Penny is a 5 year old German Shepherd that was kicked in the face by a horse. Aside from damage to several teeth, she sustained no other injuries. Penny was anesthetized and a thorough oral exam revealed that she had several fractured incisors with pulp exposure and an enamel fracture to the left maxillary canine (204).
Full mouth dental radio graphs were obtained in order to ensure no other teeth were damaged below the gum line. There was no signs of endodontic disease to 204. The fractured incisors were deemed unsalvageable and were extracted. A composite restoration was performed on 204 in order to eliminate sensitivity, decrease plaque and calculus accumulation and restore aesthetics of the tooth. As a result of her treatment at Veterinary Dental Specialists & Oral Surgery, Penny recovered great from the procedure and is back to playing with toys.
Enamel covers the coronal portion of the tooth and is the hardest substance in the body. It is composed of 96% hydroxyapatite crystals. Enamel is formed by ameleoblasts during tooth formation prior to tooth eruption. Once the tooth erupts no further enamel is produced. Enamel thickness in dogs is less than 1.0 mm. Below the enamel lays dentin, which is softer than enamel and is vital.(1, 3) In a normal healthy tooth, dentin continues to be produced throughout life by odontoblasts.(1,2) Dentin is composed of 70% hydroxyapatite crystals and 30% organic material, and is perforated with approximately 50,000 dentinal tubules per mm2. (1,3) These dentinal tubules extend from the pulp to the dentinoenamel junction which lies against the enamel on the coronal portion of the tooth. The dentinal tubules are filled with fluid and odontoblastic tendrils. Dentin exposure results in an increase of the fluids outward flow. This flow of fluid is theorized to stimulate mechanoreceptor nerves (A-delta or C-delta fibers) within the pulp, causing the sensation of pain. (1,2,3) This is known as the hydrodynamic theory of dentin sensitivity. This outward flow of fluid may help protect the pulp, but also creates a way for bacteria or toxins to enter the tooth and reach the pulp, leading to endodontic disease.(1,2)
Eventually, tertiary dentin is produced by odontoblasts in response to the stimuli produced by dentin exposure. This process can take up to 8 weeks to initiate, and additional time to complete the process. (2) Tertiary dentin protects the pulp by increasing the distance a toxin or bacteria must travel. This also allows the pulp more time to recover from the initial insult, if it is able. The formation of tertiary dentin varies with the degree of the stimuli. (1)
Alternatives to a full crown include bonded sealants and composite restoration. (2,3) A bonded sealant protects the area of dentin exposure for a period of 3-12 months as long as there is no further damage to the tooth.(2) This gives the tooth a chance to repair itself if it can overcome the initial insult. (1, 2) Composites can be further added at the site of the fracture to help restore tooth function and esthetics. (3) However, as in this case, a stronger material is recommended for teeth subjected to increased stress such as maxillary fourth premolars of patients that chew on hard objects. (4, 5, 6, 7) Dogs can exert a bite force up to 937 Newtons.(6, 7, 8)
- Startup S. Tooth Response to Injury. Veterinary Endodontics, 1st San Diego: Practical Veterinary Publishing 2011:10-24
- Theuns P, Niemiec B. Bonded Sealant for Uncomplicated Crown Fractures. J Vet Dent 2011: 28(2):130-132
- Greenfield B. Enamel Defect Restoration of the Left Mandibular First Molar Tooth. J Vet Dent 2012: 29(1):36-41
- Bellows J. Small Animal Dental Equipment, Materials and Techniques, 1st Ames:Blackwell Publishing 2004: 244-248
- Holmstrom SE, Frost P, Eisner ER. Veterinary Dental Techniques, 3rd Philidelphia:Saunders 2004: 462-480
- Coffman CR, Visser L. Crown Restoration of the Endodontically Treated Tooth: Literature Review. J Vet Dent 24(1);9-12
- Foreest A, Roeters J. Evaluation of the Clinical Performance and Effectiveness of Adhesively-Bonded Metal Crowns on the Damaged Canine Teeth of Working Dogs Over a Two- to 52-Month Period. J Vet Dent 15(1);13-20
- Lindner DL, Marreta SM, et al. Measurement of Bite Force in Dogs: A Pilot Study. J Vet Dent 14(1);49-51