From practitioner to practitioner - ZZI 03/2013

Reconstruction of a severely atrophic maxilla by extensive augmentation and Guided Surgery

F. M. Maier1

Extensive augmentations enable the surgeon to build up the basis for fixed implant supported restorations even in cases with large bony defects due to periodontal disease. A less invasive alternative to grafting bone from the iliac crest involves augmentation with allogenic donor bone. The three-dimensional augmentation and implant planning based on CBCT data is an important aid in total reconstructions. Guided surgery allows not only a more gentle approach, but especially exact prosthetic positioning of the implants.

Keywords: severe periodontitis; large bone defects; sinus floor elevation; computer guided surgery; autologous bone grafts; conical implant-abutment-connection

Citation:

Maier FM: Reconstruction of a severely atrophic maxilla by extensive augmentation and Guided Surgery. Z Zahnärztl Implantol 2013;29:230–242

DOI 10.3238/ZZI.2013.0230–0242

Introduction

Periodontal diseases, in particular severe periodontal diseases, are a major challenge for implant prosthetic rehabilitation. Generally there are extensive bone defects due to inflammation processes. Periodontally damaged patients also have a higher risk of developing peri-implant inflammation [10, 1, 8, 9]. Grafting iliac crest bone is a proven treatment option in the case of large bone defects [2]. Augmentation using allogenic bone can also be considered as an alternative to grafting bone from the iliac crest. Low bone availability in the maxillary posterior region also makes sinus floor elevation necessary for creating an adequate implant site [7, 3]. A three-dimensional CT or CBCT analysis is an important instrument for the planning of bone augmentation and implant placement. Modern surgical stent systems facilitate transfer of the planned implant position intraorally [12].

 

Initial situation and pretreatment

In July 2010 a 65-year-old female patient presented wanting a second opinion from our practice. She complained about loose teeth in the upper jaw due to long-term periodontitis (Fig. 1). The patient could only eat soft food and held her hand in front of her mouth when speaking, as she felt ashamed. Her previous dentist had already explained about the deep-seated periodontitis 15 years ago and accused the patient of poor oral hygiene. This prompted the patient to clean the teeth intensively (Fig. 2). Periodontal treatment was not initiated. The final outcome was that all teeth had to be extracted and, apart from a full denture, no alternative treatment was presented. Implants were not considered due to the periodontal disease.

The main concern of the patient was the wish to have a fixed restoration in the upper jaw. The patient brought an orthopantomogram from the previous treating dentist (Fig. 3); teeth 27, 28 and 37 had already been extracted. At the initial consultation I advised the patient that the hopeless teeth 15–22, 25, 36, 32–42 should be removed and an immediate restoration should be fitted in the upper jaw, followed by systematic periodontal treatment and then three-dimensional evaluation of the tissue situation to clarify possible treatment alternatives. A fixed, long-term temporary restoration was recommended for the treatment of the lower jaw.

The teeth were extracted on 13 July 2010. Figure 4 shows the upper jaw two months after the teeth were extracted. CBCT analysis from 31 October 2010 confirmed the immense bone loss and enabled calculation of the bone volume to be augmented. The ridge width was adequate in the posterior region, however, the bone height was very low with 1–3 mm (Fig. 5).

 

Treatment alternatives

Following evaluation of the tissue situation, a check of the aesthetics, model analysis and functional analysis, two treatment alternatives for the upper jaw were proposed to the patient:

  • 1. Bilateral sinus floor elevation, vestibuloplasty for creating attached mucosa, implant placement in the 23 region and in the posterior region, treatment with a removable bridge, anchorage using prefabricated telescope crowns (SynCone-System, DENTSPLY Implants, Mannheim, Germany). This procedure enables compensation of the labial tissue defect and support of the lips by the acrylic base. A palate-free design provides high intraoral comfort for the patient and no functional restrictions compared with a fixed restoration.
  • 2. Additional augmentation labially using bone blocks. Due to the size of the defect it is necessary to graft iliac crest bone or alternatively to graft allogenic bone. Protection of the anterior augmentation material using temporary implants. Placement of eight implants in the 1, 3, 4 and 6 region. Treatment with a fixed bridge restoration. This type of restoration requires much more extensive surgical soft tissue intervention to achieve an acceptable aesthetic outcome.

 

A removable restoration was not an alternative for the patient; she also did not wish an iliac bone graft. She therefore decided on the version of grafting allogenic donor bone. We use corticocancellous blocks (Puros Allograft Block, Zimmer Dental GmbH, Freiburg, Germany) for reconstruction of the alveolar ridge with this procedure. The maxillary sinuses are augmented using a mixture of allogenic cancellous particles (Puros Allograft Spongiosa Partikel, Zimmer Dental GmbH, Freiburg) and synthetically manufactured hydroxylapatite (Nanobone, ARTOSS GmbH, Rostock, Germany). When using allogenic blocks it is important to ensure extensive rehydration of the blocks using saline solution by producing a vacuum in a correspondingly large single-use syringe. This extracts the air from the cancellous bone and rehydrates the bone (Fig. 6).

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