The present study compared clinical marker changes between conventional and E- cigarette smokers with non-smokers, along with the evaluation of salivary inflammatory biomarker changes among patients treated with peri-implantitis. Prior studies outlined the role of cigarette consumption as a risk factor for peri-implantitis and reported conflicting results [37–38]. Recent evidence found that smoking, among various other cofactors, had a negative impact on clinical outcomes and peri-implant lesion resolution . It further stated smoking as an essential risk indicator for surgical peri-implantitis treatment success [39–40].
However, findings in the current study showed that short term outcomes were comparable at one-month post-therapy. However, at one-year follow-up, non-smokers had favorable results when compared to both groups of smokers. Interestingly, E-smokers showed persistent inflammatory outcomes compared to cigarette smokers in gingival color and consistency. This unexpected finding may suggest that specific components in smoking are responsible for reduced blood flow and inflammatory responses in comparison with vaping as supported by previous observations provided by de Waal et al., .
As for plaque accumulation, the plaque index was higher in the group of non-smokers in comparison with the other two groups at baseline. Nevertheless, the significant clinical improvement observed in the three groups noted through one month, decreased slightly after six months and one year follow up but maintained in a lesser amount compared to baseline. The prevalence of BOP showed improvement as well after the treatment. However, it can be noticed that changes were more among non-smokers compared with other smoking groups due to the vasoconstrictive effect of nicotine and other smoke by-products as well as heat on blood vessels and capillaries . Finally, mean PD reduced among non-smokers and cigarette smokers in all the four intervals, while in E-smokers, this reduction had relapsed after six months.
In regards to salivary biological biomarkers which can give a depth vision to the systemic biologic response to different levels and fluctuations of inflammation, MMP-8, IL1 β and IL-6 have shown statistically significant decrease after one month of the treatment from the baseline. However, their values raised marginally at sixth month and one year after the treatment having more raise among E-smokers followed by cigarette smokers and non-smokers. This observation is in line with several previous studies, as for instance, Al-Sowygh et al.  in a case-control study reported higher levels of MMP-8 in smoking groups when compared with non-smoker. Furthermore, in another case-control study by Abduljabbar et al.,  a significantly increased level of IL-1 β and IL-6 in the peri-implant sulcus fluid was observed among smokers’ group in comparison to the non-smokers . On the other hand, all study groups revealed increase values of TIMP-1 throughout the treatment period and demonstrating the highest values among non-smokers and least among E-smokers. In contrast, these values again showed some relapse through long term follow up, especially in the E-smoking group.
These changes in biological markers confirm the clinical presentations among the three groups along the period of the study, proving that non-smokers group has the best response to peri-implantitis treatment compared to other groups. Results proposed in this study confirm that the major source of inflammation and infection is controlled, and preferable biological and clinical response is usually predicted . Moreover, when major risk factors are present such as smoking, the expected treatment outcomes can be more challenging to attain optimal success. Several previous studies had elaborated that even among smokers, successful immediate results can be shown post-treatment of periimplantitis .
Upon authors knowledge, this study is considered the first study to compare peri-implantitis treatment outcomes among cigarette smokers and E-smokers. Since E-smoking is a new and widely spread method among people, the investigations related to the effect of this type of smoking on the periodontium and implant supporting structure are important. Therefore, it is worthwhile to provide investigational efforts to understand how this new type of smoking can act among inflammatory cascades. Moreover, the response in regards to peri-implant and periodontal tissue is to achieve proper treatment protocol and prevention for electrical smokers receiving dental implants.
Limitations of the present study include relatively sample size in each group as well as a lack of information from certain participants regarding the frequency of smoking, number of cigarettes (e.g. Heavy smokers vs light smokers) as well as types of E-cigarettes. Therefore, future researchers are recommended to conduct the study over a large sample size, along with the inclusion of diverse demographic and racial groups to understand different responses and to compare different types of electronic smoking methods. The above recommendations are further important to understand the variations among different products and to have more understanding of their by-products. Finally, it is suggested to compare different approaches to peri-implant treatment based on different peri-implantitis stages and related defects’ properties to achieve a cornerstone of favorable treatment approaches that can achieve long term success.