To achieve optimal functional and aesthetic results after implant installation in the anterior maxilla, correct implant positioning and establishment of an optimum volume of hard- and soft-tissues are crucial . After tooth extraction, the socket walls collapse. In a horizontal direction, the reduction of the alveolar socket (3.79 ± 0.23 mm) is higher than vertically (1.24 ± 0.11 mm) at 6 months . As a consequence, the oral mucosa retracts, thereby compromising aesthetics.

Current consensus is that immediate implant placement (IIP) itself does not prevent reported horizontal and vertical resorption of the buccal crest . Applying bone substitutes is reported to be effective in limiting both horizontal and vertical ridge alterations. As a barrier material, they preserve the ridge volume in a maximal way . Obviously, these measures should also be performed during IIP . Even during bone augmentation procedures, the role of bone substitutes as barriers and stabilizers is indisputable .

Compared with the conventional approach, in which the socket is allowed to collapse over a 6- to 12-week period before implant installation, IIP allows immediate restoration, is less invasive and more cost effective, resulting in reduced overall treatment time and higher patient comfort. However, IIP is often associated with buccal bone loss and midfacial recession . New insights advocate installing the implant in a more palatal position, as crestal bone resorption and midfacial soft-tissue recession are correlated with an implant placed too close to the buccal crest . Creating a buccal gap of at least 2 mm results in new bone formation, coronal to the receding buccal bone wall . Also, the thickness of the buccal crest itself plays an important role: the thinner it is, the more resorption occurs . To create a gap of at least 2 mm, the use of implants with a smaller diameter is advocated. As radiographic data that give insight into the process of buccal bone remodelling after IIP are still lacking , the aim of this retrospective study was to analyse the fate of the buccal crest and the aesthetic outcome following IIP.

IIP Protocol

In cases of an empty socket immediately after avulsion, or if the failing tooth was still in situ, a CBCT scan (Scanora, Soredex, Tuusula, Finland) with a standard dose, 85 kV, 15 mA, and a small field of view (FOV) of 6 cm by 6 cm was made, to decide if IIP was feasible ( Fig. 1 A). An absolute prerequisite for IIP was the presence of sufficient palatal bone volume: (1) to offer the implant sufficient primary stability to allow immediate restoration; and (2) to create a minimum of 2 mm distance between the buccal implant contour and the inner buccal crest. Patients were instructed to take 2 g of amoxicillin 1 hour preoperative followed by 500 mg amoxicillin every 8 hours during 5 days postoperatively and to rinse with 0.12% chlorhexidine solution twice a day during 14 days post surgery. In addition, intact interdental septa and buccal crest had to be present. After atraumatic extraction, the socket was cleaned extensively using a bone excavator to remove remnants of the periodontal ligament and/or inflammation tissue and to promote bleeding. The keratinized gingiva remained intact as no flaps were raised. Then, the osteotomy was directed palato-apically in relation to the original apex. The drill protocol used was in accordance with the manufacturer’s guidelines for NobelActive Internal implants (Nobel Biocare, Washington DC, USA). Before applying bone substitute with grain size 0.25–1.0 mm (Bio-Oss, Geistlich Pharma AG, Wolhusen, Switzerland), the last used drill was placed into the osteotomy in order to prevent congestion of the implant bed with bone substitute. After packing the granules, the drill was removed, creating a tunnel, through which the implant was installed (NobelActive™ Internal; Nobel Biocare, Washington DC, USA). The implant seat was positioned 3 mm deeper than the buccal gingival margin. Immediately after this flapless surgery a second small FOV, low-dose CBCT scan was made to evaluate the implant position ( Fig. 1 B). In case of inaccuracies in this stage corrections still could be made. Hereafter, a titanium temporary abutment (Nobel Biocare, Washington DC, USA) was positioned onto the implant that allowed the fabrication of a screw-retained temporary crown (Protemp, 3 M ESPE Dental Products, Delft, The Netherlands) under cofferdam. Six months later, either an individualized, screw-retained, zirconium-porcelain crown, or an individualized zirconium abutment (Procera, Nobel Biocare, Washington DC, USA) with a cemented porcelain facing, was placed. To evaluate the height and thickness of the buccal crest in time ( Fig. 1 C), also a late postoperative small FOV, low-dose CBCT scan was executed.

(A) CBCT: the preoperative cross-section shows a root after apicoectomy; a thin buccal crest is still present. (B) CBCT: immediately postoperative cross-section; a clear, thickened, buccal bone crest can be observed. (C) CBCT: late postoperative cross-section; hard-tissue remodelling was performed at the buccal crest after incorporation of the bone substitute material.