Restoring Mandibular Single Teeth
Inclusive Tooth Replacement Solution
with the
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W
hile the prosthetic rehabilitation of full-arch cases provides a tremendous service for the patient and can be very professionally rewarding for the clinician, single tooth replacement is by far the most common implant restoration. Restoring single posterior teeth with implants provides a viable treatment option and has been well documented.1-5 Of the single posterior teeth, the first molar, or “money tooth” as termed by Dr. Curtis Jansen, very often requires replacement.6 At the Glidewell Laboratories operatory, 59 percent of the single Inclusive® Tapered Implants placed have been in the posterior mandible.One of the most obvious concerns when placing implants in the posterior mandible is identifying and avoiding the inferior alveolar nerve (IAN).7 This can be accomplished through the use of appropriate radiography and proper planning.
Bradley C. Bockhorst, DMD
Figure 3: View of mandibular arch with proposed implant trajectory Conventional implant planning typically involves the use
of a periapical radiograph (PA) and/or a panoramic film. The drawback to these types of two-dimensional images is distortion. The PA should be taken with a paralleling tech-nique to avoid vertical distortion as much as possible. A radiographic marker of known diameter (e.g., 5 mm ball bearing) can be used to determine the distortion in the planned implant site. The marker is measured on the film to determine the distortion factor in that area. A transpar-ent overlay can be used as an aid to determine the correct implant selection (Fig. 1).
Another option is a CT scan. Cone beam scanners provide a three-dimensional image and a precise method for identifi-cation of the IAN.8 The patient’s scan can be imported into planning software, the mandibular canal identified, and the implant placed in a virtual environment (Fig. 2).
In the case presented here, the canal was well differentiated and identified. The mandibular canal is typically identifi-able. However, there are situations where the cortical bone surrounding the canal is not dense and therefore does not show up radiographically. These cases present a significant challenge. One rule of thumb for first molars is to not drill deeper than the roots of the adjacent teeth.
An optical scan of the model provides a clear view of the anatomy of the teeth and the soft tissue (Fig. 3). The appropriate-sized implant is placed within the confines of the available bone (Fig. 4). It is important to be aware that the drills are approximately 1 mm longer than the stated length of the implant. The trajectory of the implant is aimed to-ward the opposing stamp cusp through the center of the occlusal table.
surgEry
The osteotomy should be prepared with the aid of a surgical or prosthetic guide. The prosthetic component of the Inclusive® Tooth Replacement Solution is a traditional surgical stent designed to convey the ideal position of the implant platform from the restorative perspective (Figs. 5, 6). By starting the osteotomy using this guide, the implant will be inserted in the appropriate location to take advantage of the custom temporary abutment and BioTemps® provisional crown. The prosthetic guide is intended for prosthetic reference only, and does not take into consideration any anatomical landmarks or contraindications. This guide should be used in combination with the radiographic and clinical information to determine the best position for the implant.
A surgical guide based on the virtual plan utilizing a CBCT scan of the patient provides the option of drill depth and angulation control. Based on the amount of guidance desired, a surgical guide can be produced that guides the pilot drill. Subsequent drilling with progressively wider
Figure 1: Implant radiographic template for Inclusive Tapered Implants
Figure 7: Universal SurgiGuide
Figure 8: Universal SurgiGuide in situ
Figure 4: Cross-sectional view of proposed implant site
Figure 5: The Inclusive Tooth Replacement Solution prosthetic guide
Figure 6: Prosthetic guide in situ
surgical drills (as needed) and implant placement are performed freehand.
If additional guidance is needed, Universal SurgiGuides (Ma-terialise Dental; Glen Burnie, Md.) are available (Figs. 7, 8). In these cases, all the drills can be guided. The implant is placed freehand once the osteotomy has been created. At the time of placement, a custom healing abutment can be delivered (Figs. 9, 10). The custom healing abutment allows you to start anatomically sculpting the soft tissues at the time of surgery.
A custom temporary abutment and BioTemps crown also are provided with the Inclusive Tooth Replacement Solu-tion. If high primary stability is achieved and the crown is taken well out of occlusion, the implant can be temporized at the time of surgery. Due to the occlusal forces that can be exerted in the molar region, another approach would be to utilize the custom healing abutment at the time of surgery and provisionalize the case at a later date.
Figure 10: Custom healing abutment in place with access opening sealed
Figure 11: Custom temporary abutment and BioTemps crown
Figure 12: After adjustments, a hole is drilled through the crown and the crown cemented to the abutment.
Figure 9: Inclusive Tooth Replacement Solution custom healing abutment
tEMporIzAtIoN
Temporization utilizing the Inclusive Tooth Replacement Solution consists of seating the custom temporary abut ment, then relining and cementing the BioTemps provisional crown
(Fig. 11). If a screw-retained temporary is preferred, after
adjustments are made, an occlusal hole is drilled through the crown (Fig. 12). The abutment and internal surfaces are
roughened up to help create mechanical retention. A guide pin is used to maintain the screw opening, and the crown is luted to the abutment with permanent cement. The crown-abutment assembly is then delivered to the implant (Fig. 13), and the abutment screw is tightened to 15 Ncm (Fig. 14).
The occlusal screw is covered with a piece of Teflon tape and the access opening sealed with composite (Fig. 15). The
crown should be out of occlusion (Fig. 16).
FINAL IMprEssIoNs
The final impression is made with the Inclusive Tooth Replacement Solution custom impression coping (Fig. 17).
The custom impression coping allows you to transfer the position of the implant as well as the soft tissue contours to the master cast. The custom impression coping is seated on the implant and the screw is tightened (Fig. 18).
The access opening is sealed with soft wax to prevent impression material from flowing into the coping (Fig. 19).
