WO2019230952A1 - Apparatus and method for sterilizing water within water supply pipe of dental unit - Google Patents

Abstract

This apparatus is characterized by being provided with: a water supply pipe; and a heating device which is mounted to the water supply pipe and which is for thermally sterilizing water inside the water supply pipe, wherein the heating device controls the number of heterotrophic bacteria in the water inside the water supply pipe at a portion downstream of the heating device to not more than 2000 CFU/mL.

Description

Apparatus and method for sterilizing water in a water supply pipe of a dental unit

The present invention relates to an apparatus and method for sterilizing water in a water supply pipe of a dental unit.

In recent years, in dental units equipped with dental instruments such as tooth-shaving devices (air turbines, micromotors, ultrasonic scalers) and a medical table (chair) where patients sit or lie down and receive medical care, Microbial contamination of water staying inside attracts attention as a big problem. One of the causes of this microbial contamination is that water tends to stay inside elongated tubes that are often used inside dental units, and that biofilms formed by the collection of bacteria tend to adhere. It is considered.

As a conventional technique for solving this problem, a neutral electrolyzed water generating device (for example, see Patent Document 1) that automatically corrects the residual chlorine concentration of dental unit water is used, but it is expensive, and the bacterial existing amount is reduced. It is unclear whether it is effective in reducing the number of heterotrophic bacteria, which has been attracting attention in recent years as an index for grasping more accurately.

In addition, as a means of reducing the number of heterotrophic bacteria in water used in the medical field, for example, setting the temperature control of the artificial dialysate production apparatus line after hot water disinfection to 50 ° C. (Non-patent Document 1) It has been proposed that non-patent literature 2 treats the piping and circulation system of a hand-washing water station in an operating room with hot water of 65 ° C. In Non-patent Document 3, the unit water sampled from a dental unit, in which 3.9 × 10 ⁴ CFU / ml heterotrophic bacteria were detected was heated to 80 ° C. and heat disinfection was performed. It is described that all the bacteria were sterilized.

JP2009-118892

Bulletin of Hokkaido University of Science, 41, 185-191 (2016) Medical examination, 65 (4), 447-452 (2016) Grant-in-Aid for Scientific Research Research Report, Research on In-Hospital Measures in Dental Treatment of Viral Hepatitis Patients and Infectious Patients May 8, 2009

By the way, regarding the number of heterotrophic bacteria in the water staying in the water supply pipe in the general dental unit (that is, the water discharged from the water supply pipe), the inventors have stayed in the water (that is, the discharge place from the water supply pipe). However, there is a tendency to increase as the distance from the water tap increases (Subsidy for Health and Labor Sciences Research Fund, Regional Medical Infrastructure Development Promotion Research Project, 2016 General Research Report Dental Unit Water Supply System Pure Water Purifier Research on the development of). However, Patent Document 1 does not deal with this problem.

In Japan, there is no strict water quality management target setting value in the water supply piping of devices such as dental units, but it is an urgent issue to deal with contamination of water supplied through the interior of the dental unit. . If we can supply water that satisfies the strict water quality management target setting value even at a location away from the water tap in the dental unit, we can provide microbiologically safe water with a scientific basis to dental care. Useful for health and safety management.

The subject of this invention is providing the apparatus and method for disinfecting the water in the water supply piping which can supply the water in which the number of heterotrophic bacteria decreased easily and cheaply also in the location away from the water tap of the apparatus. is there.

The present inventors attach a heater to the water supply pipe of the dental unit, and use a water supply heated to a moderate temperature of about 55 to 75 ° C. by the heater so that the distance from the water tap in the dental unit is increased. The present invention has been completed by succeeding in suppressing the growth of heterotrophic bacteria that cause microbial contamination of water at the locations.

That is, the present invention encompasses the subject matters described in the following sections.
Item 1. A water supply pipe, and a heating device attached to the water supply pipe for sterilizing water in the water supply pipe, wherein the heating device is heterotrophic of water in the water supply pipe downstream from the heating device. An apparatus characterized in that the number of bacteria is 2000 CFU / mL or less.
Item 2. Item 1. The heating apparatus includes a casing capable of storing water in the water supply pipe and a heater provided in the casing, and heats the water in the casing to 50 ° C or higher. The device described.
Item 3. Item 2. The apparatus according to Item 1, wherein the concentration of free residual chlorine in the water supply pipe downstream from the heating device is 0.1 mg / L or more.
Item 4. The apparatus is a dental unit including an assistant unit and a doctor unit, and the water supply pipe is branched into a water supply pipe leading to the assistant unit and a water supply pipe leading to the doctor unit. Item 4. The device according to any one of Items 1 to 3, which is provided at the branching part or upstream thereof.
Item 5. The apparatus according to claim 4, wherein the doctor unit includes an instrument that is in fluid communication with the water supply pipe, and the number of heterotrophic bacteria in the water discharged from the instrument is 2000 CFU / mL or less. .
Item 6. Item 6. The apparatus according to Item 5, wherein the temperature of water discharged from the instrument after 2 minutes of heating at 60 to 70 ° C for 10 minutes by the heating device is 15 to 35 ° C.
Item 7. A method for sterilizing water in a water supply pipe of an apparatus, wherein the water supply pipe is attached to the water supply pipe and is used for heating and sterilizing water in the water supply pipe. A sterilization method characterized in that the number of heterotrophic bacteria in the water is 2000 CFU / mL or less.

