Non-invasive oral fracture repair (Proceedings)
Oral fracture repair in dogs and cats has traditionally taken many different forms. Pins, plates, screws and external coaptation devices are all methods previously employed that are relatively invasive. Small dogs and cats and immature animals have very little bone volume to support the more invasive devices often resulting in failure. Noninvasive methods employing the teeth and using interdental wiring, orthodontic devices, composite and acrylic can bypass traditional invasive methods decreasing procedure time and ensuring a comfortable occlusion and rapid return to function.
Oral fractures are particularly painful. Pain management should be an immediate concern for all patients with oral fractures. Immediate assessment of patient status should take into consideration possible complications of administration of certain analgesics. For example patients with concurrent ocular trauma and potential glaucoma should not be given morphine in that associated vomiting from this agent will result in and acute increase intraocular pressure. Opiates should be avoided or used with caution in patients with respiratory compromise due their potential for causing respiratory depression. NSAIDS should not be used in patients with hypovolemia, dehydration or renal compromise. The patient should be considered as a whole when choosing appropriate analgesics.
A minimum data base should include a thorough physical examination, CBC, chemistry profile, electrolytes, blood gas analysis, urinalysis, thoracic and abdominal radiography and an EKG. Total patient analysis is paramount prior to consideration for sedation and oral evaluation.
Following the evaluation of the minimum database disposition is made concerning safety for general anesthesia and gross and radiographic evaluation of the oral cavity. If the minimum data base suggests that anesthesia is contraindicated preparation is made to compensate the patient for critical issues delaying anesthesia until the appropriate time. If definitive treatment must be delayed a tape muzzle should be placed to minimize additional tissue trauma from movement unless respiratory distress or vomiting are more pressing concerns.
The oral examination under anesthesia should include careful intubation not only for inhalant administration but just as importantly for airway protection. Oral hemorrhage and vomiting are common with head trauma and could severely decompensate the patient if an airway is not immediately established upon induction. A careful thorough oral examination should include maxillary and mandibular bone palpation, visual examination for swellings and lacerations in and around the oral cavity and skull, open fractures, epistaxis, TMJ fractures and luxations, symphyseal fractures, tooth fractures, tooth luxations and avulsions, malocclusions and lingual trauma.
Full mouth dental radiography is indicated following a thorough oral evaluation. Detail obtained from dental radiography allows for detection of lesions not possible with conventional skull films. Oblique and VD TMJ films are indicated if assessment indicates possible problems in this area.
Fractures of the mandible are more common and often more challenging than maxillary fractures in both dogs and cats. Displacement may be significant especially if both mandibles are involved. When repairing mandibular fractures primary attention must be paid to occlusion. If the teeth are returned to proper occlusion with non-invasive techniques, fracture repair is simultaneously accomplished. A proper occlusion eliminates tooth on tooth or tooth on tissue trauma postoperatively that might compromise apposition. Occlusion cannon be assessed without extubation and bite evaluation. Therefore it is often helpful to perform a pharyngostomy to reposition the endotracheal tube so that occlusion can be checked during and after repair.
Favorable fractures are mandibular fractures where the normal forces of opening and closing the mouth aid in apposition of the fracture ends. The fracture line in these cases runs from the rostroventral to the caudodorsal mandible. Normal digastricus muscle function pulls the rostral aspect of the mandible caudally when opening the mouth. Similarly the temporalis and masseter muscles act to pull the caudal mandible in a rostral direction when closing the mouth. Therefore the both processes of opening and closing the mouth impose favorable forces to oppose fracture ends in this type of injury. These fractures are often repaired solely with the aid of an acrylic splint applied to the lingual aspect of the teeth as the jaws are brought into occlusion.
