Assessment of Retention and Resistance Form of Tooth Preparations for All Ceramic Restorations using Digital Imaging Technique.

AIM: This in vitro study evaluated the resistance form of die preparations for all ceramic restorations and, thereby, explored the concept of effective taper and its correlation between the ideal in theory and actual in the clinical situation by analyzing the digital images of the die preparations. MATERIALS AND METHODS: Scanned digital images of 114 die preparations for all ceramic restorations (n = 114) were collected from a dental laboratory. All the images were also analyzed digitally using Adobe Photoshop® software to analyze the degree of taper (angle of convergence) of each preparation and then applied the Zuckerman's circle, and the Lewis perpendicular methods were used to measure the resistance form. RESULTS: For the current study, the overall average degree of taper was found to be 20.9° (range, 2-80°), which is more than what is recommended by most previous studies and also sharply greater than the textbook ideal of 3 to 6°. Mean degree of taper for maxillary was 17.56° (anterior-10.50°, posterior-23.7°), and for mandibular teeth, it was 25.22° (anterior-15°, posterior- 28.45°). Out of the 64 analyzed images of maxillary teeth, 61 presented resistance form, while 3 were without it. Out of the 50 mandibular teeth analyzed, 38 possessed resistance form, whereas 12 were without. All the anterior teeth showed resistance form irrespective of the arch. CONCLUSION: The degree of taper showed a significant relationship with resistance and retention form, which was inversely proportional to each other. The recommended "degree of taper" is not always the clinically achievable as advocated in textbooks, as it is modified by various factors in the actual clinical situation. CLINICAL SIGNIFICANCE: The study provides scientific background regarding the relationship between the degree of taper with resistance and retention form, and the relationship was found to be inversely proportional to each other. The recommended "degree of taper" is not always the clinically achievable as advocated in textbooks, and it is modified by various modifying or limiting factors in the actual clinical situation.

Cost-effectiveness of health systems strengthening interventions in improving maternal and child health in low- and middle-income countries: a systematic review.

Health systems strengthening (HSS) interventions are increasingly being implemented to improve maternal and child health (MCH) services in low- and middle-income countries (LMICs). This study reviews global literature on cost-effectiveness of HSS interventions in improving MCH. A systematic review was conducted. Keywords, based on World Health Organization framework on health systems and prior studies, were applied to search in bibliographic databases and on the web. Articles that estimated cost-effectiveness of HSS interventions in LMICs were included in the analysis. Each of the 24 selected studies from 15 countries was assessed in terms of quality and biases using Cochrane's criteria. Review Manager and an Excel template were used to extract data and synthesize findings. HSS interventions concentrated on the components of service delivery, health financing, human resources and quality improvement. Within each component, there existed diverse strategies to strengthen health systems. Among the 24 studies, 15 were rated as high quality, 5 as medium and 4 as low quality. A majority of studies reported cost per disability-adjusted life year (DALY) averted or cost per quality-adjusted life year (QALY) gained; other studies reported cost per life saved or life year gained. However, studies used mixed perspectives of analyses. Compared with gross domestic product per capita, interventions in studies reporting cost per DALY averted or QALY gained were all cost-effective, including performance-based financing, health insurance and quality improvement. This review shows the diversity of HSS interventions in improving MCH, and their potential cost-effectiveness. However, the different perspectives employed in the studies, costing components included in the analyses, and heterogeneous measures of effectiveness and outputs, made it challenging to compare cost-effectiveness across all studies, calling for more and standardized cost-effectiveness studies. For policy making, it is critical to examine long-term cost-effectiveness of programs and cost-effectiveness of synergistic demand- and supply-side interventions.