Shorter miniscrew implants (MSIs) make it possible to reduce the risk of root damage, increase the number of buccal placement sites, and to treat patients during the mixed dentition. The purpose of the present study was to evaluate the stability of 3 mm long MSIs placed in humans by an inexperienced operator. A total of 82 MSIs were placed in the buccal maxillae of 26 adult subjects by one operator who had previously placed only 5 buccal MSIs. Pairs of adjacent implants were immediately loaded with a 100g nickel-titanium closed-coil spring. Subjects were recalled after 1, 3, 5, and 8 weeks, at which times stability was verified and questionnaires pertaining to MSI-related pain and discomfort were completed. All MSIs were removed after 8 weeks. The failure rates of MSIs in the anterior and posterior placement sites were 35.7% and 30.0% respectively. The overall failure rate was 32.9%. 10 of 27 failed MSIs (37%) were traumatically dislodged by the subjects. Excluding these incidental failures, the failure rate in the anterior and posterior sites were 31.6% and 15.2%, and the overall primary failure rate was 23.6%. Failures were significantly (p=0.010) greater among the first half (41 MSIs) placed than the last half (46.3% vs 19.5%). All primary failures occurred on or before day 42; on average, they failed on day 24.5. Subjects experienced very low pain (2.2% of maximum) and discomfort (5.5% of maximum) during the first week only. Shorter 3 mm MSIs placed by an inexperienced operator are highly likely to fail. With clinical experience, failure rates can be dramatically improved. Pain and discomfort experienced after MSI placement is minimal and temporary.
