Rhabdomyosarcoma is a malignant tumor that is most often seen in children younger than 15 years of age. This pathology is found mainly in the head and neck region. Treatment of rhabdomyosarcoma at early stages of life usually affects the dental and osseous development of children. Because of impaired development, microstomia can arise, making dental treatment more difficult. This article presents a patient with microstomia caused by resection of an embryonal rhabdomyosarcoma in the nasolabial region. The patient was treated with 5 dental implants and fixed hybrid prosthesis in the maxilla and 2 implants supporting an overdenture in the mandible.
Rhabdomyosarcoma (RMS) is a malignant tumor consisting of cells derived from the primitive mesenchyme with varying degrees of striated muscle differentiation and described as the most common soft tissue sarcoma in children younger than 15 years of age.1,2 In all, 35%–40% of RMS occurs in the head and neck region.3,4 Multimodal therapy, consisting of surgery, chemotherapy, and radiotherapy, is a routine procedure for the treatment of patients with RMS.4 RMS affecting the head and neck region usually grows quickly and appears as an enlarged and painless mass. Differentiated diagnosis can be performed by immunohistochemical analysis after an incisional biopsy.5 Early diagnosis of RMS is important because the disease can be controlled and treated in most cases by the combined therapies mentioned previously.6 RMS in the maxillofacial region presents a good prognosis and tends not to invade the central nervous system.4 However, radiotherapy and chemotherapy in the head and neck region of young patients, which are used routinely for the treatment of RMS, can lead to impaired dental and osseous development, loss of taste, xerostomia, mucositis, and a destructive form of dental caries, which, in turn, can initiate the loss of teeth and edentulism afterward. As a result of impaired osseous development, the patient often can be microstomic.3,4,6,7
Endosseous implants serve as a valuable treatment modality for edentulism, especially in jaws with advanced ridge resorption.8 Dental implants offer an alternative that provides major improvement in the long-term prognosis for oral rehabilitation.9 Dental implants provide improved retention and stability and enhanced chewing function and have the potential to preserve substantial bone.10,11 However, patients with moderate to severe bone resorption and thin ridges present additional difficulties because of inadequate bone volume and missing soft tissue support; thus because of mechanical and anatomic drawbacks, implant treatment in the atrophic maxilla represents a challenge,8,12,13 and oral rehabilitation becomes even more complicated with the presence of microstomia.14 Microstomic patients experience considerable limitation in jaw opening and overall jaw mobility.14–16 This limitation in the oral opening makes gaining access to the oral cavity difficult, depending on the severity of microstomia.14 Therefore, traditional approaches for dental restoration should be modified to accommodate microstomia.15,16
Various treatment approaches have been proposed for microstomic patients with or without endosseous implants.14–16 Reduced mouth opening may prevent instruments from safely entering the mouth for insertion of the implants. This is a critical factor in determining whether implant treatment can be provided, and in deciding the number of inserts needed and the best places for insertion.17
This article describes the implant-supported prosthetic treatment of a patient with microstomia and impaired osseous development following resection of RMS and radiotherapy.
linical R eport
A 24-year-old woman (Figure 1) was referred to the Department of Removable Dentures, Faculty of Dentistry, Istanbul University, for prosthetic rehabilitation. Patient history described resection of an embryonal RMS in the nasolabial region, along with chemotherapy and complementary radiotherapy afterwards between the ages of 4 and 6 years. The maxillary and mandibular jaws were hypodeveloped, and microstomia with an oral opening of about 20–25 mm was observed. Most of the maxillary and mandibular teeth had been extracted. The only remaining teeth were maxillary right first and second premolars, maxillary left first molar, mandibular right central and lateral and mandibular left incisors, and first premolar (Figures 2 and 3). All teeth were clinically mobile and carious. A vertical bone grafting procedure had been carried out in the maxilla and had failed before elsewhere. A panoramic radiograph revealed periapical radiolucencies at the mandibular left lateral and first premolar, generalized horizontal alveolar bone loss, and distinct atrophy of the alveolar bone in the maxilla and in molar regions of the mandible (Figure 4).
