Etiology of Malocclusion

1. 1 Etiology of malocclusion Etiology of malocclusion Prepared by Prepared by Dr. Mohammed Alruby Dr. Mohammed Alruby Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

2. 2 Etiology: in orthodontics, is the study of actual causes of dento-facial abnormalities Malocclusion: = a condition where there is a deviation from the usual or accepted relationship = dental malocclusion exists when the individual teeth within one or both jaws abnormally related to each other, this condition may be limited to a couple of teeth or involving the majority of teeth presents. Orthodontic equation: is an expression of the development of any dento-facial deformity Cause --------- acts at a certain time --------- on tissue – produce --- results cause time tissue Results 1-Hereditary 2-Developmental of unknown origin 3-Trauma 4-Physical 5-Habits 6-Diseases 7-malnutrition It is important to know the following: 1-onset 2-duration 3-frequency 1-neuromuscular tissue 2-teeth 3-bone cartilage The severity of dentofacial deformity depend on: 1-the nature etiologic factor 2-time of onset, duration and frequency of primary etiologic factor 3-the resistance of the tissue of primary and Primary etiologic sites: 1-Neuromuscular system: The muscle group that serve most frequently as primary etiologic sites are: == muscles of mastication == muscles of facial expression == tongue The neuromuscular system plays its primary role in the etiology of dentofacial deformity by the effect of abnormal contraction of bony skeleton and the dentition. Both bones and teeth are affected by the many functional activities of orofacial region 2-Bone: Since the bone pf maxilla and mandible serve as bases of dental arches, changes in dental arches growth may alter the occlusal and functional relationship. 3-Teeth; The teeth may be primary sites in the etiology of dentofacial deformity in many ways Gross variation in size and shape are encountered frequently and always are of concern Decrease or increase in the regular number of teeth will give rise malocclusion Etiologic factors: A-Extrinsic factors: 1-Evolution: With evolution, the jaws become smaller, reduction in number and size of teeth and diminution of jaw projections together with increased in vertical height of the face and there is a retrognathic tendency in mans as he ascends the evolutionary scale 2-Heredity: Transmission of dentofacial characteristics through generations by genes. Most authors between 1900-- 1920 did not completely determine the role of inheritance in determination of the form, size and proportion of dentofacial skeleton, but they stress their work upon the effect of the Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

3. 3 environmental factors, and at this time they were hardly belief that the effect of local lack of function is more important. Bennet statement: the size, form and density of bones such as maxilla and mandible varies according to the extent to which these structure are used during period of growth – (function stimulate growth) Walk Joff statement: the form and degree of development of maxilla and mandible depends upon the magnitude of functional stimuli of muscles acting upon these structures. Baker: his study was performed on animals by unilateral amputation of muscles of mastication, he found lack of growth on the affected side. Brash: studied the facial form and the dental development in twins on genetic bases, he also emphasized the genetic facial pattern of some royal families in Europe where they had been inter- marriage, his studies gave the best evidence to support the role of inheritance Axel Lundstorm:1925 showed that, the form and size of dental bases and the teeth are genetically determined, when the size of the teeth and their basal arches are not correlated, problems of crowding or spacing will be arising. Broadbent and Hofrath 1931: developed standardized cephalometric x-ray technique which permit serial longitudinal studies of facial growth, by this studies the concept of inheritance growth pattern arises There are three types of transmission of malocclusion from the standpoint of genetics: a-Repetitive: the recurrence of single dentofacial deviation within the immediate family b-Discontinuous: a tendency for mal-occlusal trait to reappear within the family over several generation c-Variable: the occurrence of different but related types of malocclusion within several generation of the same family Dental defect of genetic origin includes the following: 1-Crowding and spacing of teeth 2-Size and characteristic of the soft tissue including muscles and Frenum 3-Facial a symmetry 4-Macrognathia and Micrognathia 5-Macrodontia and Microdontia 6-Oligodontia 7-Tooth shape variations (peg shaped lateral incisor) 8-Mandibular retrusion 9-Mandibular prognathism 10-Median diastema 11-Upper face height, nose height, bi-gonial breadth 12-Bimaxillary protrusion NB: hereditary ectodermal dysplasia: it is a sex linked anomaly transmitted by the unaffected female to their male offspring, and has the following manifestation: == soft and thin dry skin with absence of sweet gland == frontal bossing and depressed nose == thick hypotonic lip == Oligodontia and complete anodontia == delayed eruption of teeth == maxilla and mandible are normal size but the present teeth are widely separated == the incisor may be peg shape or conical Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

