Muscular activity may improve in edentulous patients after implant treatment

Data sourcesMedline via Pubmed and the Cochrane Library were searched from January 1980 to September 2013. This was complemented by a manual search of the magazines Deutsche Zahnaerztliche Zeitung, Quintessenz, Zeitschrift für Zahnärztliche Implantologie, Schweizerische Monatszeitschrift and Implantologie. Additionally, the list of reference s of all selected full-text articles and related reviews were further scrutinised for potential included studies in English or German.Study selectionThree review authors independently searched for clinical trials that assessed the muscular activity in the intervention groups: edentulous patients treated with implant-overdentures (IODs) and implant-supported fixed dental prostheses (ISFDPs) and the comparison groups: dentates and edentulous patients treated with mucosa-borne complete removable dental prostheses (CRDPs).Data extraction and synthesisThe primary outcome was the muscular activity (measured by electromyography [EMG]) in masseter or temporalis muscle of the participants during clenching and chewing. The data extraction of each included study consisted of author, year, age range, treatment, number of participants, number of implants inserted, arch treated, opposite jaw, kind and side of the muscles that were measured. EMG gain or loss (unit measured: volt) was considered by using the effect size. For the meta-analyses only the studies that included masseter muscle measured separately from temporalis were considered. Concerning the side of measurement (right and left side measured together or right and left side measured separately), only the dominant type in each category was included.ResultsSixteen articles, out of the initial 646 retrieved abstracts, were analysed. The muscular activity of edentulous subjects increased after implant support therapy during clenching (effect size [ES]: 2.18 [95% confidence interval [CI]: 1.14, 3.23]) and during chewing (ES: 1.45 [95 % CI: 1.21, 1.69]). In addition, the pooled EMG data of IODs and ISFDPs were lower than that of dentate subjects during clenching (ES: -1.01 [95% CI: -1.37, -0.65]). However, the ISFDPs showed higher values than dentates during chewing. Among the edentulous patients the IODs and ISFDPs displayed higher pooled values during clenching (ES: 1.12 [95% CI: 0.7, 1.55]) and chewing (ES: 1.33 [95% CI: -0.57, 2.10]). Furthermore, the muscular activity during chewing correlated with the hardness of the food.ConclusionsEdentulous patients with CRDPs can achieve a greater degree of muscular activity after rehabilitation with implant-supported/retained prostheses during clenching and chewing. During clenching, patients with ISFDPs achieved higher EMG-values than those with dentates. The harder the food, the more muscular activity involved.