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ePaper created 2017-08-25, 17:58:13 | version 1.38.0
| case report guided implant reconstruction rated curettes and serrated round burs. Following the simulated plan, osteotomies were prepared for four implants to support an overdenture. The two middle implants were 4.0 mm diameter by 13 mm in length, and the two distal implants were 3.5 mm by 13 mm in length approximately 1–2 mm below the bone crest as per manufacturer’s protocol (AnyRidge, MegaGen Implants). Each implant was well fixated due to three factors: (1) the anticipated thickness of the buccal and lingual cortical plates; (2) the apical length of the implants engaging native bone; and (3) the thread design of the implant type (Figs. 16a & b). Each implant was tested by resonance frequency analysis (RFA) to document implant stability with an implant-specific SmartPeg to record an implant sta- bility quotient (ISQ) value (IDx Osstell). Clinicians might consider the importance of assessing implant stability for every implant placed using a non-de- structive and objective protocol well-documented in the scientific literature. Additionally significant and differing entirely from insertion torque values is that ISQ values can monitored over time which is espe- cially important when a two-stage surgical approach is anticipated as in this case example. To fill the voids around the implants and over the alveolar crest, a small particle sized synthetic resorb- able calcium apatite grafting material was used (OsteoGen, Impladent Ltd.; Fig. 18a). The implants were then buried under layers of platelet-rich fibrin (PRF), and the soft tissue approximated to cover the site with tension-free closure (Fig. 18b). Post- operative healing was unremarkable. After the site was allowed to mature for three months, a midline incision carefully split the narrow band of keratinised tissue to uncover the grafted site and the underlying four implants, which were all covered with a small layer of immature bone. Once fully exposed, each implant was once again fitted with a SmartPeg to assess an ISQ value, which was then compared with the initial values to determine the progress of osseointegration and to confirm implant stability (Figs. 19a & b). The ability to measure stability over time provides invaluable information for the clinician about the health of each implant. A favour - able ISQ value imparts a level of confidence and knowledge of when an implant can be loaded and restored. Healing collars were positioned to allow for the soft tissue to be approximated and sutured. The patient’s initial desire was to help relieve the pain associated with a denture that was not retentive due to the topography of the arch and proximity of the mental nerve to the alveolar crestal bone. The re- storative phase continued with the impression phase, and placement of overdenture abutments to secure Fig. 21 Fig. 22a Fig. 22b Fig. 21: PreForm software designing supports to fabricate two separate cant issues in the placement and the ability to stabi- lise the four implants that were eventually placed. mandibular models. Figs. 22a & b: The virtual surface model (a), and the actual 3-D printed model (b). 30 CAD/CAM 3 2017 Based on the CBCT data and interactive treatment planning simulations, it was elected to complete the surgical placement of four implants in the anterior symphysis in a ‘diagnostic-freehand’ manner. The an- atomical landmarks were clear and allowed accuracy of implant positioning. The knife-edged ridge re- quired a full flap surgical approach (Fig. 13). The broken drill was immediately located lingual to the alveolar crest embedded in the soft tissue. Appar- ently the drill deflected off the sharp ridge into the floor of the mouth, and the torque caused the drill to break. Fortunately the drill did not cause any immedi- ate complications as the floor of the mouth contains many vessels, which if perforated, could have resulted in a sublingual hematoma. The remaining broken drill as seen in Figure 14 was easily retrieved. Once the offending element was removed, the plan was to reduce the knife-edged ridge to gain appropri- ate width for implant placement. The reduction was accomplished in a free-hand method based upon the position and location of the mental foramen on either side of the symphysis. Based upon a thorough review of the CBCT scan data the expected hollow area of bone in the anterior symphysis was exposed (Fig. 15). Prior to implant placement, the soft tissue in the anterior symphysis was carefully removed with ser-