PMC5624144_01
Patient with limited mouth opening induced by radiotherapy.
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fig1
A 60-year-old male patient with trismus induced by RT presented to the Department of Prosthodontics of Istanbul University for prosthodontic treatment of a total  maxillary defect and edentulous mandibular arch with a limited maximal mouth opening measuring approximately 25 mm (Figure 1).  The level of oral hygiene was poor and the patient had no prior experience with a maxillary or mandibular removable denture.
Mini anchors and ball abutment housings for sectional mandibular denture.
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fig2
AG, Koblach, Austria). At the trial stage, artificial teeth (Optodent, Bayer, Leverkusen, Germany) were arranged with posterior balancing ramps to achieve eccentric balanced occlusion and the dentures were completed conventionally in one piece with heat-polymerized polymethyl methacrylate (PMMA) (Meliodent; Bayer UK Ltd, Newbury, UK). At the delivery appointment, because of the limited mouth opening and the height of the posterior mandibular alveolar ridge, it was impossible for the patient to place the mandibular denture in the mouth after insertion of the maxillary obturator prosthesis; thus, a mandibular sectional denture was designed in two pieces with a locking mechanism, by using mini anchor and ball abutment housing with cap (Figure 2).  
Six points were marked on the definitive cast and denture for cutting guidelines.
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fig3A
Before sectioning the mandibular denture, six points were marked on the vestibular and lingual outline of the definitive cast and denture to obtain a section guideline, and the denture was sectioned along this guideline with a thin cutting disc (Bur no: 806.104.355.514.190.X; Finzler, Schrock and Kimmel GmbH, Bad Ems, Germany) (Figure 3A and Figure 3B).
Denture was sectioned with cutting disc.
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fig3B
An irreversible hydrocolloid was used for impression of the inner surface of the upper segment of the denture, and impression material was poured in dental stone to obtain a stone index  (Figure 4A and Figure 4B). This stone index was used for recovering the loss of PMMA  with autopolymerizing acrylic resin during the separation process (Figure 4C).       
Inner surface of the upper segment impression was made with irreversible hydrocolloid.
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fig4A
Two hollow cavities were made on the canine regions and mini anchors were placed in these cavities with autopolymerizing acrylic resin (Figure 5A). KG, Hagen, Germany) were attached on mini anchors, and the positions of abutment housings in the upper segment of the mandibular denture were marked by using a spirit-based pen (Figure 5B). Autopolymerizing acrylic resin was then polymerized and the two segment mandibular denture was completed (Figure 5C and Figure 5D).
Stone index was obtained.
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fig4B
The lower segments were first inserted into the mouth; then the upper segment was attached on the lower segment (Figure 6A and Figure 6B).
Lower segment was recovered with autopolymerizing acrylic resin by using stone index.
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fig4C
The patient stated his satisfaction with this method of insertion (Figure 7).