Dr. Alan MeltzerFROM THE DESK OF ALAN M. MELTZER DMD MScD
MY TAKE ON MINI-IMPLANTS
Recently there has been a resurgence in the use of mini-implants (1.8-2.4mm in diameter). These implants were originally introduced as temporary implants and are now being used as a final solution for patients. This new idea is being promoted by some opinion leaders as an inexpensive solution for patients. My only experience with mini-implants has been the removal of fractured mini-implants, so the idea of taking a one or two-day course and starting to place these flaplessly left me scratching my head.
Keeping an open mind, I read a recent article* in Compendium. I would like to share my feelings after reviewing the article. The article tracked an impressive number of implants (2,514) over a 5-year period with an average evaluation period of slightly under 3 years. The average reported survival rate was 94.2%. While impressive, it falls about 3.5% shy of our 10-year survival rate with standard and wide-diameter implants. That represents a greater than 100% increase in failure rate. Additionally, 20 implants fractured during placement and were not included in the survival analysis. If included, that would increase the failure rate by an additional 0.8%. Furthermore, the authors preclude the placement of these mini-implants in type-4 bone and D-quantity bone. These criteria represent areas where most failures occur with standard implants. If I removed short implants and implants placed in poor quality bone and include immediately loaded mandibular implants, my published survival rate jumps to 99.38%** That represents about a 500% increase in failure rate using mini-implants.
Upon further review, the article stated that the average time period for failure was about 6.4 months. Today most standard implants are loaded at about 8 weeks. Published data with standard implants demonstrate that most failures occur during the 8-week period immediately following placement. This means that most failures occur with standard implants prior to fabrication of the prosthesis, while most mini-implant failures may occur during or after prosthesis fabrication.
Several other interesting facts surfaced. First, it took three years experience with MDI placement to achieve success rates over 90%. Second, mini-implants were far more successful supporting fixed bridges, which is an expensive restoration. Third, mini-implants used to support existing dentures had only an 88% survival rate. Fourth, a larger number of mini-implants are suggested as compared to standard diameter implants. Fifth, implants placed in the posterior maxilla were 3.3 times more likely to fail. Sixth, this implant is contraindicated in extraction sockets and, therefore, should not be used for immediate placement. Finally, mini- implants placed to support removable prostheses were 4.3 times more likely to fail.
After reviewing this article, I remain of the opinion that the use of standard implants will remain my treatment of choice. Let us never forget that there are patients attached to these implants, and the best way to manage a complication is to avoid it in the first place.
I compliment the authors for a well-written objective publication.
* Mini Dental Implants For Long Term Fixed and Removable Prosthetics. Shatkin TE, etal. Compendium, Vol 28, Number 2 pp 92-99.
** A 5 Year Life Table Analysis Of A Multi Center Study Involving Immediately Loaded Implants In The Edentulous Mandible. Testori T and Meltzer AM. Clin Oral Implant Research, Vol.115, 2004.
