The Necessity of Pterygoid Implants?
Today, any dentist with proper education and training routinely places conventional dental implants in patients with sufficient bone conditions. But if the patient is present with the severe bone loss they are not able to attend such patients. Therefore the patient is left with no option other than removable dentures or bone graft surgeries.
What Are the Causes of Failure of Conventional Implants Leading to the Evolution of Pterygoid Implants
- Tear of sinus membrane during sinus lift procedures,
- Seepage of bone grafts into the sinus
- Loss of bone grafts due to resorption during the bone augmentation procedure
- High morbidity seen in zygomatic implants
- Screw loosening or breakage in tilted implants
What Is the Difference Between Pterygoid and Tuberosity Implants?
There is a significant difference between pterygoid and tuberosity implants. Pterygoid implants are engaged in the dense cortical part of the pterygoid bone and the palatal bone, while tuberosity implants are directed and engaged in the cancellous maxillary bone of poor quality.
Though the maxillary tuberosity is known to have the lowest bone density in the oral cavity, it rests against a denser mass of cortical bone formed by the part of palatine bone and sphenoid bone. Going by definition, all ‘pterygoid implants’ encompass the tuberosity region, but all ‘tuberosity implants’ do not necessarily engage the pterygoid process.
What Are the Advantages of Using Pterygoid Implants?
Placement of dental implants in the pterygoid region provides posterior bone support for the prosthesis, without sinus floor augmentation, and can achieve a better distribution of masticatory forces in comparison to conventional maxillary implants. This benefit allows rehabilitating patients with satisfactory full arch fixed maxillary prosthesis, which usually spanned from the second molar to the second molar.
Facts About Pterygoid Implants
The pterygoid implant is anaxial implant placed through the maxillary tuberosity with fixation apically in the pterygoid process of the sphenoid bone and the pyramidal process of the palatine bone. Pterygoid implants were first proposed by Linkow in 1975 and the method was first described by JF Tulasne in 1992. Pterygoid implant passes through the maxillary tuberosity and the pyramidal process of palatine bone to engage the pterygoid process of the sphenoid bone, its length ranges from 16 to 20 mm, they have a pointed, self-tapping apex to ensure strong anchorage when inserted.
Technique of Placement of Pterygoid Implant
The incision design is such that the entire tuberosity, including its posterior aspect, is uncovered for visualization and instrumentation.
The drill entry point is often marked 3-4 mm in front of the posterior region of the tuberosity. The drill axis runs towards the palate at about 20-30° in the horizontal plane and about 45° from the maxillary plane. Drilling with a pilot drill continues up to the pterygopalatine-tuberosity suture, which is the anchorage region for a pterygoid implant. Three different types of drills are used for insertion. All preparation is done in an underprepared mode, at a working speed of 600 rpm or manually.
The implant is then inserted manually using a bone condensation technique, due to its self-tapping and compressive characteristics. The implant is anchored in the pterygoid plate of the sphenoid bone, through the maxillary and palatine bones and with distal angulation between 35° and 55°.
