CLINICAL CASE Anthogyr Guiding System®

Dr. Benoît PHILIPPE Maxillofacial Surgery drbp@dr-benoit-philippe.fr

Dr. Laurent SERSImplantologylaurent.sers@wanadoo.fr

COMPUTER-GUIDED IMPLANTOLOGY (CGI) & STEREOLITHOGRAPHIC SURGICAL GUIDES USING SIMPLANT® & ANTHOGYR GUIDING SYSTEM

Part 1: General principles of CGI, Presentation of SimPlant®, Anthogyr Guiding System surgical kit.

Part 2: Operating sequences & surgical protocols.

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Part 1 General principles of CGI, Presentation of SimPlant®, Anthogyr guiding System

surgical kit

The use of computer-guided implantology (CGI) and stereolithographic surgical guides significantly improves effectiveness and safety of the procedures in terms of preservation of anatomical structures, accuracy, aesthetics and biomechanics. However, for practitioners the challenge is the same because advanced technologies are constantly evolving. Therefore, not only do they need to have a good grasp of the techniques but they must also keep up with new developments. The primary objective of the authors is to emphasize the general principles of CGI and the importance of surgical guides, and also to share their experience with the SimPlant® Pro software and proprietary Anthogyr Guiding System surgical kit.

Computer-guided implantology (CGI) and stereolithographic surgical guides allow visualization of implant planning and full control of implant placement.Thanks to controlled drilling (i.e. drill position on the alveolar ridge, and drill orientation) introduced in the late eighties, it became easier to prevent power instruments from slipping on thin ridges or in variable bone interface density [1, 2]. Later on in 2001, a milestone was reached by Tardieu and Vrielink with control of drilling depth using stop drills, and control of tapping and implant placement which have since been performed using stereolithographic surgical guides. This allowed to achieve high-precision positioning with an unrivalled 0.2 to 0.5 mm accuracy [3, 4]. Despite a certain degree of scepticism towards this pioneering concept, all schools of thought and dental implant manufacturers gradually adopted it. CGI soon became a general trend and each implant manufacturer developed its own surgical kit. But, in daily practice some of them proved to be difficult to use. Design easy-to-use, effective and accurate instruments, here was the new challenge for R&D teams. This article includes two sections: in the first one, we will focus on the general principles of CGI and will provide a good insight of the knowledge required to perform CGI, and we will present the Anthogyr Guiding System®. This system features a unique contra angle handpiece with a depth-control stop. It is an ergonomically designed tool that allows full control of the desired drilling depth. In the second section, we will describe the surgical protocols for mucosa-supported, bone-supported and tooth-supported procedures, based on typical clinical cases.We will present the SimPlant® Pro16 software which is indispensable for treatment planning. Finally, we will describe the main flap and flapless surgical techniques (using any type of surgical guide) based on several representative case reports.

1 - General principles of CGI

There are typically two types of surgical procedures: open flap and flapless (transmucosal) procedures.

As regards surgical guides, several types of guides can be made using stereolithography depending on the clinical situation and surgeon preferences: mucosa-supported, bone-supported, tooth-supported guides, tooth- and mucosa-supported guides, tooth- and bone-supported guides [5]. Any loading strategy is acceptable:w True immediate loading - The provisional is fabricated either

traditionally by a laboratory technician or using CAD/CAM technology before the procedure, and it is placed in the operating room (OR);

w Early functional loading - The provisional is fabricated before or after surgery and is placed within a few hours or days following surgery;

w Delayed loading - The final prosthesis is fabricated and placed in the patient’s mouth after a healing period of 2-4 months.

2 - Presentation of the software, tools & instruments

SIMPLANT® PRO16 SOFTWARESimPlant® Pro16 can be installed on any PC or Macintosh computer (with the Apple Boot Camp software). As regards system requirements, one needs a minimum of 4 GB of RAM, and a graphics card with 1 GB of video memory. The most popular versions are Simplant OneShot (intended for one time use) and Simplant Pro.

