Possible causal relationships between competitive swimming in growing age and three-dimensional dentoalveolar development

Progress in Orthodontics

Table 3 Upper and lower dental arch dimensions, according to the appropriate templates based on the Ricketts pentamorphic arches, and dental crowding

Variable	Swimmers	Non-swimmers	P(chi squared)
Upper arch dimensions (%)
−15	0	0	NS
−10	4	4	NS
−5	6	24	0.001
0	36	42	NS
5	0	0	NS
10	45	27	0.001
15	9	3	NS
Upper arch crowding (mm)
>−3.5	2	15	0.001
−3.0 to −0.5	49	41	NS
0	35	30	NS
0.5 to 3.0	12	14	NS
>3.5	2	0	NS
Lower arch dimensions (%)
−15	0	0	NS
−10	4	4	NS
−5	7	24	0.001
0	37	41	NS
5	0	0	NS
10	43	27	0.01
15	9	3	0.048
Lower arch crowding (mm)
>−3.5	8	22	0.005
−3.0 to −0.5	54	53	NS
0	27	18	NS
0.5 to 3.0	11	7	NS
>3.5	0	0	NS

Negative, reduced dimensions/lack of space; positive, increased dimensions/excess of space.
NS, not significantly different.