By Willem Schaftenaar (DVM) with a big thank you to the dental team of the Colyer Institute in San Diego: Jim Oosterhuis (DVM), Dave Fagan (dentist, and founder of Colyer Institute), Jeff Zuba (DVM, elephant anesthesiologist), Allison Woody ( board certified veterinary dentist), Fred Pike (DVM, board certified veterinary surgeon)
Tusk fracture repair
Tusk fractures are not uncommon in elephants, both in the wild as well as under captive conditions. A tusk fracture can be the result of fights, playing with "toys" (e.g. a tire hanging on a chain), digging in the soil or hitting a wall or other heavy objects (e.g. bulls into musth). Fractured tushes in female Asian elephants usually need no treatment, as the dental pulp does not pass the tusk sulcus. However, fractures in tusks are vulnerable for pulp exposure. If not treated in due time, exposed pulp may will become infected and may die, resulting in the loss of the entire tusk.
Cutting the tusk too short may also result in pulp exposure.
Sulcus infection after tush fracture
If a tush or tusk fractured proximal to the tush sulcus, sharp pieces of the remaining part of the tush or tusk may cause wounds in the sulcus. Treatment consists of removing these sharp edges of the tusk by rasping them off. The sulcus wounds should be treated like a superficial skin wound by daily cleaning and flushing with saline solution and an antiseptic (e.g. Betadine-iodine or Chlorhexidine 1%).
WARNING: if the pulp tissue is exposed, the elephant should be vaccinated against tetanus!
Pulp exposure and tusk growth
Exposure of the pulp tissue always results in a bacterial pulpitis. As long as sufficient healthy pulp tissue is present in the apex of the tusk, the tusk may continue to grow. However, if the pulpitis is not treated properly, the infection will finally affect the entire pulp and the tusk will become necrotic and will need to be extracted.
Treatment of open tusk fractures
There are 2 approaches that are being applied as treatment of a fractured tusk:
A. Conservative treatment
B. Surgically filling the pulp canal
A. Conservative treatment of fractures with minimal pulp exposure: daily cleaning and flushing with saline solution and an antiseptic (e.g. Betadine-iodine or Chlorhexidine 1%). This is not the preferred treatment option as it will often result in a permanent fistula, as shown here on the photo (small black spot). Nevertheless, the pulp canal was closed by newly formed secondary ivory.
Conservative treatment of a tusk fracture with exposed pulp tissue, treated conservatively. The pulp canal closed in 3 months, leaving a very small fistula, which luckily that did not cause any clinical troubles during the following (6+) years.
B. Surgically filling of the pulp canal
The difference with a conservative treatment approach is the active closing of the pulp canal by a dental surgical procedure. This procedure consists of a partial pulpectomy, followed by closure of the pulp canal and will be described below:
Tusk repair procedure
Until the actual repair procedure will take place, any free hanging pulp tissue should be cut off and the exposed pulp tissue should be cleaned and flushed 3-4 times per day with saline solution. End each session by spraying Betadine solution or Chlorhexidine 1% over the pulp tissue. Antibiotics are usually not required as the wound is open and under control by flushing. However, the elephant should be vaccinated against tetanus. NSAIDs are only needed if the elephant shows signs of pain.
The tusk repair procedure should be performed as soon as possible after the tusk fractured.
Fractures that are more or less perpendicular to the tusk length axis have better chances to heal than oblique fractures that extend beyond the sulcus. The best chances to heal properly are fractures with a tusk remnant that allows perpendicular shortening through healthy pulp tissue. In the photo shown here the following structures can be distinguished: exposed pulp tissue, the wall of the tusk remnant and the sulcus mucosa.
If the remaining pulp tissue is hanging outside the tusk remnant immediately after the fracture, it is very likely that the proximal part of the remaining pulp tissue has detached from the inner tusk wall, which will result in pulp necrosis if not treated immediately after the tusk fractured. If sufficient pulp tissue can be removed to reach healthy tissue, the prognosis of complete healing is better than in case the pulp tissue encountered after pulpectomy is still detached from the inner tusk wall.
