Rehabilitation of the atrophic posterior maxilla using tilted implants and digital planning: a case report

Introduction

Tooth loss is a common occurrence nowadays. The most common etiologies include periodontal disease, carious lesions, and dental trauma (1). This condition leads to significant problems for affected individuals, impacting both functional (2) and emotional well-being (3).

In cases involving single-tooth loss, a fixed partial restoration can be achieved by utilizing adjacent teeth as abutments. This conventional approach is often preferred when the teeth have already undergone prosthetic treatment (4), and its failure rates are comparable to those reported for single implants and implant- supported partial dentures (5). However, when these fixed restorations become very extensive, and the abutments are no longer adequate to withstand the masticatory load and the prosthetic device, it becomes necessary to perform either a fixed partial prosthesis supported by endosseous implants or a removable partial denture.

Endosseous implants associated with screw-retained prostheses are among the primary rehabilitative solutions for edentulous patients, offering a high survival rate (6) and ensuring high patient satisfaction (7).

However, implant rehabilitation of the posterior maxilla remains a common challenge in implant dentistry, often complicated by bone atrophy and maxillary sinus pneumatization, which significantly reduces the available bone volume for implant fixture placement (8). Among the most used approaches to rehabilitate this challenging area is maxillary sinus floor elevation, which can be performed via a lateral approach (9) or a transcrestal approach (10, 11). While these techniques show favorable success rates (12, 13), they require a high-skilled operator, often lengthen operating times, and can lead to various complications (14, 15).

An additional alternative involves bone regeneration techniques using bone grafts (16). Although effective, these procedures are invasive, entail prolonged healing periods, pose notable risks, and exhibit variable success rates (17, 18).

The use of tilted implants has gained popularity in recent years as a minimally invasive strategy for both sectoral (19, 20) and full-arch rehabilitation (21). This approach allows the use of residual bone, avoiding bone regeneration procedures. Initially introduced for total rehabilitations (e.g., in the All-on-Four protocol) (22, 23), this technique facilitates the placement of longer implants with angles of inclination typically ranging from 30° to 45°, thereby enhancing primary stability and ensuring a better distribution of occlusal forces. Clinical studies have reported implant survival rates exceeding 95% in medium- and long-term follow-up (24, 25).

The integration of 3D planning software has further optimized this approach, enabling a precise preoperative evaluation of bone anatomy and the virtual simulation of implant placement (26, 27). This digital workflow significantly reduces intraoperative risks and improves prosthetic accuracy (28). In sectoral rehabilitations for patients with moderate-to-severe posterior maxillary atrophy, where complications such as sinus perforation pose a high risk, the precision afforded by digital planning is crucial.

This case report describes the sectoral rehabilitation of the posterior maxilla in a patient presenting with bone atrophy. The rehabilitation procedure involved the placement of both axial and tilted implants according to a preoperative digital plan generated with 3D planning software. The aim is to highlight the clinical benefits, the procedures adopted, and the short- term outcomes of this approach.

Materials and methods:

A 59-year-old female patient presented to our attention with a negative general anamnesis. The patient’s main complaint and need were to rehabilitate aesthetic and masticatory function via an implant-supported prosthetic solution in the posterior maxilla, specifically in the second quadrant.

Intraoral clinical examination reveals the presence of a previously fabricated metal-ceramic prosthetic bridge on natural teeth, extending from element 2.4 to 2.7. The bridge was supported by elements 2.5 and 2.7, with an extension to element 2.4 and a pontic at site 2.6. The bridge shows mobility, presumably due to destructive carious lesions affecting the supporting abutment teeth.

Consequently, a preliminary radiographic assessment, consisting of an Orthopedic CT (OPG), was performed to confirm the clinical hypothesis. The OPG revealed a significant loss of both bone support and dental substance, thus rendering the avulsion of the prosthetic bridge’s abutment teeth advisable.

In agreement with the patient, to restore normal function, the decision was made to proceed with a three-implant, screw-retained implant-prosthetic rehabilitation. To avoid more invasive surgery, such as a maxillary sinus lift, which would otherwise be necessary given the limited bone support, and to avoid placing implants in post-extraction sites, three implants with sinus bypass are planned: one straight implant at the position.

2.4 and two tilted implants at positions 2.6 and 2.7, with immediate loading.

To support the proposed rehabilitation plan, a second-level examination, such as CBCT (Cone Beam Computed Tomography), was performed to verify maxillary anatomy, residual bone thickness, and height, to ensure the implants were inserted in the correct position.

Using three-dimensional CBCT images, the surgery was planned using a dedicated 3D software that virtually simulates implant placement and determines the optimal inclination and inter-implant distance. The virtual design also included the pre-visualization of the prosthetic components supporting the final restoration, such as digital abutments, as part of the virtual modeling of the immediate loading rehabilitation plan.

