Current concepts in veterinary dentistry (Proceedings)

The field of veterinary dentistry has truly risen from the dark ages. Companion animals are no longer subjected to mistruths such as: "broken teeth are not a problem" or "supragingival scaling represents a complete prophylaxis." As veterinary dentistry moves through the 1990's into the 21st century significant improvements will be made in the understanding of inflammation at the molecular level and appropriate treatments will emerge. Also, as interest in the feline oral cavity sky rockets its only a matter of time until the odontoclastic resorption complex is understood with resulting effective interventions. Its an exciting time for veterinary dentistry.

Equipment And Materials

The good news is that dental instrumentation is affordable and "do able." The old belt driven dental engines are in museums and air driven high speed equipment is the standard.

The veterinary dental market is being flooded with good equipment. The first entry into the market on a large scale is the Schein "Vet Base" put together by Jerry Morris Associates. These units are every bit as good today as they were 10 years ago. Other features such as fiber optics, suction, additional light sources, light cure guns, and multiple air lines have been added by most manufactures to their units. All dental equipment suppliers share one common problem—providing quiet compressors that delivers sufficient air to drive the hand pieces. Most compressors are converted refrigerator motors that deliver 2.5 cfm. The minimum required is 3.0 cfm thus most compressors are under powered. This results in continuous operation with the tendency for overheating. Some of the newer compressors, such as the IM3 "Hurricane", Vet Base "Silent Surge", and Matrix Oil Less have less of a tendency to overheat. However, maintenance is a must with all compressors and if not performed on a regular basis dental operations will soon come to an abrupt stop. Despite these few short comings "high speed" equipment is the best choice for companion animal dentistry.

Other options for power equipment include the electric micromotor. This is a slow speed device that can be used for dental prophylaxis and endodontics. The major deficiency of micromotors is the heat generated by the working surface of the operative instrument such as a dental bur. This heat is damaging to vital tissue and if the micromotor is used incorrectly iatrogenic problems occur. Micromotors are a good choice for veterinary dental practices limiting their operative procedures to dental prophylaxis and nonsurgical extractions.

Hand instrumentation for periodontal therapy is as important as high speed equipment. The basic includes 1) scalers, 2) curettes, 3) periosteal elevators, and 4) #15 surgery blades. The best scaler for veterinary dentistry is the universal scaler. This scaler has a three sided blade that allows both a push and pull stroke. The working tip also has a point that allows scaling of fissures. As a rule, curettes are numbered according to the location of use on the arcade—the higher the number the further back in the mouth the instrument is used. The author prefers the Columbia #13/14 curette. Periosteal elevators are essential in gingival surgery. The least damaging to soft tissue is the Molt #9 periosteal elevator. This instrument allows the veterinary dentist to reflect attached gingiva, especially in felines, without shredding the tissue. Care should be taken to preserve the sharpness of the working surface. Dull instruments are worthless and create more problems than they solve. Because most of these instruments are inexpensive, if one doesn't feel right during use it can be easily replaced by another of a different design.

Prophy angles, pastes and cups again are a matter of personal preference. As a rule the screw type prophy angles are easier to clean and the autoclavable type more durable. Pastes can range from a slurry of fine pumice (inexpensive) to prepackaged individual containers (the authors preference). The ribbed hard rubber type prophy angle tends to last longer and do a better job than the soft rubber type. For the person who prefers disposable units to help prevent cross contamination, single use prophy angles are available. Unfortunately it usually takes several angles to complete the prophylaxis in the canine patient (some of the products are a bit wimpy because of the plastic gears and drive shafts).

