Guided surgery as a way to simplify surgical implant treatment in complex cases

Transcription

1 52 STARGET 1 I 12 StraUMaNN CareS r ry vincenzo MiriSOLA Di TOrreSANTO AND LUCA COrDArO Guided surgery as a way to simplify surgical implant treatment in complex cases Background A 41-year-old woman with an edentulous maxilla and bilateral edentulous region (Kennedy Class I) in the mandible wanted removable restorations for both arches (Figs. 1, 2). Treatment plan The following plan was worked out to provide the patient with the simplest and most predictable surgical treatment possible. Due to prosthetic constraints (reduced inter-arch distance and short upper lip interfering with prosthetic flanges), a fixed implant-supported restoration was suggested even though the edentulous maxilla and posterior mandible exhibited atrophy (Fig. 3). Maxilla: conventional procedure Complex reconstruction with bilateral sinus lift and autogenous particulate bone harvested from the chin and multiple bone block grafts harvested from the ramus; four months after insertion of six implants and loading after an additional eight weeks with an FPD (Figs. 4 12). Fig. 1 Fig. 2 Fig. 3 FiGS 4-12: MAxiLLA, CONveNTiONAL PrOCeDUre Fig. 4 Fig. 5 Fig. 6

2 StraUMaNN CareS GUided SUrGery STARGET 1 I Mandible: guided surgery The mandible exhibited severe horizontal and vertical atrophy in the lateral-posterior region and remaining frontal dentition (from canine to canine), which, even if compromised, was considered maintainable after a periodontal non-surgical phase. After all, bone-harvesting sites in the chin and retro-molar region had already been used for maxillary surgery. A guided surgical procedure was planned and proposed in order to offer the patient the possibility for a less invasive surgical procedure. In addition, this would allow for the safe insertion of smaller implants, without requiring additional bone augmentation. Vincenzo Mirisola di Torresanto, DDS Degree in Dentistry and Dental Prosthetics. Clinical researcher at the Department of Periodontology and Prosthodontics at Eastman Dental Hospital in Rome, Italy. Awarded the H.M. Goldman Prize by the Italian Society of Periodontology for his clinical research in various national and international publications and lectures. ITI member and co-director of the ITI Study Club of Rome. Private practice in Rome. Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12

3 54 STARGET 1 I 12 StraUMaNN CareS r ry Fabrication of templates and computer-assisted planning The scan template was fabricated at the laboratory following the official guidelines of the Straumann Guided Surgery system: the initial template was fabricated with a suck-down technique and then filled with radiopaque material. Next, the templix reference plate was attached to the suck-down template on the Gonyx set with the D coordinate in the zero position before being completed for fitting in the patient s mouth. The DICOM data from the CT scan was processed with the codiagnostix software. The virtual planning strategy was to bypass the anatomical structures and make use of all available bone by using a safe and predictable procedure that remained simple and affordable for the patient. The proposed restoration was designed as a three-unit (44 46, 34 and 3.6), bilateral implant-supported FDP (Figs. 13, 14). The decision was made to insert two implants on each side in the first premolar and first molar positions. The 3D bone scan showed a reduced height and width in the molar sites and reduced width in the premolar sites (Fig. 15). All implants were planned so as to maintain a distance of at least 2 mm from the alveolar nerve. Insertion of a Straumann Tissue Level Implant RN ø 3.3 mm SLActive 10 mm was planned for both premolar sites. However, despite the selection of a reduced diameter implant, the virtual model of the inserted implant at 4.4 showed a marginal dehiscence (Fig. 16). For the distal implants, a Straumann Tissue Level Implant RN ø 4.1 mm SLActive 6 mm was planned for each side. Again, the virtual model of the implant inserted on the right side showed a minor marginal dehiscence (Fig. 17). FiGS 13-30: GUiDeD SUrGery 4 7

