title: Interstitial tissue pressure associated with dental injections: a clinical study.
abstract: OBJECTIVE
  The purpose was to measure the interstitial fluid pressure generated from tissue resistance during administration of local anesthetic solution at 4 anatomic locations within the oral cavity and to determine whether differences in soft tissue density affect interstitial fluid pressure when anesthetic solution is administered at a fixed flow rate.
  
  
  METHODS
  A computer-controlled local anesthetic delivery device (CompuFlo, Milestone Scientific) that records and stores pressure data during a subcutaneous injection was used. Subjects consisted of adult patients seeking routine dental care that required local anesthesia. A total of 200 injections were administered and fluid pressure readings recorded. Injections were divided into 4 groups of 50: group 1--intraligamentary injections (PDL); group 2--palatal injection, anterior middle superior alveolar nerve block; group 3--supraperiosteal buccal infiltrations, and group 4--inferior alveolar nerve blocks. For all injections 1 cartridge (1.8 mL) of lidocaine containing 1:100,000 concentration of epinephrine was administered at a fixed flow rate of 0.005 mL/sec.
  
  
  RESULTS
  One-way analysis of variance (ANOVA) revealed that the data were statistically significant (P < .001), with corresponding mean values as follows: group 1, 293.98 psi; group 2, 68.16 psi; group 3, 11.50 psi, and group 4, 9.76 psi (F-ratio of 2371.933). Groups 1 and 2 were different from all other groups; groups 3 and 4 were not statistically different from each other.
  
  
  CONCLUSIONS
  Interstitial resistance to fluid pressure can be measured during administration of 4 different local anesthetic injections used in dentistry. Based on fluid pressure and tissue resistance characteristics, a soft tissue density classification was defined.
authors.affiliation: Department of Orthodontics and Implant Dentistry, New York University College of Dental Surgery, 26 Meadow Woods Road, Lake Success, NY 11020, USA. PerioOrtho@aol.com
authors.forename: Mark N
authors.initials: MN
authors.lastname: Hochman
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Friedman
authors.forename: Wayne
authors.initials: W
authors.lastname: Williams
authors.forename: Claudia B
authors.initials: CB
authors.lastname: Hochman
mesh_terms: D000328:Adult; D000766:Anesthesia, Dental / Q000295:instrumentation*; D000779:Anesthetics, Local / Q000008:administration & dosage*; D002610:Cheek; D004360:Drug Therapy, Computer-Assisted; D045604:Extracellular Fluid / Q000502:physiology*; D006801:Humans; D006874:Hydrostatic Pressure; D007267:Injections / Q000295:instrumentation*; D008012:Lidocaine / Q000008:administration & dosage; D008340:Mandibular Nerve; D008442:Maxillary Nerve; D021362:Palate, Hard; D010513:Periodontal Ligament; D014160:Transducers, Pressure
chemical_list: D000779:Anesthetics, Local; D008012:Lidocaine