Ultrasonic scalers remain a popular device to help in the removal of gross calculus from crown surfaces. The down side still remain with heat generation and microetching as the problems. Most commercial units have more than enough power to quickly remove gross calculus. However, in the unskilled hand damage to the crown surface and the subgingival area is a real problem. Air driven sonic scalers (especially the Titan S) are being favored because of the non heat generation at their working tip and tendency for minimal damage to the tooth surface. Air sonic scales are used on the high speed air line already in place on the dental unit. Pieseo electric scalers are the next generation of electric sonic scalers. The advantage to these units is the elliptical pattern of the working tip which is reported to minimize hard tissue damage. Because the units operate at a much higher frequency (45k cps) the efficiency of calculus removal is much greater. In addition, units such as the Neosonic by Amadent have endodontic attachments that greatly shorten the operative time of endodontic procedures. The variety of working tips allows the veterinary dentist to complete many different procedures that otherwise would have taken extraordinary amounts of time to finish. As with all power equipment proper use is the corner stone for effective therapy. Iatrogenic damage is a huge concern for the untrained operator.

The next level in instrumentation is dental radiology. As in other veterinary disciplines accurate visualization of internal pathology is mandatory. The good news is that dental x-ray machines are inexpensive (compared to 50ma machines) and provides as much information for pennies. Used dental machines range from $800 to $1000 and new machines from $2500 to $3000. The author suggests purchasing a new machine to take advantage of the legislated safety regulations and manufacturers warranty. The dental films can be developed in existing darkrooms, some automatic processors and in chair side developers. Most veterinary dentists prefer chair side developers because of the convenience and cost effectiveness. The two dental film most commonly used are the periapical and occlusal. Ultra speed film is compatible with chair side developers and is the speed used. The technique is written on the box although some trial and error is used to fine tune the technique. With the advent of digital radiology the ability to diagnosis disease has now markedly improved. There are many systems available – the author prefers the Scan X system because of the availability of size 4 films.

The materials used in veterinary dentistry that is the most confusing and difficult to keep up with is the area of restoratives. For decades dental amalgams and alloys were used to repair teeth and few real improvements were made in these materials. However, in the last twenty years polymers have exploded onto the scene gradually displacing "metal" as the material of choice in crown repair. The biggest frustration is that the technology improves daily and what is being recommended today will be changed tomorrow. Given this fact the current recommendation is made: for restorations a "light cure" composite is preferred. The composite should be used with at least a third generation dentin bonding system to assure adhesion to the tooth surface. The composite should be easy to manipulate allowing creation of smooth margins, elimination of air voids, and complete finishing. Most manufacturers have switched to hybrid fillers so particle size in the resin is becoming less of an issue. More of an issue is the strength and durability of the composite. Kerr's Optibond System is the authors current bonding system of choice and Cosmodents Renamel hybrid is the composite of choice.

Other restoratives that have use in veterinary dentistry include the combination glass ionomer composite materials such as Geristore by DenMat. These products attempt to combine the best characteristics of both materials. The composite resin is used for strength and the glass ionomer is used for adhesion. Because the best characteristics of both materials are compromised when combined the use of this compound should be limited to nonocclusal surfaces. An excellent area is Class V lesions in felines (for those lesions that are suitable for repair) or subgingival fractures lines in both canines and felines. This material is technique sensitive and the best type to use is the light cure.

It is beyond the scope of this paper to discuss all current materials available for restorations. Every veterinary dentist will have a material they feel is superior. The best recommendation is to find a product that is readily available with the fewest steps and follow the manufacturers directions. Most failures occur due to operator error, not material error.

Regardless of the type of composite used a light cure system is the system of choice. The clear advantage is the flexible working time and reduced setting time. The differences between the various manufacturers light cure guns are minimal thus price and ease of repair becomes the chief concern. The author has found little clinical difference between the most expensive and least expensive light cure gun.

Other equipment worth mentioning that should be included in the basic operatory are sharpening stones (the Premier Disc is a good one), gloves (Schein's Biogel Dedicated gloves are excellent), magnifying loops (Aseptico's are inexpensive), and anesthesia (isoflurane is the agent of choice).

Anatomy, Embryonic and Adult

Developmental Defects

The development of the dentition is a continuum from the time the toothbud form until the time the animal dies. The important point to remember is that the toothbud forms in layers, the enamel layer first. This layer is derived from embryonic epithelium in a sac like structure. The next layer is dentin which is derived from embryonic mesoderm. Dentin first forms under the enamel layer and ultimately diverges extending beyond the enamel layer to form the root structure. The continual formation of root dentin is the eruptive force propelling the tooth into the mouth. Eruption stops when dentin root walls close to form the root apex. When tooth impaction occurs alveoloplasty will work only if the root structure is immature. If the apex has closed the only option for impacted (and embedded) teeth are extraction or orthodontic extrusion therapy. The former is the treatment of choice.

