Figure - available from: Frontiers in Veterinary Science
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The equine interdental gingiva is cone shaped and has a non-keratinized stratified squamous epithelium with rete pegs (a). In direction of the tooth the epithelium flattens (b) and finally connects to the tooth (c). The lamina propria includes leucocytic infiltrates in a low number spread all over the connective tissue and in high numbers locally near the epithelium (d). C, cementum; JE, junctional epithelium; LP, lamina propria; P, plaque; Co, Col.
Source publication
Equine periodontal disease in horses has long been recognized as a painful disease, leading to a poor condition. The disease is widespread and attracts growing attention in equine dental medicine. The understanding of the underlying etiological and pathological mechanisms of equine periodontal disease is necessary to develop effective prophylactic...
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Citations
... In human and canine dentistry, precise descriptions of morphological and histological features of the gingiva exist (1)(2)(3)(4)(5)(6)(7). In contrast, the gingiva of the horse is addressed only in a few studies (8)(9)(10). The gingiva, along with the cementum, periodontal ligament and alveolar bone, forms the structural and functional group of tissue called the periodontium. ...
... Samples were assessed via light microscopy (Leica DM750, Leica DM2500 and Leica ICC50 HD, Wetzlar, Germany). With slight modifications, the system of Steinfort et al. (8) was used to evaluate the following parameters in the dental and interdental gingiva and the subgingival periodontal tissue: ...
... The predominant presence of a parakeratinized stratified epithelium in the oral gingiva of horses is in line with findings documented for brachydont species like dogs, cats and humans (41)(42)(43). The higher amount of orthokeratinized epithelia in controls might reflect a higher mechanical irritation in these sites (8,44,45). The types of epithelia within the oral gingiva, sulcular epithelium and junctional epithelium were not significantly different between PPID and controls. ...
Introduction
Pituitary pars intermedia dysfunction (PPID) and dental disorders are of major concern in horses older than 15 years. Although PPID in geriatric horses and dental disorders in all age groups are well described, a connection between this endocrine disease and pathological changes in equine dental structures has not yet been investigated. In humans, periodontitis is considered to be a complication of systemic diseases like diabetes mellitus type 2, obesity and various conditions leading to an impaired immune response. In PPID, cross links to insulin and immune dysregulations are proven. The aim of this study was to compare histological findings of the gingiva and the sub gingival periodontal ligament of PPID affected horses with control horses.
Methods
In a case-control morphometric descriptive study, 145 dental locations of 10 PPID affected horses (27.3 ± 2.06 years) were compared with 147 dental locations of 10 controls (21.4 ± 4.12 years). Histological parameters were leukocyte infiltration, keratinization of gingival epithelium, blood vessel supply of the periodontium and structure of cementum.
Results
The distribution and localization of gingival leukocyte infiltrations (LI) in PPID affected horses was more often multifocal to coalescing (p = 0.002) and reached into deeper parts of the periodontium, sometimes down to the sub gingival periodontal ligament (PDL). Aged animals of both groups showed higher prevalence (PPID: OR 1.66; controls: OR 1.15) for severe leukocyte infiltration in the PDL. PPID was not significantly associated with increased LI. The cementum bordering the soft tissue in interdental locations showed four times more irregularities in PPID affected horses than in controls which predisposes for interdental food impaction and periodontal diseases.
Discussion
In summary, multifocal to coalescing leukocytes and irregular cementum are seen more often in PPID than in controls - however our findings mainly reflect an association of older age with periodontal disease.
