Comparison of Attachment Types in Maxillary Implant-assisted Obturators using Digital Image Correlation Analysis.

AIM: The purpose of the study was to evaluate the stress on the implant and to assess the denture displacement for locator and bar and clip attachment types in implant-assisted obturators. MATERIALS AND METHODS: A maxillary edentulous experimental model with a maxillectomy defect was made along with an opposing edentulous mandibular model with self-cure acrylic. Two endosseous implants were placed in the maxillary model. Corresponding obturator complete denture was fabricated for the maxillary model and a complete denture for the mandibular. The attachments were positioned on the implants in maxillary model, and their sleeve/clip was placed on intaglio surface of the dentures. The mounted articulator was placed on a loading apparatus, and force was incrementally applied to it. The strain and displacement for both the attachment types were measured and compared using Digital Image Correlation (DIC). RESULTS: Locator attachment showed the least stress and minimal displacement as compared to bar and clip attachment. CONCLUSION: The stresses around the implants and displacement of the obturator are affected by the attachment type used. It was found that bar and clip (splinted) showed the maximum stresses around the implant and maximum denture displacement. Locator attachment is the better choice over bar and clip because of its additional retentive features. CLINICAL SIGNIFICANCE: The advantage of using DIC over the conventional strain gauge analysis is that a full-field data of displacement and strain can be obtained instead of getting a mean value on the small surface where the strain gauge is positioned.

Effect of chemical disinfectants and accelerated aging on maxillofacial silicone elastomers: An In vitro Study.

CONTEXT: Maxillofacial prostheses need frequent refabrication due to degradation of color and deterioration of physical properties of the elastomer. AIMS: This study attempted to evaluate the change in color stability, Shore A hardness, and surface roughness of two maxillofacial silicones, A-2186 and Cosmesil M511, when submitted to chemical disinfection and accelerated aging. SETTINGS AND DESIGN: This was a comparative in vitro study. SUBJECTS AND METHODS: The materials included two silicone elastomers - A-2186 and Cosmesil M511 (Factor II Incorporated) - functional intrinsic red pigment and three disinfectants - Fittydent tablet, chlorhexidine gluconate 4%, and neutral soap. The specimens in each group of elastomer were evaluated initially for color, hardness, and surface roughness, which were further divided into subgroups and subjected to disinfection and accelerated aging. The evaluation of color was performed with the help of an ultraviolet reflectance spectrophotometer. Shore A hardness was evaluated using a durometer and surface roughness, with a digital roughness tester followed by scanning electron microscopy analysis. STATISTICAL ANALYSIS USED:: Analysis of variance and Tukey's multiple comparison test were used for statistical analysis. RESULTS: Accelerated aging caused a significant decrease in color, increase in Shore A hardness, and variation in surface roughness in both silicone elastomer groups. Chemical disinfection presented significant changes in color and surface roughness whereas no significant effect on Shore hardness, irrespective of the disinfectant used. CONCLUSIONS: The maxillofacial silicone elastomers presented deterioration in color, hardening, and significant variations in surface roughness when subjected to chemical disinfection and accelerated aging, which provides a valid baseline for future research.