Any febrile disease will cause enamel hypoplasia or dysplasia. Unfortunately these conditions are not detectable in non erupted teeth. After eruption affected teeth are at risk of secondary endodontic disease and subsequent tooth loss. Third generation bonding systems will effectively deal with this problem.

Perhaps the condition veterinarians have the greatest impact on is retained deciduous teeth. In principle no two teeth can occupy the same alveolus at the same time. The deciduous tooth is always in correct occlusion therefore the permanent tooth is always in malocclusion. In large breed dogs this is usually not a problem at first because of sufficient space in the dental arcade. However, retained teeth need to be removed to prevent malformation of the periodontium of the corresponding permanent teeth. In small breed dogs retained deciduous teeth is of critical importance. The longer the retained tooth remains in the arcade the more devastating the effects. The best recommendation, especially in small breed dogs, is to extract the retained deciduous tooth at the first hint of retention. If not intercepted, severe malocclusions most always occur.

The adult teeth in dogs and cats are similar but not exactly the same. The enamel layer in cats is less hard than that of dogs and humans. Dentin in both dogs and cats is less calcified than enamel, is formed by odontoblasts throughout the animals life, and can repair itself. Most important is that dentin is porous and has extensions of the odontoblast layer that end near the tooth's exterior. Particular to cats is the presence of vasodentin—small islands of dentin with vascular channels.

The periodontal space contains:

o collagen fibers

o blood vessels

o lymphatic vessels

o neural tissue

The collagen protein plays a critical role in the pathophysiology of periodontitis. The various cells found in the periodontal space include:

o fibroblasts

o osteoblasts

o cementoblasts

o cementoclasts

o rest cells of malassez

o progenitor cells

Covering the root structure is cementum. Cementum is an avascular bone-like tissue. It is acellular at the gingival margin and cellular in the apical region. Most important is that cementum is thin in the furcation area, especially in cats. Healthy cementum is essential to provide an attachment surface for periodontal fibers.

The pulp is the vital nutrient tissue on the inside of the tooth. It provides nutrition to odontoblasts that form new dentin and to dentin through the dentinal tubules.

Of particular importance is the root apex. In puppies and kittens the deciduous tooth has an open apex. In the mature adult tooth the apex is closed. This fact makes endodontic therapy much easier in veterinary dentistry than human dentistry in adult animals.

The problems encountered in puppies and kittens include prognathism or brachygnathism. Prognathism is the clinical condition of an abnormally long mandible whereas brachygnathism is the clinical condition of an abnormally short mandible. Since these may represent developmental problems interceptive orthodontics is indicated. In brachygnathism the deciduous mandibular canines and incisors are extracted to allow the mandible to develop uninhindered. In prognathism the maxillary central and middle incisors are extracted to allow for a more rostral eruption path of the adult maxillary incisors.

Wry mouth is the asymmetrical growth of the mandible or maxilla. Radiographs of the affected arch will define the maldeveloping area. As a general rule the problem is an uneven development of the premaxilla bones. Therapy is centered on relieving the malocclusion usually by extracting the maloccluding teeth.

Canine mesioversion (rostralversion) of the maxilla is an inherited defect with a low penetrance. The Sheltie breed is notorious for producing dogs with this defect. Extraction of the maxillary deciduous canine teeth has minimal interceptive value. Extraction or othodontic correction of the mesioverted tooth is the therapy of choice.

Dilaceration of crowns and/or roots occurs as a developmental defect. Minimally affected teeth may be salvaged with composite bonding of crowns but usually the tooth is too involved and extraction is the treatment of choice.

Anodontia is the congenital absence of some or all of the teeth. This is important in pure bred working dogs such as Dobermans and German Shepherds. Missing adult teeth can be identified radiographically in 12 week old puppies giving a "window into the future". Polydontia is the presence of "extra" teeth. This is only a problem when overcrowding causes malocclusion or areas for food entrapment. Extraction of the extra teeth is the best option.

