Increased plaque, calculus, and tartar build-up are some of the worst consequences of braces and orthodontic treatment. Orthodontic brackets and wires act as inadvertent traps that collect food and plaque where bacteria accumulate, and subsequently cause heavy inflammation of the gums, cause pain, and generate subsequent bone loss. Current supplemental oral hygiene aids include floss threaders, “super-floss,” interproximal brushes, and most importantly reinforcing proper oral hygiene habits at every orthodontic visit. However, implementing these strategies often render ineffective due to the increased cost of additional appliances and due to patients’ non-compliance at such a young age and their unwillingness to change their oral hygiene habits.

Prior investigations within the last decade have recently identified arginine, an amino acid, as an active ingredient in oral dentifrices that help prevent dental sensitivity and dental decay. These recent investigations and advancements of amino acids in oral health care products have led to questions of whether they can also help in decreasing plaque that subsequently surround braces once orthodontic treatment starts. A recent study at UCLA (2015) has shown in-vitro bacterial plaque and biofilm that is specifically formed from an orthodontic bracket (Braces). Additionally, different combinations of amino acids were added to evaluate its efficacy in reducing this specific biofilm. Resultant data showed that a combination of the D-forms of arginine, alanine, and lysine proved to be the most effective of any combination tested towards the decrease of the bracket-derived plaque.

This previous study in-vitro study and previous notable associations of amino acids in its positive outcomes in oral health care have led us to investigate whether amino-acids (more specifically arginine, alanine, and lysine) in toothpaste can help prevent and reduce plaque in patients with braces. This will be conducted via two randomized, double-blind clinical trials and its analyses using both objective and subjective measures.

Laser irradiation is a unique technique used to process materials, it is “contactless”, rapid, and highly localized. The scope of this work is focused laser energy interacting with powdered materials that are in one case consolidated before, or in the second case, as a result of, laser irradiation.

Ultrafast laser pulses, pico and femtoseconds long, have provided new ways of processing materials due to either multiphoton absorption or lack of heat affected zones. However, pulsed laser incubation effects, in which the material is heated or ablated at lower laser energy density than expected, is not well understood. The first objective is to characterize the ultra-low laser density machining capability of a high repetition rate (55 MHz) femtosecond laser. The laser energy density ablation thresholds were found for several materials to be two orders of magnitude below single pulse thresholds. Results focus on fine-grained binderless tungsten carbide, which is ultrahard and difficult to machine, especially without the metal binder phase. This relatively unexplored regime of laser ablation is found not ideal for precise machining of ultrahard materials due to the heat affected zones and relatively slow removal rates, however, it forecasts promising ultrafast laser micro-machinability at repetition rates below heat accumulation, which depends on the thermal relaxation time.

In the second case, more commonplace continuous wave laser heating is applied to loosely packed ball-milled metal powders to investigate their usefulness in additive manufacturing. The milled powders are compared to industry-standard atomized powders and are found to be feasibly additively manufactured in terms of size distribution, flowability, and potential grain boundary pinning precipitate benefits. However, questions remain regarding the sintered density and scalability to parts larger than laboratory test dimensions.

The findings forecast ideal repetition rates for ultrafast ablation to be hundreds of kHz, depending on thermal diffusion length and time constant, and that milled powder approaches for additive manufacturing are feasible and could help overcome some of the challenges related to alloy design and residual porosity in atomized powders.