Dentists and dental assistants have an increased risk of getting infected by patients during their daily work, which is especially critical in times of the current COVID-19 pandemic. Causes for infections are manifold but within the dental practice Aerosol, generated by all types of rotating instruments, scalers and powder-water jet devices, is a topic of increasing concern.
The following recommendations are a compilation of studies, guidelines, practical experience and internal KaVo tests to reduce the amount of generated aerosol and to increase the protection of dentists, assistants as well as patients.
This document provides statements with an explanation as well as the reference to the originator of this claim, which are listed at the end of this document. The document covers the topics reduction of infection risk of dentists, assistants and patients, prevention of cross contamination as well as aerosol reduction with all kind of dental instruments.
1. General reduction of infection risk of dentists, assistants and patients
Pay close attention to the infection control guidelines in your country. E.g. vaccinations are of extreme importance regarding the protection of personnel from infectious diseases. Strict hygiene practices should be always enforced.
Study: Jazwauk L, Neumann K, Reitmeier B. Der infektiöse Patient
Ventilation of the treatment room helps reducing the number of germs in the treatment room
Provide the patient with antiseptic mouthwash before starting the treatment. This reduces the number of germs in the oral cavity and therefore reduces the risk of infection of dentists and assistants.
Study: Reitemeier B, Jatzwauk L, Jesinghaus S, Reitemeier C, Neumann K. Effektive Reduktion des Spraynebel-Rückpralls - Möglichkeiten und Grenzen. ZMK 2010:662-673.
Study: Jazwauk L, Neumann K, Reitmeier B. Der infektiöse Patient
Misc.: DAHZ Hygieneleitfaden 12. Ausgabe 2018, Stand 20.03.2018
Study: Peng X, Xu X, Li Y, Cheng L, Zhou X, Ren B. Transmission routes of 2019-nCoV and controls in dental practice
The use of High-Efficiency Particulate Air Room Filters and Ultraviolet Treatment of ventilation system has been proven to decrease the number of air-borne infections in dental clinics.
Study: Harrell S, Molinari J. Aerosols and splatter in dentistry. A brief review of the literature and infection control implications
Study: Peng X, Xu X, Li Y, Cheng L, Zhou X, Ren B. Transmission routes of 2019-nCoV and controls in dental practice
Study: Role of high-efficiency particulate arrestor filters in control of air borne infections in dental clinics
During many dental procedures, the use of a rubber dam will reduce virtually all contamination arising from saliva or blood. If a rubber dam can be used, the remaining source for airborne contamination is from the tooth that is undergoing treatment.
Study: Harrell S, Molinari J. Aerosols and splatter in dentistry A brief review of the literature and infection control implications
Study: Peng X, Xu X, Li Y, Cheng L, Zhou X, Ren B. Transmission routes of 2019-nCoV and controls in dental practice
Study: Sturdevant's Art & Science of Operative Dentistry (Chapter 15)
Wear a face shield with a mask to further prevent the aerosols reaching your eyes, nose or mouth.
Use FFP-2 and FFP-3 masks if aerosols are produced by e.g. using ultrasonic scalers, powder polisher or rotating instruments.
Study: Reitemeier B, Jatzwauk L, Jesinghaus S, Reitemeier C, Neumann K. Effektive Reduktion des Spraynebel-Rückpralls - Möglichkeiten und Grenzen. ZMK 2010:662-673.
Study:RKI: Stand 14.04.2020 gültig solange die bereits ausgerufene Notfallsituation für diesen Bereich beschrieben wird, vorläufig bis zum 31. August 2020. Mögliche Maßnahmen zum Ressourcen-schonenden Einsatz von Mund-Nasen-Schutz (MNS) und FFP-Masken in Einrichtungen des Gesundheitswesens bei Lieferengpässen im Zusammenhang mit der neuartigen Coronavirus-Erkrankung COVID-19
Study: Jazwauk L, Neumann K, Reitmeier B. Der infektiöse Patient
Study: Peng X, Xu X, Li Y, Cheng L, Zhou X, Ren B. Transmission routes of 2019-nCoV and controls in dental practice
Wearing dental magnifying loupes helps correcting your posture, improves visibility, and reduces your tendency to getting closer to the oral cavity. Loups must be used with side shields, if they were not integrated.