Other tooth structure defects are as varied as can be imagined. Teeth can be rotated 180 degrees, inverted, averted, and converted. Anomalies are dealt with on an individual basis with creation of a healthy mouth (not perfect) as the goal.

Occlusion problems are dealt with as early as possible on an individual basis. Lingualversion of the mandibular canine teeth has also been dubbed "base narrow" and is the inward rotation of the crowns toward the hard palate. This can be dealt with in the immature mouth if simple lateral movement of the crowns is needed. A temporary bite plate is made for the hard palate using occlusal pressure to move the mandibular canines labially. If the mandibular canines require either rostral or distal plus lateral movement it is best to wait until the animal has finished growing before starting therapy. Anterior crossbites involve the incisors and posterior crossbites involve the premolars and molars. Both conditions are dealt with in the adult animal and orthodontics maybe considered in nongenetic and non inherited cases.

Periodontology

Clearly the number one disease in the oral cavity is periodontitis. The implications of long range systemic effects is becoming clearer with ongoing research. It is a disease that must be dealt with in an effective manner.

Dental terminology, or "Buzz Words" is important. The terms most often used are:

• enamel bulge: that portion of enamel protruding from the crown adjacent to the gingival margin.

• gingival margin: that portion of free gingiva that is most coronal.

• free gingiva: that gingiva that lays against the crown—usually 1 to 3 mm in depth.

• epithelial attachment: the portion of attached gingiva that adheres directly to the tooth surface normally at the level of the CEJ.

• attached gingiva: that portion of the oral tissue that firmly adheres to bone adjacent to teeth.

• mucogingival junction: that line that demarcates attached gingiva from oral mucosa.

• oral mucosa: that epithelial tissue that makes up the labial and buccal surfaces.

• periodontal ligament: dense fibrous material arising from the alveolar bone attaching to tooth root cementum

• furcation: the area under a crown between tooth roots on a multirooted tooth.

• C.E.J.: cemental enamel junction-that point where cementum meets enamel; a landmark for measurement.

Under normal circumstances the attached gingiva and gingival margins are smooth and glistening. The gingival margin has a knife-like edge laying flush against the enamel surface of the tooth. Oral secretions are limited to salivary fluids and there is little if any odor. Facial hair is clean and lip margins are intact. Any disruption of this description is considered disease.

By definition gingivitis is an inflammation of the marginal gingival tissues induced by bacterial tissues induced by bacterial plaque and not affecting the periodontal ligament or alveolar bone. Gingivitis is usually reversible when appropriate prophylaxis and home care measures are instituted.

Periodontitis is a destructive inflammatory process of the peridontium driven by bacterial plaque containing specific bacterial species that cause destruction of the gingiva, periodontal ligament, alveolar bone and root cementum. In animals periodontitis is considered a progressive disease with intermittent active episodes. In man gingivitis and periodontitis may be two separate diseases. As periodontitis progresses the attachment mechanism is lost allowing deep tissue invasion of microorganisms into the supporting structures resulting in periodontal ligament and alveolar bone loss. In the final stages the tooth becomes mobile and is lost.

Of clinical significance is the type of bone loss occurring adjacent to the tooth root. Horizontal bone loss is characterized by simple resorption of bone parallel to the cej's involving adjacent teeth and remaining crestal bone supporting normal periodontium. Vertical bone loss is characterized by maintenance of crestal bone height with loss of periodontal ligament and supporting structure adjacent to the tooth root. Horizontal bone loss usually has minimal "pocket formation" whereas vertical bone loss has huge "pockets" requiring surgical intervention.

There are several established facts about periodontal microbiology. They are:

• periodontal disease is caused by bacteria

• pockets cannot form in the absence of bacteria

• some of the pathogens have been identified; they are mostly gram negative anaerobic motile rods.

• the pathogens probably cause the disease.

