#Full-Arch 16. Apr 2020

Immediate fixed rehabilitation of a resorbed mandible in a medically compromised patient

A clinical case report by Inge De Latte, Belgium

Patients in need of extensive implant-retained rehabilitation appreciate receiving a near-term fixed temporary prosthesis. This report describes the clinical and lab procedures for an immediate mandibular full-arch denture. It is screw-retained on four Straumann® BLX implants utilizing the Straumann® Pro Arch concept.

In a medically compromised 67-year-old male patient, the remaining hopeless teeth are extracted and four interforaminal implants immediately inserted. As there is only limited posterior bone available the posterior implants have to be tilted.

Due to the specific features of the Straumann® BLX implants, the temporary fixed prosthesis can be successfully loaded on the day of surgery. The patient is happy to regain his functional competence, allowing him to chew, speak and laugh during the osseointegration period.

Initial Situation

A 67-year-old male patient presents at the surgical clinic with a reduced number of teeth in both jaws (Figs 1-4). All teeth are discoloured and several have root fillings, restorations and secondary caries. There is also a generalized loss of periodontal attachment, combined with gingival recession and wedge-shaped cervical defects caused by tooth brushing in the maxilla. Medically, he suffers from hypertension and type-2 diabetes mellitus, with both conditions under internist control.

As a preliminary treatment by the referring dentist, tooth #33 had to be extracted due to an endo-periodontal lesion (Fig. 1). Tooth #44 has secondary caries, periodontal pockets with bleeding on probing, grade 3 mobility and is assessed as hopeless. Teeth #34 and #35 also show reduced periodontal support, and grade 2 mobility. The patient agrees to have all remaining mandibular teeth removed in favour of a purely implant-retained prosthesis.

In regard of the planned implant therapy the radiographic assessment (Fig. 1) and clinical examination (Figs. 2-4) reveal severe vertical and horizontal alveolar bone resorption in the posterior maxilla. In the mandible there is a moderate vertical resorption, with narrow ridges in the edentulous areas and a lack of vestibular fornix depth, especially in the interforaminal region.

The patient wears removable tooth-supported partial dentures, with a cast frame in the maxilla (Figs. 5-6). The vertical intermaxillary dimension is reduced (Fig. 4), and both dentures are unstable, preventing the patient from eating or speaking well, which is his chief complaint.

As a cause-related treatment before the onset of implant therapy, the patient receives a professional tooth cleaning, careful oral health instructions, and initial periodontal debridement.

Treatment planning

Based on the patient’s cone beam computed tomography (CBCT) data, the interforaminal implant positions are planned using the coDiagnostiX® software (Fig. 7). The 3D planning file will be used as an orientation aid, while the preparation of the implant beds and insertion of the implants will be performed with a Straumann® Pro Arch Guide.

Surgical procedure

A.   Flap preparation and extractions

Bilateral mental and lingual block injections, and additional vestibular infiltrations, are performed to anaesthetize the hard and soft tissues in the interforaminal area. Crestal and intrasulcular incisions are made with a scalpel to allow dental extractions and minimal-invasive exposure of the surgical field (Fig. 8). Teeth #35, #34 and #44 are carefully removed (Figs. 9-10).

B.   Implant site preparation and alignment

First, the midline osteotomy is prepared using a ∅ 2.2 mm Pilot Drill to a depth of 10 mm. The Straumann® Pro Arch Guide is then shaped to match the dental arch and placed in the midline osteotomy (Fig. 11). In order to reduce bleeding and possible morbidity in the medically compromised patient, the flap is raised only partially.

The osteotomies are prepared and four Straumann® BLX ∅ RB 4.5 mm Roxolid® SLActive® 12 mm placed at a maximum minimum torque of 35 Ncm, and according to the surgical protocol for medium quality bone. The specific instrument sequence for this implant type and the patient’s bone quality is indicated on the Straumann® Modular Cassette.

