How to perform dental extraction in a cat with minimally invasive still efficient techniques. How to avoid complications and how to solve postoperative dysfunctions of the mouth in a cat.
Inflammatory oral diseases in cats are the most important problems in feline dentistry. Controlling inflammation is the key to management of this disease process and so far, the most efficient way to manage it is the surgical treatment.
Extraction of the teeth affected with inflammation from any cause should be performed. However, since the majority of patients have widespread inflammation, the most successful long-term treatment for cats with chronic gingivostomatitis is the complete extraction of all premolars and molars including the periodontal ligament as well as smoothing the alveolar bone. Extraction of the canine and incisor teeth is indicated when the inflammation extends to include the gingiva surrounding them. Full mouth extractions are, therefore, often performed in cases of significant oral inflammation, while some veterinary dentists prefer to leave the canines and incisors if at all possible.
Choosing appropriate hand instruments is critical for achieving successful extractions. It is agreed that the following are always a part of the surgical kit:
- Blade holder #3
- Tissue forceps
- Periosteal elevator
- Tissue scissors
- Suture scissors
The surgical kit for cats should have selection of smaller fine instruments and may be also combined and packed together with diagnostic instruments.
The necessary addition to this kit is an extraction package which contains luxator and elevator assortment as well as extraction forceps and possibly a separate set of instruments dedicated of solving complications: root tip forceps, root tip elevator. For cats normally the small slim and medium variations of luxators and elevators are required.
A part of the extraction kit is also the selection of burs being used while surgical extraction. Most commonly used burs are round burs, pear shaped, fissure burs, in both standard and surgical length.
High speed diamond burs are also extremely useful when performing surgical extractions in cats. One, in particular, is a medium grit, medium sized, football shaped bur that serves to remove alveolar and buccal bone in a much less aggressive fashion compared to the various carbide burs. This is advantageous when one attempts to smooth and re-contour the sharp edges of crestal bone after a tooth has been extracted.
High-speed instrumentation will encompass the high-speed hand pieces that attach to any high-speed dental unit driven by compressed air or nitrogen gas. Such hand pieces operate by driving compressed air through a high-speed turbine.
Both pre-operative and postoperative dental radiographs must be exposed to document complete extraction of all tooth roots. Producing pre-extraction intraoral radiographs will help define the extent of the pathology, and will demonstrate the anatomic variability present with the tooth in question. Intra-operative radiographs may prove to be valuable when the extraction has not proceeded as expected, or if root fractures have occurred.
The first step in surgical extraction is to create an access flap. The first is parallel to the free marginal gingiva, and is produced by inserting the scalpel blade into the gingival sulcus or immediately parallel to it, and extending an incision rostral and caudal to achieve the desired length. A periosteal elevator is used to separate the mucosa and periosteum away from the bone to allow limited access and visualization. This is creation of the full thickness flap.
Once the buccal bone over the root structure has been exposed, a high-speed carbide bur can be used in a gentle stroking motion to remove the crest that exists near the level of the original sulcal or para-sulcal incision. When performing an extraction on a multi-rooted tooth, it is often easiest to remove the crestal bone over the central aspect of the tooth first to obtain visualization of the furcation before extending the bone removal to the distal and mesial aspects of the root structure.
Buccal bone is removed to expose 30–50% of the overall root length. The crown is then sectioned with a carbide bur at the site of the furcation to separate each root for individual extraction. The space created by the bur during the sectioning process provides an initial insertion point for a small dental elevator. Gently twisting the elevator in one direction and then the other will start to stress the periodontal ligament fibers that hold each root within its alveolus.
Placing too much rotational pressure on the elevator at this point will simply fracture the roots. Slow, steady, continuous pressure is the key to breaking down the periodontal ligament fibers. Rapid, forceful, and intermittent pressure will greatly increase the chances of fracturing roots. Once the space at the site of sectioning has widened slightly, the dental elevator can then be inserted along the mesial and distal aspects of the tooth with gentle, apically directed pressure.
The key is to start advancing the cutting edge of the elevator into the periodontal ligament space. If apically directed pressure is placed against the crown of the tooth or against the crestal bone, no progress will be made in elevating the root, and slippage of the elevator may result. Keeping the elevator dry at the sites of hand contact will also help to minimize slippage and undesired patient trauma. As the periodontal ligament fibers start to tear, the roots will start to show small degrees of movement. Placing the dental elevator on the lingual aspect of each sectioned crown and pushing it apically into the periodontal ligament space will help loosen the roots further. As the elevator is gently advanced apically, the mobile roots tend to displace coronally, indicating a successful extraction.
The following step is to perform an osteoplasty with a medium grit, medium sized football shaped diamond bur to reduce the sharp alveolar crest and bony ridges to a smooth surface which will safely accommodate the full thickness flap upon closure. Post-extraction radiographs are made prior to suturing the site.
Extracting canine teeth in the cat can be particularly challenging, given the relatively long roots and delicate surrounding jaw structures. This is especially true for mandibular canines, where symphyseal separations and rostral mandibular fractures can be a complication of the extraction process. Creating a full thickness triangular flap on the buccal aspect of the mandibular canine tooth in combination with a lingual envelope flap can help with the surgical exposure and process of selective bone removal. Using a high-speed carbide bur to remove bone over the buccodistal aspect of the root can be helpful when extracting this tooth. This preserves a mesiobuccal section of bone and can serve as a fulcrum for a dental elevator. Removing bone, in such a fashion as to create a “slot” between the root surface and the remaining alveolar bone, provides an available insertion point which can guide the tip if the elevator to the periodontal ligament space. Slow, sustained pressure used to both twist the elevator and drive it apically is what will work to loosen the root of the canine tooth. Sudden forceful movements will increase the risk of root or jaw fractures. Once a canine tooth has been extracted, the alveolus curetted and flushed, and osteoplasty completed, it is well worth considering a bone augmentation product to fill the alveolus prior to closing the mucoperiosteal flap.
Tension-free suturing and an appropriate shape and size of flap are of key importance. Flaps planned to cover certain areas have to be larger (approximately 50%) than the size of defect due to postoperative shrinkage.
Generally, absorbable monofilaments are recommended for oral surgery, size 5/0 for cats. This type of material causes the least irritation and is associated with the least amount of infection. Poliglecaprone 25 is the most popular material but in wounds where slow healing may be anticipated, PDS may be a good option.
Suture needles for oral surgery must be the swaged-on type. Needle curvature is either 3/8 or 1/2 with the latter more indicated in the caudal part of the oral cavity. A reverse cutting needle is the best for suturing gingiva and mucosa but for delicate mucosa, a taper point may be optimal.
The needle should be inserted into tissues perpendicularly to make the smallest possible entry wound and to avoid tearing of the mucosa.
Double layer suturing in major surgical procedures is better than one layer if possible. A distance of 2–3 mm between the wound edge and the suture entry point and a 2–3 mm distance between interrupted sutures is recommended. In general, a single interrupted suture is best and recommended in most oral procedures, although some authors suggest the use of continuous sutures after total extractions in stomatitis patients reduce the time of closure and decrease surgical time.