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ePaper created 2017-12-06, 12:03:50 | version 1.38.0
in loss of the teeth involved.8 In periodontitis, the normal balance between bacterial plaque and the immune defence is altered and this leads to imperfect regulation of the inflammatory response, resulting in increased marginal periodontal destruction.9–11 When bone loss is consistent and makes it difficult or even impossible to place straight implants, it is possible to opt for tilted implants. The use of tilted im- plants allows the reduction of the distal cantilever and a better distribution of the forces.12 In addition, the angle allows the use of longer implants, insertion of the implant into a better bone structure, and the pres- ervation of noble anatomical structures, such as the mandible and the maxillary sinus.13, 14 When a masticatory load is applied to a cantilever, compression forces are exerted on the distal implants and traction forces on the anterior implants. The magnitude of these forces is directly proportional to the length of the cantilever.15 It has been shown that, with the insertion of four or six implants of the same length as the cantilever, forces acting on the most distal and anterior implants are comparable, allowing the simplification of the surgical procedures.15–17 The implant angle also reduces the compression load in the connective area between abutment and bar and does not induce bone crest abnormalities compared with straight implants.15, 18 In this article, the clinical situation of two male patients aged 66 and 67, respectively, are described, both of whom complained of mobility of residual teeth, periodontal problems, caries and poor aesthet- ics. The purpose of this article is to describe a new prosthetic protocol called Double FiRe (Fixed/Remov- able) Bridge, highlighting its functional, aesthetic and hygiene advantages. This protocol provides fixed rehabilitation of edentulous arches by the insertion of four tilted implants. Case 1 The patient showed signs of generalised chronic periodontitis that involved most teeth in both the upper and lower arches (Figs. 1a & b). Since the max- illary sinus was greatly pneumatised, there was in- creased difficulty of implant placement and proper prosthetic design. The extraoral examination found a convex, divergent profile with good masticatory muscle trophism. The perioral tissue was maintained and the nasolabial angle was around 90°. After care- ful diagnosis and clinical data collection, a treatment plan was developed that would involve a fixed max- illary implant prosthesis and a mandibular overden- ture attached to the canine roots (#33 and #43), and two implants inserted into the interforaminal area (#32 and #42). Fig. 2 Surgical protocol The surgical protocol entailed anaesthesia at the level of the entire upper arch with articaine with 1:100,000 adrenaline, and antibacterial prophylaxis was administered in the form of 875 mg of amoxicillin plus 125 mg of clavulanic acid provided one hour be- fore surgery and continued every 12 hours for six days. The teeth were extracted as carefully as possible not to damage the postextraction sites. Subsequently, a full-thickness flap was performed to achieve better vi- sual access to the surgical area. Four exterior hexago- nal implants (4 × 13 mm; Co-Axis 12 and 24°, Southern Implants) were placed in regions #15, 12, 21 and 24 (Fig. 2). Distal implants were angled to minimise the distal cantilever and to improve transmission of the masticatory load. The maxillary implants were placed at a torque reaching over 40 Ncm in order to follow an immediate loading protocol. At the end of the surgical procedure, suturing was performed using 4/0 silk. Prosthetic protocol At the end of the operation, a polyether polyure- thane impression (Impregum Penta, 3M ESPE) was taken, after bounding the impression copings with dual composite for greater precision. After 24 hours, the patient was provided with a fixed maxillary provi- sional prosthesis in acrylic resin with a cobalt–chro- mium internal reinforcement to have greater rigidity of the structure and better distribution of the load between the implants. The provisional was screwed directly to the fixture without the interposition of a multi-unit abutment owing to the geometry of the implants used. They have an angled prosthetic con- nection from the longitudinal axis, and this provides the possibility of correcting divergences. A lateral cephalometric radiograph confirmed the exact posi- tion of the prosthetic incisors from the alveolar crest, highlighting that the fixed rehabilitation was the best choice in this case (Fig. 3). Owing to the marked angulation of the distal im- plants, it was possible to reduce the cantilever and industry | Fig. 2: Post-op dental panoramic tomogram showing the positioning of the maxillary implants. implants 4 2017 21