title: Comparing condylar positions achieved through bimanual manipulation to condylar positions achieved through masticatory muscle contraction against an anterior deprogrammer: a pilot study.
abstract: BACKGROUND
  The condylar position can vary depending on several factors. One factor is the influence of occluding teeth. If the influence from occluding teeth could be eliminated, it might be possible to evaluate the condylar position obtained from masticatory muscle contraction.
  
  
  OBJECTIVE
  The purpose of this pilot study was to determine the placement of the condyles by contracted masticatory muscles without influence from occluding teeth.
  
  
  METHODS
  For a group of 11 participants, 3 dentists were assigned, in turn, to fabricate a centric relation interocclusal record using bimanual manipulation on each member of the group. After obtaining the centric relation interocclusal records using bimanual manipulation, the records were stored in room temperature water. Subsequently, each of the 11 patients had an anterior deprogrammer fabricated and were given instructions to wear the anterior deprogrammer for 60 minutes. The anterior deprogrammer was designed with the contacting surface perpendicular to the arc of close of the mandibular incisors. In addition, the anterior deprogrammer was relined to eliminate any movement under force, and the occluding surface of the deprogrammer was free of any indentations. After wearing the deprogrammer, 4 interocclusal records (3 in a reclined position and 1 in an upright position to ensure the condylar position did not change in the upright position) were made by having the patient squeeze and close into a properly adapted, trimmed, and warmed interocclusal record. The condylar position in centric relation recorded in interocclusal records using bimanual manipulation was compared to the condylar position recorded by the contraction of the masticatory muscles against an anterior deprogrammer using a condylar position indicating device. The data were analyzed with a 2-independent-samples test of proportions, alpha=.05 (1-tail).
  
  
  RESULTS
  The condylar positions obtained using bimanual manipulation repeated the condylar position within the 0.11-mm tolerance of the Centri-Check instrument in 33 out of 33 opportunities (100%). The condylar positions obtained by using the anterior deprogrammer technique repeated the condylar position within the 0.11-mm tolerance of the Centri-Check in 43/44 opportunities (97.7%). The sample size used in this pilot study was not large enough to detect a very small actual difference (5 percentage points or less) between the 2 methods, should such a difference exist.
  
  
  CONCLUSIONS
  The results of this pilot study indicate that, without influence from occluding teeth, the contraction of the masticatory muscles places the condyles into the same position as centric relation.
authors.affiliation: jlpcm@aol.com
authors.forename: James R
authors.initials: JR
authors.lastname: McKee
mesh_terms: D016302:Centric Relation; D003725:Dental Articulators; D003766:Dental Occlusion; D006801:Humans; D007180:Incisor / Q000033:anatomy & histology; D007574:Jaw Relation Record / Q000379:methods; D008335:Mandibular Condyle / Q000033:anatomy & histology*; D008410:Masticatory Muscles / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology*; D017090:Occlusal Splints; D010865:Pilot Projects; D013499:Surface Properties; D013997:Time Factors