No abstract

This in vitro study compared temperature rises during cavity preparation with an Er:YAG laser, Nd:YAP laser, and a high-speed handpiece. Eighteen teeth were sectioned longitudinally and divided into six groups: group 1 was treated with a carbide bur on a high-speed dental handpiece; group 2 was treated with an Er:YAG laser with an energy of 140 mJ, a pulse repetition rate of 4 Hz; and group 3 was treated with an Nd:YAP laser with an energy of 240 mJ, a pulse repetition rate of 10 Hz. In these groups no water cooling was used. Groups 4 to 6 were treated in the same way, but with water spray. Temperature increases were measured at different dentin thicknesses by a microthermocouple attached to the inner side of the pulp chamber. Water cooling was essential to reduce temperature effects in all groups. Nd:YAP laser induced significantly higher temperature rises than Er:YAG or handpiece. Temperature response to the Er:YAG laser and the handpiece seemed to be similar.

Endodontic treatment in dentistry is a delicate procedure and many treatment attempts fail. Despite constant development of new root canal filling techniques, the clinician is confronted with both a complex root canal system and the use of filling materials that are harmful for periapical tissues. This paper evaluates reported studies on biomaterials used in endodontics, including calcium hydroxide, mineral trioxide aggregate, calcium phosphate ceramics and calcium phosphate cements. Special emphasis is made on promising new biomaterials, such as injectable bone substitute and injectable calcium phosphate cements. These materials, which combine biocompatibility, bioactivity and rheological properties, could be good alternatives in endodontics as root canal fillers. They could also be used as drug-delivery vehicles (e.g., for antibiotics and growth factors) or as scaffolds in pulp tissue engineering.

Scientific evidence validating the beneficial effect of loupes in preventing musculoskeletal disorders is very scarce. The aim of this study was to assess the impact of dental loupes on dental students' posture during a preclinical restorative dentistry course. Using a randomized crossover design, this study was conducted at the School of Dentistry, University of Nantes, France, in 2017. Forty students in their second year of dental study were randomly divided into two groups of 20 each: group A used loupes, whereas group B did not. The week after, students reversed configurations (each subject served as his or her own treatment and control group). Students were video‐recorded during cavity preparation. Trunk, head and neck, and upper arm positions were analyzed using continuous scores based on the modified Posture Assessment Instrument. Additionally, cavities were rated, and students completed a questionnaire on their perceptions of the loupes. On a scale on which lower scores indicated better posture, the results showed significantly higher posture ergonomic scores per minute for students without loupes (146.3±6.64 points/min) than with loupes (123.2±6.77 points/min; p<0.05). The majority of the students (32/39, 82%) showed improvements in ergonomic postures with the use of loupes. Trunk, head, and neck were positively impacted by the use of loupes, but not the upper arms. Cavity preparations were not improved by the use of loupes. The questionnaire revealed negative aspects (pain and difficulty adapting) but underlined the perceived positive impact on posture. This study documented the ergonomic advantages and challenges of introducing magnification near the beginning of the dental training program.

Adult skeletal muscle possesses remarkable regenerative capacity that has conventionally been attributed to the satellite cells. These precursor cells were thought to contain distinct populations with varying myogenic potential. Recently, the identification of multipotent stem cells capable of new myofiber formation has expanded the general view on the muscle regenerative process. Here we examined the characteristics of turkey skeletal muscle-derived cell (MDC) populations that were separated according to their adhesion abilities. We sought to determine whether these abilities could be a potential tool for separating cells with different myogenic commitment. Using the preplate technique, we showed that MDCs display a wide range of adhesion ability, allowing us to isolate a marginal fraction with initial adhesion defect. Methodological investigations revealed that this defect represents an intrinsic and well-established biological feature for these cells. In vitro behavioral and morphological analyses showed that late adherent cells (LACs) share several primitive cell characteristics. Phenotypic assessment indicated that LACs contain early stage myogenic cells and immature progenitors of satellite cells, whereas early adherent cells consist mainly of fully committed precursors. Overall, our findings demonstrate for the first time in an avian model that differential MDC adhesion properties could be used to efficiently purify cells with varying myogenic commitment, including immature progenitor cells. This manuscript contains online supplemental material at http://www.jhc.org . Please visit this article online to view these materials.