Pterygoid Implant for Atrophic Posterior Maxilla

Abstract

Replacement of missing teeth in the posterior maxilla is always a challenge for the treating implant surgeon as the posterior maxilla has several obstacles in the form of quality, quantity, the anatomy of the maxillary sinus, and inaccessibility. To overcome these deficiencies, several surgical procedures such as sinus lift, bone augmentation, tilted implants, short implants, and zygomatic implants were tried. Since these procedures have their own limitations, pterygomaxillary region provides us an excellent place for placement of implant and rehabilitation of posterior maxilla. This case report describes the usage of the pterygomaxillary region for placement of the implant to restore atrophic posterior maxilla, without any additional surgical procedures.

INTRODUCTION

Implant dentistry has grown leaps and bounds in recent years after the successful introduction of osseointegration concept by Prof. P. I. Branemark in the early 1960s. Researchers have found that rehabilitation of missing teeth in the maxillary anterior region was far easier than a maxillary posterior segment. It has been elaborated by Albrektsson et al.[1] in their literature that posterior maxilla is a very difficult area to be rehabilitated. The reasons considered for difficulty in rehabilitating the posterior maxilla is mainly due to the anatomy of maxilla due to the presence of maxillary antrum, poor quality of bone and decreased the quantity of bone.

To overcome these difficulties, sinus lift procedures, GBR grafting with both autogenous and allogenous materials, tilted implants (all on four concepts), zygomatic implants were introduced. However, these procedures are not without complications such as tear of sinus membrane, bone grafts into sinus cavities, rejection of bone grafts, screw loosening of tilted implants, and morbidity of patients with the usage of general anesthesia for zygomatic implants.

To prevent these problems, posterior most of the maxilla near the tuberosity and behind the maxillary sinus can be utilized for placement of implants. This area is called the pterygoid or pterygomaxillary region. Placement of implants through the maxillary tuberosity and into the pterygoid plate is called as pterygoid or pterygomaxillary implants. It was introduced by Tulasne in 1992.[2]

Placement of pterygoid implants involves origination of implants in the tuberosity region and follows an oblique mesiocranial direction proceeding posteriorly toward the pyramidal process. It subsequently proceeds upward between both the wings of pterygoid process of sphenoid bone.

This aim of this case report is to elaborate the placement of the implant into the pterygomaxillary region and its use in future for prosthetic rehabilitation of atrophic posterior maxilla.

CASE REPORT

A 46-year-old female patient reported to our department with a history of advanced periodontitis and periodontally compromised left maxillary posterior teeth.

On examination, clinically and radiographically, teeth in the left maxillary posterior segment had a hopeless prognosis and were advised extraction of 14, 15, and 16. Since there was severe atrophy of posterior maxilla patient was given a choice with two implants in premolar areas and one in the pterygoid region [Figure 1].

Figure 1.

Preoperative radiograph

After obtaining consent from the patient, implant surgery was planned in relation to 14, 15, and pterygoid region. Under local anesthesia full thickness flap raised and implants were placed in the premolar and pterygoid region [Figure 2]. Implant placement in the pterygomaxillary region was done at an angulation of 45°–60° relative to the maxillary plane as described in the literature.[3] Postoperative instructions were given. The patient was evaluated with radiographs periodically and after 6 months prosthetic evaluation was done [Figure 3]. Impressions were taken and rehabilitated with a screw-retained prosthesis [Figures 4 and 5]. A final radiograph was taken along with the prosthesis at the end of the prosthetic phase [Figure 6].

Figure 2.

Implant placed in relation to 24, 25 and into pterygomaxillary region

Figure 3.

Implant with healing abutment in position

Figure 4.

Implant rehabilitated with prosthesis

Figure 5.

Implant prosthesis-labial view

Figure 6.

Postoperative radiograph

DISCUSSION

The posterior atrophic maxilla has limitations such as poor bone quality and quantity, the presence of maxillary sinus, difficulty in accessibility, maintenance of proper oral hygiene, and in some cases, extreme occlusal loading in the molar regions are evident. To overcome these limitations and deficiencies, several procedures such as sinus lift with augmentation (direct and indirect), bone augmentation with autogenous grafts (both vertical and horizontal), tilted implants (all on 4), zygomatic implants have been reported widely in literature and in our day to day practice.[4,5]

Placement of implants into the pterygo maxillary region opens new vistas in rehabilitating atrophic posterior maxilla. Due to the disadvantages such as tear of sinus membrane during sinus lift procedures, seepage of bone grafts into the sinus, loss of bone grafts due to resorption during bone augmentation procedures, high morbidity seen in zygomatic implants, screw loosening or breakage in tilted implants, a simple but effective method of replacing posterior maxilla is placement of implants in the pterygomaxillary region (pterygoid implant).

This case report shows us the simple way of replacing the atrophic posterior maxilla with the pterygoid implant. In this case report, two implants (one in first premolar biccal root and another in the palatal root of the second premolar) and one implant placed in pterygo maxillary region. This case report supports the fact placement of the implant in the pterygo maxillary region has same or higher success rate as that of other techniques.

Moreover, the implants placed in the pterygomaxillary region are at an angle, there is the nonaxial direction of forces to the implant. However, once osseointegrated, reports have shown that these pterygomaxillary implants resist all axial and nonaxial forces better than any other implants placed in the maxilla.

Furthermore, in this case report, the patient tolerated the distal position of the implant, showed neither difficulty in speech nor difficulty in maintenance of oral hygiene. It was also found that patient had difficulty in opening the mouth at the time of placement of implant prosthesis.

CONCLUSION

Restoring posterior maxilla using pterygoid implants is beneficial as these implants are stable biomechanically and there is no cantilevering of pontics. The success rate achieved with this implant compares favorably with implants used in other areas of the maxilla. Implants placed in the pterygomaxillary region gives us excellent posterior bone support without augmenting maxillary sinus nor with additional bone grafting. Within the limitation of this case report, it can be concluded that pterygoid implants have high success rate with minimal complications.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.