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rev port estomatol med dent cir maxilofac . 2019;60(4):175-188 181

Maxilla CCIV Option B – Placement of six implants with the same protocol
Anterior – advanced resorption: height >8 mm and <12 mm; as Option A for the anterior region of the maxilla. In the pos-
width >6 mm terior region, two pterygoid or tuberosity implants are placed
Posterior – severe resorption: height <4 mm or width <6 mm with an average angulation of 70.º to the occlusal plane. These
Advanced bone resorption is seen in the anterior region. The two implants are usually longer (15-20mm). They pass
bone height measured from the osteotomy level, with a >6- through the maxillary tuberosity, the pyramidal process of
mm crestal width, to the inferior border of the nasal cavity is the palatine bone and are fixed in a dense cortical bone of the
>8 mm and <12 mm. The posterior region is characterized by pterygoid process of the sphenoid bone (Figure 9).
severe bone resorption. The bone height measured from the Option C – Although there is less bone availability compared
alveolar ridge, with a <6-mm crestal width, to the inferior wall to Option C of Class III, the rehabilitation scheme is similar,
of the maxillary sinus is <4 mm. with four implants placed in the premaxilla to support an
overdenture.
therapeutic options
In this class, the severe posterior bone resorption (<4 mm) deciding factor
and the maxillary sinus extension prevent implant place- Option A includes a sinus lift, which reestablishes adequate
ment in the area without a sinus lift technique. Therefore, two posterior bone volume for implant placement and is a well-
surgical protocols are suggested for a fixed full-arch rehabili- known approach widely supported in the literature with
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tation with either a grafting or a graftless approach. long-term predictability. The limitations of this option are
the time to the final rehabilitation, morbidity and the impos-
Option A – Placement of six implants. Four implants are sibility of immediate loading. However, if the placement of
placed in the anterior region of the maxilla. The two posteri- four stable implants in the anterior area is possible, a serial
or implants are placed simultaneously with a bilateral sinus loading protocol with immediate loading of the anterior four
elevation procedure. Taking into consideration the reduced implants and a delayed loading after healing of the two pos-
anterior bone height, only two anterior implants can be terior implants allows a provisional immediate fixed rehabil-
placed straight in the lateral incisors position, whereas the itation, thus increasing the quality of life of the patient. It is
other two if necessary can be tilted (17-30º) to contour a pro- also important to mention that using just four implants for
eminent anterior wall of the maxillary sinus, allowing a for the final rehabilitation in Class IV, as shown in Class III Op-
an implant with a more frequent entry point in the first pre- tion B, is not recommended, because the amount of anterior
molar position. (Figure 8). bone does not allow a good biomechanical load distribution
of the implants, which could compromise long-term predict-
ability. One of the fundamental criteria for choosing Option B
with pterygoid implants in the posterior region is the pres-
ence of maxillary sinus pathology, which increases the risk of
biological complications in cases of Schneiderian membrane
rupture and situations when posterior support is required for
immediate loading. Both rehabilitation schemes represent
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a more complex surgical approach than those proposed for
Class III. Although both are predictable, Option B is recog-
nized as a less invasive approach, thus avoiding the higher
morbidity associated with bone regeneration procedures.
However, this technique requires a more trained and experi-
enced surgeon. For a more predictable immediate loading
Figure 8. Example of Maxilla CC Class IV, Option A and protocol or whenever a distal cantilever extension should be
Mandible CC Class III, Option B
avoided, Option B may be considered more appropriate. In
contrast, clinical conditions associated with a compromised
mouth opening or a reduced inter-occlusal space should ex-
clude this option.

Maxilla CCV
Anterior – severe resorption: height <8 mm or width <6 mm
Posterior – severe resorption: height <4 mm or width <6 mm
This class is characterized by severe anterior and posterior
bone resorption. In the anterior region, the bone height meas-
ured from the osteotomy level, with a <6-mm crestal width, to
the inferior border of the nasal cavity is <8 mm. Due to exten-
sive bone resorption or atrophy, the osteotomy procedure is
smaller or not conducted. In the posterior region, the bone
Figure 9. Example of Maxilla CC Class IV, Option B and height measured from the alveolar ridge, with a <6-mm crest-
Mandible CC Class II, Option B
al width, to the inferior wall of the maxillary sinus is <4 mm.