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\begin{document}

\title{Complications of Equine Cheek Teeth Extractions}



\author[1]{Paddy Dixon}%
\affil[1]{Private Surgical Consultant}%


\vspace{-1em}



  
  \date{May 17, 2024}


\begingroup
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\selectlanguage{english}
\begin{abstract}
Due to the length of the reserve crown and roots of equine cheek teeth,
especially in younger horses, their extraction (exodontia) can be a
challenging procedure with the potential for many types of
post-extraction complications to develop. The prevalence of
post-extraction complications is greatly influenced by the exodontia
technique used, with unacceptably high levels of complications with the
traditional repulsion technique and conversely, low levels of
complications with oral extraction performed by skilled operators.
Recent objective studies on post-exodontia problems in horses have also
highlighted some risk factors for the development of post-extraction
problems including exodontia of rostral mandibular teeth in young
horses, and exodontia of teeth with apical infections The recent
recognition that some non-healing post-extraction equine alveoli suffer
from a disorder very similar to dry socket in humans, may help
clinicians to recognise, treat and possibly help prevent this disorder.%
\end{abstract}%



\sloppy


\textbf{Complications of Equine Cheek Teeth Extractions}

\textbf{PM Dixon Edinburgh}

\textbf{Introduction}

Historical aspects of equine cheek teeth exodontia techniques and
extraction complications

The type and prevalence of equine post dental extraction problems are
closely related to the dental extraction (exodontia) technique used as
reviewed by Dixon \emph{et al.} (2009), Earley \emph{et al.} (2013),
Carmello \emph{et al.} (2020), Kennedy \emph{et al.} (2020) and Reardon
(2022). Oral extraction in conscious, cast horses restrained by ropes,
or under chloroform anaesthesia, or occasionally in standing horses
restrained by twitches and leg ropes were widely practiced in the 1800s
and early 1900s with obvious welfare problems in non-anaesthetised
horses (Easley 2022). Nevertheless, many excellent equine oral
extraction instruments and oral speculums were developed at those times.
In the mid-1900s, for reasons unknown to the author, the practice of
cheek teeth repulsion under chloroform and later, halothane general
anaesthesia largely replaced oral extraction and became the standard
equine cheek teeth exodontia technique \textbf{(Fig 1)} . The repulsion
technique, with its very high reported complication rate of up to 67\%
(Dixon \emph{et al.} 2000) or 80\% (Carmello \emph{et al.} 2019)
remained the standard cheek tooth exodontia technique until the 1990s.

The use of the (standard) lateral buccotomy cheek teeth exodontia
technique in the late 1900s caused a reduced prevalence but a different
range of post-operative complications (O'Neill \emph{et al.} 2011), as
well as always requiring general anaesthesia with its attendant costs
and risks. The advent of effective and safe equine sedation drugs
facilitated the (re)introduction of standing oral extraction in the
1990s (Dixon \emph{et al.} 2005; Tremaine 2010) using similar oral
speculums and extraction instruments developed over 100 years
previously. The later introduction of effective regional local
anaesthetic techniques (Tremaine, 2007) further enhanced oral extraction
techniques, that remains the current equine exodontia technique of
choice.

However, oral exodontia requires the presence of a sufficiently strong
clinical crown on the affected tooth. The development of less invasive
exodontia techniques for teeth with incomplete clinical crowns,
including minimally invasive (Steinmann pin) repulsion, minimally
invasive transbuccal technique (MITT) (also termed minimally-invasive
transbuccal extraction {[}MTE{]}) and intra-oral dental sectioning have
reduced the prevalence of post-extraction problems of teeth with an
incomplete clinical crown as compared to the standard repulsion
technique (Langeneckert \emph{et al.} 2015; Kennedy \emph{et al.} 2020;
Carmello et al 2020). Regardless of the exodontia technique that is
used, post-extraction problems can still occur even following careful
extractions by skilled veterinarians (Kennedy \emph{et al.} 2020;
Geigert and Bienert 2020).

