At the beginning of treatment the patient was 48 years old and in good general health. For decades the patient had suffered from a severe, aggressive, generalised periodontitis (type III B) (fig 1), which could be healed completely prior to implant restoration (PerioHealing Concept; fig 2).
Treatment planning
At first the diseased anterior mandible was healed in a regenerative and biological manner and without bone replacement materials, by employing enamel matrix proteins (Straumann Emdogain) for ‘socket preservation’ prior to immediate implantation at 32 and 42 (fig 2). From the digital volume tomogram (DVT) it could already be presumed preoperatively that simultaneous augmentation to provide a less invasive procedure could be dispensed with by precise implantation at soft tissue level, and that a four-unit fully functional composite metal ceramic (CMC) bridge could be inserted without difficulties due to the more stable implant material (Roxolid).
Surgical procedure
Following periodontal healing (fig 3), teeth 32 and 42 were extracted in toto from the healthy tissue without fracturing, in particular of the buccal lamellae. The clinical and radiological examination employing combined depth gauges showed a four-unit anterior bridge to be possible under these conditions with appropriate implementation (figs 4–6). There was also no need for simultaneous bone augmentation (osteogenic jumping distance).
Using the Straumann Narrow Neck CrossFit (NNC) profile drill the crestal bone was expanded minimally in the present type two bone prior to implantation of the two 10mm NNC implants in each site (Ø 3.3mm to 3.5mm; figs 7 and 8). Attention was paid during the implantation of ?the two NNC implants, so that the micro gap could be placed precisely 2mm coronally of the buccal limbus alveolaris, so as not to obtain crestal bone/soft tissue loss following appropriate tissue maturation (tissuedirected implant placement figs 9–11).
The new NNC insertion aid enables perfect aesthetic analysis of the insertion depth in relation to the variable thickness of the peri-implant gingiva (biologic width: 2.25mm – 3.75mm) and can be fixed again in the implant at any time for fine adjustment prior to suturing. This is due to the tapered press fit (fig 12) which allows one to obtain an optimal, biocompatible intrasulcular position of the micro gap following complete healing/remodelling.
During the final alignment of the implants one then needs to again ensure that the semi-spherical recesses on the insertion aids are placed precisely in buccal direction, so that the prosthetic abutment components can be aligned precisely later on. Using 3mm NNC healing caps provides ideal conditions for soft tissue maturation (approximately six months) in combination with an appropriate temporary restoration (figs 13–15). This also dispenses with the need for a second surgical intervention (uncovering).
Prosthetic procedure
The base of the temporary prosthetic restoration, which should be supported occlusally (fig 15), must not touch the healing caps statically and functionally during initial healing. This can be checked with a silicone paste (Fit Checker).
Five months post implantation, the biological width has become perfectly established in the healthy mouth (see comparison figs 13 and 16). Using a screw-retained, open implant impression (fig 17), it was possible to fabricate the four-unit CMC bridge 32xx42 with great precision (fig 18), which allowed an adequate outcome in terms of hygiene, chewing comfort, aesthetics and phonetics (fig 19). Here it is recommended to communicate the exact dimensions of the individually determined approximal space brushes (fig 19), which are to be tested in vivo on the patient and re-evaluated during try-in (gingiva resilience vs. plaster cast).
Final outcome
The one-year long-term follow-up showed stable and healthy hard and soft tissue conditions in line with established biological principles for soft tissue level implants (figs 20–22). The probing measurements were all at ≤3mm with negative BOP bleeding values (bleeding-on-probing) as well as a broad band of attached periimplant gingiva. Surprisingly, the implant mobility values (PTV periotest values) were significantly lower (reduced mobility), than known from the Straumann Narrow Neck implants to date, which may be due to the harder implant alloy (Roxolid) and/ or better hard tissue integration of the hydrophilic SLActive surface.
Conclusion
Narrow Neck CrossFit implants extend the indication field, particularly in very narrow spatial conditions. As soft tissue level implants they provide perfect aesthetics, while at the same time offering good preservation of the periimplant hard and soft tissue architecture.