Efeito de Overdenture Mandibular Retida por 4 Miniimplantes nos Desfechos Reportados pelo Paciente e Função Oral: Ensaio Clínico Randomizado

Abstract

Objective: The aim of this study was to evaluate the change in outcomes of masticatory performance (MP), maximum bite force (MBF), treatment satisfaction (TS), and oral healthrelated quality of life (OHRQoL) in edentulous patients rehabilitated with mandibular overdentures retained by four titanium and zirconia mini-implants (TiZr). Materials and Methods: Edentulous patients received conventional complete dentures, followed by the placement of four mini-implants (Straumann® Mini-Implant System) in the mandible and conversion of the conventional denture into a mandibular overdenture. Treatment protocols were randomized using a 2x2 factorial design combining different surgical protocols (flapped vs. flapless) and loading protocols (immediate vs. conventional). MP was assessed using a mixing ability test with two chewing gums (one pink and one blue) and colorimetric analysis to measure the level of color mixing (Variability of Hue - VoH). MBF was measured by a digital gnathodynamometer in the posterior and anterior regions. The McGill Denture Satisfaction Questionnaire (MDSQ) and the Oral Health Impact Profile for Edentulous (OHIPEDENT) were used to assess TS and OHRQoL, respectively. Gender, age, ridge morphology, surgical and loading protocols were tested as independent variables. MP, MBF, TS, and OHRQoL tests were performed at baseline and at 3, 6, and 12 months after implant loading. Descriptive analyses, independent samples t-test, and Linear Regression Model with Mixed Effects were used for data analysis. Results: 74 participants were evaluated, with 73 completing the 1-year follow-up. A significant improvement in all evaluated outcomes (MP, MBF, TS, and OHRQoL) was observed at all follow-up times compared to baseline values (p<0.001). The effect size (ES) estimate for changes before and after (12 months - baseline) was, for MP: ES=0.804 (20 cycles) and ES=1.284 (50 cycles); for MBF: ES=1.210 (anterior region) and ES=1.507 (posterior region); for TS: ES=2.71; and for OHRQoL: ES=1.72. In all cases, the magnitude of the effect size was considered large, with d>0.80. Furthermore, the flapless protocol was associated with an improvement in MP at the 3-month follow-up (p=0.004), while less resorbed alveolar ridges were associated with better MP (p=0.038) and higher MBF (p<0.001). Conclusion: The mandibular overdenture protocol using four TiZr mini-implants was effective for TS, OHRQoL, MP, and MBF outcomes in edentulous patients, compared to pre-treatment values. Results also suggest that improvements in masticatory function and bite force are influenced by clinical factors, as better outcomes were observed for flapless surgeries and less resorbed edentulous ridges.