The Influence of Force Direction on the Fracture Pattern and Fracture Resistance of Canine Teeth in Dogs

Abstract

Biomechanical studies of the elongated canine tooth of animals are few, and thus our understanding of mechanical and physical properties of animal teeth is limited. The objective of the present study was to evaluate the influence of force direction on fracture resistance and fracture pattern of canine teeth in an ex vivo dog cadaver model. Forty-five extracted canine teeth from laboratory beagle dogs were standardized by hard tissue volume and randomly distributed among 3 force direction groups. The teeth were secured within a universal testing machine and a load was applied at different directions based on testing group. The maximum force to fracture and the fracture pattern classification were recorded for each tooth. After correcting for hard tissue cross-sectional area in a multivariate analysis, no significant difference in the amount of force required for fracture was apparent between the different force direction groups. However, the influence of force direction on fracture pattern was significant. The results of this study may allow the clinician to educate clients on possible causal force directions in clinically fractured teeth and, thus, help prevent any contributing behavior in the future.

Effect of Alternative Palatal Root Access Technique on Fracture Resistance of Root Canal Treated Maxillary Fourth Premolar Teeth in Dogs

“…However, previous studies have found no detectable effect of freezing, or storage temperature in general, on the behavior of human periodontal ligaments or fracture resistance when tooth strength is evaluated by a force displacement curve (32,33). Furthermore, the storage and harvesting methods used in this study were consistent with previously reported methods in canines (22,26,27). Based on this information, the authors believe it was unlikely that storage conditions had a significant effect on the results of the present study, as all teeth were stored and tested in the same manner.…”

“…For reference, the difference between the crown height to diameter ratio in the Soltero-Rivera Paper (23) was 2.38 standard deviation lower than our mean, and so we would predict an average difference of 33 N (95%CI: −288, 221) in force to fracture between the two study cohorts based on differences in crown height to diameter ratio alone. Thus, our study is not in conflict with the findings of numerous other biomechanical studies (23,26,27) that found there is a trend for decreased fracture resistance as the height to diameter ratio increased. Overall, the authors believe the lack of identified statistical significance was primarily due to the minimal variation in crown height to diameter ratio in the cohort, as was intentional in the study design, rather than the height to diameter ratio not being a significant contributor to overall fracture resistance in endodontically treated maxillary fourth premolar teeth.…”

“…Conversely, direct comparison of fracture resistance between structurally sound teeth in the previous study and endodontically treated teeth in the current study is difficult due to the inability to control for many important variables between study populations including crown height to diameter ratio, hard tissue volume, age, breed, weight, and dental history. Notably, there was a slightly higher average crown height to diameter ratio within this study population compared to the Soltero-Rivera study (23) (0.69 compared to 0.60), which may have directly contributed to the decreased fracture resistance, as this is a known confounder of tooth strength in dogs (23,26,27).…”

Taking a stab at modelling canine tooth biomechanics in mammalian carnivores with beam theory and finite-element analysis

“…This type of work has been undertaken on domestic dog ( Canis familiarus ) canines, with patterns observed that support some of the above predictions [ 28 , 81 ]. For example, a trend toward lower force to fracture (N) when teeth are loaded in the lingual–labial direction [ 81 ], in addition to transverse fracture being one of the most common fracture types under lingual–labial loading [ 81 ]. Future research should expand on these studies by including a broader range of canine forms.…”

“…However, this requires further study and validation through closer inspection of specimens with broken teeth to identify the type and location of breakage, in addition to in vivo breakage testing of real teeth under controlled conditions. This type of work has been undertaken on domestic dog ( Canis familiarus ) canines, with patterns observed that support some of the above predictions [28,81]. For example, a trend toward lower force to fracture (N) when teeth are loaded in the lingual–labial direction [81], in addition to transverse fracture being one of the most common fracture types under lingual–labial loading [81].…”