According to the sterilization apparatus and method of the present invention, the number of heterotrophic bacteria at locations away from the water tap of the apparatus can be reduced simply and inexpensively. According to the sterilization apparatus and method of the present invention, it is possible to reduce the use frequency or amount of the chemical for sterilizing water in the water supply pipe, which is excellent in safety. The present invention can be incorporated into an existing dental unit at a low cost and is excellent in practicality.

The schematic plan view of the example of a dental unit. The schematic sectional drawing of the example of a heating apparatus. Explanatory drawing which shows the water supply piping in a dental unit, and a water sampling location. The photograph which shows the culture result of heterotrophic bacteria and general bacteria in an aerobic and anaerobic environment. The graph which shows the change of the heterotrophic bacteria in the general dental unit by residual water discharge | emission. Hand: Handpiece water. Moisture: Moisture water. The graph which shows the change of the free residual chlorine concentration in the general dental unit by residual water discharge. Hand: Handpiece water. Moisture: Moisture water. The graph which shows the number of heterotrophic bacteria (CFU / mL) in each general dental unit piping location. (A) Graph from the water tap (P1) to the inside of the operator table (P6). (B) Graph of handpiece (P7). The graph which shows the free residual chlorine concentration (mg / L) in each part of general dental unit piping. The graph which shows the heterotrophic bacteria count (CFU / mL) in the handpiece drainage of the dental unit with a drug washing function. The graph which shows the free residual chlorine concentration (mg / L) in the handpiece discharge water of a dental unit with a drug cleaning function. The graph which shows the influence with respect to the heterotrophic bacteria which exist in the handpiece discharge water by the heating of the water in the water supply piping of a general dental unit. At each heating temperature, the left bar graph is data of unit 1, the central bar graph is data of unit 2, and the right bar graph is data of unit 3. The arrows in the graph indicate samples containing the number of bacteria below the target value of heterotrophic bacteria (2000 CFU / mL). The graph which shows the influence with respect to the temperature of handpiece discharged water and the heterotrophic bacteria in this discharged water by the heating of the water in the water supply piping of a general dental unit. # In the graph indicates a sample containing the number of bacteria below the target number of heterotrophic bacteria (2000 CFU / mL). The graph which shows the influence with respect to the temperature of the handpiece discharge water, and the free residual chlorine concentration in this discharge water by the heating of the water in the water supply piping of a general dental unit.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In the present specification, the general bacterium refers to an aerobic bacterium, facultative anaerobic bacterium that forms a colony in a medium when cultured on a blood agar medium under conditions of 36 ° C. ± 1 ° C. for 7 days, and A general term for obligate anaerobic bacteria.

Heterotrophic bacteria refer to all bacteria that form colonies in the medium when cultured for a long time at a low temperature using a medium containing a low concentration of organic nutrients, specifically 20 ° C using an R2A agar medium. It is a general term for bacteria that form colonies when cultured in 7 days.

FIG. 1 is a schematic plan view of a dental unit 1 according to an embodiment.

The dental unit 1 includes a patient chair 10, dental lighting (not shown), a spit device 15 connected on one side of the patient chair 10, and an assistant unit 20 connected to the spit device 15 via an arm 22. And a doctor unit 30 connected on the other side of the patient chair 10.

The base 2 is disposed below the patient chair 10 and supports the patient chair 10. Various control devices are included in the base 2. Examples of the control device include a hydraulic circuit for moving the patient chair 10 up and down, tilting and standing, and a hydraulic control means for controlling the hydraulic circuit. A foot switch (not shown) is provided on the back side of the patient chair 10 in the base 2, and a practitioner such as a dentist or a dental assistant uses the operation panel (not shown) of the foot switch or the doctor unit 30. It is possible to operate and send a command to the hydraulic control means, and to control the hydraulic circuit so that the patient chair 10 can be lifted and tilted.

The patient chair 10 includes a headrest 11, a backrest 12, a seat portion 13, and a legrest 14.

The spiton device 15 includes a water supply nozzle 16, a bowl-shaped or bowl-shaped spitton 17 for receiving water after the patient has washed and discharged from the oral cavity, a pipe (not shown) for supplying water to the water supply nozzle 16, and a spiton 17 is provided with a water supply / drainage box 18 that accommodates a pipe (not shown) for discharging water flowing through the discharge hole 17a on the bottom surface of 17.

The assistant unit 20 is connected to an assistant table 21 serving as a work table and an assistant table 21, and includes an arm 22 that can rotate the assistant table 21. A base end portion of the arm 22 is pivotally supported by the spitone device 15.