Nonfavorable fractures exist when opening and closing of the mouth provides distraction forces to the fracture ends. When a fracture line runs rostrodorsal to caudoventral the muscles of mastication instill an effect opposite that of favorable fractures. These fractures require additional stabilization with interdental wiring and acrylic stabilization. Traditional methods aimed at providing minimal invasiveness include interosseous wiring. This is seldom needed when wiring and acrylic with or without a tape muzzle are employed during healing. Suturing of soft tissue should be delayed until stabilization is achieved in case interosseous wiring is needed. If this is the case access can be achieved in part via the existing defect.
Teeth as Anchors
Teeth within the fracture line should be salvaged if possible. Severe periodontal disease and/or endodontic disease that is preexisting may warrant extraction in come cases. Treatment of these teeth following fracture healing depends on the ability of the dentist to treat the tooth or the bone loss at the time of the fracture. This topic extends well beyond the scope of this manuscript. Veterinary dental texts provide extensive discussions on periodontal and endodontic therapy for teeth in general.1,2 In most cases fracture repair can be completed utilizing the techniques described here. At discharge referral can be scheduled with a veterinary dentist for follow-up care of the teeth involved in the fracture line or otherwise traumatized. It is very important that client communication with this topic is discussed. Pet owners should be notified that traumatized teeth will require follow-up visits with a specialist or qualified individual after discharge from fracture repair. Extraction or endodontic therapy is often indicated especially if the tooth or teeth in question are involved with the fracture line.
Maxillary fractures commonly require little in the form of rigid fixation Soft tissue apposition, tape muzzles and/or acrylic splints are all that is needed in most cases. Epistaxis is a common sequela to maxillary fractures and usually resolves shortly after surgical repair. Ventrodorsal intraoral dental radiography should be employed to check for intranasal bone fragments in cases of severe nasal or maxillary trauma with epistaxis. Removal of fragments will prevent sequestra leading to chronic bacterial rhinitis. This may be accomplished through a displaced palatal fracture site or through dorsal rhinotomy.
Orthodontic massel chain and button configurations have the advantage of providing fixation but eliminating rigidity associated with splints and wires. This may be of special benefit in young patients where jaw growth is not complete to allow some flexibility to further growth. When used alone massel chain and button configurations should be used with tape muzzles and Elizabethan collars to prevent trauma and minimize jaw movement. Orthodontic devices can also be integrated into acrylic splints where additional rigidity is required. Creative application of button and chain configurations may stand alone or form the backbone of acrylic splints providing excellent rigidity eliminating the need for interdental wiring.
Interdental wiring is a viable non-invasive technique that can be used with or without stabilization with acrylic. It involves placement of 24-26 gauge wire between teeth on either side of the fracture line. Wire is generally placed ventral to the cervical bulge at the mesial and distal aspects of the teeth. Anatomical variations may dictate that the wire be passed through the gingiva to establish purchase. Notching of the tooth with a small round carbide dental bur or the utilization of composite bonding to secure the wire to the tooth are also possible. Wiring techniques are described extensively in veterinary dental texts.1,2 The Stout multiple loop technique provides incorporation of two or more teeth on either side of the fracture line. The Ivy loop technique is similar but incorporates only one tooth on either side of the fracture line. For mandibular fractures the loops are tied on the lingual aspect to eliminate problems with occlusion from the maxillary teeth and to act to reinforce purchase of the acrylic. More extensive fractures may require additional techniques. The Risdon's wiring technique may be used in these instances.1,2
Acrylics and Composites
Acrylic splints provide a stand alone stabilization technique for many cases of mandibular and maxillary fracture repair. Unfortunately bonding acrylic to teeth is a technique sensitive procedure. At no time can plaque or saliva contact the surface of the prepared tooth or the procedure may fail. lnterdental wiring is used in many cases to provide stabilization and ensure incorporation of the splint into something other than the tooth surface A unique alternative to increase bonding success involves the use of composite acrylic buttons as an anchor. A composite orthodontic button and bracket system is used to accomplish this. A silicone mold on the end of a plastic wand is filled with a flowable composite to accomplish a slight positive meniscus. The mold is placed on a prepared area of the tooth and light cured to achieve bonding. The mold is pulled from the tooth and the button or bracket is left strongly adhered to the tooth surface providing a solid anchor for retention of the acrylic splint. One bracket or button is placed on each tooth to be incorporated in the acrylic. The following series of steps are utilized to manufacture a acrylic splint using this technique.