Post-extraction alveolar management

Apical infection \textbf{(Fig 2)} is the most common indication for
cheek teeth exodontia, being the reason for 62\% of 428 extractions in a
recent study (Kennedy \emph{et al.} 2020). Exodontia of apically
infected teeth causes a bacteraemia with potential pathogens, including
anaerobes (Kern \emph{et al.} 2017). Many clinicians administer
pre-operative antibiotics (e.g., penicillin and an aminoglycoside)
including to help prevent the rare spread of bacteria from infected
teeth to distant sites, that can cause infections such as meningitis
(Bach \emph{et al} . 2014; Arndt \emph{et al.} 2021). When infection of
the supporting bones is present, longer-term post-extraction antibiotic
therapy is justified. There is less consensus on the routine use of
post-extraction antibiotic therapy in other exodontia cases.

Following exodontia, the alveolus should be digitally and visually
(using a dental mirror or oral endoscope) examined, as should the apical
aspect of the extracted tooth to ensure that no dental fragments remain
in the alveolus. If any doubt remains, and always following repulsion
techniques or where the apex of the tooth is not intact, post extraction
radiography should be performed to ensure that no intra-alveolar dental
(or alveolar bone fragments) remain. Any such identified fragments
should be immediately removed digitally or using long, right-angled
equine dental picks with adjustable heads under visual guidance, and
with use of suction of intra-alveolar blood to allow visualisation of
mandibular alveoli. If suitable picks are unavailable, high pressure
lavage of the alveolus using an equine dental syringe may remove
unattached bone or dental fragments. Formation of a new blood clot
should now be encouraged, if necessary, by alveolar curettage.

Optimal post-extraction healing will occur in an alveolus that did not
have significant pre-existing alveolar bone infection, which has not
sustained excessive exodontia-related alveolar bone damage, does not
contain dental or bone fragments and which contains a large
post-extraction blood clot. The alveolar blood clot should be protected
from masticatory forces and food impaction by placing packing material
(e.g., polysiloxane, acrylic or surgical swabs {[}gauze{]} impregnated
with antibiotics, honey or dilute antiseptics) in the more occlusal
(e.g., one third) aspect of the alveolus. Excessively deep alveolar
packing will mechanically reduce or even prevent alveolar healing. Some
clinicians have used antibiotic-impregnated surgical swabs in the more
occlusal half of the alveolus to help treat existing and help control
post-operative alveolar bone infection (Kennedy \emph{et al.} 2020). The
risk of bacterial antibiotic resistance development must be considered
with such local antibiotic therapy. The use of surgical swabs soaked in
concentrated antiseptic solutions such as Povidine iodine may risk
causing chemical irritation and delayed alveolar healing.

No large objective studies have determined which post-extraction
alveolar management is optimal. However, anecdotal evidence indicates
that just placing packing material in the alveolus following exodontia
and allowing this material to spontaneously dislodge later, is
unsatisfactory. This is especially true following exodontia of apically
infected Triadan 06-08 mandibular cheek teeth in younger horses
(Kennedy\emph{et al.} 2020; Giegert and Bienert 2021). Instead, the
post-extraction alveolus should be actively managed until healing is
complete or near complete. The alveolar packing inserted immediately
post extraction should be removed about 7-10 days later, and the
alveolus digitally examined to assess if it is lined by smooth
(developing granulation) tissue over all its surfaces. Rough areas of
exposed bone such as caused by alveolar sequestration or \emph{dry
socket} are readily palpated and if these bony areas are loose (i.e. are
sequestrae rather than dry socket), they should be removed digitally or
using picks.

If the alveolus appears to be healing normally at this first
re-examination, it should be gently lavaged, without dislodging the
blood clot. The occlusal aspect of the alveolus should be repacked
(using less packing material on this occasion) and the alveolus
re-examined 1- 2 weeks later to further assess alveolar healing and in
particular, for evidence of delayed sequestration. As noted, the most
rigorous management is needed following extraction of younger mandibular
teeth with apical infection and such cases should have repeated alveolar
examinations until healing is very advanced.

