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

therapeutic options is >12 mm and <16 mm. The posterior region is characterized
Due to moderate posterior bone resorption and a slight prom- by advanced bone resorption. The bone height measured
inence of the maxillary sinus anterior wall, either a straight or from the alveolar ridge with a >6-mm crestal width to the
a distally tilted implant could be considered in the fixed full- inferior wall of the maxillary sinus is >4 mm and <8 mm.
arch rehabilitation schemes.
therapeutic options
Option A – Placement of six straight equidistant implants. The inter-antral distance and the available bone height are
Four implants are placed in the area limited by the anterior less favorable in this type of maxillae. The residual posterior
wall of the sinus, in the lateral incisor and first premolar po- bone height determines two types of fixed full-arch rehabili-
sitions. Two shorter implants are placed in the posterior re- tation schemes.
gion in the first molar position.
Option B – Placement of four straight implants in the region Option A – Placement of six implants in the maxilla. Two
limited by the anterior wall of the maxillary sinus, in the lat- straight implants are placed in the lateral incisors position,
eral incisor and first premolar positions. The posterior im- two distally tilted implants in the premolar position and two
plants with the same length are tilted at a 17°- angle follow- short implants (> 4 mm and < 8 mm) in the posterior region in
ing the slope of the anterior wall maxillary sinus. The the molar position, allowing second molar occlusion without
implant’s entry point is the first molar position with its apex cantilevers (Figure 6).
in the second premolar position. Option B – Placement of four implants in the region limited by
Option C – Similar to the Option C of the CCI Class. the anterior wall of the maxillary sinus. Taking into account
deciding factor the variable slope of the anterior maxillary sinus wall, the dis-
The main deciding factor for choosing Option A or B is the tally placed implants should tilt at an angle of 17-30°. These
arch extension size, the maxillary sinus geometry and par- implants usually emerge at the second premolar and are
ticularly poor bone quality. To avoid cantilever extensions, guided by the anterior maxillary sinus wall. An extended 14-
the posterior implant is placed in the molar position and, as mm cantilever reaching a first molar occlusion can be expect-
this location has moderate resorption (height >8 mm and ed in the full-arch rehabilitation (Figure 7).
<12 mm; width >6 mm), a tilted implant can be placed to Option C – Placement of a full-arch overdenture supported by
reach bone of better quality, instead of placing a shorter im- four implants. Since the inter-antral distance is limited, the
plant in a compromised bone. 33,34 In larger edentulous arch- mesiodistal space between the implants is short. The implants’
es with a more pneumatized maxillary sinus and compro- entry points are in the central incisors and canine positions.
mised posterior bone quality, Option B would be preferable. deciding factor
In Option B, there is an increased A/P spread distance and, The deciding factors for choosing Option A or B are the eden-
thus, a reduction in the cantilever length extension in cases tulous arch extension and the posterior bone quality. In larger
where the natural opposing arch extends to the second mo- edentulous arches, Option A might be preferable. Placing a
lar position. short posterior implant increases the A/P spread distance.
Distal cantilever extension is short or absent and might be
Maxilla CCIII considered in patients with natural opposing arch with a sec-
Anterior – moderate resorption: (height >12 mm and <16 mm; ond molar occlusion, patients with parafunctional habits or
width >6 mm) when low bone density is found in the posterior maxillae. Op-
Posterior – advanced resorption: (height >4 mm and <8 mm; tion B can be considered when the posterior bone quality
width >6 mm) does not allow placing a short implant, when grafting proce-
Moderate bone resorption is observed in the anterior region. dures should be avoided or if a second molar occlusion is un-
The bone height measured from the osteotomy level, with a necessary and the four implants are positioned to assure a
>6-mm crestal width, to the inferior border of the nasal cavity stable fixed full-arch rehabilitation. 35,36

Figure 6. Example of Maxilla CC Class III, Option A and Figure 7. Example of Maxilla CC Class III, Option B and
Mandible CC Class III, Option A Mandible CC Class III, Option B