reliminary E xamination and P lanning
All clinically mobile and carious teeth were extracted. Because bone availability was limited, scanning by dental volumetric tomography (DVT) for planning of the implant positions was performed. Suitable locations were determined by computer-aided diagnostics (Figure 5).
urgical P rocedure
Five dental implants (Straumann, Waldenburg, Switzerland) were placed in the edentulous maxilla using the standard submerged surgical procedure established for the International Team for Implantology (ITI) dental implant system in the regions of maxillary right second molar; second premolar, canine; maxillary left canine; and second premolar (4.1 × 10, 4.1 × 6, 3.3 × 8, 4.1 × 8, 4.1 × 12 mm, respectively). Two 3.3 × 10-mm dental implants (Straumann) were inserted in the interforaminal region of the mandible. Even though mouth opening of the patient was limited and manipulation was difficult, the standard short drills and the screwdriver supplied by the manufacturer were sufficient for implant insertion. Vestibular 2–3-mm fenestrations were repaired with autogeneous graft material. Antimicrobial prophylaxis, started just after the surgery was completed, consisted of 1000 mg oral amoxicillin and 62.5 mg clavulanic acid every 12 hours for 4 days. An anti-inflammatory agent and an antiseptic mouth rinse (diclofenac potassium and 0.2% chlorhexidine gluconate, respectively, both starting immediately postoperatively and continuing every 8 hours for 1 week) were also prescribed.
Three months after surgery, a panoramic radiograph was taken for control, closure screws were removed under local anesthesia, and resonance frequency measurements were made using a previously described method18 with a resonance frequency analyzer (Osstell Mentor, Integration Diagnostics, Savedalen, Sweden). The obtained values confirmed that all implants were stable.19 Appropriate healing caps (Straumann) were screwed to the implants for gingival healing.
rosthodontic P rocedure
After 1 month of gingival healing, because no standard prefabricated impression tray was small enough to enter the oral cavity, preliminary impressions were made without a tray with polyvinylsiloxane impression material (Brecision, Bredent, Senden, Germany). Individual 2-piece sectional trays were prepared on the maxillary and mandibular casts by using a previously described method.16 Open-tray Syn-Octa impression copings (Straumann) were screwed into the maxillary implants, and the maxillary impression was made with a polyether impression material (Impregum Soft, 3M ESPE, St Paul, Minn) by insertion of the tray sections separately. After the set of the impression material, the impression was removed as a single piece (Figure 6). Before removal of the maxillary impression, transfer posts were strengthened with the use of a pattern resin (GC Pattern Resin, GC Dental Products Corp, Tokyo, Japan) to avoid dislocation during unscrewing of the posts. The mandibular impression was made with a zinc oxide–eugenol impression paste (S.S. White Mfg, Gloucester, England) with sections of the mandibular individual tray separately, but tray sections were removed one by one and were connected outside the patient's mouth (Figure 7). Implant analogs (Straumann) were attached to the maxillary impression, and both of the impressions were poured into type IV dental stone (Moldano, Heraus Kulzer, Hanau, Germany). SynOcta 1.5 screw-retained abutments (Straumann) were screwed to the implant analogs, and plastic copings were put on the abutments on the maxillary cast (Figure 8). Wax-up and the chrome-cobalt framework casting (Biosil F, DeguDent GmBH, Germany) were done in the laboratory (Figure 9). After the try-in of the maxillary fixed hybrid framework (Figure 10), a wax rim was prepared upon the framework, and a record base and a wax rim were prepared on the mandibular cast. The occlusal vertical dimension was recorded using previously described methods,20,21 at a reduced dimension to ensure adequate interocclusal space to ease food bolus manipulation. The maxillomandibular relation was recorded into a semiadjustable articulator (IML ARTI S4 IML-Instrumenta Mechanik Labor System GmbH, Wiesloch, Germany) by using a facebow transfer. Two sharp “V”-shaped notches were prepared in the molar areas of the wax rims bilaterally, and the centric relation was recorded with zinc oxide–eugenol impression paste (S.S. White Mfg). In this manner, the maxillary and mandibular wax rims could be removed from the mouth separately and mounted to the articulator. Artificial teeth (Enigma, Davis Schottlander & Davis, Tonawanda, NY) were arranged, tried in, and processed with the maxillary framework, using a heat polymerized acrylic (Meliodent, Bayer UK Ltd, Newbury, UK). The prostheses (Figures 11 and 12) were delivered to the patient with the reinforcement of daily hygiene instructions. After 1 week, when the patient had no complaints with the new mandibular overdenture, ball abutments were screwed to the mandibular implants, and matching ball attachments were used to connect the implants to the mandibular denture using a previously described chairside processing technique.22
