Flashcards in Dentistry Deck (56)
What is the crown of the tooth?
The part of the tooth that is above the gum. The crown consists of on or more cusps. A canine tooth has one cusp, a molar has several.
What is dentine?
The main substance of the tooth, it is 70% inorganic in compostion. 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 contained an odontoblastic process and sensory nerve. Dentine is not normally exposed to the environment, being covered by enamel.
When are primary, secondary and tertiary dentine laid down?
Primary dentine 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's tubular structure is less well organised and reflects light differently and its surface is more likely to absorb pigments.
What is cementum?
An avascuar and bone like mineralised connective tissue which covers the root. Cementum is constantly produced in life.
What is enamel?
The hardest tissue in the body, and is 96% inorganic material. Mainly Ca hydroxyapatite. Enamel thickness is around 0.2mm in cats and 0.5mm in dogs. Its formation is complete by the time of tooth eruption i.e it cannot repair itself.
What is the cemento-enamel junction?
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.
What i the pulp?
The soft centre of the tooth containing blood vessels, lymphatics, nerves and various cell types including odontoblassts. 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 open 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 space. pulp is also known as the endodontic system.
What are sharpeys fibres?
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, locking the tooth in place and also absorbing shock from chewing motions.
what is the alveolus?
The area of jaw accommodating the tooth, the dental socket. The socket walls are known as the cribiform plate and show up on xrays as a dense line, the lamina dura. The cribiform plate supports attachments from the periodontal ligament. The area of bone surrounding the neck of the tooth is the alveolar margin.
What is the gingiva?
The gums, tough tissue forming a cuff around each tooth. There are two types, the frer gingiva around the tooth surface and hthe attached gingiva bound tightly onto the underlying periosteum of the alveolar bone. the gingival sulcus is formed between the tooth and the free gingiva. It exists as a small pocket which is up to 1mm deep in cats and 4mm deep in dogs. Deeper pockets indicate tooth disease and attachment los.
What is the periodontium?
The supporting structures of the tooth. Consists of the cementum, the periodontal ligament, the alveolar bone and the gingiva.
Describe the main blood vessels and nerves of the tooth
Arterial supply > common carotid a. > external carotid a. > maxillary a. > mandibular a.
Trigeminal n. (cranial nerve V) > maxillary n. and mandibular n.
Describe the blood supply of the mandibular teeth
The mandibular artery enters the mandible at the mandibular foramen and becomes the inferior alveolar artery. It runs within the mandibular canal and exit at the mental foraminae, where branches are now called the mental arteries. Along the way, small branches supply individual teeth by penetrating the periodontium. the inferior alveolar branch of the mandibular nerve accompanies the inferior alveolar artery and vein in the mandibular canal.
Describe the blood and nerve supply of the maxillary teeth?
The maxillary artery and its branches supply these teeth. the main branch running within the infraorbital canal s the infraorbital artery. The infraorbital nerve which is also a branch of the Trigeminal nerve accompanies it and gives off caudal, middle and rostral superior alveolar branches.
Why do teeth hurt?
Sensory nerves are present in the dental pulp. They enter the pulp through the root apex/apical delta along with arterioiles, venules and lymphatics. Direct pulp damage causes pain. Exposed dentine is also painful 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.
What is the dental formula of the dog?
primary teeth - 2x I 3/3 C 1/1 PM 3/3 M 0/0
Permanent teeth 2x I 3/3 C 1/1 PM 4/4 M 2/3
What is the dental formula of the cat?
Primary teeth 2 x I 3/3 C 1/1 PM 3/2 M 0/0
Permanent teeth 2 x I 3/3 C 1/1 PM 3/2 M 1/1
When should teeth be through in puppies and kittens?
Deciduous teeth - there are no teeth at birth. Canines - through by 4 weeks. Incisors and premolars - through by 5-6 weeks. All primary teeth are usually present and correct by 6 weeks in both kittens and pupies. 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.
What is normal tooth occlusion?
