Title: Feline odontoclastic resorptive lesion

{{Short description|Oral disease of cats}}
{{Use DMY dates|date=December 2023}}
[[Image:FORL-Molar.jpg|thumb|Feline odontoclastic resorptive lesions on a molar.]]
'''Feline odontoclastic resorption lesion''' ('''FORL''') is a syndrome in [[cat]]s characterized by resorption of the [[tooth]] by [[odontoclast]]s, cells similar to [[osteoclast]]s. FORL has also been called '''Feline tooth resorption''' ('''TR'''), '''neck lesion''', '''cervical neck lesion''', '''cervical line erosion''', '''feline subgingival resorptive lesion''', '''feline caries''', or '''feline cavity'''. It is one of the most common diseases of domestic cats, affecting up to two-thirds.&lt;ref&gt;{{cite journal |last1=van Wessum |first1=R |last2=Harvey |first2=CE |last3=Hennet |first3=P |date=November 1992 |title=Feline dental resorptive lesions. Prevalence patterns |journal=Vet Clin North Am Small Anim Pract |volume=22 |issue=6| pages=1405–1416 |pmid=1455579 |doi=10.1016/s0195-5616(92)50134-6}}&lt;/ref&gt; FORLs have been seen more recently in the history of feline medicine due to the advancing ages of cats,&lt;ref name=&quot;Gorrel&quot;&gt;{{cite web |last=Gorrel |first=Cecilia |title=Feline Odontoclastic Resorptive Lesions |work=Proceedings of the 28th World Congress of the World Small Animal Veterinary Association |date=2003 |url= http://www.vin.com/proceedings/Proceedings.plx?CID=WSAVA2003&amp;PID=6524&amp;O=Generic |access-date=22 October 2006}}&lt;/ref&gt; but 800-year-old cat skeletons have shown evidence of this disease.&lt;ref name=&quot;Foley_2005&quot;&gt;{{cite book |last=Lyon |first=Kenneth F. |chapter=Odontoclastic Resorptive Lesions |editor-last=August |editor-first=John R. |title=Consultations in Feline Internal Medicine |volume=5 |publisher=Elsevier Saunders |date=2005 |isbn=0-7216-0423-4}}&lt;/ref&gt;  Purebred cats, especially [[Siamese (cat)|Siamese]] and [[Persian (cat)|Persian]]s, may be more susceptible.&lt;ref name=&quot;Texas&quot;&gt;{{cite web |last=Dodd |first=Johnathon R. |title=Feline Odontoclastic Resorptive Lesions |work=Small Animal Dental Service |publisher=Texas A&amp;M University Veterinary Medical Teaching Hospital |url= http://vmth.tamu.edu/hospservices/dentistry/FORL.shtml |access-date=22 October 2006 |archive-url= https://web.archive.org/web/20060903201015/http://vmth.tamu.edu/hospservices/dentistry/FORL.shtml |archive-date=3 September 2006 |url-status=dead}}&lt;/ref&gt;

[[image:Tooth Section.svg|thumb|Dental anatomy]]
FORLs clinically appear as erosions of the surface of the tooth at the [[gingiva]]l border. They are often covered with [[Calculus (dental)|calculus]] or gingival tissue. It is a progressive disease, usually starting with loss of [[cementum]] and [[dentin]] and leading to penetration of the [[Pulp (tooth)|pulp]] cavity. Resorption continues up the [[Dental canaliculi|dentinal tubules]] into the tooth crown. The [[tooth enamel|enamel]] is also resorbed or undermined to the point of tooth fracture. Resorbed cementum and dentin is replaced with bone-like tissue.

==Clinical signs==
[[Image:FORL 1.JPG|thumb|left|FORL of the lower third premolar]]
Clinical signs of FORLs are often minimal since the discomfort can be minor. However, there may be subtle signs of discomfort while chewing, as well as anorexia, dehydration, weight loss, and tooth fracture. The lower third [[premolar]] is the most commonly affected tooth.&lt;ref name=&quot;Gorrel&quot; /&gt;

