Clinical Research
Assessment of masticatory function of mandibular implant-supported overdenture wearers: A 3-year prospective study

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Abstract

Statement of problem

Wearers of mandibular complete dentures (CDs) often complain of retention and stability problems resulting in poor masticatory function. Evidence suggests that a mandibular overdenture (MOD) stabilized by 2 implants represents the treatment of choice to improve stability and masticatory function. Measurements are needed of the improvement in masticatory function after providing mandibular implant-stabilized overdentures.

Purpose

The purpose of this prospective clinical study was to evaluate the changes in masticatory function from baseline (T0) to 3 months (T1) and 3 years (T2) in participants with MODs and to assess the effect of baseline mandibular bone height and volume on masticatory function after 3 years.

Material and methods

Participants were assessed for masticatory function by using masticatory performance involving paraffin wax cubes as an objective measure and by using masticatory ability involving a questionnaire as a subjective measure. Edentulous individuals presenting for replacement dentures were provided with conventional mucosa-supported prostheses and evaluated for masticatory function after a 3-month settling-in period (baseline measure). Before implant placement, baseline measures of bone height and volume were recorded from cone beam computed tomography (CBCT) images. The prostheses were then converted to implant-stabilized mandibular overdentures while any maxillary prostheses remained supported by the mucosa. Masticatory function was reassessed at 3 months and 3 years after insertion of the mandibular overdentures, and the mean changes from baseline were analyzed with the Wilcoxon signed-rank test. The effect of variables on masticatory function was determined by using multivariate linear regression analyses.

Results

A total of 23 participants were included in the study, with only 1 participant not completing the 3-year assessment. Significant improvement was observed in the masticatory performance (mixing ability index) (P<.01) and masticatory ability score (P<.001) from baseline to 3 months and baseline to 3 years. Bone height and volume had no significant effect on the improvement of masticatory function after conversion to an implant-stabilized mandibular overdenture.

Conclusions

Masticatory function significantly improved after 3 months and was maintained over 3 years in participants with implant-stabilized mandibular overdentures. However, baseline bone height and volume had no significant effect on these changes in masticatory function after 3 years

Section snippets

Material and methods

Human ethics approval was granted by the Ethics Committee of the Faculty of Dentistry, University of Malaya. A prospective longitudinal study design was used. The participants were recruited among those presented between 2008 and 2010 to clinics at the Faculty of Dentistry, University of Malaya requesting complete denture replacement. Inclusion criteria were participants with a minimum of 6 months of experience wearing complete dentures, who were willing to have new dentures, and who gave

Results

A total of 23 participants were initially recruited into the study (mean ±standard deviation [SD] age: 60.74 ±9.94) (Table 1). Almost one-third of the participants were female. Of 23 participants, 17 received telescopic crown attachments, and 6 received LOCATOR attachments. On average, participants had been edentulous for more than 4 years. The mean bone height was 21.46 mm, and the mean bone volume was 8131 mm3 (Table 1). One participant did not return for the 3-year follow-up appointment.

Discussion

The provision of implants to stabilize MODs has been reported to significantly improve masticatory function.5 This finding is consistent with that of the present study, in which a significant improvement in masticatory function was found after conversion to an MOD. Previous studies21, 22 used substrates such as peanuts, carrots, or synthetic substrates such as condensation silicone to assess masticatory performance, but patients with compromised oral conditions are unable to masticate these

Conclusions

Based on the findings of this clinical study, the following conclusions were drawn:

  • 1.

    Masticatory function measured by the mixing ability index and the mastication ability score showed significant improvement over 3 years in participants who converted to MODs.

  • 2.

    Baseline bone height and volume did not have any significant effect on the change in masticatory function after 3 years.

  • 3.

    A large Cohen effect size was preserved for the 3-year duration of the study after conversion to an MOD.

Acknowledgments

The authors thank Dr Kenji Fueki for allowing the use of the facility at Tokyo Medical and Dental University for the calculation of the MAI. Special acknowledgement to the University of Malaya, Kuala Lumpur, Malaysia, for the postgraduate research fund (PG221-2015A) allocation to this project.

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    Supported by the University of Malaya, Malaysia (research grant no.: PG221-2015A).

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