4. 4 3-Congenital: Deformities either heredity or non-heredity origin but exciting at birth a-Cleft palate: = Lack of fusion of two palatal process to each other, various studies have shown that from one third to one half of all cleft palate children have familial history of this deformity. = Classification of clefts: Class I: soft palate cleft with possible notching of hard palate Class II: soft and hard palate but not alveolar ridge Class III: complete unilateral lip jaw palate right or left Class IV: complete bilateral lip jaw palate = As with non- cleft child, palatal, pharyngeal and perioral musculature is well developed at birth to meet the demand of suckling, deglutition and mastication. = While the complete unilateral cleft and complete bilateral cleft break the continuity of the upper lip and disturbs the functional pattern and significantly reduces the restraining effect of the buccinators mechanism that produce malocclusion = Cleft palate may lead to: -Underdevelopment and retruded maxilla due to continuation of the oral cavity to nasal cavity that affect the pressure of air cells in the nose and maxillary sinus that stimulate growth of maxilla -Excessive intraoral clearance -Lingual tipped incisors b-Cleft lip: The common cleft is the upper lip as a result of failure of globular process with maxillary process, this cleft lead to discontinuity of buccinator mechanism that lead to protrusion of anterior teeth c-Cerebral palsy: a paralysis or lack of muscular coordination due to inter-cranial lesion There is a varying degree of abnormal muscular function may occur in mastication, deglutition, respiration and speech. This uncontrolled muscle activity gives rise difficulty in establishment and maintenance of normal occlusion The electo-myographic studies on cerebral palsied children showed significant difference in the level of activity even when muscles are not in active function d-Torticollis: Wryneck Foreshortening of the sternocleidomastoid muscle can cause profound changes in the bony morphology of cranium and face Facial a symmetry with dental malocclusion may be created if this problem not treated fairly early e-Cleidocranial dysostosis: another congenital defect that characterized by: -Unilateral or bilateral complete or partial absence of the clavicle -Delayed closure of cranial suture -Maxillary retrusion of due to underdevelopment of it -Mandibular protrusion -Retarded eruption of permanent teeth -Retained deciduous teeth -Supernumerary teeth are common -Underdevelopment of paranasal sinuses -Multi-impacted tooth f-Mandibulo-facial dysostosis: characterized by; Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

5. 5 -Hypoplasia of facial bones especially zygomatic -Marked hypoplasia of mandible ------ bird face appearance -Crowding and malposition of teeth -Agenesis of malar and palatine bone --- cleft palate -Anomalies of external ear g-Micrognathia: Abnormal small jaws maxilla or mandible may be affected Mandible: sever retrusion of chin Steep mandibular plane Retrognathic profile Deficient chin button Maxilla: retruded middle third of face Deficient premaxilla Prognathic profile h-Macrognathia: Abnormally large jaw, may be true due to the actual prognathism of jaw or relative due to underdevelopment of one jaw to the other i-Pierre Robin’s syndrome: Micrognathia -- glossoptosis -- cleft palate May be associated with other abnormalities such as mongolism, atresia of ear and absence of TMJ j-Cleft mandible: midline defect result from failure of union between left and right mandibular process k-Tongue tie: is congenital condition caused by shortness or excessive anterior prolongation of Frenum linguae of the under surface of tongue. Effects: restriction of normal tongue function that cause: -Constriction of maxillary arch -Difficulties in eating -Periodontal disease in mandibular segment Ankylglosum superior syndrome: rare condition characterized by: -Tongue congenitally attached to the hard palate or maxillary alveolar ridge -Hypodontia -Microglossia -Anomalies of extremities l-Microcephaly: Congenitally anomaly in which = the brain development is retarded, and it is smaller than normal = cranial dimensions are affected as well as the volume = skull is small because of a lack of brain growth = none of cranial sutures is closed, but since the brain does not grow = the demand of sutures is absent = in a number of chromosomal anomalies, microcephaly is present with varying degree of mental retardation m-Hydrocephaly: Spinal fluid fills the cranium and causes the enlargement of cranial vaults. = The sutures of the cranial bones are separated and new bone formation tends to close the gap and the cranium may be double its volume = Mental retardation may occur and it is not a necessary component because the pressure influences the vault rather than the brain = cranial base not affected severely, and face may grow normally = the jaws and occlusion of teeth are not directly involved = Although the face looks larger in microcephaly and smaller in hydrocephaly is only relative to the size of the cranium n-Craniostenosis: Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

6. 6 = Sutures of the cranial vault may be fuse prior to the complete growth of brain depending on the sutures involved = cranium is deformed in bizarre shapes turricephaly, scapho-cephly without necessarily causing brain damage, if however, many are fused the brain growth is confined as an inadequate space and pressure may build to such a point as to cause the brain to flow through the foramen magnum and brain growth in not enough to cause expansion. = the weakest area in the anterior cranial base during five years of life is the ethmoid, so the increased intra-cranial pressure may deflect the ethmoid complex downward. This lowering the perpendicular lamina of the ethmoid, which influence the vertical position of the palate which in turn influence the vertical rotation of the mandible. = thus the primary disturbance in the cranial base may secondarily influence the position of maxilla and mandible and thereby the facial proportion and dental occlusion. o-Platybasia: = Occur as in case of mongolism, the angle between the anterior cranial base and posterior cranial base is obtuse angle in such degree to appear as straight line. = This occur due to lack of development of occipital bone to grow downward and thus keeping the glenoid fossa high so the mandible is not rotated = there is apparent open mouth that may be due to relatively large tongue in reduced oral cavity NB; Platybasia may occur in case of hypothyroidism as there is a lack of development of sphenoid complex and this influence the midface When the sphenoid fails to grow upward, the posterior end of palate remains low relative to the condyle and tends to induce mandibular rotation downward and backward resulting in open bite p-Microglossia and a glossia: Rare condition characterized by small or rudimentary tongue, a glossia is very rare condition in which the tongue is completely absent Effect: difficulty in speech and eating, collapse of dental arch due to high action of buccinator q-Macroglossia: Abnormal large tongue Effect; 1- spacing and flaring of the teeth 2-tongue thrust 3-abnormal tongue posture over the occlusal surface 4-difficulty in eating, respiration, swallowing and speech r-Macrochelia: Enlarged lower lip, flaccid and everted. It is often hypotonic, so that there is lack of pressure against mandibular teeth that result in protrusion s-Hypertelorism: = lateral position of eye due to widening of the bridge of the nose = incomplete development of maxillary process = incomplete development of mandibular rami 4-Environmental a-Prenatal influences: Nutritional deficiencies: = the mother suffering from lack of calcium, phosphorus, vitamin B C and D are able to have malformed children = half of pregnant women who have congenitally malformed offspring exhibit the signs of anemia = large varieties of congenital malformation have been found in newborn infant of mother with sever vitamin A deficiency Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