\textbf{Post-extraction disorders}

\textbf{Damage to adjacent teeth}

Due the normal angulations and curvatures of the cheek teeth reserve
crowns in the rostro-caudal plane, and/or due to improper repulsion
punch placement, the punch may damage adjacent teeth (Dixon \emph{et
al.} 2000), unless its position and angulation in the\emph{rostro-caudal
plane} is carefully monitored by intra-operative radiography during
repulsion. Damage to adjacent teeth can less commonly occur during
sectioning of teeth with damaged clinical crowns or during dental
luxation using an elevator and mallet when using the MITT. If the apical
blood supply of adjacent teeth is iatrogenically damaged, this will
cause death of the tooth.

\textbf{Traumatic alveolar damage}

Movement of the punch in a \emph{medial or lateral plane} during
repulsion may markedly damage the alveolus and supporting bones. When
repulsing a mandibular cheek tooth, the punch may penetrate or even
fracture the mandible, lingually or buccally to the tooth. Similarly,
when repulsing a maxillary cheek tooth, the punch may penetrate or
fracture the hard palate or the buccal aspect of the adjacent maxillary
bone. Such damage can predispose to sequestration and/or local soft
tissue infection.

Due to the angulation of the caudal cheek teeth reserve crowns and the
presence of the facial crest, it is not possible to perform the MITT
extraction on all cheek teeth positions. Additionally, when teeth are
being elevated (loosened) with a transbuccal elevator and mallet, the
elevator will always cause local alveolar bone damage. Additionally, the
angle of introduction of the elevator into the alveolar spaces is not
always optimal and can cause local alveolar bone damage due to the
restriction of using a single cannula site.

The use of partial crown removal (partial coronectomy) to facilitate
mesio-distal (rostro-caudal) dental crown movement when using cheek
teeth separators (Rice and Henry, 2018) or full sectioning of teeth with
damaged clinical crowns, dilacerated roots or apical hypercementosis
also carries a risk of causing direct traumatic or thermal (if using
non-water cooled equipment) alveolar bone damage. This can cause delayed
sequestration and infection of the injured bone.

\textbf{Retention of dental fragments}

Standard repulsion of apically infected teeth tends to drive the punch
into the diseased (less mineralised) apex and adjacent reserve crown and
can cause peripheral fragments of the reserve crown to fracture off and
remain attached to the alveolar wall (\textbf{Fig 1} ). These fragments
need to be identified (including by routine post-extraction clinical and
radiographic examinations following repulsion) and removed, else they
will likely result in a non-healing alveolus. Dental fragments, except
for long mandibular roots in older horses (\textbf{Fig 3} ) are less
commonly retained following other exodontia techniques

\textbf{Damage to facial nerves, vasculature and parotid duct}

The standard lateral buccotomy extraction technique has largely been
discontinued due to its invasive nature, necessitating long incisions in
the cheeks and/or supporting bones with risk of damaging buccal nerve
branches, facial vasculature or the parotid salivary duct and always
requiring general anaesthesia. There is a low risk of such damage with a
carefully performed MITT.

\textbf{Infraorbital Nerve Damage}

Damage to the infra-orbital canal and its nerve can occur during
maxillary cheek tooth repulsion, especially in young horses where the
infra-orbital canal sits immediately medio-dorsal, or dorsal to the
apical aspect of the alveolus. In many young horses, it is difficult to
understand how such nerve damage is avoided during a standard repulsion.
If the infraorbital nerve is damaged by repulsion techniques, clinical
signs may occur within hours in a proportion of horses, and can include
violent headshaking, distress, and rubbing (even excoriating) the
ipsilateral nostril off adjacent structures. Such cases usually do not
respond to corticosteroid, non-steroidal anti-inflammatory, or opiate
therapy, but may respond in the short-term to acetylpromazine therapy.
Thankfully most cases show spontaneous resolution of clinical signs
within 1 to 2 weeks of nerve injury. However, some cases of trigeminal
damage can cause longer term headshaking (Ogden \emph{et al.} 2022).
Infraorbital nerve damage is much less likely following Steinmann pin
repulsion, but long term signs of clinical trigeminal neuropathy can
rarely occur following use of this technique.