Various instruments 23 can be placed on or suspended on the assistant unit 20, and examples of such instruments 23 include handpieces such as a vacuum, a saliva ejector, and a syringe.

The doctor unit 30 includes an operator table 31 and an operation panel 32 as a work table. Various instruments 33 can be suspended on the doctor unit 30. As such an instrument 33, an air turbine, a micromotor, an ultrasonic scaler, which is a handpiece used by a practitioner during the operation, A syringe three way syringe etc. are mentioned. A part of the instrument 33 is connected to an electric circuit, a water circuit, an air circuit, and the like. The operation panel 32 includes switches (not shown) for operating the various instruments 33. For example, the switch for moving the patient chair 10 up and down and tilting up and water for treatment from the instruments 33 are provided. Examples include a switch for supplying water and stopping water supply. When the practitioner operates various switches, the corresponding various instruments 33 can be appropriately operated via a drive circuit and a control circuit (not shown).

As shown in FIG. 1, the dental unit 1 of this embodiment includes a heating device 40 for sterilizing water in the water supply pipe of the dental unit 1. The heating device 40 is attached to the water supply pipe of the dental unit 1 and functions to heat and sterilize the water in the water supply pipe. The warming device 40 can be accommodated in the water supply / drainage box 18 of the spitone device 15 and can be prevented from being visually recognized during a patient's operation.

FIG. 2 is a diagram showing the structure of the heating device 40 in more detail. The heating device 40 includes a substantially cylindrical (particularly substantially cylindrical) casing 41 that can store water in the water supply pipe 61, a heater 46 provided in the internal space 42 of the casing 41, and a power source for the heater 46. And a thermo switch 47 for switching on / off. The water supply pipe 61 refers to a portion from the water tap 4 to the internal branch P3 in the water supply pipe 60 (see FIG. 3). The casing 41 includes a side member 43, a terminal member 44 and a base end member 45 connected to both ends of the side member 43. The heater 46 is attached to the distal end member 44, and the thermo switch 47 is attached to the proximal end member 45. The base end member 45 includes holes 45 a and 45 b that are in fluid communication with the water supply pipe 61 of the dental unit 1. One hole 45 a flows into the internal space 42 of the casing 41 from the water supply pipe 61 (that is, a heating device). The other hole 45b acts as an inflow port for water in the upstream water supply pipe), and the other hole 45b flows from the internal space 42 of the casing 41 to the water supply pipe 61 (that is, water in the water supply pipe downstream from the heating device). ). Since the internal space 42 defined by the casing 41 is in fluid communication with the water supply pipe 61, the casing 41 and the internal space 42 also constitute the water supply pipe of the dental unit 1.

The thermo switch 47 senses the temperature of the surface of the heating device 40, and when the temperature of the surface of the heating device 40 decreases due to a decrease in the water temperature in the heating device 40 and reaches a certain temperature (first temperature), the thermo switch 47 The switch 47 starts supplying power to the heater 46, and when the temperature of the surface of the heating device 40 rises to a certain temperature (second temperature) due to the rise of the water temperature in the heating device 40, the thermo switch 47 turns on the heater 46. Stop power supply to. Such control by the thermo switch is a well-known technique.

As a target value of 1115002 from Kensui, which was added as a water quality management target setting item in the partial amendment of the ministerial ordinance on the water quality standards set forth by the Ministry of Health, Labor and Welfare The number of settlements formed after 7 days of culture is defined as 2000 CFU / mL or less.

In order to satisfy the standard that the number of heterotrophic bacteria in water at each location in the water supply pipe 60 downstream from the heating device 40 is 2000 CFU / mL or less, the water in the heating device 40 should be heated to 55 ° C or higher. It is preferable to heat to 60 ° C. or higher, more preferably to 65 ° C. or higher. In particular, in order to satisfy the above-mentioned value of the number of heterotrophic bacteria even with water discharged from the instrument 33 including the handpiece having a long distance from the water tap, it is preferable to heat to 55 ° C. or higher. It is more preferable to heat to above, and it is more preferable to heat to 65 ° C. or higher. In addition, if the temperature of the heated water is too high, it is not suitable for the burden on the parts of the dental unit 1 and the use for the practitioner. Therefore, the temperature is preferably 100 ° C. or less, and preferably 90 ° C. or less. More preferably, it is 80 ° C. or less, more preferably 75 ° C. or less. The water in the heating device 40 is preferably heated to a moderate temperature of 55 ° C to 75 ° C, more preferably 60 ° C to 70 ° C. For this reason, for example, it is preferable to set the first temperature to about 60 ° C., the second temperature to about 80 ° C., and preferably the second temperature to about 70 ° C.

The heating time of water by the heating device 40 is not particularly limited, but a shorter time is preferable in terms of the speed and cost of later treatment. The heating time of water by the heating device 40 is preferably 5 seconds or more, more preferably 30 seconds or more, still more preferably 1 minute or more, and even more preferably 2 minutes or more. The upper limit of the heating time is, for example, 60 minutes or less.

