Elena Carmen NENCIULESCU, DVM, MRCVS, PET STUFF Small Animal Hospital, Bucharest, Romania
Address correspondence to Dr Guzu: firstname.lastname@example.org
History and Clinical Examination Findings
A 7-year-old 5.350 kg neutered male Domestic Shorthair cat was referred for loss of appetite and generalized weakness lasting for 10 days. The owners reported a short episode of hemorrhagic ptyalism (for 24 hours), accompanied by moans and chewing efforts. Previous injection 0.1 mg/kg and prescription 0.05 mg/kg of meloxicam PO, q 24 h, for 2 days only permitted minor transitory food intake improvement. On physical examination, the patient appeared mildly dehydrated (5%) and hyperthermic (39.4°C ). Halitosis with concurrent rostral mandibular swelling were noticed. The swelling was fluctuating, with pain elicited by palpation. A seeping sore spot was observed on the ventral aspect of the mandible (Figure 1).
Moderate bilateral mandibular lymph node enlargement was noted on palpation. Examination on the awake patient was very uncomfortable and the cat only allowed a brief evaluation of the oral cavity. An inflammation of the gingiva surrounding the right mandibular second incisor and the right mandibular canine teeth (402 and 404) was otherwise reported. The remaining physical examination was within normal limits. Biochemistry profile and ionogram results were unremarkable and the FIV/FeLV SNAP test was negative. Complete blood count and serum biochemistry were within normal limits.
A 22G intravenous catheter was placed on the right cephalic vein. The patient was premedicated with methadone hydrochloride 0.2 mg/kg IV and dexmedetomidine 5 µg/kg IV. The patient was induced with propofol 2 mg/kg IV, a 4.5 oral endotracheal tube was placed and then isoflurane 1.5% at a 2L/min rate of oxygen was used for maintenance. Intraoral examination under general anaesthesia and dental charting revealed severe focal periodontitis involving the right mandibular second incisor and the right mandibular canine teeth, with concurrent absence of several incisor teeth. Lateral and occlusal intraoral radiographs were obtained. Selected radiographic views are provided (Figure 2).
Diagnostic Imaging Findings
Radiographic study of the mandible highlighted stage 4c dental resorptive lesions of 402 and 404 (Figure 3). Three root fragments of incisor teeth were noticed (301, 302, 401). An ill-defined bone proliferation with osteolysis involving the surrounding bone was associated with extrusion of the right mandibular canine tooth (404) and concurrent enlarged periodontal space. Cytological examination under light microscope of a transcutaneous fine needle aspirate of the lesion showed degenerated neutrophils, bacteria and some phagocytic activity.
Treatment and Outcome
Within the same general anesthesia, bilateral inferior alveolar nerve blocks (intraoral approach) were performed using a mixture of 0.2 ml lidocaine 2% and 0.8 ml bupivacaine 0.5%. The surgical procedure had 2 parts – an intraoral procedure (dental extractions and biopsy of the diseased mandibular bone) and an extraoral procedure (debridement and reconstruction of the skin). For the first part, with the patient in lateral recumbency 10 mm mucosal incision was performed over the alveolar ridge on the distal aspect of the mandibular canine teeth and was prolonged mesially within the sulcus of the mandibular incisor teeth with a #15c scalpel blade. A mucogingival envelope flap was lifted using a Chompret stripper and a Molt periosteal elevator. Simple extraction of the incisor teeth was performed with a 1.5 mm dental luxator used in a circumferential motion. An external alveolar ostectomy was then performed mesially to the mandibular canine teeth (304 and 404) with a round tungsten carbide burr under irrigation over 50% of the height of the roots. 304 and 404 were extracted using a 3 mm luxator. Curettage of the alveolar sockets and of the remodeled bone was performed using a 3 mm Volkman curette for specimen submission to histology. A minimal alveolar osteoplasty (alveoloplasty) using a round diamond burr under irrigation was eventually performed before closure of the defect with a simple interrupted pattern suture with 5/0 polyglecaprone 25, by moving the flap in translation. For the second part of the procedure, the patient was placed in dorsal recumbency. Clipping and antisepsis (with iodine soap and iodine) of the mandibular and cervical cranial area were carried out before surgical draping. The cutaneous and subcutaneous tissues were debrided over a 3 x 3 cm area, then the site was thoroughly rinsed with a 0.9% NaCl solution (Figure 2). Reconstruction of the defect was undertaken using a submandibular skin flap advanced rostrally. A multi-fenestrated drain was inserted and secured ventrally. A first intent closure of the wound was considered using a simple interrupted pattern suture nylon (Figure 3). Perioperative amoxicillin-clavulanic acid 20 mg/kg was administered by slow IV injection, as well as a postoperative injection of buprenorphine 20 μg/kg IV and meloxicam 0,1 mg/kg SC. Amoxicillin-clavulanic acid 12,5 mg/kg BID for oral relay over a 10 days course and oral meloxicam SID for 5 days were prescribed postoperatively. Placement of a buster collar was recommended during the entire convalescence period.