7. 7 = Riboflavin deficiency may cause malformation, administration of Riboflavin to pregnant rat was fond to prevent some malformation = acute folic acid deficiency may cause cleft palate, retarded growth and deformities of bones Rubella: Acute viral infection usually occurs in epidemic form, maternal rubella of pregnant mother is considered as a possible cause of wide spread congenital malformation such as, blindness, deafness, and cardiovascular abnormalities. The most common dental effect is: enamel hypoplasia high caries index delayed eruption of teeth Radiation: When pregnant mother exposed to radiation especially during the 1st six weeks of first trimester, the fetus may be damaged even with small dose, the malformations of radiation are: Cleft palate mongolism microcepalus hydrocephalus deformed limb Abnormal intrauterine position: That interfere with symmetric development of face and jaws, a symmetry of the head may caused by the pressure of the shoulder or extremities against the head Chapple and Dawidson; determined the position of comfort of the fetus, they found that many infants with signs of pressure on mouth and jaws. This pressure is caused by one or both legs had been extended across the body bringing the foot against the side of the head forcing it against the opposite shoulder, thus causing facial a symmetry and deviation of the mandible b-Postnatal influences: 1-Birth injuries with high forceps delivery is common and may cause ankylosis of TMJ which effect the condylar growth center and thus interfere with normal mandibular growth, this condition may be unilateral or bilateral Unilateral ankylosis: interfere with the normal growth of the mandible at the affected side while the other side grow normally, this result in shifting of the mandible toward the affected side that lead to malocclusion Bilateral ankylosis: interfere with normal growth of the mandible as a whole resulting in mandibular Micrognathia, the mandible cannot grow normally to accommodate all the permanent teeth that lead to crowding NB: injury of the facial nerve may occur at birth by birth instrument lead to transient or permanent facial paralysis 2-Deformation of upper jaw during delivery due to the obstetricians frequently insert the fore- finger and middle one into baby’s mouth to ease passage through the birth canal, and because the plasticity of maxillary and pre-maxillary region this lead to permanent damage 3-Extensive scar tissue result from major surgery operation 4-Strong elevating force on the mandible as a result of wearing a plastic neck cast for long period 5-Strong force during delivery produce fracture of the condyle 5-Endicrine imbalance: = no tissue in the body is escape from some sort of hormonal influences either in the course of its development and growth or in functional activities = from this point of view it is very important to study the effect of disturbances in hormone metabolism on occlusion a-Pituitary gland: Small body in the base of brain and rest in hypophyseal fossa of sphenoid bone and considered as a master gland in the body Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

8. 8 Hypo-pituitarism: pituitary dwarfism: The disturbance occurs before puberty (hypo-secretion): that lead to; = delayed eruption and shedding time of teeth as the growth of the body as general = root of the teeth is shorter than normal = dental arch is smaller than normal and cannot accommodate all teeth so that malocclusion is developed = retarded osseous development of mandible than maxilla = delayed apical closure = hypothyroidism and diabetes insipidus Hypo-pituitarism in adult: Simmond’s disease: Occur after puberty due to infarction of pituitary gland and characterized by: == decrease sexual function == loss of weight == atrophic change in skin == no specific dental features Hyper-pituitarism before puberty: Gigantism that characterized by: = root of teeth longer than normal = upper part of body is shorter than normal = spacing of teeth = ossification of cartilaginous center is delayed and the fontanelle may persist to the time of adolescence Hyper-pituitarism after puberty: Acromegaly: = lips are thick and negroid = tongue enlarged and show indentation = teeth in mandible are tipped buccal or labial due to enlarged tongue --------- spacing teeth = mandible is large size due to accelerated condylar growth, there is appositional and remodeling changes in all area of mandible b-Thyroid gland: Highly vascular bilateral lobed u shaped gland located on the trachea, it stimulates basal metabolic rate and control general metabolism by increase oxygen uptake by the tissues Hypothyroidism: congenital type: Cretinism Failure of thyroid gland to produce sufficient hormone to meet the requirement of the body = shortening of the base of skull = mandible is under-developed; maxilla is over-developed (relative) = retardation in normal rate of deposition of calcium in bones and in the development of tooth buds in the fetus = defect facial height = tongue enlarged and protruded which may result in malocclusion = delayed shedding of primary teeth = delayed eruption of permanent teeth Hypothyroidism: childhood type: Juvenile Myxedema; after 6 years and before puberty = enlarged tongue by edema fluid that protruded continuously and this lead to malocclusion = delayed carpal and epiphyseal calcification = delayed eruption rate of teeth and deciduous teeth are retained beyond the normal shedding time = irregularities of teeth arrangement and open bite may be present as a result of tongue enlargement Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

