Malocclusion in rabbits refers to a misaligned or a wrong relation of the directly opposite teeth between the upper and lower dental arches when the jaws are at a resting position. This can be caused by a congenital, genetic or it can be acquired over a long time.
Understanding the rabbit's dental anatomy is key in comprehending and managing the misalignment problem in these animals. Treatments for this and other rabbit problems should be done by a vet. Also, ensure proper bunny teeth care.
To begin with, since the rabbit’s teeth grow continuously, they need to have the correct occlusion so that they are worn out while eating fibrous foods such as grass hay and some leafy vegetations due to their activities with the opposite teeth as well as the abrasive forces by silicate deposits (phytoliths) in these foods.
However, in case of any kind of malocclusion that involves incisors, or cheek teeth, the normal wear during chewing and grinding will cease to occur and overgrown teeth will be the next problem.
Finally, this condition is life-threatening and need to be treated since it will affect eating and food mastication. This will consequently cause GI stasis if your bunny cannot eat or worse, cause dysbiosis, gas, and diarrhea if they decide to prefer soft foods, especially carbs.
There are many causes both congenital as well as those acquired over time. Some of the general causes include the following:
This is an inherited disorder that could result in the incongruity of the maxilla and mandible leading to an overbite or underbite and it can be due to prognathism (longer mandibles relative to the maxilla) or brachygnathism (maxilla is short relative to the mandible).
When due to the skeletal problem, it will be noticed early while your rabbit is still young, usually less than a year. Brachygnathism is often noted in dwarf rabbit breeds including Netherland dwarfs and Dwarf lops.
An imbalance in calcium, phosphorous and vitamin D could also contribute not only to malocclusions but also to other bone-related diseases. This is often considered as a metabolic disease.
Providing this animal with diets that are low in fiber will not only encourage overgrown teeth but also raise chances of wrong dental occlusion if their teeth get very long. This is because they can easily fracture or lead to loss of the opposing incisor in case of trauma.
Always ensure your rabbit has an unlimited supply of grassy hay brands such as Small Pet Select 2nd Cutting "Perfect Blend" Timothy Hay Pet Food, Kaytee Timothy Hay, Oxbow Timothy Hay, Standlee Premium Western Forage Timothy Grass, Vitakraft Timothy Hay, Premium Sweet Grass Hay, among many others.
Trauma and injuries
Any trauma and injuries on these pets teeth including fractures, them biting cage wires, pins, clips, and so on especially by kits while their teeth are growing can make them misaligned among others.
The correct incisor settings in rabbits are such that when their jaws are at rest, the lower incisors should rest behind the upper incisors, i.e., “ the mandibular incisors are situated behind the first larger set of maxillary incisors in occlusion with the peg teeth.” Some of the common causes of incisor malocclusion include the following:
Maxillary brachygnathism is characterized by shorter upper jaws relative to the lower ones. This affects the correct occlusion and incisor attrition that wears them down as this pet is feeding.
Therefore, the upper incisors will elongate and curve inwards while the lower ones will also become longer and protrude outwards onto the nose area.
It is common to note some people calling it mandible prognathism (a bunny having a long lower jaw). However, in most cases, it is the upper one that is short especially in dwarf breeds including the Netherland dwarf and Dwarf lop whereas the lower one is the normal length.
Elongation of cheek teeth and rabbit teeth spurs
Bunnies, especially the older ones may also suffer from this condition due to elongated cheek teeth. This could be due to a number of reasons, especially those related to diets that are low in fiber and lower bone density that comes with aging.
When they elongate, the incisor bite will not cause the expected incisor wearing. This will potentially cause malocclusion.
Elongation is common on the inner edges of lower cheek teeth and outer edges for the case of the upper ones.
Also, the reverse may occur where malocclusion of incisors causes the molar and premolar elongation and consequently result in malocclusion.
Teeth entrapment by a cage, falling, injuries while clipping them (iatrogenic injuries) other trauma may fracture the incisors. The fractured incisor may die or grow in the wrong direction affecting the normal its occlusion with the opposite incisor and hence it will be elongated.
Fractures may also result in other problems including periapical diseases, pupal necrosis or they may stop to erupt and grow.
