# Table 3 Hierarchical Poisson regression for impact on OHRQoL of children and independent variables

Variable Impact on child’s OHRQoL Bivariate Multivariate
PR* PR †
p-value p-value
(95% CI) (95% CI)
Sex
Female 132 (32.4) 275 (67.6) 0.864 1.017 (0.836-1.238) - -
Male 139 (31.9) 297 (68.1)   1.00 - -
Age
3 years 71 (25.8) 204 (74.2)   1.00 - -
4 years 95 (28.4) 239 (71.6) 0.470 1.102 (0.847-1.433) - -
5 years 105 (44.9) 129 (55.1) <0.001 1.738 (1.360-2.222) - -
1 st level
Type of preschool
Public 171 (37.5) 285 (62.5) <0.001 1.451 (1.181-1.784) - -
Private 100 (25.8) 287 (74.2)   1.00 - -
Mother’s schooling
≤ 8 years of study 153 (39.4) 235 (60.6) <0.001 1.510 (1.239-1.841) - -
> 8 years of study 118 (26.1) 334 (73.9)   1.00 - -
Monthly household income
≤ 1 minimum salary 177 (40.0) 265 (60.0) <0.001 1.686 (1.357-2.094) - -
> 1 minimum salary 86 (23.8) 276 (76.2)   1.00 - -
Parent’s/guardian’s age
≤ 30 years 139 (32.9) 283 (67.1) 0.456 1.079 (0.883-1.319) - -
> 30 years 123 (30.5) 280 (69.5)   1.00 - -
Number of residents in home
< 6 214 (30.6) 485 (69.4)   1.00 - -
≥ 6 53 (41.1) 76 (58.9) 0.014 1.342 (1.061-1.697) - -
Birth order
Only child 60 (22.8) 203 (77.2)   1.00   1.00
Oldest child 50 (40.7) 73 (59.3) <0.001 1.782 (1.309-2.425) 0.025 1.430 (1.045-1.958)
Middle child 38 (36.5) 66 (63.5) 0.006 1.602 (1.143-2.243) 0.316 1.183 (0.852-1.641)
Youngest child 121 (34.7) 228 (65.3) 0.002 1.520 (1.166-1.981) 0.106 1.228 (0.957-1.575)
2 nd level
Perception of general health
Good 201 (29.6) 479 (70.4)   1.00 - -
Poor 70 (44.0) 89 (56.0) <0.001 1.489 (1.207-1.838) - -
Perception of oral health
Good 120 (21.4) 440 (78.6)   1.00   1.00
Poor 151 (53.5) 131 (46.5) <0.001 2.499 (2.062-3.029) <0.001 1.732 (1.399-2.145)
3 rd level
Dental caries
Absent 46 (16.3) 237 (83.7)   1.00 - -
Present 225 (40.2) 335 (59.8) <0.001 2.472 (1.862-3.281) - -
Cavitated lesions
Absent/white spots 77 (17.5) 364 (82.5)   1.00   1.00
Cavitated anterior teeth 17 (29.3) 41 (70.7) 0.024 1.679 (1.072-2.628) 0.146 1.422 (0.885-2.287)
Cavitated posterior teeth 82 (44.6) 102 (55.4) <0.001 2.552 (1.970-3.307) <0.001 2.011 (1.518-2.664)
Cavitated anterior and posterior teeth 95 (59.4) 65 (40.6) <0.001 3.401 (2.675-4.323) <0.001 2.596 (1.982-3.400)
TDI
Absent 168 (30.4) 385 (69.6)   1.00   1.00
Present 100 (35.0) 186 (65.0) 0.173 1.151 (0.940-1.409) 0.001 1.413 (1.161-1.718)
Type of TDI
Discolouration 38 (39.2) 59 (60.8) 0.071 1.285 (0.979-1.688) - -
Avulsion and/or luxation 4 (36.4) 7 (63.6) 0.661 1.193 (0.542-2.628) - -
Enamel + dentine fracture 16 (38.1) 26 (61.9) 0.276 1.250 (0.836-1.868) - -
Enamel fracture and without trauma 210 (30.5) 479 (69.5)   1.00 - -
Malocclusion
Absent 95 (32.4) 198 (67.6) 0.827 1.023 (0.833-1.258) - -
Present 173 (31.7) 373 (68.3)   1.00 - -
Anterior crossbite
Absent 256 (31.5) 557 (68.5)   1.00 - -
Present 9 (39.1) 14 (60.9) 0.413 1.243 (0.739-2.090) - -
Anterior open bite
Absent 201 (31.1) 446 (68.9)   1.00 - -
Present 58 (32.8) 119 (67.2) 0.663 1.055 (0.830-1.341) - -
Posterior crossbite
Absent 229 (31.3) 503 (68.7)   1.00 - -
Unilateral 30 (32.3) 63 (67.7) 0.848 1.031 (0.754-1.411) - -
Bilateral 5 (55.6) 4 (44.4) 0.058 1.776 (0.980-3.217) - -
Increased overbite
Absent 224 (33.6) 442 (66.4) 0.009 1.518 (1.112-2.073) - -
Present 35 (22.2) 123 (77.8)   1.00 - -
Increased overjet
Absent 144 (30.6) 326 (69.4)   1.00 - -
Present 121 (33.1) 245 (66.9) 0.455 1.079 (0.884-1.317) - -
1. *Unadjusted Poisson regression for independent variables and impact on child’s quality of life.
2. **Variables incorporated in multivariate model (p < 0.20): sex, age, type of preschool, mother’s schooling, monthly household income, number of residents in home, child’s birth order, parent’s/caregiver’s perception of child’s general health, parent’s/caregiver’s perception of child’s oral health, dental caries, untreated dental caries, traumatic dental injury, type of traumatic dental injury, malocclusion, posterior crossbite and increased overbite.
3. ***For dental caries, the cut-off point was code ≥ 2; for cavitated lesions, absent/white spots (codes ≤ 2) and cavitated tooth (codes ≥ 3) were considered.
4. †Hierarchical Poisson regression: Level 1 adjusted for child’s characteristics and socio-demographic variables; Level 2 adjusted for child’s characteristics, socio-demographic variables and parent’s/caregiver’s perception of child’s health; Level 3 adjusted for child’s characteristics, socio-demographic variables, parent’s/caregiver’s perception of child’s health and oral health problems (dental caries, traumatic dental injuries and malocclusion).