you’re not wanting to go beyond 10 mm. However, you need some boney overlap, so going 5/6/7 mm would be safe. Going beyond that, you may then have to think of a staircasing approach, where you have an intermediate fragment so that there is sufficient bone contact to allow boney union.

TP:

Perfect, are there any particular issues that the patient has to be aware of after surgery? What’s the recovery and how long does it take for them to resume normal activities?

JB:

I would recommend patients have 3 to 5 days downtime and probably a light social calendar for the following 10 days to 2 weeks. If you’re a sportsperson then having contact sports within the first 6 weeks may be risky. Those are my main concerns.

TP:

Perfect, thank you very much, John.