IMMEDIATE SMILE® BRIDGE:

A CAD/CAM restoration for immediate loading, based on the Simplant® treatment plan

CLINICAL CASE: ANTHOGYR GUIDING SYSTEM®

Dr. Laurent SERSImplantologylaurent.sers@wanadoo.fr

Dr. Benoit PHILIPPEMaxillo-facial surgeryinfo@dr-benoit-philippe.fr

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The aim of this paper is to present the basic principles, methodology, surgical and restorative protocols of the Immediate Smile® bridge, using the 3D technology developed by Materialise Dental combined with the Anthogyr Guiding System®.

Every computer-assisted surgical procedure (CAS) necessitates an optimized software tool for treatment planning. Following CT scan acquisition, implant simulations can be made through multiplanar reformation of CT images, providing the dentist with an effective dental implant surgical simulator. The aim is to offer a tailored surgical approach using a dedicated guiding system that allows easy transfer of the 3D implant planning onto the patient.What we are presenting here is a novel technology that allows delivery of a CAD/CAM restoration before surgery: the Immediate Smile® bridge. The end of it is to provide the patient with a temporary high-quality screw-retained restoration for immediate loading.

BASIC PRINCIPLES Immediate Smile® bridge: design features

The Immediate Smile® bridge is a temporary CAD/CAM restoration for immediate loading. It is fabricated from a PMMA (polymethylmethacrylate) resin acrylic block, based on a computer-made implant planning.PMMA is a common polymer with proven dimensional stability and mechanical strength which make it a material of choice for dental prostheses.The Immediate Smile® bridge is available in three shades: light, medium and dark. However, for a better aesthetic result, it is worth using a composite layering technique. It is also possible to select the most appropriate tooth shape: rectangle, triangle, or oval shape. Still, the anatomy (i.e. width and height) of the prosthetic teeth should match the design of the radiological guide that will serve as a reference for the treatment plan in Simplant®.The indications for an Immediate Smile® bridge are dependent on the indications for immediate loading [1, 2]: fully edentulous maxillary and mandibular arches, and single missing anterior tooth. Different radiological guide versions (i.e. bone-supported, mucosa-supported, and tooth-supported) are available for the fabrication of the temporary bridge.However, there are a few limitations to this technique:• a minimum of two implants is necessary to support three prosthetic

teeth• posterior extensions are prohibited• pontics are limited to 4 front teeth and 2 lateral teeth• due to the occlusal and masticatory forces that will be sustained by

the prosthesis, the Immediate Smile® bridge must not be worn for more than 6 months.

EQUIPMENT Equipment required for planning

w Radiological guide and AcquisitionsIt is a radiopaque duplicate of the temporary prosthesis. The fabrication protocol is the same as for a permanent prosthesis (i.e. bite registration, mock-up). After it has been accepted by the patient, a functional, esthetic and phonetic try-in is performed, and any necessary adjustments made. If a mucosa-supported radiological guide is used, it may be desirable to reline the guide using FITT® KERR mixed with barium sulfate.Scanning may be performed with the radiological guide in the patient’s mouth or using the dual scan technique [3, 4, 5].

w Simplant® softwareThe Simplant® software has been developed by Materialise Dental6, 7. It reads the data coming from the scanner and generates 3D representations of the patient’s anatomy, thus allowing preoperative planning of the implant placement. At the end of the planning process, all necessary information is available to custom manufacture a stereolithographic (STL) surgical guide for drill guidance and guided implant placement. With Simplant®, the clinician can accurately transfer the results of the planning process to the patient’s mouth [8, 9, 10, 11, 12, 13].Thanks to the axial images, paramedian views, panoramic views, and reformatted CD scans contained in the Simplant® file, a real interactive 3D implant planning can be performed. A safety warning has been designed to alert the clinician when the implant is too close to vital anatomic structures.All commercially available implants can be found in the Simplant® library. The selected implant is properly positioned using varied tools. Several abutment designs (i.e. standard, aesthetic conical, and angled) are also available. This allows the clinician to select the one that best matches the prosthetic plan which is conditional on gum thickness and gum line.Once virtual planning is completed, it is important to save the files before sending them through the Internet to Materialise Dental (Figs. 1, 2, 3, 4). Materialise will send us back the corresponding surgical guide, the Immediate Smile® bridge, a master model which is fabricated stereolithically from resin (Immediate Smile® model) and will accommodate the implant analogs, and a prosthesis duplicate (Radiographic Guide®) which is useful to determine jaw relations and verify the correct occlusion.

5aFig. 1 - CT data loaded into SimPlant can be viewed on the computer monitor.

