Attitudes towards and use of dental dams by final-year dental students in Chongqing, China: a cross-sectional study.

OBJECTIVES: To investigate the current and intended future use of dental dams (DDs) and attitudes regarding DD use among final-year dental students at two levels (undergraduate and college) in dental schools in Chongqing, China.
DESIGN: A cross-sectional study based on a questionnaire was conducted from June to July 2021.
SETTING: Chongqing Medical University (CQMU, undergraduate level) and Chongqing Three Gorges Medical College (CQTGMC, junior college level). PARTICIPANTS: A total of 245 final-year dental students. MAIN OUTCOME MEASURES: An anonymous online questionnaire was distributed to dental students less than 1 month before graduation. Students were asked about the DD training they had received, their attitudes towards some aspects of DDs, their current DD use and their intended future DD use in adult or child patients and in various dental procedures.
RESULTS: A total of 238 valid questionnaires were returned (response rate=97.1%, CQMU=96.2%, n=76; CQTGMC=97.6%, n=162). A total of 47.5% of respondents used DDs on real patients during their internships (CQMU=59.2%, CQTGMC=42.0%, p<0.05). Whether in restorative procedures or endodontic treatment, the most common reason for not using DDs was a 'lack of knowledge and experience', followed by 'DDs could not be provided by internship institutions'. Although the advantages of DDs were recognised by most students from the two schools, 52.9% thought DDs were difficult to apply (CQMU=42.1%, CQTGMC=58.0%, p<0.05). A total of 92.1% of CQMU respondents and 95.1% of CQTGMC respondents expressed their willingness to use DDs after independent practice in the future.
CONCLUSIONS: Although final-year students have a clear awareness of the advantages of DDs and are very enthusiastic about future DD use, the current DD utilisation rate is low. Education about DDs should be continuously improved in many aspects, and the advantages of using DDs in clinical dentistry should be further emphasised at dental schools. © Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.

This was a cross-sectional study and was one of the few studies concerning the use of and attitudes towards dental dams by Chinese dental interns.

Our study selected school students as subjects and investigated them with an anonymous questionnaire, which ensured the authenticity of the results to a certain extent.

Some results may be biased because data points come from self-report questionnaires rather than direct observation of students’ learning and clinical operations.

Interns may share attitudes and views, and this tendency for consensus may bias the survey results.

Introduction

Dental dams (DDs) have long been considered an established adjunct in operative dentistry procedures and endodontic treatment. They have been used for more than 100 years to control the oral environment.1 DDs can isolate teeth from any obstacles, such as saliva, tongue, and buccal mucosa, that may interfere with an operation, thus creating a separate, surgically clean operating field and reducing the risk of potential infection transfer.2 Moreover, the risk of swallowing or inhaling instruments and medicaments is minimised, and clinical dentists are protected from prosecution due to the patient swallowing or inhaling something during a procedure.3 Improved patient comfort is another advantage of DDs. Previous studies have shown that patients generally have a positive attitude towards DD experiences.4 5 In view of the above advantages, many authorities recommend that DDs be routinely used to isolate teeth undergoing endodontic treatment.6–8

In recent years, the application of DD technology has become increasingly widespread, but the prevalence of DD use in various countries is still uneven. According to a survey on the use of DDs by general dentists in the USA, 58% of respondents indicated that they always use the technology.9 Another study from the USA surveyed 1490 general practitioners, 47% of whom reported that they always used DDs in root canal treatment.10 A total of 1085 Indian endodontists were investigated by Kohli et al.11 The results showed that the use rate of DDs was 50.5%. Additionally, Raoof et al12 found that the DD usage rate in root canal treatment among general dental practitioners in Iran was 16.5%.

There are many factors leading to the underuse of DDs among dental practitioners, including patient refusal, high cost, time consumption and difficulty in application.1 13 14 Another important reason for the suboptimal use of DDs is that dentists do not receive systematic education and professional training regarding DDs.1 14 15 The primary task of contemporary dental education is to train dentists who can implement safe and high-quality treatment.16 Before working independently, dental students should master the use of DDs and establish that DD use is safe and offers the ability to provide high-quality service. These advantages are of great help in cultivating good clinical diagnosis and treatment habits and improving the utilisation rate of DDs in future clinical work.

