Implant-supported fixed restoration of post-traumatic mandibular defect accompanied with skin grafting: A clinical report
A 54-year-old man was referred to the Department of Prosthodontics at Kyung Hee University to restore the mandibular left missing area. The patient had been in a motor vehicle accident about 20 years ago and had received a number of reconstruction surgeries due to the mandibular traumatic defect of the left side.\nComprehensive intraoral and radiographic examination revealed significant bone loss of the mandibular left side. The floor of the mouth was firm, and lingual vestibule of left side was very shallow. The patient also presented shallow mandibular buccal vestibule and insufficient amount of keratinized tissue. The premolars and molars on the left mandible were missing. Mandibular central, lateral incisor and canine on the left side were shown to be hopeless (, ).\nHard and soft tissue loss was needed to be restored by prosthetic rehabilitation. Several treatment options were suggested and discussed with the patient. Removable dental prosthesis was not considered as a treatment option because of poor tissue condition and lack of support. In spite of alveolar bone loss, inserting dental implants in the alveolar ridge was possible. Also the patient was expecting fixed restoration. Therefore, implant-supported fixed prosthesis was planned. A treatment plan was designed for fabrication of a fixed prosthesis supported by 4 dental implants.\nPrior to implant surgery, a split-thickness skin graft combined with vestibuloplasty at the defect site was planned due to lack of keratinized tissue and shallow vestibule. To improve graft adherence, an intraoral stent was fabricated. Preliminary cast of type III stone (New Plaston; GC Co., Tokyo, Japan) of the mandible was prepared, and the left buccal vestibule was trimmed to the expected depth (). The stent was processed in clear acrylic resin (Vertex Rapid Simplified; Vertex Dental, Zeist, Netherlands), which was extended to the expected vestibular depth ().\nOne month after the extraction of mandibular lateral incisor and canine on the left side, a split-thickness skin graft (12 cm × 5 cm) was harvested from the right upper thigh and secured with 3-0 silk sutured. Then stent was positioned on the grafted site and ligatured into the mandibular anterior teeth to stabilize the stent (). The patient was in loss of posterior support on the left side for the healing period. This allowed better adaptation and healing of the skin graft to the underlying recipient site. The stent was removed 10 days after operation. There were no complications in the graft recipient or donor sites. The interim denture was then relined with tissue conditioning material (Soft-liner; GC Co., Tokyo, Japan).\nThree months after the skin graft, 4 implants (US II, Osstem, Seoul, Korea) with dimensions of 3.3 × 10 mm in the lateral incisor, 4.0 × 10 mm in the first premolar and first molar, and 4.0 × 8 mm in the second molar were placed in the left mandible using a surgical guide to support an implant-supported fixed restoration (). Simultaneously, bone graft (Bio-Oss, Geistlich AG, Wolhusen, Switzerland) was performed. All implants had primary stability at the time of placement. The healing abutments were hand-tightened on all implants. Three months after surgery, the definitive prosthesis was fabricated because none of the implants demonstrated mobility or clinical signs of infection.\nNon-hexed impression copings were connected to the implants and diagnostic irreversible hydrocolloid impression (Alginate; GC Co., Tokyo, Japan) was made, and preliminary cast fabricated. Pick-up type impression copings (ICFR500N, Osstem, Seoul, Korea) were placed on the preliminary cast and splinted with each other with autopolymerizing acrylic resin (GC Pattern Resin, GC America Inc., Alsip, IL, USA) and then sectioned to be reconnected intraorally. The impression copings were connected to the implants and reconnected with autopolymerizing acrylic resin to compensate for polymerization shrinkage. A definitive impression was made using a pick-up impression technique with a custom tray and polyether impression material (Impregum Pentasoft; 3M ESPE, St. Paul, MN, USA).\nA bite block was then fabricated on the definitive cast (Fujirock EP; GC America Inc., Alsip, IL, USA) using pick-up type impression copings (ICFR500N, Osstem, Seoul, Korea) and autopolymerizing acrylic resin (Pattern resin; GC America, Inc., Alsip, IL, USA) (). Maxillomandibular relationship records were obtained using the bite block and silicon occlusal registration material (Geni Bite; Sultan Healthcare, Hackensack, NJ, USA). The definitive casts were then transferred to a semiadjustable articulator (KaVo-PROTARevo 7; KaVo, Biberachan der Riss, Germany).\nNon-hexed temporary abutments (PSM100, Osstem) were connected to the implant analogs (FAM300, FAR300, Osstem) on the definitive cast and full contour wax-up was made. Full contour waxing was then cut back for veneering porcelain and converted into an acrylic resin framework (GC Pattern resin; GC America Inc.) using putty index (Lab Putty; Contene/Whaledent, Inc., Cuyahoga Falls, OH, USA) to be scanned into the computer. This acrylic prosthesis was then copied into zirconia prosthesis (Prettau, Zirkonzahn, South Tyrol-Gais, Italy) with a computer-controlled milling machine (Zirkograph 025 ECO, Zirkozahn).\nAt the next appointment, passive fit of the screw-retained zirconia framework was evaluated intraorally (). Periapical radiograph were made for verifying of the implant-abutment interface. Then the zirconia framework was veneered with feldspathic porcelain (Creation Zi-F; Creation Willi Geller Intl GmbH, Meiningen, Austria). Individual cement-type zirconia crowns (LAVA, 3M ESPE, ST. Paul, MN, USA) were designed in the left premolar and first molar region (). Maxillary first molar was made of conventional screw-type metal ceramic restoration.\nAt the appointment of insertion, the definitive screw retained mandibular zirconia prosthesis was evaluated intraorally, and the abutment screws were tightened to the torque of 35 Ncm. The patient was satisfied with the esthetic and functional end results of the definitive restorations ().\nThe screw access holes were sealed with photopolymerizing provisional material (Fermit; Ivoclar Vivadent, Schann, Liechtenstein) and composite resin (Z100 Restorative; 3M ESPE). The single zirconium oxide crowns were cemented to the framework with provisional cement (Tempbond; Kerr Corporation, Orange, CA, USA).\nThe patient was instructed on maintenance of interproximal gingival health with the use of Super-floss (Oral-B Inc., Iowa City, IA, USA) and Water Jet (Water Pik Inc., Fort Collins, CO, USA). The patient presented satisfactory oral hygiene for the 12 months follow-up period. No clinical complications were observed during the follow-up period ().