9. 9 = osteoporosis and periodontal disease =abnormal dental calcification and root resorption = in adequate development of maxilla and depressed nasal bridge Hypothyroidism: adult type: Myxedema: = edema of soft tissue of mouth, face, lips, and nose = tongue enlarged and edematous and interfering with speech and occlusion = osteoporosis of bone NB: Myxedematous swelling: is a probably an extra-vascular cellular accumulation of water and protein in the tissue Hyperthyroidism: hyper-function of thyroid gland = alveolar atrophy in advanced cases = shedding of deciduous teeth is earlier than normal = accelerated eruption of permanent teeth = patient has facial expression of surprising or excitement; the patient is usually nervous and very uncooperative c-Parathyroid gland: Four small glandular bodies embedded in the back of thyroid gland, regulate calcium and phosphorus metabolism Hyper-parathyroidism: Von Recklinghausen’s disease of bone: = High osteoclastic activity and withdrawal of calcium from the bony skeleton due to bone resorption, there is a sudden drifting of teeth that lead to spacing = pathologic fracture may occur, lamina dura is absent = Giant cell tumor or cystic lesion of the jaw are the first oral signs = malocclusion occurs due to shifting and spacing of teeth = in growing children, there may be marked interruption of teeth development Hypo-parathyroidism: low calcium level below 10mg/100ml: = increase neuromuscular excitability ----- Tetany due to low Ca level = aplasia or hypoplasia of teeth when the effect occur before the teeth were entirely formed = large pulp chamber and irregularities of occlusion = delayed resorption of primary teeth roots = delayed eruption of permanent teeth d-The Adrenals: Paired organs situated near the upper surface of each kidney, consists of outer layer(cortex) and inner layer (Medulla) = in adreno-congenital syndrome, the teeth show acceleration of development and eruption = when adreno-congenital syndrome begins in uterus it is characterized by ISO sexual with development of internal sex organ, but the external organs show pseudo hermaphrodite = tumor of adrenal gland at the time of tooth development may produce pre-mature eruption of permanent teeth Adrenocortical hyper-function: Decrease in protein body mass including the bony matrix to Ca deposited when the bone is formed that interfering with bone and tooth formation: Show: hermaphrodite Early appear of sexual hair Acceleration of tooth eruption and bone age NB: Cushing’s syndrome: Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

10. 10 = characterized by adrenocortical hyper-function = obesity in upper part of body (neck-face) ---- moon face = muscle weakness = there is premature epiphysis closure in children = high rate of physical growth = accelerated eruption of the teeth = osteoporosis of bone in adult e-Hypothalamus: Make up the third ventricle of the brain, the hypothalamus provides neurogenic of pituitary gland which control the target glands as; thyroid, adrenal, and gonads or it may affect the target gland directly f-The Thymus: Generally, it atrophied at the age of 14 to 16 years but with over growth of the thymus = the general body growth is accelerated = hypertrophy of the thymus gland may result in delayed eruption of deciduous teeth and poor tooth calcification g-The Gonads: = Excreted by the ovaries and tests, imbalance of osteogenic hormones may result in gingivitis, gingival hyperplasia and periodontal disease = burning sensation of tongue and decrease salivary secretion = exert marked influence in somatic growth = in hypo-function, the closure of the epiphysis is retarded = in hyper-function, advanced puberty occurs with early closure of the epiphyseal growth center and retardation of body height h-Precocious puberty: Occurs as a result of disturbance in hypothalamus, pituitary, adrenal, and Gonads = growth accelerated at first but followed by advanced epiphyseal closure = accelerated height and weight and advanced bone age = teeth may accelerate in development and eruption 6-Disease: = As exanthematous fever are known to upset the development time table of eruption, resorption and tooth loss. Some specific disease may be potent marker of malocclusion, disease with paralytic effect such as poliomyelitis are capable to produce malocclusion = disease with muscle malfunction such as muscular dystrophy and cerebral palsy also have a characteristic deformity on the dental arches 1-Bone disease: a-fibrous dysplasia: characterized by fibro-osseous formation and arise as: = expansion and deformity of the jaws = disturbance of eruption pattern of teeth because loss of normal support for teeth = mal-alignment, tipping or displacement of the teeth b-cherubism: = enlargement of the jaws Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

11. 11 = alveolar ridges are wide lead to narrow palate to V shaped and tongue is forced backward, and this interfere with swallowing and breathing = there is ma-alignment and malformation and irregularities of the teeth c-Achondroplasia: Disturbance in the endochondral bone formation which result the characteristic form of Dwarfism = maxilla is retarded due to restriction of growth of the base of the skull with mandibular prognathism = dis-proportion in the size of the two jaws that lead to malocclusion 2-Temporomandibular articulation disturbance: = ankylosis interfere with mastication, mouth hygiene and dental treatment = ankylosis early in life interfere with jaws growth and normal teeth alignment = in unilateral involvement of the condyle there is marked facial a symmetry in early unilateral arrest of condylar growth, there may be complete lingual occlusion of the mandibular teeth on the unaffected side = in bilateral arrest there is a symmetrical of deformity with marked retruded mandible 3-Arthritis: Sarnat 1994; distinguish four types of arthritis: == infectious arthritis: the synovial membrane may become infected; suppuration may cause destruction of the articular surface and the mandibular movement may be reduced and secondary cuse condylar ankylosis == rheumatoid arthritis: chronic and progressive inflammation involve the synovial membrane and then extend to the capsule and the articular surface of the condyle, then ankylosis occur == degenerative arthritis: characterized by progressive erosion of the disc and articular surface bringing the bone of the fossa and the condyle into contact, the muscular spasm may be developed == traumatic arthritis: the ligament and synovial membrane may be damaged by a severe blow and this will impose limitation of the mandibular movement accompanied with pain 4-Allergy: = children subjected to nasal allergy, bronchial asthma and allergic rhinitis often have nasal obstruction and mouth breathing which is common etiologic factor in development of malocclusion = respiratory allergy can affect the craniofacial skeleton as following: -Underdevelopment of maxilla in 3 planes -Mandible and tongue often occupies low posture and free the oral air way which result in extrusion of buccal teeth and bite opening -High and narrow palate -Protrusion of maxillary incisors -Buccal cross bite 5-Anemia: Considered as a general debilitating disease which effect the metabolic activities of the body and markedly effect the general growth and development of the body and markedly effect the general growth and development of body due to low oxygen carrying capacity of the blood = chronic long standing anemia during childhood may result in dentofacial underdevelopment especially of persist during active growth periods = Sickle cell and Cooley’s anemia causes marked bony changes in the form of osteoporosis 6-Chronic glomerular nephritis: It is an autoimmune disease characterized by - Hypokalemia: muscle weakness and fatigue - Hypocalcemia; osteoporosis - Secondary periodontal disease Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

