Periodontal and Peri-Implant Status Among Users of Different Inhaled Tobacco and Nicotine Products: A Systematic Review.

Background/Objectives: Periodontal and peri-implant diseases are influenced by several risk factors, including smoking. While cigarette smoking (CS) is a well-established risk factor, the impact of heated tobacco products (HTPs), electronic cigarettes (E-Cigs), and waterpipe (WS) remains less clear. This systematic review aimed to update the current evidence evaluating the clinical, radiographical, and inflammatory biomarkers of periodontal and peri-implant status among different untreated adult users of inhaled tobacco and nicotine products. Methods: A systematic search of PubMed/MEDLINE, Scopus, and Cochrane Library was performed for studies published between April 2022 and December 2025. Data were extracted and synthesized qualitatively according to the study protocol (PROSPERO: CRD420261284851). Studies were qualitatively assessed using the Risk-of-Bias in Nonrandomized-I. Results: Thirty-one studies including 3106 subjects were analyzed. CS consistently showed the worst periodontal and peri-implant status, with higher plaque indices, probing depth (PD), clinical attachment level (CAL), marginal bone loss (MBL) and more missing teeth. WS showed parameters comparable to CS and worse than non-smokers, with particularly high plaque accumulation and probing depth, as well as a pro-inflammatory biomarker profile. E-Cigs and HTPs generally exhibited intermediate status; E-Cigs showed increased PD and CAL compared with non-smokers, with elevated bleeding on probing despite a lower gingival index, whereas MBL was notably higher, showing the highest overall values among all smoking categories, exceeding CS. HTPs presented slightly less harmful outcomes than other smokers, but the evidence was limited. Biomarker analysis indicated elevated pro-inflammatory and tissue-destructive markers, particularly in CS and WS. Conclusions: Smoking negatively affects periodontal and peri-implant status, with CS exhibiting the worst impact. E-Cigs and HTPs appear less harmful but are not risk-free. Longitudinal studies are warranted to define long-term effects, particularly on peri-implant status, for which robust evidence was restricted to CS.