Prosthetic Rehabilitation of Atrophic Maxilla by Extrasinus Zygomatic Implants: An Illustrative Case Report

ABSTRACT

Prosthetic rehabilitation of severely atrophied jaws remains a major challenge in implant dentistry. Zygomatic implants offer a viable alternative where conventional implants are not feasible. We present the first documented case of zygomatic implant rehabilitation using the extrasinus technique in Nepal. A 49‐year‐old male with severe maxillary atrophy was treated with two anterior conventional implants and two zygomatic implants, while the mandible received four implants. The patient was rehabilitated with a Malo bridge and hybrid prosthesis. The patient was followed up for 6 years; the implant showed excellent stability with no clinical or radiographic signs of complications, and the patient reported a high level of satisfaction with the functional and aesthetic outcomes.

Key Clinical Message

This case illustrates clinical decision‐making in a low‐resource setting and suggests that advanced zygomatic implant protocols may be feasible and safe in such environments despite limited infrastructural support and resources.

1. Introduction

Patients with a completely or partially edentulous maxilla who lack sufficient bone volume may benefit from zygomatic fixtures [1]. Conventional dental implants are insufficient to ensure a fixed prosthesis and effective anchorage in cases of maxillary bone insufficiency [2]. Higuchi and Brånemark et al. proposed zygomatic implants to aid in prosthetic rehabilitation for patients who had experienced trauma, deformity, or tumor‐induced maxillary atrophy and enhanced pneumatization [3].

Promising results have been observed with zygomatic implants, providing anchorage and stability in the zygomatic bone, which is a cortical bone with a dense trabecular structure [4]. For these reasons, some authors have proposed using zygomatic implants as a form of permanent rehabilitation for edentulous patients [1, 3].

Although the original placement technique suggests anchoring the zygomatic implants in the maxillary sinus [3], various implant fixation techniques are developed to improve the positioning of the implants with respect to the alveolar ridge that are beneficial for prosthetic rehabilitation [5, 6]. The extra‐maxillary surgical technique positions the zygomatic implant outside of the maxillary sinus, leaving its lateral maxillary surface only covered by soft tissue [7]. It results in preservation of the Schneiderian membrane and a decreased vestibular‐palatine width of the prosthesis due to the more coronal emergence of the zygomatic implant [8].

To the best of our knowledge, this represents the first reported instance of extrasinus zygomatic implant placement in Nepal. The primary rationale for reporting this case is to demonstrate how internationally recognized protocols can be effectively adapted to a resource‐limited local context, where such advanced procedures are seldom performed. It also emphasizes the importance of developing region‐specific clinical guidelines and enhancing training in advanced implant techniques.

2. Case Presentation

2.1. History and Clinical Examination

A 49‐year‐old male patient presented with partial edentulism in both the maxilla and mandible, having been edentulous for over 10 years. He had a history of using removable dentures with poor retention and stability, which prompted him to seek a fixed prosthetic solution. The patient was in good overall health, with no significant underlying medical conditions. However, the extent of maxillary sinus pneumatization for his age was unusual and added complexity to the treatment planning process.

2.2. Investigations

Radiographic and cone‐beam computed tomography imaging showed significant bone loss in the maxilla, including vertical and horizontal deficiencies, as well as bilateral maxillary sinus pneumatization (Figure 1). During treatment planning, we discussed various alternatives with the patient, including conventional extensive bone grafting procedures such as autogenous bone harvesting. However, the patient expressed a clear preference to avoid these invasive procedures due to the increased surgery and healing time. Based on this preference and the clinical feasibility, we opted for the All‐on‐4 protocol with a combination of conventional and zygomatic implants. This included placement of two anterior conventional implants and two angulated extra sinus zygomatic implants in the posterior maxilla, along with two posterior tilted and two anterior conventional implants in the mandible.

FIGURE 1.

(A) Cone‐beam computed tomography (sagittal slices) showing significant bone loss in the maxilla, including vertical and horizontal deficiencies. (B) 3D reconstruction showing lateral view of the zygomatic bone and zygomatic process on right side. (C) 3D reconstruction showing lateral view of the zygomatic bone and zygomatic process on left side.

