Volatile Sulfur Compound Profiles Across Peri-Implant Health, Mucositis and Peri-Implantitis: A Cross-Sectional Study of Factors Associated with Halitosis in Patients with Dental Implants

Background/Objectives: Halitosis is common in patients with dental implants, but the contributions of peri-implant disease and prosthesis design remain unclear. We compared volatile sulfur compound (VSC) profiles across peri-implant health, mucositis, and peri-implantitis and evaluated factors associated with halitosis. Methods: This cross-sectional study included 74 patients with implants in function for at least 12 months, classified according to the 2018 World Workshop definitions (26 health, 25 mucositis, and 23 peri-implantitis). Hydrogen sulfide, methyl mercaptan, and dimethyl sulfide were measured by portable gas chromatography alongside organoleptic scores, tongue coating, salivary flow, and the Halitosis Associated Life-quality Test. A prespecified multivariable regression was complemented by exploratory cross-validated diagnostic, decision-curve, and mediation analyses. Results: Median total VSC increased across health, mucositis, and peri-implantitis, driven primarily by methyl mercaptan. Halitosis prevalence also increased across groups. Cement retention and limited cleaning access were independently associated with higher VSC. An exploratory model combining log-transformed methyl mercaptan, tongue coating, and smoking showed good cross-validated discrimination, and peri-implant bleeding statistically accounted for part of the association between peri-implantitis and VSC, although the cross-sectional design precludes causal inference. Conclusions: Peri-implantitis is associated with a methyl mercaptan-dominant breath profile, and modifiable prosthetic factors are associated with malodour. Whether breath analysis adds to conventional clinical examination was not tested and requires prospective evaluation.