Written by Bill Abbo, DDS, MS, and Sarah E. Miller Thursday, 01 May 2008 00:00
|Figure 1. Initial view of the edentulous area.|
|Figure 2. The preliminary cast.|
|Figure 3. The surgical guide, as received from the production facility.|
When the surgical guide was received in the dental clinic (Figure 3), it was utilized in conjunction with the casts to fabricate a template that illustrates the position of the implants on the cast before the surgery. The possibility for fabrication of custom abutments, as well as provisional restorations prior to the surgery, is a consequence of the reliability found via the planning software and surgical guides. The surgical guide contains all the information necessary for the fabrication of the master cast including the position, size, and angulations of the implants. This makes it possible to accurately fabricate the abutments and the provisional fixed restorations.
|Figure 4. The preliminary cast is sectioned in the area of the proposed implant placement.||Figure 5. The surgical guide is shown fitting passively on the sectioned cast.|
|Figure 6. Guided pins and abutment have been placed into the surgical guide. Surgical guide placed onto the cast, and soft-tissue moulage (PVS) injected onto the internal surface of the surgical guide.||Figure 7. The modified soft-tissue cast with correct positioning of the dental implants.|
|Figure 8. Occlusal view of the endosseous implants placed using the surgical guide.||Figure 9. The zirconia abutments placed on the endosseous implants immediately after surgery and torqued at 35 Ncm.|
|Figure 10. Provisional restoration cemented after surgery.|
The surgery, utilizing a flapless technique, was performed under local anesthetic. External hexagon Bränemark implants were placed: a 4.0x13.0-mm implant in the area of the maxillary left central incisor, and 3.3x13-mm in the position of the maxillary left lateral incisor. The surgical guide was placed in the patient’s mouth, and 2 stabilization pins (designed on the computer software to secure the surgical guide in place) were inserted after creating an opening with a 1.2-mm drill. The first osteotomy site was prepared for the central incisor using the appropriate drilling guides and twist drills. The implant was placed using the prefabricated implant guide. After insertion of the implant, a template abutment was placed (Nobel Biocare) connecting the implant to the surgical guide. This provided additional stability for the guide. The same procedure was performed for the implant located at the site of the lateral incisor. The second implant was placed using the same drilling sequence and guides. After the two implants were placed, the surgical guide was removed (Figure 8). The custom abutments were then torqued to 35 Ncm (Figure 9). After verification of the fit to the abutment margins and the emergence profile was checked, the temporary restoration was cemented in place with zinc oxide eugenol (TempBond [Kerr Corporation]). The occlusion was verified and adjusted to ensure that only contacts in centric occlusion occurred, with no contacts in lateral protrusive movements (Figure 10).
The selection of treatment modalities has always been a dilemma. In the past few years, with the increased use of dental implants, this dilemma has become of greater concern due to the increased variety of treatments, including the possibility of treating edentulous patients with single-unit restorations on implants. The longevity and success rate of restorations are primary concerns for the patient as well as for the clinician. In a study by Romeo,19 cumulative implant survival rates were calculated for im-plants supporting single-tooth prostheses at a failure rate of 4.4% after a period of 7 years. Studies on the longevity of fixed partial dentures have been conducted, and they all reflect a common finding, that the main reason for failure is caries.20,21 Longevity of these fixed partial dentures on natural teeth are determined by the time in service. According to De Backer, et al,22 the 20-year survival rates show failure percentages of 33.8%. From these studies and many others, including case reports,23 clinicians have been performing more and more treatments in the realm of implant dentistry. The clinician has many decisions to make involving issues such as timing, type of loading (immediate loading, delayed loading), type of restorations (screw retained, cement retained), and type of cementation (definitive, temporary). With this new treatment modality, clinicians have a greater and more complete variety of viable options that must be taken into consideration for the treatment of the partially and completely edentulous patients.
The placement of endosseous implants in edentulous areas has proven to be an excellent alternative for replacing single or multiple teeth. With the help of software designed for computer-guided surgery, it is possible to achieve accurate implant positioning and to fabricate provisional restorations, including abutments, before the surgery. These procedures work together to enhance aesthetic and functional results as well as minimize a patient’s time in the dental chair.
- Adell R, Eriksson B, Lekholm U, et al. Long-term follow-up study of osseointegrated implants in the treatment of totally edentulous jaws. Int J Oral Maxillofac Implants. 1990;5:347-359.
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- Lekholm U, van Steenberghe D, Herrmann I, et al. Osseointegrated implants in the treatment of partially edentulous jaws: a prospective 5-year multicenter study. Int J Oral Maxillofac Im-plants.1994;9:627-635.
- Adell R, Lekholm U, Rockler B, et al. A 15-year study of osseointegrated implants in the treatment of the edentulous jaw. Int J Oral Surg.1981;10:387-416.
- Cox JF, Zarb GA. The longitudinal clinical efficacy of osseointegrated dental implants: a 3-year report. Int J Oral Maxillofac Implants. 1987;2:91-100.
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- Romeo E, Lops D, Margutti E, et al. Long-term survival and success of oral implants in the treatment of full and partial arches: a 7-year prospective study with the ITI dental implant system. Int J Oral Maxillofac Implants. 2004;19:247-259.
- Schwartz NL, Whitsett LD, Berry TG, et al. Unserviceable crowns and fixed partial dentures: life-span and causes for loss of serviceability. J Am Dent Assoc. 1970;81:1395-1401.
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- De Backer H, Van Maele G, De Moor N, et al. A 20-year retrospective survival study of fixed partial dentures. Int J Prosthodont. 2006;19:143-153.
- Abbo B, Razzoog M. Restoring the partial edentulous patient in the aesthetic zone using implants and all-ceramic restorations: case report. Dent Today. Dec 2006;25:94-97.
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