A study on the changes in attractive force of magnetic attachments for overdenture
PURPOSE Although magnetic attachment is used frequently for overdenture, it is reported that attractive force can be decreased by abrasion and corrosion. The purpose of this study was to establish the clinical basis about considerations and long term prognosis of overdenture using magnetic attachments by investigating the change in attractive force of magnetic attachment applied to the patients. MATERIALS AND METHODS Among the patients treated with overdenture using magnetic attachments in Dankook University Dental Hospital, attractive force records of 61 magnetic attachments of 20 subjects who re-visited from July 2013 to June 2014 were analyzed. Dental magnet tester (Aichi Micro Intelligent Co., Aichi, Japan) was used for measurement. The magnetic attachments used in this study were Magfit IP-B Flat, Magfit DX400, Magfit DX600 and Magfit DX800 (Aichi Steel Co., Aichi, Japan) filled with Neodymium (NdFeB), a rare-earth magnet. RESULTS Reduction ratio of attractive force had no significant correlation with conditional variables to which attachments were applied, and was higher when the maintenance period was longer (P<.05, r=.361). Reduction ratio of attractive force was significantly higher in the subject group in which attachments were used over 9 years than within 9 years (P<.05). Furthermore, 16.39% of total magnetic attachments showed detachment of keeper or assembly. CONCLUSION Attractive force of magnetic attachment is maintained regardless of conditional variables and reduction ratio increased as the maintenance period became longer. Further study on adhesive material, attachment method and design improvement to prevent detachment of magnetic attachment is needed.
Adhesive bonding of titanium nitride-plated stainless steel for magnetic attachments.
The purpose of this study was to evaluate adhesive bonding of resin to titanium nitride ion-plated stainless steel in order for magnetic attachments to survive in the oral environment. Two primers, Cesead II Opaque Primer (CPII) and Metal Primer II (MPII), and one bonding agent, Super-Bond C&B (SB), were used. The surfaces of stainless steel disks were ground and then plated with titanium nitride. After the primer and SB resin were applied, a self-curing resin was bonded to the metal surfaces. Shear bond strengths were determined after 24 h of water storage and after 2,000 thermocycles. Titanium nitride ion-plated stainless steel showed bond strength comparable to the non-plated material. After thermocycling, all specimens of the group no primer/no SB were debonded. The bond strengths of groups CPII/no SB, MPII/no SB and no primer/SB were significantly lower bond strengths than groups CPII/SB and MPII/SB. An appropriate combination of primer and bonding agent should be selected when bonding a magnetic attachment to the denture base.
Law as Palimpsest: Conceptualizing Contingency in Judicial Opinions (forthcoming 2009)
Metaphors create conceptualizations, and for decades legal academics have employed metaphors to shape understandings of legal problems. But no metaphor in current use successfully conceptualizes the contingency of judicial opinions and the complexity of the relationship between opinions and precedent. This Article seeks to fill this void by introducing a new metaphor, the palimpsest, into the realm of legal analysis. A palimpsest is a writing surface that can be cleared away for reuse, like a personal blackboard. What distinguishes a palimpsest from other writing surfaces is that its removed contents do not disappear, but remain, obscured yet recoverable: A writing on a palimpsest never goes away. This Article argues that thinking of judicial opinions as being part of a shared, ever-evolving palimpsest underscores the fact that they are ultimately contingent and serves as a reminder of the multiple levels of interconnectedness between them and the cases they cite. Precedents—like the underlayers of a palimpsest—never go away, and they inform and shape the application of opinions in ways far more significant than simply serving as points of reference. A palimpsestic approach to understanding judicial decisionmaking also helps to explain why even the oldest, most reviled cases remain part of our national psyche—like underlayers of a palimpsest, they can never truly disappear, and their continued presence forces us to grapple with their existence. Finally, considering judicial opinions as part of a shared palimpsest reminds us that even the most troubling opinion is ultimately contingent, its application subject to reexamination and revision by future courts and future generations. Just as such an opinion replaces its precedents, it too will one day be replaced, like each of a palimpsest’s layers. 2 Law as Palimpsest [Vol. __:__ Law as Palimpsest: Conceptualizing Contingency in Judicial Opinions