Palatal Vault Depth Influence on the Flexural Strength of Two Heat Cure Acrylic Denture Base Resins: An in vitro Study

Abstract

Complete dentures often fracture during normal masticatory function. The reason could be due to the shape of the palate, i.e. deep, medium or shallow palatal vault. This in vitro study was performed to determine the relationship of palatal vault depth and flexural strength of two different permanent denture base resins. Edentulous maxillary casts of patients were collected from the department of prosthodontics, among these the cast with the deepest palatal vault was selected. The specimens were then subjected for flexural strength on universal testing machine. The results revealed that the denture bases fabricated on medium palatal vault depth were best in the flexural strength and denture bases on shallow palatal vault depth faired the least. Among the resins the denture bases fabricated using high impact heat cure resin, were better than the denture bases fabricated using regular heat cure resin. All these results were statistically significant except the results between the regular heat cure denture bases and high impact heat cure denture bases fabricated on the deep palatal vault depth. Also the comparison of fracture energies of denture bases fabricated on deep palatal vault with high impact heat cure resin to denture bases fabricated on medium and shallow palatal vaults with high impact heat cure resin were not significant. It was also observed that all the specimens have fractured in the midline. Clinical implications Palatal vault depth significantly affected the flexural strength of heat cure resin. The most frequent mechanical failure of heat cure resin is fracture especially at the midline. The denture bases fabricated using high impact heat cure resin had best flexural strength than the denture bases fabricated using regular heat cure resin which reduced the fractures. How to cite this article Reddy BMM, Himabindu M, Padmaja BI, Sunil M, Reddy NR. Palatal Vault Depth Influence on the Flexural Strength of Two Heat Cure Acrylic Denture Base Resins: An in vitro Study. J Contemp Dent Pract 2013;14(6):1131-1136.

The Impact of Notches on the Fracture Strength of Complete Upper Dentures: A Novel Biomechanical Approach

“…Regarding the latter, some researchers have used the formula "fracture energy = ½ × fracture load × deflection", in kgr/cm units (Morris et al, 1985;Reddy et al, 2013;Sowmya et al, 2013). Other researchers avoided calculating the fracture energy, estimating the fracture strength based only on the fracture load measurement (Saraf et al, 2013;Polyzois et al, 1996;Shimizu et al, 2005;Hedzelek & Gaidus, 2006;Al-Kadi et al, 2015).…”

“…The CUD presents uniqueness as a loadable structure due to some distinct features like: lack of symmetry, fluctuating cross-section, complexity of applied loads during normal function in both magnitude and direction, and non-uniformity of load distribution throughout the specimen (Lambrecht & Kydd, 1962;Prombonas et al, 2012;Prombonas et al, 2013;Reddy et al, 2013).…”

“…The deformation of such prostheses leading to fractures has its origin from a complex mechanical phenomenon which is dependent on many factors. The viscoelasticity of edentulous mucosa and its non-uniform thickness, the absence of an exact axis of symmetry, the variation in values and magnitude of loading, the thickness diversity in CUDs, and the torsional deformation of the CUDs during function in coexistence with the bending deflection are some of the mechanical factors that make the study of this issue difficult (Lambrecht & Kydd, 1962;Reddy et al, 2013;Prombonas et al, 2013).…”

“…They measured the fracture strength of the denture acrylic base without artificial teeth. The load is applied on the tissue surface of the denture base midline, in the area that corresponds to the premolar and first molar region (Polyzois et al, 1996;Morris et al, 1985;Saraf et al, 2013;Shimizu et al, 2005;Reddy et al, 2013;Sowmya et al, 2013). However, this method presents several weaknesses (Polyzois et al, 1996;Saraf et al, 2013).…”

“…Despite wide clinical success to date, there has been limited fundamental understanding of the biomechanical consequences induced by surface notches which, among all the above mentioned factors, have a significant effect on the mechanical behavior of denture (Saraf et al, 2013;Morris et al, 1985;Polyzois et al, 1996;Shimizu et al, 2005;Hedzelek & Gaidus, 2006;Seo et al, 2006;Reddy et al, 2013;Sowmya et al, 2013;Al-Kadi et al, 2015). Although numerous studies refers to the contribution of surface notches to the failure of CUDs, there is considerable disagreement among researchers.…”