However, there is a lack of investigation of the use of DDs by Chinese dental students. Since dental students are future dentists, investigating their use and attitudes towards DDs in schools will help identify potential problems related to the implementation of this world-renowned method and further predict general practice trends in this field.2 This approach has been considered in similar studies many times.2 16–19

The purpose of this study is to investigate students’ current use of DDs, their attitudes towards DDs, and their intended future use of DDs among final-year dental students at two levels (undergraduate level and junior college level) in dental schools in Chongqing, China.

Materials and methods

This cross-sectional study, based on a questionnaire survey, was conducted in Chongqing, China, from June to July 2021. In Chongqing, only Chongqing Medical University (CQMU) and Chongqing Three Gorges Medical College (CQTGMC) have stomatology as a major and have trained graduates. The stomatology major of CQMU is at the undergraduate level (5-year degree programme), while that of CQTGMC is at the junior college level (3-year degree programme). In the first 4 (CQMU) or 2 years (CQTGMC), students receive theoretical teaching and laboratory simulation practice in the school, and in the last year, they receive clinical training in an internship institution. Our study investigated final-year dental students who graduated from these two schools in 2021. The complete list of classes was obtained from these schools. There were 79 students from CQMU and 166 from CQTGMC. Participation in the survey was voluntary, and all students had the opportunity to refuse participation when the questionnaire was distributed.

The survey was administered as an anonymous network questionnaire. First, we extensively reviewed the literature2 16–25 on the questionnaire survey of the clinical use of DDs and dental workers’ attitudes towards DDs and screened for question items suitable for the domestic dental education model and may be related to the purpose of our research from these studies. Then, we conducted a face-to-face interview with five dental interns to understand their use of DDs, the DD training they received and their understanding of DDs. Finally, combined with the researcher’s many years of experience teaching dental students, an initial questionnaire containing 49 items was compiled. Four experts in relevant fields (including two dental educators and two endodontic specialists, all with senior professional titles) were invited to evaluate the structure of the questionnaire and the correlation between each item and the content to be investigated. According to the expert discussion and opinion, some inappropriate items were deleted, items with repeated sentences and connotations were merged, and the expressions of some items were modified and adjusted. Based on the content validity evaluation of the expert group, a questionnaire with 43 items was designed, inquiring about various aspects of DD use. A pilot study was conducted on a random sample of students (n=20) to ensure that the questions were not difficult to understand and that no changes needed. A copy of the full questionnaire can be found in online supplemental file 1. The main contents were as follows:

Personal information of the respondents, such as sex, age and name of dental school.

The DD training received by students and their views on it, as well as the self-assessment of the training effect. In this study, students’ proficiency with DD application is divided into four levels.25 Level 0 means they basically do not have knowledge of DDs; level 1 means they have some knowledge but have no practical experience; level 2 means they have some knowledge and have handled simple cases but cannot handle complex cases and level 3 means they have fully mastered DD application and can handle any situation.

Information relating to intracoronal restorations and root canal treatment during the internship and the application of DDs in these procedures.

Students' attitudes towards some aspects of DDs.

Intended future use of DDs during independent practice.

Trained and qualified dental professionals acted as investigators. One month before graduation, all students of the two schools were sent an informed consent document and a link to an online questionnaire. If they agreed to participate in the survey, they could access the questionnaire page through the link provided. If the students encountered any problems when completing the questionnaire, they could contact the investigator at any time for help. To measure the test–retest reliability of the questionnaire, 20 students who returned the questionnaire the first time were selected to complete the questionnaire again 2 weeks after the first survey. The consistency of the two questionnaires was determined by the kappa value, which was greater than 0.9.

If there were missing or incorrectly completed items in a questionnaire, the questionnaire was excluded. After manual verification, the collected data were double-entered. SPSS software (V.20, SPSS) was used for statistical analysis. Frequencies/percentages and means/SDs are shown to describe categorical and continuous variables, respectively, and the χ2 test or Fisher’s exact test was used to compare categorical variables. A p<0.05 was considered statistically significant.

Patient and public involvement

Some selected students were involved in the development and validation of the questionnaire. In face-to-face interviews or pilot studies, they had the opportunity to provide feedback on the content and wording of the questionnaire. The information they provided was used to develop and revise the questionnaire. Students were not involved in the design, recruitment or conduct of the study.

