Korean J Orthod.  2008 Jun;38(3):149-158. 10.4041/kjod.2008.38.3.149.

The effect of loading time on the stability of mini-implant

• Lee SY
• Cha JY
• Yoon TM
• Park YC

• KMID: 1975904
• DOI: http://doi.org/10.4041/kjod.2008.38.3.149

Abstract

OBJECTIVE
The purpose of this study was to investigate the stability of mini-implants in relation to loading time. METHODS: A total of 48 mini-implants (ORLUS, Ortholution, Korea) were placed into the buccal alveolar bone of the mandible in 8 male beagle dogs. Orthodontic force (200 - 250 gm) was applied immediately for the immediate loading group while force application was delayed for 3 weeks in the delayed loading group. For the subsequent loading periods (3, 6, 12 weeks), BIC (bone implant contact) and BV/TV (bone volume/total volume) and mobility test were carried out. RESULTS: The immediate loading group showed no changes in BIC from 3 to 12 weeks, while the delayed loading group showed a significant increase in BIC between 3 and 12 weeks (p < 0.05). The BV/TV of the delayed loading group significantly increased from 6 to 12 weeks of loading (p < 0.05), while the BV/TV of the immediate loading group decreased from 3 to 12 weeks of loading. However, there was no significant difference in BV/TV between experimental groups. The mobility of the immediate loading group was not significantly different from that of the delayed loading group after 12 weeks of loading (p < 0.05). CONCLUSIONS: These results showed that immediate loading does not have a negative effect on the stability of mini-implants compared to the early loading method in both the clinical and histomorphometric point of view.

Keyword

Mini-implant; Immediate loading; Delayed loading; Histomorphometric analysis

MeSH Terms

Animals
Dogs
Humans
Male
Mandible
Nitrogen Mustard Compounds
Nitrogen Mustard Compounds

Figure

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  Fig. 1 Implantation sites of orthodontic mini-implants (A) and intra-oral photo (B). Orthodontic forces to both immediate and delayed groups were loaded reciprocally with elastic chain.

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  Fig. 2 Timetable for installation of mini-implants. W, weeks; DL, delayed loading group; IL, immediate loading group; HC, healing control group.

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  Fig. 3 Subsequent photographs of mini-implants for each group after installation. Histological section showed well-organized vital bone in contact with the implant after loading. Mature lamellar bone was visible at 6 weeks. Toluidine blue; × 100; 3 w, 3 week; 6 w, 6 weeks; 12 w, 12 weeks; scale bar shows 100 um.

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  Fig. 4 Histological findings at week 6 of the immediate loading group. Intimate bone-implant contact was observed (left, × 100); osteoclast-like cell was shown at implant-bone surface (center) and bone marrow (right, × 200); B, alveolar bone; M, mini-implant.

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  Fig. 5 Bone implant contact (BIC, %) and bone volume/total volume (BV/TV, %) of each group for different time periods. *p < 0.05. IL, Immediate loading group; DL, delayed loading group; HC, healing control group.

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