Mechanical behavior of implant assisted removable partial denture for Kennedy class II

J Tribst,N Santos,J Da Silva,Ao Dal Piva,A Borges,N Ramanzine,R De Araújo

doi:10.4317/jced.56533

Abstract

BackgroundThis study evaluated the mechanical response of a removable partial denture (RPD) in Kennedy Class II according to being associated or not with implants. Material and MethodsFour RPDs were manufactured for a Kennedy Class II: CRPD - Conventional RPD, RPD+1M, RPD+2M and RPD+12M, respectively, signifying implant assisted RPDs with the implant installed in the first molar, second molar, and in the first and second molars. The finite element method was used to determine the most damaged support tooth under compressive load (300N, 10s) and strain gauge analysis was used to evaluate the microstrain. All groups were submitted to a retentive force analysis (0.5 mm/mm, 100kgf). Microstrain and retentive force data were submitted to One-way ANOVA and the Tukey test, all with α=5%. ResultsHigh microstrain was observed in the second premolar adjacent to the edentulous space under compression load (p< 0.01). RPD+12M presented lower microstrain, however being similar to RPD+2M. RPD+1M presented a higher mean value of retentive force, but similar to RPD+12M. FEM showed RPD assisted by implants concentrates less stress in the periodontal ligament. The association of two implants was sufficient to decrease the stress generated in the implants. The most stressed region for the o-ring abutment was the threads, and the group with two implants showed the lowest stress concentration. ConclusionsIn cases of Kennedy Class II, the association of RPD with implants in the molar region is a favorable option for patient rehabilitation, reducing the movement of the direct retainer adjacent to the edentulous space, increasing the removal force and decreasing the stress magnitude in the periodontal ligament. Key words:Removable partial denture, Finite element analysis, Prosthetic dentistry, Implant-assisted RPD, Distal extension RPD considerations.

Highlights

The total loss of teeth has decreased significantly with the advance in preventive dentistry, whereas the number of partially-toothed patients has increased [1]
The Tukey test showed that the use of two implants (RPD+12M) presented a lower mean microstrain value, it was statistically similar to the removable partial denture (RPD)+2M condition. -Removal force Mean values for removal force were affected by the type of prosthesis, according to one-way analysis of variance (ANOVA) (p < 0.001)
The results demonstrated that there is a modification in the mechanical response generated with the association of one or two implants, as well as their installation position

Summary

Introduction

The total loss of teeth has decreased significantly with the advance in preventive dentistry, whereas the number of partially-toothed patients has increased [1]. Prosthesis distal rotation [4] acts as a fulcrum, creating a levering motion and compressing the soft tissues, generating displacement in the distal extension RPD [5] This movement results in unfavorable horizontal forces, facilitating unwanted bone remodeling and possible loss of the supporting teeth [6]. A fluid elastomer positioned between teeth and alveolus (Flexitime Easy Putty; President Light Body; Xantopren L Blue) was used to simulate the periodontal ligament Afterwards, this model was designed to determine an insertion path for the future RPD by the Applegate method [17]. Electrical cables enabled the connection between the strain gauges and the data acquisition apparatus in which the data reading was performed (StrainSmart® Data Acquisition Software, Micro-Measurements) [15,18] This analysis was used to determine which region would present the highest microstrain values in the bone simulator.

Results

Findings

Discussion