Due to infrastructural limitations, digital planning software and surgical guides were not utilized. The surgical planning was carried out using conventional methods, including radiographic markers and clinical assessment of anatomic landmarks. Implant angulation and trajectory were determined by carefully evaluating the patient's maxillary anatomy through a combination of clinical palpation of the zygomatic buttress and detailed analysis of the CBCT scans on a conventional viewer, focusing on parasagittal and coronal slices to assess bone volume and sinus anatomy.

Preoperative laboratory tests and anesthetic evaluations were completed. The surgery was performed under general anesthesia in an operating theater.

2.3. Surgical Procedure

The surgery was initiated after the administration of local anesthesia using 4% articaine with 1:200,000 epinephrine. A full‐thickness mucoperiosteal flap was raised following a mid‐crestal incision (Figure 2). Two conventional implants (4.0 × 13 mm) were placed in the regions of teeth 12 and 22.

FIGURE 2.

Full‐thickness mucoperiosteal flap reflection.

In the posterior maxilla, the extrasinus technique was performed. After the flap was raised, the lateral wall of the maxilla and the zygomatic buttress were exposed. The implant osteotomy was initiated with a lance drill, followed by a series of pilot and twist drills to create the precise pathway for the implants. Copious sterile saline irrigation was used throughout the drilling process to prevent bone overheating. Two zygomatic implants (NobelZygoma 45 degree, 40 mm, and 42.5 mm) were then inserted using the extrasinus technique with a final torque of 50 Ncm (Figure 3). The chosen implant system was selected based on its established clinical success, availability in our region, and a robust protocol that is well‐suited for a non‐digital workflow.

FIGURE 3.

Placement of two zygomatic implants in position.

In the mandible, two conventional implants Nobel Active (4.2 × 13 mm) were placed in the regions of 32 and 42, and two tilted implants Nobel Active (4.2 × 15 mm) were placed at 35 and 45 (Figure 4). Multi‐unit abutments with 2 mm healing caps were attached to both zygomatic and conventional implants. The flaps were sutured using 5–0 monofilament nylon sutures. The estimated surgical duration was approximately 2.5 h, and intraoperative blood loss was minimal. The immediate postoperative care included a cold compress and standard pain medication. The final implant positions were confirmed using a postoperative panoramic radiograph (Figure 5).

FIGURE 4.

Placement of four mandibular implants in position.

FIGURE 5.

Panoramic radiograph confirming the final placement of implants.

2.4. Prosthetic Workflow

The prosthetic workflow was as follows:

• After adequate healing of the soft tissue (approximately 2 weeks), multi‐unit impression copings were attached and splinted using orthodontic wire and low‐shrinkage auto‐polymerizing resin to ensure stability (Figure 6).

• A polyvinylsiloxane impression was taken for accurate transfer of implant position (Figure 7).

• The patient's existing denture was modified and relined to serve as a provisional restoration, which was delivered within 24 h post‐surgery for immediate function.

• After a 6‐month healing period, the definitive prostheses were fabricated: a screw‐retained titanium Malo bridge with individual zirconia crowns for the maxilla and a titanium bar‐supported hybrid prosthesis for the mandible (Figure 8). Occlusal considerations included a balanced occlusion with canine guidance to minimize lateral forces on the prostheses.

FIGURE 6.

Jig Trail done using low‐shrinkage auto‐polymerizing resin.

FIGURE 7.

Polyvinylsiloxane final impression.

FIGURE 8.

Titanium Malo bridge in maxilla and titanium bar with hybrid prosthesis in mandible.

2.5. Outcome and Follow‐Up

At the 2‐week, 3‐month, 6‐months and 6‐years follow‐ups, all implants showed excellent primary and secondary stability, with no clinical signs of inflammation, mobility, or radiographic evidence of peri‐implant bone loss. The soft tissue was healthy, and the prostheses functioned satisfactorily.

The patient was followed for a total of 6 years after the surgery. Patient satisfaction was assessed at the final follow‐up using a subjective, unvalidated scale from 1 (very dissatisfied) to 10 (very satisfied). The patient rated his satisfaction as 9/10 based on function, esthetics, and comfort (Figure 9).

FIGURE 9.

Final result showing implant supported denture in position.

Postoperative clinical and radiographic examinations were conducted to assess sinus health. The patient reported no symptoms of sinusitis, such as facial pain, discharge, or congestion. At 6‐years follow‐up, the panoramic radiograph (Figure 10) was taken, which showed no signs of implant encroachment into the sinus cavity, and the patient's overall sinus health was deemed clinically normal.

