title: Relationship between retention forces and stress at the distal border in maxillary complete dentures: Measurement of retention forces and finite-element analysis in individual participants.
abstract: BACKGROUND
  Although the retention force of maxillary complete dentures has been measured in numerous studies with different devices, the biomechanical mechanism associated with the generation of this retention force cannot be determined.
  
  
  OBJECTIVE
  The purpose of this clinical study was to investigate whether 3-dimensional finite-element analysis can be used to estimate the retention force of maxillary complete dentures.
  
  
  METHODS
  The study included 12 participants (6 men and 6 women, mean 77.5 years of age). Replicas of the maxillary complete dentures of all the participants were made using scanning resin. The denture replicas were scanned using cone-beam computed tomography (CBCT), and 3-dimensional finite-element models were constructed (dentures, mucosa, and jig). The tensile site was located 5 mm anterior from the central point of the denture's posterior border, and the loading site was located at the central point of the central incisor edge and the right first premolar buccal cusp. The load was 10 N and perpendicular to the occlusal plane. One-way ANOVA was calculated to determine any differences in the maximum principal stress value among the 3 sites. The Games-Howell test for multiple comparisons was applied to determine which sites were different. A Spearman rank correlation coefficient was used to determine any correlation between the retention force and maximum principal stress at measurement posterior site, and a Pearson correlation coefficient was used at the central incisor edge and premolar buccal cusp (all α=.05). Comparative investigations of the association between the maximum principal stress generated and the denture retention force were carried out.
  
  
  RESULTS
  The stress distribution of the maximum principal stress at each measurement point was similar for each participant. The maximum principal stress at the posterior site measurement was significantly higher than measurements at the incisor edge and posterior buccal cusp (P<.01). The maximum principal stress the posterior and incisor edge sites were found to be correlated (P<.05).
  
  
  CONCLUSIONS
  This study results suggest that although more factors need to be considered, a 3-dimensional finite-element analysis may be used to estimate the retention force of maxillary complete dentures.
authors.affiliation: Graduate student, Department of Geriatric Dentistry, Showa University School of Dentistry, Tokyo, Japan. Electronic address: ogawa0620@dent.showa-u.ac.jp.
authors.forename: Takamasa
authors.initials: T
authors.lastname: Ogawa
authors.affiliation: Professor, Department of Geriatric Dentistry, Showa University School of Dentistry, Tokyo, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Sato
authors.affiliation: Associate Professor, Department of Geriatric Dentistry, Showa University School of Dentistry, Tokyo, Japan.
authors.forename: Noboru
authors.initials: N
authors.lastname: Kitagawa
authors.affiliation: Assistant Professor, Department of Geriatric Dentistry, Showa University School of Dentistry, Tokyo, Japan.
authors.forename: Momoe
authors.initials: M
authors.lastname: Nakatsu
mesh_terms: D000368:Aged; D003799:Dental Stress Analysis; D003781:Denture Retention; D003827:Denture, Complete, Upper; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D008297:Male; D013314:Stress, Mechanical