2. Prevention of cross contamination
Integrated anti-suck-back valve in coupling prevents back flow of spray water into the water lines (DUWL). This prevents cross contamination by the water line.
Features like KaVo´s MASTERtorque Direct Stop Technology significantly reduce suction of aerosols into the turbine's head through the burr side. This reduces the risk of cross-contamination of Instruments.
Study: KaVo MASTERtorque video
Study: Peng X, Xu X, Li Y, Cheng L, Zhou X, Ren B. Transmission routes of 2019-nCoV and controls in dental practice
3. Aerosol (<50 µm diameter) reduction with all kind of instruments (electrical / turbines / scaler)
External cooling with NaCl, either by a surgical device, external pump or manual syringe, reduces the aerosol due to lack of spray air. Same result is possible by turning off the spray-air line at the treatment unit / electrical motor. As the usual spray (water / air) cooling is deactivated, the speed and cutting force should be reduced to avoid high temperatures at the tooth / bone or tissue. The cooling flow should be 50 ml/min or above. This is applicable when performing e.g. dental restorations.
Temporary at KaVo treatment units with KL 703 / KL 702 / KL 701 motors, spray air can be deactivated by inserting a small rubber ball (KaVo Spare part of the KL703, Mat. Nr. 1.007.7847) in the spray air channel of the motor.
Study: Leung B, Dyson J, Darville B. Coolant effectiveness in dental cutting with air-turbine handpieces
Multiple sprays ports at the instrument reduce the creation of aerosols. Many KaVo MASTER and EXPERT Series Instruments do have three spray ports and support reduced creation of aerosols.
Study: Reitemeier B, Jatzwauk L, Jesinghaus S, Reitemeier C, Neumann K. Effektive Reduktion des Spraynebel-Rückpralls - Möglichkeiten und Grenzen. ZMK 2010:662-673.
Study: Leung B, Dyson J, Darville B. Coolant effectiveness in dental cutting with air-turbine handpieces
Smaller burr diameter and less convex burrs reduce the number of aerosols by a lower circumferential speed.
This means, that when using grinders with pronounced bulges or large working parts (such as the so-called tire-shaped FG grinders) water / blood / saliva is distracted and swirled considerably more.
Study: Reitemeier B, Jatzwauk L, Jesinghaus S, Reitemeier C, Neumann K. Effektive Reduktion des Spraynebel-Rückpralls - Möglichkeiten und Grenzen. ZMK 2010:662-673.
Cleaned spray ports and new burrs/millers/grinders/tips reduce the number of aerosols. Make sure to maintain the Instrument properly and replace burrs/millers/grinders/tips when worn out. More information on KaVo Instruments hygiene and maintenance can be found in the KaVo recommendations of reprocessing KaVo instruments or in the maintenance guideline for KaVo Instruments.
Spread of aerosols are caused partially by turbulences at the burr and the circumferential speed of its surface. This means the slower the burr turns; the less aerosols are produced, and the less aerosols are spread into the room. Remark: This reduction of aerosols is only effective if speed is reduced significantly.
Study: KaVo internal test IQ1 XXX Study: Reitemeier B, Jatzwauk L, Jesinghaus S, Reitemeier C, Neumann K. Effektive Reduktion des Spraynebel-Rückpralls - Möglichkeiten und Grenzen. ZMK 2010:662-673.
New sharp burrs / millers increase cutting efficiency and decrease generated heat at the tooth and treatment time, which leads to a lower number of aerosols per patient. Make sure to check if burrs / millers are worn out before starting the treatment.
Study: Reitemeier B, Jatzwauk L, Jesinghaus S, Reitemeier C, Neumann K. Effektive Reduktion des Spraynebel-Rückpralls - Möglichkeiten und Grenzen. ZMK 2010:662-673.
Link: Sturdevant's Art & Science of Operative Dentistry Edition 7 (chapter 14)
Hand instruments should be used, whenever possible. They are not requiring coolant which reduces aerosols. Example: manual caries excavator instead of a rotating instrument.
Study: Jazwauk L, Neumann K, Reitmeier B. Der infektiöse Patient
Use either water only or air only at the multi-functional syringe to avoid aerosol production. This does not apply when using the water / air combination is a must.
