Equipment for Donkey Dentistry

EQUIPMENT FOR DIAGNOSIS

The general equipment required for an oral examination is presented below but does not take into account items required for personal protective equipment or biosecurity.

• appropriate method for secure elevation of the head i.e. head stand/hanging halter

• full mouth speculum with the correct plates for the patient and of correct size (mini, standard etc)

• buckets

• clean water

• dosing syringe/irrigator (irrigator with a 90° nozzle is very useful for removing food from the interproximal space)

• bright headlight/light source

• mirror/endoscope

• occlusal probe(s)

• periodontal probe(s)

• periodontal forceps

Specula

One of the most important pieces of equipment is the speculum.

It is used to facilitate visualisation and manual evaluation of the oral cavity. There are several types of specula available, but a full mouth speculum is recommended.

The McPherson/Hausmann's specula are very popular as they offer access to the whole mouth. They work on a ratchet and spring (leaf or coil) system, and may be safely used in conjunction with a headstand/hanging halter.

Interchangeable bite plates are available for the McPherson/Hausmann's specula:

• incisor plates that fit the contours of the incisors

• bar plates that fit along the bars of the mouth (for geriatric patients with loose/expired incisors, or when treating incisor conditions, including brachy/prognathia)

• extended width plates that offer increased access during assessment and treatment

• ground out plates that offer additional surface area for examining/treating brachygnathic/prognathic patients.

These specula are ideal for use in most standard size donkeys. Some suppliers offer a pony or mini sized version which would be suitable for miniature donkeys.

Millennium-type specula are similar to McPherson/Hausmann's-type speculae, but they offer a greater number of smaller ratchets for easier opening.

The standard size would not be the speculum of choice in the standard or mini donkey or in smaller mules because the length and arch of the lateral frame usually presses on the ocular area when fitted. There are pony sized versions of millennium specula available and many contemporary specula that do not have any ratchets at all. The smaller sized specula in these ranges may be useful in standard and mini donkeys or mules.

It is common practice to fit this speculum upside down as the ratchet release lies ventrally along the frame. The risk of using conventional orientation, is that the specula may be inadvertently let down when stabilising the head of a sedated patient on a headstand.

An essential addition to your speculum would be biothane straps, which make the instrument easier to clean and disinfect, and add longevity to the instrument.

Headstand/hanging halter

These support the head weight of the sedated patient. Note:

• there must be a safe means of dealing with failure of devices, the headstand can become a heavy obstacle if the patient objects to handling/procedures and the hanging halter can provide opportunity for entanglement or prevent a safe means of escape. (For example, in the case of an animal’s uncontrolled rearing, the halter can prevent safe landing.)

• a head suspension collar is especially useful when treating donkeys in horse-sized stocks, because usually the front padding is too thick to be able to place the headstand under the donkey’s head. The hanging halter method for elevating the head is usually achievable in resource limited environments.

• most of the standard headstands available are too high for use with standard/mini donkeys/mules and require modification by means of a reduction in the length of the main upright section, or the purchase of a pony sized column.

• where a traditional head stand is not available, an alternative means of providing stable cranial elevation may be, a bale of shavings/hay/ straw, a small water barrel or a chair/stool etc.

Light source

A bright head light is the preferable light source. Speclights that fit onto normal bite plates of full mouth specula can also be used to illuminate the oral cavity, facilitating a thorough examination and treatment, although they may impede instrumentation. They are often useful for showing conditions to owners/handlers.

Mirror or oroscope

A mirror or oroscope allows the professional to visualise the otherwise unseen aspects of the oral cavity.

A long handled mirror should be considered the basic essential for routine examination. Professionals are advised to select an appropriate size, for example those with a mirror diameter of 30-35mm are readily accepted by the majority of equids. It is common to see professionals struggling to use mirrors of excessive diameter which are uncomfortable for the patient.

Irrigation devices

Oral irrigation devices include:

• dose syringes

• battery or manual pressure sprayers with a modified hand piece, for washing out the mouth pre, post and during treatment and for flushing sockets, diastema, etc. It is preferable to use lower pressures for the irrigation of diastema; high pressures may move static ingesta/ foreign bodies deep into the lesions, and may cause significant trauma to friable tissues.

