Eligibility Criteria: The present systematic review included the studies conducted on oral health and knowledge of dental professionals towards swine flu. Study selection was based on following inclusion criteria: 1) studies on dental professionals; 2) studies conducted on Indian population; 3) studies in which the outcome measures are knowledge and awareness; 4) studies that were cross-sectional and observational in nature. There were no limitations regarding publication dates and language used in the studies, in the search strategy. Studies that were excluded from the present review were: 1) studies conducted elsewhere but not in India; 2) review articles on swine flu; 3) studies focussing only on medical professionals; 4) unpublished material and abstracts.

Identification of appropriate studies: Search strategy utilized in the present systematic review is depicted in [Table/Fig-1].

[Table/Fig-1]:

Flow diagram of various studies included in the review.

The present review was conducted according to the mentioned protocol and guidelines [9]. Relevant literature search was carried out through search of scientific databases like MEDLINE, EMBASE, Pubmed Databases using MESH terms- ‘preventive measures’, ‘dentists’ and ‘transmission’etc., irrespective of the date of publication. Manual search was also conducted from Institutional and PGIMER library. Online search engines like ‘Google Scholar’ were also assessed using various keywords - knowledge, awareness, swine flu, H1N1, dental professionals, India, etc. Various combinations of key words were made using ‘and’, ‘or’ as Boolean operators. We identified 28 papers with these methods. Where possible, all terms were included as full text, with truncation used where possible to capture variation in the terminology. Finally three articles were selected for inclusion in the review.

Selection of studies: All the examiners were trained in the department by experts to select and retrieve the data for conducting the review and calibrated (kappa=0.8). Duplicate studies were removed by two authors (RSH & PP) from the list of studies that was obtained after conducting manual and electronic search. Thereafter, abstracts and titles of the studies were screened to select those studies that fulfilled the inclusion criteria. Inter-examiner reliability was good. Review articles on swine flu were not included but their references were screened in order to make sure that no study should be left behind. Screening of the selected studies was done using STROBE checklist [10].

Control of bias assessment: A thorough literature search was conducted to find a suitable tool that assessed the quality of observational studies. Issues that were addressed regarding the risk of bias and quality assessment were as follows: (1) completeness of reporting information regarding swine flu, (2) incomplete outcome reporting, (3) reporting a single outcome measure (assessing only knowledge or awareness), (4) design of the study, and (5) any conflict of interest present in the study. After addressing all the criteria in the above mentioned issues, the overall plausible risk of bias in the studies was estimated as moderate to low.

Quality assessment and extraction of data: Mandatory guidelines (PRISMA) were followed in order to do the quality assessment of the studies [11]. The qualifying criteria was satisfactorily met by all the studies. A pre-determined data collection form was used by two other authors (TN & GA) independently to extract the following information: 1) study title; 2) year of publication of the study; 3) geographical area in which the study originated; 4) number of study subjects; 5) design of the study; and 6) knowledge and awareness level regarding swine flu. The fifth author (AK) sorted out any kind of disagreement regarding article screening and extraction. For obtaining missing or unclear data, corresponding authors of selected studies were contacted through emails. One author was contacted by us for the above purpose.

Description of selected studies: The original search identified 28 studies and only three studies were potentially eligible for the present systematic review after performing necessary exclusions [12–14]. The study population in two studies included dental students also, whereas in one study it comprised entirely of practicing dentists. A summary of various study characteristics is mentioned in [Table/Fig-2]. All the three studies were conducted in different geographical regions of the country (Andhra Pradesh, Haryana and Rajasthan). All included studies were cross-sectional studies and utilized a self-structured, close ended questionnaire for congregation of the data on knowledge and awareness concerning swine flu.

Gender and educational qualification of subjects: Gender and educational qualification of subjects was mentioned in two of the three studies [13,14]. It can be noted that three-fourths of the subjects were males and 45.6% of subjects were postgraduates (MDS) in the study reports of Kaipa et al., [14] [Table/Fig-3]. Female subjects and students who belonged to clinical categories had significantly higher knowledge scores as compared to their male counter parts in the study reports of Singh et al., (p=0.001) [13]. On the contrary, Kaipa et al., [14] in their study reported that males had significantly higher knowledge as compared to females.

Knowledge and awareness regarding the H1N1 virus and its transmission: Majority of the subjects (92.6%) had heard about swine flu, and 64.3% of them knew about the H1N1 virus in the study reports of Singh et al., [13]. Study findings of Palwankar et al., revealed that more than 50% of subjects were aware about H1N1 virus [12]. Study reports of Kaipa et al., showed that all the subjects (100%) were aware that swine flu is an air-borne disease but only 51.8% of the subjects were conscious of the fact that the disease can spread even during the prodromal period and not just after one develops the symptoms [14]. Awareness regarding transmission was reported by only 51% in the study findings of Palwankar et al., [12].