SURGICAL GUIDESThe surgical guides made by Materialise Dental® (Leuven, Belgium) are fully compatible with the Anthogyr surgical kit (Anthogyr Guiding System®) and with Axiom® implants. Materialise surgical guides are fabricated from USP Class IV resin using a stereolithography process and must be cold sterilized. These guides feature:w Metal tubes for easy drilling, tapping, and implant placement.

These tubes are meant to reinforce the stainless steel drilling cylinders which receive same-diameter drills and implants. These cylinders are effective in preserving integrity of the guide during drilling and preventing ingression of resin material into the implants. Cylinders are 4 mm long with an inner diameter (ID) of 4.2 mm for 3.4 and 5.0 mm diameter implants and 5.2 mm for 4.6 mm diameter implants;

w Additional tubes for adjunctive screw fixation. The inner stainless steel cylinders are designed to accommodate fixation screws for the Anthogyr Guiding Sytem®;

w Tiny holes in the side wings of the guide enhance irrigation during drilling. As surgical guides are custom manufactured for each patient, each guide is supplied with a step-by-step protocol together with detailed information on the instruments to be used (and their appropriate diameters and lengths). The surgical guide manufacturing process used at the Materialise Dental® Leuven facility includes two distinct phases:• First phase is a fully automated process. A tank is filled with

photosensitive resin. A dual laser beam is projected onto selected regions of the resin surface. When the laser hits the resin, the resin layer solidifies. This process allows fabrication of 3D models (anatomic model) and surgical guides;

• Second phase is handled manually. The laboratory technician inserts the drilling cylinders into the metal tubes. The inner diameter (ID) of each cylinder ranges from 4.2 mm to 5.2 mm and corresponds to the implant/chuck assembly diameter plus clearance.

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Fig. 2 - Cortical pilot drill and spoon for 4.2 mm and 5.2 mm cylinders.

Fig. 1 - Gingival cutter for use with the contra angle.

Fig. 3 - Reamer drills in 3 diameters and 2 lengths. The working part is the apical portion of the twist drill.

Fig. 4 - 3 tap diameters which match the 3 Axiom® implant diameters (3.4, 4.0 and 4.6 mm).

Fig. 5 - Stop system on the head of the contra angle.

Fig. 6 - Sliding centering sleeve and reamer drill for use with the contra angle.

UNIQUE ANTHOGYR GUIDING SYSTEM® CONCEPT & SURGICAL KITThe Anthogyr Guiding System® surgical kit includes some of the instruments and components which are commonly used in computer-guided implantology:w Gingival cutters for use with the contra-angle in flapless

surgery, available in two different inner diameters: 3.7 mm for 3.4 mm and 4.0 mm implants, and 4.7 mm for 4.6 mm implants (Fig. 1);

w 2 mm diameter cortical pilot drills available in two lengths, 21 mm and 25 mm, and spoons. The latter are effective in maintaining axial alignment of pilot drills inside the metal tubes (Fig2);

w Reamer drills available in 3 diameters: 2.9, 3.5 and 4.1 mm (for use with 3.4, 4.0 and 4.6 mm diameter implants respectively), and in 2 lengths, 21 and 25 mm. The shorter one (21 mm) is ideal for hard-to-reach posterior regions. The longer one (25 mm) is most useful in intermediate edentulous sites (Fig. 3);

w Taps are available in 3 diameters: 3.4, 4.0 and 4.6 mm and 2 lengths, 21 and 25 mm (Fig. 4).

In addition to these conventional instruments, the Anthogyr Guiding System® surgical kit has some special features including:w A unique contra angle handpiece with an adjustable stop

system that significantly reduces the number of twist drills in the surgical kit (Fig. 5). The stop can be adjusted to the desired depth, using the laser markings (6.5, 8, 10, 12 and 14 mm) on the mandrel shafts, and locked.

w Unique axial alignment system - Sliding nuts have been designed to fit onto the twist drill mandrel. Being removable, they provide full intraoperative flexibility. When assembled, they maintain stability of the drill throughout the reaming sequence. This unique feature is an effective alternative to the traditional and rather cumbersome drill keys which may cause bending or fracture of the surgical guide. The sliding nut slides along the mandrel shaft until it contacts the depth-control stop, that is, at the end of each drill sequence. This guarantees axial alignment of the drill at all times during reaming (Fig. 6);

