Mouth opening

Mouth opening & access for treatment interventions

Most patients’ mouth opening readily permits access for routine prosthodontic and surgical treatment interventions. Limited mouth opening or microstomia is encountered in patients exposed to sclerodermia, diffuse systemic sclerosis, oro-facial trauma or surgical resections for neoplastic disease, temporo-mandibular disorder (TMD). The latter’s resultant scarring and tissue contracture, together with an accompanying lack of underlying bony support and tissue edema, restricts the mouth opening and renders surgical and dental treatment difficult.

One cannot provide a lower limit for a mouth opening which would prevent from choosing an implant-based rehabilitation. The labial orientation of the implant axis, subsequently compensated by angulated abutments or superstructures, can provide a solution to the access difficulties.

Soft tissue healing and/or scarring can take years to reach a stable status. Meanwhile efforts to achieve a provisional and also definitive tissue support and improve esthetics with a prosthesis must be considered prior to further treatment planning.

Surgical resections or trauma to the oral cavity structures can also lead to loss in vertical dimension, reduced opening of the mandible plus altered mandibular motion. Associated trismus leading to fibrosis and scarring is often the main cause. Radiotherapy can also cause perioral tissue fibrosis. As the treated areas heal, manual mouth opening exercises and stretching may improve the range of mandibular motion and vertical opening. A decreased vertical opening presents with significant challenges for the oral hygiene maintenance, food bolus manipulation and surgical and prosthetic management.

Patients with limited mouth openings are usually readily managed via gentle and scrupulous handling of circum-oral soft tissues and use of smaller sized-instruments as designed for pediatric patients. Dentures with a flexible denture base material can be discussed if this treatment is the best option.

Implant therapy offers possibilities for matching a limited mouth opening with a more convenient and controlled prosthesis access design. Via customized treatment designs retention and stability can be guaranteed. This is also the time to check whether intubation can be safely performed if general anesthesia is planned for the implant-based therapy.