This was the first study involving a mixed-method process evaluation of a trial on dentist-delivered behavioural support for ST cessation in an LMIC. While many studies have explored the factors that influence the implementation of tobacco cessation interventions in dental settings, there is limited evidence on the process evaluation of such studies in dental settings in low resource settings.

Overall, the dentists in the current study found it practical to deliver a behavioural support intervention in routine practice, however, certain issues were identified. Workload, time management and lack of privacy were some of the key issues and these factors have been frequently identified as barriers towards the implementation of tobacco cessation support within dental and other clinical settings, in previous literature [24]. For instance, a mixed-method implementation study assessing the feasibility of tobacco cessation, in a clinical (primary care) setting in Nepal, reported the issue of patients having to wait for long (up to an hour or were asked to visit the next day) to be counselled, due to workload/time availability [24].

Likewise, the infrastructure of the dental settings has also been reported in the literature as a barrier towards identifying users and offering tobacco cessation support. For instance, concern over the lack of privacy, due to the ward setting within the dental hospitals was reported in a more recent qualitative study exploring barriers towards ST cessation support in dental hospitals in a LMIC [25]. Likewise, the authors of another study, which assessed the feasibility of tobacco cessation in primary care settings, reported the potential contribution of the infrastructure of the clinical setting towards a low level of identification of tobacco users in the study [24]. The lack of privacy in the ward settings can undermine the practicality of the intervention in routine. While arranging a private space for taking a history of tobacco use, might not be practical in low-resource clinical settings, future trials should consider training the participating dentists on the skills required to take ST use history when no arrangements for privacy can be made.

Regarding the intervention delivery, most dentists in the current study did not deliver the intervention as planned. Literature on the dentists’ compliance with behavioural interventions for tobacco cessation is lacking, however, the findings of the current study are in keeping with the existing literature, regarding compliance with the protocol in non-pharmacological interventions [26–28]. For instance, in a multi-centre trial, Hovell et al. [28], reported that orthodontists did not deliver the tobacco cessation intervention as planned and that the anti-tobacco counselling was less seldom offered to the dental patients by the orthodontics in the intervention group. While the dentists’ non-compliance with the intervention delivery, could have been due to several reasons, the pragmatic approach to intervention delivery in our trial might have contributed towards the deviation from the protocol in intervention delivery. The dentists’ perceptions and beliefs and the patients’ responses and socioeconomic profile, might have influenced the delivery of the intervention. These findings are in line with the existing literature, as it is well established, that in addition to other factors (such as external, and organisational/contextual factors), how the individuals think, also influences the implementation of complex interventions [29, 30]. This brings us to one of the most debated topics in the translation of evidence-based health interventions, i.e., whether fidelity and adaptation can co-exist [30–32]. Behavioural interventions, among other things, are influenced by the socioeconomic needs of the patients, their responses and the beliefs and views of the provider. Therefore, given the adaptive nature of behavioural interventions, striking the right balance between flexibility in adherence (to allow for a pragmatic approach) and standardising the intervention, can be challenging, especially where tailoring is also a key quality element [32]. More research and a careful consideration are needed on the assessment of fidelity to the delivery of BISCA in clinical settings, especially for pragmatic trials (in which the intervention delivery is left at the discretion of the clinicians).

The dentists’ inability to implement certain items such as the ‘management of withdrawal symptoms and triggers’ were reportedly augmented by the perceptions of the dentists related the stress associated with the patients’ socioeconomic status (most naswar users belong to low socioeconomic background), the non-availability of resources to cope with stress in Pakistan, the absence of other cessation support/aids such as nicotine replacement therapies (NRTs) and the lack of cessation clinics in Pakistan. These findings support the existing literature on the barriers towards delivering tobacco cessation support in dental settings [33, 34]. Closely linked to this, are the findings from another pilot study that tested the same intervention (BISCA) in tobacco cessation clinics in Pakistan and England [22]. The cessation advisors in the study, reportedly felt that information on NRTs should be included in the intervention resources [22]. Future trials should therefore, consider including information about commercial nicotine pouches and NRTs in the intervention. The poor implementation of ‘self-reward’ in the current study, is also in keeping with the findings of the earlier BISCA pilot study [22]. Self-reward and self-incentives are techniques that are widely used in behaviour change, but little is known about the effectiveness of these techniques [35]. For instance, a systematic review exploring the effectiveness of these techniques did not find any study on self-reward, whereas the evidence in favour of self-incentives, was reportedly weak [35]. This raises the question of whether these techniques should be employed in behaviour change interventions and to whom and highlights the need for assessing the relevance of self-reward in ST users (and in all tobacco users) from SA.

