@phdthesis{8757313,
  abstract     = {{Alpacas are increasingly popular in Western Europe, not only bringing new challenges to their owners, but also to the local veterinarians. Dental disease is recognized as a frequent condition affecting alpacas (Vicugna pacos), but peer-reviewed research is currently mainly limited to tooth root abscessation. Etiopathogenesis of dental disease in this species is poorly understood and specific risk factors have only been hypothesized without any scientific supportive evidence. No prevalence data on the occurrence of specific dental disorders are currently available. Diagnosis is often only made in a chronic stage of the disease based on the accidental detection of a hard and bony swelling at the level of the mandible. Treatment options are limited and often comprise of exodontia. Advanced dental treatments are not fully developed and habituated in this species given the lack of supportive anatomical information needed for the successful performance of this techniques.
To allow disease prevention and provision of scientifically substantiated devices to owners regarding specific management strategies, there is a great need for objective studies unravelling risk factors associated with specific dental disorders. However, another aspect to prevention holds the early diagnosis of specific dental disorders which is of primary importance to avoid the development of advanced disease processes associated with a guarded prognosis. The best strategy to allow a timely diagnosis of dental disease in alpacas has not been elucidated yet. The study of the general and (pulpar anatomy) of cheek teeth in this species might lead to novel necessary insights into the etiopathogenesis of dental disease. Also, the development of more advanced tooth saving techniques in this species might benefit from these findings given the small amount of cheek teeth elements contributing to the occlusal surface. Therefore, the overall aim of this doctoral thesis was to gain a better understanding of the prevalence, etiopathogenesis and diagnostics of dental disease in alpacas, paving the path for better diagnostic and therapeutic approaches in the future.
In the general introduction (Chapter 1) a literature review on current knowledge regarding dental anatomy and structural characteristics of alpaca teeth is given. Subsequently, scientific literature concerning prevalence, etiopathogenesis and diagnosis of dental disease in this species is summarized. In the final part of the general introduction, treatment strategies applicable for different specific dental disorders are described in detail.
In the first study, the histological appearance of normal, non-diseased alpaca cheek teeth was studied to gain a better understanding of their structure and possible susceptibility to disease (Chapter 3). The histological results of the investigated dental tissues showed great similarities with dental tissues in other hypsodont species. Nevertheless, a rare type of dentin called ‘vasodentin’ could be identified in all studied cheek teeth. Another remarkable finding includes the presence of massive resorptive lesions at the level of neighboring roots in extremely close proximity, originating from adjacent elements. The massive resorptive lesions at a root level have been hypothesized as important factors contributing the development and spread of dental disease in alpacas.
Although histology has led to the discovery of these resorptive lesions at specific locations, the overall frequency of contacting roots still remains to be unraveled. Therefore, a two- part μ-CT study has been conducted focusing on mandibular and maxillary cheek teeth specifically. Distomesial root contacts have been frequently observed between Triadan 09-10s (80%) and 10-11s (67%) at the mandibular level (Chapter 4.1). Physical contacts between the roots of adjacent teeth were also found in most examined molars (range 82-94%) at the level of the maxillary dental arcade (Chapter 4.2). Next to the prevalence of contacting roots, age-dependent characteristics of the conformation of the pulp system were studied. These insights prove to be of primary importance for the development of advanced treatment strategies whereby details of the pulp system appear vital for the acquirement of good results. Also, focus on the subocclusal dentinal thickness on a cheek teeth level showed minimal amounts of secondary dentin being present subocclusally, supporting the current advice of only performing dental floating in case of wear abnormalities. Routine floating of the cheek teeth in this species should be avoided. Further studies of the subocclusal dentinal thickness in teeth suffering from wear abnormalities remain necessary to be able to formulate a definite advice in these specific cases.
The prevalence of specific dental disorders in all types of teeth was unknown at the start of this research project. However, a high prevalence of dental disease was expected based on findings in other herbivorous species. A large field study including over 200 alpacas from Belgium and the Netherlands was conducted to determine the prevalence of specific dental disorders in alpacas by means of oral examination (Chapter 5.1). Furthermore, mutual relationships between these detected abnormalities were studied to gain novel insights into the etiopathogenesis of dental disease in this species. Historically, several risk factors have been hypothesized as contributing factors for the development of apical disease in alpacas. To gain a better understanding and to allow an assessment of the contribution of these risk factors to specific dental disorders, questionnaires were answered by all alpaca owners willing to participate in the field study. Multivariable logistic regression was used to identify risk factors associated with the different dental disorders (Chapter 5.2). Every increase in herd size resulted in increase of the risk for PD with 2% (95% CI, 1-4%). Surprisingly, stocking density did not show the same association. Periodontal disease also showed a significant association with mandibular swelling and BCS. With the latter indicating a painful situation, possibly impairing animal welfare. For each 1-day increase in interval between pasture cleanings, the odds of finding pulp exposure for a single animal was estimated to increase by 1% (95% CI, 0-2%).
