A total of 573 subjects (275 dentists and 298 dental assistants) participated in this study. Table 1 shows the personal characteristics of the two groups. A disproportionately higher percentage of dentists (81%) than dental assistants (3%) were male. More than half of the dentists were older than 50 years old, but the majority of assistants were younger than 50 years old. Therefore, the length of practice was significantly longer among the dentists. Among the dental assistants, only one-fourth had health-related backgrounds. There was no significant difference in the working days per week for the two groups. The majority of dentists (60%) treated 11–20 patients every day. Only a small group (4%) saw more than 30 patients per day. In both groups, approximately 20% of the samples were based out of hospitals.
Table 1
Personal characteristics of the included dentists and dental assistants
Characteristics | Dentists | Dental assistants | P-Value |
N = 275 | N = 298 |
| N | % | N | % | |
Gender | | | | | < 0.0001a |
| Male | 222 | 80.73 | 8 | 2.68 | |
| Female | 53 | 19.27 | 290 | 97.32 | |
Age (years) | | | < 0.0001a |
| <=30 | 20 | 7.33 | 94 | 31.76 | |
| 31 ~ 40 | 48 | 17.58 | 118 | 39.86 | |
| 41 ~ 50 | 57 | 20.88 | 61 | 20.61 | |
| 51 ~ 60 | 91 | 33.33 | 15 | 5.07 | |
| >=61 | 57 | 20.88 | 8 | 2.70 | |
Length of practice (years) | | | < 0.0001b |
| Mean, Sd. | 22.49 | , 11.21 | 9.63 | , 7.39 | |
Professional background | | | |
| Health related major | | | 74 | 25.17 | |
| Other majors with professional training | | | 220 | 73.83 | |
Working days per week | 0.054b |
| Mean, Sd. | 5.24 | , 0.68 | 5.13 | , 0.72 | |
Number of patients treated per day | |
| 0 ~ 10 | 52 | 18.98 | | | |
| 11 ~ 20 | 161 | 58.76 | | | |
| 21 ~ 30 | 50 | 18.25 | | | |
| > 30 | 11 | 4.01 | | | |
Setting level | 0.40a |
| Hospital | 55 | 20.00 | 68 | 22.90 | |
| Local dental office | 220 | 80.00 | 229 | 77.10 | |
Sd.: standard deviation |
a Chi-squared test |
b t-test |
Variables with missing values: Age (dentist 2; DA 2); Length of practice (dentist 3; DA 2); Professional background (DA 4); Working days per week (dentist 3; DA 1); Number of patients treated per day (dentist 1); Setting level (DA 1) |
We further compared the personal protection barrier techniques implemented in the two groups (Table 2). We found that the compliance with wearing gloves was high in both groups (95% of dentists and 92% of dental assistants, p = 0.08). Gloves were changed after treating each patient by the majority of dentists (97%) and assistants (95%). However, allergies to protective gloves were more frequent among dental assistants (40%) than among dentists (27%) (p = 0.001). The strategies employed to address the reaction, including consuming allergy medication or changing the type of gloves, were similar for the two groups. It is interesting to see that the hand washing behavior before putting on gloves was similar between dentists (75%) and assistants (76%) (p = 0.65), but assistants were more likely to wash their hands (92%) than dentists (84%) (p = 0.005) after removing gloves.
