Effect of High Molecular Nano-Chitosan Addition on The Impact Strength of Heat Polymerized Polymethyl Methacrylate Denture Base Resin

Abstract

Abstract-Tooth extraction to overcome the functional and aesthetic outcomes has become an issue in orthodontic treatment. Tooth size discrepancy was determined through a Bolton analysis. Overall Bolton ratio has changed after the tooth extraction, and affected by different extraction. The aim is to determine the effect of premolar extraction to overall Bolton ratio in Class II malocclusion. Subject was 40 patients with Class II malocclusion in accordance with the inclusion criteria. Measurements performed directly on 12 maxillary and mandibular teeth using an electronic digital caliper. The initial overall Bolton ratio was calculated on the whole samples and continued with several hypothetical extractions. After that, the calculation of the overall Bolton ratio after hypothetical extractions were done and the results were statistically tested to see the effect of the premolar extraction on overall Bolton ratio in Class II malocclusion. The initial overall Bolton ratio consisted of small overall Bolton ratio (86.27±3.19) the number of 7 subjects (17.5%), normal overall Bolton ratio (91.63±1.19) with the number of 23 subjects (57,5% ) and large overall Bolton ratio (95.65± 2.47) with the number of 10 subjects (25%). Wilcoxon test showed the effect of premolar tooth extractions on overall Bolton ratio in Class II malocclusion (p=0.001). Overall Bolton ratio shifted significantly into the normal Bolton ratio were observed in the combination of maxillary first premolar and mandibular second premolar extractions, while the maxillary first premolar extraction increased the overall Bolton ratio. Premolar tooth extraction affects the overall Bolton ratio in Class II malocclusion.

The Application of Chitosan Nanostructures in Stomatology

“…Dropwise negatively charged TPP solution was added to an homogeneous CS solution and stirred to obtain nano-CS. The ionic bond formed between TPP and CS strengthens the nano-CS matrix [ 55 , 61 ]. CS can interact with SF through hydrogen bonds to promote the transformation of SF conformation from a random coil to a β-sheet structure, forming a film, which is important in tissue engineering [ 62 ].…”

“…Owing to its small size, nano-CS can increase the surface area and charge density to form a physical and chemical combination between massive molecules and the CS effective chain. The formation of ionic bonds between CS itself and between CS and other polymers creates a continuous three-dimensional structure that increases the mechanical strength of polymers and can withstand a certain degree of force and pressure [ 61 , 124 ].…”

“…To improve the poor mechanical properties of heat-polymerized polymethylmethacrylate (PMMA), a popular denture base material, researchers often add additivest [ 134 ]. The addition of nano-CS increased transverse strength, impact strength, and color stability [ 61 , 135 , 136 ]. The transverse strength increased the tension of the denture base, resulting in cracks in the denture base [ 137 ].…”

“…However, 1% nano-CS was the ideal concentration of transverse strength, impact strength, and color stability for high-viscosity CS solutions with different densities [ 135 , 136 ]. In the modified materials containing 1.5% nano-CS, it was difficult for the nano-CS to diffuse into small voids in PMMA, resulting in relatively few physical and chemical bonds, eventually causing decreased transverse strength [ 61 , 135 ]. Nano-CS decreases porosity, affecting the density and strength of the material [ 61 ].…”

“…In the modified materials containing 1.5% nano-CS, it was difficult for the nano-CS to diffuse into small voids in PMMA, resulting in relatively few physical and chemical bonds, eventually causing decreased transverse strength [ 61 , 135 ]. Nano-CS decreases porosity, affecting the density and strength of the material [ 61 ]. Meanwhile, the membranous porosity of CS decreases with increasing concentrations of CS [ 61 ].…”