Effect of flask closure method on occlusal vertical dimension of complete upper and lower dentures

Sibusiso Rockfort Mthethwa,Lesibana Godfrey Maguga

doi:10.17159/2519-0105/2021/v76no9a1

Sibusiso Rockfort Mthethwa, Lesibana Godfrey Maguga

Open Access

https://doi.org/10.17159/2519-0105/2021/v76no9a1

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Abstract

The movement of teeth during processing of complete dentures disturbs the harmonious occlusal scheme established at the final wax try-in stage. Aims and objectives: to investigate the effect of RS flask closure on occlusal vertical dimensions of complete dentures. The mean occlusal vertical dimension of complete maxillary and mandibular dentures fabricated by the conventional flask closure were measured and compared with that of dentures fabricated by RS flask closure. Design: A pre-test post-test control group experimental design. Methods: Thirty sets of complete maxillary and mandibular wax trial dentures were randomly assigned to experimental groups. Fifteen sets were assigned to conventional flask closure and the remainder to RS flask closure. Compression molding with a long curing cycle was performed for the processing of the dentures. Pre-processing and post-processing occlusal vertical dimensions were determined. Results: The mean occlusal vertical dimensions of wax trial dentures assigned to either group were similar. The data produced substantial evidence to reject the null hypothesis that the post-processing mean occlusal vertical dimensions of both groups were equal. Conclusion: The occlusal vertical dimensions produced by dentures clamped by the RS flask closure were significantly less than those produced by dentures clamped by the conventional flask closure.

Highlights

The movement of teeth during processing of complete dentures disturbs the harmonious occlusal scheme established at the final wax try-in stage
The mean occlusal vertical dimensions of wax trial dentures assigned to either group were similar
The data produced substantial evidence to reject the null hypothesis that the post-processing mean occlusal vertical dimensions of both groups were equal

Summary

Introduction

The movement of teeth during processing of complete dentures disturbs the harmonious occlusal scheme established at the final wax try-in stage. Tooth movement during the laboratory processing of complete dentures is well researched. A recent systematic review combined information from 114 published studies found in PubMed on the factors and variables involved in complete denture processing that can contribute to tooth displacement and the precautions required to minimize it. The incorrect measurement of OVD and resultant provision of insufficient freeway space has been found to lead to teeth clashing; difficulties approximating the lips; discomfort brought about constant stimulation of the muscles; poor appearance; cheek biting; angular chelitis; temporomandibular joint pain; Costen’s syndrome and masticatory inefficiency.[4]

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