Atrophic Maxilla Rehabilitation Through Dental Implants Using the V-4 Strategy Associated With Guided Surgery: A Case Report and Technique Description

The use of dental implants for the rehabilitation of partially or totally edentulous patients is a safe technique with predictable outcomes in the long term.¹  However, some patients suffer from conditions that present additional challenges, such as atrophic maxilla. Minimally invasive techniques have been recommended with the objectives of reducing morbidity, shortening treatment time, and decreasing the risks associated with bone-regeneration procedures while also increasing patient acceptability. Within this context, encouraging results have been observed in techniques that employ guided surgery in the installation of short implants for atrophic maxilla rehabilitation treatment.^2–5 

Surgical guides made with virtual planning have been shown to reduce surgical morbidity while also increasing precision in the positioning of implants,^2,6,7  which is particularly important in cases of bone atrophy. In 2016, Jensen et al⁸  described techniques for placing tilted implants in the atrophic maxilla to compensate for the lack of bone volume and to avoid more invasive grafting techniques.

For maxillary arches greater than 45 mm between the anterior walls of the maxillary sinuses and with bone residue available, the authors indicate the M-4 standard approach (implants positioned within the bone envelope between the maxillary sinuses and nasal cavity and above the level of the nasal floor) (Figure 1a). In cases of maxilla with reduced arches (length less than 45 mm) and residual bone tissue available only in the intercanine zone, the V-4 strategy is indicated (Figure 1b).

Classically,⁹  for the all-on-4 technique, an anteroposterior spacing of 15–20 mm between the implants is recommended, with the anterior implants positioned in the region of the lateral and canine incisors and the posterior implants in the region of the second premolars and first molars. However, in shortened arches, the V-4 strategy is applied when the bone height available in the arch is confined to the intercanine zone. In this condition, the implants are anchored in the midline adjacent to the pyriform aperture and nasal crest and to the anterior walls of the maxillary sinuses, thus enabling the use of longer implants.

Considering the limitation of the arch perimeter and proximity to anatomical structures observed during the V-4 approach, planning and execution of the procedures can be optimized by the use of tools that increase efficiency and safety while also reducing the time required for rehabilitation. This case report thus aims to describe an alternative technique that associates the V-4 strategy with guided surgery for the rehabilitation of atrophic maxilla.

This case report followed CARE guidelines.¹⁰  Patient J.C.A. (male, 73 years old), with edentulous maxilla classified as class V by Cawood and Howell,¹¹  and with a lower removable partial denture, was seen at the Brazilian Air Force dental clinic in Rio de Janeiro.

After tomographic analysis, bone volume was observed to be insufficient for the placement of implants for fixed total rehabilitation. The arch perimeter was measured using an occlusal view from the anterior wall of the right maxillary sinus to the anterior wall of the contralateral maxillary sinus, obtaining a value of 43 mm. The arch was classified as reduced, thus indicating the V-4 strategy with the placement of anterior implants tilted to the midline and tangent to the pyriform aperture and posterior implants inclined medially tangent to the anterior walls of the maxillary sinuses. To increase the precision of the procedure and to reduce morbidity, the V-4 strategy associated with guided surgery was proposed for the case. Figure 2 illustrates the modification of the technique described by Jensen et al,⁸  associating the V-4 strategy with guided surgery.

After the guided surgery planning steps, which included a tomographic examination, virtual surgical planning using Implant Studio software (3Shape), creating a surgical guide, and building a provisional prosthesis (Figure 3a–c), surgery was performed using the Neodent Guided Surgery system (Neodent) to place 4 conical implants with a Morse platform (3.5 × 13 mm; Helix GM, Neodent) in the second premolar/first molar and lateral/canine incisor. Significantly, this procedure did not involve incision and flap design. The surgical guide was fixed using fixation pins (Figure 3d), and placement of the implants was carried out according to the digital planning.

All implants showed primary stability greater than 45 N, and 17° angled mini-abutments (Neodent) were installed to correct the inclination of the implants and to enable the fixation of the provisional prosthesis. The provisional prosthesis was made before surgery following the virtual surgical planning. After surgery, the prosthesis was captured on the provisional cylinders, and final adjustments (polishing and occlusion) were conducted (Figure 4a–c).

The patient remained under postoperative management with monthly follow-ups until the sixth month after implant placement, when a new elastomeric impression (Express XP 3M ESPE) for making the final prosthesis with milled titanium infrastructure was performed (Figure 5a and b).

The final postoperative follow-up, which was conducted 24 months after implant placement, showed 100% implant survival, absence of marginal bone loss (Figure 5c), and no prosthetic complications.

This case report aimed to demonstrate the association of the V-4 strategy with guided surgery for the rehabilitation of atrophic maxilla. Although the V-4 approach has been previously described by Jensen et al,⁸  the present case report is the first to describe the association of the V-4 strategy with guided surgery. The association of these techniques reduces the complexity of dental implant placement in very atrophic arches while also improving precision and decreasing trans- and postoperative morbidity.

The V-4 strategy originally described⁸  involves lifting the anterior portions of the maxillary sinus floors to allow for the placement of the most distal implants. However, because guided surgery was also used in this case, access and elevation of the maxillary sinus were not necessary, thus reducing the risk of the procedure, risk of morbidity, and overall treatment time. Although they are usually unnecessary,¹²  surgical approaches to the maxillary sinuses remain an option. However, due to the precision of guided surgery procedures, there is often no need for incision and flap design, thus increasing patients' quality of life when compared with the results of freehand procedures.¹³ 

The guided placement of the implants offers greater precision when compared with freehand surgery on all axes (coronal, axial, and apical).¹⁴  This is fundamental for the correct positioning of the implants and protection of the anatomical structures. In addition, guided surgery for total rehabilitation is associated with low marginal bone loss and high implant survival.¹⁵ 

Despite previous radiographic examinations, the choice of approach is predominantly clinical at the time of surgery. If the placement of the most distal implants (always primary) is very anterior in the arch, then the V-4 strategy will be adopted due to the reduced space for the implants.⁸  The density of the paranasal cortical bone is usually sufficient for the stability of dental implants; therefore, many cases can be rehabilitated through immediate prosthetic loading, as described in this case report.

The patient in this case report had a 24-month follow-up with 100% implant survival and no significant marginal bone loss rate. Furthermore, no prosthetic complications were found. These results are compatible with medium- and long-term longitudinal studies that evaluated the V-4 strategy and that also observed high survival rates.^8,16  However, conducting prospective longitudinal studies in the future is essential for the biological and prosthetic monitoring of the technique.

In conclusion, the V-4 strategy associated with guided surgery for the rehabilitation of atrophic maxilla was presented as a precise and efficient method that resulted in faster procedures and greater postoperative comfort.

The authors declare that there was no conflict of interest during the elaboration of this work.