The patient recovered uneventfully after surgery.
Mandibular swellings may be associated with a fluid collection, such as a cyst, inflammatory seroma, hematoma or, in some cases, a subcutaneous abscess. Development of subcutaneous abscesses may be related with penetrating or migrating foreign bodies, bites or scratches incidents, especially from other cats. A dental etiology (endodontic and/or periodontal disease) must be considered whenever the location involves the oromaxillofacial area. Some local or systemic conditions (neoplastic, inflammatory, infectious, metabolic or endocrine) may trigger the condition. The differential diagnosis summarizing the main causes responsible for mandibular swellings is shown in Table 1.Main DDx of orofacial swellings in cats
The radiographic findings in this case mainly support the hypothesis of a secondary osteomyelitis with regional subcutaneous abscess due to periodontal-endodontic complications of resorptive lesions. The prevalence of dental resorptive lesions varies between 25 and 40% in the general feline population. This rate is as high as 60 to 70% in purebred cats and/or presented within a dentistry department (Girard, 2008 et 2010; Van Wessum et al, 1992). The condition combines heterogeneous, destructive and progressive lesions of the tooth, resulting in ankylosis and replacement of dentoalveolar structures by bony tissue (ghost tooth). The resorption mostly initiates at the level of the radicular cementum and progresses towards the root and/or the dental crown. Involvement of the dental crown is usually associated by a characteristic crenate-looking patching gingiva filling the enamel-dentinal defect corresponding to the progression of a granulation tissue. Many local conditions (e.g. lack of oral hygiene and development of periodontitis, tooth fracture with pulpitis, chronic gingivostomatitis, occlusal trauma) have been documented in the literature, and some systemic causes (e.g. genetic, nutritional) have been suggested as possible triggering factors in the development of the disease in the feline patient. The resulting pulpal exposure (pulpitis) and/or progression towards periodontitis may then be associated with an endodontic-periodontal lesion, significantly decreasing the oral health status. In those cases, an acute pain may sometimes be elicited by finger percussion of the jaw. A characteristic, but not specific jaw trembling reflex may then be observed. The earliest affected teeth statistically reported in the literature are the mandibular third premolars (307 and 407). (Ingham, 2001) However, all teeth may be involved, with progression towards a generalized disease possible in some individuals. Typical but non-pathognomonic presentation is possible in canine teeth (dental extrusion or occult root destruction). Several clinical and radiological classifications have been proposed by the American Veterinary Dental College (AVDC) in regard to the location and severity of the lesions. (DuPont, 2002) A similar condition has also been described in humans and dogs, but is slightly different from the feline presentation. (Heithersay, 2007; Kim, 2013; Nemec, 2012; Peralta, 2010) Despite many evoked tracks (traumatic, metabolic, infectious, nutritional or genetic), the etiology of the feline tooth resorption remains rather vague and no prophylactic approach is available to date. (Okuda & Harvey, 1992; Reiter, 2005; Girard, 2008) It seems that metabolism of vitamin D may play a key role in the odontoclastic activation process. (Booij-Vrieling, 2009)
When facing an oromaxillofacial swelling, it is important to consider the specificity of the area, in particular the proximity of oral, nasal, orbital, nodal, vasculo-nervous or salivary structures. Reclining the lips and tongue, allowing a more detailed inspection of the gingiva, vestibule, floor of the mouth, as well as the ventral and lateral aspects of tongue is therefore essential. Fine needle aspiration should be performed whenever possible as cytological examination could bring additional information that could further guide diagnostic and therapeutic approach. Evidence shows a favorable predictive value of about 69% even in case of neoplastic conditions. (Ghisleni, 2006) The histopathological examination remains cornerstone, in order to confirm the diagnosis given the high rate of secondary infection in or near the oral cavity. According to the information gathered during the clinical examination and the localization of the lesion, different diagnostic imaging tools could be considered. The conventional extraoral radiography has two major disadvantages compared