Purpose: To evaluate general dental practitioners' (GDPs) and dental hygienists' (DHs) assessment of prognosis, suggested treatment goals, and estimated number of treatment sessions in patients with varying severity of periodontal disease. Materials and Methods: Seventy-seven GDPs and fifty DHs in a Swedish county participated in a questionnaire study, based on three patient cases: a patient with generalised bone loss but no clinical signs of inflammation (well-maintained); a patient with clinical signs of inflammation and generalised bone loss (periodontitis); and a patient with clinical signs of inflammation but no bone loss (gingivitis). In open-ended questions, the clinicians assessed the prognosis in case of no treatment and proposed treatment goals. Furthermore, based on given fixed-alternative options, they estimated the number of treatment sessions needed for successful management of the condition. Results: Based on a response rate of 94%, the majority of clinicians expected a worsening of the periodontal condition in all three patients (well-maintained: 80%; periodontitis: 94%; gingivitis: 60%). The most common treatment goal in all 3 cases was to improve oral health awareness. The majority of clinicians estimated that the periodontitis case needed slightly more treatment sessions (mean: 3.04, 95% CI: 2.83-3.24) compared to the gingivitis (mean: 1.93, 95% CI: 1.75-2.11) or well-maintained patient case (mean: 1.84, 95% CI: 1.60-2.07). Conclusions: The majority of included clinicians did not perform an individualised risk assessment and did not individually match the number of appointments to the actual periodontal treatment needs of the patient. This may result in overtreatment in some cases and in undertreatment in others, and possibly in suboptimal use of resources. Schlagwörter: clinical decision making, periodontal diseases, periodontitis, prognosis, treatment goals