4 StraUMaNN CareS GUided SUrGery STARGET 1 I The planning for the axial inclination of the implant was anatomically-driven rather than prosthetically-driven. Using codiagnostix, it was determined that a 20 angulated abutment for the distal implants would make it possible to achieve the required parallelism with the mesial implants. Because of the dehiscences of the implants planned for 4.4 and 4.6, a traditional open flap procedure was chosen for the right side, while a flapless approach was taken for the left side. Two ø 2.8 mm sleeves were inserted in the right side of the surgical template; two ø 5.0 mm sleeves were inserted in the left side to prepare for the complete preparation of the site as well for the guided insertion of the implant (Fig. 18). Luca Cordaro, MD, DDS, Ph.D. Currently, Head of the Department of Periodontology and Prosthodontics at the Eastman Dental Hospital in Italy. Private practice in Rome, Italy. Active member of the Italian Society of Osseointegration. Fellow of the ITI and Chairman for the Italy chapter of the ITI, Chairman of the Study Club Committee and member of the Board of Directors. Author and co-author of scientific papers and literature, international lecturer. Dr. Cordaro s professional interests are periodontology, implantology and oral surgery, with a special focus on reconstructive treatments for alveolar atrophies. gonyx : Device for surgical template fabrication

5 56 STARGET 1 I 12 StraUMaNN CareS r ry Surgical procedure Bilateral local anesthesia was administered. The surgical template was placed and carefully checked to ensure stability before beginning the procedure. The mucotomy on the left side was performed by inserting a ø 4.3 mm round mucosa punch through the sleeves (Fig. 19). Implant sites 3.4 and 3.6 were prepared according to the drilling protocol suggested by the co-diagnostix software (long and short drill sequence, (Figs )), and the implants were inserted with the handpiece set with a force of 35 N and tightened manually after the template was removed. On the right side, a muco-periostal flap with horizontal incision at the top of the ridge and a distal vertical incision were made (Fig. 23). Both sites were drilled with a ø 2.8 mm drill (short for 4.6 and long for 4.4) through the ø 2.8 mm sleeve, with or without drill handle as required (Fig. 24). Implant site 4.6 was prepared with a ø 3.5 mm drill, drilling freehand to a depth of 6 mm. Both right-side implants were inserted with the handpiece set with a force of 35 N and tightened manually. Similar to the dehiscences seen in the virtual models of the implants, a vestibular dehiscence occurred in the case of both right side implants: a GBR procedure with a bone substitute and a resorbable collagen membrane was performed around each implant (Figs. 25, 26). The flap was opened, repositioned and sutured around the healing abutment. Prosthetic restoration The implants were observed two months after surgery and showed stability accompanied by no inflammation or pain. In addition, the radiographic evaluation showed successful 4

6 StraUMaNN CareS GUided SUrGery STARGET 1 I healing of the bone, without radiolucencies. A standard prosthetic protocol was followed. Two cemented fixed dental prostheses (FDPs) were planned: solid abutments for both mesial implants and 20 B angulated abutments were selected, again based on the virtual models (Fig. 27). Two porcelain-fused-to-metal triplicate FDPs were fabricated ( and ) and fixed in place with temporary cement (Figs. 28, 29). Conclusion In this case, the virtual planning models and the actual outcome (Fig. 30) demonstrated that the Straumann Guided Surgery System ensures a high level of precision for the purposes of implant positioning. To achieve the most accurate results, a guided implant insertion is recommended. This case was treated with Straumann Soft Tissue Level Implants, according to the routine protocol for lateral-posterior rehabilitations. As a further consideration: in the author s opinion selecting Straumann Bone Level Implants is the best way to maximize the benefits of the system, potentiality making it easier for the clinician when it comes to soft tissue management (especially for flapless procedures) and providing a wider range of options for prosthetics. Combined with the ability to perform a predictable and safe flapless procedure, one interesting indication for the Straumann Guided Surgery system is potentially the bypassing of anatomical structures which in carefully selected cases and in the hands of experienced clinicians can reduce or eliminate the need for bone augmentation and the associated treatment complications. 7