Prosthodontic management of edentulous patient with limited oral access using implant-supported prostheses: A clinical report Ansgar C. Cheng, BDS, MS,a Loh Kwok-Seng, MBBS,b Alvin G. Wee, BDS, MS, MPH,c and Neo Tee-Khin, BDS, MSd National University of Singapore, Singapore; College of Dentistry, Ohio State University, Columbus, Ohio Limited oral access presents a unique challenge to prosthodontic treatment. An edentulous patient who developed microstomia after a maxillary lip resection is presented. The clinical procedure and the rationale for the treatment approach using implanted-supported overdentures are discussed. (J Prosthet Dent 2006;96:1-6.) A limitation in mobility of the mandible that results from tonic contracture of the masticatory muscles is known as mandibular trismus.1 Patients with this condition may experience a significant limitation of jaw opening and overall jaw immobility. A limited oral opening can be caused by head and neck radiation,2-6 surgically treated head and neck tumors,6 reconstructive lip surgeries,7 reflex spasm,8 connective tissue disease,9,10 fibrosis of masticatory muscles,11 facial burns,12 and microinvasion of the muscles of mastication.8,13 When a lip defect is reconstructed, the continuity of the oral aperture is restored. However, because the net loss of soft tissue from the resected lip is not replenished in such a procedure, microstomia is inevitable. This clinical condition introduces significant challenges for regular food intake and regular oral hygiene maintenance. In addition, having a limited oral opening can be a problem for patients who require dental treatment.14,15 The use of standard complete-arch stock impression trays may be impossible, and this may preclude successful dental prosthesis fabrication and prosthesis use. Management of the problems associated with providing dental prostheses for patients with microstomia has not been well reported,15 although the management techniques previously described include surgery8,16 and modification of denture designs.15,17,18 The fabrication of a removable partial denture requires an accurate impression of the denture-bearing area and a record of appropriate anatomic landmarks.19,20 Detailed preliminary impressions and accurate diagnostic casts are crucial for surveys, denture design, development of custom trays, and definitive impressions. Conventionally, a Adjunct Associate Professor, Graduate Prosthodontics, National University of Singapore. b Assistant Professor, Otolaryngology, Faculty of Medicine, National University of Singapore. c Associate Professor, Section of Restorative Dentistry, Prosthodontics and Endodontics, College of Dentistry, Ohio State University. d Adjunct Assistant Professor, Restorative Dentistry, National University of Singapore. JULY 2006 stock trays are used to make preliminary impressions. Even though stock impression trays come in various designs, sizes, shapes, and materials, the insertion of stock trays may be impossible if there is a severe limitation in the oral opening. Modification of a stock impression tray may further reduce its size and ease its insertion into the oral cavity. Clinically, an impression can be made as long as the maximum vertical opening provides an interarch space that is greater than the vertical height of an impression tray, and the oral opening can be stretched to a width that is equal to or greater than the width of an impression tray. For most patients, successful removal and insertion of impressions requires a reasonable degree of flexibility of facial and lip soft tissues. In situations in which scar tissue formation has decreased the flexibility of the lips, insertion and removal of stock impression trays may not be possible. Border molding materials such as modeling plastic impression compound,20,21 vinyl polysiloxane,22,23 and polyether24-26 impression materials are used in removable prosthodontics. Polymeric border molding materials have several advantages over modeling plastic impression compound. Polymeric border molding materials allow: (1) elimination of the need for multiple insertions and removal to border mold the impression tray, (2) ease of manipulation, (3) elimination of the water bath, and (4) superior accuracy.27 The treatment of the edentulous mandible using an endosseous implant-supported overdenture is a relatively simple, predictable, and widely accepted treatment option.28-31 It has been shown that implant-supported overdentures improve psychological well-being32 and quality of life.33 The implant-supported overdenture prosthesis offers easy access for oral hygiene maintenance and the provision of a denture flange to augment missing dental alveolus.34 Overdenture prostheses require a certain amount of space for adequate denture base thickness and housing the prosthetic components. Preprosthetic assessment of the available interocclusal distance is crucial for the development of the definitive prosthesis. Patients THE JOURNAL OF PROSTHETIC DENTISTRY 1 THE JOURNAL OF PROSTHETIC DENTISTRY CHENG ET AL Fig. 1. Frontal view of reconstructed maxillary lip defect. Fig. 2. Frontal view of opened oral cavity, with regular dental mirror (diameter of 22 mm) for comparison. Estimated diameter of oral opening was less than 28 mm. with minimally resorbed edentulous alveolar ridges may have insufficient space for an implant-supported overdenture.35 Limited interarch space may also limit the choice of prosthetic components. Surgical reduction of the alveolar bone and the use of internal connection implants may overcome the space limitation.36 The purpose of this article is to describe the clinical management of a patient with reduced perimeter of the oral cavity and severe trismus using implant-supported removable prostheses. The implant-supported denture prostheses restored mastication, speech, dental articulation, anterior oral seal, and lip support. with