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Dental Casting Technique↗
Biomedical subjects
J R Mackert
Publications and source records attributed to J R Mackert.
Cariostatic and ultraconservative sealed restorations: nine-year results among children and adults.
The objective of this clinical study was to evaluate the long-term efficacy of placing sealed posterior composite restorations for arresting active caries. The tooth preparation for this bonded and sealed restoration was limited to placing a bevel in the enamel only, without the removal of the carious lesion. The radiographic and clinical performance of these ultraconservative sealed composite restorations placed over caries (CompS/C) was compared over a period of nine years with: 1) ultraconservative, localized sealed amalgam (AGS) restorations with no extension for prevention, and 2) traditional, unsealed amalgam restorations (AGU) with the usual extension for prevention outline form. Sealant retention with > 50 percent to 100 percent of the margins occurred in 64 percent of CompS/C and 82.5 percent of AGS restorations. After nine years the cumulative failure rates were 16 percent for CompS/C, 2.5 percent for AGS, and 17.1 percent for AGU restorations. Thus, the clinical performance of CompS/C restorations was slightly superior to that of the traditional AGU restorations. The AGS restorations were definitely superior to the traditional AGU restorations and to the CompS/C restorations in both children and adults alike. Complete sealant retention over CompS/C and AGS restorations was equivalent between children and adults (P = 0.14 and 0.74, respectively). A higher percentage of open margins in CompS/C restorations was seen, however, in children (17.4 percent) than adults (1.94 percent). This study has shown that Class I caries can be arrested by the CompS/C restoration.
Adolescent↗
Leucite crystallization during processing of a heat-pressed dental ceramic.
This investigation was conducted in an effort to elucidate the mechanism of the strengthening that occurs during processing of a heat-pressed dental ceramic (IPS Empress). The effect of processing on leucite content was determined via quantitative x-ray diffraction. A significant effect of processing was revealed by analysis of variance (P < .0001). Post-hoc comparisons by Student-Neuman-Keuls and Duncan's Multiple Range tests revealed no difference in leucite content after pressing, but the leucite content was significantly higher (P < .05) after a single surface colorant firing. A second colorant firing produced a further significant increase in leucite content (P < .05), but no further increase in leucite content was observed following the remaining colorant and glaze firings. The increase in leucite after firing is consistent with the increase in flexural strength following firing observed by Dong et al in 1992.
Aluminum Silicates↗