title: Longitudinal clinical evaluation of undercut areas and rest seats of abutment teeth in removable partial denture treatment.
abstract: OBJECTIVE
  Adequate preparation of abutment teeth for removable partial denture (RPD) rest seats allows appropriate masticatory force transmission, retention, and stability of supporting structures. It follows that careful preparation will be important for the longevity of the rehabilitation. The present study aimed to clinically evaluate rest seats and undercut areas of abutment teeth in RPD wearers after 2 years of use.
  
  
  METHODS
  A total of 193 occlusal, incisal, and cingulum rest seats were evaluated in terms of shape, rest adaptation, wear, caries, fractures, and surface type (enamel, composite resin, or amalgam). Two hundred and fourteen undercut areas were evaluated in terms of surface type (enamel or restoration) and integrity. This study was approved by the Research Ethics Committee of the Federal University of Rio Grande do Norte, resolution 196/1996, protocol number 11/05.
  
  
  RESULTS
  Intact preparations accounted for 92.2% of the total. Application of the Pearson test (p= 0.289) found no statistically significant differences among the materials on which the rest seats were prepared. For the undercut areas, 20.7% of those obtained on restorative material were nonintact. In addition, Fisher's exact test showed a statistically significant difference (p= 0.001) in surface type; enamel surfaces were shown to be 14 times more stable than restored surfaces.
  
  
  CONCLUSIONS
  The results of this study suggest that rest seats are stable, regardless of the material on which they are prepared. Retentive areas were shown to be more stable when they were located in enamel.
authors.affiliation: State University of Rio Grande do Norte. (UERN), Caicó, Brazil. anarafaela.luz@terra.com.br
authors.forename: Ana Rafaela Luz
authors.initials: AR
authors.lastname: de Aquino
authors.forename: Alessandra Oliveira
authors.initials: AO
authors.lastname: Barreto
authors.forename: Luana Maria Martins
authors.initials: LM
authors.lastname: de Aquino
authors.forename: Ângela Maria Fernandes
authors.initials: ÂM
authors.lastname: Ferreira
authors.forename: Adriana da Fonte Porto
authors.initials: Ada F
authors.lastname: Carreiro
mesh_terms: D016009:Chi-Square Distribution; D015331:Cohort Studies; D003188:Composite Resins; D000044:Dental Abutments; D003723:Dental Amalgam; D003743:Dental Enamel; D003832:Denture, Partial, Removable; D006801:Humans; D011446:Prospective Studies; D018709:Statistics, Nonparametric; D013499:Surface Properties; D019246:Tooth Preparation
chemical_list: D003188:Composite Resins; D003723:Dental Amalgam