Search

What’s in a gummy smile?
How can I treat it | Part 2

This blog (part 2) will explore the treatments available for managing Gummy Smiles, and follows on from part 1, where we discussed the assessment and diagnosis of the presentation. The process of assessment was described through the excellent seven steps of the Gummy Smile Assessment Tool by Dalya El-Bokle 2022. There are three categories of treatment, one of which is orthodontic and two are surgical options, each relating to the diagnosis detailed in part 1. The key difference with the orthodontic option is the effects are indirect, through the movement of the dentition, the gingiva repositions, by virtue of the relationship of the dentition to the periodontal ligaments.

 

Orthodontic anterior intrusion

 

Indication: Over-eruption of the dentition
Secondary indication: camouflage for vertical maxillary excess

Intrusion of the anterior dentition has a remodelling effect on the surrounding tissues, including the superior repositioning of the gingiva. The quantity of change possible from dental intrusion is between 2.6-2.9mm El- Namrawy 2019. Therefore, the changes possible are moderate, resolving a mild Gummy Smile (2-4mm) and reducing a moderate Gummy Smile (4-8mm). However, a severe Gummy Smile (8mm+) is unlikely to receive significant aesthetic benefit from the orthodontic intrusion alone.

Intrusion of the upper arch can be delivered through conventional intrusion arch mechanics, as well as miniscrew intrusion mechanics. There are three main challenges with intrusion mechanics;

  1. Extrusion of posterior teeth: Extrusion of posterior teeth occurs as a reciprocal moment from the anterior intrusion moment.
  2. Proclination of the anterior teeth: If the intrusive force is applied on the central incisors, there is a counter clockwise or proclining moment produced, which can be unfavourable.
  3. Buccal–palatal molar inclination: Reciprocal effects from anterior intrusion also create a buccal or palatal force of the posterior teeth, creating either excessive buccal flaring or lingual tipping.

Intrusion arch and miniscrew intrusion arch

Long-established is the use of intrusion arches, to reliably enable upper anterior intrusion. However, for one-piece intrusion arches, there is a likelihood of proclination of the anterior teeth. The inclusion of a transpalatal arch and tip-back bends can help to counter some of the undesirable moments, however, there remains a risk of the occurrence.

A solution to the above is the incorporation of 2 miniscrews in the molar region, enabling an intrusive force to the incisors, without the reciprocal extrusion of the posterior teeth. The addition of retraction forces through elastomeric chain manages the proclination of the anterior teeth, achieving more intrusion than proclination.

Full arch intrusion

Full arch intrusion becomes a possibility with the use of miniscrews. To achieve full arch intrusion, the resultant force is required to act through the centre of resistance of the maxilla, near the middle of the second premolar region.  It sounds straightforward to have the intrusive force at this position, there are two issues with placing miniscrews at this point. 1/ The location may coincide with a premolar root, therefore not feasible to position it in the centre of rotation of the maxilla, 2/ The miniscrew will result in a buccal or palatal vector resulting in undesirable flaring or rolling of the posterior teeth.

6 miniscrews: The gold standard solution to the above is to place two miniscrews anteriorly, two posteriorly in a buccal position, and a further two posteriorly in a palatal position (6 in total, so the calculator app says). The advantage is the vectors produced are favourable to achieve pure intrusion of the maxilla, with the simple application of elastomeric chain to the brackets or archwire. The anterior miniscrews deliver the intrusive force anteriorly, the posterior buccal miniscrews deliver the posterior intrusive force, as well as counter the proclining effect of the anterior miniscrews. The posterior palatal miniscrews deliver a posterior intrusive force, as well as counter the buccal flaring from the buccal miniscrews.

full arch intrusion

4 miniscrews + TPA: It is possible to replace the palatal miniscrews with a TPA to prevent buccal flaring of the posterior teeth, however, the moment and counter-moment within the TPA can result blocking or delay in movement. If a TPA is to be used, a 4-8mm clearance is required from the palatal surface.

To note the delivery of intrusion is slow, and the expected rate of movement is 0.49-0.60mm per month, which equates to 5-7 months El- Namrawy 2019.

Periodontal surgery

Indication: excessive gingiva, short clinical crown
One solution to manage a gummy smile is to remove the offending gingival tissues. However, the decision between the simple removal of the gingiva, gingivectomy, as well as the more evasive removal of crestal bone, crown lengthening, boils down to three factors; the amount of gingival tissue desired to be removed, the anatomical height of sulcular gingiva (free gingiva) present, and the anteroposterior width of the sulcular gingiva.

