As part of a new study concept, 40 one-piece ceramic implants (Straumann® PURE Ceramic Implant, CIM) were placed in 33 patients and followed up over a period of two years5. The patients in this group were not specifically preselected and were referred by various general dentists. The patients were pretreated and prosthetically managed by the referring colleagues. A ceramic implant was selected either in response to the patient's request for a metal-free restoration or for esthetic reasons. After the patients gave their informed consent, their cases were documented by case report forms, x-rays and photographs. Four implants were placed in the anterior teeth and 36 in the premolar and molar areas. In addition to cases with an adequate bone stock, some implants were inserted in a compromised bone situation: in the maxillary molar area with a simultaneous or two-stage external sinus lift where the vertical bone stock was inadequate. Simultaneous lateral augmentations in the anterior teeth area were also performed using the guided bone regeneration (GBR) technique. After a corresponding healing period, the implant shoulder was exposed, and the referring prosthetist assumed responsibility for the prosthetic provision. The patients were then asked to return for further check-ups. After a one-year observation period, the survival and success rates for 25 patients (30 implants) who attended their follow-up appointments were 100 percent. No implant loss occurred during this period, and all implants could be fitted with prosthetic restorations.

First published in Implantologie Journal 7/8 2017.

CASE REPORT 1

Initial situation

The 47-year-old woman was referred for a consultation. The patient had no pre-existing illnesses and she was a non-smoker. There was no evidence of parafunctional habits. On the panoramic x-ray, teeth 36, 46 and 47 showed apical foci. The patient complained of occasional pain. She was briefed comprehensively about the possible treatments, including the option of implants. She specifically requested a completely metal-free restoration. Teeth 36, 46 and 47 were not worth preserving and were subsequently removed without complications.

Treatment planning

The subsequent implant planning took place two months after the removal of these teeth. Digital volume tomography (DVT) visualized the ideal implant position in three dimensions. Since the patient had meanwhile finally decided on a ceramic implant, the exact positioning of the implants was extremely important. For reasons of cost, the patient decided not to have an implant in area 47. Four months after teeth removal, ceramic implants were placed in areas 36 and 46 under local anesthesia.

Surgical procedure

An incision was made in the alveolar ridge, but vertical releasing incisions were waived since the ridge was wide. Initial drilling of the cortical bone with the round bur was followed by drilling of the first pilot hole (Bone Level range, Straumann®) to a depth of 10 mm, as previously determined during the DVT planning. The correct prosthetic position was checked using a position indicator (2.2 mm), a crucially important step for a one-piece implant. The correct assembled height of the implant can also be determined using the position indicator. Assembled heights of 4 and 5.5 mm are available. Drilling of the pilot hole (Ø 2.8 mm) was followed by the definitive preparation using a twist drill (Ø 3.5 mm). A corresponding position indicator was again used here. The profile hole was drilled with the profile drill (Ø 4.1 mm). Since type I bone was present at both implantation sites, threads also had to be tapped. The implants were inserted, using the right-angled handpiece, in areas 36 (Straumann® PURE Ceramic, Ø 4.1 mm, length 10 mm, assembled height 5.5 mm) and 46 (Ø 4.1 mm, length 10 mm, assembled height 4 mm). Both implants were primarily stable. The wound was closed with a monofilament 5/0 suture. A postoperative control x-ray was recorded. When the sutures were removed a week later, the wound appeared to have healed normally. The patient only returned five months after the implantation for exposure, although a three-month healing phase had been planned. The implants were properly integrated in the bone.

The patient's subjective impression that the peri-implant gingiva was particularly free of inflammation and lay tight against the implant was also confirmed. Rapid soft tissue healing was also observed during the first few postoperative weeks. The implant was exposed with the laser (erbium-YAG): since the gingiva had shrunk around the implant the full circle of the implant shoulder was visible. Only now was the plastic protective cap also applied in order to create the optimal conditions for the impression taking. For hygienic reasons, the protective cap had not been applied initially after the implantation since substantial odor build-up was observed here after it was worn for a prolonged period. The patient was subsequently referred back to the prosthetist for further management.

Result

The most recent clinical and radiological follow-up appointment occurred 13 months after implantation. The clinical situation was normal and the patient was very satisfied. X-rays showed a slight vertical bone loss mesially at implant 36, although no bleeding occurred on probing. It is possible that the implant had been placed slightly too deeply in this area, restoring the "biologic width" in relation to the implant shoulder. The recommendation is that the implant shoulder should sit 1.8 mm above the crestal bone. 

