SummaryThis longitudinal clinical study investigated the differences in the masticatory function (MF), satisfaction and oral health‐related quality of life (OHRQoL) between atrophic patients (AP) and non‐atrophic patients (NAP) before and after rehabilitation with mandibular overdenture (MO). Twenty‐six complete denture (CD) wearers were categorised into two groups, according to the mandibular bone atrophy (MBA) degree. MF was evaluated before and after 1, 3, 6 and 12 months of the MO loading via 2 standardised tests: (i) MP, masticatory performance (MP_X50, MPB, ME 5·6, ME 2·8) and (ii) ST, swallowing threshold (time, number of cycles, ST_X50, STB, ME 5·6, ME 2·8). The dental impact on daily living (DIDL) questionnaire measured changes in the satisfaction level and OHRQoL. MP comparisons showed significant difference only for ME 5·6 12 months after MO loading (AP=33·79 ± 23·6; NAP=17·58 ± 20·1). ST presented significant differences before MO loading for: ST_X50 (AP=5·48 ± 0·83; NAP=4·31 ± 1·44), ME 5·6 (AP=53·17 ± 24·71; NAP=29·83 ± 31·45) and ME 2·8 (AP=8·76 ± 6·91; NAP=18·61 ± 10·71). One month after MO loading, NAP performed the ST test 21% faster than AP. After 3 months, significant improvements in STB (AP=4·93 ± 4·82; NAP=2·73 ± 1·27) and ME 2·8 (AP=17·15 ± 10·00; NAP=24·69 ± 7·82) also were observed. DIDL evaluation showed significant differences in the oral comfort domain after 3 months (AP=0·66 ± 0·29; NAP=0·87 ± 0·16) and after 6 months (AP=0·79 ± 0·22; NAP=0·98 ± 0·08), with lower satisfaction levels in the AP. MBA negatively affects the MF mainly the ST. After 6 months, differences between AP and NAP disappeared and ST results were equalised. AP initially has lower satisfaction levels reaching similar levels of satisfaction as NAP after 1 year.