What difference does the height of the gingiva make?

If the amount of gingiva required to be removed is contained within the height of the sulcular gingiva, then a gingivectomy is the viable option. If, however, the height of gingival removal required is greater than the height of sulcular gingiva, then crown lengthening is required. It sounds strange to remove bone when there are the supracrestal connective tissues, the junctional epithelium and connective tissue (previously termed biological width) between the sulcular gingiva and the crestal bone. However, if the supracrestal connective tissues are reduced surgically, during the healing phase the tissues will reform to their original height, or a persistent area of inflammation will remain, a strange response which is explained by ‘function results in the form’. The junctional epithelium seals the underlying connective tissue, with its fibres of a set length. If the length of the junctional epithelium is reduced, it either reforms, or cannot fulfil its function, and the permeability through the connective tissue creates an area of chronic inflammation.

What difference does the width of the gingiva make?

The sulcular gingiva width is a measure of how robust the sulcular gingiva is through the quantity of keratinsed tissue present. Less than 1.5mm width considered ‘thin’ and greater is considered ‘thick’. The clinical implication is that ‘thin’ gingiva are less robust, and a gingivectomy may result in the greater loss of the sulcular gingiva during the healing process, and an unpredictable appearance. For thin sulcular gingiva, either an apical reposition flap, or crown lengthening is indicated.  A simple method to assess thin or thick gingiva is probing of the sulcular gingiva, a translucent gingiva indicates a thin gingiva, and an opaque gingiva, indicates a thick gingiva

Orthognathic & plastic surgery

 

What is lip repositioning?

Indication: short upper lip / hypermobile upper lip
The principle behind lip repositioning is to reduce the activity of the upper lip elevator muscles by reducing the depth of the upper sulcus. The reduction of the upper sulcus restricts the amount of movement possible. A 3.4 mm Gummy Smile can be corrected with lip repositioning Tawfik 2018, however, there are reports of significant relapse of up to 66%  Dilaver et al therefore recommended the incision made is ‘twice the gingival display’, as well as combined with other approaches to treat Gingival Smile reduction Dilaver 2018.

Can Botox help? (botulinum toxin)

Indication: hypermobile upper lip and short upper lip
Botox induces a temporary paralysis of the upper lip elevator muscles, reducing the activity of a hypermobile upper lip. The use of botox prevents the upper lip from ascending excessively while smiling. The effects of botox are temporary, with a recent systematic review indicating relapse at 6 months Zengiski 2022.

Le Fort I osteotomy

Indication: vertical maxillary excess
Orthognathic surgery through a Le-fort 1 maxillary impaction relocates the maxilla superiorly, in doing so there is a reduction of the Gummy Smile, as well as a reduction of tooth visible at rest. The upper lip annoyingly also relocates superiorly during the impaction, this is due to obicularis muscle inserting at the nasal septum, therefore a degree of overcorrection required for the Le Fort I osteotomy planning of 10% Khojasteh 2022

 

Verdict

This blog has highlighted the methods of managing a Gummy Smile. Although each item has been described in isolation, it is important to note aetiology of a Gummy Smile is usually multifactorial, patients I am afraid, are still not forged from textbooks. Age also plays a factor, the gingival appearance of a 20-year-old female is different to a 40-year-old male (not that any of the authors are approaching such a milestone…) and requires due consideration in planning, both the short term and long-term appearance.

As the only orthodontic mechanism available is orthodontic intrusion, there is a risk of Maslow’s hammer effect, that ’If all you have is a hammer, everything looks like a nail’, which if applied in the wrong case, for example, a short upper lip, runs the risk of creating negative facial aesthetics through increasing the lower incisor display.

The management of a Gummy Smile is a very interesting development in orthodontics, where the malocclusion is no longer the main objective, but orthodontic changes are employed to primarily improve facial aesthetics, an expansion of the term ‘orthodontics’ beyond the origin itself, ‘ortos (straighten) and dontos(teeth).

Addendum: Neither author acknowledges their fast-approaching age milestone, but their lack of gingival display, unfortunately, does.

Contributions

Edited/contents: Farooq Ahmed
Edited: Adith Venugopal
Edited/contents: Khurrum Hussein – periodontist 

Join the discussion