Up until now, oral health in alpacas has often been neglected until a stage of severe dental disease whereby a pronounced swelling becomes evident in case of pathology at the level of the lower dental arcade. For the purpose of this study, severe dental disease was defined as any advanced disease process including endodontic disease, apical infection, and/or severe PD. The influence of age, gender and measurement level were studied as factors possibly influencing thickness of the mandible in non-diseased animals. Using this knowledge, a tool for the screening for severe dental disease based on a mandibular thickness measurement was developed whereby a cut-off of 19 mm was found as an indication for severe dental disease (Chapter 6.1). On average, severe dental disease showed to cause an increased mandibular thickness by 1.9 ± SE 0.3 mm (95% CI= 1.29-2.51 mm). Sensitivity and Sp of this technique was 0.41 and 0.92, respectively. This technique shows potential to aid in the earlier detection of animals in need of specialized dental care, but the relatively low Se indicates other screening strategies remain necessary to allow timely detection.
Finally, in Chapter 6.2, the value of the novel designed mandibular thickness measurement tool was evaluated compared to other easily accessible screening tools in the field. Diagnostic accuracy of mandibular thickness measurement (cut off= 19 mm, measured at two levels, based on a line drawn from the mesial aspect of the medial canthus of the eye or from the lateral canthus of the eye, respectively, perpendicular to the longitudinal axis of each mandibular arcade), oral examination (Presence of gingival recession combined with pulp exposure and/or purulent gingival drainage, and/or increased mobility of one or more teeth), and presence of low BCS (BCS £ 1.5) was compared by means of a BLCM to account for the absence of a gold standard. The Bayesian estimate of the prevalence of severe dental disease was 2.6% (95% CrI: 0.9-5.2%). Se and Sp were obtained for mandibular thickness measurement and were 51.4% (95% CrI: 22.5-88.4%) and 88.3% (95% CrI: 85.9-90.5%), respectively. For body condition scoring Se and Sp reached 68.6% (95% CrI: 37.5-97.9%) and 80.8% (95% CrI: 78.0-83.5%), respectively. Se and Sp of oral examination were 79.0% (95% CrI: 60.1-92.0%) and 97.9% (95% CrI: 96.2-99.4%), respectively. The results of this study show increased mandibular thickness and to a lesser extent low BCS, to be very specific for severe dental disease, but generally lack Se in order to reliably detect animals with severe dental disease. The conclusion of this study was that routine oral examinations currently provide the sole means for the screening for severe dental disease at the level of the mandibular arcade in alpacas. Additional advantages include the diagnosis of minor, possibly preceding disorders in an early stage and the possibility to allow an evaluation of the dentition at the level of the maxillary arcade. In the general discussion (Chapter 7), novel insights into the etiopathogenesis and epidemiology of dental disease in alpacas are discussed. Different diagnostic strategies, including serial testing using combinations of 2 of the 3 aforementioned tests, are evaluated using Fagan Nomograms. Low sensitivities were associated with the use of BCS (54.2%) and mandibular thickness measurement (40.6%) as screening tool for the detection of animals which could benefit from an oral examination and subsequent treatment. The use of oral examination as a sole screening tool proves to be superior to any of the combinations, showing a Se of 79.0%. Animals exhibiting any sign of severe dental disease upon oral examination at the level of a specific location are expected to be diseased at that specific level in 67% of cases. Finally, also novel insights into specific treatment strategies are discussed. In this thesis, novel insights into the etiopathogenesis of dental disease in alpacas were acquired. The prevalence of dental disorders in alpacas in Belgium and the Netherlands is very high (Chapter 5.1). Preventive measures on a management level might include the aiming for stress reduction in larger herds and the frequent clearing of feces from the animals’ premises on regular intervals (Chapter 5.2). This thesis provides evidence for the need of oral examination to be performed on a regular basis to allow the early detection of dental disease in alpacas (Chapter 6.2). This should be a major step to allow a timely diagnosis of minor dental abnormalities prior to the development of advanced dental disease and to detect severe dental disease at an early disease stage, allowing a good prognosis by prompt treatment. Novel insights into the general and pulpar anatomy in this species (Chapter 4) might provide a basis for the development of more advanced tooth saving strategies in case of the development of severe dental disease in this species, bringing veterinary dentistry in the alpaca to a next level.}},
  author       = {{Proost, Kirsten}},
  keywords     = {{Alpaca,dental pathology,histology,anatomy,microCT}},
  language     = {{eng}},
  pages        = {{IV, 320}},
  publisher    = {{Ghent University. Faculty of Veterinary Medicine}},
  school       = {{Ghent University}},
  title        = {{Towards a better understanding of dental pathology in domesticated alpacas}},
  year         = {{2022}},
}