Table 2.

Frequency of errors in the mixed and the permanent dentition groups*.

Error	Mixed dentition (%)	Permanent dentition (%)	P
Pt. too far forward	24.5	10.3	0.002**
Pt. too far back	16.8	24.7	0.112
Head twisted	0.7	4.8	0.067
Head tilted	12.6	14.4	0.732
Chin tipped too low	16.1	15.8	1.000
Chin raised too high	22.4	19.2	0.563
Slumped position	2.1	23.3	0.001**
Chin not on chin rest	11.9	47.9	0.001**
Tongue not on plate	60.1	52.7	0.236
Bite guide not used	0	0.7	1.000
Pt. moves	2.1	1.4	0.682
Pt. wears jewelry	5.6	3.4	0.409

*The following errors were excluded since they did not appear in both groups: no home base, use of lead apron which fits intraoral radiographs or thyroid protector, and Cassette resistance.

**Fisher exact test.