title: Assessment of a Synthetic Type IV Cast and a Resin Polyol Used in the Fabrication of Dental Models.
abstract: OBJECTIVE
  To evaluate the dimensional changes, reproduction of details, and surface roughness of a type IV cast and a resin used to fabricate dental models.
  
  
  METHODS
  Two commercial brands of materials were evaluated: a type IV synthetic cast (Fuji Rock) and a polyol resin (Novox). Twenty samples were obtained from polyvinyl siloxane molds that reproduced the surface of a metal master model standardized according to the American National Standards Institute/American Dental Association specification no. 19. The materials were used according to the manufacturer's instructions and divided into two groups (n = 10). Each mold was photographed immediately after molding and 1 hour after molding. The obtained models were also photographed and measurements were obtained by using Image J software. The paired t-test was used to compare the molding materials and one-way analysis of variance (ANOVA) was used to compare the dimensional changes between the groups at a significance level of 5%.
  
  
  RESULTS
  Statistically significant differences were observed between the models fabricated with the polyol resin and type IV synthetic cast with regard to reproduction of surface details, surface roughness, and dimensional stability (p < 0.05), with the resin providing superior surface detail reproduction and greater dimensional accuracy.
  
  
  CONCLUSIONS
  The polyol resin exhibited superior behavior regarding detail reproduction, surface roughness, and dimensional change compared with the type IV synthetic cast.
authors.affiliation: Student of Master Program of Dentistry, CEUMA University Sao Luis, MA, Brazil.
authors.forename: Stéphanye T
authors.initials: ST
authors.lastname: Carvalhal
authors.affiliation: Department of Postgraduate in Dentistry, CEUMA University, Sao Luis, MA, Brazil.
authors.forename: Mário Gn
authors.initials: MG
authors.lastname: Gomes
authors.affiliation: Department of Prosthodontics, CEUMA University, Sao Luis, MA, Brazil.
authors.forename: Adriana S
authors.initials: AS
authors.lastname: Malheiros
authors.affiliation: Department of Prosthodontics, CEUMA University, Sao Luis, MA, Brazil.
authors.forename: Letícia M
authors.initials: LM
authors.lastname: Gonçalves
authors.affiliation: Department of Postgraduate in Dentistry, CEUMA University, Sao Luis, MA, Brazil.
authors.forename: Matheus C
authors.initials: MC
authors.lastname: Bandeca
authors.affiliation: Department of Postgraduate in Dentistry, CEUMA University, Sao Luis, MA, Brazil.
authors.forename: Etevaldo M
authors.initials: EM
authors.lastname: Filho
authors.affiliation: Professor, Department of Postgraduate in Dentistry, CEUMA University, Sao Luis, MA-65071-380, Brazil, e-mail: rudysd@uol.com.br.
authors.forename: Rudys Rodolfo
authors.initials: RR
authors.lastname: De Jesus Tavarez
mesh_terms: D000704:Analysis of Variance; D003764:Dental Materials; D008422:Materials Testing; D003765:Models, Dental; D011108:Polymers; D011145:Polyvinyls; D012117:Resins, Synthetic; D012833:Siloxanes; D013499:Surface Properties
chemical_list: D003764:Dental Materials; D011108:Polymers; D011145:Polyvinyls; D012117:Resins, Synthetic; D012833:Siloxanes; C024617:polyol; C034183:vinyl polysiloxane
keywords: Calcium sulfate; Cast; Physical properties.