limited bone width for implant placement except at the premolar areas. There was remarkable limitation in the oral opening and reduced tissue flexibility. The diameter of the oral opening was estimated to be less than 28 mm. Making an impression of the maxillary and mandibular alveolus using stock impression trays was impossible due to limited oral access and reduced lip flexibility. An additional surgical procedure was not planned to improve the oral opening. Endosseous implant tissue-bar retained overdentures with modified prosthodontic procedures were planned. Four endosseous implants were planned for the maxilla and 2 implants were planned for the mandible. Due to the limited oral access, placement of dental implants was performed without using a surgical template. Four endosseous implants with internal connection (Certain; 3i Implant Innovations Inc, Palm Beach Gardens, Fla) were placed in the maxillary premolar areas. Two endosseous implants (Certain; 3i Implants Innovations Inc) were placed in the mandibular canine regions (Fig. 3). No prosthesis was used during the healing period. The postoperative healing was uneventful. The implants were exposed approximately 8 months after implant placement. The anterior implants bilaterally in the maxilla failed. The 2 osseointegrated maxillary implants were determined to be located too far posteriorly, and this rendered retentive component connection difficult. They were left with 4-mm healing abutments (3i Implant Innovations Inc) and served as conventional overdenture abutments without any retentive element to simplify the prosthodontic treatment procedures. Putty-type impression material (Aquasil; Dentsply Intl, York, Pa) was manually dispensed intraorally to serve as custom trays for diagnostic maxillary and mandibular impressions. The impression putty was soft during initial insertion. Once the impression putty was placed intraorally, it was carefully positioned onto CLINICAL REPORT A 71-year-old Chinese woman was referred for prosthodontic assessment of an acquired maxillary defect. A review of her medical history showed that she had type-2 diabetes. Her maxillary lip, columella, and nasal septum were resected due to a necrotizing fascitis. The resulting maxillary lip defect was reconstructed using a Karapandzic flap.37 The adjacent soft tissue from the nasal-labial fold was rotated medially and inferiorly to reconstruct the maxillary lip defect37 (Fig. 1). The overall perimeter of the oral cavity was reduced significantly. Visual inspection of her lateral facial profile revealed that the mandibular arch was approximately 10 mm anterior to the maxillary arch (Fig. 2). The clinical examination revealed a completely edentulous oral cavity with moderate alveolus resorption. Severe bony resorption was noted in the anterior maxilla. The surgical procedure occurred approximately 5 months before her prosthodontic evaluation. Postsurgically, the patient’s diabetic condition was under control with medication and dietary modifications. The patient was not using any type of dental prosthesis. A panoramic radiograph and computerized tomographic scan of the maxilla revealed type 4 bone,38 2 VOLUME 96 NUMBER 1 CHENG ET AL THE JOURNAL OF PROSTHETIC DENTISTRY Fig. 3. Panoramic radiographic view immediately after implant placement. At stage 2 surgery, 1 implant on each side of maxilla failed to osseointegrate. Fig. 4. Definitive maxillary (A) and mandibular (B) impressions made of vinyl polysiloxane material in acrylic resin custom trays. Fig. 5. Matrix components of attachments attached to heatpolymerized denture base using autopolymerized acrylic resin. the denture-bearing areas, and the impression material was border molded to the appropriate contour. The impression putty custom tray was removed after polymerization. It was then inspected for accuracy, and additional impression putty was added to the tray to establish the appropriate extension as needed. The vinyl polysiloxane putty impression tray was removed, and the excess bulk was trimmed off. Medium-viscosity impression material (Express; 3M ESPE, St Paul, Minn) was added onto the silicone custom trays and inserted intraorally. The diagnostic impressions were removed after the impression material was fully polymerized and visually inspected for accuracy. The maxillary and mandibular diagnostic impressions were poured using American Dental Association (ADA) type V dental stone (Die-Keen; Heraeus Kulzer, Hanau, Germany). Extension of the definitive impression custom trays was outlined on the diagnostic casts. Custom JULY 2006 mandibular and maxillary impression trays were made using autopolymerizing acrylic resin (Formatray; Kerr, Orange, Calif). During the definitive impression appointment, the fit of the custom trays was verified. Border molding was accomplished by applying impression putty (Aquasil; Dentsply Intl) onto the impression tray border, which was then inserted and border molded. Upon polymerization of the putty, the border-molded impression trays were withdrawn and inspected for accuracy. Additional putty was added to any deficient areas. Tray adhesive (Tray adhesive; Dentsply Intl) was applied to the intaglio surface and borders of the impression trays. A wash impression was made using medium-viscosity vinyl polysiloxane (Express; 3M ESPE) (Fig. 4). Final casts were poured in ADA type V dental stone (Die-Keen; Heraeus Kulzer). A wax pattern of the definitive denture bases was made on the final casts, and the denture bases were made using heat-polymerized acrylic resin (Lucitone 199; Dentsply Intl). Low-profile resilient attachments (Locator; Zest Anchors, Escondido, Calif) were selected. The matrix/patrix abutment portions of the attachment were connected to the implants. The attachment matrices were intraorally attached to the heat-polymerized denture base using 3 THE JOURNAL OF PROSTHETIC DENTISTRY CHENG ET