TABLE 1.

Baseline Characteristics of the Participants by Removal Status at Follow-Up: Northwest Practice-based REsearch Collaborative in Evidence-based DENTistry, Pacific Northwest, 2009–2012

Characteristic	Total (n = 801), % or Mean (SD)	Third Molar Removal Status at Follow-Up,a % or Mean (SD)
		Third Molar Removal (≥ 1; n = 201)	Third Molar Retention (All Existing; n = 316)
Gender
Female	49	51	51
Male	51	49	49
Age, y
16	24	28	23
17	23	23	20
18	21	20	21
19	12	12	13
20	9	7	11
21–22	11	9	13
Raceb
White	90	92	91
Other	8	7	8
Dental insurance
No insurance	10	12	9
Medicaid	11	6	7
Private insurance	79	82	84
Frequency of dental cleanings
≥ 2/y	65	72	67
1/y	23	22	23
< 1/y	12	7	9
Current smoking
No	94	95	97
Yes	6	6	3
Eruption status of third molars
None visible in mouth	70	72	70
≥ 1 visible	30	29	30
Angulation (highest in patient)
≤ 35°	51	45	53
> 35°	49	55	47
Pain or discomfort around third molarsc
No	85	82	90
Yes	15	19	10
Dental caries at distal of second molar
No	94	96	96
Yes	6	4	4
Dental caries on third molars
No	92	94	92
Yes	8	6	8
Paresthesia
No	99.6	99	99.7
Yes	0.4	1	0.3
Pericoronitis
No	94	94	95
Yes	6	7	5
TMD signs and symptoms (categories not exclusive)
None	64	63	62
Popping or clicking	27	27	29
Jaw pain on wide opening	13	13	9
Pain in temples, jaw joint, or jaw muscles	17	20	16
Maximum pocket depth at distal of second molarc
< 4 mm	41	31	50
≥ 4 mm	59	69	50
Attachment loss at distal of second molar, mm	0.75 (1.09)	0.82 (1.11)	0.57 (0.90)

Note. TMD = temporomandibular joint disorder.

^a284 participants were lost to follow-up, and third molar removal status is unknown.

^b14 participants did not report race.

^cP < .05 between removal and retention group from bivariate generalized estimating equations logistic regression.