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Horizontal augmentation

How to use bone blocks

05.04.2015
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Surgeons can avoid complications with autogenous bone blocks if they use adequate incision techniques, rigidly fix the block and cover it with a suitable granulate bone substitute and membrane.

Prof. Carlo Maiorana | Italy

After tooth extraction the alveolar ridge undergoes a physiological resorption leading to narrowing. In the esthetic area and for specific indications, such as lateral upper incisor agenesis or absence of lower incisors, the use of narrow diameter implants is considered a first choice option.1 But on a routine basis, a residual ridge width of at least 5 mm has to be present to allow the placement of a standard diameter implant (Ø 3.8 mm). In posterior areas clinicians should choose wider implants for prosthetic reasons, therefore, the lack of an ideal width is more frequent.


Autogenous bone blocks

One proven technique for optimizing the horizontal ridge is autogenous block grafts. The main advantages of autogenous blocks are their osteoconductive, osteoinductive and osteoproliferative properties. However, since the amount of bone is limited, this technique is not suitable for large defects and complete maxillary reconstructions.


The Clinical tips: flap technique

The coronally advanced flap is preferred when dealing with thin mucosal tissue (thin biotype), since the preparation of a tunnel is likely to cause perforations or tearing of the gingiva. The coronally advanced flap is also recommended when a greater amount of coronal advancement is planned and if the scalloped nature of the free gingiva is absent – flatly contoured gingival zenith, such as in the lower anterior region.
The tunneling technique is ideal when working with a thick biotype, highly scalloped free gingiva and suitable keratinized tissue. The tunneling technique should also be considered if esthetics are critical and a mild to moderate coronal advancement is anticipated. One of the key factors for success is the proficiency of the periodontal surgeon.


Connective tissue graft vs. biomaterial

Connective tissue grafts help create keratinized gingiva, based on a study of tissue specificity by Karring and co-workers.3 In this epithelial differentiation study, Karring was able to demonstrate that free grafts harvested from the palate produced keratinized gingiva, whereas grafts transplanted from the non-keratinized alveolar mucosa produced alveolar mucosa.4

Advantages of connective tissue grafts include plasmatic circulation (capillary beds within the grafts) that help with high graft survival, outstanding color match after healing and dimensional stability. Disadvantages include patient morbidity, e.g. bleeding, delayed healing and pain, along with the secondary graft harvest sites. (Figs. 1, 2)

Accordingly, clinicians have been interested in developing a graft substitute. Such biomaterials not only avoid connective tissue graft harvest and associated morbidity but also provide unlimited supply with consistent quality. Working with such biomaterials, complete primary closure with a tension-free flap is recommended. Ideal biomaterials should act as scaffolding to promote ingrowth and regeneration by host cells, while remaining dimensionally stable. (Fig. 3)

Prof. Carlo Maiorana

Prof. Carlo Maiorana | Italy

Oral Surgery and Implant
Department University of Milan School of Dentistry
Fondazione IRCCS Policlinico Cà Granda

References
  1. Maiorana C, et al.: Clin Oral Implants Res 2014; 26: 77-82.
  2. Anderson L, et al.: Oral and maxillofacial surgery; UK, 2010; 385–390.
  3. Maiorana C, et al.: Bone augmentation procedures in the esthetic area with Bio-Oss and Bio-Gide; Italia Press Ed, Milan, 2009.
  4. Maiorana C, et al.: Int J Periodontics Restorative Dent 2005; 25: 19–25.
  5. Maiorana C, et al.: Open Dentistry J 2011; 25: 71-78.
  6. Herford AS, et al.: J Oral Implantology 2011; 37: 279–85.

Illustration Header: Alessandro Holler / Quaint

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