The bacteria involved in periodontitis include:

• Porphyromonas gingivalis

• Prevotella species

• Fusobacterium species

• Bacteroides species

• spirochetes

• Actinobacilus-actinomycetecomitans.

On a percentage basis the number of aerobic bacteria decrease and anaerobic bacteria increase as the disease progresses. When evaluating the microbiology in a diseased mouth anaerobic cultures are indicated since aerobic cultures tend to be nonproductive.

Periodontitis can be characterized by the cardinal sign of destruction of the alveolar bone. The features include conversion of junctional epithelium to pocket epithelium, and destruction of the connective tissue matrix of gingiva and periodontal ligament.

Histologically periodontitis is characterized by several stages and closely resembles a typical humoral immune response.

Initial lesion:

• chronic vasculitis

• excudation and invasion of neutrophils

• junctional epithelial alterations

• loss of perivascular structure (collagen)

Early lesion:

• persistence of acute inflammation

• predominance of lymphocytes

• proliferation of junctional epithelium

• loss of perivascular collagen

Established lesion:

• persistence of acute inflammation

• predominance of plasma cells

• proliferation and migration of junctional epithelium

• loss of collagen

• presence of extra vascular immunioglobulins

Advanced lesion:

• predominance of plasma cells

• continued loss of collagen and fibrous connective tissue.

• pathologic alteration of plasma cells

• loss of epithelial attachment

• increased vascular supply.

Most veterinary dentists refer to a staging system when characterizing an animals mouth. Because periodontitis is usually progressive, staging allows for improved record keeping and treatment planning. None of the stages are totally unique and therefore a great deal of variation can occur in an animals mouth. The author uses a six stage system for adult periodontitis. The American Veterinary Dental College recognizes a four Stage system borrowed from the human filed.

The authors Stage 1 is gingivitis. Stage 2 is chronic gingivitis that does not progress to periodontitis. Stage 3 through 6 is periodontitis characterized by attachment loss from minimal (3) to maximum (6) and tooth loss. Obviously stage 5 and 6 animals will require aggressive "rocket science" therapy to maintain teeth while stage 3 mouth will require standard periodontal therapies.

Stage 1: acute gingivitis

• no attachment loss

• limited to the gingival margin

• neutrophil response.

Stage 2: chronic gingivitis (greater than 6 mos)

• no attachment loss

• ± stomatitis, buccal ulcers

• lymphocytes/plasma cells predominate

Stage 3: early periodontitis

• attachment loss

• bone loss`(1-3mm)

• no furcation involvement

• lymphocytes/plasma cells present

Stage 4: established periodontitis

• attachment loss

• bone loss greater than 3mm

• beginning furcation involvement (class 1 & 11)

• lymphocytes, plasma cells predominate

Stage 5: advanced periodontitis

• attachment loss

• less than ⅓ root structure healthy

• furcation involvement complete (class 111)

• plasma cells predominate

• mobility (grade 1 & 2)

Stage 6: end stage periodontitis

• attachment loss

• bone loss to apex

• plasma cell predominate

• apical abscess present

• combined perio/endo lesions

• mobility (grade 3)

Periodontitis can be localized or generalized. When generalized the staging system is an average of the teeth involved i.e. stage 5 or a range i.e. 3/5. When localized the specific teeth are mentioned i.e. #108 stage 5, # 208 stage 3. Regardless, record keeping of disease is becoming the standard and if not done voluntarily the judicial system will dictate it.

The corner stone of adult periodontitis therapy is the dental prophylaxis. The essence of therapy is to control the subgingival infection via debridement of the root surface with or without flaps and with or without antibiotics and to control plaque and reinfection. By definition a dental prophylaxis is the use of appropriate procedures and/or techniques to prevent dental and oral disease and malformations. The procedure includes:

• supra and subgingival scaling

• open/closed subgingival curettage

• open/closed root planing

• crown/root polishing

• fluoride treatment

• charting

Treatment planning for adult periodontitis is based on the stage of the disease. For generalized periodontitis the following treatment plans are suggested as guidelines for therapy.

