Reconstruction of Edentulous Maxillary and Mandibular Arches With Implant-Supported Fixed Restorations Using a Digital Treatment Planning Technique: A Clinical Report

In recent years, the art and science of dental implants and prosthodontic therapy have made impressive progress in the replacement of the missing dentition.1 Oral rehabilitation using implants is a well-established and a widely used procedure worldwide.2 Rehabilitation of oral function can be accomplished successfully with the placement of endosseous implants to support dental prosthesis with improved stability and retention. These endosseous implants are biologically compatible and a predictable treatment modality for both partial and complete edentulism.3 Edentulous maxillary and mandibular arches can be restored with several prosthetic designs, such as conventional complete dentures, implant-supported complete or partial fixed dentures, or implant-retained removable overdentures supported by implants, tissue, or a combination of both. Most patients prefer fixed restorations and ask for their removable prosthesis to be eliminated.4 Implants are used as osseointegrated supports for fixed or removable dentures to restore the function, esthetics, comfort, and speech of edentulous patients.5 This article reports on the successful treatment of a completely edentulous patient with fixed partial dentures supported by 16 implants.

A 61-year-old man applied to Yeditepe University School of Dentistry, Department of Prothodontics, Istanbul, Turkey, for treatment of maxillary and mandibular edentulism (Figure 1). The patient's chief complaint was the poor appearance and reduced function of his existing complete maxillary and mandibular dentures. Review of the patient's medical history revealed that he was taking oral antidiabetic medication (Glukofen, Sandoz Novartis, Holzkirchen, Germany) and a medication to reduce cholesterol. On clinical examination, it was noted that neither jaw showed any signs of severe atrophy. Radiological examination was performed with panoramic radiography (Trophy Orthoslice 1000 C, Trophy Spa, Lissome, Italy) and demonstrated that there was adequate bone volume for implant placement in both jaws. According to clinical and radiological assessment, 3 treatment options were discussed with the patient: conventional complete dentures, implant-supported overdentures, and implant-supported fixed partial dentures. The patient rejected the use of a removable denture and consented to have implant-supported fixed partial dentures.

Impressions of the maxillary and mandibular arches were made with an irreversible hydrocolloid material (Kromopan, Lascod, Italy) and poured in dental stone. Baseplates and occlusal rims were fabricated on the stone casts. After face-bow (Rotofix, Girrbach, Germany) transfer, centric relation record, and occlusal vertical dimension determination were performed, the stone casts were mounted in a semiadjustable articulator (Artex TK, Girrbach, Germany) (Figure 2a and b). According to occlusal rim measurements, denture teeth with 66% to 67% radiopaque barium sulphate material were selected (Vivo TAC/Ortho TAC, Ivoclar, Vivadent) (Figure 3). After the arrangement of the denture teeth, a wax esthetic try in was performed to verify the accuracy of the maxillomandibular relationship and to obtain patient approval of esthetics (Figure 4). In the laboratory, the wax setup was then invested in a flask, finished, and polished.

The patient wore the prosthesis while being scanned. Review of the reformatted computerized tomography (CT) scan defined the position of the new fixed partial dentures with respect to the available bone, and the initial placement of the implants was established using dental-planning software (SimPlant, Materialise, Belgium). Implant positions were altered on the cross section to balance the needed restorative position and the available bone contours (Figure 5a and b). The treatment plan was completed and mailed to the software manufacturer, which generated resin models of the mandible and maxilla and surgical templates (SurgiGuide, Materialise, Belgium) with stainless steel guide tubes (Figure 6).

Local infiltrative anesthesia with mepivacaine hydrochloride (Isocaine 3%, Novocol, Canada) was applied before implant placement. The surgical procedure was initiated with an intraoral crestal incision. A full-thickness mucoperiosteal flap was elevated both buccally and lingually to expose the bone. All remaining soft tissues that would make contact with the surgical guide were removed from the bone surface. After flap elevation, each surgical guide was tried in to verify that it was stable and seated firmly without the need to exert excessive pressure on the guide (Figure 7a and b).

