Dentistry in general practice

Question 0

What is dentine?

Answer 0

The main substance of the tooth. it is 70% inorganic in composition. Dentine is covered and protected by the more brittle enamel on the crown and by cementum on the root. Dentine is porous and sensitive. It is tubular in structure containing 40-50,000 tubules per square mm. Each tubule contains an odontoblastic process and sensory nerve. Dentine is not normally exposed, being covered by enamel.

Question 1

What is the crown?

Answer 1

The part of the tooth that is above the gum, the crown consists of one or more cusps. A canine tooth has one cusp, a molar has several.

Question 2

What is primary dentine?

Answer 2

It is present at tooth eruption, secondary dentine is slowly deposited throughout life in response to gradual wear and tear and tertiary or reparative dentine is laid down very quickly in response to trauma. Tertiary dentine tubular structure is less well organised and reflects light differently and its surface is more likely to absorb pigments.

Question 3

What is cementum?

Answer 3

An avascular and bone like mineralised connective tissue which covers the root. Cementum s constantly produced in life.

Question 4

What is enamel?

Answer 4

Enamel is the hardest tissue in the body and is 96% inorganic material. (mainly Ca hydroxyapatite). Enamel thickness is around 0.2 mm in cats and 0.5mm in dogs. Its formation is complete by the time of tooth eruption. It cannot repair itself.

Question 5

What is the Cemento-enamel junction

Answer 5

This is the area of transition between cementum and enamel, at the neck of the tooth. It is also the point where the free gingiva ends and the attached gingiva begins.

Question 6

What is the pulp?

Answer 6

The soft centre of the tooth, containing blood vessels, lymphatics, nerves and various cell types including odontoblasts. Each root has a pulp canal and there is a common pulp chamber in multi rooted teeth. The pulp is open in young animals at the root apex, by one year of age this pulp canal at the apex has reduced to an apical delta of 10-20 small passages that contain vessels and nerves running from the pulp to the surrounding tissues in the periodontal system.

Question 7

What are sharpeys fibres?

Answer 7

Fibres of the periodontal ligament which unite the alveolar bone on one side and the cementum on the other in a meshwork of inter woven branches, looking the tooth in place and also absorbing shock from chewing motions.

Question 8

What is the main arterial & nerve supply of the tooth?

Answer 8

Common carotid artery > external carotid artery > maxillary artery > mandibular artery.

Trigeminal n > maxillary n and mandibular n.

Question 9

Describe the blood supply of the mandibular teeth?

Answer 9

The mandibular artery enters the mandible at the mandibular foramen and becomes the inferior alveolar artery. It runs within the mandibular canal and exits at the mental foraminae where branches are now called the mental arteries.

Question 10

Describe the blood supply of the maxillary teeth?

Answer 10

The maxillary artery and its branches supply these teeth. The main branch running within the infraorbital canal is the infraorbital artery. The infraorbital nerve accompanies it and gives off caudal, middle and rostral superior alveolar branches.

Question 11

Where can nerve blocks be applied?

Answer 11

Local anaesthetic nerve blocks can be applied at the mandibular, mental, and infraorbital foraminae to block the nerves - a simple and useful technique to help achieved balanced anaesthesia during tooth extraction.

Question 12

Why do teeth hurt?

Answer 12

Sensory nerves are present in the dental pulp. They enter the pulp through the root apex along with arterioles venules and lymhatics. Direct pulp damage (thermal, mechanical, inflammatory) causes pain. Exposed dentine is also painfu, possibly due to fluid movements within dentinal tubules which in turn irritate the nerve endings deeper within the pulp tissue. Drying of exposed dentine irritates the odontoblastic processes lying within the dentinal tubules, also causing pain.

Question 13

What is the dental formulae of a dog?

Answer 13

Primary teeth I 3/3 C 1/1 PM 3/3 M 0/0 - 28 teeth in total

Permanent teeth - I 3/3 C 1/1 PM 4/4 M 2/3 - 42 teeth in total

Question 14

What is the dental formulae of a cat?

