Polymethyl methacrylate-based bone cement using a prototype for gingival smile: A case report.

Abstract

Background: The treatment of gummy smile (GS) with polymethyl methacrylate (PMMA)-based implants is suggested in specific cases such as those in which there is a lack of lip support due to a marked depression of the anterior maxillary process; however, it can be associated with certain complications related to the material and the surgical approach.

Methods: A patient with a GS of combined etiology was treated with clinical crown lengthening and lip repositioning surgery with placement of a PMMA-based bone cement implant to fill the subnasal depression. Surgical planning was performed using a 3-dimension resin-printed model to achieve an optimal fit of the PMMA implant to the geometry of the bone defect and to avoid any damage related to heat exposure from the polymerization process and any possible damage to the tooth roots with the fixation screws. In addition, the use of an antibiotic cement can help prevent any possible infection.

Results: The patient reported edema and mild pain. After 5 months an increase in the length of the dental crowns, a reduction of the exposed gingiva to 1 mm and a new support of the upper lip were clinically observed. Cone-beam computed tomography showed proper PMMA implant fit.

Conclusions: The use of PMMA-based bone cement appears to be an effective technique for the treatment of cases of GS associated with hypermobile upper lip and maxillary subnasal depression. The use of a printed resin model avoids complications during curing of the material, such as high exothermic reactions and associated infections.

Key points: Identification of the etiologic factors of gummy smile is fundamental to the treatment of gummy smile. Once the diagnosis is established, therapy focuses on the treatment of these factors, which may be single or combined. The use of a PMMA-based bone cement implant in conjunction with clinical crown lengthening surgery is an effective treatment option for the management of EGD related to upper lip hypermobility, passive altered eruption and, maxillary subnasal depression. A possible clinical dilemma could arise when considering some complications associated with the use of PMMA implants such as allergies or infections. However, the use of a 3D printed resin model facilitates handling and fitting outside the mouth by eliminating heat exposure from the polymerization of the cement and to avoid any possible damage to the tooth roots with the fixation screws. In addition, the use of an antibiotic cement can help prevent any possible infection.

Plain language summary: The treatment of gummy smile will depend on its etiological factor. In some cases of combined etiology, the use of polymethyl methacrylate (PMMA) implants has been suggested, such as those in which there is a lack of lip support due to a marked depression of the maxillary anterior process; however, the use of PMMA can be associated with certain complications such as allergies and infections. To avoid this, surgical planning was performed using a 3D resin-printed model to achieve an optimal fit of the PMMA implant to the geometry of the bone defect and to avoid any complications such as damage related to the heat exposure of the polymerization process and any possible damage to the dental roots with the fixation screws, obtaining satisfactory results after 5 months.