12. 12 = muscle weakness and osteoporosis may cause atrophic changes and underdevelopment of jaw bones = pathologic fracture 7-Amyloidosis:serious conditions caused by a build-up of an abnormal protein called amyloid in organs and tissues (defect in protein metabolism) = in tongue lead to enlarged tongue --- and its sequelae 8-Hurler syndrome: Excessive intracellular accumulation of chondroitin sulfate and hepartine sulfate(carbohydrate metabolism) -Thick lips -Large tongue -Short mandible -Greater distances from ramus to ramus lead to spacing of the teeth -Delayed time of eruption 9-Rheumatic chorea: It is sudden, purposeless, jerky movement of muscles in any part of the body When it is affect the tongue cause it to move involuntary exerting much force upon dentition and later tongue become hypotonic 7-Nutritional deficiency: Nutritional deficiency and craniofacial growth: Guilford 1874 reported that the nutritional deficiency is strong predisposing factor in the dentofacial deformity, growth retardation is observed in children with chronic malnutrition, correction of dietary deficiency causes an acceleration of the skeletal malnutrition. Dietary requirements in growing children varies with age, size and body weight. Nutrition require the following factors: -Food intake -God slandered digestion -Proper absorption -Good metabolism for the food -Treatment of infectious disease the cause diarrhea and so forth Proper nutrition is an important factor during orthodontic treatment hence proper teeth movement depend on proper response of bone which undergo a process of resorption and reorganization in response to teeth movement Nutrition and malocclusion: The effect of diet in malocclusion is probably exerted through the impaired development of teeth and bones. Malnutrition can also affect the occlusion through dental caries, periodontal disease, loss of teeth, retarded development of the jaws and impaired masticatory function Nutritional factors in relation to the dentition and occlusion: -Acidic diet favor dental caries and alkaline diet reduce dental caries -Normal calcium phosphorus metabolism is very important in formation of sound teeth -Various disease due to vitamin deficiencies as Rickets show well defined correlation with dentofacial abnormalities -Higher Ca requirements are required during pregnancy and lactation to provide normal growth of bone and teeth. -In Rickets, Osteomalacia, and hyperparathyroidism, the amount of Ca excretion is greater than the intake which will result in depletion of Ca supply in bones and withdrawal of Ca from bone that result in osteoporosis and bone deformities Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

13. 13 Nutrition and teeth: Diet can affect teeth in two distinct ways: Local way: -Acidic diet intake increases the tendency of dental caries and thus loss of teeth may cause malocclusion -Intake of soft diet which not need considerable masticatory effort, may has damaging effect on dentofacial structure as: = atrophy and muscle weakness = lack of proper gingival message which required some hard food rich in cellulose and so that, atrophy of gingiva and periodontal disease = weak muscle lead to underdevelopment of jaws Systemic way: -The balanced diet is very important during tooth development, in order to allow normal differentiation and calcification of the teeth as: = Vit. D increase calcification of teeth Vit D deficiency: 1-Rickets 2-Delayed closure of fontanelle and cranial sutures 3-Early loss of deciduous teeth 4-Maxilla is narrow and the palate is high 5-Retarded eruption of teeth 6-Irregularities of teeth and malocclusion The lack of vit D (Rickets) may cause rachitis degeneration as the calcification stage of the proliferating cartilage does not occur and the functional remodeling of the condyle does not occur and the functional remodeling of the condyle does not continue and this arrest their growth Vit A deficiency: 1-Disturbance in differentiation and appositional growth of the developing teeth 2-Disturbance in calcification of teeth 3-Retardation in eruption 4-Disturbance in periodontal tissue 5-Hypertrophy of occipital and temporal bone that lead to reduction in size of posterior cranial base 6-Retardation of general dental growth = Vit A and D are very important for development of sound periodontal tissue = Vit B group are of special value in promotion of growth, include group of water soluble vitamins Vit B1: thiamin: important to optimize the growth and its deficiency may cause muscle weakness and edema of oral soft tissue Vit B3: growth promoting factor and prevent weight loss Vit C: ascorbic acid; important for formation of collagen organic matrix of teeth, bones, tendons, and wall of blood vessels Deficiency; looseness of teeth and gingival recession due to low rate of turnover of collagen fibers NB: Fluoride: is very important in prevention of dental caries Administration during the period of teeth formation increase tooth resistance to caries, Because the fluoride ions will incorporate into enamel in the form of fluro-aptite crystals During enamel formation Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

