Restoration of an Acquired Mandibular Defect Secondary to a Neoplasm Excision
Robert Schneider, DDS, MS
The use of dental implants for treatment of partial edentulism has become common in today’s prosthodontic and surgical practices around the world.1-7 Today’s implant systems present very good long-term success levels as well as several advantages over the traditional fixed and removable treatment alternatives in many cases.2,3 The treatment of patients with neoplasms that have been excised and restored with dental implants is a very challenging aspect of surgical and prosthodontic practices.8 Current developments in dental materials and techniques can allow the restorative dentist and dental technician to restore these conditions to improve the long-term function and esthetics for the patient.
In this article, the treatment of a 32-year-old woman with a partially resected and reconstructed anterior mandible (resulting from an aggressive, central giant-cell granuloma) and restored with the SPI® system (Thommen Medical, Cleveland, OH) will be presented.
Patients who have had resections of the anterior mandible may face several problems from potential permanent numbness/anesthesia as a result of the resection of the nerves that supply feeling to the lower lip and gingiva, loss of facial support for the contours of the lower lip, and a loss of function and possibly phonetic difficulties from the loss of multiple teeth. The restoration of such large defects may be best treated, when possible, with fixed prostheses rather than a removable prosthesis.
Approximately 2 years before presentation, the patient had noted some drifting and tooth movement in her anterior mandible (Figure 1 and Figure 2). Examination and biopsy by the oral and maxillofacial surgeon revealed an aggressive, central giant-cell granuloma. The routine treatment is wide excision and reconstruction with a cortical-cancellous hip graft and skin graft. The lesion was excised with wide margins from teeth Nos. 22 to 28 and reconstructed with a hip graft to the defect area (Figure 3).
After several months of healing the patient presented to the Hospital Dentistry Institute (Iowa City, IA) for prosthodontic and surgical treatment. She was not wearing a replacement prosthesis and had not used one since the resection and reconstruction surgery. The alveolar ridge appeared thin intraorally but on palpation it was determined that there was very adequate width and height of the alveolus to place dental implants for a definitive fixed restoration. Her occlusion was very stable, there were no other medical considerations, and her oral hygiene was excellent (Figure 4).
Several years earlier the patient had completed orthodontic therapy uneventfully and had retained her posttreatment casts and also had in her possession a clear thermoplastic index that was used as a provisional retainer during her treatment. This would prove very helpful in the initial diagnosis and treatment planning for tooth and implant placement.
Using current, mounted diagnostic casts, the previous thermoplastic retainer was used in a diagnostic waxing procedure to determine the previous tooth placement for optimal development of esthetics and phonetics (Figure 5; Figure 6; Figure 7). Through the use of the wax-up, the number and position of the dental implants could be determined and would assist in the fabrication of the restrictive surgical guide (Figure 8A and Figure 8B). After discussion with the patient and the surgeon it was decided that four Thommen SPI 5-mm element implants could be strategically and accurately placed to facilitate the fabrication of a screw-retained fixed prosthesis.
This system was used because the author’s surgical team is very comfortable with it in large full/partial arch reconstructions. There is a polished collar on the implant and the team did not desire to place a “bone” level implant to help ensure soft tissue health, maintain adequate biologic width, and maintain the existing bone height. Additionally, the restoring prosthodontist requested this system because of the available restorative components/abutments for the fabrication of a laser-welded titanium framework that has been very reliable, predictable, and worked well in previous similar situations.
At surgery, the graft-stabilizing screws were removed and the surgical guide was used for accurate implant placement. Four implants were placed uneventfully and 3.2-mm healing caps were placed. No provisional restoration was placed. The 4-month healing period was uneventful.
After the prescribed healing period, the final impression was made at the implant level with an open-tray technique (Figure 9 and Figure 10). The laboratory analogs for the implant replicas were placed in the final impression and it was poured in a high-strength, low-expansion die stone (ResinRock, Whip Mix Corporation, Louisville, KY) (Figure 11). The maxillary and mandibular casts were attached to a semi-adjustable articulator through the use of a facebow transfer and centric-relation records. The SPI RETAIN abutment (Thommen Medical) was used because there is a titanium bar coping that could be laser-welded to develop the substructure for the planned acrylic resin fixed partial denture. Additionally, this abutment allows for the prosthesis to be screw-retained, making removal, if necessary in the future, much easier than a cemented restoration. The laser-welded titanium framework was completed with the assistance of the previously mentioned thermoplastic matrix made from the patient’s diagnostic casts presurgery (Figure 12A; Figure 12B; Figure 12C). Note the ability to achieve adequate facial/lingual and incisal/gingival height on the connectors (Figure 13A and Figure 13B). Some of the advantages of titanium laser-welded frameworks are biocompatibility, strength, and passive fit.9-15
At the author’s request, the framework was returned for try-in to ensure passive fit before final waxing and processing of the prosthesis. The patient returned for the try-in appointment and the framework was verified as having a passive fit on the abutments (Figure 14A and Figure 14B). The prosthetic teeth can then be arranged according to the previous template and tried in if desired to confirm esthetics and phonetics. The framework was masked with a pink opaque and processed in a characterized high-impact, heat-polymerized, acrylic resin (Figure 15A ; Figure 15A ; Figure 15C).