Results

A total of 245 questionnaires were distributed, and 238 questionnaires were returned. All of the returned questionnaires were valid. Finally, 76 CQMU students (23 males and 53 females with an average age of 23.2±0.61 years) and 162 CQTGMC students (47 males and 115 females with an average age of 21.53±0.80 years) were included in this study.

The students’ views on the DD training received and the self-assessment of the training effect are reported in table 1. Generally, all respondents listened to theoretical courses in the school classroom, but few watched a teacher’s demonstration or practised DD themselves, which was more significant among junior college students (p<0.05). A total of 47.5% of the respondents used DDs on real patients during their internships (CQMU=59.2%, CQTGMC=42.0%, p<0.05). The respondents were most satisfied with the theoretical teaching they received (89.9%), followed by watching multimedia resources (67.6%), watching teacher demonstrations (42.4%), simulation exercises (24.8%), and clinical practice (24.4%). In the self-assessment of the mastery of DD technology, 25.2% of the respondents rated it as ‘level 0’, 47.1% as ‘level 1’, 20.6% as ‘level 2’ and only 7.1% as ‘level 3’. Only 19.7% of the respondents claimed that they had received adequate education during their dental school studies. A total of 97.1% of the respondents were willing to receive further training on DD use in the following areas: theoretical teaching (33.8%), watching multimedia resources (61.5%), watching teacher demonstrations (62.3%), simulation exercises (71.4%) and clinical practice (68.8%).

Table 1

The students’ views on the DD training received and the self-assessment of the training effect

	Total	CQMU	CQTGMC	P value
Please select the form of DD training you have received
Listening to theoretical lectures in the school classroom	238 (100.0)	76 (100.0)	162 (100.0)	–
Listening to small lectures or other forms of theoretical training in internship institutions	66 (27.7)	21 (27.6)	45 (27.8)	0.981C
Watching video, animation and other multimedia teaching resources	173 (72.7)	63 (82.9)	110 (67.9)	0.016*C
Watching a teacher’s demonstration on the tooth model	107 (45.0)	42 (55.3)	65 (40.1)	0.029*C
Watching a teacher’s demonstration on simulated patients	25 (10.5)	14 (18.4)	11 (6.8)	0.006*C
Watching a teacher’s demonstration on a real patient during the internship	117 (49.2)	45 (59.2)	72 (44.4)	0.034*C
Practicing on a tooth model	70 (29.4)	37 (48.7)	33 (20.4)	0.000*C
Practicing on simulated patients	21 (8.8)	5 (6.6)	16 (9.9)	0.403C
Practicing real patients during the internship	113 (47.5)	45 (59.2)	68 (42.0)	0.013*C
Please choose the DD training you are satisfied with
Theoretical teaching	214 (89.9)	72 (94.7)	142 (87.7)	0.091C
Watching multimedia resources	161 (67.6)	60 (78.9)	101 (62.3)	0.011*C
Watching teacher demonstrations	101 (42.4)	46 (60.5)	55 (34.0)	0.000*C
Simulation exercises	59 (24.8)	25 (32.9)	34 (21.0)	0.047*C
Clinical practice	58 (24.4)	26 (34.2)	32 (19.8)	0.015*C
Please assess your current mastery of DD technology
Level 0	60 (25.2)	11 (14.5)	49 (30.2)	0.036*C
Level 1	112 (47.1)	41 (53.9)	71 (43.8)
Level 2	49 (20.6)	20 (26.3)	29 (17.9)
Level 3	17 (7.1)	4 (5.3)	13 (8.0)
Do you think you have received adequate DD training in dental school
Yes	47 (19.7)	22 (28.9)	25 (15.4)	0.015*C
No	191 (80.3)	54 (71.1)	137 (84.6)
Please select the areas where you would like to receive further training on DD
Theoretical teaching	78 (33.8)	26 (34.2)	52 (33.5)	0.920C
Watching multimedia resources	142 (61.5)	43 (56.6)	99 (63.9)	0.285C
Watching teacher demonstrations	144 (62.3)	51 (67.1)	93 (60.0)	0.295C
Simulation exercises	165 (71.4)	50 (65.8)	115 (74.2)	0.184C
Clinical practice	159 (68.8)	49 (64.5)	110 (71.0)	0.317C
I do not need further training	7 (2.9)	0 (0.0)	7 (4.3)	0.100F

*P<0.05.

C, p value from χ2 test; CQMU, Chongqing Medical University; CQTGMC, Chongqing Three Gorges Medical College; DD, dental dam; F, p value from Fisher’s exact Test.

