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AIMS AND OBJECTIVES: One of the factor which affects the strength of the tooth restored with core material is the property of the material. In clinical situation all such restored teeth are protected by crowns. This study evaluated the strength of different core materials on a compromised tooth structure after restoration with a crown. MATERIALS AND METHODS: Seventy extracted intact human premolars were collected and mounted within a mould using auto-polymerizing resin. The teeth were divided in-to four groups - A, B, C and D. Each group contained 20 teeth except group A with 10 teeth. All the teeth were prepared for full veneer cast crown. Except for the teeth in group: A) extensive class-I cavities were prepared in the teeth of all the groups and restored with; B) composite resin, 3M EPSE Filtek P60; C) Silver reinforced glass ionomer, SHOFU Hi Dense XP and; (D) Resin reinforced glass ionomer, GC Gold Label light cure GIC. All the teeth were restored with cast-metal alloy and exposed to 1.2 million cycles of cyclic loading in a chewing simulator. Subsequently, the teeth that survived were loaded till fracture in the universal testing machine. Fracture loads and type of fractures were recorded. RESULTS: All the specimens survived cyclic loading. The mean fracture strength of the silver reinforced glass ionomer was greater with and without crown (p<0.001). Statistical analysis for the mean fracture load of each specimen showed significant difference between the groups. CONCLUSION: Under the condition of this study, core materials when restored with artificial crown had a significant increase in fracture resistance.
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Fixed replacement of maxillary anterior teeth with an associated bony defect has challenged the restoring dentist with problems like weight of the prosthesis thereby leading to weakening of abutment teeth, difficulty in establishing smile line and mechanical stability. This article describes the management of a patient with such defect with a forgotten prosthesis - the Andrew bridge system, which has a fixed and a removable prosthetic component with retentive clips, which anchors on to a bar spanning the edentulous space. Andrew's bridge system has definite indications and offers immense advantages over the other prosthesis for rehabilitation of cases of such scenario. It addresses the problems aforementioned and provides the optimal retention, mechanical stability, esthetics and comfort to the patient.
RESUMO
INTRODUCTION: The high strength porcelain fused metal crowns have been extensively used in dentistry. However, the fit is the most encountered problems in porcelain fused metal crowns. This mainly depends on the fabrication technique. AIM: The purpose was to compare the internal and marginal fit of laser sintered and conventionally casted Cobalt-Chromium copings. MATERIALS AND METHODS: Twenty stainless steel dies of dimension 15 x 10 mm with 1 mm finish margin were fabricated using CAD-CAM technology. Twenty dies were divided into two groups Group 1 and Group 2 containing 10 samples each. All 20 dies were scanned using LAVA 3M scanner and data were used to fabricate metal copings using Laser sintering technique (Group-1) and Conventional casting technique (Group-2). Copings were cemented onto respective dies and finished and standardized sectioning were made. The sectioned models were scanned under stereomicroscope at 50 x magnification for internal and marginal fit evaluation. RESULTS: Mean and standard deviation of internal and marginal discrepancy of laser sintered copings/conventional cast metal copings was 107.6 ± 10.9µ and 102.1 ± 17.2µ/187.09 ± 11.47 µ and 176.57 ± 25.82 µ respectively. Statistical analysis showed the laser sintered copings have lesser internal and marginal discrepancy than conventional casted copings with p value < 0.001. CONCLUSION: The laser sintered Co-Cr copings showed better internal and marginal fit when compared to that of conventional Co-Cr casted copings.
