Fig. 1a Figs. 1a-c: Pretreatment patient. Fig. 1b Fig. 1c also used in dentifrices and mouth rinses to provide antimicrobial activity.6 Its limited shelf life created concerns for patients, but in recent years activated chlorine dioxide stored in dual chambers and mixed by the patient immediately before use as a rinse has overcome this problem.7 * Peroxides at low concentrations (≤ 3 percent) have long been recommended to reduce plaque and gingivitis with a good safety record. Disruption of the biofi lm occurs after exposure to hydrogen peroxide-likely a combination of chemical and mechanical processes. The problem that researchers identified in using peroxide for the treatment of periodontal disease is mechanical access to the pocket.8 The rinsing and brushing just doesn't reach deep enough for patients with pocketing greater than 3mm. The challenge is not just getting medication deep into periodontal pockets, but also holding it there long enough for therapeutic 90 APRIL 2018 // dentaltown.com effect. Sealed prescription trays provide effective delivery deep into periodontal pockets (up to 9mm) for concentrations of peroxide as low as 1.7 percent. The oxygenation of the periodontal pockets via a daily 10-minute tray application is hypothesized to modify the microenvironment of the periodontal pocket to modify biofilm regrowth.9 Chlorine-based products have not been used in the tray because of concerns for taste, staining and gingival irritation. Prescription tray therapy Clinical trials have shown that use of hydrogen peroxide, delivered in a sealed prescription tray as an adjunct to scaling, reduces bleeding and pocket depth better than scaling alone.10 Evaluations of refractory maintenance patients from a periodontal office tracked patients for up to five years demonstrating that the addition of sealed prescription tray therapy helped reduce inflammation by 75 percent more thanhttp://www.dentaltown.com