Answer 14

Primary teeth - I 3/3 C 1/1 PM 3/2 M 0/0 - 26 teeth

Permanent teeth - I 3/3 C 1/1 PM 3/2 M 1/1 - 30 teeth in total

Question 15

When should teeth erupt in puppies and kittens?

Answer 15

Deciduous teeth - There are no teeth at birth. Canines - through by 4 weeks. Incisors, premolars - through by 5-6 weeks. All primary teeth are usually present and correct by 6 weeks in both kittens and puppies. Remember no deciduous molars. Permanent teeth - Incisors, canines - usually coming through at 3 months. Premolars - usually coming through at 4 months. Molars usually coming through at 5 months.

Question 16

What elements SHOULD be present in normal tooth occlusion?

Answer 16

Scissor bite of incisors - upper incisors sit slightly rostral to lower. The lower incisors engage with the cingulum of the upper incisors. Lower canine rostral to upper - evenly occupying the space betwen the upper canine and the 3rd upper incisor. Premolars and molars inter digitates in a pinking shear fashion. Upper carnassial lingual aspect engages with lower molar buccal aspect.

Question 17

What is malocclusion?

Answer 17

Anything not conforming to the normal tooth occlusion. Causes of occlusion 1) skeletal malocclusion - i.e pertaining to jaw bone length or width. Usually considered inherited. b) dental malocclusion - the tooth positioning within the jaws. Other than certain breedes, usually considered acquired. So both genetic and environmental/developmental factors can be involved in malocclusions.

Question 18

Why are not all puppies or kittens in a litter affected by malocclusion?

Answer 18

The inherited aspect is probably via a polygenic mechanism, which explains why not all are affected.

Question 19

What is an undershot jaw?

Answer 19

Mandible longer than it should be. Also called mandibular prognathism. Mandibular canine not sitting evenly in the space between upper 3rd incisor and maxillary canine. Loss of premolar pinking shear, loss of incisor scissor bite. Upper incisors may be caudal to lowers.

Question 20

What is an overshot jaw?

Answer 20

Mandible is shorter than it should be. Also called mandibular brachygnathism. typical features include upper incisors too rostral to lower incisors such that they may not engage with each other. Mandibular canine has too much space in front of it and touches the maxillary canine or is even behind it in severe cases.

Question 21

What is a wry bite?

Answer 21

Lop sided growhth of head producing a crooked bite and a twisted face. Narrow mandible common. Mandible width too small in relation to maxilla. Bottom canines grow into hard palate in position medial to up upper canines. Quiet puppy, head shy, picky appetite and poor growth. The malocclusion can produce a dental interlock which prevnts normal growth of the mandible resulting in ventral bowing of the mandible as the continuing growth has to go somewhere.

Question 22

What are persistent primary teeth?

Answer 22

Mainly the canines and incisors. Commoner in small breeds where it seems to have a familial inheritance pattern. Retained teeth interfere with the eruption path of the permanent teeth and can cause dental crouding. There should never be a corresponding deciduous and permanent tooth of the same type in the same place.

Question 23

Describe the basic mechanisms of periodontal disease?

Answer 23

Supra-gingival and sub gingival plaque accumulates > bacteria colonise, initial bacteria are aerobes and facultative anaeerobes. as condition progresses oxygen levels in gingival sulcus reduce > anaerobes take over, periodontal pockets form due to tissue destructive actions of bacterial toxic by products.

Question 24

What is plaque?

Answer 24

75% organic including food residues, 25% inorganic component (ca and P mainly) contains glycoproteins and polysaccharides which glue the plaque onto the tooth surface. Mineralised plaque is calculus which is usually seen on the buccal aspect. Thick layers can build up. The main problem of calculus is as a plaque retentive surface.

Question 25

What is the progression from normal to severe periodontitis and tooth loss?

Answer 25

Normal gingiva > plaque > inflamed gingival margin (gingivitis) > fluid (neutrophil rich) accumulates in gingival sulcus > bacteria colonise > cellular infiltrate develops > junctional epithelium swells and breaks down, deepening sulcus > tissue destruction at periodontal ligament and alveolar bone crest begins > pocket deepens and widens > debris accumulates in pocket. > bone resorption progresses > tooth becomes progressively more mobile > tooth eventually lost.