Scissor bite of incisors i.e upper incisors sit slightly rostral to lower. the lower incisors engage with the cingulum (ridge) of the upper incisors. Lower canine rostral to upper, evenly occupying the space between the upper canine and the 3rd upper incisors. Premolars and molars inter digitate in a pinking shear fashion. Upper carnassial lingual aspect engages with lower molar buccal aspect.
What are the causes of malocclusion?
Skeletal malocclusion - i.e pertaining to jaw bone length or width. usally considered inherited.
Dental malocclusioon - the tooth positioning within the jaws, other than in certain breeds, usually considered acquired. so both genetic, environmental/developmental factors can be involved in malocclusions. Inherited aspect is probably polygenic
What is an undershot jaw?
Mandible is longer than it should be. Also called mandibular prognognathism. mandibular canine is not sitting evenly in the spac ebetween upper 3rd incisor and maxillary canine, may touch the upper 3rd incisor, loss of premolar pinking shear, loss of incisor scissor bite, upper incisors may be caudal to lower.
what is an overshot jaw?
Mandible is shorter than it should be. Also called mandibular brachygnathism. 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. Loss of premolar pinking shears.
What is a wry bite?
Lop sided growht of head producing a crooked bite and a twisted face. Narrow mandible common. Mandible width too small in relation to maxilla. Result: bottom canines grow into hard palate in position medial to the upper canines. Typical clinical signs include quiet, head shy puppy, picky appetite and poor growth, oronasal fistula. made worse by retained primary canines as the permanents will come in even more medially. The malocclusion cann produce a dental iinterlock which prevents normal growth of the mandible resulting in ventral bowing of the mandible as the continued growth has to go somewhere.
What are persistent primary teeth?
Mainly the canines and incsors, and commonor in small breeds where it seems to have a familiar inheritence pattenr. the problem is that the retaied teeth interfere with the eruption path of permanent teeth. There should never be a corresponding deciduous and permanent tooth of the same type in the same place. Persistent deciduous teeth should be removed as soon as they are noticed since delaying removal can add to problems.
What is the treatment of malocclusions?
If nto causing problems or not likely to then no treatment is needed. Treatments: extrac persistent primary teeth as soon as possible, this will minimize problems. dont wait hoping they will fall out. This risks causing problems for incoming permanents. Other general treatment principles are orthodontics - relatively infrequently performed, tooth shortening or reshaping with endodontics if the pulp cavity is breached. Extraction - best option.
Describe the pathogenesis of periodontal disease
Primary aetiological agent is plaque. Supra gingival and sub gingival plaque accumulates> bacteria colonise > initial bacteria are aerobes and facultative anaerobes, and condition progresses> oxygen levels in gingival sulcus reduce > anaerobes take over > periodontal pockets form due to tissue destructive actions of bacterial toxic by products.
What is Plaque?
75% organic including food residues, 25% inorganic component, contains glycoproteins and polysaccharides which glue the plaque on to the tooth surface. Mineralised plaque is calculus which is usually seen on the buccal aspect. thick layers can build up as more plaque gets deposited on top. the main problem on calculus is as a plaque retentive surface, calculus is not irritating or inflammatory.
How does periodontal disease progress from normal to severe periodontitis and tooth loss?
Normal gingiva > plaque > inflamed gingival margin (gingivitis) > fluid (neutrophiil rich) accumuates in the 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.
Describe the diagnosis of periodontal disease?
1. degree of gingivitis - measured from 0 to 3 (ulceration and spontaneous bleeding of gingiva) uncomplicated gingivitis is fully reversible with prophylaxis (scaling and polishing). 2. - ersults of periodontal probing - this is an important phase of the examination with several possible results.
Supre bony pocket: involves the soft tissue only
Infra bony pocket: pocket extends into alveolar crest bone which is destroyed
Pseudo pocket - caused by hyperplastic gingiva which migrates towards crown and so the sulcus depth appears deeper than normal.
Receded gums and horizontal bone loss: gingiva recedes and bone crest also recedes so pocket depth appears normal but the root surface can be eposed and periodontal disease can be severe.