Major bone augmentations: Proper flap and suture techniques are key to success
Dental implant therapy is a well-documented and well-supported procedure with high predictability,1 particularly if hard tissue is optimal. But in cases with insufficient bone volume, a bone augmentation procedure is required. Many techniques have proved to be effective for horizontal and vertical hard tissue augmentation, such as Guided Bone Regeneration (GBR) or autogenous bone block graft.2–4
Reducing flap tension
Independent from the bone augmentation itself, primary wound healing appears crucial for a positive outcome. Unfortunately, complications associated with these procedures are not irrelevant. Studies report complication rates of 45% with vertical GBR3 or 29.8% with vertical block grafts.4 Flap tension for primary wound closure of mucoperiostal flaps seems to the most important factor.5 Minimal flap tension (lower than 5 gr) is associated with 100% primary wound closure, while increasing the flap tension increases the incidence of wound dehiscence. This means that soft tissue release is a crucial step in bone augmentation surgery. Clinically, three types of flaps can be released by periostal incisions and coronal advancement – these are the lingual and vestibular flaps in the mandible, and the vestibular flap in the maxilla.
Three types of released and advanced flaps
The mandibular lingual flap is released by interrupting the thin periosteum layer with an elevator or dissector. The use of a blade may be avoided or limited to the mesial area of the mandible, where the periosteum is thicker.6 In the distal area the more superficial fibers of the mylohyoid muscle may be denuded simply by elevating a full thickness flap, since the mylohyoid line is in a more cranial position. In some cases, detaching muscle fibers from the internal face of the flap may increase the coronal advancement of the flap.7
The mandibular vestibular flap is released with a scalpel blade (15c). The tip of the blade should contact the superficial inner face of the flap starting from the vertical releasing incision and moving distally or mesially . The blade works with the cutting face upside down and the non-cutting area facing the flap. Once the periosteum is interrupted, the flap can be elongated with an elevator or dissector, avoiding vascular damage. It is important to work where the flap reaches the fornix, so as not to weaken the flap itself. Consider the position of the mental foramina and the mental nerve, maintaining a safe distance of six mm from these anatomical structures.
The maxillary vestibular flap is released in a manner similar to the mandibular vestibular flap, except that usually, once the periosteum is interrupted, the flap is elongated with a blade (instead of elevator or dissector) because the density of elastic muscle fibers inhibits coronal advancement.
Continue reading this article and review surgical images at the Regeneration Expert Blog here.