Introduction
Microstomia, defined as an abnormally small oral orifice, can occur as a result of trauma including facial tissues injuries, animal bites, electrical and thermal lesions and chemical burns (1, 2). This condition can also arise from genetic disorders and diseases such as Plummer-Vinson syndrome and the collagen group of diseases including submucousal fibrosis and scleroderma (3) or surgical treatment for orofacial cancers and reconstruction of lip defects(4). The main problems due to microstomia can be of functional (speech, nutrition and hygiene) or esthetic (due to asymmetric lip placement) groups. Many treatment options including the surgical, nonsurgical and a combination of these two are available to cope with this abnormality. The aim of treatment is not only providing well-functioning lips with increased mouth opening and esthetic improvement, but also providing a stable and long-lasting result (5). Some techniques such as surgery and denture design modification have been recommended for problem management associated with providing dental prostheses for edentulous patients with microstomia(6). Making high-quality preliminary impressions which record all anatomic landmarks is mandatory for the successful complete denture treatment. During the impression procedures in patients with microstomia, wide opening of the mouth is required for the proper tray insertion and alignment, but this is impossible (7). Preliminary impressions from patients with microstomia have been made using various tray modifications such as modified stock trays, flexible trays or without conventional ones using an initial poly vinyl-siloxane (PVS) impression. Although these techniques have been successfully implemented, the proper method for making a preliminary impression has not been determined. Nowadays, using computer-aided technologies make possible to design and fabricate complete denture. Making impressions with intraoral scanners could eliminate tray selection and adaptation, infection transmission from patients and impressions transference to the laboratory(8). However, several factors such as saliva reflection and dynamic movements of soft tissues make the digital impression from edentulous arch difficult. Making final impression in these patients needs alternative techniques like the sectional impression trays that has been recommended that trays should be cut into two unequal sections so that the labial frenum is recorded accurately in the impressions (9). The two halves of the tray could be joined using LEGO building blocks, fins in the handle, metal pins and burs(10). Similarly, removable complete and partial dentures have employed the sectional or collapsible designs to retain them in an unfolded position. The corresponding examples include the insertion of pins, use of a locking tool, latching a swing-lock assembly and locking the denture segments with magnets or attachments and also using flexible denture materials (9). It is impossible to make a collapsible maxillary denture consisting of only 2 sections, because of the palatal vault. Therefore, a third section is usually used for this purpose (4).
The aim of this clinical report is to present the prosthetic treatment applied to an edentulous patient with microstomia using an intraoral scanner for preliminary impression and fabricating complete removable prostheses.