2021, Number 3
Benefits and complications of implant guided surgery in a total edentulous patient, case report
Language: English/Spanish [Versión en español]
References: 10
Page: 239-246
PDF size: 341.18 Kb.
ABSTRACT
Computer-aided guided implant surgery (CAGIS) has considerably progressed in recent years, generating an explosive use. Different systems have been developed to plan and perform surgeries on partially and totally edentulous patients. Many studies have reported the benefits and complications associated with this procedure. Benefits associated with a better postoperative period for the patient are reported and reduced surgical time. However, several authors describe complications such as the settlement of the guide and the implant position, among others. Therefore, a safety margin of at least 2 mm is recommended for the planned implant placement.INTRODUCTION
Implant-assisted prosthetic rehabilitation of the edentulous patient is highly predictable and successful. Furthermore, due to the advancement and development of new technologies such as 3-dimensional (3D) imaging, computer-aided design (CAD), computer-aided manufacturing (CAM), and intraoral scanning, the CAGIS has become a reality.1-4
The CAGIS allows positioning the planned dental implants (DI) prosthetically guided by a computer program to the desired surgical site.2,4,5 The development of this therapeutic alternative has advantages for the patient and the clinician and disadvantages and complications derived from the planning and correct execution of a CAGIS.1,5-8
A case report developed in the Postgraduate Course in Prosthetic Surgical Implantology (Facultad de Odontologia de la Universidad San Sebastian, Campus Santiago) is presented, where the advantages and disadvantages of the CAGIS in totally edentulous patients are evident.
CASE REPORT
A 65 years old Chilean female patient was referred from a private consultation to the postgraduate course in Prosthetic Surgical Implantology (Universidad de San Sebastian, Santiago de Chile) for multidisciplinary rehabilitation treatment.
The patient reported suffering from arterial hypertension controlled with losartan 50 mg tablets (1 daily dose) at the anamnesis. The clinical examination showed a removable partial prosthesis, upper acrylic, maladapted, retention, and stability problems (Figure 1); lower partial edentulism; caries and periodontitis III, B. Therefore, an implant-assisted upper hybrid type prosthesis with a CAGIS was planned. The diagnostic phase consisted of evaluating and obtaining the patient's clinical data through intraoral and extraoral photographs, taking study models, and assembling in an articulator to manufacture the upper removable total prosthesis and the lower removable partial prosthesis. These latter were performed to obtain a correct 3D positioning of the mandible using aesthetic and phonetic parameters and occlusal stabilization for the subsequent planning of the DIs. Three alignment tests were performed with dental selection using the patient's biotypology to do this. The Marché brand color chart was used (Figure 1).
Once the prosthesis was placed, a prosthetic duplicate was generated with barium sulfate for a CT scan to program the CAGIS. The prosthetic copy was applied tray adhesive (3M®), and an impression was made with polyvinylsiloxane (3M®) in medium consistency. The closed bite impression was taken, imitating the myofunctional impression technique. Immediately, once the impression material was polymerized, the tomographic examination was done, the impression was removed from the mouth, and pouring with stone plaster was carried out. It is worth mentioning the importance of generating a good base when pouring (Figure 2A).
The pouring made on the replication of the prosthesis with the silicone impression was analyzed in a tabletop scanner (Straumann® Serie 7) to obtain an STL (Standard Triangulate Language) model. Finally, the impression of the duplicate of the plaster model was removed to get a new STL of the edentulous model of the patient (Figure 2A). This procedure is known as trifusion,5 where it is sought to employ computational software, to join the data of the tomography, the STL with the replication, and the STL without it. The references of hard tissues, prosthetics, and soft tissues, respectively, can be obtained with these data. The trifusion was performed in the planning software (CoDiagnostix Straumann®).
The DICOM (Digital Imaging and Communication on Medicine) file and the STL were joined with prostheses, to later join the STL without prosthesis with the two previous ones. To achieve a correct joint is essential that in the base generated with the plaster, perforations are made that allow joining both files using these references. The composite resin points are seen in the duplicate also facilitated joining the DICOM file and this STL (Figure 2B).
With the trifusion of the files, surgical planning was done to determine the three-dimensional position of the DIs using the prosthetic reference already available in the digital planning and biological references of the DICOM file. The installation of 6 DI (Neodent® Grand Morse Acqua), Drive-in position of 1.6 (3.5 × 10 mm), 1.4 (3.5 × 8 mm), 1.2 (3.5 × 10 mm), 2.2 (3.5 × 10 mm), 2.4 (3.5 × 8 mm), 2.6 (3.5 × 10 mm), was planned (Figure 2B). Once each of the DIs positions was determined, the surgical guide (SG) was designed with anchoring through fixing pins (Neodent®). In addition, the guide was impressed with a biocompatible resin (Shera SG) using a 3D printer (Sprintray® S100) (Figure 2B).
