Evidence-based selection of orthodontic miniscrews, increasing their success rate in the mandibular buccal shelf. A randomized, prospective clinical trial

Abstract

Background: Skeletal anchorage has made it possible to perform complex orthodontic tooth movements that are difficult or even impossible to achieve with conventional orthodontic treatment. Mandibular buccal shelf miniscrews, used for distalization, play a particularly important role in treatment of Class III malocclusion. Unfortunately, stability of the miniscrews placed in the mandible is still considered at higher risk of failure compared to other intraoral locations. The aim of our study was to determine the influence of the miniscrew size on their long-term stability, occurrence of oral mucosa inflammation and pain lasting over 48 h after implantation.

Methods: 184 Absoanchor^® miniscrews (Dentos, South Korea) in two sizes: SH2018-10 (length 10 mm, ø 1.8-2.0 mm) and SH1514-08 (length 8 mm, ø 1.4-1.5 mm) were inserted in the mandibular buccal shelf in 92 Caucasians aged 20-50 years, diagnosed with Class III malocclusion that required en-masse distalization of the mandibular dentition. Data was statistically analyzed with the level of significance set at p = .05.

Results: 91.3% of the SH2018-10 and 75% of the SH1514-08 miniscrews were stable, and this difference was statistically significant (p < .05). Inflammation of the oral mucosa was noticed around both types of miniscrews and affected 50% of the SH2018-10 and 26.09% of the SH1514-08 group (p < .05). Pain lasting longer than 48 h after implantation was related to 60.87% and 20.65% of the SH2018-10 and the SH1514-08 miniscrews (p < .05), respectively. Inflammation associated with larger SH2018-10 miniscrews did not affect their stability (p > .05), contrary to the SH1514-08 ones (p < .05). When inflammation was present, the overall success rate declined to 64.29%, from 94.74% noted for TADs without inflammation. According to the log-rank test, smaller TADs failed significantly sooner than the larger ones (p = .002).

Conclusion: Larger SH2018-10 miniscrews are the anchorage of choice for the mandibular buccal shelf, despite triggering inflammation and long-lasting pain significantly more often than the smaller ones. Therefore, this issue should be discussed with every patient prior to miniscrew use. Trial registration ID: ClinicalTrials.gov Identifier: NCT05280678 Date of Registration: 15/03/2022. Retrospectively registered.

Keywords: Mandible; Orthodontic anchorage procedures; Orthodontics.

Fig. 1

CONSORT participant flow diagram

Fig. 2

Mini-implants used in the study (from left to right): SH 1514-08 and SH 2018-10

Fig. 3

TADs allocation securing randomization. captions: R–right side, L–left side

Fig. 4

TAD insertion area

Fig. 5

Frontal cross-section of mandibular buccal shelf illustrating axial inclination of the TAD (extra-alveolar approach)

Fig. 6

Survival distribution of the mini-implants with respect to their size: SH1514-08 and SH2018-10.