The positive views expressed by the patients, about the dentist-delivered tobacco cessation support, support the existing literature [36–41]. Likewise, the lack of engagement of one patient with the intervention due to unsatisfactory experience related to the dental, also support the existing literature on the role of context, in that context cannot be divorced from the implementation of complex interventions [30].

The young adults’ reluctance towards tobacco cessation support (self-help material) as reported in the current study, has not been previously reported in literature. One reason could be that much of the literature on young adults’ tobacco cessation is largely from high-income countries [42]. The challenges faced by LMICs in the implementation of tobacco cessation interventions for young adults are perhaps yet to be explored, as they are specific to the sociocultural context of these countries. Future trials should consider the use of text messaging in lieu of take-home resources for younger participants, which they can use without the fear of social disapproval at home.

Regarding the change in the dentists’ clinical behaviour, the findings of the current study support the existing literature on the health professionals’ clinical behaviour with regard to tobacco cessation. For instance, in a pilot trial on tobacco cessation, Monson and Engeswick, observed no change in the dental hygienists’ behaviour of in provision of tobacco cessation support to their patients, after they had received training on the provision of tobacco cessation [43]. Similarly, according to the findings of a study investigating a pilot smoking cessation program in dental offices, none of the dentists had incorporated the tobacco cessation protocol, into their routine practice despite agreeing to do so, citing various reasons similar to what the dentists in the current study had identified [44]. Likewise, no significant impact on the patients’ receipt of tobacco cessation support was observed in another trial investigating a robust method for training clinicians in tobacco cessation [45]. The reasons identified by the dentists in the current study, for not being able to normalise the implementation of tobacco cessation support in routine included: lack of time; cessation support not being part of routine protocol; lack of privacy; fear of offending the patient and; use of tobacco among dentists. These findings are all in keeping with the existing literature [25, 44].

Overall, while much of the wider implementation of the intervention remains to be explored, and the need for a large-scale implementation study cannot be over-emphasized, the findings from the current study have provided some useful insights on the topic. To begin with, there is a need to invest in the capacity building of dentists. This would, among other things, require more emphasis on the treatment of tobacco dependence in the undergraduate curriculum for dentists and refresher training/workshops at the postgraduate level. Imparting the dentists with the skills and building their competence for recording tobacco use history, particularly the history of ST use, also needs attention, as this can positively contribute towards overcoming their reluctance to take ST use history. Other issues likely to be faced in routine implementation would be the lack of time and space. These would require ‘environmental restructuring’ through, for instance, allocating a quiet corner in the department (if not a separate room for the delivery of support). Policy-level support, from the administrative heads of the hospitals, will be required for the implementation of this measure.

Some limitations of the research are acknowledged. The main limitation of the study was that the interviews were conducted by the researchers who were involved in the trial. SR was known to all of the dentists and some of the patients (from previous contact at recruitment and follow-up within the trial). This might have influenced the dentists’ and patients’ responses. For instance, the dentists might not have openly shared their views on the training workshop, as it was facilitated by the research team. Likewise, the patients might not have felt comfortable openly criticising the conduct of the research. To address this issue, all participants (dentists and patients) were reassured before the interview that there are no right and wrong answers and that their responses were needed to improve the intervention and trial processes for future trials. Likewise, the positive change in the patients’ ST use behaviour, might reflect the effectiveness of the intervention or the influence the researcher had on the patients. While abstinence in the trial was verified by salivary cotinine analysis, the self-reported reduction in ST use was not verified. Therefore, the potential social desirability bias with the quit responses cannot be ignored. Another limitation was that the process evaluation did not take into account fidelity to intervention training and therefore relied only on fidelity to intervention delivery to understand non-adherence to the intervention protocol. An independent observation of the intervention training workshop would have strengthened the understanding of why dentists failed to adhere to the intervention protocol. While all participants who received the intervention should have been interviewed, given the time constraints, this was not possible and therefore a small, but diverse sample was selected, to understand the feasibility of the trial and intervention delivery in dental settings. No female patient was interviewed as only one female patient was recruited in the pilot trial and she was lost to follow-up. Furthermore, interviews with patients who were randomised to the control group in the trial were not conducted. Interviews with the control group could have offered a useful comparison between the views of the two groups.