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Fig. 9 - Adjunctive screw fixation for the Anthogyr surgical guide.

w Twist drills and taps with a well-thought-out design: the working part is limited to the apical portion of the instrument. This further facilitates manipulation of the contra angle. Drills and taps have the same color codes as the corresponding implants for immediate identification of the diameters in the OR. The limited number of instruments combined with color coding helps reduce handling and storage errors. Correct selection of the appropriate instrument length significantly reduces the risk of excessive drilling depth;

w 4.2 mm diameter chucks for 3.4 and 4.0 mm diameter implants and 5.2 mm chucks for 4.6 mm implants. The trilobe identification marking and depth markings are clearly visible on the proximal portion of the instrument. The trilobe identification marking is a very efficient and useful anti-rotation feature which eliminates the need for a stop as seen on conventional implant holders. It further avoids the worm screw effect (with resulting thread stripping and loss of initial fixation) which occurs when insertion depth has been reached (Fig. 7). With the mandrel connected to the contra angle, the surgeon can pick up the implant directly from the tray («no-touch method») and securely hold it during transfer to the patient’s mouth without any risk of contamination (Fig. 8);

w Guide fixing screw (fabricated from medical grade titanium) provide secure fixation of the Anthogyr surgical guide and fit the contra angle (Fig. 9).

3 - Scan prosthesis, cone-beam data and planification

The protocol described hereunder has been used for management of a completely edentulous patient with mucosa-supported restoration and immediate loading of provisional.

FABRICATION OF THE SCAN PROSTHESIS & IMPLANT PLANNINGComputer-guided implant surgery (CGI) starts with design and

fabrication of a scan prosthesis in collaboration with the clinician. It is a critical mandatory step which will serve as a basis for implant planning and subsequent surgery.

• Fabrication of a scan prosthesis based on the existing denture (diagnostic set-up) - It is the most realistic and popular method. Resin is mixed with 30% barium sulfate to obtain a homogeneous radiopaque material. Drill holes display as negatives in the image of the scan prosthesis. The base plate of the scan prosthesis that is in contact with the edentulous ridge is a mixture of resin and 10% barium sulfate. It allows evaluation of the thickness of the ridge and gingival profile, while allowing to differentiate between the image of the periodontium and that of the scan prosthesis[6];

• Fabrication of a scan prosthesis using commercially available radio-paque plastic teeth (e.g. Ivoclar®) - The fabrication process is much faster but the resulting template seldom addresses the specific patient requirements due to the fact that the teeth have stereotyped designs (size, shape and curve);

• Dual scan technique - This technique is often used in completely edentulous patients who wear a removable prosthesis which has been designed by their practitioner based on functional and aesthetic criteria and has demonstrated good clinical performance. Radiopaque markers are added to a resin-base removable denture. A high-definition CT scan is taken of the scan prosthesis alone, and a second one with the template in the patient’s mouth (jaws in occlusion). Then, the 3D image of the prosthesis alone is laid over the 3D image of the in situ prosthesis using SimPlant. The radiopaque markers are most helpful to achieve precise overlay (Figs. 10 & 11);

• Virtual teeth - It is a very attractive tool, indeed, but for the time being it is rarely used in daily practice, and this for several good reasons:

w Although it is possible to adjust the height and width of each tooth, the available shapes do not address the anatomic spectrum and therefore seldom meet the needs of the individual patient;

Fig. 7 - Mandrel for use with the contra angle. Depth marking is clearly visible. NO STOP!

Fig. 8 - Mandibular implant placement: the implant holder captures the implant for safe insertion.

Fig. 10 - Resin-base removable denture with embedded radiopaque markers.

Fig. 11 - Overlay of 3D images of the template alone and the in situ template.

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w Correct 3D evaluation of occlusion on a 2D monitor remains a challenge.

However, the tremendous capabilities of the latest CAD/CAM softwares regarding graphics, replication and analysis of the mandibular kinetics should benefit the «virtual teeth», tool which no doubt will soon gain a wide degree of popularity.

