Editing Researchlinks
From Bun Club Wiki
Jump to navigationJump to search
Warning: You are not logged in. Your IP address will be publicly visible if you make any edits. If you log in or create an account, your edits will be attributed to your username, along with other benefits.
The edit can be undone. Please check the comparison below to verify that this is what you want to do, and then publish the changes below to finish undoing the edit.
| Latest revision | Your text | ||
| Line 66: | Line 66: | ||
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5606619/ | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5606619/ | ||
Abstract: | |||
In contrast to wild lagomorphs, pet rabbits exhibit a noticeably high frequency of dental problems. Although dietary habits are considered as a major factor contributing to acquired malocclusions, the exact causes and interrelationships are still under debate. In this regard, an important aspect that has not been considered thoroughly to date is the effect of diet-induced phenotypic plasticity in skull morphology. Therefore, we conducted a geometric morphometric analysis on skull radiological images of wild and pet rabbits in order to quantify intraspecific variation in craniomandibular morphology. The statistical analyses reveal a significant morphological differentiation of the craniomandibular system between both groups. Furthermore, the analysis of covariance shows that the force-generating modules (cranium and mandible) vary independently from the force-receiving module (hypselodont teeth) in pet rabbits, which is in contrast to their wild relatives. Our findings suggest that the phenotypic changes in domestic rabbits impact mastication performance and, consequently, oral health. An adequate close-to-nature nutrition throughout the whole life and especially beginning early parallel to weaning (phase of increased phenotypic plasticity) is necessary to ensure a normal strain on the teeth by promoting physiological lateral gliding movements and avoiding direct axial loads. | In contrast to wild lagomorphs, pet rabbits exhibit a noticeably high frequency of dental problems. Although dietary habits are considered as a major factor contributing to acquired malocclusions, the exact causes and interrelationships are still under debate. In this regard, an important aspect that has not been considered thoroughly to date is the effect of diet-induced phenotypic plasticity in skull morphology. Therefore, we conducted a geometric morphometric analysis on skull radiological images of wild and pet rabbits in order to quantify intraspecific variation in craniomandibular morphology. The statistical analyses reveal a significant morphological differentiation of the craniomandibular system between both groups. Furthermore, the analysis of covariance shows that the force-generating modules (cranium and mandible) vary independently from the force-receiving module (hypselodont teeth) in pet rabbits, which is in contrast to their wild relatives. Our findings suggest that the phenotypic changes in domestic rabbits impact mastication performance and, consequently, oral health. An adequate close-to-nature nutrition throughout the whole life and especially beginning early parallel to weaning (phase of increased phenotypic plasticity) is necessary to ensure a normal strain on the teeth by promoting physiological lateral gliding movements and avoiding direct axial loads. | ||
Keywords: masticatory apparatus, axial load, malocclusion, reference lines, Lagomorpha, evolutionary morphology, phenotypic plasticity | Keywords: masticatory apparatus, axial load, malocclusion, reference lines, Lagomorpha, evolutionary morphology, phenotypic plasticity | ||
notes: | notes: | ||
"Free living rabbits also strip bark off trees with their incisors and chew it just as they ribble at delicate roots. In addition to that, animals with a healthy dentition grind their incisors and cheek teeth periodically which is called “thegosis” or “bruxism”. These planning jaw movements occur in the absence of food and help to maintain a physiological length and shape of the teeth. Thegosis is seen predominantly when rabbits are at rest [62]. Rabbits with a malocclusion, however, often avoid these special jaw movements due to dental pain. Elongated clinical crowns of both the incisors and cheek teeth are a consequence of this." | |||