The temperature of the water discharged from the instrument 33 including the handpiece after heating by the heating device 40 is preferably 15 to 42 ° C. so that it can be used as it is for the patient's treatment. A temperature of 35 ° C. is more preferable, and a temperature of 18 to 35 ° C. is even more preferable.

Further, the temperature of water discharged from the instrument after 2 minutes of heating at 60 to 70 ° C. for 10 minutes by the heating device is preferably 15 to 42 ° C., and preferably 15 to 35 ° C. Is more preferable, and the temperature is more preferably 18 to 35 ° C. In particular, the temperature of water discharged from the instrument after 2 minutes of heating at 60 to 65 ° C. for 10 minutes by the heating device is preferably 15 to 42 ° C., and preferably 15 to 35 ° C. Is preferable, and 18 to 35 ° C. is more preferable.

Further, the temperature of water discharged from the instrument during 0 to 2 minutes after heating for 10 minutes at 60 to 70 ° C. by the heating device is preferably 15 to 42 ° C., A temperature of 35 ° C. is more preferable, and a temperature of 18 to 35 ° C. is even more preferable. In particular, the temperature of water discharged from the instrument during 0 to 2 minutes after heating for 10 minutes at 60 to 65 ° C. by the heating device is preferably 15 to 42 ° C., It is preferably 35 ° C., more preferably 18 to 35 ° C.

Further, the heating device causes the water in the heating device 40 to be heated to a temperature of 55 ° C. to 75 ° C., more preferably 60 ° C. to 70 ° C., more preferably 60 ° C. to 65 ° C. for 30 seconds or more, more preferably 1 minute or more. Even more preferably, heating is performed for 2 minutes or more, and the temperature of water discharged from the instrument after 2 minutes of heating is preferably 15 to 42 ° C, more preferably 15 to 35 ° C, More preferably, the temperature is ˜35 ° C.

Furthermore, the water in the heating device 40 is heated to 55 ° C. to 75 ° C., more preferably 60 ° C. to 70 ° C., and even more preferably 60 ° C. to 65 ° C. for 30 seconds or more, more preferably 1 minute or more. Even more preferably, heating is performed for 2 minutes or more, and the temperature of water discharged from the instrument during 0 to 2 minutes after heating is preferably 15 to 42 ° C, and preferably 15 to 35 ° C. More preferably, the temperature is 18 to 35 ° C.

According to the tap water quality standard (Article 17-3 of the Water Supply Law Enforcement Regulations) indicated by the Ministry of Health, Labor and Welfare, the standard value of free residual chlorine concentration in tap water is set at 0.1 mg / L or more.

The free residual chlorine concentration of water at each location in the water supply pipe 60 is preferably 0.1 mg / L or more, and in particular, the water is discharged from the instrument 33 including the handpiece having a long distance from the water tap. In order to satisfy the above value of the free residual chlorine concentration even with water, it is preferable to heat the water in the heating device 40 to 45 ° C. or higher, and the preferred heating temperature and heating time are to satisfy the criteria for the number of heterotrophic bacteria. As described above.

Next, the water supply pipe 60 of the dental unit 1 will be described.

As shown in FIG. 3, the water supply pipe 60 of the dental unit 1 of the present embodiment is connected to the water tap 4 and branches through the inside of the water supply / drainage box 18 (see FIG. 1) of the spit device 15. In the present embodiment, the water supply pipe 60 includes a water supply pipe 61 that is a part from the water tap 4 to the internal branch P3, a water supply pipe 62 that is a part from the internal branch P3 to the water supply nozzle 16, and an arm 22 from the internal branch P3. And a water supply pipe 64 extending from the internal branch P3 to the operator table 31 of the doctor unit 30. A practitioner such as a dentist or a dental assistant uses the instrument 23 attached to the water supply pipe 63 of the assistant table 21 and / or the instrument 33 attached to the water supply pipe 64 of the operator table 31 to use the water supply pipe. The treatment is performed using water discharged from the instrument 60 (61, 63, 64) to the instruments 23, 33.

As will be described later, as the distance from the water tap increases in the water supply pipe 60 (in the order of the water sampling points P1, P2, P3, P4, P5, P6, and P7), the heterotrophic water remaining in the water supply pipe 60 is increased. The number of bacteria increases and the free residual chlorine concentration tends to decrease. For this reason, in particular, as the distance from the water tap increases, the water staying in the water supply pipe 60 may not meet the management target value of the number of heterotrophic bacteria of 2000 CFU / mL or less. In addition, tap water standards for free residual chlorine concentrations of 0.1 mg / L or more may not be met. In particular, in the case of gargle water discharged from the Spitton device 15 or water discharged from the instrument 33 of the doctor unit 30 farthest from the water tap (illustrated as a handpiece in the figure), the number of heterotrophic bacteria and free residual chlorine concentration In some cases, neither the above target value nor the reference value is satisfied.