DATA ACQUISITION: CT SCAN vs CBCTData acquisition, whether it be with CT scan or CBCT (cone-beam computed tomography), follows a very strict protocol.

Guidelines for a low-dose CT protocol:w Thin-sliced (0.63 mm), high resolution axial images. Slice

spacing is 0.4 mm. Axial scans are obtained parallel to the occlusal plane for the mandible, and parallel to the hard palate for the maxilla;

w The scan prosthesis (with its embedded radiopaque markers) should be placed in the patient’s mouth with the jaws in occlusion. No movement is allowed during the whole procedure. There is no preferred type of occlusion; it depends on surgeon preferences and school trends. True occlusion offers the advantage of allowing perfect visualization of antagonists, but it is associated with a higher incidence of artifacts due to the presence of metal restorations in the opposing jaw. Maintaining the jaws slightly open by using a radiolucent wedge facilitates reading because the images are not disturbed. But the downside is that the opposite jaw does not appear and insertion of the wedge may cause the template to slightly shift;

w Even if thin slices are used for higher diagnostic accuracy, the effective radiation dose is very low and totally harmless for the patient.

Guidelines for a CBCT protocol:w Thin-sliced (0.15 mm) high resolution axial images are

obtained;w As for scan prosthesis positioning in the patient’s mouth or

image overlay (if a dual scan technique is used), the protocol is similar to CT scan.

SEGMENTATION OF IMAGES AND 3D REPRESENTATIONSSegmentation of images is a multiple-step process that can be performed by a practitioner who has a SimPlant Pro software, or by Materialise Dental® engineers after receipt of DICOM files:w Metal artifacts are removed from each 2D image;w 3D representations of the patient’s anatomy are generated

(i.e. mandible, maxilla, teeth, lips etc...). 2D DICOM images are compiled into voxels in order to represent the model in three dimensions; it is called «3D thresholding». The user can select threshold values to show bony structures, teeth or soft tissue. These values correspond to Hounsfield units (HU). The Hounsfield scale has 4,096 grey levels whereas CBCT offers 14,000-60,000 grey levels, depending on the machine used. At the edentulous ridge, the mildly dense gingival tissue is digitally reconstructed by subtraction, based on the scan images of the radiopaque silicone varnish;

w Structures are automatically individualized by the software provided that bone densities are well distinct (e.g. craniomaxillary complex can be displayed separately if the glenoid fossae and the condyles have different bone densities). Otherwise, the IT engineer will have

to do it manually. The same goes for teeth within their sockets. Genuine virtual extractions (so-called «boolean subtractions») can be performed by the IT engineer.

QUANTITATIVE & QUALITATIVE DIAGNOSISAxial, parasagittal and panoramic images, and 3D representations of the patient’s anatomy provide a good insight of the case. The software offers the option to visualize the three images separately or simultaneously. A drop-down menu allows visualization of each image in one millimeter increments.Other measurement and visualization tools are available:w Distance and angle measurements;w Measurement of bone density (HU);w Drawing tool - The surgeon can draw nerves and vessels

(e.g. mandibular nerve, palatine artery which runs posterior to the maxilla). Drawings are very accurate and realistic and greatly help the practitioner visualize the relationships between anatomical structures or detect a pathology;

w Transparency tool - Allows to visualize the anatomical structures or implants inside the bone;

w View navigation - A drop-down menu in 3D models provides access to parasagittal and axial images. This unique virtual dissection tool allows the surgeon to visualize preoperatively the anatomical structures of a given patient (i.e. sinuses, nasal cavities, anterior and posterior palatine pedicles, tooth pedicles, incisive nerves etc...) (Figs. 12 & 13).

Fig. 12 - 3D image of the maxilla. Occlusal view.

Fig. 13 - 3D sagittal view showing the nasopalatine pedicle.

