Department of Morphology, Imaging, Orthopedics, Rehabilitation and Nutrition, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium.
Biometrics Research Center, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium.
Anat Histol Embryol. 2022 Sep;51(5):640-657. doi: 10.1111/ahe.12838. Epub 2022 Jul 24.
This study investigated the influence of several covariates on the time and sequence of deciduous dentition emergence in puppies. Data were obtained in a longitudinal study, with some cross-sectional observations, of 1001 puppies of 53 dog breeds. A parametric proportional hazards survival model was used to estimate median emergence time and evaluate the effect of the covariates. No significant differences were found between the left and right sides of a puppy's dentition, but differences were statistically significant for the earlier appearance of maxillary incisors and canines and later appearance of maxillary premolars compared with their mandibular counterparts. The tendency for delayed onset and completion of emergence in female compared to male puppies was statistically but not clinically significant. The differences between puppies of breeds of different size or skull type were both statistically and clinically significant, with small and brachycephalic breeds showing later emergence times, longer clinical eruption times and more individual variation. Per quadrant, regardless of dog breed, canines or incisors were usually the first teeth to emerge and fully erupt, followed by premolars in the order Pd3 > 4 > 2. The maxillary canines and incisors usually emerged earlier than mandibular canines. Age estimation standards for breed size groups are presented based on the number of emerged teeth per quadrant. To assess whether a puppy has reached the legally required minimum age of 8 weeks to leave the litter, the best predictive capability using the data from this study is obtained when assessing the emergence status of the deciduous third premolars.
本研究调查了几个协变量对幼犬乳牙萌出时间和顺序的影响。数据来自对 53 个犬种的 1001 只幼犬进行的纵向研究，其中一些为横断面观察。使用参数比例风险生存模型来估计中位萌出时间，并评估协变量的影响。在幼犬牙齿的左右两侧未发现显著差异，但上颌切牙和犬牙的早期出现以及上颌前磨牙的晚期出现与下颌对应牙相比存在统计学上的显著差异。与雄性幼犬相比，雌性幼犬的萌出起始和完成时间延迟具有统计学意义，但临床意义不大。不同体型或头骨类型的犬种之间的差异在统计学上和临床上均有显著意义，小型犬和短头型犬的萌出时间较晚，临床萌出时间较长，个体差异较大。无论犬种如何，每一角区的犬齿或切牙通常是最早萌出和完全萌出的牙齿，其次是按 Pd3 > 4 > 2 的顺序萌出前磨牙。上颌犬齿和切牙通常比下颌犬齿更早萌出。根据每个象限萌出的牙齿数量，提出了不同品种大小组的年龄估计标准。为了评估幼犬是否达到了离开窝的法定最小 8 周龄要求，使用本研究的数据评估乳牙第三前磨牙的萌出状态，可以获得最佳的预测能力。