AL Fig. 7. Completed wax arrangement of artificial teeth. Note class 3 incisal relationship. Fig. 6. Intaglio surface of maxillary (A) and mandibular (B) denture base. Black processing analogs of matrix attachments were eventually replaced during prosthesis insertion. autopolymerized acrylic resin (Quick-resin; Shofu, Japan) (Figs. 5 and 6). A centric relation record was obtained with the definitive bases and wax occlusion rims (NeoWax; Dentsply Intl) using an interocclusal registration material (Regisil; Dentsply Intl). The occlusal vertical dimension was recorded at a reduced dimension to ensure sufficient interocclusal space to ease food bolus manipulation. The casts were mounted in a semiadjustable articulator with a facebow record (Hanau Wide-vue; Teledyne Waterpik, Fort Collins, Colo) and the centric relation record. Zero-degree artificial teeth (Dentacryl SA; Dentsply Intl) were arranged (Fig. 7). The denture teeth were processed on the definitive denture bases using heat-polymerized acrylic resin (Lucitone 199; Dentsply Intl). At the insertion appointment, denture base adjustments were performed with a pressure indicating paste (Pressure Indicating Paste; Mizzy Inc, Cherry Hill, NJ). The patient was instructed in the insertion and removal of the prostheses (Fig. 8). Daily oral hygiene instruction was reinforced. After the initial period of postinsertion adjustment, follow-up appointments were scheduled every 6 months. 4 Fig. 8. Definitive prostheses. DISCUSSION The selection of the lip reconstruction option is based on the size, depth, and location of the defect. Full-thickness defects that are less than half the surface area of the lip are usually closed primarily.37 Defects that span between half and two thirds of the surface area of either lip are commonly closed by means of the 2-stage Abbe-Estlander flap technique.37 This technique results in lip-switching flaps, which commonly lead to progressive microstomia because of the loss of neural stimulation. The Karapandzic flap technique involves the creation of circumoral incisions in the nasolabial folds. The incisions are made close to the intraoral mucosa. The orbicularis oris muscle is freed from the other perioral muscles to enhance advancement of the flap. Immediate function may be restored because the neurovascular pedicle is preserved. In the situation presented, the reconstructed maxillary lip had altered the neutral zone of the maxillary arch significantly. Maxillomandibular relation records VOLUME 96 NUMBER 1 CHENG ET AL and mounting of the casts in the articulator revealed a class 3 skeletal pattern. Due to the skeletal pattern, zero-degree denture teeth were chosen for the development of the occlusion. The development of the maxillary lip support was performed to minimize violation of the neutral zone. In the treatment described, a semi-rigid material was used as an impression tray for the diagnostic impressions. Vinyl polysiloxane was used because of its rigidity and the ease of dispensing and mixing it. Because the material was hand-dispensed intraorally, the difficulties of stock impression tray insertion for a patient with microstomia were eliminated. This material offers a reasonable amount of elasticity and can be removed even though it may be slightly oversized with respect to the limited oral access. Surgical templates are helpful in accurate placement of endosseous implants. However, use of a surgical template requires unhindered oral access. Surgical templates were not used for this patient due to limited oral opening. Placement of implants in the mandibular anterior area was predictable due to relatively better visual and manual access. Surgical bony augmentation in the maxilla, such as a sinus-lift procedure, was not performed due to limited access. As a result, placement of implants in the maxilla was limited to the maxillary premolar areas due to limitation in bone volume in the anterior maxilla and compromised surgical access. A history of diabetes and a type-4 bone bed are considered potential risk factors in endosseous implant success. As long as the diabetic condition is under control, studies have shown promising results in diabetic patients with implant-supported removable overdentures.39,40 In this report, the maxillary bone bed of the patient was diagnosed as type-4 bone. Two out of the 4 implants placed in the maxilla failed to integrate, which resulted in a success rate of only 50% in the maxilla. If all 4 implants placed were osseointegrated with a favorable antero-posterior spread, a retentive bar could be constructed for prosthesis retention. Even though no retentive element was connected to the maxillary implants due to limited oral access, the implants served as conventional overdenture abutments to provide additional denture support and assist in maintaining bone level and reduce alveolar resorption. In the anterior mandible, both implants integrated without complications. They were crucial in providing retention for the mandibular complete overdenture prosthesis. Two overdenture attachments were selected due to their ease of manipulation and small size. Definitive impressions of the maxilla and mandible were made without placement of any implant impression coping on the osseointegrated implants. This facilitated impression making in an oral cavity with limited access. A heat-polymerized permanent denture base was used for the remainder of the clinical procedures, and the JULY 2006 THE JOURNAL OF PROSTHETIC DENTISTRY mandibular attachments were attached to the definitive denture base using autopolymerized acrylic resin. 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CHENG 3 MOUNT ELIZABETH, #08-10 SINGAPORE 228510 FAX: 65-67336032 E-MAIL: ansgar_cheng@hotmail.com 0022-3913/$32.00 Copyright Ó 2006 by The Editorial Council of The Journal of Prosthetic Dentistry. doi:10.1016/j.prosdent.2006.04.010 VOLUME 96 NUMBER 1