\textbf{Surgical site infection}

Due to their inevitable contamination, infection of trephine repulsion
sites is common but usually self-limiting. Prolonged non-healing of
cutaneous repulsion tracts should prompt an examination for the presence
of intra-alveolar dental or bone fragments, or of saliva or food from
oral leakage. Local infection and delayed healing can occur at standard
buccotomy wounds (O'Neill \emph{et al.} 2011) but rarely at MITT sites.

\textbf{Sequestration of alveolar wall}

The most common complication following oral extraction is sequestration
of segments of alveolar bone with or without concurrent alveolar
infection. Kennedy \emph{et al.} (2020) found alveolar sequestration to
be the most common post-extraction problem and was identified in 38/428
cheek teeth extractions (including 343 oral extractions). Clinical signs
of alveolar disease were present in 17 of these cases (4\% of 428 cases)
but in 15 cases (3.5\%) the (usually smaller) sequestrae that were
detected on routine post-extraction alveolar examinations did not cause
a detectable clinical problem (Kennedy \emph{et al.} 2020). Giegert and
Bienert (2021) found a 6.6\% (20/302 cases) prevalence of clinical
post-extraction complication with mandibular cheek teeth oral
extractions, with 18 of 20 complications being alveolar sequestration
and infection, including sequestration of the complete alveolar wall.

Due to the great length (up to 9cm long) of equine cheek teeth reserve
crowns, high and prolonged mechanical forces are required to break down
their periodontal membranes. High forces are also required to deform the
layer of dense bone (i.e., bundle bone or cribriform plate --
radiologically termed the \emph{lamina dura {[}denta{]}} ) that lines
the alveolus and compress it into the underlying spongy bone to enlarge
the periodontal space and so allow dental movement and later extraction
(\textbf{Fig 4} ). This necessary alveolar bone deformation can cause it
to fracture deeply and/or may disrupt its local blood supply. The
partial coronectomy technique (Rice and Henry, 2018) may less
traumatically create additional intra-alveolar space to facilitate
extraction.

Fragments of fractured alveolar bone may be detected immediately
following exodontia if the fractured bone segment is displaced by
exodontia forces. More commonly, alveolar fragments are recognised a
week or more later (\textbf{Fig 5} ), especially if caused by
extraction-induced loss of blood supply to a local area of fractured
alveolar bone. The presence of alveolar sequestrae prevents alveolar
healing and can acts as a nidus of infection, often leading to alveolar
infection and even osteomyelitis of the supporting bones (\textbf{Fig 6}
). Such infected alveoli are usually malodorous and on digital palpation
have areas of exposed bone and contain loose sequestrae. Alveolar
sequestration occurs more commonly in mandibular as compared to
maxillary cheek teeth, as is also the case in human dentistry
(Chiapasco\emph{et al} . (1993), possibly related to differences in the
thickness and rigidity of these bones and their blood supply. The
effects of gravity in retaining alveolar bone sequestrae and infected
exudate in mandibular as compared to maxillary alveoli may also be
significant.

\textbf{Alveolar bone infection and osteomyelitis of the supporting
bones}

The most common indication for equine cheek teeth exodontia is infection
of the tooth apex that is usually caused by mixed anaerobic bacterial
infections (with concurrent infection of some or all pulp horns, the
adjacent periodontal membranes and alveolar bone). Extraction-related
damage to the alveolar bone may allow more extensive bone infection by
these pathogens to develop. Consequently, post-extraction complications
are higher following extractions of apically infected as compared to
fractured teeth without clinical apical infection (Kennedy \emph{et
al.}2020) and especially in horses with pars pituitary intermedia
dysfunction. Concurrent alveolar sequestration is common with alveolar
and supporting bone infections and it may not be possible to determine
which came first (\textbf{Fig 6} ).