Table 2
Barrier techniques for infection control among dentists and dental assistants
| Variables | Dentist | Dental assistants | P-Valuea |
| | N = 275 | N = 298 |
| | N | % | N | % | |
Gloves | | | | | 0.08 |
| Yes (yes and optional) | 262 | 95.27 | 273 | 91.61 | |
| No | 13 | 4.73 | 25 | 8.39 | |
Frequency of changing gloves | | | | | 0.29 |
| Every patient | 263 | 96.69 | 280 | 94.92 | |
| More than one patient | 9 | 3.31 | 15 | 5.08 | |
Glove allergy | | | 0.001 |
| Yes | 74 | 26.81 | 118 | 39.6 | |
| No | 201 | 73.19 | 180 | 60.4 | |
Has allergies and takes medical treatment | | | | 0.78 |
| No | 47 | 65.28 | 74 | 63.25 | |
| Yes | 25 | 34.72 | 43 | 36.75 | |
Has allergies and changes to different gloves | | | | 0.77 |
| No | 22 | 31.88 | 34 | 29.82 | |
| Yes | 47 | 68.12 | 80 | 70.18 | |
Changes type of gloves | | | | | 0.27 |
| Did not change | 22 | 31.88 | 34 | 29.82 | |
| Latex with powder | 8 | 11.59 | 24 | 21.05 | |
| Latex without powder | 30 | 43.48 | 48 | 42.11 | |
| Non-latex | 9 | 13.04 | 8 | 7.02 | |
Washes hands before putting on gloves | | | | | 0.65 |
| Yes | 205 | 74.55 | 227 | 76.17 | |
| No | 70 | 24.45 | 71 | 23.83 | |
Washes hands after removing gloves | | | | | 0.005 |
| Yes | 231 | 84.31 | 274 | 91.95 | |
| No | 43 | 15.69 | 24 | 8.05 | |
Oral masks | | | | 0.07 |
| Yes | 272 | 98.91 | 288 | 96.64 | |
| No | 3 | 1.09 | 10 | 3.36 | |
Hair caps | | | 0.011 |
| Yes | 57 | 20.73 | 37 | 12.42 | |
| Optional | 109 | 39.64 | 114 | 38.26 | |
| No | 109 | 39.64 | 147 | 49.33 | |
Facial mask | | | | | < 0.0001 |
| Yes | 99 | 36.00 | 37 | 12.42 | |
| Optional | 134 | 48.73 | 121 | 40.60 | |
| No | 42 | 15.27 | 140 | 46.98 | |
Work attire | | | | | 0.027 |
| Casual clothes | 10 | 3.64 | 12 | 4.15 | |
| Work clothes | 184 | 66.91 | 220 | 76.12 | |
| Scrubs | 81 | 29.45 | 57 | 19.72 | |
a Chi-squared test |
Variables with missing values: Frequency of changing gloves (dentist 3; DA 3); Has allergies and takes medical treatment (dentist 2; DA 1); Has allergies and changes to different gloves (dentist 5; DA 4); Work attire (dentist 0; DA 9); Washes hand after removing gloves (dentist 1; DA 0) |
As far as other personal protection means, we found that compliance with wearing oral masks was very high in Taiwan for both groups (99% in dentists and 97% in dental assistants). However, the behavior of wearing hair caps, goggles, and other protective attire was different between dentists and dental assistants. A higher proportion of dentists (60.3%) wore hair caps (p = 0.011) and facial masks (goggles) (p < 0.0001) than assistants (50.7%). Dental assistants were more likely (76%) than dentists (67%) to wear uniform gowns but less likely to wear protective gowns (29% for dentists and 20% for assistants) (p = 0.027).
The behavior of disinfection and sterilization for infection control was similar in dentists and dental assistants (Table 3). Compliance with the use of autoclaves for sterilizing general dental instruments, extraction instruments, and hand pieces was excellent in Taiwan for both dentists and dental assistants. Dental assistants (78%) were more likely than dentists (73%) to autoclave dental burs (p = 0.014). Approximately 80% (453/574) of the participants used chemical indicators during sterilization. The most frequent disinfectant was glutaraldehyde. Seventy-five percent of dentists and 81% of dental assistants conducted surface disinfection of working tables. For impression materials, approximately 70% used water for disinfection.