CASE REPORT 2

Initial situation

A 36-year-old non-smoking woman in good general health presented with a tooth gap in the region of 25/26 for implant counselling. The patient stated that these teeth had been removed several months previously by her dentist due to chronic inflammation. Clinical examination revealed a non-inflamed, fully healed mucosal situation. The patient had no clinical symptoms. Digital volume tomograms of the upper and lower jaws were prepared to assess the vertical and horizontal bone stock and the sinus cavity. In the gap area the x-rays showed a vertical bone supply that was reduced to a minimum of 5.8 mm, while the horizontal bone stock appeared sufficiently wide, at 8 mm. An area of chronic apical periodontitis measuring 5 mm in diameter was also apparent around the adjacent tooth 24, while a maxillary sinus septum was observed in the region of 26.

Treatment planning

The patient was informed about various treatment options during the briefing process. The patient opted for metal-free ceramic implants. In view of the reduced vertical bone stock in the region of 26 and the chronic apical periodontitis at tooth 24, a sinus lift and apicoectomy in the same session were planned in order to minimize the surgical workload. The implants were positioned virtually using a 3D-planning system (Galileos Implant). Two ZrO₂ implants (Straumann® PURE Ceramic Monotype implants Ø 4.1 mm RD, ZLA 12 mm, AH 4 mm) were planned.

Surgical procedure

Under local anesthesia (Ultracain Dental forte), an incision was made in the alveolar ridge at 25/26 with a circular incision around the gingival margin of 24 and 27, followed by a releasing incision distal to 23. A mucoperiosteal flap was raised to expose a sufficient operative field. The apicoectomy of tooth 24 was now performed with retrograde root filling. A cortical window in the area of the facial maxillary sinus wall was then created in the classical manner using a diamond-coated tip. The preserved, intact maxillary sinus mucosa was sufficiently dissected in the mesial, distal and cranial directions. The maxillary sinus septum previously observed on the DVT was successfully included in the dissection without any rupturing of the sinus mucosa. In accordance with the virtual planning and the three rules (minimum distance of 1.5 mm between the adjacent tooth and implant at bone level, minimum distance of 3 mm between adjacent implant shoulders at bone level and optimal orofacial positioning of the ceramic implant), the position of the implants was determined and fixed using a round bur (Ø 1.4 mm). The implant axis was then determined with the 2.2 mm pilot drill. The one-piece implant position indicator was inserted in order to check the implant position, angulation and restorability (assembled height, distance to opposing tooth). This was an absolutely essential step in view of the required exact positioning of the one-piece implant. Any positional corrections might then be made with the next drilling step. Using the pilot drill (Ø 2.8 mm), the implant bed was widened. As with the first drilling step, the drill tip naturally appeared in the externally created cavity of the sinus lift. Consequent perforation of the sinus mucosa here must be avoided at all costs. The implant position indicator (Ø 2.8 mm) was now used again to check the implant position, angulation and restorability. Continuing with the twist drill (Ø 3.5 mm), the implant bed was widened, accompanied by further checking with the position indicator. Finally, the profile drill was used to ensure that no excessive force was being exerted on the implant or implant bed during implant insertion. On completion of the drilling process for both implants, a resorbable membrane was inserted to support the clinically thin maxillary sinus mucosa. The created cavity was filled with bovine hydroxyapatite. The two ZrO₂ implants (Straumann® PURE Ceramic Monotype implants, Ø 4.1 mm RD, ZLA 12 mm, AH 4 mm) were then inserted mechanically using the transfer piece. A primary stability of over 35 Ncm was achieved for both implants. The positioning was checked and the wound closed with monofilament sutures.

Result

Two weeks after the operation, the mucosa around the implant had healed normally. Eight months postoperatively, the implants had integrated in the bone without any inflammation. The patient, fitted with ceramic crowns, returned 13 months after the operation for follow-up. Clinical and radiological controls showed normal findings. Subjectively, the patient was very satisfied with the restoration.

Conclusion for practice

Although titanium implants have proved themselves over recent decades, patients are increasingly requesting alternative metal-free materials. With the implant system described in this article, the dentist now has a natural-looking treatment option with high fatigue strength. The macro- and micro-roughness of the ZLA surface appears to play an important role here and is similar to the topography of the SLA® surface. In preclinical studies the ZLA surface showed osseointegration corresponding to that seen for the Ti-SLA surface in terms of peri-implant bone density and the BIC value (bone-to-implant contact)⁶. As regards the healing process of the soft tissue around zirconium dioxide implants, further research is still needed. Since the preliminary results for the long-term stability of zirconium dioxide implants basically appear very promising, they can be assumed to show similar values to those of titanium implants. Moreover, the latest scientific findings indicate that the accumulation of the bacterial biofilm on ceramic is lower than on titanium implants, which may explain why clinical follow-up studies have not found any cases of peri-implantitis around ceramic implants⁷. In future, the material zirconium dioxide can certainly become an established alternative to titanium although, as the situation currently stands, it will complement, rather than replace, the titanium implant and allow dentists to expand their own range of treatments.

Implantologie Journal 7+8/17, OEMUS MEDIA AG, Leipzig, Germany 2017