How to Repair Rostral Mandibular and Maxillary Fractures

1. Introduction

Fractures of the rostral mandible, premaxilla, and incisive bones can be repaired with wire or acrylic. Only fractures that can be readily repaired with stainless steel wires are discussed.

Causes

Causes include kicks from other animals, becoming entangled in or running into a fence, and pulling back on stationary objects.¹

Clinical Signs

Clinical signs include anorexia, difficulty prehending feed, quidding, ptyalism, halitosis, swelling, heat, pain, and incisor malalignment. Oral pain is manifested by difficulty or unwillingness to eat.^1–3

Evaluation

Oral examination should be performed and is often the only evaluation necessary. Radiographs may provide additional information. Lateral, dorsoventral, and oblique views should be included. Rostral fractures may be more clearly imaged by intraoral placement of the radiographic cassettes. 

Goals

The goals of treatment are early return to normal mastication, resolution of infection, and adequate cosmesis

2. Equipment

Equipment includes stainless steel wire (16- or 18-gauge), needle holders or pliers, wire cutters, acrylic, and a drill. A spool speculum or section of PVC tubing placed between the cheek teeth improves access to the oral cavity. If the procedure is performed under general anesthesia, it is recommended that a nasotracheal tube is also placed to facilitate breathing.

3. Positioning and Preparation

Simple fractures involving one to five incisors can be repaired in the standing, sedated horse with local anesthesia. Mental and infraorbital nerve blocks provide effective regional anesthesia in these cases. The mental nerve may be blocked at the mental foramen, or the mandibular alveolar nerve may be blocked at the mandibular alveolar foramen. The infraorbital nerve may be blocked as it exits the infraorbital foramen. Alternatively, direct infiltration anesthesia can be used but is not recommended. Fractures involving the interdental space are more commonly repaired under general anesthesia in either lateral or dorsal recumbency, depending on fracture configuration, as the repair methods discussed in this report are not sufficiently stable for this type of fracture. Antibiotics and nonsteroidal anti-inflammatory agents are administered before surgery. Ideally, a nasotracheal tube is placed to protect the airway. The mouth is rinsed with water to remove accumulated feed material, and the area surrounding the fracture site is scrubbed with povidone-iodine soap and rinsed again. If a wire will be passed around the premolars, stab incision sites are clipped and prepared aseptically.
 

Anatomy

The primary structures potentially involved in the repair of these fractures are the premaxilla (incisive bone); incisive part of the mandible; incisors; canine teeth; mental, inferior alveolar, and infraorbital nerves; intermandibular synchondrosis; and permanent tooth roots. The permanent incisors, canines, and premolars are formed from separate enamel organs that are derived from lingual (medial) extensions of the dental laminae of the deciduous teeth.⁴ The permanent incisors erupt on the lingual aspect of the deciduous incisors.

The mental nerve emerges from the mental foramen on the rostrolateral aspect of the horizontal ramus, approximately midway between the second premolar and the third incisor. The inferior alveolar nerve continues rostral to the mental foramen in a smaller canal along with the vasculature of the lower incisors.¹
 

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