Evaluation of Right-Left Symmetry of Condylar Path and Bennett Angles

Determining right-left symmetry of the path of the condyles during eccentric excursions is problematic because direct and indirect measurements have been inconsistent, and clinical methods are complex and time-consuming. Few have studied both the Bennett angles (BA) and condylar path angles (CP). OBJECTIVES: to measure CP and BA with a purportedly simple to use electronic-tracking-device EDT (Cadiax Compact, WaterPik, Co) and to determine the degree of right-left asymmetry of these paths. METHODS: fully dentate faculty, students, and staff were invited to participate. Participants completed a detailed questionnaire (age, gender, dental history) and received a dental examination and temporomandibular joint evaluation. The following were recorded: maximum opening, protrusion, right and left lateral excursions (mm). The ETD was used to measure (3x) the CP and BA during right and left excursions at 3, 5, 10 mm. The raw absolute differences |R-L| and relative differences [|R-L|/|R+L|x100] of the CP and BA were computed. RESULTS: Forty-four individuals (30 males, 14 females), 20-60 years of age, participated. Intraclass correlation coefficients for measurements taken thrice were acceptable; therefore, the computed means were used for analyses. Right-left CP asymmetry was exhibited by 83%; with 50% exhibiting a steeper left CP.  Right-left BA asymmetry was exhibited by 51%; 23% with larger right and 28% larger left BA. Paired t-tests found no significant differences between right and left CP or BA. Table shows measurements at 5 mm.

	Right Side	Left Side	Absolute raw differences |R-L|	Relative differences [|R-L|/|R+L|x100]
Condylar Path Angle (SD)	48.20 (7.10)	49.50 (7.10)	5.20 (4.60)	5.5% (4.9%)
Range	280-600	320-600	00-19.00	0-19.2%
Bennett Angle (SD)	7.90 (3.50)	8.50 (3.90)	3.00 (3.20)	16.2% (16.6%)
Range	50-150	50-150	00-100	0-50%

CONCLUSIONS: The majority of the fully dentate individuals exhibited asymmetrical condylar path angles; however, the mean differences were small, less than 6⁰ for CP and 3⁰ for BA.