1. Thoroughly clean teeth. If interdental wiring is to be used as an adjunct to acrylic splint stabilization rather than composite buttons the wire should be placed after cleaning.
2. Flour pumiceb should be used to thoroughly polish teeth and wire to remove plaque. Any plaque will retard the ability of the acrylic to adhere to the tooth. Flouride containing pastes will interfere with material setup.
3. Acid etch all tooth and wire surfaces that will come in contact with the acrylic for 30 seconds. The labial surface of the mandibular teeth and the vestibular (buccal) surface of the maxillary teeth are used to avoid occlusion issues. Thoroughly rinse the etchant and dry with an oil free air source.
4. Place a small amount of primer/bonding agent on the tooth surface where buttons are to be placed following manufacturers directions specifically. Bonding agents vary considerably in details of placement.
5. Place flowable composite into the mold, hold the mold against the tooth, light cure for the recommended time period and pull the mold from the tooth. The author uses an accelerated light cured composite that cures in 5 seconds. As an alternative, fabrication of an anchor can be done without the mold system by adding sequential layers of composite to approximate a similar contour.
6. After the composite buttons have been placed the acrylic splint is applied using a chemical cure self mix acrylic. Cover the proper aspect of the tooth surface for the length of the splint being careful not to involve the gingiva. Ensure a proper occlusion and apposition of fracture ends as the acrylic dries. This is facilitated by preplacement of the endotracheal tube in the esophagostomy site.
7. Rough areas can be smoothed with Goldie g or other burs. Oral hygiene should be encouraged if possible to keep the splint free from food and debris. The device should be inspected at regular intervals to ensure that it is intact.. Radiographs are taken at 6 weeks to ensure adequate callous formation. The device is removed and the teeth cleaned and polished.
Tape muzzles can also be stand alone treatments for cases of maxillary or mandibular fracture where minimal displacement is present. It may also be used as a salvage procedure to encourage fibrous union in cases where repair is not economically feasible or prognosis for bony union is guarded. This is the case in many bilateral pathologic mandibular fractures secondary to periodontal disease. Tape muzzles are widely utilized and their application described in numerous texts and therefore is not described here.
Classic invasive oral fracture repair techniques have led to inadvertent or careless impingement on oral structures including teeth, periodontal ligament, cementum and the mandibular canal and its contents. Young are particularly terrible candidates for plates, pins, screws and osseous wiring due to the lack of mandibular bone while teeth are maturing. Cats and small dogs also lack significant bone volume. Avoidance of these invasive techniques should be considered paramount in dogs and cats of all ages. Noninvasive techniques are available to provide excellent stabilization, maximizing patient comfort and minimizing complications. They should be strongly considered as techniques of choice in any mandibular or maxillary fracture in dogs and cats.
a. Orthodontic Mold System, Fairfield Orthodontics, (800-321-0331)
b. Flour Pumice Henry Schein, Melville, NY, (800-872-4346)
c. Acid Etch Henry Schein, Melville, NY (800-872-4346)
d. Bond 1 – 5th Generation, Pentron Technologies, Wallingford, CT, (800-551-0283)
e. Flow-it ALC, Pentron Technologies, Wallingford, CT, (800-551-0283)
f. f Maxitemp HP (900-1279), Henry Schein, Melville, NY (800-872-4346)
g. Goldie Bur (252-6531), Webster, Sterling, MA (800-225-7911)
1. Holmstrom SE, Frost P, Eisner ER: Veterinary Dental Techniques. Philadelphia, W.B. Saunders, 1998; 457-480.
2. Wiggs RB, Lobprise HB Veterinary Dentistry – Principles and Practice, Philadelphia, Lippincott-Raven, 1997, 267-274