Field of the Invention

The present invention relates to a device and a method for demonstrating efficacy of oral care implements, especially toothbrushes.

Background of the Invention

Accumulation of plaque has a close link with caries and periodontal diseases. Therefore, it is necessary to mechanically remove plaque.

There are known ways of establishing and demonstrating efficacy of a toothbrush, such as, clinical trials, laboratory tests, and consumer-based trials. WIRA® machines are designed to support mechanical cleaning and gum-abrasion studies. However, the bulky machines are difficult for scale-up and portability. Microbiological protocols cannot be performed on this machine due to fixed design parameters.

US2015262504 A1 (P&G) discloses a toothbrush-demonstration device and system. It has a main body and plurality of toothbrush holders, each of the toothbrush holders being structured and configured to accept and removably secure a single toothbrush in a fixed position. The toothbrushes can be securely mounted substantially parallel to one another for simultaneous movement with the device, relative to a test surface. The system includes the device, two toothbrushes being compared, and a test surface. The device addresses the need for a simple and inexpensive tool to compare one or several toothbrushes with respect to their plague-removal efficacy.

In an in-vitro study authored by Joshi CP et.al, the authors have compared cemental abrasion by soft v/s medium hard toothbrushes, to understand cementum surface wear caused by various manual toothbrushes at different pressures. The study is published in J Indian Soc Periodontology, 2017;21 :10-5 (DOI 10.4103/jisp.jisp_118_17). The device is a customized toothbrushing apparatus. The toothpaste and brushing cycles are kept constant. An analog dial is incorporated to determine and set the force to be exerted during toothbrushing procedure. Their protocol refers to use of human enamel as a test surface.

WO 00/73496 A1 (Optiva, 2000) discloses a plaque removal test method which involves the steps of (i) treating a test surface with saliva (ii) binding cells to the saliva treated test surface to form a biofilm on the test surface (iii) removing cells that are not bound to the biofilm test surface (iv) mounting the biofilm test surface in a tooth prosthesis to form a biofilm tooth prosthesis (v) placing the biofilm tooth prosthesis into a typodont (vi) treating the biofilm tooth prosthesis with an oral care product; and, (vii) quantitatively determining the number of cells dislodged from the biofilm tooth prosthesis.

Usually, the efficacy of a toothbrush is assessed by way of clinical tests which are lengthy and expensive. Therefore, there is a need for a simple device for microbiological assessment linked with plague-removal efficacy of toothbrushes; preferably which permits comparative evaluation of two or more brushes. A further object of the invention is to get results that are at least as reliable as those obtained via clinical tests. An object of the present invention is to develop a device which can be used to quantify plaque-removal using biological parameters.

The present invention is directed to a device for demonstrating efficacy of toothbrushing, especially microbiological efficacy and a method for doing the microbiological assessment.

Summary of the Invention

In accordance with a first aspect, disclosed is a device for demonstrating efficacy of a toothbrush, comprising a body, said body comprising: i) at least one holder to secure the handle of the toothbrush in a fixed position relative to a test surface; ii) a test surface; iii) a means for moving said toothbrush relative to said test surface under variable speed or force; and, iv) a display unit for displaying the speed or force, wherein said test surface is HAP disc comprising a biofilm of a bacterium found in human oral cavity.

In accordance with a second aspect, disclosed is an in-vitro method of testing antibacterial efficacy of a toothbrush, comprising the steps of:

(i) growing a biofilm of a bacterium found in human oral cavity on a HAP disc;

(ii) using said HAP disc as a test surface in a machine as claimed in claim 1 ;

(iii) cleaning said test surface with the toothbrush using water;

(iv) extracting the bacteria from so treated test surface and plating,

(v) incubating said extracted bacteria under aerobic and under anaerobic conditions, separately; (vi) calculating the log-reduction in bacterial count as compared to said HAP disc comprising the biofilm thereon.

The present invention provide a device for demonstrating efficacy of toothbrushing by applying microbial assessment. The device of the present invention tests the performance of the toothbrush which simulates real tooth brushing conditions and provides a device which is easy to use, portable, easy to disinfect after use.

Brief Description of Figures

Fig.1 is an isometric view of an embodiment of a device in accordance with the invention.

Detailed Description of Figures

The device (1) is generally rectangular in shape and has a body (2). On the body (2) there is a pair of spools, spool-1 (3) and a spool-2 (4). The two spools together hold an elastic band (5). The body (2) further comprises a holder (6) to secure the handle of the toothbrush (7) in a fixed position relative to a test surface (8), which is placed on a bed (9) that serves to measure the force. The test surface (8) is an HAP disc having a biofilm of bacteria found in human oral cavity. Bristles (10) of the toothbrush (7) are placed in an abutting position with respect to the test surface (8).