If the supporting mandibular or maxillary bones are swollen and painful
on palpation, the alveolus is obviously infected and will usually
contain malodorous exudate. Systemic and possibly local antibiotic
therapy should be administered to such cases along with removal of
sequestrae and alveolar lavage. Repeat examinations, even weeks later
may show development of new sequestrae that also must be removed.
Because many of the bacteria involved in dental infections are partial
or full anaerobes and possibly 50\% cannot be conventionally cultured,
broad-spectrum antimicrobial treatment that is effective for anaerobic
infections should be administered to such cases. Further examinations
including imaging to assess the degree of bone infection and detect new
sequestrae should be performed until the alveolus has complete
granulation tissue cover indicating alveolar healing (\textbf{Fig 7} ).

\textbf{Oro-maxillary, oro-nasal and oro-cutaneous fistulae formation}

The presence of a food-containing nasal discharge following exodontia is
indicative of an oro-nasal (\textbf{Fig 8} ) or oro-maxillary
(\textbf{Fig 9} ) communication and likewise the presence of food at a
repulsion site indicates the presence of an oro-cutaneous communication.
By necessity, repulsion always damages the apical aspect of the alveolus
and if the alveolar packing is lost before the damaged alveolar apex has
healed, this causes oro-maxillary, oro-nasal or oro-cutaneous tracts
that eventually may epithelialise and become fistulae. This is in total
contrast to non-repulsion techniques that preserve the alveolus. Damage
to the alveolar apex is especially marked when a traditional (large)
dental punch is used, and one study showed an 11\% prevalence of
oro-maxillary or oro-nasal fistulation following repulsion
(Carmello\emph{et al} . 2020). In contrast, the careful use of a fine
punch (e.g., a 5mm diameter Steinmann pin) seldom causes fistulae,
especially if inserted through a pre-existing apical draining tract.

When loosening maxillary cheek teeth using the MITT technique, care must
be taken that the dental elevator is not punched too far in an apical
direction, or at a later stage of MITT, that the drill bit does not
penetrate the apex of the alveolus into the overlying sinus or nasal
cavity. Greatly varying prevalences of oro-maxillary fistulae have been
reported following MITT from 29\% (Carmello \emph{et al.} 2020), 26\%
(Reichert \emph{et al.} 2014) to 2\% Langeneckert \emph{et al.} 2015).

For treatment, these tracts need to be lavaged of food and debrided of
any epithelial lining. A more robust barrier e.g., an acrylic alveolar
prosthesis, can be placed between adjacent teeth to prevent further
alveolar food ingress into the alveolus until it heals (Dixon, 2020).

\textbf{Non-healing alveolus with exposed alveolar bone (``Dry
socket'')}

The presence in non-healing alveolus of exposed, often tan-coloured,
alveolar bone that \emph{remains firmly attached} to the remaining
alveolar bone and which remains vital beneath the usually discoloured
exposed layer, is termed \emph{dry socket} (\textbf{Fig 10} ). Dry
socket is the most common (and a very painful) post-exodontia problem in
humans where it is usually caused by absence of an adequate
intra-alveolar blood clot to protect the exposed alveolar bone. Dry
socket has only recently been recognised in horses (Horbal \emph{et al.}
2018; Kennedy\emph{et al.} 2020), but possibly all non-healing alveoli
without obvious infection or sequestrae could be considered to be
affected by this disorder. Such alveoli, that are often painful, need
repeated monitoring and packing to cover the exposed alveolar bone. It
may take many weeks for the superficial bone layer to be shed or
resorbed and the underlying healthy bone to then become covered in
granulation tissue to allow alveolar healing.

\textbf{Continuation of unilateral nasal discharge}

The failure of dental sinusitis cases to resolve following exodontia may
be related to one of the above described alveolar disorders, but is much
more likely to be caused a residual sino-nasal problem (Dixon \emph{et
al} . 2019). Such cases should have the affected alveolus examined and,
if it contains sequestrae and/or is infected, or if it has a
communication with the sinus, these disorders should be treated.
However, the more likely causes for non-response of dental sinusitis are
the presence of inspissated exudate or bone sequestrae in the affected
sinuses or intercurrent nasal disease including nasal conchal bulla
infections (Dixon \emph{et al} . 2019, 2021).