• pressure spray attachments for standard hoses, for washing out the mouth pre, post and during treatment.

EQUIPMENT FOR TREATMENT

The equipment listed below is the main instrumentation required for routine dentistry, including the extraction of wolf teeth, incisors and cheek teeth in field settings (i.e. non-surgical, non-clinic setting). This section does not include instrumentation for complex cases or advanced/specialist procedures.

Manual floats

When treating standard donkeys, it is possible to use some of the same size floats commonly used for horses and ponies, this will be dependent on personal preference. However, the low-profile ‘pony’ floats that are available are of particular use and are recommended if regularly treating smaller equids. The Donkey Sanctuary include one straight low-profile pony float, one upper 11 low-profile pony float, and one low profile pony premolar float in their standard dentistry kit (as a complement to motorised instruments).

Rostral profiling may be uncomfortable for the donkey when using the premolar roller, especially in relation to the lower 6s. It may be best practice to use the flexi disc or apple core initially, and then finish, if required, using a small diamond grit S float.

It is common to assume that injury may be caused from inexperienced use of motorised instrumentation (thermal damage, soft tissue burns, removal of too much crown, and/or injury to the pulp), but it must be stressed that manual floats can also be a source of considerable oral trauma.

Manual instruments for crown reduction

Cutters, including captive bolt percussion instruments, are now obsolete. The likelihood of iatrogenic damage is extremely high compared with the use of motorised instruments.

They may, however, still be in use in resource limited communities where there may be little or no alternative. In such circumstances, controlled manual fracture instruments may offer immediate relief from gross overgrowths which are limiting food intake and threatening the health and welfare of the patient, they are however, not without extremely significant risk.

Motorised instrumentation

Motorised instruments have become a valuable asset to equine dentistry, offering efficiency and precision, making them ideal for use in routine and advanced cases.

There are three main types of motorised dental equipment:

• Reciprocating instruments
  
  These have a rostro-caudal stroke. More contemporary developments have enabled a smaller engine stroke and low-profile attachments, making the mini Makita-style instrument ideally suited to ponies and donkeys.
  
  It is important to note that the reciprocating nature of the instrument presents a danger to the caudal anatomy of the mandibular arcades (the vertical ramus). The closed-angle attachment is, however, useful for the maxillary 11s when used with skill and care.
  
  This instrument is of use for treating patients with trismus (limited opening of the mouth) but is generally surpassed in terms of ease of use, efficiency and quiet operation by rotary and/or axial instruments.
   

• Flexible shaft instruments
  
  These are extremely popular as they are easy to use and manoeuvrable enough to reach the buccal/lingual areas in addition to the occlusal surface.
  
  The unit usually comprises a small motor (typically worn around the operator’s waist), flexible drive shaft and interchangeable hand pieces. It may be operated by a simple on-off switch, variable speed foot pedal, or even a variable speed trigger.
  
  Attachable hand pieces are usually axial burr type and rotary disc/burr (including lateral burrs) and may be curved or straight. A selection of different lengths of extension handle are available, although many of the latest hand pieces come as one long fixed length.
   

• Drill instruments
  
  These are typically modified hand drills with a long, fixed shaft. The head may or may not be fixed and is typically a rotary disc style with the ability to change the disc to a lateral burr (applecore, diastema burr and similar). Rotary disks are very efficient at removing dental materials, but may create dust. They are useful for both occlusal table work and buccal/ lingual points.

The Donkey Sanctuary uses a flexible shaft instrument with rotary/axial burrs, curved rotary disk and apple core/lateral burr hand pieces.

The vast majority of donkeys readily accept the use of motorised instruments without the use of sedation.

Thermogenesis can be combatted by efficient operation, cleanliness and serviceability of instruments and of course the availability of water to cool the burrs and oral cavity. Water cooling may be as basic as regularly flushing the mouth out and dipping/cleaning the instruments in clean water. More advanced units allow for water to be piped directly to the burr either using a drip bag or a reservoir. To avoid the thermal damage that can result from using motorised equipment, practitioners must be vigilant and move around the mouth as much as possible, spending no more than 10 seconds at a time in one place and keeping reductions within clinically justified normal limits.

