The periodontal ligament, temperature-sensitive ion channels TRPV1-4, and the mechanosensitive ion channels Piezo1 and 2: A Nobel connection.

Teeth are subject to a variety of mechanical forces and vectors. The periodontal ligament (PDL), fibrous tissue that connects the cementum of the tooth to the bony socket, plays a decisive role in transmitting force to alveolar bone via Sharpey fibers, transforming and converting these forces into biological signals. This interaction effects significant osteoblastic and osteoclastic responses via autocrine proliferative and paracrine responses. Recent discoveries of receptors for temperature and touch by the Nobel laureates David Julius and Ardem Patapoutian, respectively have a profound impact on orthodontics. Transient receptor vanilloid channel 1 (TRPV1), initially described as a receptor for temperature, has been proposed to participate in the sensing of force. TRPV4, another ion channel receptor, perceives tensile forces as well as thermal and chemical stimuli. Piezo1 and 2, the classic receptors for touch, in addition to the aforementioned receptors, have similarly been described on PDL-derived cells. In this text, we review the role of the temperature-sensitive ion channels and mechanosensitive ion channels on their biological function and influence in orthodontic treatment.

A brief historical review of flaps and burn reconstruction.

 Thermal, chemical, and electrical injuries contribute to some of the most disabling and deforming wound injury patterns. These challenges, ultimately cared for by burn and reconstructive specialists, require an evolution in the understanding of functional and aesthetic prioritization, 3-dimensional geometric rearrangement of tissues, anatomic considerations of neurovascularized constructs, as well as the development of fundamental technical skills. Flaps, generally defined as tissue constructs, transferred along with a defined vascular supply are considered principle elements in the armamentarium of the reconstructive specialist. The transfer and design of these flaps can augment most tissue type deficits, protect or transfer functional neurovascular and musculotendinous structures, and provide bone and durable soft tissue elements to restore both form and function. The history of flap construct and reconstruction precedes available written text and spans independent cultural, temporal and geographic divides. Several key flaps currently utilized in burn and reconstructive surgery will be reviewed with some historical context provided. A comprehensive review of the history of flaps in reconstructive surgery certainly exceeds the scope of any simplistic chapter or text.