Question 26

What is the grading of periodontal disaese?

Answer 26

Stage 0 - normal, stage 1 - gingivitis, stage 2, early periodontal disease, stage 3 - moderate periodontal disease, stage 4 - severe periodontal disease.

Question 27

What are the possible results of periodontal probing?

Answer 27

Supra bony pocket: involves the soft tissue only
Infra bony pocket: the pocket extends into the alveolar crest bone which is destroyed.
Pseudopcoket : caused by hyperplastic gingiva which migrates towards the crown and so the sulcus depth appears deeper than normal.
Receded gums and horizontal bone loss: the gingiva recedes and bone crest also recedes so pocket depth appears normal but the root surface can be exposed and periodontal disease can be severe. The gingival sulcus of dogs should be no more than 4mm deep. In cats it should be no more than 1mm deep and is usually 0.5mm. More than this > periodontal disease.

Question 28

How is the degree of gingival recession measured?

Answer 28

It can be measured in mm from the cemento enamel junction to the free margin. Recession can hide deep attachment loss because the proving depth remains within normal limits despite progressing disease.

Question 29

What is the degree of furcation exposure?

Answer 29

Graded 0 (none) to 3 - (the periodontal probe can be passed through the furcation of the tooth from buccal to lingual). This measures the amount of horizontal bone loss.

Question 30

How is the degree of tooth mobility measured?

Answer 30

Graded 0 (none) to 3 (more than 1mm of movement and vertical as well as horizontal movement possible)

Question 31

What are dental caries?

Answer 31

Caries most often affects the first molar of the canine lower jaw. The disease is an acid induced loss of tooth mineralisation. The acid being produced by bacteria acting on food residues. The enamel and dentine are demineralised and a pit or cavity is formed in the tooths occlusal surface. When this pit is touched using a dental explorer a dragging sensation is felt due to the softened dentine present. Treatment can involve restoration of the tooth after removal of diseased enamel or detine, or extraction when there has been too much loss of tooth structure.

Question 32

What is an ultrasonic scaler?

Answer 32

Scalers remove dental deposits from the teeth. Although gross deposits are removed by hand using extraction or calculus forceps followed by hand scaler instruments, powered scalers are more efficient. Ultrasonic scalers have a handpiece with a vibrating tip which is driven by a piezoelectric mechanism. the tip vibrates in a longitudnal directiono

Question 33

Name one disadvantage of an ultrasonic scaleer

Answer 33

They generate heat when held firmly against the teeth for to long. This can traumatise the pulp cavity of the tooth, cause post o pain and perhaps lead to pulp cavity necrosis. Scalers should never be used without water flow. Standardd tips should not be inserted under the gum line for more than one second as they cannot be cooled effectively here. Special tips with built in irrigation are available for safe sub gingival scaling eg cavitron FSI inserts.

Question 34

What is a sonic scaler?

Answer 34

This type of scaler is driven by compressed air from a compressed air driven dental unit. Sonic scalers vibrate slower, produce less heat and are safer, but less efficient.

Question 35

What is a polishing unit?

Answer 35

Must polish teeth as the micro irregularities on the teeth caused by scaling will rapidly re accumulate plaque and calculus. A polishing cup is used together with fine grade prophy paste in the slow speed handpiece of the air driven dental unit. Paste is added to the polishing cup or smeared onto the teeth and the surfaces are then polished, for only a few seconds at a time.

Question 36

What is a compressed air driven dental unit?

Answer 36

The dental machine. Air dental units greatly facilitate dental surgery. They must have a compressed air to drive the handpieces. This comes from an electrical compressor or an air cylinder. A high speed handpiece with water cooling used for cutting bone and teeth. A slow speed hand piece used for polishing teeth, slow speed cutting and other functions. A three way air/water syringe - to wash the mouth and dry the tooth surfaces. Suction. Power is controlled by foot pedal and removal of a hand piece from its yoke directs the air supply to that attachmnt.

