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A comparison of tapered and cylindrical miniscrew stability.

OBJECTIVES
This study compared the stability of tapered miniscrews with cylindrical miniscrews.


MATERIALS/METHODS
One hundred and five tapered and 122 cylindrical self-drilling miniscrews were placed into the maxillary and mandibular buccal alveolar areas of 132 patients (43 males and 89 females). The insertion torque and removal torque were measured and Periotest values (PTVs) were recorded at implantation.


RESULTS
The success rates of the tapered and cylindrical miniscrews examined were similar. In the maxilla, the insertion torque of the tapered miniscrews (8.3 Ncm) was significantly higher than that of the cylindrical miniscrews (6.3 Ncm) (P < 0.05). The PTVs of the tapered miniscrews were statistically significantly lower in the maxilla (P < 0.05). The removal torque values showed no significant difference between the tapered and cylindrical miniscrews in the upper and lower buccal areas (P > 0.05).


CONCLUSIONS
Tapered miniscrews had higher initial stability when compared to cylindrical miniscrews, whereas the clinical success rates and removal torques were similar between the two designs. The long-term stability is not directly affected by the miniscrew design.