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w Surgical guideIn the present case, we have used the Anthogyr Guiding System® developed conjointly by Anthogyr and Materialise. The contra

angle features a unique depth-control stop which allows full control of the desired drilling depth.The sliding centering ring that is inserted on the drill ensures perfect axial alignment at all times during the drilling procedure. It usefully replaces the conventional guiding spoons during reaming phases.Placement of the implant is facilitated by the reference marking on the implant holder.Materialise offers a surgical guide solution that can be used with the Anthogyr Guiding System®. It features cylinders that match the diameters of the Anthogyr Axiom® implants. Three types of guides are available: bone-supported guide, mucosa-supported guide, and Tooth-supported guide [14, 15]. Furthermore, the Anthogyr Guiding System® comes with a dedicated surgical kit.

Immediate Smile® bridge

It is a temporary bridge which is fabricated from PMMA (polymethyl-methacrylate) acrylic resin. Fixation is achieved by injecting composite resin into the injection holes located on the labial surfaces of the prosthetic teeth (Figs. 5 & 6).

Immediate Smile® model

The Immediate Smile® model is a master model (Fig. 7) of the upper arch. It is fabricated stereolithically from resin and features insertion paths corresponding to the implant positions as designed in the Simplant® plan. These paths allow guided placement of the implant analogs.The Immediate Smile® model comes with a lifelike silicone soft tissue which represents the patient’s gingiva (visible on the CT images) to help the lab take into account the realistic soft tissue thickness. This way, the analogs are accurately inserted into

Fig. 2 - Implant planning procedure: determination of implant trajectory, determination of optimal anchorage site, selection of the temporary coping.

Fig. 3 - 3D view of the implant position, temporary coping, and overall axial alignment.

Fig. 4 - End of the planning process showing: implants, temporary copings and fixation screws for the surgical guide.

Fig. 5 - Immediate Smile® bridge for replacement of 10 maxillary teeth. Note: small injection holes are located on the labial surfaces of the prosthetic canines.

Fig. 6 - Immediate Smile® bridge. Insertion paths corresponding to the implant positions are designed to accommodate the temporary copings.

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the Immediate Smile® model and level with the gum/bone interface at each implant site. This is why correct selection of the temporary copings is so critically important.The analogs are secured in the Immediate Smile® model using the lateral screws.Once the analogs and abutments are in place, the master model is positioned over the temporary copings for adjustment of the occlusion on an articulator.

Radiologic Guide® model

It is a reproduction of the radiological guide and can be used on an articulator to validate the occlusion (Figs. 8 & 9).It is obtained by stereolithography, an industrial process which uses laser light to induce polymerization of 0.10 mm thick resin layers (i.e. 0.10 mm accuracy).The primary objectives of this guide are double in mouth: adjustment of the occlusion, and transfer of the occlusion to the articulator via a silicone bite record.

METHODOLOGY 1 - Simplant planning

A treatment plan is a prerequisite to any guided surgery [5, 8, 9, 11,

12]. It allows the clinician to determine the ideal location for the implants, and to place the dental implants and temporary copings with accuracy. As previously said, the initial phase is the creation of a radiological guide which is a radiopaque duplicate of the temporary prosthesis.The radiological guide being worn by the patient during the CT scan, good fit is critically important [16, 17, 18]. Proper segmentation of the data is necessary in order to eliminate the artefacts and optimize the quality of the images. Digital planning steps include:1. Identification of the anatomic structures at risk.2. Determination of the ideal position for the implants (i.e. bone

anchorage, axial alignment). Since the scan prosthesis is displayed on the screen, the clinician can visualize in SimPlant the proposed restoration in relation to the underlying anatomy. In some cases, it is necessary to adjust the trajectory of the implant for anatomical reasons. The position and/or orientation of the implant can be changed as needed. Any change is reflected in all the displayed images.

3. Since the clinician can visualize the gum thickness, he/she is able to select the appropriate temporary coping height. As previously said, numerous abutment designs are available in the Simplant® library to choose from.

4. Planning the fixation screws for the surgical guide: sufficient space should be allowed for insertion of the screwdriver.

Once virtual planning is validated, it is important to save the files before sending them through the Internet to Materialise which will provide the corresponding surgical guide, the Immediate Smile® model, the Radiologic Guide® model, and the Immediate Smile® bridge.

2 - Master model

The Immediate Smile® model comes with a lifelike silicone soft tissue which represents the patient’s gingiva, and the appropriate implant analogs. Each implant analog is made of one single piece that replicates both the implant (and its specific location) and the emergence of the temporary coping. The analogs are inserted into the model and secured with the lateral screws. Now, we have an exact replica of the implanted maxillary arch.Lastly, the temporary copings are placed inside the Immediate Smile® model and secured in the analogs with screws (Figs. 10, 11, 12).

