3D Printed Polymethylmethacrylate Versus Polyether Ether Ketone Implant for Management of Gummy Smile Through VISTA Technique: A Randomized Clinical Study

A smile plays an important role in determining a person's initial impression and its assessment has become integral to clinical evaluation owing to how appealing a smile could be among people. A gingival smile, gummy smile or high smile line is an aesthetic concern with 10-12% prevalence among dental patients mainly in women and is diagnosed when a patient shows ≥3 mm of free gingiva.

A gummy smile may result from a single cause but is more commonly found to be the result of an interplay of multiple factors and identifying the causative factor is the basis for its treatment. It may be broadly caused by dentoalveolar discrepancies or non-dentoalveolar discrepancies. Dentoalveolar discrepancies include short clinical crowns, altered passive eruption and gingival hypertrophy/hyperplasia. These discrepancies can be improved by restorative and periodontal approaches. Non-dentoalveolar discrepancies include hyperactive upper lip, short, or incompetent upper lip and vertical maxillary excess. Orthognathic surgery, lip repositioning (LRT), orthodontic treatment, and Botox injections are the main treatment modalities typically employed for treating thesis conditions.

LRT, first described by Kostianovsky and Rubinstein in 1976, has shown excellent efficacy in treating gummy smile, showing an average reduction of 2.71 to 3.4 mm at 6 months of follow-up in previous systematic reviews. However, the traditional technique has reported different partial or complete degrees of relapse. Therefore, different modifications have been developed to improve the predictability and stability of the technique and reduce morbidity and complications.

Most modifications reported in the last 5 years aim to provide improved stability of outcome by introducing techniques that eliminate or restrict the function of the muscles responsible for raising the upper lip during smile or that alter/restrict the hypermobility of lip movement. Some of these techniques include the use of adjuvants such as botulinum toxin (BOTOX).

Injecting overactive muscles with measured amount of botulinum toxin results in a reduction of muscle activity, relaxation of the lip muscles and decreasing upward pull on the lip. The improvement achieved is almost immediate but remains only for a period of 3-6 months, before slowly fading. This relatively short duration is the major disadvantage of the technique, that require constant reapplication and the effects of long-term use of Botox have not been adequately researched