Accuracy of the Occlusal Plane When Mounting in Semi-Adjustable Articulator

Objectives: The purpose of this study was to determine by radiographic evaluation, the accuracy in which two semiadjustable articulators, Whip-Mix (Whip-Mix Corp. Louisville, Kentucky) and Denar Mark II (Denar Corp. Anaheim, California), reproduced maxillary position regarding Frankfort's referential horizontal plane. Methods: Twenty-eight young adult subjects with healthy and complete dentition were selected. A cephalogram and casts of the maxillary arch were obtained, as well as the face bow transfers. The casts were mounted on its articulator according to procedures and one lateral radiograph was gotten on each one of them. The cephalometric drawings from the occlusal plane and from the Frankfort horizontal plane were done in each cephalogram and lateral radiograph of mounted casts. Data were tabulated and a t Student test for paired data was applied to determine whether the differences between the measured angles in both articulators. Results: Significant differences in groups were seen (p<.01) in the angular measures of the devices regarding to measures registered by the cephalometries. Table 1 shows descriptive statistic and Table 2 shows results from t Student test. Graphic 1 shows differences between angles from the radiographs of each articulator in regard to angle from each patient's cephalograph. Conclusion: Therefore it can be concluded that the transferred model to studied articulators showed variations with regard to Frankfort Plane with the studied face bow-articulator systems

TABLE 1. Descriptive statistics for values from angles between Frankfort and occlusal plane in each radiograph. Values in degrees.

	n	Mean	S.D.	Min	Max	S.E.
Cefalograph	28	13.35	4.06	6.25	21.75	0.77
Whip – Mix	28	12.84	4.59	6	24	0.87
Denar Mark II	28	13.99	4.48	6	23.75	0.85

S.D. : Standard Deviation (√s² )

S.E. : Standard Error ( s / √n )

TABLE 2. Results of t Student test for paired differences.

Diference	n	xD	SD / √n	tc	p
Whip-Mix vs. Cefalograph	28	3.17	0.43	7.349	**
Denar vs. Cefalograph	28	2.36	0.47	6.098	**

** p < 0.05