The closed-tray impression is made following standard technique. When the material has set, the impression is pulled. The impression coping is removed and replaced with the healing abutment or provisional restoration. The shade is selected (Fig. 20) and clinical photos are taken. A bite registration and impression of the opposing arch are made. The pre-populated Inclusive Tooth Replacement Solution lab prescription is filled out and the case sent to the lab.
LAborAtory FAbrICAtIoN
Upon receipt, the lab will mount the custom impression coping on an implant analog (Fig. 21) and reseat it back
into the impression (Fig. 22). A soft tissue model will be
poured (Fig. 23), the case articulated, and the final
resto-ration fabricated.
Based on the clinician’s preference, a cemented or screw-retained prosthesis can be ordered. In this case, the cemented restoration consisted of an Inclusive® All-Zirconia Custom Abutment (Figs. 24a, 24b) and an IPS e.max® crown (Ivoclar Vivadent; Amherst, N.Y.) (Fig. 25). An acrylic jig is
fabricated to aid in seating the abutment (Figs. 26a, 26b).
FINAL DELIvEry: CEMENt-rEtAINED CroWN
When the healing abutment or provisional restoration is removed, the soft tissues will have healed to more
Figure 13: Seated provisional restoration Figure 17: Custom impression coping
Figure 14: The abutment screw is tightened
Figure 15: The occlusal access opening is sealed
Figure 16: The temporary crown is out of occlusion
Figure 18: The impression coping is seated
Figure 19: The screw access opening is sealed with soft wax
Figure 25: Inclusive All-Zirconia Custom Abutment and IPS e.max crown Figure 22: Assembly reseated into impression
Figure 23: Soft tissue model
Figures 24a, 24b: Inclusive All-Zirconia Custom Abutment
Figure 21: Custom impression coping mounted on implant analog
anatomically correct contours (Fig. 27). The abutment is seated utilizing the jig (Fig. 28) and the screw tightened to 35 Ncm (Fig. 29). The jig is then removed (Fig. 30). The crown is seated and the margins and interproximal and occlusal contacts are checked (Figs. 31a, 31b). Any necessary adjustments are made. There should be light centric contact with a firm bite and no lateral contacts. The interproximal contacts should be light. The abutment screw is tightened once more to 35 Ncm, and the access opening sealed with a piece of Teflon tape. The crown is cemented in place with RelyX™ Unicem Self-Adhesive Resin Cement (3M ESPE; St. Paul, Minn.). All excess cement must be meticulously removed. A PA was taken to verify complete seating and cement removal (Fig. 32).
FINAL DELIvEry:
Ips E.MAx sCrEW-rEtAINED CroWN
If a screw-retained crown was selected (Figs. 33a–33c), the one-piece restoration is seated on the implant (Fig. 34). The abutment screw is tightened to 35 Ncm utilizing the jig
(Fig. 35). The interproximal and occlusal contacts are
checked and adjusted as needed (Fig. 36). The screw access opening is sealed with a piece of Teflon tape and an occlusal composite (Fig. 37).
suMMAry
Replacement of missing mandibular molars with single-tooth implant-borne restorations provides many benefits over fixed partial dentures. It avoids having to prep adjacent teeth, it makes hygiene easier for the patient, and it allows for flexure of the mandible.2 The osteotomy can be created conventionally or through a guided surgical procedure. The Inclusive Tooth Replacement Solution provides the components to simplify the restorative process and provide a superior final restoration for this common restoration. IM
Figures 33a–33c: IPS e.max screw-retained crown Figure 30: The jig is removed
Figures 31a, 31b: After adjustments, the IPS e.max crown is cemented in place
Figure 32: PA verifying seating and cement removal
Figures 26a, 26b: Acrylic abutment seating jig
Figure 27: The provisional restoration is removed
Figure 28: The abutment is seated with the jig
Figure 34: Abutment screw tightened utilizing jig
Figure 35: IPS e.max screw-retained crown seated
Figure 36: Occlusion verified
Figure 37: Access opening sealed with composite
rEFErENCEs
1. Becker W, Becker BE. Replacement of maxillary and mandibular molars with single endosseous implant restorations: a retrospective study. J Prosthet Dent. 1995 Jul; 74(1):51–55.
2. Misch CE, Misch-Dietsh F, Silc J, Barboza E, Cianciola LJ, Kazor C. Posterior implant single-tooth replacement and status of adjacent teeth during a 10-year period: a retrospective report. J Periodontol. 2008 Dec;79(12):2378-82.
3. Misch CE. Endosteal implants for posterior single tooth replacement: alternatives, indications, contraindications, and limitations. J Oral Implantol. 1999;25(2):80-94. 4. Ekfeldt A, Carlsson GE, Börjesson G. Clinical evaluation of single tooth
resto-rations supported by osseointegrated implants: a retrospective study. Int J Oral Maxillofac Implants. 1994 Mar-Apr;9(2):179–83.
5. Muftu A, Chapman RJ. Replacing posterior teeth with freestanding implants: four-year prosthodontic results of a prospective study. J Am Dent Assoc. 1998 Aug; 129(8):1097–102.
6. Jansen C. Presentation given at the Academy of Osseointegration 2012 Annual Meeting, Phoenix, Ariz.
7. Anderson LC, Kosinski TF, Mentag PJ. A review of the intraosseous course of the nerves of the mandible. J Oral Implantol. 1991;17(4):394-403.
8. Alhassani AA, AlGhamdi AS. Inferior alveolar nerve injury in implant dentistry: diag-nosis, causes, prevention, and management. J Oral Implantol. 2010;36(5):401-7. Epub 2010 Jun 14.