Fig. 7 - Immediate Smile® model fitted with its silicone soft tissue. Each analog is secured using a lateral screw.

Fig. 8 - Radiologic Guide® model: a stereolithographic digital cast.

Fig. 8 - Radiologic Guide® model: a stereolithographic digital cast.

Fig. 10 - Immediate Smile® model fitted with its silicone soft tissue. Analogs are secured using the lateral screws.

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3 - Abutment insertion and adjustment of the immediate smile® bridge

The planning data are directly transferred from the software to the machine tool for the fabrication of the temporary bridge, which allows to precisely position the holes for the temporary copings opposite the implant sites.Once the abutments have been screwed in, the Immediate Smile® bridge (ISB) can be tried on. Friction fit points (if any) should be corrected by grinding. Abutments are often higher than the ISB itself; here again, grinding will eliminate the excess material. Each abutment should be carefully adjusted, and its location noted for correct placement during surgery (Figs. 13, 14, 15).

4 - Bite registration and prelimi-nary adjustment of occlusion

First of all, the Radiologic Guide® model is checked against the Immediate Smile® model: they should fit perfectly.Bite registration is performed using the Radiologic Guide® model. The guide is positioned in the patient’s mouth and a bite record is made. Then, the Radiologic Guide® model is positioned on the master model which is mounted onto the articulator (Figs. 16, 17, 18, 19, 20, 21).Occlusion is adjusted using dental occlusion paper with the Immediate Smile® bridge positioned on the abutments. Side shift and propulsion movements are simulated. All premature contacts should be eliminated (Fig. 22).

Fig. 11 - Immediate Smile® model: preparation of the master model. The analogs are correctly positioned and secured. Right lateral view.

Fig. 12 - Immediate Smile® model: preparation of the master model. The analogs are correctly positioned and secured. Left lateral view. Location of the emergence sites of the analogs matches the planning.

Fig. 14 - Adjustment of the ISB/ISM fit with the temporary coping in situ. Correction of the temporary coping height.

Fig. 15 - Temporary copings are properly adjusted. Good ISB fit.

Fig. 13 - Implant analog with temporary coping screwed on.

Fig. 16 - Radiologic Guide® in place. Adjustment of the occlusion.

Fig. 18 - Transfer of occlusion to the articulator.

Fig. 17 - Bite record being taken.

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5 - Surgical procedure

1. Inject a local anesthetic agent into the attached gingiva, taking care to avoid separation of the gum tissue.2. Loosely position the surgical guide in the patient’s mouth, and check fit and stability (Fig. 23).

3. In flapless implant surgery, punch through the surgical guide (not fixated) using the soft-tissue punch. The depth marking on the mandrel of the gingival punch avoids using the contra angle stop (Fig. 24).4. Stability of the surgical guide is provided by the fixation screws. A small amount of anesthetic is injected into each screw hole of the guide prior to inserting the fixation screws.5. Also inject a small amount of local anesthetic away from the support area as anesthetics tend to cause distension of local tissues.6. Perform initial drilling using the 2 mm diameter pilot drills and a guiding spoon. Set the contra angle stop to the desired drilling depth. Insert the guiding spoon into a cylinder, insert the pilot drill into the key, and drill to the desired depth (Fig. 25). Stop drilling as soon as contact is made with the surface of the spoon. Copiously irrigate the osteotomies with cold sterile saline to eliminate all bone debris.7. The next step is the reaming sequence. Slide the centering ring over the drill and connect the drill to the handpiece. Move the stop to the laser marking which corresponds to the planned implant length (Fig. 26). Stop drilling as soon as contact is made with the surface of the centering sleeve (Fig. 27). Do not forget to thoroughly rinse the

drill before inserting it into the next cylinder.8. The third step of the procedure is the placement of the dental implants. The correct insertion depth is identified by the laser marking on the implant holder. Do not force the implant into the bone (Fig. 28).

9. Remove the fixation screws to free the surgical guide.10. Screw in the temporary copings (Fig. 29).

11. Thread the temporary copings onto the conical abutments. Then, position the Immediate Smile® bridge which has previously been adjusted on the articulator (Figs. 30, 31).

Fig. 23 - Surgical guide in place.

Fig. 27 - The stop on the handpiece provides control of the insertion depth of the guided drill.

Fig. 28 - Guided implant placement.

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Fig. 29 - Placement of the straight conical abutment.

Fig. 30 - Temporary copings are threaded onto the implants.

Fig. 22 - Adjustment of occlusion of the ISB.

Fig. 19, 20 et 21 - ISM are mounted onto the articulator + bite record.