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CASE PLANNINGImplant planningAll the Axiom® implants to be used with the Anthogyr Guiding System® are included in the SimPlant implant library: 3.4, 4.0 and 4.6 mm diameters and 6.5-14.0 mm lengths.The color coding system used in SimPlant for implant diameters allows immediate identification of the corresponding containers and twist drills: red for 3.4 mm implants, yellow for 4.0 mm implants, white for 4.6 mm implants.SimPlant offers two visualization modes: Opacity and Transparency which make it a really user-friendly software, particularly for implant selection and implant planning. With the transparency tool, the surgeon can visualize the implants inside the alveolar bone, in each view (i.e. cortical limits, bone density, axes...).The surgeon can apply translation and rotation to cross-sectional views or 3D objects. This can be done manually using the mouse or track pad or by changing parameters.Having a clear view on the scan prosthesis allows accurate implant positioning according to planning (Figs. 14 to 17).

Several features of the SimPlant software should be emphasized:w Measurement of the density of peri-implant tissue;w Collision detection function - When an implant collides with a vital

structure or another implant, or an implant is too close to another one, a warning message automatically appears on the screen and an audible alert is heard (the safe distance can be defined and set by the practitioner);

Also, it is highly important to be aware that an implant is too close to a structure that must be preserved (i.e. pedicle, cavity...). Therefore, the safe distance must be defined and set by each practitioner for each patient.

Abutment planningAll Axiom® abutments (regular, aesthetic, conical, angled) based on soft tissue thickness and gingival profile are listed.

Planning for surgical guide fixation screwsPlanning process for surgical guide fixation screws is similar to that for implants. A selection of fixation screws is available in the SimPlant software. Fixation screws must be positioned symmetrically, far from the implants and vital structures, and inserted perpendicular (if possible) to the ridge in order to ensure proper positioning and stability of the guide.

Additional planningsA minimum insertion depth of 5 mm is necessary to achieve good purchase in the bone and provide stable fixation of the guide.With SimPlant, it is possible to simulate the creation of a graft volume: inlay graft for sinuses and/or onlay graft.

4 - Conclusion

Good grasp of existing implant planning softwares and surgical instruments is a prerequesite to safe computer-guided implantology (CGI) and safe use of the stereolithographic guides which are now considered as an integral component of the evidence-based knowledge of implant surgery.However, whereas planning softwares are considered as standard tools by dental practitioners for their diagnostic and virtual planning capabilities, stereolithographic guides have not yet gained equal popularity. And yet, in some clinical situations, they demonstrate an undisputable benefit to the patient.

References1. Schwarz MS, Rothman SLG, Rhodes ML, Chafez N. Computered tomography. Part

1. Preoperative assessment of the mandibule for endosseous implants surgery. Int J Oral Maxillofac Implants 1987; 2: 137-114.

2. Sarment D, Sukovic P, Clinthorne N. Accuracy of implant placement with a stereolithographic guide. Int J Oral Maxillofac Implants 2003; 18: 571-577.

3. Tardieu PB, Vrielink L. Implantologie assistée par ordinateur. Le programme SimPlant/Surgicase et le Safe System. Mise en charge immédiate d’un bridge mandibulaire avec des implants transmuqueux. Implant 2003; 9: 15-28.

4. Tardieu PB, Pattjin V. SAFE System and immediate smile. In: Tardieu PB, Rosenfeld A (eds). The art of computered implantology. Chicago: Quintessence Publishing Co., 2009: 177-192

5. Mandelaris GA, Rosenfeld AL. Surgiguide options. In: Tardieu PB, Rosenfeld A (eds). The art of computered implantology. Chicago: Quintessence Publishing Co., 2009: 67-88.

6. Israelson H, Plemons JM, Watkins P, Sory C. Barium coated surgical stents and computer-assisted tomography in the preoperative assessment of dental implant patients. Int J Periodontics Restorative Dent 1992; 12: 52-61.

7. Tardieu PB, Philippe B. Édentement complet maxillaire avec atrophie osseuse. Prise en charge thérapeutique. A propos d’un cas. Partie 2. Phase implantaire et prothétique. Implant 2001; 7: 199-210.

ALTERNATIVE REFERENCE FOR THIS ARTICLE: Philippe B, Sers L. Implantologie assistée par ordinateur et guides stéréolithographiques à l’aide du logiciel SimPlant® et de l’Anthogyr Guiding System®. Principes, présentation, séquences d’exploitation et protocoles chirurgicaux. Implant 2013; 19: 295-303.