FIGURE 10.

6‐year follow‐up panoramic radiograph showing no signs of implant encroachment into the sinus cavity, and the patient's overall sinus health.

3. Discussion

The biomechanical environment in which implants function plays vital role in determining their viability and efficiency. Increasing the anterio–posterior spread of implants, placing longer implants, and optimizing the number of implants can reduce the strain on the crestal bone. The “All‐on‐4 concept” developed by Paulo Malo offers an alternative treatment option to traditional dentures for completely edentulous patients by enabling immediate full arch restoration supported by only four implants. This approach involves placing two axial implants in anterior region and two tilted implants posteriorly. Tilted implants are particularly advantageous in cases of severe maxillary resorption, as they eliminate the need for sinus floor augmentation [9]. Restoring functional dentition in a patient with a severely atrophied maxilla remains challenging. Conventional approaches like sinus lifts, ridge splits, onlay bone grafting using autogenous iliac crest bone, and even Lefort I surgical downfracture with interpositional bone grafting have been widely practiced [10]. However,these techniques are associated with increased surgery and healing time, infection risk, and graft donar site morbidity [11].

Sufficient bone height and width are mandatory for successful placement and retention of functional dental implants. In the present case, sufficient bone was available in Bedrossian Zone 1 & 2, whereas Zone 3 exhibited insufficient bone due to pneumatization of sinus. Based on the guideline for optimal implants placement, conventional implants in the maxillary anterior region and tilted zygomatic implants in the posterior region were planned [12] (Table 1) (Figure 11).

TABLE 1.

Guidelines for optimal implants placement.

Bone present for implants	Posterior surgical approach
Zone 1, 2, 3	Traditional implants
Zone 1, 2	Inclined implants, posterior implants Traditional anterior implants
Zone 1 only	Zygomatic implants or sinus‐inlay grafting followed by implants Traditional anterior implants
Insufficient bone in any zone	4 zygomatic implants or Branemark horseshoe graft followed by tradional implants

Source: Bedrossian et al. [12].

FIGURE 11.

Bedrossian three zones of maxilla.

Branemark System in 1988 described a standard surgical technique for intra‐sinus placement of zygomatic implants [3]. The success of zygomatic implants is appreciable as it provides retention passing through 3–4 cortical layers of bone unlike most traditional implants [13]. Pellegrino G et al. in their study reported that posterior implant sites show greater malar bone engagement (≈22–26 mm) compared to anterior sites (≈18–22 mm), indicating that implant position significantly influences biomechanical support [14]. Intra‐sinus approach of zygomatic implant presents drawbacks such as poor surgical visualization, long surgical time due to the necessity of lifting the sinus membrane, risk for sinus adverse events, poor and/or inadequate emergence profile of the prosthetic abutment due to the palatal positioning of the platform of the zygomatic implants, and reduced anchorage in the zygomatic bone [15]. Stella and Warner introduced a more straightforward technique that avoided both antrostomy and sinus membrane elevation [16]. The technique was later criticized by Boyes‐Varley et al. who argued that visualization of the entrance of the implant into the zygomatic bone is important to avoid complications [17].

