Mini-implants and narrow diameter implants as mandibular overdenture retainers: A systematic review and meta-analysis of clinical and radiographic outcomes.

This study reviews the clinical and radiographic outcomes of Mini-implants (MI) and Narrow Diameter Implants (NDI) as mandibular overdenture (MO) retainers. Six databases were consulted for clinical studies that evaluated implants with diameter ≤3.5 mm. Data on the MI and NDI for survival and success rate and peri-implant bone loss and were collected and submitted to meta-analysis. Thirty-six studies were included, 24 reporting MI performance and 12 describing NDI results. The MI group comprised data from 1 cross-sectional clinical study, 3 retrospective longitudinal (RL) clinical studies, 13 prospective longitudinal (PL) clinical studies and 7 randomised clinical trials (RCT) with follow-up periods ranging from 1 day to 7 years. Eight studies used conventional loading, thirteen used immediate loading, two studies used both loading types, and one study did not report. The NDI group comprised data from 3 RL clinical studies, 6 PL clinical studies and 3 RCT with follow-up ranging from 6 months to 10 years. Ten studies used conventional loading, 1 study used immediate loading, and 1 study did not report. The average survival rates of MI and NDI studies were 98% and 98%, respectively, while the average success rates were 93% and 96%, respectively. The average peri-implant bone loss after 12, 24 and 36 months was 0.89, 1.18 and 1.02 mm for MI and 0.18, 0.12 and -0.32 mm for NDI. Both MI and NDI showed adequate clinical behaviour as overdenture retainers. The NDI showed a better long-term predictability to retain OM with most studies adopting conventional loading.

How does mandibular bone atrophy influence the masticatory function, OHRQoL and satisfaction in overdenture wearers? Clinical results until 1-year post-loading.

This 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.