EDI - European Association of Dental Implantologists

64 EDI
Case Studies
Anterior maxilla reconstructed with autogenous calvarial bone block grafts
restored with dental implants placed in a flapless image-guided procedure and
immediately loaded with a prefabricated prosthesis – a case report
The Key to Success
Dr Guido Schiroli, MD, DDS, Genoa/Italy, Dr Alessandro Acocella, DDS, and Dr Giuseppe Spinelli,
MD, Florence/Italy
This study describes the use of image-guided implantological procedures in a complex case involving the rehabilitation of the
anterior maxilla. Trauma to the teeth and alveolar process in the maxillary anterior region may cause severe bone deficiencies,
resulting in ridge atrophy and maxillary retrognathism with loss of upper-lip support and undesirable changes of the interarch
space, occlusal plane or interarch relationship.
After bone augmentation with autogenous bone blocks harvested from the cranium, endosseous implants were immediately
loaded with a prefabricated splinted bridge using a flapless approach and image-guided surgery. The calvarial area provides
primary stability thanks to a cortical grafting procedure well suited for treating localized alveolar-ridge deficiencies, resulting
in a very low resorption rate and highly dense structure. Image-guided surgery is optimal for determining the correct implant
position and performing a safe flapless procedure. A pre-fabricated prosthesis using the Nobel Guide protocol was placed at
the time of surgery for immediate loading and splinting of the implants at the previously grafted site. After a standard
healing period, zirconia abutments were connected to the implants, which were then restored with metal-free aesthetic
single-tooth crowns.
Injury to the alveolar ridge of the anterior maxilla
often causes severe deficiencies in the horizontal and
vertical dimensions, leaving inadequate alveolar
bone volume for standard treatment with osseointegrated
implants. In addition, the lack of supporting
bone may cause changes in the inter-arch space,
occlusal plane and arch relationship, accompanied by
maxillary retrognathism and a loss of upper-lip support.
An adequate bone supply is a prerequisite for
good aesthetic and biomechanical results, especially
in the anterior maxilla. The reconstruction and augmentation
of severely resorbed maxillary alveolar
ridges for subsequent implant placement have
become predictable procedures today, with different
grafting materials and techniques being available
[1-12]. The combination of autogenous bone grafts
with osseointegrated implants to repair larger
defects requires bone material from extraoral donor
sites such as iliac crest or the calvarium [13-24]. Split
calvarial block grafts have shown very low resorption
rates, fast revascularization and good long-term
results [20-24]. Many authors suggest delaying the
insertion of implants for three to six months after
the augmentation procedure and to wait an addi-
tional three to six months before applying functional
load [22-24].
Submerged healing, a waiting period of three to six
months before applying a functional load and a surgical
re-entry procedure were long considered a prerequisite
for osseointegration according to the Brånemark
protocol [25]. There were reports that early loading
associated with macromovements induced the
formation of fibrous tissue between the implant surface
and the bone [26-30]. However, several studies
were carried out involving immediately loaded
implants in animals and in humans, attesting to the
viability of immediate loading with survival rates similar
to those for implants with delayed loading [31-52].
More recently, there have been reports that there is a
continuum of implant micromovements ranging
from safe to unsafe and that the threshold of unsafe
movements may be between 50 and 150 μm [53-55].
Micromovement below that threshold may be tolerated
by the bone/implant interface, whereas exceeding
the threshold may result in fibrous encapsulation
of the implants [53-55]. Good bone quality, primary
stability and rigid splinting of the fixtures seem to be
the key to success for immediate-loading protocols.