Advanced search
Start date


Grant number: 08/06609-9
Support Opportunities:Scholarships in Brazil - Post-Doctoral
Effective date (Start): October 01, 2008
Effective date (End): September 30, 2010
Field of knowledge:Health Sciences - Dentistry - Orthodontics
Principal Investigator:Guilherme dos Reis Pereira Janson
Grantee:Sérgio Estelita Cavalcante Barros
Host Institution: Faculdade de Odontologia de Bauru (FOB). Universidade de São Paulo (USP). Bauru , SP, Brazil


Drill-free insertion of self-drilling screws reduces tooth root damage risk, but increases the peak insertion torque and fracture risk of the mini-implant. The use of larger self-drilling screw diameters improves structural resistance to fracture, however it also increases insertion torque, raising the fracture risk. Considering this antagonistic mini-implant diameter effect on fracture risk, it becomes clinically relevant to evaluate diameter increase efficacy in preventing mini-implant fracture. For this, eight different mini-implant diameters will be evaluated regarding peak resistance torque (fracture torque - FT) and peak insertion torque (PIT), using a digital torquimeter. Initially, 5 mini-implants of each diameter (40 mini-implants) will be inserted into high density bone blocks in order to evaluate the torque intensity able to cause fracture of each mini-implant (FT). Afterwards, 15 mini-implants of each diameter (120 mini-implants) will be inserted into low density polyurethane and bone blocks to evaluate the peak torque required for complete insertion of each mini-implant (PIT). The rate of peak insertion torque regarding fracture torque will be used to determine the fracture risk factor (FRF), expressed by FRF = PIT/FT. The variables FT, PIT and FRF for each diameter will be compared by one-way analysis of variance (ANOVA). Correlations between mini-implant diameter and variables FT, PIT and FRF will be investigated with Pearson's correlation test. The results will be used to determine the mini-implant diameter influence on fracture prevention. This knowledge may influence professional selection as well as the interest of manufacturers for mini-implants with greater structural resistance diameters, associated with smaller insertion torque.

News published in Agência FAPESP Newsletter about the scholarship:
Articles published in other media outlets (0 total):
More itemsLess items

Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
BARROS, SERGIO ESTELITA; JANSON, GUILHERME; CHIQUETO, KELLY; GARIB, DANIELA GAMBA; JANSON, MARCOS. Effect of mini-implant diameter on fracture risk and self-drilling efficacy. AMERICAN JOURNAL OF ORTHODONTICS AND DENTOFACIAL ORTHOPEDICS, v. 140, n. 4, p. E181-E192, . (08/06609-9)

Please report errors in scientific publications list using this form.