The intraoral impressions were sent to a commercial laboratory where a final working model was established. The maxillary superstructure with locator attachments was designed and manufactured with CAD/CAM technology (Figure 11). The mandibular unibase with o-ring housings was made using standard dental laboratory procedures (Figure 12). The passivity of the maxillary superstructure was confirmed intraorally using the Sheffield test and a panoramic radiograph. A maxillary/mandibular relationship utilizing baseplates and wax rims, as well as a mold and shade, were taken (Figure 13). A try-in of the final prosthesis was used to confirm vertical dimension of occlusion, phonetics, esthetics, and patient acceptance. The final superstructure was fixated to the implants with retaining screws, torqued to 30 Ncm and locator inserts placed with a cumulative retention value of 7.5 lbs (2 pink and 1 blue). The final maxillary and mandibular overdentures were placed 1 week thereafter (Figure 14 and Figure 15).
Creating synergy with CDIs and SDIs can provide a multitude of treatment alternatives for oral rehabilitation. The size of the implants used depends on various factors of the quality and quantity of bone, as well as biomechanical stress. Site preservation has become a predictable method to optimize bone dimensions and density for future implant sites.8,9
Conventional implants (3.4 to 6.0 mm) are the primary type of endosseous implants used for long-term predictability in implant-retained or supported therapy.10 They can be utilized when the facial-buccal or facial-lingual dimension exhibits a minimal bone of 6 to 8 mm. Conventional size implants remain the primary option for patients who have adequate bone or who accept bone grafting procedures, and who also have financial means.
SDIs (1.8 to 2.9 mm) are an alternative to CDIs when specific criteria are met.11 The major reason for utilizing SDIs is minimal width of bone or space between adjacent teeth in a mesio-distal dimension. In addition, SDIs are indicated for patients who are not candidates for invasive bone grafting procedures due to medical reasons, limited finances, or time. SDIs demonstrate high success in the mandibular arch when retaining removable overdentures.12
The maxilla has demonstrated lower success rates than the mandible in regards to implant therapy. Protocols have been established to enhance success rates as they relate to the mandible.13 These protocols have centered around minimizing stress to the crestal bone, where bone loss is often seen. A critical consideration is utilization of implants with a diameter size greater than 3 mm, which reduces stress at the crest of the alveolar bone due to increased surface area. In addition, increasing the number of implants from four to six demonstrates higher success rates via an increase in cumulative surface area. Implant lengths of 12 mm or greater have exhibited two to three times greater success versus 10-mm lengths. Superstructure design without a cantilever component has demonstrated higher overdenture retention with less resultant crestal bone loss. The elimination of cantilevers in the maxillary superstructure bar reduces stress on the distal terminal implants.
Research has demonstrated positive long-term outcomes with the utilization of SDIs in the mandible.14 Rigid fixation of the implant body at the time of placement is crucial for the osseointegrative process to ensue.15 Secondarily, the auto-advanced technique coupled with a partial osteotomy enhances bicortical stabilization.16 Flapless surgery and immediate load are considerations when utilizing a one-piece SDI.17 However, a full mucoperiosteal flap with a 3-month osseointegrative time period was utilized in this case.