Mini Dental Implants: Benefits, Limitations, and Insights

Advances in dental implants have increased the selection of implant designs, as well as scientific understanding of which design is best suited for a specific clinical condition. Practitioners and patients have also benefited from increased longevity of implant-supported prostheses, better esthetics, and a more sophisticated understanding of the pathogenesis of peri-implant disease. Yet there remains much to learn, including predictable protocols for treating peri-implantitis, risk factors, and a better understanding of the limitations of implants with smaller diameters and lengths, such as mini implants.

The ease of placement of mini implants has increased their use for a variety of clinical situations, including replacement of load-bearing posterior teeth. The standard root form endosseous implant can range in diameter from 3.5 to 7 mm, and from 5 to 16 mm in length. With respect to implants of less than 3.5 mm diameter, there is potential for confusion regarding terminology; for example, mini versus narrow diameter versus small diameter versus reduced diameter. The terms mini, narrow and small diameter implant are commonly used by clinicians and the literature to describe implants with diameters ranging from 1.8 to 3.3 mm.^1–4 The term reduced diameter is more general in that it can refer to any implant within the range of 1.8 mm to 3.5 mm diameter, which includes mini and/or narrow diameter implants. More recent literature has begun to use the term reduced diameter.

The length of mini and standard implants is similar. The reduced diameter of the mini implant enables use of less complex surgical techniques, as they can be positioned in areas with decreased bone thickness and without surgical reflection of a mucoperiosteal flap and/or bone augmentation. The quantity and quality of bone available in the jaw typically defines the characteristics (diameter and length) and number of implants. Thus, mini implants are often used to replace mandibular incisors because the alveolar bone is generally thin in the facial-lingual dimension. Another common application is using mini implants for support of overdentures.^5,6 However, one might question their use in replacement of posterior teeth — especially molars — that are subject to increased bite pressures during mastication.

In the next edition of Perio Update, a case report of the failure of two mini implants used to replace a single mandibular first molar will be presented. The failure resulted in surgical removal of both implants, osseous grafting, and, eventually, replacement with a conventional sized implant. In addition to the case report, the discussion will focus on possible reasons for failure of mini implants when used for posterior tooth replacement.

References

1. Shatkin TE, Shatkin S, Oppenheimer BD, Oppenheimer AJ. Mini dental implants for long-term fixed and removable prosthetics: a retrospective analysis of 2514 implants placed over a five-year period. Compend Contin Educ Dent. 2007;28:92–99.
2. Bidra AS, Almas K. Mini implants for definitive prosthodontic treatment: A systematic review.J Prosthet Dent. 2013;109:156–164.
3. Klein MO, Schiegnitz E, Al-Nawas B. Systematic review on success of narrow-diameter dental implants. Int J Oral Maxillofac Implants. 2014;29(Suppl):43–54.
4. Flanagan D, Mascolo A. The mini dental implant in fixed and removable prosthetics: A review. J Oral Implantol. 2011;37(Spec Issue 1):123–132.
5. Lemos CA, Verri FR, Batista VE, Júnior JF, Mello CC, Pellizzer EP. Complete overdentures retained by mini-implants: a systematic review. J Dent. 2017;57:4–13.
6. Jawad S, Clarke PT. Survival of mini dental implants used to retain mandibular complete overdentures: systematic review. Int J Oral Maxillofac Implants. 2019;34:343–356.

This information originally appeared in Beaini NE, Cobb CM. Avoiding complications with mini implants. Decisions in Dentistry. 2021;7(7):31–34.