The pair of spools, spool-1 (3) and spool-2 (4) and the elastic band (5) together constitute a means for moving the toothbrush (7) relative to the test surface (8) under variable speed or force. The dial (11) and mode changer (12) are provided to vary the speed or force and to toggle between speed mode and force mode of operations. Readings are displayed on the digital display with PCB unit (13). The display could alternatively be analog.

There is reset button (14) to reset the device and a switch (15) for on-off operation. The power cable (16) can be connected to power inlet.

Features not visible in this view and which are present inside the device there is DC motor (12 V with up to 6000 rpm), Voltage convertor 24V to 12V, membrane switch board, heat sink with MOSFET for voltage management and current distributor.

All the internal parts and their functions are well known to persons skilled in the art.

In use, the way or to operate the device comprises a series of steps, the more important ones are summarised below. 1) Plug-in for power to 5A socket, A/c point

2) Attach the brush to the holder.

3) Before the brush touches the tooth bed, reset the force reading.

4) Use the elastic band and adjust the force (on brush reading to the desired value)

5) The spools are helpful to calibrate the desired force

6) Turn switch ‘ON ¹ position to start the brush movement.

Detailed Description of the Invention

As used herein the term “comprising” encompasses the terms “consisting essentially of’ and “consisting of”. Where the term “comprising” is used, the listed steps or options need not be exhaustive. Unless otherwise specified, numerical ranges expressed in the format "from x to y" are understood to include x and y. In specifying any range of values or amounts, any particular upper value or amount can be associated with any particular lower value or amount. Except in the examples and comparative experiments, or where otherwise explicitly indicated, all numbers are to be understood as modified by the word “about”. All percentages and ratios contained herein are calculated by weight unless otherwise indicated. As used herein, the indefinite article “a” or “an” and its corresponding definite article “the” means at least one, or one or more, unless specified otherwise. The various features of the present invention referred to in individual sections above apply, as appropriate, to other sections mutatis mutandis. Consequently, features specified in one section may be combined with features specified in other sections as appropriate. Any section headings are added for convenience only and are not intended to limit the disclosure in any way. The invention is not limited to the embodiments illustrated in the drawings. Accordingly, features mentioned in the claims are followed by reference numerals, such numerals are included solely for the purpose of enhancing the intelligibility of the claims and are in no way limiting to the scope of the claims. The examples are intended to illustrate the invention and are not intended to limit the invention to those examples per se.

The invention relates to a device for demonstrating efficacy of a toothbrush, comprising a body, said body comprising: i) at least one holder to secure the handle of the toothbrush in a fixed position relative to a test surface; ii) a test surface; iii) a means for moving said toothbrush relative to said test surface under variable speed or force; and, iv) a display unit for displaying the speed or force, wherein said test surface is HAP disc comprising a biofilm of a bacterium found in human oral cavity.

The device

The device of the invention is useful for demonstrating efficacy of a toothbrush. The term efficacy in this context means antibacterial efficacy. The invention relates to a device for demonstrating efficacy of a toothbrush using microbial assessment to demonstrate antibacterial efficacy.

The device comprises a body. The body is preferably composed of a metal or plastic or of a composite material that is suitable for such purposes. The body should be sturdy and durable and should be capable of holding and supporting the electrical and mechanical parts of the device. The body is preferably light weight and portable which enables the device to be easily moved from location to another. This is an advantage of the device of the present invention and its simple configuration enables it to be easily moved around.

Preferably the body is rectangular in shape. Further preferably the length is 12 cm to 25 cm. It is preferred that the width is 8 cm to 20 cm. It is preferred that the height of the body is 10 cm to 20 cm.

The body comprises a holder to secure handle of a toothbrush in a fixed position relative to a test surface. The holder is anything that can hold the handle. It is preferably a mechanical clamping mechanism.

The device includes a test surface. The test surface is HAP disc comprising a biofilm of bacteria found in human oral cavity. The HAP disc is a surrogate for tooth bed. Preferably the test surface may be provided with artificial plaque or stains to simulate real-life conditions of stained teeth.

It is preferred that the HAP disc is a pellicle coated HAP disc comprising biofilm of a bacterium that grows under anaerobic conditions to form biofilm.

Alternatively, it is preferred that the HAP disc is a pellicle coated HAP disc comprising biofilm of a bacterium that grows under aerobic conditions to form biofilm.

