title: Evaluation of bone heating, immediate bone cell viability, and wear of high-resistance drills after the creation of implant osteotomies in rabbit tibias.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the influence of reusing high-resistance drills on bone heating, immediate bone cell viability, and drill wear after performing implant osteotomies in rabbit tibias.
  
  
  METHODS
  Two hundred sequential implant osteotomies were created in the superior tibial cortex of 12 White male rabbits. Six groups were established (G1 to G6) according to the number of osteotomies performed with each drill (0, 10, 20, 30, 40, and 50). Drilling began with a spear drill, followed by 2.0-mm, 2.8-mm, 3.0-mm, and 3.15-mm helical drills. The receptor beds were collected for immunohistochemical analysis, thermal changes were quantified, and the drills were subjected to scanning electron microscopy analysis.
  
  
  RESULTS
  A high degree of correlation between drill wear and number of osteotomies was observed (Pearson correlation coefficient, r = 0.984). Spear drills underwent twice as much deformation as helical drills. The bone heating analysis concluded that there was no statistically significant relationship between the number of osteotomies and bone heating (P > .05), but there were greater thermal changes during drilling with the spear drill than during drilling with helical drills (ratio 3:1). Immunohistochemical analysis showed a physiologic balance of osteoprotegerin and RANKL (receptor activator of nuclear factor κB ligand) immunolabeling in all groups; however, there was greater immunolabeling of all proteins in group G6 (50 osteotomies).
  
  
  CONCLUSIONS
  The tested drills did not cause significant bone heating after being reused 50 times; however, they caused more tissue trauma in the 50th osteotomy. Worn drills that are reused may be expected to cause excessive damage to the bone tissue and could adversely affect the osseointegration process.
authors.affiliation: Universidade Estadual Paulista, Araçatuba Dental School, Brazil. abrahao_cav@yahoo.com.br
authors.forename: Abrahão Cavalcante Gomes de Souza
authors.initials: AC
authors.lastname: Carvalho
authors.forename: Thallita Pereira
authors.initials: TP
authors.lastname: Queiroz
authors.forename: Roberto
authors.initials: R
authors.lastname: Okamoto
authors.forename: Rogerio
authors.initials: R
authors.lastname: Margonar
authors.forename: Idelmo Rangel
authors.initials: IR
authors.lastname: Garcia
authors.forename: Osvaldo
authors.initials: O
authors.lastname: Magro Filho
mesh_terms: D000818:Animals; D002470:Cell Survival; D003758:Dental Implantation, Endosseous / Q000009:adverse effects / Q000295:instrumentation*; D017743:Equipment Reuse; D006358:Hot Temperature / Q000009:adverse effects; D008297:Male; D016348:Osseointegration / Q000502:physiology*; D010027:Osteotomy / Q000009:adverse effects / Q000295:instrumentation*; D011817:Rabbits; D018709:Statistics, Nonparametric; D013499:Surface Properties; D013977:Tibia / Q000502:physiology / Q000601:surgery* / Q000648:ultrastructure; D014945:Wound Healing / Q000502:physiology