14. 14 On the other hand, hyperflurosis may interfere with normal formation of enamel causing enamel hypoplasia or pitted enamel 8-Abnormal pressure habits == the dentist must realize that the term rest is a comparative appraisal pressure are still being exerted on the teeth and bony support. Normally these pressures together with the functional forces have stabilizing, balancing effect on dentition == the effect of pressure on the growth of the human skull were noted by Darwin 1868 == the pressure habits which interfere with normal growth and function include finger sucking, lip and tongue biting on abnormally firm substances which produce abnormal pressure in the dentofacial region == the relation between incidence of pressure and malocclusion is statistically significant NB: habits can be classified into 1-Useful: habits of normal function as correct tongue position, proper respiration, proper deglutition, and normal use of lips in speaking 2-Harmful: include all that exert stress against the teeth and dental arches Thumb sucking: It is repeated forceful sucking of the thumb with associated strong buccal and lip contractions, the clinical aspect of this problem are divided into three distinct phases of development: Phase I: normal and subclinical significant thumb sucking: This phase extended from three months to three years as most infants display a certain amount of thumb sucking during this period, particularly at the time of weaning. Ordinary, the sucking is naturally resolved toward the end of this phase and the use of rubber pacifier is much less harmful than vigorous thumb sucking. Some children chew on finger during teething but this activity ceases when the teeth erupt. Phase II: clinical significant thumb sucking: This phase extended roughly from three to four years and sucking plasticized during this time will result in temporary damaged to the child. A definite and firm program of corrected occlusion is indicated at this time. Phase III: active thumb sucking: The child continuing this habit after four years of age that lead to development of malocclusion. This type of malocclusion dependent upon the position of the thumb during sucking and associated muscle contraction of the cheeks. Effects: 1-Protrusion of the maxillary anterior teeth. 2-Spacing of upper anterior teeth. 3-High palatal vault. 4-Retraction of mandibular anterior teeth. 5-Crowding of mandibular anterior teeth. 6-Excessive over-jet. 7-Class II division 1 malocclusion and sometimes class III when the mandible is pulled forward. Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

15. 15 8-High negative pressure within the mouth, with narrowing of maxillary arch that upset the force system in and around the maxillary complex. So it often impossible to the nasal floor to drop vertically to the normal position during growth. N B: the severity of the effects produced by thumb sucking will depend on its force, duration, and frequency. Tongue thrust and abnormal swallowing habits The subject of tongue thrusting and abnormal swallowing habits is extremely controversial, and the correlation between these habits and dental malocclusion is to establish. Firstly, we need to give an idea abnormal swallowing as follow: Normal infant swallowing: = the tongue lies between the gum pads. = the mandible stabilized by the contraction of facial muscles. = the buccinators muscles are strongly acting. = this type is present in the neonate and gradually disappears with the eruption of the buccal teeth in primary dentition. = the cessation of the infant swallow and appearance of mature swallow is not on and off phenomena but there is a transitional period or transitional swallowing. Normal mature swallowing: = teeth present in centric occlusion. = muscles of facial expression are in rest. = contraction of the elevator muscles to bring the teeth into occlusion. = very little lip and cheek activity 1-Simple tongue thrust swallowing: = Contraction of the lips, mentalis, mandibular elevators muscles. = The teeth are in occlusion (teeth together swallowing) but the tongue is thrust to give an anterior seal for the open bite. = The open bite is well circumscribed and has definite beginning and ending, this open bite is due to thumb sucking. = The incidence of simple tongue thrust swallow is diminishing with increasing the age. 2-Complex tongue thrust swallowing: = there is a contraction of the lips, mentalis, facial muscles and lack of contraction of the mandibular elevators. = the patient is suffering from naso-respiratory distress, the open bite of this type is more diffused than simple and difficult to define. = when examined the dental casts there is poor occlusal fit and instability of inter- cuspation because the inter-cuspal position is not repeatedly reinforce during swallowing. This type does not diminish by age. = it is possible to have a complex tongue thrust but no open bite if the tongue is positioned even a top of all teeth during swallow. = the patient attention must have brought to the problem and the difficult prognosis explained carefully at the start of treatment, the patient should know at the start of treatment that much responsibility for successful therapy lies with himself or herself. 3-Retained infantile swallowing: = persistence of infant type of swallow after present of permanent teeth, this patient demonstrates very strong contraction of lips and facial muscles. = tongue thrust strongly between the teeth anterior and posterior. = patient has inexpressive face, and facial muscles used for stabilizing the mandible during swallow. Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

16. 16 = patient has high difficulties in mastication, the patient occludes only on one molar in each quadrant. = patient restrict to the soft diet. = this type occurs due to defect on the transitional phase of swallowing from infant to adult swallow. = the prognosis for correction of this type of swallow is poor. Fortunately, the true retained infantile swallow is rare. N: B: the following clinical observation regarding improper swallowing habits is made by Atkinson: == Hold your hand on the chin of the patient while the patient in the act swallowing, if the jaw is opened during the act of swallowing, the supra-hyoid muscle will pull the body of the mandible downward, bending it just anterior to the angle of the jaw. == The abnormal swallowing habit should be detected and corrected early to facilitate normal development of the palate and dentition. In its early detection, it should correct immediately with mechanical appliance to limit the tongue into its proper position. Abnormal tongue posture = the continuous effect of abnormal tongue posture may produce more open bite than more obvious tongue thrust. = there are two forms of protracted tongue posture: endogenous and acquired = during the arrival of the teeth, the tongue normally changes its posture and come to rest inside the encircling dentition, some children have an inherent abnormal tongue posture persist lying between the incisors. The great majority of the endogenous protracted posture problem are not esthetics and there is stability of the incisor relationship even a mild open bite is seen. = the acquired protracted tongue posture is a simpler matter, since it usually results from chronic pharyngitis, tonsillitis or other naso-respiratory disturbance, sometimes the nasopharyngeal condition no larger exist but the tongue remain in a forward position. N: B: an adaptive tongue posture is sometimes seen when the maxilla is narrower than the mandible, since the tongue must aid in the encircling seal to complete the swallow. It may adapt a posture a top on the lower teeth, when rapid palatal expansion is completed and posterior inter- cuspation is correct, a normal posture usually return, posterior open bite are more often postural problems than lateral tongue thrust. Mouth breathing Definition: habitual respiration through the mouth instead of the nose. Recognition: to institute treatment of the actual cause, it is very important to determine the type and degree of mouth breathing. The habit can be habitual or obstructive. In mouth breathing, the patient is not aware of the habit which is present at night during sleep; mouth breathing may be total or partial, continuous or intermittent. Linder Aronson and Bushey discuss three hypotheses for mouth breathing: 1-Adenoid enlargement leads to mouth breathing, resulting in a particular type of facial form and dentition. 2-Enlarged adenoids may lead to mouth breathing and do not influence the facial form and type of dentition. 3-Enlarged adenoids in certain type of faces and dentition may lead to mouth breathing. Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