Based on the drilling sequence, surgical guides were designed as a series with steel cylinders in graduated diameters to accommodate the specified diameters of each drill (Figure 8). The guide was held down in the middle or on each of the 2 ends to prevent it from tilting or shifting. The guide's position was maintained on the bone during the drilling process. Once drilling for all the implants was finished, the position and direction of the implant sites were clinically assessed before proceeding with the next guide. Eight screw-type implants with titanium oxide–blasted surfaces (Astra-Tech, Mölndal, Sweden) were placed in the maxilla (Table 1). After the implants were placed (Figure 9), the mucoperiosteal flaps were repositioned and sutured in place. One month later, 8 screw-type implants were surgically placed in the mandible using the same procedure as maxilla (Table 1). A panoramic radiograph was taken to examine the implant positions in both jaws (Figure 10).

Postoperatively, the patient was prescribed amoxicillin 675 mg, 3 times per day for 7 days, and naproxen sodium 550 mg, 2 times per day, as needed for pain. In addition, the patient was instructed to rinse with 0.15% benzydamine HCl and 0.12% chlorhexidine gluconate solution 2 times a day for 1 week. At clinical follow-up of 7 days later, a clinically healthy mucosa was observed. The patient did not complain of postoperative pain or swelling and was able to refrain from wearing his prosthesis for 2 weeks after each operation. Two weeks after the surgery, the patient's complete denture was relined with a soft material (Viscogel, Dentsply, York, Pa). This soft material was changed monthly during the healing period. After a healing period of 5 to 6 months (5 months for mandible, 6 months for maxilla), the implants were exposed and healing abutments were connected. Two weeks later, the patient was ready for definitive fixed restorations.

Healing abutments were removed, and transfer copings were connected to the implants for an implant-level impression (Figure 11a and b). A custom tray was used to make the final impression with silicone-based impression materials (Zetaplus and Oranwash L, Zhermack, Italy). Transfer copings were removed, connected to implant analogs, and placed into the corresponding holes in the final impression 1 at a time (Figure 12a and b). Master casts were fabricated and trimmed, and record bases and occlusion rims were made. The patient returned for face-bow transfer and recording of maxillomandibular relations (Figure 13). Master casts were then mounted on a semiadjustable articulator (Artex TK, Girrbach, Germany). Preparable abutments were connected to the implant analogs. The abutments were prepared on a surveyor to develop the path of insertion and to create adequate retention and resistance (Figure 14).

Six cement-retained, porcelain-fused-to-metal (PFM), fixed partial dentures were fabricated (Table 2). Frameworks were waxed, cast in a semiprecious alloy, and returned from the laboratory for a trial fitting. The stability, marginal fit, and occlusion of the framework were verified (Figure 15). A porcelain shade was selected and approved by the patient, and the frameworks were returned to the laboratory for application of porcelain. A clinical remount was performed to allow final verification of fit, esthetics, and refinement of occlusal contacts. A canine-protected articulation was established in this phase. The porcelain was glazed, and the fixed prosthesis was cemented onto the abutments with a cement for implants (Premier Implant Cement, Plymouth Meeting) (Figure 16a and b). Oral hygiene instructions and techniques were reviewed, particularly in relation to the home care of the PFM restorations. The patient was scheduled for follow up and oral prophylaxis.

Restorative dental treatment of edentulous patients should be based on through understanding of the chief complaint. The dentist must listen carefully to the patient's expectations, combine this information with the clinical examinations, and formulate a treatment plan.6 Most edentulous patients prefer a fixed restoration instead of a removable denture.7 According to data obtained from extraoral, intraoral, and radiologic examinations and patient history, if bone and soft tissue deficiencies cannot be compensated by a fixed restoration, a removable reconstruction is the most desirable alternative solution.

Facial parameters, such as facial support, lip support, smile line, and upper lip length, should be clinically examined. If soft tissue support is needed, this can be achieved mainly by the buccal flange of a removable restoration. Any need for extraoral soft tissue support should be evaluated with the patient facing forward and in profile.8 In the maxilla, an evaluation of the smile line should be performed without the denture in place. If the alveolar ridge is displayed during smiling, the use of a buccal flange in a removable prosthesis may be advisable to prevent esthetic problems.9 Because the upper lip length affects the position of the maxillary anterior teeth, it should be assessed during the examination. In patients with a short upper lip, the maxillary anterior dentition will normally be exposed. In patients with a long upper lip, the incisors will usually be covered.8 In the present case, facial parameters, such as soft tissue support, smile line, and upper lip length, were assessed, and the patient was deemed as a candidate for fixed restorations.