Pulp tissue that is hanging outside the pulp canal should be cut off as soon as possible.
Preparation
–Check the equipment list
–Prepare the area where the elephant will be treated
Standing sedation or general anesthesia?
Depending on the conditions of the facility, the procedure can be done under:
- Standing sedation, using detomidine and butorphanol (or xylazine and butorphanol if detomidine is not available). Azaperone can be used as premedication. Xylazine alone has also been used in a range country where detomidine was not available. There must be sufficient access to the working area. Best is to chain the animal to a wall on both legs on the contra-lateral side of the fractured tusk. The use of a belly belt around the abdomen is highly recommended for safety reasons in case the elephant goes down.
- General anesthesia is not strictly required, but under certain circumstances it is a good alternative if standing sedation is not an option.
Once the animal is secured either in standing sedation or under general anesthesia, the tusk repair can start:
Step 1: create sterile workfield
1. Scrub the affected tusk thoroughly using Povidone iodine scrub.
2. Cut off the tip of the fractured tusk using a giggli wire. Keep the soft tissue out of reach of the giggli wire!!!
3. If present, remove all abnormal (black) ivory using the Dremel.
4. Clean and brush the area (tusk and face) with soap and Betadine scrub. Flush with Betadine solution and alcohol (70%).
5. Cover the surrounding, disinfected skin with a sterile surgery sheet (secure with duct tape)
6. Put on surgical gloves and suit.
Step 2: filling the pulp canal
7. Cut off 20-50 mm of the pulp tissue (depending on the diameter of the open pulp canal). If any pulp tissue has been pulled out when the tusk fractured, it is assumed that it has been separated from the tusk wall and when it snapped back in, it probably pulled in bacteria. So even if the pulp looks fresh when doing the pulpectomy, i.e., bacteria could be lurking way up the wall of the canal that you can't get to. This is a challenging part of the procedure. The pulp tissue has a rubbery consistency and needs to be cut with very sharp instruments (curved scissors and scalpels). High-speed cutters used in hip replacement procedures in dogs (Acetabular Reamer) have been used.
Depending on the diameter of the pulp canal, a decision needs to be made either to fill the pulp canal at this point, or to bring in a threaded rod to stop the bleeding. If the pulp diameter is less than 5 mm, one can decide to skip the threaded rod method (skip steps 8, 9, 13 and 14).
A threaded rod should be used in any pulp canal diameter larger than 5 mm. In that case, follow the entire procedure as written below.
8. Drill the pulp canal out to a perfectly round hole at the proper size, which corresponds with the diameter at the end of the drilled hole.
9. Tap threads into the wall of the tusk so that you have full threads of the plug in the tusk, PLUS, at least 2-3 cm of tusk wall above the plug.
10. Stop bleeding by compressing the pulp tissue gently with epinephrine-impregnated gauze (for several minutes).
11. Fill in the canal with Calcium Hydroxide or calcium hydroxy apatite with a push rod, which mixes some with the blood, and occasionally stops the bleeding for a short time. Other calcium sources that have been used successfully are: Calcium hydroxy-apatite paste (made at location by mixing powder with chlorhexidine or sterile water) and milled and sterilized Portland Cement.
12. Once the canal is full, clean out the calcium from the threads (usually the blood is oozing thru by then).
13. Screw in an inert plug. Plugs of different materials have been used, ranging from special human-grade, all the way to hardware store drain plugs made of PVC, ABS, polyoxymethylene and even brass. Sizes have ranged from 5-50mm diameter. The blood acts as a lubricant when the plug is screwed in. It also forms a nice clot next to the plug to aid in the formation of the dentin bridge.
14. The plug needs to be recessed at least 10 to 20 mm so tusk repair material can be placed over it.
15. Then flush the small remnant of the pulp canal with Chlorhexidine 1%.
16. Flush again with saline solution.
17. Let dry (if needed, use a hair dryer)
18. ETCHING: rub an etching agent on the dentin wall of the pulp canal (cotton-tip) for max. 15-30 seconds. 3M™ Scotchbond™ Universal Etchant Etching gel is a good choice; phosphoric acid (H3PO4 37,5%) or hypochlorite (NaOCl 3%, bleach) are alternatives.