17. 17 Linder Aronson’s studies are the most detailed research in humans, his reports on the relationship between reduced respiratory function and facial type and dentition. He studied children who had undergone adenectomies to clear the nasal passage, the finding after 5 years from mouth breathing to nasal breathing are: == Normalization of upper incisors inclination. == Improvement of lower during first year. ==Return to normal bi-molar arch width. == Normal depth of the nasopharynex. ==Improvement in the mandibular plane and lower face height. ==Improvement in the head posture, which was altered prior to surgery. Patient with long term mouth breathing is characterized by: 1-Open mouth posture. 2-Short upper lip. 3-Tendency to open bite. 4-Nostrils are small and poorly developed. 5-Nose appears to be flattened. 6-Narrow and high palatal vault. 7-Posterior cross bite. These morphologic adaptations are believed to be result from alteration in activity of specific facial muscles related to mouth breathing. It was observed that children with open mouth posture displayed a significantly slower pattern of maxillary growth compared with children who displayed anterior lip seal posture. N:B: maxillary arch width was determined by placing a millimeter boly- gauge against the maxillary lingual cusp at the cemento-enamel junction of upper 1st molar and the other 1st molar on the other side. Mouth breathing in allergic children: Study was made in 45 Caucasian in both sexes age ranging from 6 to 12 years. Thirty is chronologically allergic mouth breathing and fifteen non-allergic mouth breathing and the study indicated that: 1-Anterior facial height is significantly larger in mouth breathing. 2-Angular measurements of Sella- Nasion to palatal, occlusal and mandibular plane were greater in mouth breather. 3- Gonial angle is larger than normal. 4-Over-jet is greater than normal. 5-Maxillary inter-molar width narrower than normal and also associated with posterior cross bite, all these features support that nasal airway obstruction is associated with defect in the facial growth. N:B: arch width is measured from mesio-buccal cusp tip from one side to the other side. Tongue sucking This habit can occur habitually or due to macro-glossia and its activity is similar to the thumb sucking and usually disappear about the 2nd year of life. Tongue sucking may cause posterior or anterior open bite. Bottle feeding The mass of the tissue taken into the mouth by the child nursing at the breast exerts spreading action on the jaws and aids in their normal growth. In addition, the tongue movement inside the mouth during breast feeding is ideal and so help in development of normal swallowing behavior. Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

18. 18 In the bottle of baby this spreading action may be absent, the milk from the bottle is follow by action of sucking that produce a negative pressure in the mouth which contract the cheeks and compress the jaws, and requires no further movement of the tongue so abnormal swallowing may develop. Lip sucking and lip biting Lip sucking may appear by itself or may be seen with thumb sucking, the lower lip is the most frequently involved and also the upper lip may be involved. This habits leads to: 1- labioversion of maxillary anterior teeth. 2- linguoversion of mandibular teeth. 3- Increased over-jet and over-bite. 4- Lip hypertrophy. The deformity reaches its maximum when the discrepancy between the maxillary and mandibular incisors becomes equal to the thickness of lower lip. Nail biting One of the most common habits in children and adults, it is a sign of internal tension. Absent under 3 years of age, there is a rapid increase at 6 years of age followed by sharp rise at puberty and followed by rapid decline after age of 16 in boys. After the age of 15 year, the nail biting is replaced by pencil biting, lip biting, nose picking, and hair twirling, or smoking in boys. Clinical nail biters show: 1- Crowding and rotation. 2- Attrition of incisal edge of incisors teeth especially the lower incisors. 3- Tendency to class III malocclusion. Pillowing habit Postural defect during sleep are considered as an etiologic factor in the development of malocclusion. The effect depends upon the frequency, duration and the amount of pressure exerted by the abnormal postures; also depend upon the resistance of the bone to deformation. Flattening of the skull and facial asymmetry may occasionally develop during the 1st years of life where the infant in supine position with the head turned to the right or left for longer time. The pillow of the child must be at the level of his shoulder and not too high or low, and the mother must change the position of her child at frequent intervals. Traumatic occlusion Force exerted upon the teeth are usually tolerated by supporting tissues when of normal limit, while excessive force created by such habits like bruxism may be more than the physiologic limit of the periodontal fibers and so there is a destruction of periodontal and alveolar support of the teeth may occurs 9-Postures Poor postural condition can cause malocclusion. 1- Chin propping habit: A chin propping habit (extrinsic pressure, unintentional) will cause a deep anterior closed bite, and may also cause the mandible to be retracted. Note that there is little of lower anterior teeth is visible when the jaws are in closed position. 2- Face leaning: Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

