The MDI is a one-piece implant that does not require a separate abutment. This simplifies the restorative phase resulting in a reduced cost for the patient. The MDI implant is made of a titanium-aluminum-vanadium alloy for increased strength. The MDI was initially designed for temporary prosthetic stabilization during the healing phase of standard implants.
The MDI is also used for orthodontic anchorage and temporary fixation of transplanted teeth. Its success in these procedures has led to its use in long term fixed and removable dental prostheses. Conventional implant treatment requires adequate bone width and inter-dental space. Augmentation procedures can be used to overcome these problems, but these techniques are complex and can cause post-operative pain and discomfort for the patient as well as incurring additional costs. The mini dental implant can be used in many such cases to overcome these kinds of limitations.
Although the mini dental implant has a reduced surface area compared with a conventional endosseous implant, histology has shown that the MDI implant undergoes osseointegration. The percentage bone to implant contact for MDI is comparable to conventional implants. The narrow diameter of the MDI allows a simplified insertion technique involving placement without raising a flap and immediate loading.
Suggested indications for use for MDI include patients with inadequate bone width; older or medically compromised patients who would benefit from the preservation of blood flow to the implant area as a result of the flapless insertion technique; patients who wish to avoid extensive bone augmentation treatment. The relatively low cost of MDI enables the clinician to offer this treatment option to more patients.
The minimally invasive surgical insertion technique with the MDI brings greater postoperative comfort and decreased morbidity for the patient, allowing patients with health problems that preclude extensive surgical procedures the option of an implant. This ease of placement of MDI is considered to be a safety factor in its use, the ability to avoid flap surgery aids in healing as the periosteum is left undisturbed. Gingival healing is typically seen in 2 to 5 days.
After placement of the MDI a patient can have an immediate temporary denture fitted. An extended healing period with MDI is usually not necessary. One author commented that there seem to be more indications for narrow diameter implants than for the standard diameter.
The mini dental implants are particularly useful in the edentulous arch with minimal remaining bone facio-lingually; they help to stabilize removable partial dentures by eliminating rocking and improving retention; and they offer extra support and retention for fixed partial dentures. The pull-out strength of an implant has been shown to be based on its length rather than its diameter. The surface area of five MDI implants is considered to be equivalent to two traditional 3.75mm implants of equal length. In the edentulous arch multiple mini dental implants are considered to be more stable than two standard implants. The arch distribution of multiple MDI’s will better offset any fulcrum or tipping problems that can occur with two conventional implants positioned at the canine area. The MDI mini dental implant is available with either an O-ball head for use with removable or fixed dentures, or a square head for fixed prostheses or retrofitting a poorly adapted partial denture. The O-ball is considered to act as a shock absorber. The MDI is manufactured as a standard thread 1.8mm diameter, and with a modified thread and 2.4mm diameter. It comes in four lengths – 10mm, 13mm, 15mm and 18mm. The clinician should always select the longest possible MDI for the available bone to maximize stability. An absence of excessive micromotion at the bone-implant interface is required to enable the osseointegration process. It is thought that there is a critical threshold of micromotion above which a fibrous encapsulation process occurs rather than osseointegration possibly around 100μ.
Summary of findings
The MDI ‘mini dental implant’ system has acceptable clinical performance appropriate for use as a dental endosseous implant for denture stabilization. The MDI mini dental implant system offers an acceptable risk when used clinically under the intended conditions, and for the intended purpose, by a dentist with the respective knowledge, experience and state of the art education.
It can be concluded that use of the MDI mini dental implant system for denture stabilization involves low risk, and that the benefit of use of the MDI mini dental implant system outweighs this low risk.