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Fig. 24 - Punching sequence.Fig. 25 - Initial drilling using the pilot drill. A spoon is used for guidance. The

stop of the contra angle ensures control of the drilling depth.Fig. 26 - Drilling sequence using the drill fitted with the centering sleeve.

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12. Lastly, secure the Immediate Smile® bridge by injecting composite resin into the intended injection holes, being careful to avoid intrusion of cement into the temporary copings (Figs. 32, 33, 34).

13. Verify again the occlusion. Premature contacts and areas subjected to excessive occlusal forces should be corrected by selective grinding. Fine-tune the end result (Fig. 35).

DISCUSSIONWe have received tremendous positive feedback from the patients regarding both the aesthetic and functional outcomes. Nevertheless, a few issues still need to be addressed.

Surgical procedureThe surgical procedure requires the use of a surgical guide that translates the Simplant® planning. The clinician must be perfectly familiar with computer-guided implantology to perform this type of procedure.

Toughness of temporary restorationsPolymethylmethacrylate (PMMA) resin is indeed a strong material, but it exhibits low resistance to torsional and flexion forces, which makes it prone to fracture. Due to this, there are a few limitations to this technique: posterior extensions are prohibited; lateral pontics are limited to 1 tooth; anteriorly, a canine pontic is authorized provided that reinforcement with Kevlar material is used on the lingual side of incisors.

BondingComposite resin (medium) bonding appears to be effective and safe. No failure has been reported, so far. Application of the composite resin must be performed under visual control to ensure that it surrounds each abutment. It is interesting to note that resin shows higher adhesion to priorily sandblasted temporary copings.

Temporary copingTemporary copings are high precision machined in order to provide perfect fit. Copings are threaded onto the implants. The Immediate Smile® bridge is secured to the copings with composite resin to ensure a passive fit.

Durability of the immediate smile® bridgeBoth the clinician and the patient are aware that the Immediate Smile® bridge is a temporary restoration and should not be worn for more than 6 months. It will then have to be removed and substituted to a permanent bridge.

Pre-prosthetic stepsEach pre-prosthetic step is critical to the outcome of the restoration. The following steps must be strictly followed and validated: • implant planning• in mouth adjustment of ISB fit• transfer to the articulator and adjustment of the occlusion.

Aesthetic resultThe cervical contours are uneven and disharmonious. The interdental spaces should have been fine-tuned. In particular, the interproximal spaces should be open to make the prosthesis feel more natural. PMMA lacks translucency and opalescence, and has a rather monochromatic appearance. However, the possibility to improve the aesthetics of the ISB in the lab (i.e. by removing and then adding and layering composite resin) is a real advantage and yields good results (Fig. 36).

Fig. 32 - ISB is secured by injecting composite resin through the injection holes.

Fig. 34 - Note that the composite resin surrounds each temporary coping.

Fig. 35 - Final occlusion adjustment. View of the Immediate Smile® bridge in place.

Fig. 31 - View of the priorily adjusted ISB in the patient’s mouth.

2237 Avenue André Lasquin74700 Sallanches - FrancePhone : +33 (0)4 50 58 02 37Fax : +33 (0)4 50 937860

www.anthogyr.com

CLINICAL CASE - ANTHOGYR GUIDING SYSTEM

CONCLUSIONThe technology we have described is another milestone in computer-guided implantology and placement of pre-fabricated ready-to-use temporary prostheses. The bridge can be immediately loaded onto the implants and the patient can walk home smiling and feeling safe and comfortable.Owing to the recent boom in cosmetic dentistry, CAD/CAM machining associated with composite resin layering is rapidly evolving. When combined with computer-guided surgery and the Simplant Pro® software, it opens the way towards state-of-the-art implant-supported restorations.However, this type of procedure requires strict adherence to a rigorous protocol and methodology. Furthermore, although numerous innovations have been introduced, one must take into account the unavoidable learning curve for the Simplant Pro® software [19, 20, 21], the surgical technique, and proper placement of the prosthesis, not to mention the correct patient selection.

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ACKNOWLEDGEMENTS: We wish to acknowledge the assistance of Chloé Choukroune in the completion of this paper. The authors report no conflict of interest with the manufacturers of the above mentioned devices.The authors report no conflict of interest with the manufacturers of the above mentioned devices.BIBLIOGRAPHIC REFERENCING : This article may be searched for or quoted under the following reference: Sers L, Philippe B. Immediate Smile® bridge. A CAD/CAM restoration for immediate loading, based on the Simplant® treatment plan.» Simplant®. Implant 2012 ; 18.

Photos credit : Drs L. Sers et B. Philippe - Anthogyr

Fig. 36 - View of the ISB after a composite layering technique has been used by the lab technician.

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