Indication 4 Case 4

Single tooth gap maxilla


Dr. Urs C. BELSER, Professor and Chairman
Department of Prosthodontics
Dr. Jean-Pierre BERNARD, Médecin adjoint
Department of Stomatology and Oral Surgery, School of Dental Medicine, University of Geneva, Switzerland

Laboratory work:
Mr. Michel BERTOSSA, CDT
School of Dental Medicine, University of Geneva, Switzerland

Introduction
The case of a 19-year old female patient, congenitally missing all four permanent maxillary premolars, is presented to discuss the importance of a pluridisciplinary approach including pre-implant orthodontic therapy on the one hand, and the prosthetic options in association with a reduced interarch distance on the other hand.

	Fig. 1: Frontal view of a 19-year old female patient, congenitally missing all four permanent maxillary premolars, as well as the two second mandibular premolars.

	Fig. 2: Occlusal view displaying bilaterally edentulous spaces in the premolar area. Despite a previously performed orthodontic therapy, aiming at reducing the edentulous spaces to the size of one premolar, the mesio-distal gap width in the area of tooth number 14 is insufficient for the insertion of an implant.

	The intrasurgical status shows both implant recipient sites following preparation of the implant beds.

	Fig. 4: A similar situation regarding interarch distance is present on the patient's left side.

	Fig. 5 & 6: The corresponding radiographs underline the need for additional orthodontic therapy prior to the insertion of implants, especially on the patient's right side.

	Fig. 7: After six months of orthodontic treatment using an upper fixed full-arch appliance, the dimensions of the two prospective implant sites appear compatible with this kind of therapy.

	Fig. 8 & 9: The respective x-rays confirm bilaterally adequate space for the placement of single-tooth implants.

	Fig. 10 & 11: Three months after implant surgery the peri-implant soft tissues are almost completely healed. Note the distinctly submucosal location of the implant shoulder which had been chosen to comply with esthetic parameters on the one hand, and to overcome problems associated with limited interocclusal distance on the other hand.

	Fig. 12: The occlusal view of the implant at the location of tooth number 14 immediately after removal of the titanium healing cap confirms favorable soft tissue conditions. Furthermore, the internal octagon which can be used for both as an indexing feature or as an antirotational lock, becomes clearly visible.

	Fig. 13: In order to transfer the in-mouth situation at the implant level to the dental laboratory, an injection-moulded self-centering plastic impression coping is attached to the implant shoulder, supplemented by a central positioning cylinder for the pick-up of the spatial orientation of the internal octagon. Note that this simple approach is compatible with the use of a stock tray.

	Fig. 14: Once the impression performed, the implant is covered again with a titanium cap. The choice of it's height depends on the location of the implant shoulder in relation to the soft tissue margin, the objective being the maintenance of a soft tissue channel from the implant shoulder to the mucosal surface.

	Fig. 15: Close-up view of the previously described auxiliary parts embedded in polyether impression material. Note the octagonal feature of the positioning cylinder.

	Fig. 16: After attaching the aluminium laboratory analogue, the impression is ready for pouring with either type IV stone or epoxy resin.

	Fig. 17: Occlusal view of the completed maxillary working cast. The peri-implant soft tissue configuration has been reproduced in silicone and can be easily removed when required during the suprastructure fabrication process.

	Fig. 18: In this specific case, primarily due to the reduced interarch distance, a screw-retained suprastructure in general, and a transverse screw path in particular has been adopted. The occlusal view displays the situation after insertion of the respective abutments.

	Fig. 19: A prefabricated precious alloy coping will serve as base for the fabrication of the planned ceramo-metal suprastructure.

	Fig. 20: Occlusal view of the upper arch after incorporation of the two implant supported single-tooth restorations. Note that until this stage the orthodontic appliance has been left in place.

	Fig. 21: The right lateral close-up view confirms an adequate esthetic integration of the suprastructure. Due to the distinctly submucosal location of the implant shoulder no cervical metal margin is visible.

	Fig. 22: Only after having verified the presence of appropriate interproximal and occlusal contacts, the orthodontic space-maintainer is removed.

	Fig. 23: Final frontal view. Note that the two implant restorations blend discreetely into the patient's natural dentition from both a form and colour point of view.

	Fig. 24 & 25: The oblique occlusal views of the two suprastructures clearly demonstrate the advantage of the transverse screw retention design: no occlusal screw access channels interfere neither with functional occlusal morphology and esthetics nor with structural requirements inherent to the porcelain-fused-to-metal technology.

	Fig. 26 & 27: Radiographic controls taken one year after the insertion of the two 10mm solid screw implants, showing adequate marginal fidelity and stable, favorable conditions concerning the bone to implant interface.