The patient was scheduled for an adjustment and settlement test with the SG design, confirming its correct position and adaptation. Then, the SG was installed using the fixing pins in the surgery, anesthetizing their entry with infiltration technique. The guide was positioned, the entrance of each ring where the DIs were installed was anesthetized, with the identical method. The soft tissue was removed with a Tissue Punch incorporated in the Neodent® Guided Surgery Kit. Then the drilling protocol was performed for each "DI", using the relevant reducers contained in the surgery kit (Figure 3A).
Once the DIs were installed, the SG was removed to perform a full-thickness flap due to the need to increase horizontal bone tissue given the biological conditions of the surgical site. When performing the mucoperiosteal flap, the position of a DI can be observed practically in soft tissue (Figure 3B). The bone augmentation was performed with a bone allograft (Maxgraft, Botiss) and a resorbable collagen membrane (Jason, Botiss). Due to the large bone regeneration surgery, the DIs were left submerged with closure caps, and 4 mini-implants (Mini Plus Cowell Medi) were installed to stabilize the patient's total prosthesis (Figure 3C).
After 10 months, the neoformation of bone tissue and the DIs osseointegration remained stable, so the surgery was performed to connect them (Figure 4A). After 3 weeks the installation of straight and angled conical mini abutments (Neodent GM) was carried out according to prosthetic needs for the proper healing of the soft tissues. Subsequently, the impressions were taken with the multifunctional tray technique, taking advantage of the exact barium sulfate duplicate. Acetate impressions were made to mark the implants' exit and facilitate the multifunctional tray drilling. Temporary titanium cylinders (Neodent® GM) were installed, and the corresponding impression was taken. The bar was designed and drilled in a digital laboratory (Cerolab, Chile) (Figure 4A). The bar was tested and adjusted, and definitive rehabilitation with definitive torque was installed (Figure 4B).
DISCUSSION
Several authors mention the GIS advantages,1,5,6,8 including the correct three-dimensional position of the implants, decreased surgical time, and better postoperative period for the patient. However, the disadvantages and complications associated with this procedure have also been well documented.1,6 For example, the wrong 3D position of implants when procedural errors accumulate (which is even more significant when mucosa-supported and non-tooth-supported guides are made), technical sensitivity, costs, planning time, and difficulty in fixing the guide, among others.
Moraschini et al. mention in their systematic literature review the surgical, postoperative, and prosthetic complications associated with GIS at complete arches. The most prevalent surgical complications are the difficulty of installing the SG with good adaptation at the time of surgery and DI fenestrations in the surgical act.9 Laleman et al. describe complications as early and failures in GIS, measured from surgery and up to 2 weeks after.1 The most frequent complications were fracture of the SG, difficulty stabilizing the SG, and difficulty achieving adequate primary stability. However, reasonable DI survival rates are reported in totally edentulous patients using GIS, coupled with a high acceptance by patients in terms of postoperative pain and swelling.1
D'Haese et al. conclude that the survival rate of DI using GIS ranges from 91 to 100%. As for the precision of guided surgery, they propose to maintain 2 millimeters of safety margin in all directions (vestibular-lingual or palatal, mesial-distal, apical-coronal).5 For their part, Schneider et al. report an incidence of 9.1% of complications associated with the use of GIS. The most frequent are fracture of the SG, difficulty in settlement of the SG, and early loss of DI due to the lack of primary stability.7
Moon et al. demonstrated the difference of planned and installed implants using GIS, although this did not mean patients' treatment complications.10
CONCLUSIONS
The CAGIS is a viable therapeutic alternative for DI installation that produces some benefits related to tolerance and patient experience. In addition, it is a minimally invasive procedure (however, guided surgery is not synonymous with flapless surgery). Some complications associated with this procedure are the positional alteration of the planned DIs versus the installed DIs, SG fractures, and difficulty in obtaining primary stability. Therefore, it is suggested to maintain a safety margin of 2 mm in the different spatial dimensions of the surgical field. Finally, the SG must be tested before the procedure to ensure its correct settlement. The technique accuracy depends on the accumulation of errors generated from obtaining files to the execution in the same surgery.
The trifusion as a digital planning method reduces the error rate in the CAGIS, especially concerning the settlement of the SG. However, scientific studies should continue to improve the accuracy and decrease other complications.
AGRADECIMIENTOS/
Dr. César Coronado: metodología; Mauro Risso: soporte técnico CAD CAM; Dr. Filippo Moenne: fotografía.
REFERENCES
AFFILIATIONS
1 Postítulo implantología quirúrgico-protésico, Facultad de Odontología, Universidad San Sebastián sede Santiago.
CORRESPONDENCE
David Torres-Ibieta. E-mail: drtorresibieta@gmail.comReceived: Agosto 2020. Accepted: Septiembre 2021