According to the dental unit 1 of the present embodiment, the water in the water supply pipe 60 can be heated to a moderate temperature of 55 ° C. to 75 ° C. by the heating device 40 accommodated in the spittoon device 15. Water quality management target value and liberation of heterotrophic bacteria count in water discharged from dental units such as gargle water discharged through the water supply pipe 62 and handpiece discharge water discharged through the water supply pipes 63 and 64 Water that satisfies all water quality standards for residual chlorine concentration can be supplied easily and quickly. Moreover, since it is not always necessary to use a chemical for heating water, it is also excellent in terms of safety and cost.

The present invention relates to the heating device 40 for heat sterilizing water in the water supply pipe, the dental unit 1 provided with the heating device 40, and the water supply pipe of the dental unit 1 using the heating device 40. Also includes water sterilization methods.

The above embodiment has the following effects.
-According to the dental unit 1 of the present embodiment, the number of heterotrophic bacteria in a location far from the water tap downstream from the heating device 40 can be simply increased by heating the water in the water supply pipe 60 by the heating device 40. Since water that satisfies both the water quality management target value and the water quality standard for free residual chlorine concentration can be supplied, it is easy and quick.
-The prior art has problems such as the impact on the living body and the cost effectiveness of the residual liquid of the disinfecting liquid added to the water system of the dental unit, but according to the dental unit of this embodiment, the water temperature is reduced. Because it is possible to sterilize heterotrophic bacteria only by raising it moderately, it is a safe, inexpensive and effective approach. Also, the possibility of corrosion of the dental unit equipment due to the use of the disinfectant can be eliminated or reduced.
・ Frequent purchase and use of disinfectant is unnecessary. At least the use frequency or amount of the disinfectant can be reduced.
-In the dental unit 1 of this embodiment, since the heating apparatus 40 is provided in the position upstream from the internal branch P3, it is only necessary to provide the heating apparatus 40 in one place, and it branches from the internal branch P3. Water that satisfies both the water quality management target value for the number of heterotrophic bacteria and the water quality standard for the free residual chlorine concentration can be efficiently supplied to all locations of the water supply pipe 60.
-In the dental unit 1 of this embodiment, since the heating apparatus 40 is provided in the position upstream from the internal branch P3, when the practitioner uses the instruments 23 and 33, the temperature of the heated water Has been cooled to a temperature that does not irritate the patient and can be used as is for the procedure.
-Since this embodiment can also install the heating apparatus 40 in the water supply piping of the existing dental unit, it can be incorporated cheaply and safely in all the dental units currently used, versatility, Excellent practicality.

In addition, this invention is not limited to the said embodiment, The following modifications are possible.
-The structure of the heating apparatus 40 is not limited to what was shown in FIG. 2, You may use another structure heater which can heat the water in the water supply piping 60 containing a well-known heater.
-According to the present invention, the number of heterotrophic bacteria may be suppressed to 2000 CFU / mL or less, and the water quality standard having a free residual chlorine concentration of 0.1 mg / L or more may not necessarily be satisfied.
The attachment position of the heating device 40 is not limited to the position of the pipe 61 between the water tap 4 and the internal branch P3, as long as the water quality management target value of heterotrophic bacteria is satisfied, the water supply pipe 60 in the dental unit 1 Can be attached to any location. For example, the heating device 40 may be provided between the water tap 4 and the spittoon device 15, may be provided in the internal branch P3, or may be provided in the assistant unit 20 or the doctor unit 30 or the like downstream from the internal branch P3. It may be provided. Only one installation location is required, and when the practitioner uses the instruments 23 and 33, the temperature of the heated water is cooled to a temperature that does not irritate the patient. 40 is preferably provided in the internal branch P3 or upstream thereof.
-This invention is not limited to the dental unit 1, It can apply also to arbitrary other apparatuses provided with water supply piping, such as a water supply piping of a household water purifier, and a water supply piping of a water storage tank. As a result, the apparatus of the present invention can be used even in sites, regions, and overseas where water pollution is a concern.

Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

1. Collecting water samples from dental units As a general dental unit, three GC Refino units (Product Nos. 00036, 00041 and 00042) have been operating in Tohoku University Hospital since December 2009 and have been operating since September 2012. The two GC Iome Regalo (manufactured Nos. 00672 and 00672). In addition, three Morita Spaceline Spirit V PdW tray systems (manufacturing numbers CH1006, EB1503, and ZC1001) that have been in operation since May 2015 or March 2016 were targeted as dental units with drug cleaning functions.

Before using the general dental unit according to the guidelines in the Hospital Infection Control Practice Manual supervised by the Japan Dental Medical Association, using the symbols in FIGS. 1 and 2, the water supply of the Spitton device 15 for use in the Spitton device In the water for gargle drained from the nozzle 16 (P4) (hereinafter referred to as “garden water”), water for 8 cups of paper, drained from the handpiece (P7) for use in the handpiece ( (Hereinafter referred to as "handpiece water") was subjected to flushing (residual water discharge) by maximum operation for 30 seconds to control water quality. Also, in the dental unit with drug cleaning function, 0.1% hydrogen peroxide solution stays in the chair water supply line for about 2 days every weekend, and before use every morning, all routes such as handpieces are routed to the dedicated flushing tank. Connected and circulated tap water at abundant water flow for 7 minutes to discharge residual water.