Poorly formed incisors
Whereas this pet might have an overbite or an underbite, it is possible for their teeth to form poorly making the upper and lower teeth not to meet correctly.
Also, some bunnies showing “cheek-tooth malocclusion at a young age may be victims of genetics affecting the angle of cheek-tooth growth.” 
There will be little or no clinical signs at the initial stages. However, once the condition becomes severe, some of these symptoms may include:
- Injury and damage on soft tissues including gums that may be swollen or have lesions.
- Reduced appetite due to difficulties in chewing and the pet not opening their mouth well. Also, there might be a preference for soft foods.
- Weight loss (common if your bunny does not eat or drink water)
- Signs of pain including a hunched posture, lethargy, hiding, depression, and staying in one place for a long time.
- Excessive drooling characterized by saliva on the chin area, on front paws or near lips as well as matted fur on these areas. A wet dewlap for those that have it may also be noticed. This might cause moist dermatitis and potential fur loss.
- Tongue and cheek injury in the case of elongated premolars and molars (dental spurs).
- Eye discharge if the roots of the maxillary teeth press against the tear duct
- Tooth abscesses
- Chin and jaw area discharge
- Uneven and visibly elongated incisors
- Perforation of the palatal shelf if maxilla incisors eruption “is hindered by abnormal occlusal forces, the teeth will grow in an apical direction.” 
- Inability to groom which may lead to a poor coat. Also, this pet may be unable to eat cecotrophs leading to a sticky bottom and an increase in the risk of flystrike.
Diagnosis is by firstly looking at some of the clinical signs including visible elongated teeth, endoscopic observation to see the presence of minor lesions on the soft tissues caused by premolar and molar spur as well as radiography including X-rays to assess the extent of damage caused.
Your vet may also consider other diagnostic checks if he or she suspects secondary infections or abscesses. This might include blood tests, CT scans and so on.
Treatment should never be ignored since “if left untreated, trauma to the lip, palate, and other maxillofacial structures may occur.”  Treatment will involve teeth trimming, reshaping, removal or the use of digital pressure to realign the affected teeth.
Treatment should be done under anesthesia and analgesia (pain-relieving medication) to reduce the pain that may cause stress to these animals.
Rabbit teeth trimming
Rabbit teeth trimming may often be used, and this should be done periodically after about one to two months depending on the rate of teeth growth (often after 4-6 weeks).
You can “safely and effectively managed by trimming the teeth using either a thin cutting bur such as a tapered coarse grit diamond bur or a thin crosscut fissure tungsten carbide bur.”  The cutting efficiency will be better if a high-speed air turbine handpiece is used. It can be done under anesthesia or not.
Secondly, you can use a canine nail clipper to cut elongated ones. This should be done under anesthesia and it presents several risks including injury to oral cavity tissues, fractures, splitting and so that may predispose these animals to tooth abscesses and infection. We strongly advise against teeth clipping.
There are other ways that can be used to correct or deal with malocclusion down beside clipping and dental bur use. The method your vet will choose will depend on the extent of elongation among other factors.
Digital pressure for one hour daily can help realign the affected teeth. However, realignment may not be possible in some cases.
Tooth extraction can also be considered since trimming is not only expensive but also very inconveniencing. Both the incisors as well as the premolars and molars can be extracted if there is severe damage already.
In case of infections including tooth abscesses, antibiotics or surgical removal, wound flushing, among other ways may be opted for.
Since a wrong diet can contribute to teeth elongation that may consequently promote malocclusion. Ensure you provide diets rich in fiber such as grassy hay as well as some leafy greens.
However, during treatment, you may consider forced feeding if your rabbit does not eat to avoid GI stasis and other digestive related conditions. Try Oxbow Critical Care for Herbivores or EmAraid Herbivore during forced feeding (syringe feeding).
Also, ensure you provide all required nutrients in their right proportions, especially vitamin D as well as calcium.
Sometimes, incisor and molar malocclusion can occur alongside other diseases and conditions including periodontal and endodontic disease. Also, dental osteomyelitis (bone infection) may occur if some of the causes and diseases remain untreated for a long time.
Do not forget to carefully select your rabbit and avoid those genetically predisposed to this problem. A reputed breeder will be of much help.