... Bei älteren Pferden kommt es bei gleichbleibenden und orthogonal auf die Kaufläche der Schneidezähne wirkenden natürlichen Kräften ebenso zu einer Belastungsakkumulation des Parodonts entlang des Alveolarrandes (Schrock et al., 2013a). Die mikromorphologischen Charakteristika des gingivalen Epithels beim Pferd ähneln in diesem Bereich stark jenen brachyodonter Spezies, inklusive des Menschen (Steinfort et al., 2019). Vorerst bleibt unklar, ob sich die Regenerationsfähigkeit des junktionalen gingivalen Epithels beim Pferd, aufgrund der kontinuierlichen Eruption equiner hypsodonter Zähne und der damit verbundenen kontinuierlichen parodontalen Remodellierung (Warhonowicz et al., 2006), von brachyodonten Spezies unterscheidet. ...
In humans, naturally occurring or applied orthodontic forces can cause excessive periodontal stress, which in turn may lead to alveolar bone loss or apposition and root resorption. Equine Odontoclastic Tooth Resorption and Hypercementosis (EOTRH), an incisal periodontopathy in the horse, shows similar alterations. It is well known that the horse´s hypsodont incisors are subjected to continuous morphometric changes and periodontal remodeling processes and that changes in the age-dependent periodontal force distribution follow a spatial pattern similar to the appearance of the first radiological signs in EOTRH. In this regard the age-related variability of interincisal angulation (IIA) is attributed an important pathoetiological role. However, previous studies generalize one angle for all tooth positions. Methodological standards or metric data are largely missing. The aim of this study is to provide an overview of the technical basics and the area of application of a standardized conventional CT examination of the head with multislice detector systems on the standing sedated horse and to give an overview of the radiological appearance of normal oromaxillofacial structures and pathologies, and also to establish a validated CT-based cephalometric approach to determine the age- and tooth position-dependent IIA of clinical crowns. The mini-review article combines empirical values and retrospective data from CT examinations on standing sedated horses exclusively. For the cephalometric measurements of the IIA of clinical crowns, CT-based multiplanar thick-slab reconstructions from individual incisors of 48 horses without incisor changes (2 - 20 years; 8.8 ± 4.6 years) were used, considering a global reference frame. The IIA was defined as the angle between the respective labial axes of opposing incisor clinical crowns. The reconstructions of labial axes followed a standardized protocol based on certain dentoalveolar landmarks. In addition to a measurement repeatability analysis, the newly established method (labial axes) was compared with a cephalometrically implemented reference method, that considers the lingual/ palatal surface of the 03s clinical crowns and is originally based on lateral profile photographs. The permanent incisors were used to determine the age-dependent angular course and potential tooth position-dependent differences.
It has been shown that CT of the head on standing sedated horses is an adequate method for standardized cephalometric measurements. Both the technical setup and the possibility of standardized positioning of the head implement the applicability of CT studies for cephalometric applications even under usual clinical conditions. In this study, for the first time, the angulation of the clinical crowns of opposing incisors could be determined under methodically standardized conditions and separately for all tooth positions. Globally for all incisor positions, the repeatability of the angle measurements was very high when using reconstructions of the labial axes of clinical crowns based on defined dentoalveolar landmarks (mean coefficient of variation = 0.65%; mean SD ± 0.89°). Compared to the IIA measurements of reconstructed labial axes of the 03s, the mean dispersion of repeat measurements for the reference method was on average twice as high, P = 0.017. The observed age-dependent angle decrease follows a nonlinear course, with younger horses showing the greatest decrease and the slope of the curve flattening with increasing age. This indicates that the IIA might approach an end value in older horses (mean coefficient of variation of approximations = 4.8%). Globally, the 03s show the largest decrease, P < 0.0001. The observed age- and tooth position- dependent angle differences are reflected in the appearance of the first signs and in the progressivity pattern of EOTRH. The biomechanical influence of angular alterations should therefore be taken into account for etiopathological considerations of EOTRH. Cephalometric applications based on computed tomographic data are likely to play an increasingly important role in future in equine dentistry and maxillofacial surgery for measurements of interdental or dentofacial angles, dental malocclusions as well as craniofacial asymmetries, and at the same time may contribute to a better understanding of the etiologies of several dental and maxillofacial pathologies.