==Cause==
There are two types of FORL. &quot;Type 1&quot; lesions are focal defects often caused by local inflammation. &quot;Type 2&quot; lesions are characterized by a generalized loss of root radiopacity on a dental radiograph. The definitive cause of type 2 FORLs is unknown, but [[histology|histologically]] destruction of the cementum and other mineralized tissue of the tooth root by odontoclasts is seen. It occurs secondary to the loss of the protective covering of the root (the [[periodontal ligament]]s) and possibly to a stimulus such as [[periodontal disease]] and the release of [[cytokine]]s, leading to odontoclast migration.&lt;ref name=&quot;Koret&quot;&gt;{{cite web |last=Bar-am |first=Yoav |title=Ethiopathogenesis of feline odontoclastic resorption lesions |publisher=Koret School of Veterinary Medicine |url= http://ksvm.agri.huji.ac.il/students/seminars/inbar_teller.htm |access-date=22 October 2006}}&lt;/ref&gt; However, FORLs can develop in the absence of inflammation.&lt;ref name=&quot;Gorrel&quot; /&gt; The natural inhibition to root resorption provided by the lining of the root may be altered by increased amounts of [[Vitamin D]], in cats supplied by their diet.&lt;ref name=&quot;Foley_2005&quot; /&gt;
===Risk factors===
Certain breeds are overrepresented, namely: [[Persian cat|Persian]], [[Scottish Fold]], [[Abyssinian cat|Abyssinian]], [[Siamese cat|Siamese]], and [[Russian Blue]]. Other risk factors include: cats that do not chew their food, being fed human leftovers/food, older age, female sex, tap water, raw liver, lack of calcium, and cats without outdoor access.&lt;ref name=&quot;dental&quot;&gt;{{cite book | last=Bellows | first=Jan | title=Feline Dentistry | publisher=John Wiley &amp; Sons | publication-place=Hoboken, NJ | date=2022-01-21 | isbn=978-1-119-56803-2 | pages=224–250}}&lt;/ref&gt;
==Treatment==
Treatment for FORLs is limited to [[Extraction (dental)|tooth extraction]] because the lesion is progressive. Amputation of the tooth crown without root removal has also been advocated in cases demonstrated on a radiograph to be type 2 resorption without associated periodontal or endodontic disease because the roots are being replaced by bone.&lt;ref name=&quot;Carmichael&quot;&gt;{{cite journal |last=Carmichael |first=Daniel T. |title=Dental Corner: How to detect and treat feline odontoclastic resorptive lesions |journal=Veterinary Medicine |date=February 2005 |url= http://www.vetmedpub.com/vetmed/article/articleDetail.jsp?id=146613&amp;pageID=1&amp;sk=&amp;date= |access-date=22 October 2006 |archive-url= https://web.archive.org/web/20060505231509/http://www.vetmedpub.com/vetmed/article/articleDetail.jsp?id=146613 |archive-date=5 May 2006 |url-status=usurped}}&lt;/ref&gt; However, [[Radiography|X-ray]]s are recommended prior to this treatment to document root resorption and lack of the periodontal ligament.&lt;ref&gt;{{cite web |last=Beckman |first=Brett |title=Off with the crown? |work=DVM360.com |publisher=Advanstar Communications |date=1 March 2007 |url= https://www.dvm360.com/view/with-crown |access-date=11 December 2023}}&lt;/ref&gt;

[[Dental restoration|Tooth restoration]] is not recommended because resorption of the tooth will continue underneath the restoration. Use of [[alendronate]] has been studied to decrease progression of existing lesions.&lt;ref&gt;{{cite journal |last1=Mohn |first1=Kenneth |last2=Jacks |first2=Thomas |last3=Schleim |first3=Klaus Dieter |last4=Harvey |first4=Colin |last5=Miller |first5=Bonnie |last6=Halley |first6=Bruce |last7=Feeney |first7=William |last8=Hill |first8=Susan |last9=Hickey |first9=Gerry |title=Alendronate binds to tooth root surfaces and inhibits progression of feline tooth resorption: a pilot proof-of-concept study |journal=Journal of Veterinary Dentistry |date=2009 |volume=26 |issue=2 |pages=74–81 |doi=10.1177/089875640902600201 |pmid=19718970 }}&lt;/ref&gt;

==Differential diagnosis: dental caries==
True [[dental caries]] are uncommon among companion animals.&lt;ref&gt;{{cite web |title=Cavities |publisher=American Veterinary Dental Society |url= http://www.avds-online.org/info/cavities.html |access-date=23 October 2006 |url-status=dead |archive-url= https://web.archive.org/web/20061013002204/http://www.avds-online.org/info/cavities.html |archive-date=13 October 2006}}&lt;/ref&gt; Although it has not been accurately documented in cats, the incidence of caries in dogs has been estimated at 5%.&lt;ref&gt;{{cite journal |last1=Hale |first1=FA |date=June 1998 |title=Dental caries in the dog |journal=J Vet Dent |volume=15 |issue=2| pages=79–83 |pmid=10597155 |doi=10.1177/089875649801500203}}&lt;/ref&gt; The term ''feline cavities'' is commonly used to refer to FORLs; however, saccharolytic acid-producing bacteria are not involved in this condition.

==References==
{{Reflist}}

==External links==
*[http://www.avdc.org/FORL.pdf &quot;Feline odontoclastic resorption lesions&quot;] {{Webarchive|url=https://web.archive.org/web/20061012163737/http://www.avdc.org/FORL.pdf |date=12 October 2006 }} - American Veterinary Dental College position statement.
*[http://www.veterinarypartner.com/Content.plx?P=A&amp;S=0&amp;C=0&amp;A=169 &quot;Feline Oral Resorptive Lesions (FORL)&quot;], from ''Veterinary Partner''

[[Category:Cat diseases]]
[[Category:Veterinary dentistry]]