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rev port estomatol med dent cir maxilofac . 2019;60(4):175-188 183

Option A – Placement of six straight implants. Two anterior can be placed. Since an angulation of 17-30° is used, their tra-
implants are placed in the lateral incisors position. Two distal jectory passes forward the mental nerve loop. In cases with a
implants are placed in the anterior region following the ana- maximum mental nerve loop length of 5.7 mm, the implant
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tomically driven approach, and their entry point must have a entry point should coincide with the mental foramen. In
safe anterior distance to the mental nerve and its possible this rehabilitation scheme, a distal 10-to-14-mm cantilever in
loop. In the posterior region, two implants are placed in the the first molar position should be considered (Figure 9).
first or second molar position depending on the functional Option C – Similar to the rehabilitation schemes proposed for
molars of the opposing dentition. Mandible CCI.
Option B – Placement of four implants. Two straight implants
are placed anteriorly to the mental foramen, in the canine deciding factor
position, and two straight implants in the posterior region, in Based on the principle proposed for Mandible CCI, the same
the first molar position. biomechanical factors support Option A without a distal can-
Option C – Use of an overdenture supported by two or four tilever. If none of the mentioned factors are present, Option B
non-splinted implants placed in the anterior region of the can be a predictable alternative approach. According to a
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mandible, in the same position as described for Option A. 3-year prospective study, no clinical differences were found
when comparing schemes similar to Mandible CCI Option B
deciding factor (four straight implants) and Mandible CCII Option B (four im-
Both of the fixed full-arch schemes do not consider the pres- plants with the posterior implants tilted). In this study, im-
ence of a distal cantilever. The extension and size of the arch plant success criteria and mechanical prosthesis complica-
are the main deciding factors for one of the options, i.e., in tions were evaluated. This work gives rise to further
large arches, Option A should be selected. Other factors like evidence-based studies to validate the Option B proposed for
the presence of parafunctional habits (bruxism and clenching) Mandible CCI.
or natural teeth in the opposing arch up to the first or second
molar may also justify that option. The rationale proposed for Mandible CCIII
a removable option follows the principles mentioned for Max- Anterior – Moderate resorption (height >12 mm and <16 mm;
illa CCI-CCIV. Several randomized clinical trials and a me- width >6 mm)
ta-analysis confirm both of the options proposed. 45-47 Thus, Posterior – Advanced resorption (height >4 mm and <8 mm;
the economic, biomechanics and clinical situation should width >6 mm)
guide the clinician and the patient in which option to choose. 27 Moderate bone resorption is found in the anterior region. The
bone height measured from the osteotomy level, with a >6-mm
Mandible CCII crestal width, to the inferior border of the mandible is >12 mm
Anterior – Available bone (height >16 mm; width >6 mm) and <16 mm. In the posterior region, advanced posterior bone
Posterior – Moderate resorption (height >8 mm and <12 mm; resorption is characterized by a bone height >4 mm and <8 mm
width >6 mm) measured from the alveolar crest, with a >6-mm crestal width,
The anterior region still has a favorable amount of available to a 2-mm safe distance from the mandibular canal.
bone. The bone height measured from the osteotomy level,
with a >6-mm crestal width, to the inferior border of the man- therapeutic options
dible is >16 mm. In the posterior region, moderate posterior Taking into consideration the advanced posterior bone re-
bone resorption is observed. The bone height measured from sorption with a short bone height and moderate anterior
the alveolar crest, with a >6-mm crestal width, to a 2-mm safe bone resorption, two fixed full-arch options and two full-arch
distance from the mandibular canal, is >8 mm and <12 mm. removable schemes are proposed.

therapeutic options Option A – Placement of four implants in the anterior region
Considering the posterior low bone availability and the favora- and two in the posterior region. The implants placed in the
ble anterior region with higher bone density, two fixed full-arch anterior region follow the surgical and prosthodontic criteria
options and two removable full-arch schemes are proposed. of Mandible CCII Option B. In addition, two short posterior
implants are placed in the first molar position (Figure 6).
Option A – Placement of six straight implants. The available Option B – Similar to Option B of Mandible CCII. Taking into
anterior bone length enables the placement of four axial im- consideration the reduced posterior bone height available,
plants. Their position and the surgical approach are similar to the entry points of the distal implants should be aligned with
those of the anterior implants proposed for Mandible CCI Op- the first premolar. In this rehabilitation scheme, a distal can-
tion A. The reduced bone height in the first molar position tilever should be considered (Figure 7, Figure 8).
requires the use of short implants in this area. Option C – Taking into consideration a reduced implant length,
Option B – Placement of four implants in the anterior region. the removable rehabilitation schemes proposed are similar to
The two most anterior implants are placed vertically in the Mandible CCI and CCII.
lateral incisors position. Taking into consideration the poste-
rior bone height availability over the mandibular canal, two deciding factor
tilted implants with entry points slightly posterior to the Regarding the bone resorption observed, the same deciding
mental foramina, usually at the second premolar position, factors of Mandible CCI and CCII should be considered. Op-