Fig. 14&15 - Anatomical relationships between the alveolar ridge and the implant and final prosthesis. Soft tissue thickness can be assessed based on the underside of the prosthesis.

Fig. 16 - Simulated implant placement. Cross-sectional view of the 3D image showing the implant.

Fig. 17 - Simulated implant placement. 3D image. Axial view

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Part 2 Operating sequences and surgical

protocols

Following the description of the principles that govern guided implant surgery, and the introduction of the SimPlant® software program and Anthogyr Guiding System® surgical kit in Part 1, Part 2 will now serve for the authors to discuss the main protocols of guided implant surgery based on three representative case reports involving mucosa-supported, bone-supported and tooth-supported surgical guides.

No matter what the clinical situation implantologists are faced with, they are likely to benefit from computer assistance and stereolithographic surgical guides, whether the procedure makes use of a mucosa-, bone- or tooth-supported surgical guide [1, 2, 3, 4].For the authors, the purpose of the second part of this article is to share their clinical experience and introduce an innovative technique characterised by both its simplicity and its efficiency.

1 - Complete edentulism with mucosa-supported surgical guide

The different phases of the surgical procedure mentioned on the roadmap succeed one another as follows:w Preoperative fitting of the surgical guide. Where no extractions

are required and all implants can be placed simultaneously, the fitting of the surgical guide in the mouth preferably takes place during a preoperative appointment. This procedure involves checking its stability and gingival tolerance, especially the absence of vestibular frenum impingement. A slight reduction of the peripheral edges of the saddle may occasionally be necessary.

w Initial local anaesthesia. Administration of the first local anaesthesia to apply the gingival discs typical of the flapless approach. This consists of extraperiosteal surface infiltration of the attached gingiva to avoid periosteal detachment, which would cause a modification of the gingival profile.

w First fixation of the guide and cylindrical gingivectomies. During the initial fixation of the guide, the screws are not fully tightened in order to save effective anchorage for the second fixation. Cutting of the mucosal cylinders is done at a counter-angle using a gingival drill bit whose diameter varies in line with that of the implant considered, in accordance with the road map. As the drill bit reaches the alveolar cortical bone, this signals the completion of the gingival bore holes and periosteal discs. The screws are then loosened to allow

removal of the guide, which is followed by the removal of the gingival-periosteal discs with gouge forceps. Abundant and thorough flushing ensures that the gingival bore holes are clear (Fig. 1 to 4).

w Second fixation of the guide and completion of local anaesthesia. Deep intraspongious injection of the alveolar bone, whereby the needle is inserted via the bore holes of the first drilling of the screws, precedes full tightening of the bone fixation screws. All of the screws are tightened simultaneously in a gradual and symmetrical manner so as to avoid causing isolated gingival compression and dislocating the guide. Local

Fig. 1: Initial situation

Fig. 2: Positioning of the mucosa- supported guide

Fig. 4: Temporary removal of the guide allows the review of the gingivectomy.

Fig. 3: Gingival cutter mounted at counter-angle. Intraoperative view.

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anaesthesia is administered away from the guide-bearing area.

w Initial drilling. This step is carried out using 2 mm pilot bits stabilised through the guide cylinders by means of the guiding reduction spoon (Fig. 5).

The use of the abutment at counter-angle, set according to the length of the implants (6.5, 8, 10, 12 and 14 mm), provides deep drilling control.w Gradual reaming of the boreholes. This reaming, which is shown on

the roadmap, is based on the diameter of each implant. An implant measuring 3.4 mm in diameter requires the use of a red ring drill bit measuring 2.9 mm in diameter. An implant measuring 4 mm in diameter requires secondary boring with a 3.5 mm yellow ring drill bit. A 4.6 mm implant requires a third reaming step with a third, 4.1 mm white ring drill bit. Thorough and abundant flushing with cold saline and aspiration of each bore hole at each step of the drilling process ensure that these are left completely free from bone debris. Bone debris “packing” could cause blockage of the core drill and result in inaccurate vertical positioning of the implants. As regards depth control, it is effective when the abutment of the counter-angle comes into contact with the centring ring placed on the mandrel of each bit (Fig. 6 & 7).