Further alternatively, it is preferred that the HAP disc is a pellicle coated HAP disc comprising biofilm comprising at least one bacterium that grows under aerobic conditions to form biofilm and at least one bacterium that grows under anaerobic conditions to form biofilm. It is preferred that the bacterium is from at least one of the genus Streptococcus spp, Gemella spp, Abiotrophia spp, Granulicatella spp, Actinomyces spp, Simonsiella spp, Prevotella spp, Veillonella spp Campylobacter spp and Rothia spp.

Non-limiting specific examples of bacteria of the aforesaid genus include:

• S.mitis, S.parasanguinis, S.intermedius, S.gordonii and S. cristatus and S. salivarius

• G.morbilorum and G.haemolysans

• Abiotrophia defectiva

• Granulicatella elagans, Granulicatella adiacens,

• Rothia denocariosa

• Actinomyces odontolyticus, Actinomyces naeslundii

• Prevotella nigrescens, Prevotella melanogenica and Prevotella oris

• Campylobacter gracilis, Campylobacter curvus, Campylobacter showae, and Campylobacter consicus

• Veillonella parvula and Veillonella dispar

For further details of bacteria that are found in the oral cavity of humans, reference may be made to Aas et.al. , in JOURNAL OF CLINICAL MICROBIOLOGY, Nov. 2005, p. 5721-5732.

The body comprises means for moving bristles of the toothbrush under variable speed or variable force relative to the test surface. Preferably the means comprises spool and an elastic band, where the band holds the brush-head such that the bristles abut the test surface. The spool-band configuration could also be replaced with any other kind of means such as a mechanical arm or an electrically controlled arm. Preferably when the means is a spool-band configuration, it is easily readjusted to provide the desired speed or variable force to simulate the force applied during actual brushing. More preferably the device according to the present invention having a means which is more preferably a spool-band configuration in combination with the display unit provides for better control and closely simulates the actual brushing. The device preferably comprises a motor that drives the moving parts. It is preferred that the motor is a DC motor that works under 12 V and can work upto 6000 rpm. Preferably the means for moving bristles of the toothbrush is detachably attached to the body. When the means is detachable this provides for easy disinfection of the device parts which is highly desirable in the device according to the present invention which measures the efficacy of the toothbrush using microbial assessment. The bristles are moved under variable speed or variable force relative to said test surface. Such variability is necessary to create and simulate conditions of natural brushing by a person.

Where the force is variable, it preferably is from 1.2 to 1.8 N. Where the speed is variable it preferably is from 60 to 80 rpm. It is preferred that the body comprises a switch for toggling between the speed and force.

It is preferred that the device is supplied with electrical power. Alternatively, it is battery operated. Preferably the applied voltage is about 24 V and the device comprises a voltage convertor that can reduce the voltage from 24V to 12V. The body comprises a display unit for displaying at least the speed or force. The display unit is preferably of the digital type. Alternatively, it is analog. The display unit in the device of the present invention displays at least the speed or force. The display unit quantifies and display the speed at which the brush is moving or the pressure the brush is applying on the test surface which enables to set or adjust the means provided on the body of the device to a desired predetermined force of 1.2 to 1 ,8N and preferably a predetermined speed of 60 to 80 rpm. Preferably the testing time is 2 minutes.

Then device preferably comprises a membrane switch board. The device preferably comprises a heat sink with MOSFET for voltage management. It is further preferred that the device comprises a current distributor.

The device of the invention is useful for testing antimicrobial efficacy of a toothbrush. Preferably the brush is manual. Alternatively, it is electrical, or battery operated.

It is preferred that device comprises a weight-adjusting means for adjusting an overall weight applied to the handle. This feature is preferred because it can help to simulate the conditions prevalent at the time of use of the brush by a variety of individuals such as children, able-bodied persons and old or infirm individuals.

The device according to the present invention preferably includes body with detachable parts. Preferably the holder to secure handle of the toothbrush in a fixed position relative to a test surface is detachably attached to the body. Preferably the test surface is detachably attached to the body. Preferably the means for moving bristles of the toothbrush under variable speed or variable force relative to said test surface is detachably attached to the body. The detachable parts of the device are easily removable and disinfected after the study. The method

The method is an in-vitro method of testing antibacterial efficacy of a toothbrush. The method comprises the steps of:

(i) growing a biofilm of a bacterium found in human oral cavity on a HAP disc;

(ii) using said HAP disc as test surface in a device as claimed in claim 1 ;

(iii) cleaning said test surface with a toothbrush for about 120 seconds under a preset speed or force using water;

(iv) extracting and plating the bacterium from the treated test surface,

(v) incubating said extracted bacteria separately under aerobic and anaerobic condition;

(vi) calculating log-reduction in bacterial count under each said condition as compared to an untreated HAP disc.

