Case report
A female patient in a good general health consulted the prosthetic department for a prosthetic rehabilitation with esthetic and functional request.
The oral examination revealed cracks at the anterior incisors the 11 and the 21, an inversion of the Spee’s curve and an abrasion on the mandibular teeth. There were mandibular bridges from the 12 to the 16 and from the 33 to the 37. There were also maxillary bridge from the 24 to the 26. These fixed prostheses had a bad dento-prosthetic joint (Figure 1 A,B,C).
The vertical dimension of occlusion was maintained.
The radiological examination showed that the 37 presented a bone lysis reaching the apical third. An infrabony perforation was noted at the level of the 33. The 15 was dilapidated. The other remaining teeth had a radiological crown -radiological root ratio less than 1 except the 24 which presented an infra-osseous decay (Figure 1D).
Oral cavity sanitation treatments have been carried out including hygiene motivation, removal of defective bridges, extraction of the 24, 37 and 33 and caries curettage on the 16. The 15 was reconstructed using a false stump coping.
After the oral cavity sanitation phase, the patient was categorized clinically as a Kennedy class III in the maxillary arch. In the mandibular arch, the situation was more delicate in the presence of a distal extension edentulism bordered anteriorly by the lateral incisor.
Based on the clinical data and the diagnosis elements, ceramo metallic full arch was indicated in the maxilla.
In the mandibular arch, three treatment options were discussed with the patient: implant supported fixed prosthesis (ISFP), ISRPD or conventional RPD.
The patient was aware of the cost of an ISFP. Nevertheless, she wants a stable and functional prosthesis. The decision was to realize an ISRPD combined with fixed restorations on the anterior teeth. Locator attachment will be used as a complementary retention device.
Study casts prepared from preliminary impressions were mounted on the articulator at adequate occlusal vertical dimension. The prosthetic usable occlusal height was equal to 6 millimeters (mm). The diagnostic waxes and the director mounting realized constituted an indispensable communication tool in the patient-practitioner-prosthetist triad (Figure 2). The conception of the prospective metal framework supported by strategic implant has been elaborated (Figure 3).
Prosthetic steps were started with peripheral preparations of the 11, 21, 22, 23, 31, 32, 41, 42, 43 and the rectification of the preparations on the 12, 15, 16 and 26 (figure 4 A,B) followed by the realization of the first generation temporary fixed prostheses. The director mounting was polymerized and served as mandibular provisional acrylic resin RPD. This one was duplicated in order to be used as radiographic and surgical guide.
The global impressions had been taken (figure 4 C,D), followed by the occlusion recording. the fixed restorations were realized according to the prospective layout of the metal framework (figure 4E). The particularity of the mandibular crowns was the millings (figure 4 F) that will receive the metal framework components.
Computed tomography assessment revealed bone deficiency in height in the left mandibular posterior region (Figure 5). An implant will be placed in the site of the left first molar to transform the terminal tooth loss into an intercalary edentulism. The length and the diameter of this implant were respectively 8.5 mm and 4.2 mm.
Implant placement has been performed (Figure 6A to F). Following osseointegration of the implant, healing abutment was placed and was left for 2 weeks to allow the healing of peri-implant soft tissues (Figure 6G).
The realization of ISRPD was started by making the primary anatomical impression using a commercial impression tray and a silicone according to the simultaneous double mixing technique. The healing screw was in place to visualize the future notch in the metal framework which coincided with the location of the implant. The objective of this impression was to record the dental and osteo-mucous support surfaces (Figure 7A).
The metal framework was realized in the laboratory respecting the framework layout already established (Figure 7B). The try-in of the framework was carried out in the mouth.
This framework served as a support for a sectorial anatomo-functional and situational impression. The first step consisted on the equipment of the saddle with formatray resin.
The resin has been removed in front of the implant (Figure 7C). Subsequently, the peripheral joint was modeled at the level of the edges of the terminal saddle. Then, healing abutment was unscrewed and impression coping was placed into the implant (Figure 7D). Anatomo functional and situational impression was taken using polyether (Figure 7E). This rigid material allowed the implant position transfer. After the material has set, the impression coping was unscrewed and the frame was un-inserted.
Implant laboratory analogue was attached to the impression coping and the casting of the impression has been carried out. Thus, the corrected cast was obtained (Figure 7 F,G,H).
After bite recording, the teeth arrangement on wax was carried out and evaluated intra-orally (Figure 7I). Heat-curing acrylic resin was processed in the laboratory. In this step, locator abutment was connected to the implant laboratory analogue and the black laboratory sheath was used.
Locator abutment was tightened on the implant. The metal box was placed on the female part of Locator abutment and the spacing was checked at the level of the intrados of the prosthesis using a low viscosity silicon (Figure 8A,B,C).
A piece of rubber dam was putted in place to prevent the resin from melting during the chemical polymerization (Figure 8D). The chemical-curing resin was prepared (Figure 8E) and the prosthesis was inserted in the mouth. The polymerization takes place under occlusal pressure.
After disinsertion of the prosthesis, the metal box was transferred to the intrados (Figure 8F). The black sheath will be replaced by a plastic retentive part (Figure 8G).
The patient was very satisfied with the final result (Figure 8 H,I). Oral hygiene instructions were provided, particularly for the maintenance of peri-implant tissues, gingival and mucosal surfaces of the prosthesis.