Evaluation of dimensional changes in irreversible hydrocolloids and plasters that affect dental prosthetic rehabilitation

Introduction: Poor handling of irreversible hydrocolloids (alginates) and dental plasters by dental offices, laboratory technicians, and dentists causes differences in dimensional accuracy, affecting dental prosthetic rehabilitation. To obtain optimal results, the manufacturers' instructions regarding the handling variables of each product must be followed to the letter. Are there differences in the dimensional accuracy of working models made under different handling variables? Objective: To evaluate the differences in dimensional accuracy of irreversible hydrocolloids and plasters that affect dental prosthetic rehabilitation. Methodology: An experimental in vitro, prospective, cross-sectional, comparative study was conducted. The variables taken into account were: High and low dimensional stability alginate, water-powder ratio of alginate, casting in type III plaster, water-powder ratio of plaster, type of water and pH, imbibition, syneresis, plaster pouring time, type of mixture. The sample size was 40 models, similar to the oral cavity with their respective teeth. A duplicate of the master model was made in alginate and these were then poured and set in type III plaster. The procedure was performed following an established protocol with the manufacturer's instructions and without following any protocol. Then, measurements of three identical pieces of the master model and the duplicate model were taken with a digital caliper. The data obtained were tabulated in Excel, and significant differences between the models were sought according to each of the established variables. Results: The analysis of the information allowed the development of a protocol with the ideal technical instructions for handling these materials in order to optimize the processes and achieve more precise results and adaptability of the prosthetic devices in the short and medium term.