For general dental units and dental units with a drug cleaning function, each patient's gargle water and handpiece water (25 mL) before and after residual water discharge are divided into 10 mL and 15 mL in sterile polyethylene tubes. did. The previous 10 mL was used for bacterial testing, and the subsequent 15 mL was used for free residual chlorine concentration measurement.

Also, remove the water supply piping parts of two general dental unit GC company Refino (manufacturing numbers 00036 and 00041) and (1) taps (water sampling point P1), (2) immediately after entering the unit piping from the tap ( Water sampling point P2), (3) Internal branch point (water sampling point P3), (4) Spitton device water supply nozzle (P4), (5) Assistant table inside (water sampling point P5) and (6) Operator Similarly, 25 μmL was sampled from each point inside the table (water sampling location P6) into 10 μmL and 15 μmL in a sterile polyethylene tube (FIG. 3).

2. Methods for culturing and observing heterotrophic bacteria and general bacteria Each water sample was diluted 10 times and 100 times using milliQ water sterilized with a 0.22 μm filter (Millex-GP SLGP033RS, manufactured by Merck Millipore).

Before starting a series of experiments, as a preliminary experiment for examining the culture conditions, heterotrophic bacteria and general bacteria in the residual water sample collected from the handpiece were cultured in an aerobic and anaerobic environment. Aerobic culture was performed in the same manner as the heterotrophic bacteria and general bacteria detection methods described below. Anaerobic culture was performed in a highly anaerobic environment (80% N ₂ , 10% CO ₂ , 10% H ₂ ) using a Thea-type Anaero box (ANB-18-2E, manufactured by Hirasawa).

For the culture of heterotrophic bacteria, 100 μL each of the stock solution and diluted sample is seeded on R2A agar medium (251258, Sakai Nippon BD), and 20 ° C, 7 ° C using a cool incubator (CN-25C-1, manufactured by Mitsubishi Electric Engineering Co., Ltd.). After culturing for a day, the number of colonies on each agar medium was visually counted, and the number of bacteria in each sample (CFU / mL) was calculated.

In culture for detection of general bacteria, 100 μL of the stock solution sample is seeded on CDC sheep blood agar medium (251733, Sakai Nippon BD) and cultured at 37 ° C for 7 days using an incubator (CI-410, Sakai Advantech). Similarly, the number of bacteria (CFU / mL) was calculated.

For heterotrophic bacteria, it was added as a water quality management target setting item in the partial amendment of the ministerial ordinance on water quality standards, and was set as the immediate target value in 1115002 from Kensui. Pass / fail was determined based on the number of colonies formed after culturing at 20 ° C. for 7 days as 2000 CFU / mL or less ”.

3. Measurement of free residual chlorine concentration Free residual chlorine concentration is measured by diethylparaphenylenediamine reagent (free residual chlorine measurement reagent DPD plus, Oyalax Co., Ltd., Cat. # OYWT-11-03) and spectrophotometric residual chlorine measuring instrument. (Photometer CL, Oyalux Co., Ltd., Cat. # OYWT-31) was used according to the attached instruction manual. 10 mL of the 15 mL water sample was dispensed into the sample cell, zero calibration was performed, and then one powdered reagent was dissolved. It was set in the cell insertion part of the measuring instrument and measured after standing for about 30 seconds. Zero calibration and sample cell cleaning with ultrapure water were performed for each sample. Pass / fail was judged based on the standard value (0.1 mg / L or more) of the tap water quality standard (Article 17-3 of the Water Supply Law Enforcement Regulations) indicated by the Ministry of Health, Labor and Welfare.

4). Verification method of heating effect against heterotrophic bacteria in handpiece residual water (in vitro)
Handpiece water samples remaining in the handpiece from the previous day, collected without flushing (residual water discharge) from three general dental units GC Refino (Product No. 00036, 00041, and 00042) in vitro In order to verify the bactericidal effect on heterotrophic bacteria in the sample when heated, the sample was treated as follows.

The remaining water sample was dispensed in 5 ml each into a 15 ml sterile conical tube. In a small dry incubator equipped with an aluminum block (BSR-M002, manufactured by Bio Medical Science), the above 1. After setting the conical tube containing the water sample and the same conical tube containing the same amount of tap water, heating was started. A mercury thermometer is set in the conical tube containing tap water, and when the temperature of this thermometer reaches 30, 35, 40, 45, 50, 55, 60 ° C, it is removed from the conical tube containing each sample. A 300 μL water sample was quickly collected with a sterilized fin pipette, transferred to a sterilized tube (Assist Tube 72.693.100S, Sarustat Co., Ltd.), and stored on ice until seeding.

