Purpose: Oral health is essential in everyone's daily life, and becomes particularly important for those individuals who have been previously drug addicted. The aim of this study was to assess oral health in patients almost at the end of a methadone-detoxification process due to heroin dependency, identifying their treatment needs. Materials and Methods: Seventeen patients, aged between 22 and 51 years, were admitted to the University Hospital of Verona after at least 6 months of being drug-free, except for standard methadone therapy (20 mg/day). Data concerning medical history, social status, drugs and nutritional habits were collected. Restorative conditions and periodontal status were evaluated clinically and radiographically. Results: The duration of illicit drug consumption ranged from 2 to 20 years; methadone treatment duration ranged from 1 to 17 months. A total of 392 teeth were evaluated: 2 patients were diagnosed with periodontitis, whereas dental caries was widespread, affecting most frequently interproximal surfaces of the anterior teeth. Some 185 teeth needed restorations, 15 decayed teeth endodontic treatments, 21 teeth extraction, and 84 teeth were suitable for prosthetic rehabilitations. Caries and periodontal indexes were analysed according to years of heroin consumption (HYC) and months of methadone therapy (MMT), without any statistical differences (p > 0.05) found for both phases. Social and individual factors were investigated in relation with the indexes: no correlations were demonstrated. Regarding irregular food ingestion during HYC, a statistically significant difference (p < 0.05) between the full-mouth visible bleeding on probing index (FM-VBOP) and diet was found. Conclusion: A large carbohydrate intake consequent to methadone therapy increased caries prevalence, despite a more regular diet.