title: Ex vivo study of manual and rotary instrumentation techniques in human primary teeth.
abstract: OBJECTIVE
  This study aimed to evaluate, ex vivo, time and dentin removal by manual and rotary instrumentation in human primary teeth.
  
  
  METHODS
  Eighty primary teeth were divided into 2 groups, embedded in resin, and sectioned for evaluation before and after instrumentation. For manual technique, teeth were prepared using K-type files and rotary preparation was performed with Hero 642. All root canals were prepared up to size 40, and the instrumentation time was recorded. Dentin removal was calculated using digital image software. Data was statistically analyzed using chi-squared, Mann-Whitney, and t tests.
  
  
  RESULTS
  Manual instrumentation removed more dentin in all groups compared with rotary instrumentation (P < .05). In some specimens, root perforations were observed in areas coinciding with largest root resorption. Rotary technique showed the shortest instrumentation time (P < .05).
  
  
  CONCLUSIONS
  Deciduous teeth, without significant root resorption, have enough root structure for instrumentation up to size 40. Rotary technique required less time and generated less dentin removal.
authors.affiliation: Brazil School of Dentistry, Federal University of Santa Catarina, Florianópolis, Santa Catarina. thaisreginakummer@gmail.com
authors.forename: Thais Regina
authors.initials: TR
authors.lastname: Kummer
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Calvo
authors.forename: Mabel Mariela Rodríguez
authors.initials: MM
authors.lastname: Cordeiro
authors.forename: Ricardo
authors.initials: R
authors.lastname: de Sousa Vieira
authors.forename: Maria José
authors.initials: MJ
authors.lastname: de Carvalho Rocha
mesh_terms: D016009:Chi-Square Distribution; D003786:Dental Pulp Cavity / Q000033:anatomy & histology / Q000601:surgery; D003804:Dentin / Q000601:surgery*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D018915:Root Canal Preparation / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods; D012399:Rotation; D018709:Statistics, Nonparametric; D013997:Time Factors; D014094:Tooth, Deciduous / Q000601:surgery*