5. Method of verifying moderate heating effect on the water supply pipe of a general dental unit Inside the water supply / drainage box (18) of the spit-on device (15) of the water supply pipes of two general dental unit GC company Iom Regalo (manufacture No.00672 and00672) A moderate heating apparatus having the structure shown in FIG. 2 was installed immediately before the internal branch P3 (position indicated by the arrow in FIG. 3) (see FIG. 3). This heating device can heat the temperature in the heating device 40 of the dental unit from 23 ° C. to 65 ° C. in 9 minutes. The casing capacity of the heating device was 180 ml, the heating device voltage was 24 VAC, the power was 52.8 W, the power density was 2.5 W / cm ² , and the maximum temperature (maximum water temperature at the heater outlet) was about 65 ° C.

Before the heating device was operated, flushing (residual water discharge) was not performed, and 25 mL of handpiece water remaining in the handpiece from the previous day was collected in 10 μmL and 15 μmL in a sterile polyethylene tube. Thereafter, the heating device was activated and heated for 10 minutes. Thereafter, operation at the maximum output of the handpiece was started, and 25 mL of water was collected in the same manner after 30 seconds, 1 minute and 2 minutes after the handpiece operation. The temperature was measured using a digital thermometer (CT-05SD, manufactured by Sakai CUSTOM) at each sampling time. The warming device continued to operate until the experiment was completed.

6). Results (1) Examination of culture conditions: Culture results of heterotrophic bacteria and general bacteria in aerobic and anaerobic environments As shown in Fig. 4, as a preliminary experiment before the start of a series of experiments, residues collected from handpieces When heterotrophic bacteria and general bacteria in a water sample were cultured in an aerobic and anaerobic environment, colonies of the heterotrophic bacteria were observed only in the aerobic environment and were not detected in the anaerobic environment. In addition, general bacteria were not detected under either condition. Therefore, in the subsequent experiments, the number of heterotrophic bacteria detected in the aerobic culture was the subject of the study.

(2) Changes in the number of heterotrophic bacteria in general dental unit water due to residual water discharge As shown in Fig. 5, the number of heterotrophic bacteria in handpiece water and gargle water after residual water discharge is compared with that before discharge However, it decreased significantly by about 94% for handpiece water and 98% for gargle water. (P <0.01, paired t-test). In addition, the number of bacteria after discharge of residual water was less than the target value of 2000 CFU / mL in the water containing ginger, but the number of bacteria close to 5 times the target value was detected even after discharge of residual water in handpiece water.

(3) Change in free residual chlorine concentration in general dental unit water due to residual water discharge As shown in Fig. 6, the free residual chlorine concentration in gargle water is the standard value (0.1 mg / Although it was lower than L), it was 0.2 mg / L or more after residual water discharge, significantly exceeding the reference value (P <0.01, paired t-test). On the other hand, the free residual chlorine concentration of handpiece water was about 0.5 mg / L regardless of whether residual water was discharged or not, and did not exceed the standard value.

(4) Number of heterotrophic bacteria in each part of the water supply piping of the dental unit As shown in Fig. 7, water samples were collected from each point in the unit and the numbers of heterotrophic bacteria were compared. In the sample immediately after entering the unit pipe from the water tap (P2), almost no heterotrophic bacteria were detected, whereas the internal branch (P3), the water nozzle (P4) of the Spitton device, and the assistant In the sample collected from the pipe in the table (P5), although it was within the target value of 2000 CFU / mL, the number of detections gradually increased. Furthermore, in the operator's table (P6), the number of detections is around 2000 CFU / mL, and in the sample (P7) from the tip of the handpiece connected by a thinner pipe, the number of detections increases to 150000 CFU / mL at a stretch. Increased. These results show that the number of heterotrophic bacteria tends to increase according to the distance from the main plug. In the unit piping far from the main plug, heterotrophic bacteria contained in water stagnate, and supply of bacteria such as biofilm. This suggests the possibility of forming a source.

(5) Free Residual Chlorine Concentration in Each Portion of Dental Unit Water Supply Piping As shown in Fig. 8, the free residual chlorine concentration immediately after entering the unit piping from the water tap (P1) and water tap (P2) is 0.3 mg / It was over L and greatly exceeded the standard value (0.1 mg / L) of the Water Supply Law. Although the free residual chlorine concentration decreased as it proceeded to the general dental unit, it was still above the reference value in the internal branch (P3) and in the assistant table (P5). However, the water supply nozzle (P4) of the Spitton device, the inside of the operator table (P6), and the sample (P7) from the tip of the handpiece were below the reference value. The farther away from the tap, the lower the residual chlorine concentration tended to be lower.

(6) Number of heterotrophic bacteria in the handpiece water of the dental unit with the drug cleaning function As shown in Fig. 9, the water sample collected from the dental unit handpiece with the drug cleaning function is used as a reference example before discharging residual water. However, the number of heterotrophic bacteria was very small and the target value was cleared. The number further decreased after discharge of residual water. It was suggested that the heterotrophic bacteria in the flow path were sterilized by hydrogen peroxide water circulating in the flow path.

