Straumann® Bone Level Tapered Implant Ø 2.9 mm

Use of the Straumann® Bone Level Tapered Implant Ø 2.9 mm in the esthetic zone

A clinical case report by Stefan Hicklin, Jelena Gavric, Vincent Fehmer, and Irena Sailer, Switzerland

Author: Stefan Paul Hicklin

Dr. med. dent. Stefan Paul Hicklin

Studies in Switzerland at the University of Zürich and graduation in 2002. From 2005-2008 post-graduate student at the Clinic for Fixed and Removable Prosthodontics and Material Science (University of Zürich, Chair: Prof. C.H.F. Hämmerle). 2009-2014 Senior Lecturer at the University of Bern at the Department of Reconstructive Dentistry (Chair: Prof. U. Brägger). Since end of 2014 Senior Lecturer at the Division of Fixed Prosthodontics and Biomaterials, University Clinics of Dental Medicine, University of Geneva (Chair: Prof. I. Sailer). Specialist for Reconstructive Dentistry (SSRD).

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Initial situation

A 51-year-old female patient presented herself at the University Clinics of Dental Medicine in Geneva (Division of Fixed Prosthodontics and Biomaterials) in April 2016 complaining of occasional episodes of mild pain in the region of tooth 12. The patient was healthy, a non-smoker and was not taking any medication. During the clinical examination, she complained of mild pain on percussion of tooth 12. The tooth was endodontically treated and restored with a composite build-up (Figs. 1-3). Furthermore, the tooth showed increased grade 2 mobility, and no periodontal probing depth (PPD) exceeded 4mm. The periapical radiograph showed radiolucency around the apex of tooth 12 (Fig. 4).

Treatment planning

After consultation with an endodontic specialist, it was decided to extract tooth 12 and to perform a ridge preservation procedure to maintain the volume. After a healing period of 8 weeks, an early implant placement procedure was planned. A resin-bonded fixed dental prosthesis was also discussed as an alternative treatment option. Since the distance between teeth 11 and 13 was narrow (approximately 6mm), the treatment plan was to place a Straumann® BLT implant with a diameter of 2.9mm (Small CrossFit® connection), including guided bone regeneration if needed. After successful osseointegration and a provisional phase, the implant was planned to be restored with a translucent zirconia (Katana Zirconia, STML A2 T18) crown on a titanium bonding base (Straumann® Variobase®). The plan was to take an analog impression and then follow a digital laboratory workflow using CAD/CAM technology.

Surgical procedure

The tooth was extracted and a xenogenic bone substitute in combination with a punch graft from the palate was used to perform a ridge preservation procedure (Figs. 5, 6). A provisional removable prosthesis was adapted and incorporated to replace the missing tooth.

Six weeks later, a well-maintained ridge with completely healed soft tissue conditions was observed clinically (Figs. 7, 8). Alginate impressions of the situation were made, and a wax-up of tooth 12 was fabricated on the plaster model. Based on the wax-up, the dental technician manufactured a conventional surgical guide (Figs. 9, 10).

On the day of implant placement (seven weeks after extraction), the patient was pre-medicated with 1500mg amoxicillin and 600mg ibuprofen. Under local anesthesia, a crestal incision from the palatal line angle of tooth 11 to the palatal line angle of tooth 13 and a vertical releasing incision distal to tooth 13 were performed. A full-thickness flap was elevated (Figs. 11, 12). The conventional surgical stent was placed, and the implant bed was prepared according to the manufacturer’s instructions as follows: At the beginning, the implant position was marked with a 1.4mm round bur. The first osteotomy was performed with the 1.6mm diameter needle drill (Figs. 13, 14).Next, the implant bed was prepared with the 2.2mm diameter pilot drill. The correct axis and the vertical position were checked with the help of the specific indicators and the surgical guide (Figs. 15, 16). As the bone was quite soft, there was no need to use the profile drill and the tap. A Straumann® BLT Small CrossFit® (SC) implant (Roxolid®, SLActive®) with a diameter of 2.9mm and length of 12mm was placed with good primary stability and a correct prosthetic position / axis (Figs. 17, 18). A small closure screw was applied to cover the implant. Autologous bone chips, a xenograft and a collagen membrane were used to augment the buccal fenestration defect and enhance the vestibular ridge contour for a more natural appearance of the final crown. The periosteum was released, and the flap was repositioned to achieve primary wound closure with a 5.0 ePTFE non-absorbable monofilament suture (Figs. 19, 20). Antibiotics (amoxicillin 3 x 750mg for 5 days), painkillers (600mg ibuprofen as needed) and chlorhexidine mouth rinse (0.2%) were prescribed. The sutures were removed 10 days after implant placement.

The healing period was uneventful, and 3 months after surgery the clinical examination revealed healthy tissues (Fig. 21). At this time, the abutment connection was performed under local anesthesia with a buccally rotated U-shaped mini-roll flap. The soft tissue covering the implant was deepithelialized using a round diamond bur. A U-shaped incision was performed, and the flap over the implant was raised. A small tissue pouch was prepared at the buccal aspect of the implant, and the flap was rotated into it. After removal of the closure screw, a healing abutment with a gingival height of 3.5mm was inserted (Fig. 22).

Prosthetic procedure

Two weeks after the abutment connection, an analog impression was taken. In the laboratory, the dental technician produced the provisional crown using the temporary abutment made of a titanium alloy (TAN) and resin composite (Fig. 23). The provisional crown had a kind of ridge lap design to avoid excessive pressure on the soft tissue during insertion. After removal of the healing abutment, healthy peri-implant mucosa was found to be present (Fig. 24). The provisional crown was inserted and tightened to 15Ncm (Fig. 25). During the following weeks, the provisional crown was modified twice with resin composite to optimize the emergence profile. It was also used to apply pressure to tooth 11 because the patient wished to close the diastema.

After a provisional phase of three months, a second impression was taken with an individualized impression coping. The master cast was produced, and the Variobase® abutment (gingival height of 1mm) was screwed to the implant analog. The titanium bonding base was scanned using the Dental Wings 7Series scanner. The implant crown with a buccal cutback was designed with the Dental Wings Open Software (DWOS) and milled with the Wieland Zenotec Select CAM machine (Fig. 26). A high-translucency zirconia was the chosen reconstructive material (Katana STML A2 T18). Following the sintering process, the crown was stained and veneered on the buccal aspect with hand-layered ceramic (Fig. 27). After one bisque stage try-in, the crown was finalized, cemented onto the titanium abutment and polished (Fig. 28).

Final result

The final crown was inserted without any problems, and the clinical fit was verified with a peri-apical radiograph (Fig. 29). The reconstruction integrated nicely in the existing dentition, and the patient was very happy with the outcome (Fig. 30). The crown on implant 12 now appeared to be a bit wider than the natural tooth 22, but the patient thought that it was more important to close the diastema (Fig. 31). It was also decided to place the crown a bit more towards the buccal aspect than tooth 22. Even directly after insertion of the final reconstruction, the mucosal situation was more than acceptable. Nevertheless, further improvement over the next few weeks or months can be expected. The buccal volume was preserved well over time and can be compared with the situation for tooth 22 (Fig. 32).

The final closure of the screw access hole will take place three to four weeks after insertion, with PTFE tape and resin composite. The recall interval will be set at 6 months.