Effect of distraction rate and consolidation period on bone density following mandibular osteodistraction in rats.

The high cost of large animal protocols has limited the study of distraction osteogenesis (DO) in the craniofacial region. This study was designed to characterise a rat model for DO with regard to distraction rate and consolidation period. Unilateral mandibular distraction was performed on 129 male Sprague-Dawley rats using an osteotomy from the sigmoid notch to the inferior border of mandible. After a 3-day latency, 12 groups of 8-9 rats underwent distraction for 5 days at four different rates (0, 0.2, 0.4, 0.6mm per day), with three different post-osteotomy sacrifice times (10, 24, and 38 days) and four final predicted distraction lengths (0, 1, 2, and 3mm). Another four groups of rats (N=8 per group) were sacrificed 6 days post-osteotomy, resulting in distraction for 3 days with a predicted distraction length of 0, 0.6, 1.2, 1.8mm. Changes in mandibular morphology were measured from radiographs of disarticluated hemimandibles. The bone density of the regenerate and control sites was measured using microdensitometry calibrated with an epoxy stepwedge. Distraction linearly increased mandibular length, distraction gap width and the area of the distraction gap (P<0.00005). Mandibular length increased by 0.394 mm per distraction rate. Gap width and area increased by 0.67 and 5.8mm(2) per distraction rate, respectively. The increase in length represents only 39.4% of what was predicted, suggesting that compensatory alteration in condylar or mandibular morphology may have occurred. This speculation was further supported by the finding that mandibular length, measured without the condylar landmark, was 53.8% of predicted. During DO and early consolidation, the measures of bone density in the regenerates decreased compared to control for all groups. Thereafter, bone density in the regenerates generally increased in all groups until day 24 (P<0.01), obtaining levels that were comparable to the unoperated side. At both rostral and caudal sites adjacent to the osteotomies, measures of bone density were enhanced over control in all groups, with the rostral site also showing significant increases over time in the sham and the highest distraction groups (P<0.008 and P<0.014). We conclude that this rat model for mandibular distraction osteogenesis provides bone density changes that are consistent with those reported using larger animal protocols.

Lessons learnt from the management of 1500 complex facial fractures.

The lessons learnt from the management of 1500 consecutive patients with complex facial fractures have been analysed. This analysis and the major changes in treatment principles have resulted in dramatic improvement in results. The application of craniofacial surgical principles, extended exposure of the craniofacial skeleton, accurate fracture reduction with rigid internal bony fixation and primary bone graft reconstruction has revolutionised the care of these patients. The reattachment of the soft tissue to the reconstructed skeleton provides the final link in this comprehensive one stage reconstruction. Analysis of results has demonstrated the majority of complications and failures to be due to inadequate exposure and reduction of fractures with bone segments rigidly plated in their unreduced position. Inadequate bone grafting and failure to re-suspend the soft tissue and canthi results in post treatment deformity even if the bony reconstruction is adequate. Adherence to the principles of reconstruction will almost always result in a one-stage correction no matter how severe the initial injury.

Comparison of monounsaturated fatty acids and carbohydrates for reducing raised levels of plasma cholesterol in man.

To compare monounsaturated fatty acids and carbohydrates for actions on lipid and lipoprotein levels from solid-food diets, 10 men were studied on three diets. One diet was high in saturated fatty acids and very high in cholesterol (High Sat + Chol), a second was high in monounsaturates but low in cholesterol (High Mono), and a third was low in fat, high in carbohydrates, and low in cholesterol (Low Fat). All diets were consumed for 6 wk. Compared with the High Sat + Chol diet, the High Mono and Low Fat diets significantly and similarly reduced plasma cholesterol and LDL cholesterol. In contrast, the Low Fat diet significantly lowered HDL cholesterol whereas the High Mono diet did not. Therefore, a solid-food diet rich in monounsaturated fatty acids is equivalent to a low-fat, high-carbohydrate diet for cholesterol lowering but does not reduce the HDL-cholesterol level.

Comparison of three cholesterol-lowering diets in normolipidemic men.

Saturated fatty acids and cholesterol in the diet raise the plasma cholesterol concentration, and a reduction in these constituents is recommended widely. However, there is not general agreement as to which nutrients should replace saturated fatty acids. Several different substitute nutrients are possible. In this study, three cholesterol-lowering diets were compared in nine men living in a domiciliary. On a typical American diet at baseline, cholesterol levels were in the normal range. One replacement diet was high in polyunsaturated fatty acids (High Poly); another had 30% fat and corresponded to the American Heart Association's (AHA) recommended diet for the general public (AHA phase I); the third diet had 20% fat, equivalent to the AHA phase III diet for treatment of hypercholesterolemia. Compared with baseline levels, all diets caused similar reductions in total cholesterol and low-density lipoprotein cholesterol levels, but the High Poly and AHA phase III diets lowered the high-density lipoprotein cholesterol level more than the AHA phase I diet. Thus, for the limited number of patients in this study, the diet recommended for the general public appeared as effective for lowering of cholesterol levels as diets containing more polyunsaturates or more carbohydrates.