Table 2. Classification, definition, and statistical usage of observations within the follow-up examinations.

Classification of Observation	Definition	Usage for calculation
Minor complications (MC) ≡CDA Rating Sierra	not detectable by the patient or in a routine dental check-up → call for intervention [e.g. polishing]	Complication function as 1 minus Kaplan-Meier-estimation with the date of MC, AE & SAE
Adverse events (AE) ≡CDA Rating Tango	reported by the patient or visible during check-up → call for intervention [e.g. polishing, reattachment, hygiene instruction, filling]
Severe adverse events (SAE) or loss/ removal ≡CDA Rating Victor	Severely affecting the restoration or tooth → call for biological therapy [e.g. caries removal, endodontic therapy] or technical renewal	Survivor function as Kaplan-Meierestimation with the date of SAE observation or removal