w It is recommended to perform tapping under copious flushing with cold saline in the presence of type 1 or type 2 bone, or if the bore hole straddles two distinct densities.

w Implant insertion. This step is typically carried out without flushing, at slow speed (between 10 and 35 rev/min) with a torque of between 20 and 40 N. The reference markers, which are placed on the proximal portion of each implant holder and readily identifiable, enable accurate positioning of the implants in the vertical (depth control) and horizontal (in rotation control) planes, without risking

the loss of primary anchorage (destruction of intraosseous turns due to the “worm” phenomenon. (Fig. 8 & 9).

w The bone screws are unscrewed using the special screwdriver to allow removal of the surgical guide (Fig. 10).

w Immediate loading of the temporary bridge, either prepared preoperatively by the technician according to traditional protocols or machined (CAD/CAM) according to the previously described immediate smile protocol [5, 6] (Fig. 11 to 17).

Fig. 5: Transcortical

drilling

Fig. 7: Mounted

abutment at counter-angle

comes into contact with the

centring ring.

Fig. 6: Core drill measuring 2.9 mm in diameter and its centring ring at initial counter-angle.

Fig. 9: The visual

depth marking enables insertion

of the implant without “worm”

phenomenon.

Fig. 8: Guided implant insertion.

Fig. 10: Removal of the surgical guide.

Fig. 11: Placement of conical abutments on the implants.

Fig. 12: Fixed prosthesis.

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2 - Complete edentulism with bone-supported guide

Surgery with a bone-supported guide involves raising full-thickness flaps. This type is worth performing

when a procedure involving the skeletal infrastructure is required at the same time as implant placement: bone screw removal, ridge resection or levelling, lateralisation of the dental nerve, difficult extraction, etc.[7] (Fig. 18 to 22). Several surgical steps differentiate the open- tray procedure from the closed-tray procedure previously described:w The guides cannot be tested in the mouth before the procedure;

however, an informed demarcation of the lateral extensions of the support areas is required at the time of design as insertion may otherwise prove impossible, or conversely, excessive detachment of mucoperiosteal flaps could occur;

w Local anaesthesia is administered in a one-stage surgical procedure;

w Since full-thickness flaps are raised to allow juxtaosseous insertion of the guide, periosteal gingival punches are no longer required;

w Careful periosteal detachment is essential to eliminate any risk of periosteal or mucosal interposition between the skeleton and the bone-supported guide. This is especially recommended in the distal bearing areas (Fig. 23 & 24);

w Deferred implant loading and the associated tissue regeneration period make up the bulk of open-tray procedures.

Fig. 13: Note the satisfactory emergence of the implants.

Fig. 14 & 15: Note the satisfactory emergence of the implants.

Fig. 16: Radiographic inspection.

Fig. 17: End situation. Satisfactory

inspection of lip-tooth relationship during smile.

Fig. 18 & 19: Implant simulation. Sharp, knife-edge ridge requiring resection.

Fig. 20: Ultrasound-guided resection of the occlusal portion of the ridge.

Fig. 21: Removal of resection guide.

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3 - Partial edentulism with tooth-supported guide & deferred loading (single tooth partial edentulism with gaps)

Accurate capture of the dental arch, a process carried out in high-definition based on a hard plaster model and using an optical scanner is a prerequisite for the stability of the stereolithographic guide in the mouth [8] (Fig. 25 & 26).

The use of tooth-supported guides is particularly popular with guided surgery neophytes. There are several factors that contribute to the usability of this procedure:w there is no need to affix the guide to the bone; it can be placed

as and when desired during the procedure, which allows the practitioner to visualise each step of the surgical execution (initial drilling, reaming and implant insertion) (Fig. 28 to 37);

w using a tooth-supported guide allows both open-tray and closed-tray surgery.

Fig. 22: The thickness of the corrected ridge now allows insertion

Fig. 23: Fixation of the guide.

Fig. 24: Satisfactory anchorage of the implants between the two cortices.

Fig. 25: Agenesis of 15 and 25. Initial situation. The hard plaster model allows the scanning of the arch thanks to an optical impression.

