A Functional Stress Analysis in the Maxillary Complete Denture Influenced by the Position of Artificial Teeth and Load Levels: an In-vitro Study

Abstract

The fracture of complete dentures fabricated using Polymethyl methacrylate resin constitutes a challenge to the clinician and remains an unresolved problem. To determine whether gradual increase in load or different posterior teeth positions in maxillary denture would influence the pattern of stress. Two groups of maxillary dentures were fabricated with different posterior teeth positions (Group I with teeth on the crest of the ridge; Group II with buccal to the crest of the ridge.) using casts prepared from prefabricated edentulous molds, with 5 dentures in each group. Two strain gauges were cemented on to the midline of each denture, one on the anterior palatal area and other on the posterior palatal area. The dentures were loaded from 0 to 110 N in steps of 10 N, and the strains induced were measured. Differences of the stress magnitudes between the 2 groups were statistically analyzed using Mann-Whitney U test. The anterior palatal area of the maxillary denture was dominated by a tensile stress, which was greater in the group II than in group I. The posterior palatal area was dominated by compressive stress but the outer placement of the maxillary teeth caused a significant decrease in the compressive stress. The high anterior tensile stress with compressive stress in the posterior palatal area during loading may be responsible for denture base fractures that initiate from the anterior palatal area. The buccal placement of posterior teeth may play a role in the fatigue fracture of the maxillary denture.

Investigation of the torsional deformation of the complete upper denture: A pilot study

“…Six identical CUDs were constructed according to a previous methodology, which is briefly described below [2][3][4]. Two commercial molds of edentulous jaws were used: one of the upper jaw and one of the lower jaw (edentulous molds, size 55; Columbia Dentoform, Long Island, New York, USA) [2,3,13].…”

“…Guidelines were drawn on the waxed rims to indicate the position of the ridge crest. The anterior teeth (Upper Anterior, Uhler Dental Supply, Chicago, Illinois, USA) were arranged according to standard procedures [2,3,13,14].…”

“…The posterior teeth (Upper Posterior, 33˚; Uhler Dental Supply) were placed with the central grooves of their occlusal surfaces coinciding with the guidelines, and the occlusal surfaces were arranged according to standard procedures to reproduce the anteroposterior and lateral compensating curves [13,14].…”

“…Before the denture specimens were placed on the load casts, the intaglio surfaces were painted with mediumviscosity silicone (Coltoflax, Coltene/Whaledent, NJ, USA) to simulate the oral mucosa. To ensure that the thickness of the silicone was similar to the average thickness of the masticatory mucosa in vivo, the thicknesses of the die stone were reduced by 2 mm and 1.5 mm in the residual ridges of the maxillary cast and the mandibular cast, respectively, before the placement of the painted specimens [2][3][4]13].…”

Comparative Evaluation of Compressive Bond Strength between Acrylic Denture Base and Teeth with Various Combinations of Mechanical and Chemical Treatments

“…Dentures are usually subjected to considerable variations in stress during function [4]. Debonding and detachment of artificial teeth from the denture base is one of the most common and frequently encountered failures or complications in prosthodontic practice.…”