Implantoprosthetic Rehabilitation by Computer-guided Implant Surgery (M-Guide): Case report.

Correct implant positioning poses a major challenge in modern dentistry and mismatch between the planned and final implant position is one of the most common treatment complications. A surgical guide or a template is a ''transmission device'' which enables the implant placement in the intended position as accurate as possible. Case study: A woman aged 60 came into dental office to resolve a single tooth loss in regions 15 and 24. Radiographic analysis and clinical examination showed a lack of transversal space in the regions of implantation. Considering the fact of having a narrow area available for implantation, a computer-guided implant therapy using the M-Guide system was selected. The treatment plan was a prosthetic restoration involving the placement of two implants in areas 15 and 24 and the fabrication of zirconium oxide crowns. After digital planning, a fully guided surgical protocol was performed. Immediately after implantation, a temporary suprastructure and temporary crowns were placed. After a period of osseointegration, a definitive prosthetic restoration was made.

Introduction

In modern dentistry, implant placement becomes an unavoidable procedure in rehabilitation of partially or completely edentulous patients. The rapid development of dental implant surgery and new achievements significantly contribute to clinical workflow (). Modern trends include reduced duration of total rehabilitation process, minimally invasive surgical protocol and increased precision of dental implant placement. A correct implant positioning poses a major challenge in modern dentistry and mismatch between the planned and final implant position is one of the most common treatment complications (). Unsatisfactory direction of the implant placement falls within the category of prosthetic complications which results in aesthetic and functional complications (). A correct implant placement allows for a favorable force transfer to implants and future prosthetic suprastructure and, as a consequence, an appropriate aesthetic outcome. Such an approach is called prosthetically driven implantology (). It is a precise surgical guide or a template that is a ‘‘transmission device’’ which enables the implant placement in the intended position as accurate as possible (). The development of information technology (IT) has made an outstanding contribution to all branches of the medical profession, including dental implants. The introduction of the Cone Beam Computer tomography (CBCT) into practice has enabled a very high-quality three-dimensional representation of craniofacial structures. The development of appropriate software to plan the setting of dental implants, in addition to CBCT, gave a completely new guidance in implant therapy. Finally, surgical guides made by CAD/CAM (Computer Aided Design/Computer Aided Manufacturing) technology have been developed. They are produced by combining all data generated in the preparatory phases of implant therapy ().

Case study

A woman aged 60 came into dental office to resolve a single tooth loss in regions 15 and 24. After a detailed medical and dental history had been taken, the patient was found to be healthy and there were no contraindications for implant therapy. Orthopantomograph analysis and clinical examination showed a lack of transversal space in the regions of implantation (Figure 1). In order to continue the planning and conduct of therapy, 3D scans and the interocclusal record were taken using Primescan (Dentsply Sirona, Charlotte, North Carolina, USA) and CBCT images of the upper jaw. According to CBCT data, the mesiodistal width in region 15 is 6.20 mm and in region 24 is 6.13 mm (Figure 2). Because of the narrow vestibulooral and mesiodistal area of implantation, a prosthetically driven implant therapy using the M-Guide system (MIS Implants Technologies Ltd., Bar-Lev Industrial Park, Israel) was selected.

Figure 1

Panoramic radiograph at first visit - lack of transversal space in the regions of implantation

Figure 2

CBCT image - mesiodistal width in region 15 is 6, 20 mm and in region 24 is 6, 13 mm

The treatment plan was the prosthetic restoration involving the placement of two MIS C1 implants (MIS Implants Technologies Ltd., Bar-Lev Industrial Park, Israel) of 3.30 mm diameter and 11.50 mm length in areas 15 and 24 and the fabrication of zirconium oxide crowns. The course of all the interventions was explained to the patient, and she accepted the recommended treatment and signed informed consent.

In the laboratory, digital wax-up of the future crowns was done and they were placed in an ideal aesthetic and functional position. The data were exported in stereolithographic (STL) format. Data files with wax-up; CBCT and patient data form were sent to the MIS M-guide center. In coordination with the surgeon and the prosthodontist, the ideal surgical and prosthetic position of the implant in MIS M-soft software was planned (Figure 3) and a surgical guide was designed using 3D printing technology. The guide came to the office sterilized and ready for use (Figure 4). After checking whether the guide fitted (Figure 5), the surgery was initiated by a guided implant protocol. The ''Tissue punch'' incision allows the implantation without raising a flap, so-called flapless technique (Figure 6). The preparation of the bone and implantation was carried out by a protocol which was partly different from a conventional technique without a guide. The difference is that longer drills corresponding to the dimensions of the guide were used in the guided implant protocol and the whole process was performed using only two drills. Bone preparation began with a ''bone mill’’ (MIS) drill to flatten the alveolar ridge, thus increasing the accuracy for the rest of the drilling sequence. Further preparation was performed using ''guided pilot drill'' and ''guided conical drill’' (MIS). The mere implantation of implants into the bone was also made through a guide, using a so-called fully guided protocol (Figure 7). After implantation, Implant stability Quotient (ISQ) was measured with Penguin RFA (Integration Diagnostics Sweden AB, Göteborg, Sweden) and a high primary stability value of 75 (Figure 8) was obtained. Immediately after implantation, a temporary suprastructure (polyether ether ketone [PEEK] abutment) and temporary crowns (milled polymethyl methacrylate [PMMA]) were placed (Figure 9). After a period of osseointegration, the definitive prosthetic restoration was made. The patient was referred to a control orthopantomograph image immediately after having undergone the surgical part of the treatment (Figure 10).

