A comparative review of epinephrine and phenylephrine as vasoconstrictors in dental anesthesia: exploring the factors behind epinephrine's prevalence in the US.

This review paper delves into the comparative study of epinephrine and phenylephrine as vasoconstrictors in dental anesthesia, exploring their histories, pharmacological properties, and clinical applications. The study involved a comprehensive literature search, focusing on articles that directly compared the two agents in terms of efficacy, safety, and prevalence in dental anesthesia. Epinephrine, with its broad receptor profile, has been a predominant choice, slightly outperforming in the context of prolonging dental anesthesia and providing superior hemostasis, which is crucial for various dental procedures. However, the stimulation of beta-adrenergic receptors caused by epinephrine poses risks, especially to patients with cardiovascular conditions. Phenylephrine, a selective alpha-1 adrenergic agonist, emerges as a safer alternative for such patients, avoiding the cardiovascular risks associated with epinephrine. Moreover, its vasoconstrictive effect may not be as deleterious as that of epinephrine, due to its selective action. This review reveals that despite the potential benefits of phenylephrine, epinephrine continues to dominate in clinical settings, due to its historical familiarity, availability, and cost-effectiveness. The lack of commercially available pre-made phenylephrine dental carpules in most countries, except Brazil, and a knowledge gap within dental academia regarding phenylephrine, contribute to its limited use. This review concludes that while both agents are effective, the choice between them should be based on individual patient conditions, availability, and the practitioner's knowledge and familiarity with the agents. The underuse of other vasoconstrictors like levonordefrin and the unavailability of phenylephrine in pre-mixed dental cartridges in many countries highlights the need for further exploration and research in this field. Furthermore, we also delve into the role of levonordefrin and examine the rationale behind the exclusion of phenylephrine from commercially available pre-mixed local anesthetic carpules, suggesting a need for a responsive approach from pharmaceutical manufacturers to the distinct needs of the dental community.

A periosteum-derived cell line to study the role of BMP/TGFß signaling in periosteal cell behavior and function.

The periosteum is a thin tissue surrounding each skeletal element that contains stem and progenitor cells involved in bone development, postnatal appositional bone growth, load-induced bone formation, and fracture repair. BMP and TGFß signaling are important for periosteal activity and periosteal cell behavior, but thorough examination of the influence of these pathways on specific cell populations resident in the periosteum is lacking due to limitations associated with primary periosteal cell isolations and in vitro experiments. Here we describe the generation of a novel periosteum-derived clonal cell (PDC) line from postnatal day 14 mice and use it to examine periosteal cell behavior in vitro. PDCs exhibit key characteristics of periosteal cells observed during skeletal development, maintenance, and bone repair. Specifically, PDCs express established periosteal markers, can be expanded in culture, demonstrate the ability to differentiate into chondrocytes, osteoblasts, and adipocytes, and exhibit an osteogenic response to physical stimulation. PDCs also engage in BMP and/or TGFß signaling when treated with the activating ligands BMP2 and TGFß-1, and in response to mechanical stimulation via fluid shear. We believe that this PDC line will be useful for large-scale, long-term experiments that were not feasible when using primary periosteal cells. Anticipated future uses include advancing our understanding of the signaling interactions that occur during appositional bone growth and fracture repair and developing drug screening platforms to discover novel growth and fracture healing factors.

A study on in vitro degradation behavior of a poly(glycolide-co-L-lactide) monofilament.

The in vitro degradation behaviors of a poly(glycolide-co-l-lactide) 90/10 monofilament were investigated in phosphate buffer solution at pH 7.4 over a temperature range of 27.5-47.5 degrees C. The property changes of the monofilament with time at different temperatures were evaluated by tensile mechanical test, gel permeation chromatography analysis, and image techniques (optical microscopy, scanning electron microscopy and atomic force microscopy). The interrelationships among material properties, in vitro time and experimental conditions were explored. The results showed that the polymer monofilament gradually lost its tensile strength and molecular weight with increasing in vitro time. The hydrolytic degradation of the monofilaments followed a first order behavior. Higher temperatures accelerated the degradation process significantly. It was found that for a given tensile breaking strength retention (BSR), the dependence of degradation time on temperature could be illustrated by an Arrhenius-type equation, from which the activation energy was derived. Further analysis indicated that there are well-defined relationships between molecular weight and tensile strength, which could be illustrated mathematically. Finally, the microscopic evaluation of the monofilament samples revealed visible changes in morphology on the surface and cross-section area during degradation process. The results from atomic force microscopy showed that the surface roughness of the monofilament tended to increase with the in vitro time.

A bioabsorbable microcatheter for the continuous and direct treatment of surgical sites.

A bioabsorbable microcatheter comprising of a polyglycolideco-lactide microtube and an absorbable braid is developed for the continuous delivery of therapeutic fluids directly to a surgical site. Studies conducted with tissue staining dye and radio-opaque solution using porcine models indicate that infusion of fluids in the wound site is rapid and complete. The tissue reaction to the microtube and braid is generally characterized by minimal to mild chronic inflammation or foreign body reaction that decreases in severity as the material is absorbed. The microtube is considered to be absorbed at 56 days postimplantation while the bulk of the braid is considered to be absorbed by 70 days postimplantation.