The classification of the internship institutions and clinical instructors of students are shown in tables 2 and 3, respectively. A total of 57.1% (136/238) of the respondents reported that they had received clinical training in DD during their internships. Furthermore, the proportions of respondents who received DD training in public stomatological hospitals, stomatology departments of public general hospitals and private clinics were 72.6% (61/84), 50.0% (62/124) and 43.3% (13/30), respectively. In addition, 106 respondents were instructed by endodontic specialists, of which 64.2% (68/106) received DD training from endodontic specialists. In total, 44.9% (66/147) and 7.6% (9/118) of the respondents were instructed by general dental practitioners and non-endodontic specialists, respectively.

The mandatory usage and actual application of DDs reported by the respondents in adult/paediatric patients and in clinical procedures is shown in table 4. All the respondents treated adult patients, and 47.4% used DDs in adult patients. A total of 210 respondents treated paediatric patients, of whom 26.2% used DDs in paediatric patients. DDs are not mandatory for either adult or paediatric patients. There were 227, 213, 233, 216 and 140 respondents who had performed composite restoration on anterior teeth, glass-ionomer restoration on anterior teeth, composite restoration on posterior teeth, glass-ionomer cement restoration on posterior teeth and amalgam restoration on posterior teeth, respectively. The DD use rates in these procedures were 25.6% (58/227), 21.1% (45/213), 39.1% (91/233), 28.7% (62/216) and 21.4% (30/140), respectively. DDs are not mandatory for the above restorative procedures. There were 228, 224 and 215 respondents who had performed root canal treatment on anterior teeth, premolars and molars, respectively. In these procedures, the DD use rates were 27.2% (62/228), 33.0% (74/224) and 41.9% (90/215), and the compulsory utilisation rates of DD were only 0% (0/228), 0.9% (2/224) and 1.4% (3/215).

Table 4

DD use in adult/paediatric patients and in various clinical procedures

	Mandatory usage of DD, N (%)		Actual application frequency of DD, N (%)						I have never done this before
	Mandatory	Optional	Always (100%)	Mostly(76%–99%)	Often (51%–75%)	Occasionally (26%–50%)	Rarely (1%–25%)	Never (0%)
Adult patients
CQMU	0 (0.0)	76 (100.0)	0 (0.0)	6 (7.9)	12 (15.8)	9 (11.8)	18 (23.7)	31 (40.8)	0
CQTGMC	0 (0.0)	162 (100.0)	0 (0.0)	5 (3.1)	8 (4.9)	19 (11.7)	36 (22.2)	94 (58.0)	0
Child patients
CQMU	0 (0.0)	53 (100.0)	0 (0.0)	2 (3.8)	4 (7.5)	3 (5.7)	6 (11.3)	38 (71.7)	23
CQTGMC	0 (0.0)	157 (100.0)	0 (0.0)	3 (1.9)	5 (3.2)	10 (6.4)	22 (14.0)	117 (74.5)	5
Anterior composites
CQMU	0 (0.0)	71 (100.0)	0 (0.0)	3 (4.2)	3 (4.2)	5 (7.0)	8 (11.3)	52 (73.2)	5
CQTGMC	0 (0.0)	156 (100.0)	0 (0.0)	3 (1.9)	9 (5.8)	9 (5.8)	18 (11.5)	117 (75.0)	6
Anterior glass-ionomer cement
CQMU	0 (0.0)	60 (100.0)	0 (0.0)	2 (3.3)	4 (6.7)	3 (5.0)	5 (8.3)	46 (76.7)	16
CQTGMC	0 (0.0)	153 (100.0)	0 (0.0)	2 (1.3)	6 (3.9)	7 (4.6)	16 (10.5)	122 (79.7)	9
Posterior composites
CQMU	0 (0.0)	74 (100.0)	0 (0.0)	3 (4.1)	5 (6.8)	9 (12.2)	18 (24.3)	39 (52.7)	2
CQTGMC	0 (0.0)	159 (100.0)	0 (0.0)	6 (3.8)	12 (7.5)	12 (7.5)	26 (16.4)	103 (64.8)	3
Posterior glass-ionomer cement
CQMU	0 (0.0)	64 (100.0)	0 (0.0)	1 (1.6)	5 (7.8)	6 (9.4)	14 (21.9)	38 (59.4)	12
CQTGMC	0 (0.0)	152 (100.0)	0 (0.0)	4 (2.6)	6 (3.9)	9 (5.9)	17 (11.2)	116 (76.3)	10
Posterior amalgams
CQMU	0 (0.0)	33 (100.0)	0 (0.0)	0 (0.0)	0 (0.0)	3 (9.1)	5 (15.2)	25 (75.8)	43
CQTGMC	0 (0.0)	107 (100.0)	0 (0.0)	1 (0.9)	1 (0.9)	6 (5.6)	14 (13.1)	85 (79.4)	55
Root canal treatment of anterior teeth
CQMU	0 (0.0)	66 (100.0)	1 (1.5)	4 (6.1)	5 (7.6)	1 (1.5)	2 (3.0)	53 (80.3)	10
CQTGMC	0 (0.0)	162 (100.0)	0 (0.0)	3 (1.9)	8 (4.9)	14 (8.6)	24 (14.8)	113 (69.8)	0
Root canal treatment of premolar teeth
CQMU	2 (3.2)	61 (96.8)	2 (3.2)	3 (4.8)	7 (11.1)	4 (6.3)	8 (12.7)	39 (61.9)	13
CQTGMC	0 (0.0)	161 (100.0)	0 (0.0)	5 (3.1)	6 (3.7)	14 (8.7)	25 (15.5)	111 (68.9)	1
Root canal treatment of molar teeth
CQMU	3 (4.9)	58 (95.1)	3 (4.9)	6 (9.8)	10 (16.4)	4 (6.6)	7 (11.5)	31 (50.8)	15
CQTGMC	0 (0.0)	154 (100.0)	0 (0.0)	7 (4.5)	13 (8.4)	14 (9.1)	26 (16.9)	94 (61.0)	8

