Mandibular fracture repair techniques in cats: a dentist's perspective.

PRACTICAL RELEVANCE: Feline head trauma injuries are common in general practice, often resulting in mandibular fracture. An understanding of the recent advances in the field of mandibular fracture repair will facilitate evidence-based decision-making in clinical practice. CLINICAL CHALLENGES: Feline maxillofacial and oral anatomy brings unique challenges in comparison with dogs. It has been commonplace to adapt techniques and equipment that are better suited to other body regions or are species-inappropriate for use in feline maxillofacial surgery, and this has traditionally resulted in high morbidity. AIMS: This review presents an overview of the diagnosis of, and decison-making for, maxillofacial trauma in cats, specifically with reference to the feline mandible. The challenges associated with the management of these injuries are presented. Techniques for repair that can be employed in general practice, as well as more advanced surgical options, are discussed, as well as the indications for invasive vs non-invasive management. Underutilised methods involving composite dental materials and their versatility for the repair of mandibular fractures in cats, and miniplates for caudal mandibular fractures in cats, are specifically covered, as well as other recent advances in the field, including three-dimensional printing and custom-printed implants. EVIDENCE BASE: Management of feline facial fractures is an often neglected topic, with very few published studies choosing to focus on head trauma outcomes in cats. Where available, however, this review draws on the published literature, as well as the authors' own clinical experience.

Rostral mandibulectomy for the management of trismus in a cat.

CASE SUMMARY: A 5-year-old domestic shorthair cat was evaluated for weight loss and poor coat condition due to an inability to open its mouth (trismus) following head trauma 2 months previously. Contrast CT, electromyography and temporal muscle biopsy identified findings consistent with muscle atrophy, denervation and degeneration. Conservative treatment failed to improve the trismus so a rostral mandibulectomy was performed. Following surgery, the patient resumed normal grooming behaviour and was able to eat soft food unaided. The cat re-presented 5 months postoperatively at which time its body condition had improved; however, episodes of sneezing had been noted. An oronasal fistula was diagnosed and treated successfully with a silicon nasal septum button. Follow-up at 30 months reported an excellent outcome. RELEVANCE AND NOVEL INFORMATION: Management of trismus with rostral mandibulectomy may be associated with a good return to function, including prehension and ingestion of food, and restoration of normal grooming activity. Rostral mandibulectomy could be considered for animals with trismus for other aetiologies such as masticatory myositis where other management options are not available.

A longitudinal assessment of periodontal disease in Yorkshire terriers.

BACKGROUND: Periodontal disease is the most common oral disease of dogs and has been associated with systemic disease. The purpose of the present study was to determine the extent of periodontal disease in a population of Yorkshire terrier dogs with and without a tooth brushing regimen. Each dog was assessed under general anaesthesia two to five times between 37 and 78 weeks of age. The extent of gingivitis and periodontitis was ascertained for every tooth in the mouth. Gingivitis was measured using time to bleeding on probing, and periodontitis was based on extent of clinical attachment loss (probing depth, gingival recession and furcation exposure). RESULTS: Of the 49 dogs assessed at 37 weeks of age, 98% had at least one tooth or aspect with early periodontitis (PD2, < 25% attachment loss). The average percentage of teeth with periodontitis in the mouth was 29.6% with 95% confidence interval (23.6, 36.4). The odds of early periodontitis was 2.74 (2.23, 3.37) times higher at 78 weeks of age compared to 37 weeks of age. The canine teeth had a significantly higher probability of periodontitis compared to all other tooth types at both 37 and 78 weeks of age (p < 0.001). In addition, at the same time points, the incisors had a significantly higher probability of periodontitis compared to the molars and premolars (p < 0.001). CONCLUSIONS: Breeds of dog that are susceptible to developing periodontitis, such as Yorkshire terriers, require effective treatments for the prevention of periodontal disease from a young age. Although tooth brushing is one of the most effective methods when it comes to preventative homecare, this is not always realistic, as was found in this study. Therefore alternative ways to retard or prevent plaque accumulation that are practical for both dogs and their owners are required.

Location and distribution of craniomaxillofacial fractures in 45 cats presented for the treatment of head trauma.