Stage 1:

• dental prophylaxis

• home care

o Glyoxide

o CET toothpaste

o Maxiguard

o T/D diet

• recall—6 mos to 12 mos as needed

Stage 2:

• dental prophylaxis

• home care

o Chlorhexidine patches, rinses or gel pulse therapy

o antibiotics—pulse therapy for life?

• recall—every 6 mos

Stage 3:

• dental prophylaxis with emphasis on subgingival cleaning; closed curettage and root

• planning

• home care

o short term antibiotics

o short term chlorhexidine patches, rinses or gel

o long term glyoxide or CET toothpaste

• recall—every 6 mos

Stage 4:

• pretreatment antibiotics ?

• dental prophylaxis with emphasis on subgingival cleaning

• open curettage/root planing (flaps)

• home care

o short term antibiotics

o short term chlorhexidine patches, rinses or gel

o long term glyoxide or CET toothpaste

• recall every 3 to 6 mos

Stage 5:

• pretreatment with antibiotics

• initial dental prophylaxis

• open curettage/root planing (flaps)

• extraction (hopeless teeth)

• periodontal splinting mobile teeth

• home care

o antibiotics

o twice a day oral hygiene

■ *AM-glyoxide

■ *PM-chlorhexidine

• recall 2 to 4 weeks

o follow up prophylaxis

o repositioning flaps

o guided tissue regeneration

• recall every 3 mos until stable then 6mos for life

Stage 6: Heroic therapy

• pretreatment with antibiotics

• initial dental prophylaxis

• open curettage/root planing

• periodontal splinting

• extraction's

• home care (for life)

o antibiotics

o twice a day oral hygiene

■ *AM glyoxide

■ *PM chlorhexidine

• recall 2 weeks

o endodontic therapy

o guided tissue regeneration

o repositioning flaps

• recall every 8 weeks until controlled

• recall every 12 to 24 weeks for life.

Obviously, the success of any treatment plan is based on the cooperation of the owner, animal and veterinary dental team. Any breakdown in this equation spells failure.

Recently a bacterin has been released to aid in the control of periodontal disease. The product is a novel approach and represents an effort to control a disease that is progressive and ultimately results in tooth loss. The research model is based on an endodontic model rather than a periodontal models making predictions of success somewhat equivocal. Hopefully the product will help without adding further compromise to the patients immune system. Time will tell.

Once the procedure for each visit is complete, accurate charting of the animals mouth is imperative. Without accurate record keeping success or failure of treatment will be impossible to determine. The Triadan Number System is computer compatible and is suggested as the system of choice. Individual charts are based on personal preference. Small Animal Dentistry by Harvey and Emily has several excellent dental charts for inspection.

Gingival Surgery and Surgical Dental Prophylaxis

Gingivectomies are performed when there is an excessive amount of gingiva, such as gingival hyperplasia, or early pocket formation in areas of plentiful gingiva. However, as a general rule, gingivectomies are not performed when preservation of attached gingiva is the goal.

The therapy of choice for stage 4 through 6 periodontitis is surgical exposure by creation of flaps. Especially when vertical bone loss is present, flaps allow for visualization of diseased tissue. Alveoloplasty, osteoplasty, and root planing allow the animals body the best chance for return to health.

In principle, releasing incisions are made in healthy gingiva diverging from the diseased area from the gingival margin to and sometimes through the mucogingival line. Generally the incision is made over a healthy tooth root and not in the dental papilla. A surgical blade cuts through the free gingival margin directed to the crestal bone peak. The idea is to preserve the height of the free gingiva while surgically removing the pocket epithelium. The remaining healthy attached gingiva is reflected from the bone by using a molt elevator. After appropriate dental therapies are completed flap closure is accomplished by using a simple interrupted inverted suture on the incision margin and circumferential sling sutures through the free gingiva and around the tooth crown. Once the tooth is properly treated, flap healing is remarkably fast.