19. Let dry again; use a hairdryer to reduce drying time.
20. Close the pulp canal with glass-ionomer cement. Fill the canal, but leave 5 mm for the composite.
21. Clean the cut-off side of the tusk or sand it with sandpaper.
22. Apply etching (15-30 sec), rinse again and apply bonding for composite application (e.g. Scotchbond Universal Etchant Etching gel (H3PO4 37,5%) and Scotchbond Universal Adhesive).
23. Cover the cement and surrounding area with a layer of dental composite self-curing or light curing, depending on availability of UV-light source (e.g. Tetric Evo Ceram/MIRIS/Filltek/…).
24. Cover the entire cut-off side of the tusk with epoxy glue for extra protection.
25. The tusk will then gradually wear down and the time the wear reaches the plug, the dentin bridge will have formed. At that point, the plug will usually pop out and if needed the hole can be again filled with your favorite tusk repair material.
Final stage of tusk repair showing 5 different layers
Photo gallery
Right tusk fracture in a 5-yr old Asian elephant bull. No attempts to fill the pulp canal were done, resulting in a bacterial pulpitis. By daily cleaning and flushing the deeper part of the pulp remained healthy, resulting in continuous growth of the tusk for at least 2 years. In the end, the conservative treatment resulted in complete necrosis of the tusk
Tip of the fractured tusk and pulp of the same 5 yr-old Asian elephant bull
Left tusk fracture in the same 5-yr old Asian elephant bull with the same development course as the left tusk (tusk necrosis)
Tusk fracture in a 9-yr old Asian elephant bull that was successfully repaired. See also case report.
Tusk fragments of the same 9 yr-old Asian elephant bull.
Tip of the tusk after it was sawn off using a giggli wire.
During sawing off the tusk tip, the sulcus was lifted using an elephant hook in order to prevent the giggli wire cutting into the skin.
When the tusk tip was removed, a large crack filled with dirt became visible.
A 'Dremel' hand tool with an extension cable was used to clean out the dirt from the crack. The diameter of the pulp canal was approximately 5 mm. Hence, no threaded rod was used to fill the pulp canal.
Etching of the inner tusk wall was done by swapping hypochlorite on the inner surface. The hypochlorite was rinsed off with saline solution.
After a layer of calcium hydroxy apatite was applied on top of the pulp, the pulp canal and the cleaned crack were filled with glassionomer cement, the tusk surface was sealed with dental composite.
List of equipment
Instruments
Giggli wire + handles
Plyer to cut off the gigli wire
Dremel + extension cable
20 ml syringes (1, 2, 5, 20 and 40 ml)
Nail brush
Tooth brush
Surgical tool set:
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scissors (1 curved 1 straight)
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surgical clamps
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scalpel handle no.3 + blade no.11
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sharp spoon
Sterile dishes to prepare dental restauration products.
Hair dryer
High-speed cutter/acetabulum reamer
Electric drill
Drills (several diameters)
Thread makers (several diameters)
Threaded (nylon) rods (several diameters). See text above)
Disposables
Surgical gloves
Surgical suit
Surgical drapes
Sterile cotton tips
Betadine solution (10%)
Betadine scrub
Saline solution
Chlorhexidine 1%
Etching products:
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3M™ Scotchbond™ Universal Etchant Etching gel
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or Hypochlorite (3%)
Calcium hydroxy-apatite powder (to make a paste) or milled and sterilized Portland cement or calcium hydroxide.
Glass-ionomer cement
Bonding fluid for dental composite (light curing)
Dental composite
2-component epoxy resin
Cotton tips
Non-sterile cotton gauze patches (10x10) to cover the eyes
Sterile cotton gauze patches (10x10)
Leucoplast
Duct tape
Sand paper