Table 3
Disinfection and sterilization for infection control among dentists and dental assistants
| Variables | Dentist | Dental Assistants N = 298 | P-Valuea |
| | N = 275 | |
| | N | % | N | % | |
General dental instrument disinfection | | | | 0.056 |
| Autoclave | 246 | 93.89 | 267 | 92.39 | |
| Chemicals | 3 | 1.15 | 12 | 4.17 | |
| Other | 13 | 4.96 | 9 | 3.13 | |
Extraction instrument disinfection | | | | | 0.24 |
| Autoclave | 263 | 97.41 | 280 | 95.56 | |
| Other | 7 | 2.59 | 13 | 4.44 | |
Handpiece disinfection | | | | | 0.52 |
| Autoclave | 231 | 86.19 | 255 | 87.63 | |
| Chemicals | 11 | 4.10 | 7 | 2.41 | |
| Other | 26 | 9.70 | 29 | 9.97 | |
Bur disinfection | | | | 0.014 |
| Autoclave | 199 | 73.43 | 229 | 77.89 | |
| Chemicals | 50 | 18.45 | 58 | 19.73 | |
| Other | 22 | 8.12 | 7 | 2.38 | |
Chemical indicator use during sterilization | | | 0.37 |
| Yes | 213 | 77.45 | 240 | 80.54 | |
| No | 62 | 22.55 | 58 | 19.46 | |
Disinfectant | | | | 0.20 |
| Glutaraldehyde | 156 | 65.27 | 135 | 59.73 | |
| Phenol & NaOCl | 38 | 15.90 | 34 | 15.04 | |
| Alcohol | 12 | 5.02 | 9 | 3.98 | |
| Others | 33 | 13.81 | 48 | 21.24 | |
Surface disinfection of working tables | | | | 0.09 |
| Yes | 207 | 75.27 | 241 | 81.14 | |
| No | 68 | 24.73 | 56 | 18.86 | |
Disinfection of impression materials | | | 0.36 |
| Disinfectant | 84 | 30.66 | 81 | 27.18 | |
| Water | 190 | 69.34 | 217 | 72.82 | |
a Chi-squared test |
Variables with missing values: General dental instrument disinfection (dentist 13; DA 10); Extraction instrument disinfection (dentist 5; DA 5); Handpiece disinfection (dentist 7; DA 7); Bur disinfection (dentist 4; DA 4); Disinfectants (dentist 36; DA 72); Surface disinfection of working tables (dentist 0; DA 1); Disinfection of impression materials (dentist 1; DA 0) |
Factors associated with personal protection behavior, such as wearing hair caps and facial masks and hand washing, were identified using multivariable logistic regression. The full model is presented in Table 4. The reduced model is presented in Table 5. For wearing hair caps, we found that setting level was a significant factor for both dentists (aOR = 3.10, 95% CI: 1.38–6.96) and dental assistants (aOR = 2.33, 95% CI: 1.10–4.96). Using disinfectants for impression materials was also positively associated with hair cap wearing (aOR = 2.03 for dentists (95% CI: 1.04–3.95) and 3.55 for dental assistants (95% CI: 1.79–7.02)). Surface disinfection of working tables was also a significant factor for hair cap wearing for assistants (aOR = 3.00, 95% CI: 1.35–6.65) but not for dentists.
Table 4
Factors associated with hair cap, facial mask wearing and hand washing by multivariable (full model)
Variables | Hair Cap | | Facial Mask | | Hand washings |
Dentist | Dental Assistant | | Dentist | Dental Assistant | | Dentist | Dental Assistant |
| OR (95%CI) | OR (95%CI) | | OR (95%CI) | OR (95%CI) | | OR (95%CI) | OR (95%CI) |
Gender | | | | | | | | |
Female | | | | 1.00 | | | | |
Male | | | | 0.22* (0.05–0.99) | | | | |
Length of practice | | | | | | | | |
years | | | | | 1.05** (1.01–1.09) | | | 1.06* (1.01–1.10) |
Setting level | | | | | | | | |
Local dental office | 1.00 | 1.00 | | | 1.00 | | | |
Hospital | 2.86** (1.37–5.97) | 2.53** (1.28–4.99) | | | 2.03* (1.07–3.84) | | | |
