Shanghai Journal of Stomatology ›› 2014, Vol. 23 ›› Issue (4): 485-488.

• Clinical Study • Previous Articles     Next Articles

Effects of premolar extractions on Bolton index overall ratios

WEI Zhu-liang, WANG Yi-ling, ZHANG Wen-mei   

  1. Department of Orthodontics, Jinan Dental Hospital. Jinan 250001, Shandong Province, China
  • Received:2013-04-03 Online:2014-08-20 Published:2014-10-20

Abstract: PURPOSE:To investigate the effect of premolar extraction on Bolton index overall ratios. METHODS:Bolton index overall ratios were measured in 198 randomly chosen dental casts of three types of Angle’s malocclusions before and after 4 combinations of hypothetical premolar extractions. The data was processed using SPSS 17.0 software package. RESULTS:The overall ratios decreased in each class of Angle’s malocclusion after all combinations of premolars extraction, and the decreases in combinations of 5/5 and 5/4 extractions were significantly greater than that of 4/4 and 4/5 combinations (P<0.05), but no significant difference was found between different types of malocclusion (P>0.05). CONCLUSIONS:When formulating a treatment plan involving premolar extractions, orthodontists should consider that the Bolton overall ratios may decrease.

Key words: Hypothetical tooth extraction, Premolar, Bolton index, Overall ratios

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