(7) Free residual chlorine concentration in handpiece water of dental unit with drug cleaning function As shown in Fig. 10, as a reference example, in a water sample collected from a dental unit handpiece with drug cleaning function before discharging residual water The free residual chlorine concentration of was less than the standard value of the water supply law. Due to residual water discharge, free residual chlorine concentration tended to increase, but it did not always exceed the standard value. As described above, there was a concern that the concentration of free residual chlorine does not necessarily comply with the Water Supply Law, and that the pipes were continuously corroded by hydrogen peroxide.

(8) Effects of heating on heterotrophic bacteria (in vitro)
The effect on heterotrophic bacteria in the sample when each water sample collected from the handpiece was heated to each temperature in vitro was examined.

As shown in Fig. 11, in the samples collected from the three general dental units targeted this time, the number of heterotrophic bacteria detected was almost flat from room temperature to 45 degrees, but it was more than 50 degrees At 55 ° C or higher, the detected amount was less than the target value of 2000 CFU / mL. It has been shown that moderate heating around 50-60 ° C can significantly reduce the number of heterotrophic bacteria in handpiece water.

(9) Handpieces by moderate heating of water supply pipes for general dental units Hands sterilizing effect on heterotrophic bacteria in water Hands when heated up to 65 ° C by the heating device in the water supply pipe of the unit The time course of temperature and heterotrophic bacteria count in the piece water sample was investigated.

As shown in FIG. 12, the temperature of the water sample collected from the tip of the handpiece after moderate heating was about 33 ° C. at the maximum. This was thought to be because the pipe in the unit from the heating device to the tip of the handpiece had a distance and was cooled in the flow path.

The number of heterotrophic bacteria is greatly reduced in the sample collected 30 seconds after continuing to draw water from the tip of the handpiece, compared with the sample before heating, and the two units clear the target value of 2000 CFU / mL The result was obtained. Thereafter, the decreased state was maintained until 1 minute and 2 minutes later.

It was shown that the heterotrophic bacteria in the unit were sterilized by this heating device and the effect was maintained during drainage.

(10) Effect of moderate heating on water supply piping of general dental unit on handpiece discharge water temperature and free residual chlorine concentration As shown in Figure 13, the temperature of handpiece water of general dental unit is around The residual water at room temperature was about 20 ° C and increased as the residual water was discharged after heating, but it reached a peak at around 30 ° C.

In some cases, the residual chlorine concentration in the water remaining in the handpiece was below the water supply standard (0.1 mg / L) before heating, but the residual chlorine concentration in the water remaining in the handpiece increased significantly after moderate heating. In Unit 1, it was 0.3 mg / L or more, greatly exceeding the standard value of the Water Supply Law. During residual water discharge for 2 minutes, the free residual chlorine concentration never fell below the standard value of the Waterworks Law, and all units were always above 0.2 mg / L.

Based on the above results, in terms of both the number of heterotrophic bacteria and free residual chlorine concentration, sterilization using hydrogen peroxide in a dental unit with a drug cleaning function and the method following the guidelines in the existing hospital infection countermeasure practice manual According to the standards in accordance with the Water Supply Law, water quality management was shown to be difficult. On the other hand, in this embodiment, by attaching a moderate heating device to the branch of the water supply pipe inside the dental unit, the quality of the handpiece water of the dental unit is high in safety and reliability, and the heterotrophic nutrition. It was shown that it can be managed at a level that complies with the Water Supply Law, both in terms of bacterial count and free residual chlorine concentration.

40 ... Warming device, 60 ... Water supply piping.

Claims (7)

Water supply piping,
A heating device attached to the water supply pipe for sterilizing water in the water supply pipe;
The heating apparatus is characterized in that the number of heterotrophic bacteria in water in the water supply pipe downstream from the heating apparatus is 2000 CFU / mL or less. The said heating apparatus is provided with the casing which can accommodate the water in the said water supply piping, and the heater provided in the said casing, The water in the said casing is heated to 50 degreeC or more, The said heating apparatus is characterized by the above-mentioned. The device described in 1. The apparatus according to claim 1, wherein the concentration of free residual chlorine in the water supply pipe downstream from the heating device is 0.1 mg / L or more. The apparatus is a dental unit including an assistant unit and a doctor unit, and the water supply pipe is branched into a water supply pipe leading to the assistant unit and a water supply pipe leading to the doctor unit. The apparatus according to any one of claims 1 to 3, wherein the apparatus is provided at the branching section or upstream thereof. The said doctor unit is equipped with the instrument which is fluidly connected with the said water supply piping, The heterotrophic bacteria count of the water discharged | emitted from the said instrument shall be 2000 CFU / mL or less. apparatus. 6. The apparatus according to claim 5, wherein the temperature of water discharged from the instrument after 2 minutes of heating at 60 to 70 ° C. for 10 minutes by the heating apparatus is 15 to 35 ° C. A method for sterilizing water in a water supply pipe of an apparatus, wherein the water supply pipe is attached to the water supply pipe and is used for heating and sterilizing water in the water supply pipe. A sterilization method characterized in that the number of heterotrophic bacteria in the water is 2000 CFU / mL or less.

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