Does occlusal morphology of artificial teeth improve chewing of removable dentures wearers? A systematic review and meta-analysis.

Purpose: This systematic review aimed to verify whether anatomic, semi-anatomic, or nonanatomic occlusal morphology of artificial teeth improves the masticatory function of complete or removable partial denture wearers.

Materials And Methods: According to the PICO strategy, six databases and the grey literature were searched to identify randomized (RCT) and non-randomized clinical trials (N-RCT) comparing masticatory function, in terms of masticatory performance and efficiency, and muscle activity as primary outcomes; and patient-reported results (O) in individuals using removable dentures (P) with different occlusal morphologies of artificial teeth (I/C). Masticatory ability, satisfaction with the prosthetic treatment, and oral health-related quality of life (OHRQoL) were evaluated as secondary outcomes. Risk of bias was assessed using the Cochrane risk-of-bias tool for randomized trials (RoB 2.0) for RCT and Risk of Bias for non-randomized studies with intervention (ROBINS-I) for N-RCT studies. Meta-analyses were performed to compare primary outcomes and masticatory ability between the occlusal morphologies of artificial teeth of complete or removable partial dentures (α = 0.05). Certainty of the evidence was verified using the GRADE approach.

Results: Eleven studies (seven RCTs and four N-RCTs) were included. The risk of bias was considered low for two studies, some concerns for five, and high for the last four studies. Meta-analyses showed that removable partial dentures with anatomic artificial teeth improved masticatory efficiency for carrot chewing (MD 6.31; 95% CI [3.39, 9.22], I = 0%). However, masseter and temporal muscle activities increased when removable partial dentures with nonanatomic teeth were used (MD -756.97; 95% CI [-892.25, -621.68], I = 100%). Masticatory ability was not influenced by occlusal morphology during chewing of all foods in complete denture users: Carrot (MD -0.88, 95% CI [-8.98, 7.23], I = 57%); sausage (MD -8.86, 95% CI [-23.05, 5.33], I = 71%); apple (MD -5.78, 95% CI [-28.82, 17.26], I = 87%); and cheese (MD -4.16, 95% CI [-15.14, 6.82], I = 62%). The certainty of evidence for all evaluated outcomes was very low, mainly due to very serious problems found in the parameters of inconsistency, indirectness, and imprecision.

Conclusions: Despite the very low certainty of evidence, the occlusal morphology of artificial teeth influences masticatory function. Anatomic teeth improved the masticatory efficiency and muscle activity of removable partial denture wearers. Nonanatomic teeth increased temporal and masseter muscle activity, which negatively affected chewing in removable partial denture users. However, patients using complete dentures with anatomic and semi-anatomic teeth presented similar masticatory ability.