CQMU, Chongqing Medical University; CQTGMC, Chongqing Three Gorges Medical College; DD, dental dam.

A total of 145 and 141 respondents had never used DDs in restorative procedures or endodontic treatment during their internships, respectively. The reasons for not using DDs are shown in table 5. Among these two groups, the most common reason was ‘I lack knowledge and experience’ (‘never used in restorative procedures’ group=69.0%, ‘never used in endodontic treatment’ group=73.0%), and more respondents from CQTGMC believed that ‘DDs are not provided by internship institutions’ than students from CQMU (p<0.05). In the ‘never used in restorative procedures’ group, more respondents from CQTGMC thought that DD was not necessary than those from CQMU (p<0.05), but there was no such difference in the ‘never used in endodontic treatment’ group (p>0.05).

Table 5

The reasons students did not use DDs

	Never used in restorative procedures, N (%)				Never used in endodontic treatment, N (%)
	Total (N=145)	CQMU (N=39)	CQTGMC (N=106)	P value	Total (N=141)	CQMU (N=46)	CQTGMC (N=95)	P value
DDs are considered to have disadvantages (such as time-consuming, inconvenient, etc)	33 (22.8)	8 (20.5)	25 (23.6)	0.696C	38 (27.0)	14 (30.4)	24 (25.3)	0.516C
I lack knowledge and experience	100 (69.0)	23 (59.0)	77 (72.6)	0.115C	103 (73.0)	33 (71.7)	70 (73.7)	0.807C
I do not think they are necessary	38 (26.2)	4 (10.3)	34 (32.1)	0.008*C	18 (12.8)	4 (8.7)	14 (14.7)	0.314C
DDs are not provided by internship institutions	42 (29.0)	3 (7.7)	39 (36.8)	0.001*C	42 (29.8)	3 (6.5)	39 (41.1)	0.000*C
Patients were unwilling or refused to use DDs	27 (18.6)	7 (17.9)	20 (18.9)	0.900C	26 (18.4)	10 (21.7)	16 (16.8)	0.482C
Other reasons	4 (2.8)	1 (2.6)	3 (2.8)	1.000F	4 (2.8)	1 (2.2)	3 (3.2)	1.000F

*P<0.05.

C, p value from χ2 test; CQMU, Chongqing Medical University; CQTGMC, Chongqing Three Gorges Medical College; DD, dental dam; F, p value from Fisher’s exact test.