Frequency of changing gloves | | | | | | | | |
More than one patient | | | | | 1.00 | | | 1.00 |
Every patient | | | | | 6.71* (1.35–33.28) | | | 5.61** (1.59–19.81) |
Bur disinfection | | | | | | | | |
Chemical | | 1.00 | | | | | | |
Autoclave | | 2.28* (1.12–4.67) | | | | | | |
Chemical indicator use during sterilization | | | | | | | | |
No | | | | 1.00 | | | 1.00 | |
Yes | | | | 3.38** (1.53–7.46) | | | 1.95* (1.04–3.62) | |
Surface disinfection of working tables | | | | | | | | |
No | | 1.00 | | | | | | 1.00 |
Yes | | 2.48* (1.23-5.00) | | | | | | 2.98** (1.52–5.85) |
Disinfection of impression materials | | | | | | | | |
Water | 1.00 | 1.00 | | 1.00 | 1.00 | | 1.00 | 1.00 |
Disinfectant | 2.16* (1.19–3.93) | 3.64** (1.90–6.95) | | 3.47* (1.15–10.46) | 2.17* (1.18-4.00) | | 2.05* (1.09–3.87) | 2.43* (1.10–5.34) |
*P < 0.05 |
**P < 0.01 |
Backward selection with P < 0.05 |
Table 5
Factors associated with hair cap, facial mask wearing and hand washing by multivariable (reduced model)
Variables | Hair Cap | | Facial Mask | | Hand washing |
Dentist | Dental Assistant | | Dentist | Dental Assistant | | Dentist | Dental Assistant |
| OR (95%CI) | OR (95%CI) | | OR (95%CI) | OR (95%CI) | | OR (95%CI) | OR (95%CI) |
Gender | | | | | | | | |
Female | 1.00 | − | | 1.00 | − | | 1.00 | − |
Male | 0.93 (0.42–2.03) | − | | 0.15* (0.02–0.98) | − | | 0.65 (0.30–1.41) | − |
Age | | | | | | | | |
Dentist | Dental Assistant | | | | | | | | |
≤ 40 | ≤ 30 | 1.00 | 1.00 | | 1.00 | 1.00 | | 1.00 | 1.00 |
41 ~ 50 | 31 ~ 40 | 1.14 (0.36–3.62) | 0.84 (0.42–1.66) | | 0.42 (0.06-3.00) | 0.94 (0.49–1.80) | | 1.49 (0.45–4.92) | 0.83 (0.39–1.74) |
51 ~ 60 | ≥ 41 | 0.36 (0.08–1.57) | 1.31 (0.55–3.17) | | 0.17 (0.01–1.92) | 1.19 (0.50–2.83) | | 0.90 (0.19–4.21) | 1.21 (0.42–3.46) |
≥ 61 | | 0.73 (0.10–5.09) | | | 0.27 (0.01–6.43) | | | 2.61 (0.33–20.89) | |
Length of practice | | | | | | | | |
years | 1.01 (0.95–1.08) | 1.01 (0.97–1.06) | | 1.06 (0.96–1.17) | 1.05* (1.00-1.10) | | 1.00 (0.93–1.06) | 1.05 (0.99–1.11) |
Working days per week | | | | | | | | |
> 5 days | 1.00 | 1.00 | | 1.00 | 1.00 | | 1.00 | 1.00 |
≤ 5 days | 1.59 (0.87–2.91) | 1.77† (0.95–3.27) | | 1.00 (0.41–2.45) | 1.82* (1.01–3.30) | | 1.39 (0.77–2.52) | 1.17 (0.59–2.32) |
Setting level | | | | | | | | |
Local dental office | 1.00 | 1.00 | | 1.00 | 1.00 | | 1.00 | 1.00 |
Hospital | 3.10** (1.38–6.96) | 2.33* (1.10–4.96) | | 2.96 (0.61–14.35) | 1.58 (0.78–3.20) | | 1.29 (0.59–2.85) | 1.23 (0.52–2.86) |
Number of patients treated per day | | | | | | | | |
0 ~ 10 | 1.00 | − | | 1.00 | − | | 1.00 | − |
11 ~ 20 | 1.36 (0.63–2.94) | − | | 1.56 (0.53–4.53) | − | | 1.74 (0.83–3.65) | − |
> 20 | 1.63 (0.66–4.05) | − | | 1.56 (0.42–5.78) | − | | 1.40 (0.59–3.33) | − |
Professional background | | | | | | | | |
Other majors | − | 1.00 | | − | 1.00 | | − | 1.00 |
Health related major | − | 1.42 (0.71–2.83) | | − | 1.52 (0.79–2.95) | | − | 1.15 (0.52–2.55) |
General dental instrument disinfection | | | | | | | | |
Chemicals | 1.00 | 1.00 | | 1.00 | 1.00 | | − | 1.00 |
Autoclave | 0.61 (0.02–17.31) | 5.45 (0.60–49.10) | | 2.71 (0.07-101.24) | 0.67 (0.16–2.80) | | − | 2.85 (0.55–17.74) |
Extraction instrument disinfection | | | | | | | | |
Not autoclave | 1.00 | 1.00 | | − | 1.00 | | 1.00 | 1.00 |