Figure 3

M-soft digital planning - the ideal surgical and prosthetic position of the implant

Figure 4

Surgical guide (M-guide)

Figure 5

Surgical guide checked in mouth

Figure 6

''Tissue punch incision’’ – flapless technique

Figure 7

Implantation – fully guided protocol

Figure 8

Measuring the Implant Stability Quotient -ISQ

Figure 9

PEEK abutment and PMMA crown

Figure 10

Control panoramic radiograph immediately after surgical treatment

Discussion

Computer-guided implant surgery has numerous advantages for both the doctor and the patient. The procedure takes less time with consequently less post-operative problems such as pain, bleeding and edema. The implantation can be done without raising the mucoperiosteal flap (flapless technique), resulting in reduced resorption of the alveolar ridge, preservation of interdental papillae and gingival margins of adjacent teeth (). Temporary or permanent prosthetic restoration can be designed and fabricated prior to surgery and, in cases of immediate loading, the total time of implantoprosthetic therapy is reduced ().

Advantages that contribute to the dentist can be seen in immensely detailed diagnostics and precise planning of therapy. Thanks to computer technology, the virtually planned position of the implant is transferred to the surgical field, which reduces the possibility of errors and injuries of important anatomical structures. Such an approach enables a predictable and safe outcome of implantation ().

Reports in the literature have noted some complications related to computer-guided implant therapy and it is of crucial importance to highlight possible deficiencies of such a therapy so that clinicians can determine the indications and contraindications for this therapy. Colombo et al. have claimed that the advantages of computer guided implant surgery do not have substantiated evidence recorded in the recognized scientific literature, but are mainly based on the clinical experience of certain doctors (). No statistically significant difference in implantation survival and frequency of complications between conventional and computer guided implant therapy was observed in this review. There was a difference in post-operative complications, such as pain and edema, which are more common in the conventional method without a surgical guide (). Schneider et al. have observed that the type of computer guided technique, the number of missing teeth and the type of guide support in the patient's mouth could be main causes of the discrepancy in precision (). Since surgical protocols consist of a large number of steps, the possibility of error increases in accordance with the number of steps and the resulting error is a sum of the following:

1. CT, layering and data storage,

2. Planning and printing of a guide

3. Inadequate stability and displacement of the guide during the rotation of the drill,

4. Inadequate fitting of a drill within a cylinder,

5. Mucosa thickness

6. Patient movement,

7. Software errors ().

The error in implant positioning can be measured in two ways, directly and indirectly. The error is measured directly by comparing the CBCT image before and after the implantation. In indirect mode, an impression is taken or healing abutments mounted on the desired implants are scanned (). Parameters taken into account in assessing the deviation of the planned and obtained implant position are: linear deviations at platform and apex level, vertical deviations in implantation depth, and angular deviations. Tahmaseb et al. showed the following average deviations: on an implant platform of 1.12 mm, at the implant apex level 1.39 mm, in the implant angulation 3.89 ° (). D' haese et al. mentioned angular deviations of 2.71 ° – at the level of the implant apex 1.6 mm and at the level of the implant platform 1 mm (). Due to these data and the fact that a large number of steps give a proportional error possibility, it is of paramount importance to assess whether there is and what is the indication for a computer-guided implant surgery. It is logical to conclude that such a therapy is recommended in cases of immediate proximity of important anatomical structures and in a demanding prosthetic aspect of the therapy. Further development of artificial intelligence and progress in computerization will make the planning and conducting of therapy even simpler and safer. For clinicians, as well as patients, an unavoidable reduction in the number of steps will bring computer-guided implant surgery closer to everyday dental practice ().

Conclusions

Computer guided implantoprosthetic therapy was developed primarily in order for the clinician to reproduce the planned therapy as accurate as possible. It is precisely the accuracy of transferring the planned rehabilitation to the surgical field that is the main parameter taken into account in the evaluation of the therapy. An overview of modern literature has showed that there are no statistically significant differences which would prove that computer-guided implant therapy is superior to conventional therapy. Nevertheless, there are advantages to be taken into account when planning and implementing therapy: minimal invasiveness of flapless technique, faster post-operative healing, optimal positioning of implants and the possibility of an immediate loading. However, the financial factor should not be omitted. Computer guided therapy is much more expensive than conventional therapy without surgical guide. Taking into account all of the above, it is concluded that the properly indicated and implemented computer-guided implant surgery is safe and it provides predictable results.