\textbf{References}

Arndt, S., Kilcoyne, I., Heney, C. M., Wong, T. S., \& Magdesian, K. G.
(2021). Bacterial meningitis after dental extraction in a 17-year-old
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Bach, F.S.~,~ Bodo, G.~,~ Kuemmerle, J.M.,~ Bienert-Zeit, A.,~ Hainisch,
E.K.~,~ Simhofer H.~ (2014) Bacterial meningitis after sinus surgery in
five adult horses\textbf{.} \emph{Vet Surg} ,~\textbf{43} ,~697-703.

Caramello, V., Zarucco, L., Foster, D., Boston, R., Stefanovski, D. and
Orsini, J. Equine cheek tooth extraction: comparison of outcomes for
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,181--6. doi: 10.1111/evj. 13150 .

Chiapasco, M., De Cicco, L. and Marrone, G. (1993) Side effects and
complications associated with third molar surgery. \emph{Oral Surg.,
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oral surgery. \emph{Vet. Clin. N. Am.:} \emph{Equine Pract} .\textbf{24}
, 499--514.

Dixon P, Tremaine W, Pickles K, Kuhns L, Hawe C, McCann J, et al. (2000)
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doi: 10.2746/04251640077656 3581

Dixon, P., Dacre, I., Dacre, K., Tremaine, W., McCann, J. and Barakzai,
S. (2005) Standing oral extraction of cheek teeth in 100 horses
(1998-2003). Equine Vet J. \textbf{37} , 105--12. doi:
10.2746/0425164054223822

Earley, E.T., Rawlinson, J.E. and Baratt, R.M. (2013) Complications
associated with cheek tooth extraction in the horse\emph{. J. Vet. Dent}
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Dixon, P. M. (2020). Treatment of equine oro-nasal and oro-maxillary
fistulae.~\emph{Equine Vet Educ.} ~\textbf{32} , 471-478.

Gergeleit, H. and Bienert-Zeit, A., (2020). Complications Following
Mandibular Cheek Tooth Extraction in 20 Horses.~\emph{Frontiers Vet
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Horbal. A., Reardon. RJM, Froydenlund T, Jago RC, Dixon PM. (2019). Head
and neck abscessation and thrombophlebitis following cheek tooth
extraction in a pony. \emph{Equine Vet Educ} . \textbf{31} , 523-529.
https://doi.org/10.1111/eve.12900

Kennedy, R., Reardon, R.J., James, O., Wilson, C. and Dixon, P.M.,
(2020). A long-term study of equine cheek teeth post-extraction
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,~\textbf{52} , 811-822. doi: 10.1111/evj.13255

Kern, I., Bartmann, C.P., Verspohl, J., Rohde, J., and Bienert-Zeit. A.
(2017) Bacteraemia before, during and after tooth extraction in horses
in the absence of antimicrobial administration. \emph{Equine Vet J}
.\textbf{49} , 178--82. doi: 10.1111/evj.12581

Langeneckert, F., Witte, T., Schellenberger, F., Czech, C., Aebischer,
D., Vidondo, B. and Koch, C. (2015) Cheek tooth extraction via a
minimally invasive transbuccal approach and intradental screw placement
in 54 equids. \emph{Vet. Surg} . \textbf{44} , 1012--1020.

Ogden, N., Thomas, H., Carslake, H. and Kane-Smyth, J. (2022) Trigeminal
neuropathy in two horses following trauma to the infraorbital and mental
nerves. \emph{Equine Vet Educ. In Press} .
https://doi.org/10.1111/eve.13700

O'Neill, H.D., Boussauw, B., Bladon, B.M. and Fraser, B.S. (2011)
Extraction of cheek teeth using a lateral buccotomy approach in 114
horses (1999--2009). \emph{Equine Vet} J. \textbf{43} , 348--353.

Rice, M, and Henry, T. (2018) Standing intraoral extractions of cheek
teeth aided by partial crown removal in 165 horses
(2010--2016).\emph{Equine Vet J.} \textbf{50,} 48--53. doi:
10.1111/evj.12727.