Furthermore, reports of the high success rates of the extrasinus approach for zygomatic implant implantation have been made [5]. The extrasinus approach enhances prosthesis results and streamlines surgical procedures. This method enhances operative visualization, decreases surgical time, and lowers the likelihood of sinus adverse events by placing the zygomatic implant outside the maxillary sinus. When the zygomatic implant platform emerges and is positioned on the crest of the remaining ridge, typically in the first molar or second premolar region, the restoration's prosthetic profile is significantly enhanced [18]. The long‐term impact of exposed threads on the soft tissue at the lateral side of the zygomatic implants could be one challenge with the extrasinus procedure. In contrast to totally submerged implants, Lekholm and colleagues did not find any higher marginal bone loss or failure rate for machined implants with exposed threads during implant operation [19]. In a systematic review evaluating 25 clinical studies on implants placed in the zygomatic bone for maxillary rehabilitation, Goiato et al. found that the cumulative survival rate of implants was 97.86% at a follow‐up of 2–3 years [20]. Zygomaticimplants utilized for rehabilitating patients with severe maxillary atrophy have shown favorable outcomes. Nonetheless, owing to potential complications, strict case selection is necessary, combined with regular recall visits and proper oral hygiene maintenance [21]. Due to the anatomical intricacies of zygomatic processes and limited intra operative visibility, free‐hand osteotomy of zygomatic implant often presents a significant challenge, especially for inserting multiple zygomatic implants on one side of the zygoma with little experience. A recent systematic review and a retrospective study have reported various complications, including facial hematoma, lip laceration, malposition, orbital penetration, and zygoma bone fracture, all related to the operation [22]. Similarly, Pala K et al. reported high implant survival rates (> 95%), with sinusitis being the most frequent complication (≈5%–10%). The study also indicated that optimized implant positioning and technique selection can reduce complication rates while maintaining favorable functional outcomes [23]. The accuracy and safety achieved through the free‐hand approach mainly depend on the surgeon’s experience and skills [24]. While postoperative CT scans would have offered a more detailed assessment of implant positioning, follow‐up imaging was restricted to panoramic radiographs due to limited resources. Despite this, both clinical and radiographic evaluations at 6 years indicated successful integration and functional stability.

3.1. Clinical Adaptations and Challenges in a Low‐Resource Setting

In Nepal, the availability of advanced zygomatic implant procedures is restricted by limited surgical expertise, imaging capabilities, and access to specialized equipment. This case highlights how thoughtful clinical decisions, guided by streamlined yet evidence‐based protocols, can lead to positive outcomes despite these limitations. Unlike tertiary care centers, the treatment was carried out at a regional dental clinic, where surgical navigation systems and customized prosthetic planning tools were not readily available.

In comparison to extensive studies such as those by Maló et al. [7] and Migliorança et al. [5], which present results from advanced implantology centers, our case demonstrates comparable long‐term functional and aesthetic outcomes (Table 2). This indicates that the extrasinus approach may be effectively applied even in settings with limited resources.

TABLE 2.

Comparison of current case with existing literature.

Study	Surgical technique	Implant type	Setting	Follow‐up	Complication
Present case	Extrasinus	2 ZIs + 2 CIs	Regional Nepal Hospital	6 years	None
Maló et al. [7]	Extrasinus	747 ZIs	Tertiary Center	1–7 years	Minor soft tissue issues
Migliorança et al. [5]	Extrasinus	ZIs + CIs	Private clinic	12–36 months	No major complications

Abbreviations: CIs, conventional implants; ZIs, zygomatic implants.

The key lesson learned is that while advanced technology can optimize outcomes, a thorough understanding of conventional planning principles and surgical protocols is essential for success in contexts with limited infrastructure. This experience can inform training and guideline development for clinicians working in similar environments, encouraging a focus on core surgical and planning skills.

4. Conclusions

This case report suggests that, even in a situation with limited resources, the extrasinus zygomatic implant procedure is a viable and effective choice for the prosthetic rehabilitation of a severely atrophied maxilla. The procedure offers a predictable outcome and may be less complex than extensive bone grafting procedures. While this case highlights a successful outcome in a single patient, it is essential to emphasize that further studies and larger case series are needed to validate these findings and to provide a more comprehensive long‐term prognosis. The presented results are not generalizable and should not be taken as a proof of superiority or support for the standard of care. The success of this case underscores the importance of exceptional surgical abilities and a deep understanding of the technical principles for this advanced procedure.

Author Contributions

Bidhan Shrestha: conceptualization, data curation, investigation, methodology, project administration, resources, supervision, validation, writing – review and editing. Nabina Miya: conceptualization, data curation, investigation, methodology, validation, writing – original draft, writing – review and editing. Bikal Ghimire: conceptualization, data curation, formal analysis, investigation, methodology, validation, writing – original draft, writing – review and editing.

Funding

The authors have nothing to report.

Disclosure

Patient perspective: The patient expressed high satisfaction with the successful treatment outcome, achieved without complications.

Ethics Statement

Case reports are exempt from ethical approval in our institution.

Consent

Written informed consent was obtained from the patients for the publication of this case and accompanying images.

Conflicts of Interest

The authors declare no conflicts of interest.

Data Availability Statement

Data sharing is not applicable to this article as no new data were created or analyzed in this study.