Safety must always be considered when using motorised equipment in a wet environment:

• Consider using a battery powered motor.

• When using mains powered instruments, plug in an electrical tester to assess if the supply is earthed (you will be surprised how many yards are ‘live’). Also, test your own extension leads, regardless of age/usage.

• A residual current device (RCD) should always be fitted at the plug socket.

• Consider using a transformer (from 240v to 110v).

• Some power equipment has the option to use a clutch device to cut the drive when the burr/disk is chewed or soft tissue becomes entangled. This may be a simple replaceable shear pin, or a more complex unit placed between the motor and drive shaft or drive shaft and hand piece, or maybe built directly into the engine control unit of modern battery devices. This will also reduce wear on the drive shafts.

• A vacuum attachment may be a consideration if regularly using power equipment. However, they are quite noisy, require additional set-up time, and are only available on certain instruments.

• Masks would be considered obligatory and goggles are strongly advised.

Diamond grit burrs/disks, if well maintained/cleaned, are particularly efficient, remain sharper for longer, and create a smear layer on the tooth.

Table showing a comparison of the use of manual or motorised equipment.

Forceps

Different sizes of forceps have different uses:

• Short-handled incisor/wolf tooth forceps are used for extracting rostral teeth and removing calculus from canines and incisors.

• Long-handled forceps are used for deciduous cap and molar extraction. Hewson-style, with the smaller head, or lightweight maxillary Reynolds-type forceps are ideal for donkeys.

• Horse molar forceps are usually too big for use in standard and mini donkeys/mules. Narrow headed maxillary Reynolds-type forceps are useful, as are the Hewson-style and some of the modern Pegasos forceps.

Elevators

Note:

• When elevating teeth for extraction, the elevator should be of relatively thin material at the head to minimise tooth breakage.

• A selection of lengths and angles is useful for elevating incisors, canines and wolf teeth, or fragments left from incomplete wear and/or fracture.

• The elevator must be regularly sharpened.

• Cheek tooth elevators are now widely available.

• Burgess style wolf tooth elevators remove a cylindrical core of tissue and have a higher incidence of crown fracture during extractions. They are not the preferred style of elevator. Wolf teeth come in many shapes and sizes and typically have tapered roots, making the Burgess kit an inappropriate instrument in most instances.

Picks/probes

These have many uses:

• They can be used to clear diastema for evaluation, although flushing is preferable to minimise iatrogenic damage. Some measuring probes are too long in the head to allow use in the donkey, consider using a smaller head depth, or trimming it down.

• In the case of thinner headed picks, they can be used as long-handled elevators for cheek tooth extraction.

• They can be useful for occlusal surface and pulp horn/secondary dentine integrity investigation.

CARE OF EQUIPMENT

Instruments work best when they are well maintained, sharp, clean and adequately lubricated.

General care

Elevators

• Instruments with cutting heads, for example wolf tooth/cheek tooth elevators, should have their heads resharpened regularly, preferably using a diamond file or fine burr on a rotary tool.

• The instrument head needs to be thin enough to access the periodontal ligament and sharp enough to cut the attachment without the need for excessive force.

• The cutting head needs to be protected during storage and use to prevent unintentional damage to the elevator and surrounding equipment/personnel.

Manual floats

• Hand floats will eventually require a change of cutting blade, consider sourcing instruments that accept readily available blades such as those secured using screws or those affixed using very high bond tape.

• The frequency of replacement will be determined by the amount of use and how the instruments are stored, as a rough guide:

  • blades used for the majority of cases i.e. 50–80mm flat blades for use on all arcades for routine work are typically replaced/resharpened around every 30–40 cases

  • blades used for floats that are used intermittently or are focussed for use in one or two areas only, may be replaced/resharpened less frequently (i.e. every 40–70 cases)

  • triangular tool tip style blades are more aggressive and last much longer (1.5–2 times) than the flat carbide style, but are consequently more expensive.

• Not only does the use of blunt blades present a risk of iatrogenic damage due to the use of excessive force and less friction to ‘grab’ onto the dental tissues (thereby increasing chances of slipping off the teeth), but also it contributes to significantly increased operator fatigue and treatment duration while reducing overall satisfaction of the procedures.

