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Biomedical subjects

J M Paquette

Publications and source records attributed to J M Paquette.

10 recordsLinked to original sources
PubMed2000

Dimensional accuracy of an epoxy resin die material using two setting methods.

STATEMENT OF PROBLEM: Resinous die materials have several important advantages including strength, abrasion resistance, and detail reproduction. Despite these advantages, the shrinkage of resinous die materials during polymerization has limited their widespread acceptance. PURPOSE: This study determined whether a retarded setting reaction could improve the accuracy of an epoxy resin die system, and compared the accuracy of this epoxy resin system with gypsum-based die materials. MATERIAL AND METHODS: Four groups were compared: an epoxy resin manipulated according to manufacturer's instructions (Ivoclar, Schaan, Liechtenstein); the same epoxy resin manipulated to undergo a retarded set; a high-strength high-expansion gypsum (Die Keen); and a resin-filled gypsum (Resin Rock). Ten dies were fabricated for each material from a master metal model using conventional prosthodontic laboratory techniques. The mean of 3 independent measurements recorded using a toolmaker's microscope and digital positioners was used to describe each die. RESULTS: One-way ANOVA revealed that significant differences existed among the materials (P <.0001). Tukey's multiple comparisons testing ranked the dies as follows, from largest to smallest: high-strength high-expansion gypsum, resin-filled gypsum, master metal model, retarded epoxy, and manufacturers epoxy (P <.05). CONCLUSION: Retarding the setting reaction of an epoxy resin die material improved its accuracy. Of the materials tested, retarded set epoxy dies had the least mean dimensional change from the metal master. Epoxy resin die materials had a net shrinkage, but the gypsum-based materials had a net expansion. The epoxy resin materials exhibited more variability than the gypsum-based materials.

Analysis of Variance↗
PubMed1997

Postorthodontic restoration of enamel surface characteristics.

Following orthodontic treatment, the mechanical debonding of brackets often results in damage to the enamel surface of teeth. Loss of natural luster, a roughened surface, and scarring may occur. When scarring occurs, a method for re-establishing the enamel luster and surface characteristics can be instituted by either the restorative dentist or the orthodontist. One method of restoring enamel luster and natural surface characteristics following removal of orthodontic fixtures is through a sequence of enamel polishing. This article discusses logical steps for the restoration of enamel through the utilization of polishing burs and progressive pastes (Proxyt), Ivoclar Vivadent, Amherst, NY) for the final aesthetic orthodontic result.

Composite Resins↗