Case History
A 45-year-old woman with microstomia was referred to the Prosthodontic Department for receiving complete denture for both maxillary and mandibular arches in June 2018. She had scar tissues, burned face and deformed hands caused by burning in an accident. The maximum oral opening was approximately 20 mm in height and 35 mm in width, with tight and inflexible labial tissues. The mandibular alveolar ridge was resorbed moderately. After discussion and offering various treatment options, the patient agreed to go under surgical enlargement of the oral aperture and then fabrication of conventional complete denture. The preliminary impression making was started after four weeks of commissuroplasty. Petroleum jelly was used on the commissures. The preliminary mandibular impression was made with the smallest edentulous stock tray and irreversible hydrocolloid (Chromogel alginate, Marlic medical industeris Co, Iran). The tray inserted by 90˚ rotation while an intraoral mirror was used for retracting the lips as much as possible. For the preliminary maxillary impression, stock trays with various sizes and shapes were examined. However, inserting them was not possible due to the limited mouth opening. Therefore, digital maxillary impression was taken using an intraoral scanner (TRIOS 3 Basic; 3shape, Copenhagen, Denmark). The retraction of lip and cheek and maxillary vestibular area stretching were performed by an intraoral scanner tip in order to successfully scan the soft tissues. The mandibular impression was poured in type II dental stone (Dental Plaster, Pars Dandan, Iran). The scan data were then converted to the standard tessellation language (STL) file and transported to 3D printing device (Digi Dent Plus, Mobtakeran mecathronic ARK Co, Iran) to print the model with resin (Freeprint model 2.0, Detax, Germany) with 25-100 μm accuracy (Figure 1). A sectional custom maxillary tray was fabricated using the autopolymerizing acrylic resin (Acrylic acropars, Marlic medical industeris Co, Iran) on the printed model. Two sections of the tray were unequal with the right section being larger, cross the midline and extend to the left buccal frenum. Moreover, it had specified butt joint border on the outer surface and magnet attachment. However, the smaller tray section had specified butt joint border on the intaglio surface and magnet attachment on the outer side to be attached to the first one. In addition, a conventional custom mandibular tray was fabricated with the same acrylic resin. Tray borders were trimmed in order to have 2 mm space above the vestibular depth for the border molding.
labial and buccal vestibule, frena and postpalatal seal areas were functionally recorded with modeling plastic impression compound (PERI Compound; GC, Japan) (Figure 2). The final impression was made with zinc-oxide Eugenol-free impression paste (ZOE) (Cavex outline; Cavex , Netherland). The impression paste was initially placed in the larger tray segment and inserted in the mouth. Then, the other tray segment with the impression paste placed over the magnets to ensure locking of the 2 tray segments. After the impression material set, the tray segments were removed from the mouth one by one and fixed together outside (Figure 3). The mandibular tray border was molded with thermoplastic sticks (Isofunctional, GC, Japan) and definitive impressions were made with ZOE (Cavex outline; Cavex , Netherland). Final impressions were boxed and poured using ADA type III dental stone (Dental Plaster, Pars Dandan, Iran). The maxillary record base and occlusal rims prepared in two pieces as the right and left segments being attached to each other by magnet. They were then placed in mouth and adjusted according to aesthetic and phonetic. The maxillomandibular relationship was recorded in centric relation and definitive casts were mounted on a semi-adjustable articulator (Hanau H2; Whip Mix Corp). The semi-anatomic artificial teeth (A1,B13 Finex , Beta dent, Iran) were arranged with bilateral balanced occlusion. Esthetic, phonetic and occlusion were evaluated in try-in session. The important point is that the patient could not assemble the segments because of hands deformity, therefore integrated maxillary denture was planned for the final prostheses (Figure 4). At the delivery appointment, denture base extensions were evaluated, excessive pressure of the intaglio surface was relieved and the occlusion was adjusted to derive simultaneous tooth contact in centric and eccentric positions. The prosthesis placement was demonstrated to the patient and delivered as well. The hygienic recommendations were explained to the patient as well. The patient had no difficulties using the dentures and satisfactory results were obtained during a 5-year follow-up period. The compatibility of the intaglio surface of the denture with the underlying tissue and occlusion was checked, annually. Little discoloration was seen in the artificial teeth.