Effect of dental students as instructors on preclinical performance in prosthodontics.

Dental schools continue to have difficulty recruiting and retaining faculty. One approach to augment student learning would be to train and utilize senior dental students as instructors in preclinical courses. This study was undertaken to evaluate the effect of using senior dental students as instructors on the performance of second-year students in two preclinical prosthodontic courses. In the spring term of 2007, four senior dental students and four or five full-time faculty were assigned as instructors for the fixed prosthodontics and complete denture prosthodontics preclinical courses. Each course has previously been conducted with a total of seven to nine faculty instructors. The performance of two groups of second-year students on preclinical projects was compared based upon their source of instruction for the project. The scores for the two groups were compared using the Wilcoxon rank sum tests and the corresponding 95 percent confidence intervals for the median difference in scores for the two instructor types. This study found no significant difference in performance between sophomore students instructed by full-time faculty or those instructed by senior dental students in either the fixed or removable prosthodontics preclinical courses (p>.05). The use of senior dental students as instructors in the preclinical prosthodontics courses may be one option to partially address the shortage of full-time dental faculty.

Small intestinal submucosa versus salt-extracted polyglycolic acid-poly-L-lactic acid: a comparison of neocartilage formed in two scaffold materials.

This study sought to compare differences in neocartilage produced over time from two types of resorbable scaffold materials. One material was entirely synthetic and contained a polyglycolic acid-poly-L-lactic acid matrix (PGA-PLLA). The second scaffold material was bioactive and consisted of a four-layered construct of porcine small intestinal submucosa (SIS). Disk-shaped scaffolds were seeded with canine chondrocytes and implanted into athymic mice for periods of 5, 8, 12, and 24 weeks. Constructs were examined microscopically, assayed for hydroxyproline (HP) and glycosaminoglycan (GAG) content, and collagen typed (I or II) at each time period. Creep indentation tests determined aggregate and shear modulus, permeability, and thickness. Results indicated that SIS maintained its thickness through the first 12 weeks, and then doubled by week 24. The 24-week tissue appeared chondroid-like and possessed high GAG content. Tissues derived from PGA-PLLA scaffolds were lower in HP content than SIS-derived tissues, but type II collagen was demonstrated only in PGA-PLLA-derived tissues at 24 weeks. Mechanical properties were not significantly different for any tissue over time (p > 0.05), but aggregate and shear modulus mean values were consistently higher for PGA-PLLA-derived tissues at nearly every time interval. This, coupled with the presence of collagen types I and II, suggested a more congruent solid phase may be forming within the extracellular matrix of tissues derived from PGA-PLLA scaffolds. Future study is necessary to compare these materials under simulated loading conditions.