OBJECTIVES: The aim of this retrospective study was to describe the location and distribution of craniomaxillofacial (CMF) fractures in 45 cats presented to a veterinary referral centre between 2012 and 2017. METHODS: Cats with a history of head trauma, one or more CMF fractures and a pretreatment CT scan of the CMF region were included in this study. For the purpose of the study, the CMF skeleton was divided into 15 functional anatomical regions and the fracture sites were allocated to one of these functional regions. Statistical analysis was performed using R. RESULTS: Skull fractures were evident in 80.0% of cats, and mandibular fractures in 86.7% of cats in this study. The median number of anatomical functional regions affected was eight and there was evidence of moderate or strong correlation between fractures of different regions of the mid-face. Where fractures were recorded in the nasopharynx and orbit they were bilateral in 93.5% and 89.7%, respectively. Twenty-six (57.8%) of the cats had fractures affecting one or both temporomandibular joints, which included fractures of the mandibular fossa, condylar neck and condyle. Twenty-nine cats (64.4%) had tooth fractures and seven cats (15.6%) had significant eye injuries. CONCLUSIONS AND RELEVANCE: Cats presenting with a single symphyseal separation or parasymphyseal fracture are very likely to have further fractures at other locations. Fractures in the nasopharynx, orbit, nose, upper jaw, intermaxillary suture and zygomatic arch regions (the 'mid-face') are likely to occur together. The pattern of distribution of mandibular fractures is not as predictable as that for maxillary fractures. CT imaging is required to achieve a complete diagnosis of the location and distribution of skull fractures in cats after head trauma.

Caudal mandibular fracture repair using three-dimensional printing, presurgical plate contouring and a preformed template to aid anatomical fracture reduction.

CASE SUMMARY: Two cats were presented with mandibular fractures following head trauma. Following a CT scan, both were diagnosed with fractures of the ramus. The CT scans were used to print three-dimensional (3D) models of the mandibular fractures, which were used to pre-contour stainless steel mini-plates. These were fixed to the models and the screw positions used to produce a stainless steel template. The template was used as a pattern during surgery to drill holes in the ramus so that the pre-contoured mini-plates could be fixed in the exact same position as they had been on the 3D model. The fractures healed in both cats achieving normal jaw function and occlusion. RELEVANCE AND NOVEL INFORMATION: Conventional techniques used to treat caudal mandibular fractures in cats, such as maxillomandibular fixation and bignathic encircling and retaining device (BEARD), are associated with significant patient morbidity and postoperative complications. Internal rigid fixation is difficult because of small bone size, requirement for considerable plate contouring and difficulty in achieving accurate anatomical reduction of caudal mandibular fractures. These are the first reported cases of mini-plate fixation of caudal mandibular fractures in cats using 3D models, pre-contouring of bone plates and the use of a template to facilitate accurate plate positioning, which may provide an alternative technique suitable for fixing caudal mandibular fractures in cats.

Three Dimensional Osteometric Analysis of Mandibular Symmetry and Morphological Consistency in Cats.

Objectives: The aim of this study was to describe a number of anatomical reference points which can be used to measure mandibular morphology and assess the degree of mandibular symmetry in a group of normal cats. Comparisons were then made between cats to evaluate correlations between morphological measurements and degree of inter-cat variation. This will provide data valuable evaluating and developing techniques for caudal mandibular fracture repair. Methods: Twenty-seven mixed breed cats (26 Domestic Shorthaired and 1 Domestic Longhaired) with no history of head trauma, intact undamaged mandibles, both mandibular fourth premolars and first molars present which had a full skull CT scan were included in this study. Anatomical reference points were defined on maximum intensity projections of multiplanar reconstruction of the mandibles and measurements taken. The ratios between paired right and left measurements, and the ratio of jaw widths at the coronoid process and mandibular foramen were calculated. All analyses were performed using R version 3.3.3 and the multcomp library. Results: None of the right:left ratios were detected as being significantly different from 1 and the coefficient of variation values were all very small showing that when cats deviate from the mean ratio they do so by only a small amount. Measurements analyzed to determine how consistent individual measurements were between cats showed that the most consistent measurement was the lateral ramus inclination angle. The least consistent measurements were ramus height and jaw width at the mental foramen. The correlation between pairs of measurements of the right and left ramus was analyzed and demonstrated a strong correlation between the height, width and length of the ramus. Conclusions: This study has demonstrated a low level of asymmetry between contralateral mandibles in cats, a high level of consistency in the dimensions of mandibles between cats and a strong correlation between the height, width and length of the ramus.

An investigation into the architecture and composition of a urinary calculus.

A bladder stone of diameter of 16 mm was sectioned to reveal an internal structure showing some complexity. Visually apparent were concentric rings divided into two principal zones. The outer zone comprised large single interlocking crystals, but the inner zones consisted of a much more fragile environment in which large single crystals were embedded in a much finer matrix. More detailed analysis was performed on the stone's layers using X-ray diffraction which is capable of identifying the crystallites but may also be used to elucidate some of the crystallite characteristics and thereby provide evidence for the growth environment. Proton induced X-ray emission was carried out at a number of points along a radius of the sample to examine the distribution of key trace elements. A possible mechanism for the influence of this banding on the fragility of the stone is discussed.