Tremaine, W.H. (2004) Oral extraction of equine cheek teeth.\emph{Equine
Vet Educ.} \textbf{16} , 151--158. doi: 10.1111/j.2042-3292.2004.tb00287

Tremaine, W.H. (2007) Local analgesic techniques for the equine
head.\emph{Equine Vet Educ.} \textbf{19,} 495--503.

\textbf{Figure Legends}

\textbf{Fig 1.} The left image shows a maxillary cheek tooth being
repelled under general anaesthesia. The right image shows typical damage
to a repulsed tooth, with its apical area extensively fractured that
predisposes to retention of dental fragments.

\textbf{Fig 2} . Radiograph of an apically infected mandibular Triadan
08 in a young horse with a thin metallic probe inserted into a ventral
draining tract. Note the extensive bone changes at the caudal and apical
aspects of the alveolus (arrows). Exodontia of this tooth has a higher
risk of post-extraction problems as this is a rostral mandibular cheek
tooth, is apically infected and in a young horse.

\textbf{Fig 3.} These extracted Triadan 10 mandibular cheek teeth are
from two mature horses that had bilateral Triadan 10 developmental
displacements and long term periodontal disease. Exodontia of these
teeth with long curved tapering roots resulted fracture of one caudal
(distal) root as shown in the left image and one rostral (mesial) and
one caudal (distal) root in the teeth as shown in the right image.

\textbf{Figure 4.} This radiograph of normal rostral mandibular cheek
teeth in a young horse has the periodontal space rostral to the Triadan
07 indicated by a yellow arrow. The adjacent lamina dura (bundle bone or
cribriform plate) (white arrow) overlies the larger expanse of spongy
bone (SB).

\textbf{Fig 5.} The left image shows a non-healing, post-extraction
alveolus with thin alveolar sequestrae (arrows) visible in its lumen. A
small granuloma-type lesion is present on the top left of image. The
right image shows some of the sequestrae that were removed from this
alveolus.

\textbf{Fig 6} . Left: This parasagittal CT image is of a horse with
alveolar osteomyelitis and sequestration following exodontia of 408.
Note the gross soft tissue swelling overlying the affected alveolus
(white arrow), alveolar thickening and remodelling and a large
sequestrum of its lateral wall (star). Right: this transverse CT image
of this case in a slightly different plane, also shows the overlying
soft tissue swelling (white arrow), gross alveolar wall remodelling and
an intra-alveolar sequestrum (yellow arrow). The alveolus of (maxillary)
Triadan 208 which underwent exodontia the previous year is fully healed.

\textbf{Figure 7} . The left image shows the mandible in Fig 6 with
post-exodontia osteomyelitis, sequestration, overlying soft tissue
swelling and widespread alveolar bone changes. The right CT image of
this same site was obtained 8 months later when the infection had
resolved. It shows a shortened mandible with reformation of its walls
and the 408 alveolar lumen filled with osteoid material.

\textbf{Fig 8} . This transverse CT image taken following exodontia of
206 shows a large oro-nasal fistula filled with food (arrows). There
also is almost total loss of the surrounding alveolus and supporting
bone that will make repair of this fistula problematic. (Fig courtesy of
Dr Eric Parente).

\textbf{Fig 9.} These intra-oral images show a large oro-maxillary
(oro-sinus) fistula at the site of a repulsed 109 (arrows). The dental
mirror in the right image shows the fistula to be filled with forage.
This neglected fistula is expanding in a palatal direction and will be
increasingly difficult to treat.

\textbf{Fig 10.} This oral endoscopic image shows a non-healing alveolus
that contains no blood clot, has exposed, discoloured porous-appearing
bone (yellow arrow) over much of its surface with some forage fibres
visible (black arrow). Healthy granulation tissue is only present at the
occlusal aspect of the alveolus. Such alveoli need assessment to
determine if the exposed bone is loose (i.e., is an alveolar sequestrum)
or whether it is affected by ``dry socket'' as was the case for this
alveolus.\selectlanguage{english}
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