The respondents were asked to agree or disagree with some aspects of DDs. The statements and their responses are reported in table 6. Most of the respondents claimed that DDs allowed clearer access to the operating site (97.1%), reduced the incidence of swallowing or inhaling (99.6%), and enabled a higher clinical standard to be achieved (91.2%). At the same time, the respondents agreed that adequate isolation cannot be achieved if a DD is not used (79.0%) and that restorations placed while using a DD have greater longevity than those placed without the use of a DD (86.1%). On the other hand, more than half of the respondents expressed the opinion that DDs are difficult to apply (total=52.9%, CQMU=42.1%, CQTGMC=58.0%, p<0.05). Additionally, 60.5% of the respondents stated that patients do not like DDs, with CQTGMC having more respondents who expressed this opinion than CQMU (66.0% vs 48.7%, p<0.05).

Table 6

Agreement or disagreement of students regarding various aspects of DDS

Do you agree with the following statement?	Agree, N (%)		Disagree, N (%)		P value
	CQMU	Cqtgmc	CQMU	Cqtgmc
Adequate isolation cannot be achieved if a DD is not used	61 (80.3)	127 (78.4)	15 (19.7)	35 (21.6)	0.742C
DDs enable clearer access to the operating site	73 (96.1)	158 (97.5)	3 (3.9)	4 (2.5)	0.683F
The difficulty of the restoration phase will be reduced once a DD is used	73 (96.1)	146 (90.1)	3 (3.9)	16 (9.9)	0.116C
The use of a DD can reduce the incidence of swallowing or inhaling	76 (100.0)	161 (99.4)	0 (0.0)	1 (0.6)	1.000F
DD placement should be compulsory before endodontic treatment	34 (44.7)	89 (54.9)	42 (55.3)	73 (45.1)	0.142C
DDs are difficult to apply	32 (42.1)	94 (58.0)	44 (57.9)	68 (42.0)	0.022*C
DDs enable a higher clinical standard to be achieved	68 (89.5)	149 (92.0)	8 (10.5)	13 (8.0)	0.526C
Restorations placed while using a DD have greater longevity than those placed without the use of a DD	65 (85.5)	140 (86.4)	11 (14.5)	22 (13.6)	0.852C
DDs increase the difficulty of intraoperative radiography	55 (72.4)	103 (63.6)	21 (27.6)	59 (36.4)	0.181C
Assistance is necessary during DD application	68 (89.5)	154 (95.1)	8 (10.5)	8 (4.9)	0.108C
Patients do not like to use DDs	37 (48.7)	107 (66.0)	39 (51.3)	55 (34.0)	0.011*C
DD application is time-consuming and reduces work efficiency	36 (47.4)	87 (53.7)	40 (52.6)	75 (46.3)	0.362C
Before using a DD, the patient should be asked about their history of latex allergies	76 (100.0)	155 (95.7)	0 (0.0)	7 (4.3)	0.100F

*P value < 0.05.

C, p value from χ2 test; CQMU, Chongqing Medical University; CQTGMC, Chongqing Three Gorges Medical College; F, p value from Fisher’s exact test.

The opinions of students about the intended future usage of DDs are shown in table 7, with 92.1% of the CQMU respondents and 95.1% of the CQTGMC respondents indicating that they would like to use DDs in their private practices. Among them, 44.2% (99/224) were willing to use DDs in adults, 1.3% (3/224) were willing to use DDs in children and 54.5% (122/224) were willing to use DDs in both adults and children. A total of 12.5% (28/224) of the respondents said they would use DDs only for endodontic treatment, 12.1% (27/224) indicated that they would use DDs for restorative procedures, and 75.4% (169/224) reported that they would use DDs for all procedures indicated.

Table 7

Opinion of students about the intended future usage of DDS

When working independently in the future, I intend to use DDs	Total (N=224)	Cqmu (N=70)	Cqtgmc (N=154)	P value
In adult or child patients
In both adults and children	122 (54.5)	33 (47.1)	89 (57.8)	0.015*F
Only in adults	99 (44.2)	34 (48.6)	65 (42.2)
Only in children	3 (1.3)	3 (4.3)	0 (0.0)
During restorative procedures or endodontic treatment
During all procedures indicated	169 (75.4)	48 (68.6)	121 (78.6)	0.245C
Only during restorative procedures	27 (12.1)	10 (14.3)	17 (11.0)
Only during endodontic treatment	28 (12.5)	12 (17.1)	16 (10.4)

*P< 0.05.