to the dental radiography: superimposed images and lack of sensitivity in the exploration of dental conditions (Chapnik, 1989). The CT scan provides good information in regard to the extension of any swelling condition. However, only 42 to 57% of the dental resorptive lesions are diagnosed on the CT scan when compared to the intraoral radiography (Lang et al, 2016) Therefore, dental radiographs still constitute the gold standard imaging method to diagnose tooth resorption. New diagnostic imaging devices such as the cone-beam computed tomography scan (CBCT) might be an interesting alternative in the exploration of these dento-alveolar conditions in the future. (Naitoh et al, 2010 ; Soukup, 2015 ; Creanga, 2015)
Extraction of the affected tooth by resorptive lesions remains the treatment of choice. (DuPont, 2005) According to the topography of the lesions, conservative techniques (glass ionomer restoration) have historically been described in early forms, localized to the collar and dental crown. However, the outcome for those teeth remained poor, with inevitable progression of the disease in the majority of the cases. In advanced forms, with associated root ankylosis, and for which tooth extraction would be an additional trauma for healthy tissue (e.g. high risk of mandibular fracture), crown-root amputation may constitute an acceptable alternative. The use of dental rotary instruments is mandatory. However, this option remains controversial for FIV or FeLV positive patients, as potentially at high risk of osteomyelitis, and systemic infectious spread. Specific cases affected by internal or localized forms to the root apex may be eligible to standard root canal treatment +/- apicoectomy as in other species, but fast progression of the disease known in the feline patient is a negative prognostic factor and therefore extraction is the only therapeutic option.
When treating perioral wounds, choosing between first, second or even third intention healing strategies, the following must be taken into consideration: the size of the defect, the possible infection associated, the risk of tissue contraction, fibrosis and dehiscence, as well as more specific patient or systemic considerations. When infected, a surgical wound debridement with abundant sterile rinsing of the area should be considered first. It is generally accepted that leaving a wound heal by second intention is not recommended near a sphincter, or any orbicular muscle such as those constituting the lips due to the wound contraction associated, and possible restricted mobility. (Ishii & Byrne, 2009) Excessive tension should be avoided by proper use of reconstructive techniques and more specifically locoregional flaps described in the oromaxillofacial area. (Guzu et al, 2021) A random flap advanced rostrally using lateral releasing incisions and incremental subcutaneous dissection allows for simple reconstruction of the cutaneous defect in the intermandibular area. (Swaim in: Verstrate, 2012) Placement of walking sutures reduces the dead space between the flap and the underlying tissue while decreasing the tension on the wound. Depending on the different size and location of the defect, axial flaps (labial, angular oris), free cutaneous flaps, or even free vascularized flaps using microvascular anastomosis techniques are also appropriate surgical treatment options. (Tong & Simpson, 2012; Smith, 1991; Smeak, 1992; Bradford, 2011, Walsh & Gregory in: Verstraete, 2012) The survival of all those flaps does not rest on the presence of an underlying granulation tissue, but simply on the absence of major contamination. Drainage is generally recommended, in order to reduce the risk of fluid collection formation (hematoma, seroma, infection) which may compromise the vitality of the flap. (Wardlow & Lanz in: Tobias, 2012)
Dental resorptive lesions constitute a potential source of discomfort, affecting approximately 30% of the cats in the general population. Early diagnosis and treatment remain particularly challenging for any practitioner. Despite many hypotheses regarding the initiating factors leading to its development, no preventive or conservative strategies are available to provide long-term control of the disease. Extraction of the affected teeth is the gold standard treatment, capable of slowing down the extension of the lesions to the adjacent teeth and preventing possible infectious complications. A better understanding of the mechanisms associated with the formation of dental resorptive lesions may improve its medical and surgical management in the future.
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