During the 1-year follow-up period, the patient was recalled after 1 week and 3 weeks, and thereafter on a 3-monthly basis. The success rate was recorded according to criteria suggested by Albrektsson and colleagues23 as follows: The unattached implant was immobile when tested clinically; no evidence of radiographic peri-implant radiolucency (Figure 13) and no incidence of excessive bone loss around implants were found; no incident of peri-implant inflammation was reported; and persistent and/or irreversible signs and symptoms such as pain, infection, neuropathies, and paresthesia and violation of the mandibular canal were absent. Additionally, no complications associated with the prosthesis were detected, and patient satisfaction was high. The presence of long-term edentulism without the use of a prosthesis may cause phonetic difficulties following denture insertion. However, the use of a fixed maxillary restoration giving palatal freedom provided an advantage, and patients' initial problems were resolved by the time of the 3-week follow-up appointment.
Early loss of teeth can result in esthetic and functional disorders for the patient, who may suffer from psychosocial problems. Reduction or elimination of palatal coverage with maxillary implant-supported prostheses may be perceived as advantageous to patients in providing greater comfort through reduction of tissue coverage.24
The presented patient was treated with a fixed hybrid prosthesis, which was described as the treatment of choice for the atrophic maxilla.8 Because a fixed solution was sought, in light of the young age of the patient, a maxillary detachable prosthesis was preferred owing to the reduced number of maxillary implants. As is well known, maxillary prosthetic restorations on osseointegrated implants are often problematic because of implant location and orientation and the need for lip support. The hybrid prosthesis provides functional and biomechanical stability that is superior to that of a resilient overdenture, along with a cosmetic and phonetic result that often proves superior to that of a full-arch implant-supported fixed bridge.8,25,26 In the mandible, an implant-retained overdenture was preferred to implant-retained fixed prostheses because of severe alveolar atrophy in the mandibular posterior areas, making insertion of additional implants impossible.
The patient was cooperative, and mouth opening was sufficient for insertion of the implants by using short drills supplied by the manufacturer. Because of this, neither special instrumentation nor general anesthesia was needed to gain access to the oral cavity during surgery.
Because of vertical bone grafting procedures carried out that had failed previously elsewhere, the soft tissue in the maxilla was relatively high and mobile. To prevent future soft tissue complications, the tissue level Straumann implant with the smooth collar seemed to be a better choice. On the other hand, it must be emphasized that mouth opening was limited, but interalveolar distance was favorable as the result of bimaxillary crestal atrophy.
Grafting procedures were not considered for this patient because the patient history showed a previous unsuccessful attempt to vertically augment the maxillary alveolar crest, which had caused the patient to suffer considerably. For this reason, no additional grafting, ridge expansion, or sinus floor elevation procedures were attempted. Moreover, because of nasal deviation, pneumatizations of the sinuses were not efficient and DVT images showed sporadic thickening (Figure 5). Without a doubt, reduced implant size constitutes a weakness over the long term, but it is well known that if the first critical year is overcome, implants have a good prognosis for survival.27,28
Fixed maxillary rehabilitation gave the patient palatal freedom and denture stability, self-confidence, and comfortable function, and esthetics improved dramatically.