Question 37

What are burs?

Answer 37

Fot cutting and sculpting bone and teeth - are secured to the handpieces by friction grip mechanism on the high speed handpiece or latch mechanism on the low speed handpiece. Only a few round or taper cut fissure burs are needed for general veterinary dentistry: friction grip sizes 1,2 and 4 in round burs and sizes 700L and 701L in taper fissure burs cover nearly all needs for extracting teeth.

Question 38

What is dental film?

Answer 38

Non screen, intra oral film. Sizes 2 and 4 are most used in vet dentistry. The X ray images on dental film give very good dental. the film is usually conveniently processed in a small chair side developer.

Question 39

What is a luxator?

Answer 39

Used to break down the periodontal ligament prior to extraction. The periodontal ligament retains the tooth in its alveolus. This intruments thin end allows it to be introduced into the periodontal space around the tooth. This causes haemorrhage which aids in the loosening of the tooth. Various sizes are used according to the patient.

Question 40

What is an elevator?

Answer 40

Used to elevate the tooth from its socket. this instrument is stouter than the luxators and is used mainly with rotational leverage to move the tooth and loosen it. If an attempt is made to apply first oder leverage the tooth may fracture, complicating the process considerably.

Question 41

What are scalpels used for in dentistry?

Answer 41

To delineate and incise muco periostal flaps for surgical extractions and to make the initial gingival incision around the circumference of a tooth to be extracted prior to using luxators and elevators.

Question 42

What is a hand scaler?

Answer 42

These are useful instruments which can be used alongside or before ultrasonic scalers. They are used in a root to crown direction above the gum margin to remove calculus deposits.

Question 43

What is a sub gingival curette?

Answer 43

A scraping instrument designed to be used mainly below the gum margin to remove deposits attached there. It can also be used above the gum margin if desired. It is used with sharp drawing motions in a coronal direction.

Question 44

What is a periodontal probe and explorer?

Answer 44

The explorer is a sharp instrument used to check for the presence of caries and to explore tooth defects. It can be either straight or curved. The probe has a rounded end with graduations etched on the shaft, it is designed to be inserted into the gingival sulcus and gingival pockets in order to measure their depth and so assess the status of teeth.

Question 45

What is a periosteal elevator?

Answer 45

Used to rarise muco periosteal flaps and to free up gingival margins for suturing.

Question 46

What are the indications for tooth extraction?

Answer 46

Loose teeth and those with moderate to severe periodontal disease, persistent deciduous tteeth, teeth affected by caries, feline tooth resorption or other destructive processes, fractured teeth with pulp exposure which are not being treated with endodontics, extra teeth or crowded teeth, teeth involved in a jaw fracture line.

Question 47

How do you extract a tooth with a single root? ( not including canines)

Answer 47

Incisors, some premolars and to multi rooted teeth after they have been sectioned into single rooted fragments with the high speed handpiece and a taper cutting bur. 1. perform scale and polish and flush with 0.12% chlorhexidene. 2. insert a no 15 blade into the gingival sulcus and cut round the tooths epithelial attachment at the base of the sulcus. 3. use a luxator to locate periodontal ligament, rotate it around the tooths long axis to sever the ligament on all sides of the tooth. 4. an elevator can then be used to loosen the tooth as necessory. 5. the loose tooth then removed with fingers or forceps. Flush with chlorhexidine. Suture soft tissues without tension. If too friable best left unsutured. Hold a moistened swab onto extraction site for 1 minute to encourage a clot.

Question 48

How are multi rooted teeth extracted?

Answer 48

Unless very loose or compromised these teeth are best sectioned into single rooted units and then extracted as above. The teeth are sectioned from the furcation point using a taper fissure bur, cutting from the furcation towards the crown. If necessary the gingiva can be elevated in order to locate the furcation. The split tooth sections can then be levered apart using an elevator blade. Apply leverage using the elevator shank and maintain for 15 seconds.

Question 49

How are canines extracted?