Awareness regarding vaccination and steps taken by health care authorities: More than 80% of subjects were aware regarding the availability of swine flu vaccine in the study reports of Kaipa et al., [14] as compared to study findings of Palwankar et al., [12] in which only 31.5% had awareness [Table/Fig-4]. Moreover, Singh et al., [13] observed in their study that nearly 80% of the subjects were of the opinion that health care authorities were taking necessary steps to control the risk of pandemic and 43.6% of subjects were aware of hospital near to their clinic that has been designated by the government for the treatment of swine flu in the study reports of Kaipa et al., [14].

Awareness regarding various preventive measures for swine flu: More than 50% of subjects in two studies [12,13] and 100% of subjects in the other study [14] were of the opinion that frequent hand washing and use of sanitizer are one of the effective methods to prevent swine flu [Table/Fig-5]. Wearing a surgical mask, undergoing vaccination for swine flu and quarantine were other less preventive methods cited by study subjects.

[Table/Fig-5]:

Perceived efficacy of various preventive methods for swine flu among subjects in different studies.

The emphasis of the present systematic review was on the knowledge and awareness regarding swine flu (H1NI) among dental professionals in India. The review focused on various parameters mentioned in different studies in order to accumulate information regarding swine flu among dental professionals which is evident from the results.

Strengths and weaknesses of the review: This systematic review involved the search of multiple electronic databases, with no restrictions regarding language or year of publication. The reference lists of literature reviews were searched for other studies that could also be included. However, it was not possible to search technical reports, papers from research groups or committees and preprints and it is possible that some relevant data may have been left behind. This could have accounted for some publication bias. Efforts were also made to find studies in which dental professionals could have been hidden as a confounder but not as main subject.

Moreover, there was under-reporting of some relevant information (descriptive data, questionnaire) related to knowledge, attitude and awareness among dental professionals in one study [12]. As a result of this, some important aspects pertaining to knowledge and awareness were not included and compared with other studies that were included in the review. Because of the marked variability in the questionnaire and outcomes of the included studies, it was not possible to combine the data and perform meta-analysis.

All investigations were cross-sectional studies. This type of design offers a lower degree of scientific evidence compared with case-control and cohort studies. Moreover, there are inherent limitations in terms of methodological issues, generalizability and internal validity when we are dealing with cross-sectional studies. However, the use of scales for quality assessment has limitations that should be considered.

All the studies used a close-ended questionnaire to obtain information about various aspects relating to swine flu. Such type of questionnaire reduces recall bias and such questions are easy to analyse and may achieve quicker response from the subjects. It cannot be verified that whether the responses given by the subjects in conjectural situations posed in different studies would accurately justify the subject’ response in real circumstances. The final important issue is the lack of external validity. All the three studies offered no information regarding the sample size calculation and/or the analyzed population constituted a convenience sample.

Statement of principal findings: A significantly higher knowledge regarding swine flu was reported among males as compared to females in the study reports of Kaipa et al., [14]. This difference could be attributed due to more interactive and socialization aspect of males as compared to females. This holds particularly well for a country such as India where traditional norms and customs discriminate against females [15]. Influence of education was also seen on knowledge as subjects belonging to clinical categories had more knowledge scores as compared to their pre-clinical counterparts [13].

It was reported in two studies [12,14] that only 51% of subjects had correct knowledge regarding transmission of swine flu. This information is crucial as not knowing about this may lead dentists to inappropriately triage patients [16]. Diagnostic and treatment facilities were provided by Government of India at selected hospitals in the endemic states following pandemic alert by WHO in order to curb the misuse of the facilities by false positive cases [17]. A substantial proportion of subjects were aware of such a facility in the study reports of Kaipa et al., [14].

The best way to prevent the spread of swine flu virus is by washing hands frequently and avoiding patients having flu like symptoms [18]. Majority of subjects in all the three studies believed that frequent hand washing and use of sanitizer as an effective and preventive measure. However, wearing basic face masks cannot protect people from being infected.

Pandemic outbreak caused by H1N1 virus and other infectious disease agents still remains the biggest threat to human beings due to high mortality rate associated with their infections. The present review concluded that majority of the subjects had substantial knowledge regarding swine flu, yet there were notable deficiencies regarding the transmission, preventive measures and availability of vaccine. The present review emphasizes the need for appropriate training regarding infectious diseases during the undergraduate dental curriculum and continuous education programs after graduation.

Dental professionals and dental students must play an active role in ongoing research regarding swine flu and its prevention. This may increase the awareness of the disease amongst dentists, and may also highlight the important role that they can play in decreasing the mortality during future disease outbreaks. As only three studies have been assessed the validity reduces and we cannot generalize the results. As the present review only found three studies that were conducted among dental professionals’ knowledge regarding swine flu, there is urgent need for similar studies to be conducted in every part of the country.