Fig. 26: Tooth-supported stereolithographic guide.

Fig. 27 & 28: Initial situation. Preservation of the prosthetic space using a palatal splint.

Fig. 29: Implant simulation. Implants measuring 3.4 mm in diameter.

Fig. 30-32: Surgical sequence through the guide.

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31 32

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4 - Conclusion

A thorough knowledge of implant planning software and surgical instruments is a prerequisite for the safe use of computer-guided implantology and stereolithographic guides, both of which are now well-established scientifically. Though the use of software to analyse data obtained from scanners is a natural choice due to the significant contribution it makes to diagnosis and surgical simulation, the use of stereolithography guides remains uncommon. Not using these may, in some clinical situations, entail “reduced chances” for the patient. The Anthogyr Guiding System® features an original depth and guidance control system that allows the limitation of the number of surgical tools required and better manual tolerance for the surgeon when handling rotary instruments. The reduction in surgical sequences, which decreases handling errors and gives the operator greater ease in addition to preserving primary implant anchorage, should promote the wider use of this technique for greater patient benefit.

References1. Sarment D, Al-Shammari K, Kazor C. Stereolithographic surgical templates for

placement of dental implants in complex cases. Int J Periodontics Restorative Dent 2003; 23: 287–295.

2. Rosenfeld AL, Mandelaris GA, Tardieu PB. Prosthetically directed implant placement using computer software to insure precise placement and predictable prosthetic outcomes. Part I. Diagnostics, imaging, and collaborative accountability. Int J Periodontics Restorative Dent 2006; 26: 215–221.

3. Rosenfeld AL, Mandelaris GA, Tardieu PB. Prosthetically directed implant placement using computer software to insure precise placement and predictable prosthetic outcomes. Part II. Rapid prototype medical modelling and stereolithographic drilling guides requiring bone exposure. Int J Periodontics Restorative Dent 2006; 26: 347–353.

4. Rosenfeld AL, Mandelaris GA, Tardieu PB. Prosthetically directed implant placement using computer software to insure precise placement and predictable prosthetic outcomes. Part III. Rapid prototype medical modelling and stereolithographic drilling guides that do not require bone exposure and the immediate delivery of teeth. Int J Periodontics Restorative Dent 2006; 26: 493–499.

5. Gantz S. Advanced case planning with SimPlant in the art of computer-guided implantology. In: Tardieu PB, Rosenfeld AL (eds). The art of computer-guided implantology. Chicago: Quintessence Books Co Inc., 2009: 200–209.

6. Sers L, Philippe B. Le bridge Immediate Smile®, prothèse implantaire à mise en charge instantanée réalisée en préopératoire par usinage CAD-CAM à partir des données d’une planification SimPlant®. Implant 2012.

7. Rosenfeld AL, Mandelaris GA, Tardieu PB. Clinical cases. In: Tardieu PB, Rosenfeld AL (eds). The art of computer-guided implantology. Chicago: Quintessence Books Co Inc., 2009: 145–148.

8. Gantz S. Advanced case planning with SimPlant. In: Tardieu PB, Rosenfeld AL (eds). The art of computer-guided implantology. Chicago: Quintessence Books Co Inc., 2009: 193–199.

ACKNOWLEDGEMENTS: To Dr Choukroun, who helped us with the literature search. DECLARATION OF INTEREST: the authors confirm that they received consulting fees from Materialise Dental France and Anthogyr, the companies mentioned in this article.BIBLIOGRAPHIC REFERENCING This article may be searched for or quoted under the following reference:Philippe B, Sers L. Implantologie assistée par ordinateur et guides stéréolithographiques à l’aide du logiciel SimPlant® et de l’Anthogyr Guiding System®. Part 2: Séquences d’exploitation et protocoles chirurgicaux. Implant 2013.

Photos credit : Dr Philippe - Dr Sers - Anthogyr

Fig. 33: Guided insertion.

Fig. 34: Radiographic inspection.

Fig. 35: Design of the prosthesis (CAD/CAM).

Fig. 36: Machined prosthesis (CAD/CAM).

Fig. 37: End situation.

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