Answer 49

Challenging dental surgery because of large teeth, long roots and the problem that the widest part of the tooth is below the margin and opening and exceeds it in diameter. Cut the canines epithelial attachment with a sulcar icision, extend the sulcar incision to create a flap incision from the last incisor to the 1st or 2nd premolar. Raaise the flap with periosteal elevated. The attached gingival is the hardest to move. After this the flap raises easily. Remove bon overlying the canine root with a round bur in high speed dental hand piece. Insert the elevator into the channel around the tooth and rotate it to weaken the periodontal ligament. Lift tooth out of socket without tipping the root mediallly. Remove any sharp edges of bone from the alveolus.

Question 50

What is the difference between mandibular canine removal technique?

Answer 50

The roots move medially within the mandible as they deepen, so that a lateral approach requires more bone removal as the roots become further from the surface towards the tip of the root.

Question 51

What is feline tooth resorption?

Answer 51

The initial lesion is an external surface resorption of the tooth by multinucleate cells alled odontoclasts. Hard tissue los starts in the root cementum progresses into the dentine and then moves up to involve the dentine of the crown. Eventually the enamel is also eaten away in a scalloped fashion giving the characteristic clinical lesion of a shiny bright red area on the crown surface. The red substance is a granulation like tissue filling in the enamel void. Almost always located on the buccal aspect of the tooth and certain teeth more affected - mandibular third premolars.

Question 52

How is feline tooth resorption diagnosed?

Answer 52

Cats may show irritability, changes in food preference, drooling and head shyness. Dental X ray the best method. Xraying 307 and 407 has been shown accurately to predict resorptive disease elsewhere in the mouth. a type 1 lesion: normal tooth root density and appearance, periodontal ligament space visible, often associated with general periodontal disease, about 40% of cases of tooth resorption are type 1. A type 2 lesion - roots hard to see, may be replaced by alveolar bone or ghosted in outline, periodontal ligament not clear, gingivitis associated.

Question 53

What is the treatment of feline tooth resorption?

Answer 53

Teeth should be extracted. Specialist referral may be considered for early and small lesions. Attempts to save the tooth or slow progression sing dentine bonding agents and restorative approaches may be made.

Question 54

Describe how extraction techniques differ for type 1 and type 2 lesions?

Answer 54

Type 1 lesions require standard extraction with root retrieval. If a root tip fractures it should be found and removed. Type 2 lesions can be treated with coronal amputation, the crown is amputated and no attempt is made to retrieve the rooots. coronal amputation is performed using a small bur after 1) incising the epithelial attachment of the tooth using a no11 scalpel blade in the gingival sulcus, 2 raising a small gingival flap on either side of the tooth,Post op analgesia for several days.

Question 55

What is feline chronic gingivo-stomatitis?

Answer 55

Condition appears to be an aberrant immune response to low levels of plaque antigens. Associations suggested with feline calicivirus, FeLV, FIV and FHV. increased numbers of cat sin household, gram negative anaerobes, purebreeds. The lesion is a submucosal infiltration of plasma cells, lymphocytes, macrophages and neutrophils. The inflammation can be focal or diffuse. The palatoglossal folds and the oral mucosa lying lateral to these and the mucosa around the cheek teeth are the most common sites for the marked inflammation that is seen.

Question 56

What are the clinical signs of feline chronic gingivo stomatitis?

Answer 56

Mouth pain, salivation, halitosis, reduced appetite, reduced grooming, submandibular lymph node enlargement, personality changes.

Question 57

What is the treatment of feline chronic gingivo-stomatitis?

Answer 57

Supply a 10day course of antibiotic, suitable choiices are clindaycin, amoxicillin, clavulanate, metronidazole, then perform a careful scale and polish including subgingival treatment, extract teeth affected by periodontal disease, supply chlorhexidine based gel for the owner to apply daily on an on going basis. Radical tooth extraction may be performed or steroid treatment. Removal of all cheek teeth, upper and lower quadrants, both sides. Steroids every 2-3 weeks untill remission, then every 6 weeks. Interferon - for cats non respoonsive to radical extractions.