C, p value from χ2 test; CQMU, Chongqing Medical University; CQTGMC, Chongqing Three Gorges Medical College; F, p value from Fisher’s exact test.

Discussion

DDs can effectively protect both doctors and patients, fully reflect the preferred treatment strategies and professional level of dentists, and improve patients’ treatment experiences.3 In dental school education, especially with respect to clinical practice tactics, it is very important to train students so that they have theoretical knowledge and operative skills regarding DD application. This training would not only affect the clinical utilisation rate and operation level of DDs but also influence young dentists' planning and choices in their future work. This study investigated the current use of DDs, attitudes towards DDs, and intended future use of DDs among final-year dental students. As the DD trainings received by students from CQMU and CQTGMC were quite different, the relevant results are reported by school to reflect the situation more accurately.

A survey on the topic found that it is easier for respondents to report what they think is the right answer rather than the real answer.9 17 However, in this study, the respondents were all school students, and they were more likely to express their true thoughts than doctors who were under the pressure of a challenging environment. In addition, an anonymous survey was adopted, and the answers given by the respondents were effectively kept anonymous, which also ensured the authenticity of the survey results to a certain extent. On the other hand, this study does have some limitations, mainly because it relies on the information provided by a questionnaire rather than direct observation of students’ learning and clinical operations. Some students may not be able to accurately recall their DD training experiences, especially those with in-school training, which may lead to recall bias. In addition, some interns may practice and live in the same place. They are more likely to interact and share attitudes and views. This tendency of consensus may have introduced deviations into the survey results.

In our study, 59.2% of the CQMU respondents and 42.0% of the CQTGMC respondents had applied DDs to adult patients, which was lower than the rate reported in similar international surveys.2 16 17 Mala et al2 surveyed 87 British and Irish students and found that 99% of respondents used DDs in adult patients. Other data from Saudi Arabia showed that all 294 of their respondents had used DDs in adult patients.17 According to Tanalp et al,16 there are two dental schools in Turkey where DDs are mandatory for endodontic treatment. Therefore, considering the advantages of DDs, extensive and routine DD applications should be emphasised in the two schools we investigated. In fact, the relevant policies in the field of dental education have improved at the national level. According to the revised examination syllabus for stomatological practitioners in 2018, DD technology was listed as a practical skill examination item.26 This improvement is conducive to promoting education and training related to DDs. More detailed teaching plans should be developed by Chinese dental schools to cultivate qualified students who meet the national standards.

The main reasons the students did not use DDs were ‘I lack knowledge and experience’ and ‘DDs are not provided by internship institutions’. In China, the DD utilisation rate in general clinical practice is lower than that in other developed countries,25 and dental schools usually do not require students to use DDs in practice.3 In this study, a few students reported that their clinical instructors had taught them to use DDs and were required to mandate DD use during the internship. According to Zou et al,25 the nonuse of DDs by dentists is a result of being taught by trainers who could not or did not use them. It is important that dental educators consistently use DDs and train their students to use them. Therefore, it is the responsibility of dental schools and clinical instructors to provide students with opportunities and materials other than classroom teaching to master the use of DD.18

The advantages of DDs, such as full isolation of the operation area, reduced inhalation and swallowing of instruments, and facilitation of a higher clinical standard, are generally recognised by students. On the other hand, approximately half of the students thought that DD use was difficult and time-consuming. More than 20% of the students did not use DDs because they did not want to spend time on an application that is difficult for them. Previous studies13 14 have shown that these factors also limit dentists’ use of DDs. Although there are many other isolation methods (cotton roll, saliva evacuators, etc), none can exceed the safety and effectiveness provided by DDs.9 10 The effectiveness of technology improves with experience.9 Therefore, in dental education, it may be necessary to emphasise DD operational skills to improve students' operational proficiency and reduce their negative views of DDs.2

In the two schools investigated, although most students received theoretical teaching on DDs, the proportion of students who watched teachers' demonstrations and practiced using DDs has decreased significantly. Students were less satisfied with the simulation exercises and clinical practice on the use of DDs, and most of the respondents were willing to receive further DD training. These findings highlight the problem in merely talking about stratagems on paper when teaching DD use in the school curriculum, which may lead students to know that only DDs should be applied but not know how to apply them. Therefore, as proposed by SAH et al,21 preclinical simulation exercises and clinical hands-on practice should be increased, since the ability to successfully place DDs in a variety of clinical situations requires practice and clinical experience that cannot otherwise be taught.

