Patient Satisfaction and Microbial Changes in Complete Dentures.

The restoration of masticatory function and aesthetics is an important aim in dentistry mainly when patients present with extensive tooth loss. The loss of tooth in elderly patients not only impairs the stomatognathic system but also their psychological status and quality of life.so an important criteria's for the success of dentures are patient's expectations and the ability of the denture to replace the lost masticatory efficiency.

The acrylic resin was first used in 1936; it was in that time the best alternative for vulcanized rubber. Where it is characterized by superior characteristics and became the most popular material used since then. Nonetheless, it has some problems such as polymerization shrinkage, weak flexural, lower impact strength, and low fatigue resistance. These often lead to denture failure during chewing or when fall out of the patient's hand. In order to enhance some properties of PMMA, various efforts have been taken including addition of metal wires or plates, fibers, metal inserts, and modification of chemical structure. In recent years, nylon polymer has attracted attention as a denture base material.

Thermoplastic nylon like materials or polyamides were introduced and first used in dentistry in 1950. The polyamide are uniquely characterized by high esthetics especially in removable partial dentures, where retentive components are recommended anteriorly by this material which provide high elasticity we can make the retentive components using the same material and eliminate the metallic clasps.

Polyamides are characterized by low weight and flexibility make it more patient satisfactory and fortunately it has no monomer remnants that may affect patient health and causes allergy. Thermoplastic polyamides have almost no porosity which eliminates water sorption. The technique used for its fabrication is injection molding technique which is more dimension accurate than packing mold technique.

Valplast was initially used just over 50 years ago and has been used in modern dentistry since the mid-fifties. A variation of nylon, which is far more flexible and stronger than poly methyl methacrylate resin, is used in many alternative partial dentures. Valplast flexible dentures are used for full sets of dentures especially in cases of acrylic allergy which represent 20% of the population.

Comparative Evaluation of Impact and Flexural Strength is done to four types of Four Commercially Available Flexible Denture Base Materials. Valplast had the maximum impact strength, so these materials should be used in less undercut areas for long-term interim removable partial dentures.

A study done by investigators who evaluated the surface roughness of four thermoplastic (polyamide: Valplast, Lucitone FRS, polyethylene terephthalate: EstheShot, and polyester: EstheShot Bright) and two conventional acrylic (Heat-polymerizing: Urban, and Pour type auto-polymerizing: Pro-Cast DSP) denture bases by using scratch test. The results showed that the surface of thermoplastic denture base resins was easily damaged compared with polymethyl methacrylate which can cause discomfort to patients and also discoloration.

Complete Dentures Made with High Impact and Flexible Resins were evaluated. There was statistically significant difference for masticatory performance in wet and dry weight values of hard food, but there was no statistically significant difference for masticatory performance in wet and dry weight values of soft food between the conventional and flexible dentures. Though masticatory efficiency and performance were found to be better for patient's dentures made with Polymethyl methacrylate (PMMA), a statistically significant number of patients reported that the flexible dentures were more satisfying than the conventional dentures.

Another study was done to evaluate the patients inflamatory response. patients received acrylic complete denture were associated with significant high levels of proinflammatory salivary cytokines (TNF-α and IL-6) in comparison to their corresponding levels in the thermoplastic polyamide complete denture patients. The high levels of pro-inflammatory salivary cytokines (TNF-α and IL-6) that were found in saliva of control group patients may be linked to their protective effect against tissue inflammation caused by release of residual monomer.

Adherence of Candida albicans to Flexible Denture Base Material was studied and concluded C. albicans has lesser opportunities to adhere on flexible denture than on acrylic resin denture base materials.