• To replace your manual float blades, first take note of the direction of the cut of the blade. Then, undo the screw on the reverse of the blade (or at the base of the head if using triangular tool tip style inserts) and remove the blade by sliding it out (or removing the central pin and withdrawing the inserts). When replacing the blade/insert, be sure the orientation is correct for the desired direction of cut. Torque securing screws to the specified figure recommended by the manufacturer.

• For blades attached with very high bond tape, take note of the direction of the cut of the blade and then simply soak the instruments in hot water. After sufficient heating, the blade should peel off using a thin bladed tool to lever it from the float head. To replace, ensure the recipient surface is clean and degreased. If your blade was not supplied with tape attached, degrease the rear of the blade and cut a section of tape to length (it is the author’s preference to use double-sided, closed cell acrylic foam very high bond tape available from most DIY stores). Soak the float head in hot water and dry thoroughly or use a heat gun. Once the float head is warm, remove the backing from the tape and firmly apply the blade in the orientation required. It is beneficial to weigh or clamp the blade in place for several hours or overnight if possible prior to use.

Motorised instruments

• Although acceptable for manual equipment, most motorised instruments should not be left in water for any length of time as this may cause the bearings and non-stainless steel components to rust/ seize prematurely.

• Diamond coated disc heads and burrs generally last around 400–500 cases. There are instances when they have lasted significantly less/more and again usage and maintenance will have an impact on longevity as will build quality.

• Discs/burrs require cleaning during and post use. A bucket of water and a hard bristled brush (some stainless steel wires brushes are effective) will be sufficient to clean the heads frequently during treatment to limit build-up of tooth dust which will reduce the effectiveness of the grinding surface. Frequently dipping the instrument head will ensure it remains somewhat lubricated for use in the mouth and will reduce soft tissue injury in addition to providing some protection against soft tissue burns and pulpar thermogenesis/necrosis.

• It is generally not necessary for the water used for instrument cooling/ cleaning during treatment to be medicated.

• Depending on the manufacturer’s advice, it may be necessary to grease the instrument after each patient, or at the end of the day/other prescribed time/indicator. The manufacturers advice for the specific instrument should be followed, but as a guide lubricating at the end of each day is a sensible precaution (albeit that the bearings are usually sealed to prevent leaching/ingress). Sufficient grease should be added to provide adequate instrument maintenance without encouraging emergence from behind the disc head during use in the mouth. If too much grease has accidentally been added, the hand piece should be run before its use, until the grease stops appearing at the surface; pressure should be applied to the disc using paper towels to ensure no more grease will emerge during use.

• Grease is usually added using a chainsaw type lubrication gun to external points on the hand piece – these are usually on the front or back of the instrument head.

• Applying grease to the internal drive cables of both the hand piece and the long drive shaft prevents rusting from condensation and water ingress but will demand tooling (including liquid thread lock) and prior knowledge of drive shaft disassembly and reassembly.

Use of grease

Grease is essentially mineral or vegetable oil combined with a soap (non- detergent salt of fatty acids), which allows the product to remain on the working surfaces of gears or bearings for example, and allow for their continual lubrication. Not all soaps however, are compatible with each other and sometimes the addition of an incompatible grease to whatever has been used previously will cause separation, leaving the oil to settle at the bottom of the compartment in which it is placed and no longer offering lubrication. One solution is a complete strip down of component parts (potentially unsealing bearings), degreasing thoroughly and re-greasing with your chosen product (if the original product cannot be determined). Alternatively, a continuation of use of the manufacturers preferred grease should ensure adequate lubrication.

The type of grease needs to be appropriate to the use, internally in the drive cables/shaft it would be appropriate to use a lubricant suitable for high speed flexible shafts with the mind-set that too much lubricant can cause flexi-shafts to get very hot during operation. There are no equine dental industry standard guidelines for the scheduling of lubrication, but following other flexible shaft maintenance directions, the shaft may benefit from initial degreasing every other time the cable is lubricated.

Where there is a potential risk of ingestion, it is advised that high quality food grade grease be used. Non-toxic greases and cleaners should always be employed.