At the prosthesis delivery appointment the cover screws were removed (note the excellent soft tissue health) and the abutments were placed and secured with the appropriate abutment screws to the manufacturer’s recommend torque value, 25 Ncm (Figure 16). The definitive prosthesis was seated on the abutments and the occlusal retaining screws were torqued to 15 Ncm as recommended by the manufacturer (Figure 17A; Figure 17B; Figure 17C). The occlusion was checked, and adjusted as necessary. The author prefers to close the screw access holes with a cotton pellet and a provisional material. A panoramic radiograph was taken to establish a baseline reference point for future recalls (Figure 18). Both the prosthodontist and the surgeon were concerned about the soft tissue health and possible lack of attached gingiva after implant placement. A potential skin graft was discussed preoperatively with the patient and the decision was made to observe the patient’s hygiene after delivery of the prosthesis to determine if this additional procedure would be necessary. The condition of the tissues in the anterior mandible has remained very healthy and has posed no problem to date.
At a 6-month recall appointment, the abutment screw torque was checked and the access holes were definitively closed with cotton pellets and autopolymerizing acrylic resin or a light-polymerizing acrylic resin. A recall schedule was established to screen for possible neoplasm recurrence and evaluation of the prosthesis. The design of the prosthesis allows optimal performance of hygiene procedures by the patient as demonstrated by the use of a small interproximal dental brush (Sunstar Butler, Chicago, IL) (Figure 19).
A patient with an aggressive neoplasm was reconstructed through the multidisciplinary treatment planning and use of dental implants and a fixed prosthesis. Predictable function, esthetics, and stable periodontal health are achievable with newer techniques and materials such as titanium laser-welded frameworks. Laser welding allows the components to be attached on the master cast, eliminating some of the framework distortion problems caused with traditional investing and soldering. Dentists are treating more patients with complex problems using dental implants and it is imperative that practitioners provide their patients with predictable, long-lasting prostheses.16
The author thanks Dr. Kirk Fridrich for his surgical expertise in the implant placement and Dan Roberts from Midwest Dental Arts (Cedar Rapids, Iowa) for his assistance in the fabrication of the laser-welded titanium framework and definitive restoration.
The author is a current consultant for Thommen Medical.
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4. van Steenberghe D, Lekholm U, Bolender C, et al. Applicability of osseointegrated oral implants in the rehabilitation of partial edentulism: A prospective multicenter study on 558 fixtures. Int J Oral Maxillofac Implants. 1990;5(3): 272-281.
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8. Beumer J, Marunick MT, Curtis TA, et al. Acquired defects of the mandible: aetiology, treatment and rehabilitation. In: Maxillofacial Rehabilitation: Prosthodontic and Surgical Considerations. Los Angeles, Ca: Medico Dental International Inc; 1996:113-223.
9. Ortorp A, Jemt T, Bäck T, et al. Comparisons of precision of fit between cast and CNC-milled titanium implant frameworks for the edentulous mandible. Int J Prosthodont. 2003;16(2): 194-200.
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|Figure 1 Photograph of the intraoral condition before surgery to remove the lesion.||Figure 2 Panoramic radiograph of the lesion in the anterior mandible.|
|Figure 3 Panoramic radiograph of resected lesion before bone grafting.||Figure 4 Initial oral appearance of the patient after healing from the resection and bone graft.|
|Figure 5 The patient provided a clear thermoplastic splint that she had used after her previous orthodontic treatment, before the lesion was detected.||Figure 6 The splint was used to fabricate a tooth-color diagnostic wax-up, replicating the presurgical tooth position.|
|Figure 7 The tooth-color diagnostic wax-up can be tried in the mouth to evaluate esthetics and phonetics.||Figure 8A A restrictive surgical guide was fabricated from the diagnostic wax-up.|
|Figure 8B A restrictive surgical guide in use during preparation of the osteotomies.||Figure 9 Note the excellent soft tissue health after adequate healing with healing caps in place.|
|Figure 10 Implant level impression copings in place.||Figure 11 A master cast was created from the final implant level impression and poured in a low-expansion, high-strength dental stone.|
|Figure 12A The implant position in the master cast in relation to the clear guide fabricated from the diagnostic wax-up.||Figure 12B Incisal view of the implants and framework in relation to the guide.|
|Figure 12C Gingival position of the implants and framework in relation to the guide.||Figure 13A Apical view of the completed titanium laser-welded framework. Note the adequate connector dimension.|
|Figure 13B Incisal view of the framework with acrylic resin retention components added.||Figure 14A The SPI RETAIN abutments in place. Note the excellent tissue health.|
|Figure 14B The completed framework in place on the abutments with the retaining screws. Note the intimacy of fit of the copings to the abutments.||Figure 15A The completed prosthesis on the master cast facial view.|
|Figure 15B Incisal view. Note the placement of the implants.||Figure 15C Gingival view of the completed prosthesis with convex surface to facilitate hygiene procedures.|
|Figure 16 Delivery and tightening of the definitive abutments. Note the continued excellent soft tissue health.||Figure 17A Placement of definitive prosthesis, incisal view.|
|Figure 17B Facial view.||Figure 17C Patient smile with the definitive prosthesis in place.|
|Figure 18 Panoramic radiograph at delivery verifying fit, osseous levels, and baseline for future recall examinations.||Figure 19 Demonstration of oral hygiene procedures with a small interproximal dental brush. Optimal prosthesis contours allows good access and minimal food entrapment.|
|About the Author|
|Robert Schneider, DDS, MS |
University of Iowa Hospitals and Clinics
Hospital Dentistry Institute
Division of Prosthodontics
Iowa City, Iowa