In this study, 92.1% of the CQMU respondents and 95.1% of the CQTGMC respondents indicated that they would like to use DDs when working independently in the future. However, surveys of dentists in independent practice have shown that the utilisation rate of DDs is not high.15 20 25 27 Students who are educated through contemporary educational methods are exposed to the latest treatment concepts and are more likely to practice the isolation methods taught by dental schools after graduation.25 Pertinently, previous studies have shown that DD use is greater in newly qualified graduates than in older practitioners.28 29 However, Jenkins et al30 came to the opposite conclusion, showing that older practitioners are more likely to use DDs than their younger counterparts. Dentists with additional training may be more likely to use DDs.25 These findings suggest that the role of education in the promotion of the clinical application of DDs should not be ignored.

Within the sample examined, DDs were mainly used in endodontic treatment. In addition, nearly 90% of the students indicated that they would like to use DDs in endodontic treatment in the future. Although DDs are usually the first choice in root canal procedures, their role in other procedures should not be ignored. The present research mainly focuses on the application of DDs in endodontics.31 At the same time, dental education emphasises that DDs are an important part of endodontics, and their effectiveness in other procedures is rarely mentioned.16 These factors may lead students to believe that DDs and endodontic treatment are interrelated. In this study, 44.7% of the CQMU students and 54.9% of the CQTGMC students reported that DD placement before endodontic treatment is compulsory.

The samples included in this study seem to be highly representative because they came from two dental schools in Chongqing, and the rate of lost to follow-up was very low. Local dental instructors and educational decision-makers could benefit from our study. However, the present findings are limited to the city of Chongqing. Future studies with a broad inclusion of interns and dental schools are recommended, as they would be more representative of the population of Chinese dental students.

Conclusion

Overall, although final-year students are aware of the advantages of DDs, they are still not comfortable with the use of DDs, creating uncertainty about the future integration of this tool in routine practice. In addition, there may be a lack of hands-on training for students in the teaching of DD use in school curricula, and there is room to enhance the education on DD use. In view of the important role of education in promoting the clinical application of DD, dental schools have a responsibility to continuously improve their teaching measures and emphasise the advantages of using DDs during an internship to cultivate competent future dentists.

Table 2

The classification of internship institutions

	Please select the type of internship institution you worked in during your last year of internship, N (%)				Please select the type of internship institution where you receive DD clinical training, N (%)
	Total (N=238)	CQMU (N=76)	CQTGMC (N=162)	P value	Total (N=136)	CQMU (N=56)	CQTGMC (N=80)	P value
Public stomatological hospital	84 (35.3)	75 (98.7)	9 (5.6)	0.000*C	61 (44.9)	56 (100.0)	5 (6.3)	0.000*C
Stomatological department of public general hospital	124 (52.1)	1 (1.3)	123 (75.9)		62 (45.6)	0 (0.0)	62 (77.5)
Private clinic	30 (12.6)	0 (0.0)	30 (18.5)		13 (9.6)	0 (0.0)	13 (16.3)

*P<0.05.

C, p value from χ2 test; CQMU, Chongqing Medical University; CQTGMC, Chongqing Three Gorges Medical College; DD, dental dam.

Table 3

The classification of clinical instructors

	Please select the types of clinical instructor(s) who has instructed you,N (%)				Please select the type of clinical instructor(s) who instructed you to use DDs during your internship, N (%)
	Total (N=238)	CQMU (N=76)	CQTGMC (N=162)	P value	Total (N=136)	CQMU (N=56)	CQTGMC (N=80)	P value
Endodontic specialist	106 (44.5)	76 (100.0)	30 (18.5)	0.000*C	68 (50.0)	53 (94.6)	15 (18.8)	0.000*C
General dental practitioner	147 (61.8)	2 (2.6)	145 (89.5)	0.000*C	66 (48.5)	1 (1.8)	65 (81.3)	0.000*C
Nonendodontic specialist	118 (49.6)	76 (100.0)	42 (25.9)	0.000*C	9 (6.6)	3 (5.4)	6 (7.5)	0.736F

*P<0.05.

C, p value from χ2 test; CQMU, Chongqing Medical University; CQTGMC, Chongqing Three Gorges Medical College; DD, dental dam; F, p value from Fisher’s exact test.