Storage

Floats

Solid carbide blades will chip and become blunt if stored inappropriately – it is necessary to protect the blades from knocks and drops while in the bucket ready for use, during cleaning, sterilisation and during transport/storage.

Consider using tubular inserts for buckets, to protect hand floats.

Specula

If knots have been tied in speculum straps to allow placement on smaller equids, it is important they are removed as soon as possible to avoid damaging the biothane. Pay regular attention to the springs (if present) and the securing screws. Often the securing screws may be hex head, which typically round easily, making changing the springs very difficult, using a rotary tool or hacksaw, a slot can be made into the head facilitating removal using a flat head screwdriver.

Motorised kit

The weak points of the long drive shaft appear to be a couple of inches from the end that attaches to the motor and this is likely to be from the cable coiling during storage. It is preferable to remove the cable and store it without coiling or kinking wherever possible. The weak point of the hand piece drive cable is usually just below the point where it attaches to the head, it usually breaks owing to wear and tear related rust and metal fatigue.

Hand pieces should be stored clean, sterilised/disinfected and dry with their heads down to encourage any water that may have leached inward to escape. Most contemporary hand pieces are robustly built, but still demand respectful ownership.

It is useful to have a secure means of storing the motor away from other instruments especially hand pieces as they may damage the motor, including by generating condensation if put away wet.

Troubleshooting for motorised equipment

The following guide has been produced for the most popular style of electro-mechanical equipment for occasions when the unit is no longer removing dental tissue during use:

Has the motor stopped?

Is the instrument head turning when the motor is on?

BIOSECURITY

As with many other procedures, biosecurity is an essential consideration when carrying out dentistry, it helps to minimise the potential spread of infectious diseases both between patients and between premises. One of the main threats is from another equid whether by direct contact or via contaminated personnel and equipment (including vehicles).

While professionals are obliged to take responsibility for their own practice, it is equally important that owners understand their own responsibilities for the protection of equids.

There are four main influences to consider in the prevention of infectious disease:

• Awareness of any relevant diseases in the locality, or in the country (including signs and subsequent actions)

• excellent hygiene

• policies for the introduction of new equids

• vaccination where appropriate

In some countries and industries, not all of the above are immediately practical, for example isolation (both by location and in time) would be very difficult to establish for the introduction of new equids where they are used in brick kilns.

Equipment will be an important vehicle for the indirect spread of infection due to contamination. Dental equipment could easily be contaminated with saliva, mucous and blood as well as the normal fomites expected in other situations.

The primary material used in dental equipment is stainless steel, which when clean, offers good disinfection potential. The addition of biothane speculum straps and rubberised manual float handles also offers opportunity for professionals to reduce their chances of spreading disease.

Professionals need to bear in mind their own personal protective equipment and its ability to harbour spores. As a minimum, a change of outerwear, or a clean down with disinfectant, between yards/locations is essential. Footwear that is appropriate in terms of safety (i.e. steel toecaps), needs to be able to be cleaned and disinfected between yards. A suitable protocol for dental professionals would be to:

• wash hands before and after handling equids, with particular attention to nails

• wear disposable gloves and change them in between each patient

• clean instrumentation between patients using a safe product (e.g. chlorhexidine; hibiscrub or similar)

• clean and disinfect/sterilise instruments between yards (rinsing with non-contaminated water and dried prior to storage)

• take apart instruments at the end of each day and clean thoroughly (using an enzymatic cleaner if required) before sterilising in a safe product.

Professionals should routinely carry biosecurity personal protective equipment, such as disposable, dark coloured overalls. Sealable bags/ containers can be used to hold contaminated clothing and instrumentation. As available resources vary greatly between premises and owners, professionals are best advised to ensure they are self-sufficient in terms of the provision of cleaning and disinfection products, including a supply of clean water. It is important that professionals are seen to be clean and taking sensible biosecurity protocols.

It may be necessary to treat infected animals with dental conditions, or animals in the same group as infected donkeys. Treatment should be scheduled so that these animals are the last to be treated or examined and so that there is enough time before further contact with equids for any risk of spread of disease to be eliminated. The time between treating infected equids and moving to another location/treating other non-infected equids should be sufficient to allow for instruments and outerwear to be thoroughly deep cleaned and sterilised where possible.