Malocclusion

Malocclusion Veterinary Dentistry 2 – Lecture 5 Max incisors infront of mand incisors Mand canines between max canine & 3rd incisors w/ slight tilt outward Zig Zag pattern Teeth fit together like puzzle Max premolar & molar on buccal aspect of mand premolar & molar (Behind) Malocclusions - Misalignment of teeth Can cause cosmetic or cause trauma (ONF, attrition, fracture, tooth death – our concerns) The cause can be skeletal deformity or tooth related (tooth in abnormal position causing the issue) Pet must be comfortable & teeth functional – our role Dental Interlock - Jaw growth is independently regulated, each quadrant grows separately The proper mandible-maxilla relationship should be maintained throughout adulthood Examine the canine & incisor teeth on model skull The close relationship of the canine an incisor teeth enable a “push-pull” system to allow normal jaw growth (maxillary grows, canine pushes on bottom canine to encourage it to grow as well) Skeletal vs Dental Malocclusion Skeletal – inherited/breed specific, jaw length or width discrepancy - - Animal was born this was Results in crowding & rotation, bowing of mandible suggest shortening of jaw Extra space between premolars suggests lengthening, uneven occlusions of canine teeth Generally bilateral Dental – results from malposition of teeth that push other teeth out of their normal position causing malocclusion - Can result from retained deciduous teeth Adult maxillary canine erupts rostral to baby tooth Permanent mandibular canine erupts medial to baby tooth Permanent incisors erupt palatal to baby ones Max premolar 3 & 3 erupt palatal to baby tooth Max premolar 4 erupts Bucco mesial to baby tooth Mandibular premolar erupts lingual to baby Terminology: Jaws Abnormalities Prognathia – one jaw is in the forward position compared to the other Retrognathia – one jaw is in the caudal position compared to the other Brachygnathia – shortened jaw (underbite & crowding/rotation of teeth to be classified as such) Tooth Position Abnormality Terminology -version (tipping/angled) Mesio – Toward Midline =MV Disto – Away from Midline DV Labio – towards lips = LABV Bucco – Towards Cheek = BV Linguo – Towards Tongue = LV Palato – Towards Palate = PV Malocclusions Classification Class 1 – normal jaw length, 1 or more teeth out of alignment Class II – Mandible is shorter than normal Class III – Mandibular prognathism or maxillary Brachygnathism Class IV – Formally called “wry” bite – uneven jaw lengths (same jaw) each side of mandible uneven length MAL 1 - - Overall normal occlusion except 1 or more teeth out of alignment Charting Code = MAL1/___ enter specific type of misalignment Mandibular tooth/teeth have more buccal or labial position than the antagonist maxillary tooth = CB/R or CB/C = Crossbite (Rostral = incisors, Caudal = Pm,M) Caudal Traumatic Malocclusion in Cats – Contact between Mand M1 & Max PM4, occurs from Max PM 4 is slightly pallatoverted = can result in lesions/gingival recession (Maine Coone & Persians) MAL 2 - “overbite” Mandible is shorter than normal Problematic due to location of mandibular canines MAL 3 - “underbite” Mandibular prognathism – mandibular incisors occlude labial to maxillary incisors MAL 4 - “wry bite” Uneven length on same jaw (right vs left sides) Central incisors of maxilla and mandible do not align Many subclasses depending on direction of misalignment Treatment for malocclusions involve removing the problem teeth ASAP, hopefully before adult teeth erupt before malocclusion occurs. Orthodontic correction and alteration of tooth with endodontic work, ball therapy. Developmental Conditions Variations in number of teeth, size and their shape or how enamel forms Retained Teeth – Can become a big issue if not dealt with – always rad if you believe it is missing - Tooth doesn’t erupt it can lead to Dentigerous Cysts from enamel epithelium of tooth continuing to produce a fluid creating a pocket of fluid under the surface of the bone, degrading alveolar bone integrity. If not fixed can lead to facial swelling and complete loss of bone integrity Gemination - Small split in tooth, doesn’t typically reduce tooth integrity unless it surpasses gingival line, monitor Structural defects in enamel: Hypocalcified = soft, low calcium, normal amount of enamel Hypoplastic = normal hardness, not enough of it, thin layer or very pitted 2 Main Causes: - Hereditary – amelogenesis imperfecta Environmental enamel defects – trauma or disease early on in life Affecting deciduous teeth: day 42 gestation – 15 days post-partum Affecting permanent teeth: 2weeks – 12 weeks (ex from distemper) Localized = a few teeth, generally due to trauma Generalized = most teeth, from fever or systemic disease (ie Distemper) Clinical Significance & Treatment - Hypocalcified or hypoplastic Enamel sloughs off if not cleaning gentle enough, exposes pulp cavity Soft enamel = must be very careful when cleaning teeth