Orthodontic correction of overjet/overbite ('parrot mouth') in 73 foals (1999-2013).
Authors: Easley J, Dixon P M, Reardon R J M
Journal: Equine veterinary journal
Summary
# Editorial Summary Overjet and overbite (parrot mouth) represent a significant functional and aesthetic concern in young horses, yet evidence supporting specific treatment protocols has historically been sparse. Easley, Dixon and Reardon's retrospective analysis of 73 foals treated over 14 years with tension band orthodontics combined with inclined plane biteplates provides valuable outcome data: 95% achieved some reduction in overjet and 90% in overbite, with mean reductions of 9.9 mm and 8.4 mm respectively, though complete correction occurred in only 25% of the 61 foals with complete records. Critically, age at treatment initiation emerged as a significant predictor of success, with younger foals demonstrating greater total reduction and faster correction rates, suggesting early intervention—before dental maturation—is optimal for this technique. Whilst short-term complications (intraoperative haemorrhage, transient facial nerve involvement) were generally self-limiting, longer-term sequelae including cheek teeth diastema formation and incisor discoloration warrant consideration when counselling owners about realistic outcomes. For practitioners managing malocclusion cases, these findings support early referral for orthodontic assessment, though the reality that functional correction (≤5 mm malposition) rather than complete correction was achieved in just over half the cohort underscores the importance of realistic expectations and potentially combining orthodontics with other management strategies.
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Practical Takeaways
- •Early intervention in foals with overjet/overbite is recommended, as older animals show significantly poorer correction outcomes with this technique
- •Multiple implant placements (median 2, range 1-4) are often necessary for adequate tension band placement
- •While rapid improvement is typical with minimal complications, practitioners should counsel owners on potential long-term sequelae including diastema formation and incisor maleruption
Key Findings
- •Orthodontic tension bands with inclined plane biteplates achieved reduction in overjet and overbite in 95% and 90% of foals respectively, with mean reductions of 9.9 mm and 8.4 mm
- •Complete correction of overjet was achieved in 25% of cases, while functional correction (≤5 mm) was achieved in 51% of cases
- •Increasing foal age at treatment initiation was significantly associated with decreased total reduction in overjet and decreased rate of overbite correction
- •Short-term complications included intraoperative hemorrhage and transient facial nerve neuropraxia; longer-term complications included cheek teeth diastema formation and incisor discoloration