Dental Asia Sep/Oct 2020

Dental Updates SEPTEMBER / OCTOBER 2020 DENTAL ASIA 15 The universal alternative to decontamination with phosphoric acid Phosphoric acid is not only used for etching enamel and dentin surfaces within dental bonding procedures but also frequently as an intra and extra-oral cleaning agent for tooth structure and dental restorations. But is phosphoric acid always the right choice? DIRECT RESTORATIONS Many bonding procedures are performed using self-etch adhesive systems. When applied to the prepared tooth surface, the acidic monomers in the primer and the bond partially remove and modify the smear layer, resulting in a thin hybrid layer. A substantial amount of hydroxyapatite (HAp) crystals remains on the slightly etched surface, enabling both chemical and mechanical adhesion between the adhesive and the dental tissue. If the bonding surface in the cavity is contaminated and the clinician applied phosphoric acid for cleaning and decontamination, it etches the tooth structure, too, resulting in the removal of HAp. It will prevent the desired chemical adhesion, between the bonding system and the tooth, which may lead to compromised bond strength. Hence, cleaning with phosphoric acid may have a negative effect in this context and cannot be recommended. Impressive cleaning results with no adverse effect on the performance of the dental adhesive are obtained with the universal cleaning solution KATANA™ Cleaner. Developed by Kuraray Noritake Dental, it contains an MDP salt of triethanolamine (MDP-TEA), as well as ‘free’ MDP. With a pH of 4.5, KATANA™ Cleaner is neutral, meaning that, unlike phosphoric acid, it does not remove hydroxyapatite from the tooth. However, it does still effectively eliminate any saliva and blood contamination. INDIRECT RESTORATIONS For materials containing glass, such as lithium disilicate and feldspathic porcelain, phosphoric acid is a tried-and-tested agent for removing contamination. It removes deposits produced when etching these materials with hydrofluoric acid. However, routine use of phosphoric acid to remove contamination from indirect restorations may not be wise. Its use on zirconia is not recommendable, as it could inhibit the desired chemical adhesion of phosphate monomers in the bonding agent to the surface of the zirconia restoration. When cementing prosthetics using self- adhesive resin cement like PANAVIA™ SA Cement Universal, or cement that use self-etching primers (e.g. PANAVIA™ F2.0 or PANAVIA™ V5), the use of phosphoric acid on dentin is not recommended for the same reasons as in the case of direct restorations. NO PITFALLS, NO RESTRICTIONS Unlike 35% phosphoric acid, KATANA™ Cleaner is a product that cleans reliably without inducing adverse side effects – independent of the type of tooth structure, kind of restorative material and planned bonding procedure. Hence, it is a universal cleaning solution that allows users to streamline their procedures. ■ Solea all-tissue laser reduces dental aerosols and splatter by up to 99.9% Convergent Dental, Inc., developer of the industry-leading 9.3μm CO 2 all-tissue Solea laser, has announced that Solea reduces dental splatter and aerosols by up to 99.9% compared to traditional handpieces. The finding supports recent guidance provided by the American Dental Association (ADA), recommending dentists to use clinical techniques that “reduce aerosol production as much as possible, as the transmission of COVID-19 seems to occur via droplets and aerosols.” Two different measurement methods produced similar results, confirming that Solea creates between 97% and 99.9% less splatter and aerosols compared to the traditional dental handpiece. Dr Mark Mizner of Commonwealth Dental Group operated the laser and the drill for a series of tests in which extracted human molars were placed in a model of a human head and cut with each of the instruments. “This study confirmed what has been obvious to me since I first started using Solea in my practice,” said Dr Mizner. “There is virtually no splatter with Solea.” Solea utilises 67%-83% less water flow, 74% less air pressure, and cuts without contact, as opposed to drills, which cut by transferring mechanical energy at up to 400,000 rpm. Mr Michael Cataldo, CEO of Convergent Dental, commented, “Solea has always provided a better experience with drill- free, needle-free fillings and blood-free, suture-free surgeries. We are proud to add significantly safer dentistry for both doctors and patients to the list of Solea benefits.” ■