Intraorally, vertical dimension, quality and quantity of the mucosa, and quantity and contour of the underlying bone should be evaluated. The principles and rules of complete denture prosthesis rehabilitation can be applied while detecting the vertical dimension. Sufficient mucosal thickness helps to hide the abutment margin and facilitates correct emergence profile of the clinical crown. In a situation with advanced underlying bone resorption, making a fixed restoration would cause long and buccally flared teeth with large interproximal spaces or visible abutments entering the mucosa. Because facial support cannot be accomplished adequately, speech may be disturbed and esthetics compromised.8 In the present case, the interarch space was assessed by preparing the diagnostic setup. Based on intraoral examination, it was decided that the patient could have fixed restorations.

For precise estimation of the available bone, which affects implant position, angulation, and length, a CT scan with a radiographic template is highly recommended.10 The case-planning software in this report used high-quality CT images for the preoperative planning of dental implants to satisfy the patient's needs for esthetics, phonetic function, and acceptable occlusal function. A scan prosthesis that localized the proposed teeth in some fashion was fabricated. The patient wore this prosthesis while being scanned.11^,12 The CT scan defined the position of the new prosthesis with respect to the available bone. Implant positions were altered according to the needed restorative position and the available bone contours. This detailed presurgical planning minimized potential difficulties during the prosthetic procedure.

Implant-supported restorations can be attached directly to implants with screws, or they can be cemented to abutments. There are several advantages and disadvantages of these methods. Screw-retained restorations are more easily retrieved but can be used only when the trajectory of the implant allows the screw access to be in nonesthetic areas. They are more effective than cement, especially in areas of limited interarch space, because of the lack of abutment height. Cement retention can be used more universally and can accommodate more implant positions. The cement space also provides a stable, passive environment for the framework. The lack of screw holes in cemented restorations provides a design that enhances the physical strength of porcelain and may result in less fracture. Cement-retained implant prostheses provide easier access to the posterior jaw, reduced laboratory costs, reduced complexity of components and laboratory procedures, and reduced chairside time. In addition, cement-retained prostheses have superior esthetics, which is important from the patient's perspective.13^,14 When these advantages were taken into account, cement-retained prostheses were deemed most appropriate for the present patient. Prosthesis fabrication was similar to that of a conventional fixed prosthesis. On the left side of the maxilla and mandible, the prosthesis could be divided because the implant placement allowed fabrication of 3-unit bridges. However, on the right side, implant placement only allowed for fabrication of 6-unit bridges.

The long-term success of mandibular fixed implant-supported prosthesis has been well documented. A prospective study evaluating implant treatment in the edentulous mandible presented excellent results over more than 20 years for the fixed implant-supported mandibular prosthesis.15 Studies comparing implant-retained overdentures with fixed implant-supported prosthesis have found little or no significant difference when testing for objective function measure and subjective patient satisfaction.16^,17 

Comparatively, rehabilitation of the edentulous maxilla with a fixed implant-supported prosthesis continues to be more challenging than rehabilitation of the edentulous mandible because of the potential presence of pneumatized sinuses.18 However, recent advances in diagnostic imaging modalities, bone-grafting protocols, and prognostic technology have made the implant option for the edentulous maxilla increasingly the treatment of choice for many patients.19 

The lack of internal loading of the alveolus after removal of the dentition leads to its atrophy. By placing implants, internal loading of the edentulous alveolus is restored and preservation of the remaining bone is possible. This is the basis for the success and popularity of implants. Dental implants not only stabilize a patient's prosthesis but, more important, also biologically and physiologically help to maintain the remaining alveolar bone. In a maxilla with severe resorption, implant size, angulation, and localization are the major challenges. This clinical report describes the prosthodontic management of a 61-year-old edentulous patient with implant-retained fixed partial dentures by using a software-planning technique. Satisfactory esthetic and function were provided in the present situation.