Autoclave | 0.33 (0.02–5.53) | 1.12 (0.22–5.55) | | − | 2.08 (0.47–9.19) | | 4.87 (0.70-34.01) | 0.54 (0.09–3.45) |
Handpiece disinfection | | | | | | | | |
Chemicals | 1.00 | 1.00 | | 1.00 | 1.00 | | 1.00 | 1.00 |
Autoclave | 1.10 (0.24–5.01) | 0.35 (0.05–2.39) | | 0.91 (0.11–7.28) | 1.79 (0.17–18.72) | | 0.55 (0.10–3.17) | 0.91 (0.11–7.33) |
Bur disinfection | | | | | | | | |
Chemicals | 1.00 | 1.00 | | 1.00 | 1.00 | | 1.00 | 1.00 |
Autoclave | 0.58 (0.26–1.32) | 2.09† (0.87–5.03) | | 1.89 (0.66–5.42) | 1.33 (0.59-3.00) | | 0.47† (0.20–1.10) | 0.52 (0.19–1.40) |
Chemical indicator use during sterilization | | | | | | | | |
No | 1.00 | 1.00 | | 1.00 | 1.00 | | 1.00 | 1.00 |
Yes | 1.01 (0.46–2.07) | 1.24 (0.59–2.63) | | 2.94* (1.19–7.24) | 0.97 (0.47–1.98) | | 2.36* (1.17–4.75) | 1.96† (0.93–4.16) |
Surface disinfection of working tables | | | | | | | | |
No | 1.00 | 1.00 | | 1.00 | 1.00 | | 1.00 | 1.00 |
Yes | 1.94† (0.99–3.84) | 3.00** (1.35–6.65) | | 1.34 (0.53–3.39) | 2.05† (0.99–4.25) | | 1.31 (0.67–2.56) | 2.76** (1.29–5.90) |
Disinfection of impression materials | | | | | | | | |
Water | 1.00 | 1.00 | | 1.00 | 1.00 | | 1.00 | 1.00 |
Disinfectant | 2.03* (1.04–3.95) | 3.55** (1.79–7.02) | | 3.03† (0.91–10.14) | 2.40** (1.25–4.61) | | 2.24* (1.11–4.53) | 2.25† (0.97–5.25) |
Gloves | | | | | | | | |
No | 1.00 | 1.00 | | 1.00 | 1.00 | | 1.00 | 1.00 |
Yes | 3.45 (0.62–19.27) | 0.56 (0.16–1.92) | | 1.66 (0.28–9.67) | 0.94 (0.28–3.17) | | 0.41 (0.09–1.84) | 0.59 (0.13–2.65) |
Frequency of changing gloves | | | | | | | | |
More than one patient | 1.00 | 1.00 | | 1.00 | 1.00 | | − | 1.00 |
Every patient | 0.77 (0.11–5.39) | 1.57 (0.38–6.54) | | 3.06 (0.37–25.27) | 8.04* (1.39–46.47) | | − | 5.96* (1.39–25.51) |
Oral masks | | | | | | | | |
No | 1.00 | 1.00 | | − | 1.00 | | 1.00 | 1.00 |
Yes | 5.07 (0.39–66.17) | 0.55 (0.09–3.48) | | − | 1.78 (0.30–10.50) | | 8.67 (0.62-120.63) | 1.62 (0.21–12.39) |
†P < 0.10 |
*P < 0.05 |
**P < 0.01 |
Factors related to facial masks were different between dentists and assistants. Gender (male; aOR = 0.15 (95% CI: 0.02–0.98)) and chemical indicator use during sterilization (aOR = 2.94, 95% CI: 1.19–7.24) were significant factors for dentists. For assistants, a longer working experience (aOR = 1.05 (95% CI: 1.00-1.10) per year longer), fewer working days per week (aOR = 1.82, 95% CI: 1.01–3.30), the use of disinfectants for impression materials (aOR = 2.40, 95% CI: 1.25–3.30), and the frequent use of gloves (aOR = 8.04, 95% CI; 1.39–46.47) were positively associated with wearing facial masks. The use of chemical indicators during sterilization (aOR = 2.36, 95% CI; 1.17–4.75) and disinfectants for impression materials (aOR = 2.24, 95% CI; 1.11–4.53) were associated with hand washing for dentists, whereas surface disinfection of working tables (aOR = 2.76, 95% CI; 1.29–5.90) and frequent changing of gloves (aOR = 5.96, 95% CI; 1.39–25.51) were associated with hand washing for assistants.
The results of multivariable logistic regression with backward selection are shown in Table 5. The use of disinfectants for impression materials was consistently positively associated with the three personal protection behaviors for both dentists and assistants. The others remain similar as in the full model. However, the frequency of changing gloves became insignificant.