Faculty Bibliography

As can be seen from this report, multifactorial considerations are often present in an orthodontic case. Office policy considerations regarding interoffice communications should be reviewed periodically as to their sufficiency. Interpersonal communications are vitally important from both a risk management standpoint and also from the perspective of maintaining a good doctor-patient relationship. Practitioners today need to keep a wary eye open regarding all possible treatment alternatives, even bizarre ones, should the clinical situation dictate the need for them. Good recordkeeping and documentation are omnipotent should one have the need to defend one's actions. This applies not only to radiographs, photographs, and treatment charts but to records of third-party conversations as well. The doctrine of informed consent should act as a guideline to what information need be transmitted to the patient, both at the beginning and throughout treatment, as it can often help calm potentially troubled waters. Finally, a little luck never hurt anybody.

Many epidemiologists conducting case-control studies choose to dichotomize their exposure data to make the analysis of the data easier and its presentation more straightforward. The choice of a specific rule for dichotomization can have a large effect on the outcome measure, the odds ratio, although this effect is rarely studied. The authors present a graphic approach for exploring this effect, the quantile-quantile (Q-Q) plot. By examining a Q-Q plot, an investigator simultaneously gains information about the distribution of exposures among cases, the distribution of exposures among controls, and odds ratios at all possible cutpoints and their standard errors. In addition, by finding the slope at each point along the Q-Q curve, it is possible to estimate the rate ratios for each possible value of exposure. The authors view the use of the Q-Q plot as an exploratory tool. It enables the investigator to become more familiar with the data and check for irregularities such as outliers, nonlinearities, or nonmonotonic dose-response curves, and idiosyncratic variations of the odds ratio. The authors present an example evaluating the risk of low birth weight as a function of mother's age for Boston births in 1984.

Midgestation fetal wound healing is characterized by healing without fibrosis or scar formation. The mechanisms that underlie this remarkable process are mediated in part through a fetal wound extracellular matrix rich in hyaluronic acid. In this study a newly developed assay was used to determine the hyaluronic acid levels in fetal and adult wound fluid. Adult wound fluid had a rapid increase in hyaluronic acid, which peaked at 3 days and decreased to 0 by 7 days. In contrast levels of hyaluronic acid in fetal wound fluid increased rapidly and remained significantly elevated for 3 weeks. This prolonged presence of hyaluronic acid in the matrix of fetal wounds creates a 'permissive' wound environment that promotes fetal fibroblast movement and proliferation and inhibits cytodifferentiation. Such a matrix environment promotes healing by regeneration rather than by scarring. This observation has therapeutic implications. The prolonged application of hyaluronic acid or hyaluronate protein complexes to wounds in children or adults may modulate healing in a manner that makes the wounds more fetal-like.

We have previously described a model for in utero cleft lip repair in rabbits. Cleft lip and alveolus (CL) were created in fetal rabbits at 24 days gestation (term, 31 days). In this study, postnatal maxillary growth was evaluated in three groups of animals: 1) unoperated controls, 2) unrepaired CL, and 2) repaired CL. The animals were killed at 4, 12, and 26 weeks after birth. Direct cephalometry was performed on dry skulls to evaluate premaxillary width, anterior maxillary length and width, and posterior maxillary width. The results of this study indicate that rabbits that undergo an in utero CL procedure, with or without repair, exhibit no significant decrease in maxillary length and width when compared with controls.

Cardiac myxoma is the most common primary tumor of the heart. This tumor has a gelatinous stroma that is thought to be composed of glycosaminoglycans, the classical acid mucopolysaccharide ground substance. We examined both biochemically and histologically the hyaluronic acid in a case of cardiac myxoma using a newly developed hyaluronic acid-binding protein probe. We observed that hyaluronic acid was localized in the amorphous stroma and occurred at levels 30 times that found in normal atrial septum.

A model for regional muscle-flap coverage of experimental soft tissue defects of complex injuries of the rabbit lower leg is presented. This technique has provided reliable and generous coverage without the difficulty or risk of a free flap procedure, nor the limitations of other local flaps.

A low-powered carbon dioxide laser was used to perform 25 vein grafts (50 anastomoses) on the femoral veins of Sprague-Dawley rats. The patency rate, clamp time, and bleeding time were compared with 50 conventional microvascular vein grafts (100 anastomoses). The patency of the laser-assisted anastomoses (LAVA) was 84 percent, while the conventional vein grafts yielded a 94 percent patency rate. The average clamp time and bleeding time for the LAVA were 47.2 min and 4.88 sec, respectively, while the conventional anastomoses required 57.6 min and had an average bleeding time of 9.44 sec. Histologically, both specimens healed at the same rate, but the laser-assisted anastomoses produced less inflammation and granulation tissue. These results suggest that the laser has potential as a tool for clinical application in microsurgery. In addition, the 94 percent patency rate achieved with the vein interposition graft would suggest that a decrease in the tension across the anastomosis can improve patency.

A fasciovascular pedicle based on the epigastric vessels was developed in a rat model to determine if it could be used as a "universal carrier" to revascularize a new composite flap. The effects of time course, carrier size, and flap ischemia on the revascularization process were studied. A 2.5 x 4-cm or 1 x 4-cm fascial patch pedicled on the vessels was transferred under bipedicled 2.5 x 4-, 6-, or 8-cm abdominal panniculocutaneous flaps. At different time intervals, the flap was raised as an island flap connected only by it vascular bundle and then sutured back in place. The skin perfusion by dermofluorometry and flap survival were both markedly increased on day 5 (p less than 0.001). The wide carrier had a 93% survival area, whereas the narrow carrier had only 71%. The wide carrier induced relatively faster and better revascularization (p less than 0.05). Moderate ischemia promoted revascularization (p less than 0.01). An india ink injection study and histological examination provided visual evidence of revascularization. This fasciovascular pedicle is a promising model for prefabrication of complex new composite flaps and for studying the process of revascularization between the layers. Based on these findings and further investigations, a thin, prefabricated abdominal free flap was successfully transferred for facial resurfacing in humans.