Smokers have a higher chance of developing peri-implant diseases and are therefore
considered an at-risk population. Our aim was to compare peri-implant characteristics
in users of electronic cigarettes (EC), waterpipes (WP), cigarettes (CS), smokeless
tobacco (ST), and non-smokers (non-users of any nicotine and tobacco product; NS).A
systematic search of four electronic databases (PubMed, EMBASE, Web of Science, CENTRAL)
was performed until April 2023, restricted to English language. Thirty-nine observational
studies were included in the qualitative synthesis, of which 32 studies were included
in a Bayesian network meta-analysis. Using a predesigned form, two researchers independently
collected data about marginal bone loss (MBL), probing pocket depth (PPD), plaque
index (PI), bleeding on probing (BOP), modified plaque index (mPI), probing pocket
depth > 4mm (PPD>4), gingival index (GI), peri-implant sulcular fluid (PISF) volume,
and TNF-α and IL-1β levels. QUIPS and CINeMA were used to evaluate the risk of bias
and certainty of evidence.NS had the smallest MBL. Most nicotine-containing product
users had significantly higher MBL (CS, MD:1.34 CrI: 0.85, 1.79; WP, MD:1.58 CrI:
0.84, 2.35; ST, MD:2.53, CrI: 1.20, 3.87) than NS. EC did not show significant difference
compared to NS (MD:0.52 CrI: -0.33, 1.36). In secondary outcomes NS were ranked in
first place. Subset analysis based on smoking habit, implant duration, and maintenance
control revealed no differences in ranking probability.Most nicotine-containing product
users presented worse peri-implant parameters compared to non-smokers, while EC users
did not show significant differences to NS in many outcomes.Alternative nicotine-containing
products are gaining popularity and are often considered less harmful by the general
public compared to traditional cigarettes. This is the first network meta-analysis
comparing users of four nicotine-containing products and non-smokers. This study shows
that CS, WP and ST have a detrimental effect on the overall health of peri-implant
tissues. EC users also presented inferior parameters compared to NS, however, the
difference was not significant in many outcomes. It is essential to educate patients
who are using nicotine-containing products, and to provide proper maintenance and
appropriate cessation support. Well-designed multi-armed studies are needed for direct
comparison of different products, including heated tobacco products. Greater transparency
of confounding factors is needed regarding smoking habit and oral hygiene.