Oral Nasal Fistula Formation

Periodontitis of the maxillary canine teeth in small dolicephalic breeds such as Dachshunds, often results in severe bone loss on the palatal surface of these teeth. The buccal plate generally holds the teeth in place and is lost only in the last stages of the disease. The result is a communication between the oral cavity and the nasal passageway. Nasal bleeding is pathognomonic for fistula formation during root planing procedures Unless heroic measures for tooth preservation are taken, extraction of the tooth and closure of the fistula is the treatment of choice. The double flap technique described by Emily is the surgical procedure of choice for closure.

Maxillary Sinusitis

Maxillary sinusitis usually results from periodontic or endodontic disease of the maxillary 4th premolar or 1st molar. In brachycephalic breed the maxillary 3rd premolar can also be the cause of it if it is trapped in the furcation of the mesial roots of the 4th premolar. Treatment consists of endodontic and/or periodontic therapy of the causative teeth. However, the permanent "fix" is extraction of the causative tooth.

Exodontia

Perhaps the best procedure for the majority of problems presented to the veterinary dentist is extraction. Clearly there are a multitude of procedures available to preserve teeth, but patient and owner selection are paramount for success. Dental extraction's solve disease problems and should be considered when the goal is to create a healthy mouth. After all, tooth loss is the end result of periodontal disease.

The principles of extraction include:

• the top ⅓ of the alveolar bone surrounding the tooth has ⅔ of the holding power

• periodontal fibers are not designed to withstand slow continuous torque

• multirooted teeth are transformed into single rooted teeth

• preservation of gingiva

• complete extraction of root confirmed by x-ray

• closure of alveolus.

The technique includes non surgical and surgical extraction's. Non surgical extraction's are those accomplished with simple elevation and traction. Theses are usually stage 5 and 6 periodontally involved teeth. Instrumentation is limited to simple extraction forceps, fingers, or needle holders.

Surgical extraction requires:

• flap creation

• removal of crestal bone (osteoplasty)

• isolation of roots (sectioning)

• elevation of roots

• x-ray

• alveoloplasty (if needed)

• closure

The skill required is precision burring with high speed dental equipment. Once the veterinary dentist gains the skills, extraction's become quick and minimally painful for the animal. If pain is anticipated, regional blocks are used such as maxillary and mandibular nerve blocks. In addition butorphenol at 1 mg/ 10 lbs bid to tid for 2 to 3 days is effective to maintain a happy animal. The author has experienced far more success in healing mouths with proper extractions than heroic measures including guided tissue regeneration with osseous induction and periodontal regeneration.

Clinical Orthodontics

Growth and development of the oral cavity does not just happen. There are a series of events that must occur in proper sequence or long term complications will occur. Understanding basic growth patterns in the oral cavity will help the veterinarian to know when to intervene to prevent further developmental defects. The term used is "interceptive orthodontics". Preventing major problems with early intervention is in the animals best interest.

Developmental defects can be divided into three major staging periods. Each stage has its own set of problems thus requiring close inspection by the veterinarian. Stage One is from zero to sixteen weeks of age, Stage Two is from sixteen weeks to seven months of age, and Stage Three is from seven months to one and a half years of age.

Stage One:

Both the feline and canine species are born with "overshot" maxilla's (brachygnathism). This configuration allows the neonatal animals to nurse. As the animal grows and the impending transition from the mother's milk to solid food occurs, the mandible goes through a growth spurt nearly catching up to its relative adult percentage of jaw length. If this spurt does not occur and the deciduous dentition erupts the mandibular canines will most likely be distal (behind) to the maxillary canines. This immediately creates a malocclusion with the potential for inhibiting any chance for the mandible to catch up and seek its proper length. If this occlusal pattern is noticed in a puppy or kitten the best therapy is to remove the mandibular canine teeth (cautiously so as not to damage the permanent tooth bud). If the mandibular incisors are excessive in length and occluded behind the dental papilla the mandibular incisors are extracted using the same care. As a result, the mandible will have the opportunity to catch up to its genetic potential thus averting problems with the permanent dentition. If the animal is genetically predetermined to have a significant overbite this therapy will not affect the outcome.