"In summary, this suggests that in grazing wild rabbits cheek teeth are strained primarily in a laterorostral direction while shear forces on the interlocked enamel crests dominate and there is only a small amount of axial load on the cheek teeth. In this context, it is reasonable that the first mandibular cheek tooth is the largest of the rabbit dentition. Thus, the teeth lying behind it can firmly prop up against this stronger premolar. In contrast to wild animals, most pet and breeding rabbits predominantly crush “unnatural” food between their teeth (pellets, carrots and other root vegetables) which is accompanied with a much higher axial strain on the (pre-)molars and an insufficient tooth wear (higher clinical crowns) combined with a tendency to retrograde tooth elongation [1]. This fact appears also to explain why longitudinal splits of the first mandibular premolar (P3) are so common in pet rabbits. They are assumed to be the consequence of a load-related apical irritation that results in an abnormal tooth tissue formation (hypoplasia). Thus, the altered cement fails to connect both tooth bodies firmly together (bilophodont cheek teeth) resulting in a longitudinally “split” tooth [1]. | "In summary, this suggests that in grazing wild rabbits cheek teeth are strained primarily in a laterorostral direction while shear forces on the interlocked enamel crests dominate and there is only a small amount of axial load on the cheek teeth. In this context, it is reasonable that the first mandibular cheek tooth is the largest of the rabbit dentition. Thus, the teeth lying behind it can firmly prop up against this stronger premolar. In contrast to wild animals, most pet and breeding rabbits predominantly crush “unnatural” food between their teeth (pellets, carrots and other root vegetables) which is accompanied with a much higher axial strain on the (pre-)molars and an insufficient tooth wear (higher clinical crowns) combined with a tendency to retrograde tooth elongation [1]. This fact appears also to explain why longitudinal splits of the first mandibular premolar (P3) are so common in pet rabbits. They are assumed to be the consequence of a load-related apical irritation that results in an abnormal tooth tissue formation (hypoplasia). Thus, the altered cement fails to connect both tooth bodies firmly together (bilophodont cheek teeth) resulting in a longitudinally “split” tooth [1]. | ||
| Line 83: | Line 83: | ||
" Hay seems to be the most mechanically challenging food as it is tougher and stiffer than pellets ......... [70]. It requires more chews per gram to be processed which results in longer chewing bouts compared to pellets and carrots. This means that over a longer period of time the teeth are predominantly axially loaded due to the elevated bite force. If we take into consideration that hay with a lot of hard stems has reduced nutritive properties and potential limits on digestibility, then rabbits eating predominantly hay need to consume large quantities to meet basic metabolic and nutritional demands [70]. All of this promotes retrograde tooth elongation and incursion of the apices into the adjacent bone (most common finding in malocclusions) [1]. Furthermore, hay also promotes periodontal diseases (impacted food) and, therefore is not the best nutrition for rabbits [31]. Grasses and other fresh plants, however, are abrasive, but relatively soft and, thus, can be ground down with relatively low axial load of the cheek teeth as the primary strain on the (pre-) molars occurs in a more physiological laterorostral direction with the aid of the shearing power stroke""" | " Hay seems to be the most mechanically challenging food as it is tougher and stiffer than pellets ......... [70]. It requires more chews per gram to be processed which results in longer chewing bouts compared to pellets and carrots. This means that over a longer period of time the teeth are predominantly axially loaded due to the elevated bite force. If we take into consideration that hay with a lot of hard stems has reduced nutritive properties and potential limits on digestibility, then rabbits eating predominantly hay need to consume large quantities to meet basic metabolic and nutritional demands [70]. All of this promotes retrograde tooth elongation and incursion of the apices into the adjacent bone (most common finding in malocclusions) [1]. Furthermore, hay also promotes periodontal diseases (impacted food) and, therefore is not the best nutrition for rabbits [31]. Grasses and other fresh plants, however, are abrasive, but relatively soft and, thus, can be ground down with relatively low axial load of the cheek teeth as the primary strain on the (pre-) molars occurs in a more physiological laterorostral direction with the aid of the shearing power stroke""" | ||
===2016 Evolutionary morphology of the rabbit skull=== | ===2016 Evolutionary morphology of the rabbit skull=== | ||
