Clinical and Microbiological Effects of Smoking on Lithium Disilicate Endocrowns: An Age-Stratified Cross-Sectional...

Background: Smoking alters oral ecological balance, yet its influence on posterior teeth restored with lithium disilicate endocrowns is insufficiently documented. This study assessed the clinical and microbiological impact of smoking on the peri-coronal environment of endocrown-restored teeth, using an age-stratified approach to evaluate cumulative effects. Methods: A cross-sectional study was conducted on 100 adults, equally divided into smokers and non-smokers. Salivary pH, papillary bleeding index, and plaque index were clinically recorded. Subgingival samples collected from endocrown-restored posterior teeth were analyzed using a polymerase chain reaction (PCR) assay targeting major periodontal pathogens. Age-related variation in clinical and microbiological parameters was examined using one-way analysis of variance (ANOVA), followed by Tukey's HSD post hoc test. Results: Smokers showed consistently lower salivary pH and higher plaque accumulation across all age groups. Gingival bleeding was reduced in younger smokers but increased in older individuals. Microbiological analysis identified markedly elevated levels of orange-complex organisms in smokers, including Prevotella intermedia and Fusobacterium nucleatum. Clinically, endocrowns in smokers presented more frequent marginal degradation, localized inflammation, and early signs of recurrent caries. These effects intensified with age. Conclusions: Smoking adversely modifies the peri-coronal biological environment of lithium disilicate endocrowns by increasing acidity, promoting plaque maturation, and supporting dysbiotic microbial communities. Age further amplifies these changes. Considering smoking status and patient age during treatment planning may improve long-term restorative outcomes.