In accordance with the guidelines, the oral cavity was decontaminated before surgery with a scaling and root planing session. Furthermore, based on preoperative antibiotic prophylaxis protocols, the patient was prescribed 2 g of Amoxicillin to be administered one hour before surgery to reduce the risk of failure, a long with rinses using 0. 2 % Chlorhexidine morning and evening for three days before reduce the oral bacterial load.

The surgical procedure, performed under local anesthesia (1:200,000), involved the extraction of teeth 2.5 and 2.7, followed by a thorough revision of the alveolar sockets to remove any residual granulation tissue, which could be responsible for postoperative infections, and the simultaneous insertion of collagen sponges to support clot formation. As planned, a crestal incision access flap was raised to facilitate better soft-tissue management and improve visualization of the surgical site.

Implant site preparation was done using dedicated drills with increasing diameter, with constant irrigation using physiological saline solution to remove bone debris. Subsequently, a Winsix K25 straight implant (3.8 mm diameter, 15 mm length) was inserted at site 2.4, along with the two 35° tilted Winsix K25 implants (3.8 mm diameter, 15 mm length) at sites 2.6 and 2.7. All implants achieved an insertion torque greater than 30 Ncm.

The Winsix abutments were then placed, the flap was sutured, and the pre-The fabricated screw-retained prosthetic framework was positioned immediately.

The patient was discharged with standard postoperative recommendations and continued antibiotic therapy for 7 days post-surgery, consisting of Amoxicillin 500 mg administered three times daily.

Subsequent follow-up visits confirmed complete healing of the surgical wound and successful osseointegration of all three implants. This allowed for The delivery of the definitive prosthetic rehabilitation three months after the surgical intervention.

Results

The placement of angled implants supporting screw-retained prostheses for the rehabilitation of the posterior maxillary sector shows high clinical reliability.

The use of 3D planning software enabled highly precise planning of the final implant position, accounting for future prosthetic emergence. The final accuracy was extremely high.

Discussion

The rehabilitation of the atrophic posterior maxillary sector presents several difficulties related to the limited available bone height and the proximity of the maxillary sinus. Conventional methods to overcome this limitation, such as maxillary sinus floor elevation or bone grafting, while proven effective, can increase patient morbidity, overall treatment time, and the risk of complications (29). In the present case, the posterior area of an atrophic maxilla was successfully rehabilitated through the placement of one axial and two tilted implants, supported by pre-operative planning performed with dedicated 3D digital software.

The strategic decision to insert two tilted implants at positions 2.6 and 2.7, in conjunction with a straight implant at 2.4, maximized residual bone utilization, thereby eliminating the need for a maxillary sinus lift procedure. This technique, which has demonstrated high long-term implant survival rates (30), proved fundamental for minimizing surgical invasiveness and optimizing healing times. Furthermore, this approach allowed for placement of 15 mm long implants, contributing to improved biomechanical stability and favorable occlusal load distribution, as widely documented in the literature regarding tilted implant rehabilitations (31–32).

A key element for clinical success was the use of 3D planning software for preoperative design. As previously highlighted, digital planning ensured extreme precision in implant positioning, a critical factor in areas adjacent to the maxillary sinus. The virtual simulation enabled determination of not only the optimal angle and depth for the tilted implants but also previsualization of the final prosthetic emergence, thereby facilitating subsequent prosthetic phases. The achievement of a high insertion torque during implant placement enabled safe immediate loading, providing the patient with an immediate functional and aesthetic solution and increasing satisfaction rates.

This case supports the effectiveness and predictability of using angled implants in the atrophic posterior maxilla. This approach, combined with digital planning, makes rehabilitation minimally invasive and clinically superior, with reduced treatment times and improved patient quality of life, representing a valid and safe alternative to bone grafting procedures.

Conclusions

The edentulous and atrophic posterior maxilla leads to a severe functional deficit for the patient. While this condition can be treated with various surgical techniques, the choice of treatment must consider factors such as cost, complexity, treatment time, and invasiveness.

This clinical case demonstrates how this condition can be safely and predictably rehabilitated with tilted and axial implants.

By strategically employing tilted implants, we were able to utilize the patient’s existing bone and successfully bypass the maxillary sinus, enabling the placement of longer implants. This approach effectively avoided the increased operative time and invasiveness associated with bone grafting or maxillary sinus lift techniques.

When this type of rehabilitation is supported by rigorous 3D digital surgical planning, the clinical approach is simplified.

The precision of the software planning was fundamental in ensuring optimal implant placement and high primary stability, thereby allowing immediate loading of the implants with the provisional prosthesis.

In conclusion, the use of tilted implants, in combination with axial implants and 3D design software, represents a minimally invasive strategy that significantly reduces treatment times and patient morbidity, offering a functional and durable solution for edentulism in the posterior sectors of atrophic maxillae.