title: Comparative study of two needle models in terms of deflection during inferior alveolar nerve block.
abstract: OBJECTIVE
  The purpose of this study is to determine the possible differences in deflection between two needles of same length and external gauge but with different internal gauges during truncal block of the inferior alveolar nerve. The initial working hypothesis was that greater deflection may be expected with larger internal gauge needles.
  
  
  METHODS
  Four clinicians subjected 346 patients to inferior alveolar nerve block and infiltrating anesthesia of the buccal nerve trajectory for the surgical or conventional extraction of the lower third molar. A nonautoaspirating syringe system with 2 types of needle was used: a standard 27-gauge x 35-mm needle with an internal gauge of 0.215 mm or an XL Monoprotect 27-gauge x 35-mm needle with an internal gauge of 0.265 mm. The following information was systematically recorded for each patient: needle type, gender, anesthetic technique (direct or indirect truncal block) and the number of bone contacts during the procedure, the patient-extraction side, the practitioner performing the technique, and blood aspiration (either positive or negative).
  
  
  RESULTS
  346 needles were used in total. 190 were standard needles (27-gauge x 35-mm needle with an internal gauge of 0.215 mm) and 156 were XL Monoprotect. Incidence of deflection was observed in 49.1% of cases (170 needles) where 94 were standard needles and 76 XL Monoprotect. Needle torsion ranged from 0 degrees and 6 degrees.
  
  
  CONCLUSIONS
  No significant differences were recorded in terms of deflection and internal gauge, operator, patient-extraction side, the anesthetic technique involved and the number of bone contacts during the procedure.
authors.affiliation: School of Dentistry of the University of Barcelona, Spain.
authors.forename: Esther
authors.initials: E
authors.lastname: Delgado-Molina
authors.forename: Meritxell
authors.initials: M
authors.lastname: Tamarit-Borras
authors.forename: Leonardo
authors.initials: L
authors.lastname: Berini-Aytés
authors.forename: Cosme
authors.initials: C
authors.lastname: Gay-Escoda
mesh_terms: D004867:Equipment Design; D005260:Female; D006801:Humans; D008297:Male; D008340:Mandibular Nerve; D009339:Needles; D009407:Nerve Block / Q000295:instrumentation*