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If the bone width is partly or completely insufficient, without vertical bone loss in the esthetic region and a remaining vertical bone height of > 10 mm in the other regions, the following procedures are recommended:

In the case of a partly bony defect on the vestibular and or palatal/lingual bone wall by a remaining crestal bone width of > 6 mm, implants can be inserted in combination with bone grafting using local bone chips and bone cores collected during implant preparation, with or without the membrane technique.^37,49,92 However, the decision to use this technique is also strongly determined by the position of the smile line, which may require further grafting to adapt the gingival contour of the adjacent teeth and contour of the peri-implant soft tissue according to the overall esthetic situation.⁴³ The decision about whether implant placement should be performed simultaneously with grafting or after the consolidation of the graft depends on the morphology of the defect and whether the implant can be placed within the jaw contours (see Chapter 4). Bone spreading can play an important role in preserving and expanding the remaining bone by stretching the bone walls of the future implant site, augmenting the chance of implant insertion inside the bony contour.⁶² If these conditions are not met, it is recommended to first carry out the grafting, and then to insert the implant after 3 months.

In the case of an alveolar ridge width of 3 to 6 mm, the alveolar ridge can be augmented in the maxilla with extension plasty or bone splitting. This may be simultaneous or staged, depending on the stability of the vestibular mobilized bone wall. The decision to insert the implant simultaneously also depends on the possibility of inserting the implant inside the bony contours, but in addition, the implant direction must remain inside the tooth contour, which is not so easy with the bone splitting technique. For this reason, it is recommended to always combine bone splitting with a spreading of the palatal bone wall to enable the implant direction to be kept inside the tooth contour and to prevent later bone resorption and recession of the vestibular gingiva.

If the buccal bone wall becomes very mobile and thinner than 2 mm during this procedure, it is advisable to denude it from the periosteum and to stabilize the buccal wall with a bone block graft. This procedure is much more difficult in the mandible due to the cortical bone quality offering less elasticity for a greenstick fracture.

A ridge width narrower than 3 mm presents an indication for a two-stage procedure. In this situation, a bone block harvested mostly from the retromolar area of the mandible is grafted to the atrophied crest following the split bone block (SBB) technique (see Chapter 4) in order to achieve long-term predictable and stable osseointegration of the implants. The implants are usually inserted 3 months after the grafting procedure.