It is preferred that bacterium found in human oral cavity means the bacteria found in or on at least one of teeth, tongue, cheek and gums.

To form the biofilm, in a first step the disc is placed in a well containing 1 ml clarified saliva and is kept for pellicle to form in an incubator at 37°C for 30 minutes. In the second step, the disc is given a one-dip wash in 4ml 1x PBS in a 12 well-plate. In step 3 the disc is transferred to a well containing pooled bacteria, 5% sucrose and TY broth (160 pl pooled bacteria + 1840 pl TY broth with 5% sucrose). In the next step the plates are incubated for about 20 hours at 37°C under anaerobic conditions to form good biofilm. In the last step of formation of the biofilm, the HAP discs are rinse by dipping thrice (triple dip wash) in 5 ml sterile water in a well plate to remove nonadherent bacteria.

In step (iii) of the claimed method, the test surface (comprising biofilm) is cleaned with a toothbrush for about 120 seconds under a preset speed or force using water. Six discs with preformed biofilm thereon are taken. Three discs are left untreated for baseline count. Three other discs are used in the method as described in steps (iii) to (v) above.

Bacteria are extracted from the treated discs (each disc separately) and then plated with one set of discs plated under aerobic conditions while the other set meant for anaerobic conditions.

The method of the invention is an ex-vivo reproducible method applied to differentiate the effects of water vs. toothbrush alone or water v/s a standard toothpaste. Bacterial populations are assessed on total aerobic and total anaerobic count. The invention will now be described in details with reference to the following non-limiting examples.

Example 1

Bacterial samples representing the whole mouth (teeth, gum, tongue and cheek) were collected using a swab from subjects/volunteers who were in good general and oral health. The site-specific samples were homogenised, washed, and suspended in phosphate buffered saline (PBS) and the optical density (OD) was adjusted to 1. Sterile Hydroxyapatite (HAP) disc were placed in a 12-well plate containing 1 ml clarified saliva and incubated for pellicle formation for 30 minutes at 37°C.

Pellicle coated hydroxyapatite (HAP) discs were then transferred to the well containing pooled bacteria and 70% Brain Heart Infusion Broth (supplemented with 5 % Sucrose + 30% clarified Saliva) and incubated for about 20 hours at 37°C under anaerobic conditions to form biofilm.

To perform untreated (baseline) plate counts, HAP discs were rinsed by dipping thrice in 5 ml sterile distilled water in a well-plate to remove non-adherent bacteria.

The other set of HAP discs were then subjected to the toothbrush machine for 2 minutes contact time and 1.5 N force with moderate speed of 70 rpm (140 to 150 brushing cycles). This was considered as the “treated” group.

Later, the biofilm was extracted from both “untreated” & “treated” group, serially diluted, and plated further on BHI agar (Brain heart infusion agar) for enumeration of total surviving bacteria count (total viable count, TVC) - one set for aerobic & another set for anaerobic.

The incubation conditions were as follows:

Anaerobic: (80% N ₂ , 10% H ₂ and 10% CO ₂ ) 37°C (±1°C) for 3 days.

Aerobic: CO ₂ incubator (37°C (±1°C) and 15% CO ₂ (±1%) for 3 days.

Viable log 10 values were then calculated and compared to get a log difference value of treated versus untreated group.

As far as the device is concerned, the force was kept in the range of 1.5 ± 0.3 N. The speed was set at 70 RPM. The device was powered with 24 V. The brushing time was manually controlled at 2 minutes. The brushing cycle was set at 140 ± 10. The data is presented in Table 1.

Table 1

The data indicates significant difference between untreated (baseline biofilm count) and toothbrush plus water treatment, under both aerobic and anaerobic conditions. There was 99% reduction (2 log) in baseline biofilm count with toothbrush plus water treatment under the aerobic and the anaerobic conditions.

With reference to the observations recorded in Table 1, it is possible to claim that the tested toothbrush cleans 99% of bacteria found in the oral cavity, particularly bacteria found in or on at least one of teeth, tongue, cheek and gum. The novel device of the invention in this ex-vivo biofilm model proves that the toothbrush performs statistically superior to the untreated test option and gives a 2-log reduction (99% bacteria reduction) as against untreated test option.