Effect of occlusal support alteration on mastication of removable denture wearers

Author(s)

Alfonso Sánchez Ayala

• Document type: Doctoral Thesis
• Press: Piracicaba, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Odontologia de Piracicaba
• Defense date: 2011-12-16

Examining board members

Renata Cunha Matheus Rodrigues Garcia; Fernanda Faot; Maria Beatriz Duarte Gavião; Cinthia Pereira Machado Tabchoury; Adriana Silva de Carvalho

• Advisor: Renata Cunha Matheus Rodrigues Garcia

Abstract

Scientific evidences to determine the influence of rehabilitated occlusal support (OS) on masticatory function are insufficient. The aim of this study was to evaluate the influence of OS on masticatory function of removable denture wearers. Twenty three edentulous subjects (mean age=54.2±8.3 years) were rehabilitated with maxillary complete denture and mandibular removable partial denture (RPD). Five OS conditions were determined through wearing of RPD teeth: full OS (L1-control condition), OS to 1° molar (L2), to 2° premolar (L3), to 1° premolar (L4), and absence of occlusal support (L5). Masticatory performance and efficiency were evaluated by chew of Optocal cubes edged 5.6 mm using 20 masticatory cycles. Masticatory performance was evaluated through median particle size (X50) using the sieve method (0.5 - 5.6 mm mesh). Masticatory efficiency was determined through test food percentage by weight that passed through sieve of 5.6, 4, 2.8 and 2 mm mesh. The number of masticatory cycles effected per minute was defined as chewing rate. Selection chances and breakage functions were evaluated performing one masticatory cycle simultaneously to Optocal cubes edged 8, 4.8 and 2.4 mm. Masticatory cycle pattern was qualitatively analyzed through its trajectory and quantitatively evaluated through maximum openings and areas recorded using kinesiographic. In the first part of work, the impact of each OS condition was evaluated. In a second stage, the adapting to each OS condition were weekly evaluated. Then, variables were measured immediately after determining each condition, and after one week using the prostheses in the same conditions. It was applied ANOVA for repeated measures and Tukey tests, Friedman and nonparametric multiple comparisons tests, and Fisher's exact test to compare the OS conditions between them. ANOVA for repeated measures and Dunnett tests were used to compare the adaptation results at each OS and control conditions (?=0.05). Masticatory performance and efficiency (5.6 mm) gradually decreased (p<0.0001) from L1 (X50 = 5.46 ± 0.64 mm, and 51.21 ± 19.44 %, respectively) to L5 (X50 = 6.24 ± 0.44 mm, and 24.50 ± 15.98 %, respectively). The L4 condition showed lower chewing rate than the L1. Chances to select and break cubes sized 8, 4.8 and 2.4 mm also decreased (p<0.0001) as OS was shortened. Masticatory cycle pattern was similar (p>0.05). Subjects adapted their masticatory performance and efficiency (4 and 2.8 mm) until L3 presenting similar values to control condition (p<0.05). According to sieve 2 mm mesh, subjects also showed adaptation in L4 (p<0.05). Only in L2, subjects presented adaptation for chewing rate, selection chance and breakage function (p<0.05). The sudden reduction of the occlusal support resulted in decreased masticatory performance and efficiency due to deteriorated capacity to select and break the Optocal. However, the evaluated subjects adapted their chewing to shortened dental arches up to premolars (AU)

• FAPESP's process: 08/04365-5 - Effect of alteration on occlusal support in mastication of removable denture wearers
• Grantee: Alfonso Sánchez Ayala
• Support Opportunities: Scholarships in Brazil - Doctorate