The other defect to watch for is an "underbite" (prognathism). This occurs when the mandible grows ahead of schedule and becomes too long for the maxilla. This condition becomes evident as early as eight weeks of age. Its is characterized by the maxillary incisors occluding inside the mandibular incisors and the mandibular canines occluding up to or even mesial to the maxillary lateral incisors. The treatment of choice is to extract (with care) the maxillary central and middle incisors. As a rule the maxillary lateral incisors are preserved, especially if the are acting as a deterrent to growth to the mandible. The prognosis for the permanent dentition to be within normal limits is not as favorable as for brachygnathism. However, early intervention is the best hope for the animal.

Other congenital and developmental problems that require intervention include polydontia (extract the extra teeth) or gross displacement of a deciduous tooth (extract the tooth if it is causing mechanical interference). Asymmetry of maxilla and or mandibular growth is dealt with by extracting the teeth on the affected (under developed) side. Asymmetry problems usually carry a poor prognosis for correction but is dealt with to give the animal every opportunity for "self correction."

Stage Two:

The hallmark of problems in this stage is the retention of deciduous teeth. The normal shedding process begins around fourteen weeks of age with the loss of the maxillary central incisors. Then for the next three months the deciduous teeth are replaced with permanent teeth plus additional permanents to complete the animals dentition. If the deciduous teeth are not lost at the time of eruption of the counterpart permanent tooth a malocclusion occurs. No two teeth can occupy the same alveolus at the same time so by definition the permanent tooth is always in malocclusion. Obviously the treatment of choice is to extract the deciduous tooth the minute retention becomes evident. Only in rare circumstances will an error be made by removing a deciduous tooth. The phrase "when in doubt whip it out" is a good rule of thumb.

Other developmental defects that occur in this stage include lingualversion of the mandibular canine teeth, rostralversion of the maxillary canines, and brachygnathism. When the canine teeth have finished erupting a window of opportunity exists for simple orthodontic correction of lingual displacement of the mandibular canine teeth with a maxillary bite plate. Because the oral skeletal system is developing at a rapid rate at six to seven months of age orthodontic appliances can only be left in an animals mouth for two to three weeks at a time. Thus, any therapy must be accomplished in this short period of time. Rostralversion of the maxillary canines typically occurs in the Sheltie breed of dogs, although it has been reported in many small breeds as well as cats. If orthodontics is to be attempted it is best to wait for the animal to finish growing for as long as possible. The distal dentition does not mature until at least ten months of age so this is the minimum age for the beginning of orthodontic therapy. If attempted,

buttons brackets and masial chain are the materials of choice. And finally, brachygnathism is dealt with using temporary maxillary bite plates if the degree of brachygnathism is minimal. If the brachygnathism is severe (mandibular canine occluding on the palatal side of the maxillary canine) other options are considered such as crown reduction of the mandibular canines or extraction of the maxillary canines.

Stage Three

The final stage of developmental occlusal defects occurs from seven months to eighteen months of age. Anterior crossbites (incisors in reverse scissors) and posterior crossbites (carnassial teeth in reverse position), crowding, tooth rotation along with the final expressions of prognathism and brachygnathism are evident. Anterior crossbites can be dealt with if the remaining dentition is within normal limits (most anterior crossbites are a result of prognathism) using maxillary expansion screw splints or other accepted orthodontic treatments. Posterior crossbites are best dealt with by extracting the maxillary fourth premolar. If othodontic treatment is attempted a very cooperative animal and owner are mandatory. Crowding of teeth (large teeth-small space) is resolved by extracting the offending teeth. Likewise, teeth that are rotated greater than forty five degrees (often found in brachycephalic breeds) are removed from the animal. If there is any doubt as to which teeth to remove remember the phrase "establish normal anatomy" and few errors will be made.

In conclusion, orthodontic problems can be dealt with at a practical level by extracting unhealthy teeth. While many malocclusions are not unhealthy (i.e. simple anterior crossbites) thus being more of a concern for a "show dog" many unhealthy malocclusions can be solved with a set of elevators and high speed burs (rostralversion maxillary canines). In the final analysis, interceptive orthodontics is the best recommendation following the old adage that "an ounce of prevention is worth a pound of cure." For those animals with correctable defects orthodontics is an option for many companion animal owners.