Implant-retained prosthesis is partly or completely supported by implant or implants. Dental implants have been in use for years to rehabilitate edentulous patients and their success is also proven. The overall satisfaction is 95% from the patients’ perspective. Patients report satisfactory improvements in terms of function, appearance, comfort and overall outcome of the treatment. The long-term clinical success of conventional dental implants in implant-supported overdenture is proven and recorded.
However, due to some reasons, mini dental implants are an acceptable alternative. These reasons include the bony morphology of physically debilitated and elderly patients, anatomic limitations, inadequate funds and long duration of treatment.
Mini Dental Implants (MDIs)
They are biocompatible, ultrasmall titanium alloy implant screws. The diameter of these miniature dental implants is 1.8 to 2.4 mm. The length of the mini dental implant varies from 10 to 18 cm. This is a fast, minimally invasive technique. It is becoming the system of choice to stabilize the prostheses of denture patients. The duration of treatment is minimum with peri-implant surgery omission and simple implant integration. This also makes it an affordable treatment.
The surface area of MDIs is smaller than conventional implants. A horizontal force transfers load to the bone-implant interface. This load is greater than conventional implants. The Bite force is decreased from posterior to anterior. Potential pressure peaks may be compensated by placing the implant in the anterior area of the denture. Though there is a need for more studies on clinical outcomes of MDIs, literature recorded so far does suggest that the survival of reduced diameter implants and conventional implants is identical.
A dental surgeon takes an X-ray image of the patient’s mouth. This image includes both jaws and teeth. This is followed by a radiographic evaluation of the surgical site to get an idea of bone volume and height. The surgeon decides implant sites, number, length and angulations of implants. After identifying the appropriate site for implants, the lower denture is fabricated or modified.
The surgeon uses local anesthesia. He then marks entry points for each implant on the tissues via a marker or bleeding points. A special drill called pilot drill is used on the site. The surgeon delicately places the drill over the entry point. It is lightly pumped up and down to penetrate the cortical plate. An incision is not necessary in this procedure. The surgeon uses sterile irrigation throughout the drilling procedure. He might extend penetration if the bone is extremely dense. The length of the implant and the pilot hole depth are never the same. The tip of the implant is not as wide as the tip of the drill. The surgeon uses the finger driver, rotates clockwise and exerts downward pressure to insert the implant into the pilot opening.
The procedure initiates the self-tapping. This is used until the surgeon notices bony resistance. The surgeon uses the winged thumb wrench to thread the implant into place. After some time, the wrench becomes difficult to turn. This is followed by carefully controlled, small, incremental ratchet turns for final seating. In case the bone is very dense, the surgeon unscrews and re-screws to the final position. It is important to prevent MDI from getting fracture when bone density is high. With the ideal length, the abutment head protrudes with no thread or neck portions visible. Torque during the implant placement should not exceed 50 Ncm.
To accommodate metal housing and implants, the tissue surface of denture is relieved. After trimming blackout shims to appropriate length, one shim is placed on each implant. This is followed by the placement of metal housing on each implant. The implant head is ball-shaped. There is a retaining fixture acting like a socket. The denture is seated and O-ring snaps over the ball. The surgeon then places denture in the patient’s mouth to check for passive fit. After applying a thin adhesive layer on the denture’s tissue surface, it is seated in the mouth. The patient is asked to apply normal bite pressure. The material takes around 7 to 9 minutes to set. The surgeon trims and polishes denture after removing all blackout shims. The denture must be kept in place for the next 48 hours.
MDIs are as effective as conventional implants. If you are looking for affordable dental implants then mini dental implants may be the right option for you.