To achieve an exact angulation and alignment of the implants the Straumann® Pro Arch Guide is used together with Alignment Pins and Depth Gauges. The initial and the last preparation steps for the posterior implants are shown in Figs. 12-14. Using the 3D software planning as guidance, the positions and alignment of the implants have been defined in respect of the prosthetic design planned and the anatomic conditions, which is shown in Figs. 15 and 16.

Because of the inflammatory areas at the position or former tooth #33 and the resulting bone deficiency, the implant positions of the two central implants have to be adapted accordingly (cf. Figs 15 and 36).

Following implant insertion (Figs. 17-18), the dedicated Straumann® Bone Profiler is used to prepare the bone coronally to the implant shoulder. This step is helpful in cases where the bone inter­feres with the abutment’s emergence profile (Fig. 19). The following Screw-retained Abutments are placed at a torque of 35 Ncm (Figs. 20-21):

  • Anterior: RB/WB straight, angle 0°, ∅ 4.6 mm, gingiva height 2.5 mm
  • Posterior: RB/WB angle 30, ∅ 4.6 mm, gingiva height 3.5 mm

C.   Tissue management and impression taking

As a guided tissue regenerative measure, Straumann® XenoGraft is placed around the implants and the material protected with a collagen membrane (Fig. 22-23). As an optional step, to make augmentation and suturing easier, Protective Caps ∅ 4.6 mm have previously been placed on the Screw-retained Abutments. For an improved wound healing Straumann® Emdogain is applied prior to flap closure (Figs. 24-25).

Next, the Protective Caps are removed, and the dedicated Impression Posts and Caps placed (Fig. 26). The clinical situation is transferred into the laboratory on abutment level, using the closed-tray technique and polyether impression material (Figs. 27-28). The Protective Caps are repositioned and Straumann® Emdogain is again applied on top of the flaps. The patient is then allowed to rest during the fabrication of the temporary prosthesis.

Laboratory procedure

For the preparation of the master model the dedicated Implant Analogs are screwed onto the impression posts. To allow a check of the correct fit of the temporary prosthesis a gingiva mask is included (Fig. 29). The stone gypsum is poured to prepare the model, which is mounted into the articulator with the aid of the occlusal bite registration performed after the impression procedure (Figs. 30).

The technician fabricates the prosthesis using stock acrylic teeth (Fig. 31). For retention of the prosthesis on the implants Titanium Copings are screwed onto the Implant Analogs and their height is adjusted (Fig. 32). Using a silicone key the technician casts the temporary prosthesis, which is functionally adjusted and finalized using dedicated rotary instruments (Figs. 33-34).

Treatment outcome

The prosthesis is delivered to the patient and screwed onto the abutments on the same day (Fig. 35). The panoramic tomography shows an optimal positioning of the implants and gap-free retention of the Screw-retained Abutments and Titanium Copings, which demonstrate a close to parallel alignment (Fig. 36).

The patient is happy to receive an immediate fixed restoration, allowing him to get used to the new situation with “own teeth”. For undisturbed osseointegration he is advised to stick to a soft diet during approximately 2 months after implant placement. The patient receives thorough oral hygiene instructions and is scheduled for regular check-ups.

After final restoration of the mandible, which is combined with an increase of the vertical dimension, the maxilla is planned to be restored in a second step, in connection with two posterior implants.

Testimonial Dr. Inge De Latte

“We recently performed an exciting series of Pro Arch imme­diate loading cases (total of 40 implants) with the BLX implants. Even in cases involving difficult extractions, atrophic jaws, or patients with poor bone quality, we were able to load all implants.

Due to its surface and shape, the BLX implant can transform a difficult case into an easy one. The implants are very well suited for the combination of immediate extraction sockets with immediate implant placement. In and around the extraction socket, they create a stable, functional implant environment that enables immediate loading.

The soft tissue can easily and rapidly grow around the implant surface, while maintaining the natural papilla and garland shape of the gingiva.”  

Peer-reviewed article in EDI 2020/1