19. 19 Lateral pressure from face leaning (extrinsic pressure unintentional) may cause lingual movement of maxillary teeth on that side. The mandible being less affected because it does not have a rigid attachment and slide away from the pressure. 3- Head posture: Faulty head postures can cause abnormal changes in the form of jaw bones. Curvature of the neck and cervical spine causes forward and upward positioning of the head which is commonly associated with class II malocclusion. Robin suggested that child must held in an upright posture to prevent pressure on the face. 4- Mandibular postures: Low mandibular postures associated with mouth breathing initiate abnormal neuromuscular reflexes. That may be responsible for production of class II malocclusion and open bite. 5-lip posture The lip may be incompetent when the face in repose position this may be responsible for production of bi-maxillary protrusion or class II division 1 malocclusion 6-Tongue postures: = The normal tongue posture is important for the development of normal occlusion. The tongue posture over the occlusal surface of the teeth is responsible for open bite = lateral tongue thrust may produce open bite = in case of Bell’s palsy the tongue and lips are usually affected and its normal position is changed so the occlusion is changed if the condition is prolonged 10-Accident and trauma: = accidents are more significant factor in malocclusion, as the child is learn to crawl and walk, the face and dental arches are receiving trauma = traumatic displacement of deciduous incisors may affect the normal eruption of permanent successors = non-vital deciduous teeth have abnormal resorption pattern and as a result of initial accident they deflect the permanent successors = blow or trauma is responsible for ankylosis of teeth and the resultant malocclusion = ankylosis of TMJ early in life interfere with growth and normal tooth alignment = dental trauma can lead to malocclusion in three ways: 1-damage to permanent tooth buds from an injury to primary teeth 2-drift of permanent teeth after premature loss of primary teeth 3-direct injury to permanent teeth 11-Muscle Action The facial muscles can affect jaw growth in two ways: 1-the formation of bone at the point of muscles attachment depend on the activity of muscles 2-the musculature is an important part of total soft tissue matrix whose growth normally carries the jaws downward and forward muscle weakness: = found to be associated with underdevelopment of the mandible, strong muscle action is associated with strong well developed jaws but not necessarily always with good dental alignment = deep over bite may be caused by strong elevator muscles do not permit full eruption of buccal teeth, open bite may be associated in many cases with weak mandibular musculature Hyper active mentalis muscle: -cause flattening of mandibular anterior teeth segment and mandibular arch collapse -it is also cause protrusion of maxillary incisors due to lower lip trap during swallowing Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

20. 20 hypo-tonicity of upper lip: causes protrusion of maxillary teeth, it is commonly seen in class II division 1 malocclusion, on the other hand the hyper-tonic upper lip may causes retroclination of maxillary incisors which often seen in class II division 2 malocclusion progressive muscular dystrophy: progressive weakness of the muscles, that allow the mandible to drop downward away from the rest of facial skeleton that result is: -high anterior facial height -distortion of facial proportion and mandibular form -excessive eruption of posterior teeth -anterior open bite facial paralysis can also produce the same effects NB: Hypertrophied muscle: the tissues are hard, tense, rigid musculature that act upon the dental arches as restraining band prevent molding effect Hypotonic muscle: reduction in the normal tonicity of the muscle, the muscle is bulky Hypertrophy: actual increase in the amount of muscle substances, this condition is due to hyperactivity of the muscle Atrophy: degeneration of the muscle tissues due to lack of use: disuse. Muscle elasticity: the muscle returns to its exact original shape after being stretched Muscle contractility: ability of muscle to shorten its length under innervation impulse Although the elasticity of muscle influence contractility Isometric contraction: the muscle restraining the external force without any actual shortening, the strength is greater than the isotonic Isotonic contraction: there is actual shortening of muscle and has low strength Macroglossia: is a relative term since the absolute size is difficult to evaluate because it is relative to the size of the oral cavity, thus the Macroglossia of mongolism is normal in decreased oral cavity, but in case of acromegaly is a true enlargement of tongue. == in case of a glossia or Microglossia there is collapse of the dental arches lingually due to lack of medial support between == the number of cells in a given muscle is non-proliferative after birth, their size however is under environmental influences as nutrition and function == the lack of growth of muscles through paralysis is expressed by diminutive coronoid or gonial process and steep of the lower border of the mandible and open bite == hypertrophy of muscles as masseter or temporalis will lead to enlarged coronoid and gonial process that followed by deep bite 12-Radiation: Treatment with radiation in the mouth of infant tends to destroy the teeth and tooth germ of the treated side Eruption is normal but the affected teeth show shortened or absent root formation The crown of permanent teeth in the affected side are usually smaller. Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

21. 21 N: B: Muscles activity during swallowing: 1-the mandible is depressed probably by the action of the lateral pterygoid muscle, so this enlarge the space within the oral cavity and make possible negative pressure 2-there is a contraction of the muscles of lips to prevent air from rushing into the mouth and destroyed the vacuum, these muscles are: a-orbicularis oris b-triangularis c-canini d-mentalis which are narrowing the oral opening 3-the central fibers of buccinator muscle and the tissue of the cheeks are down between the occlusal surface of molars and premolars and canine by intra-oral vacuum, this: produce lingual pressure on the buccal segment of the arch 4-the tongue is withdrawn from contact with: a-lingual surface of maxillary and mandibular incisors b-mucous membrane of the hard palate the central section is depressed by the action of genioglossus the side is rolled upward by styloglossus muscle 5-the root of the tongue is elevated against the soft palate by contraction of suprahyoid muscle, styloglossus, platoglossus 6-muscles of soft palate are relaxed top come down and meet the raised root of the tongue and thus shut of the pharynx and permit the vacuum to be performed *** the thumb sucking lead to high negative pressure within the mouth with narrowing of the maxillary arch that upset the force the force system in and around the maxillary complex, so it often impossible to the nasal floor to drop vertically to the normal position during growth *** Tonsils: -Palatine tonsil -Lingual tonsil -Pharyngeal tonsil = tongue thrust can occurs due to enlarged tonsils (inflamed) Anterior pillar: attached to the base of tongue Posterior pillar: attached to wall of the pharynx = forward position of the mandible to relative the pressure from the enlarged tonsils ----- give ability to class III = tongue thrust during swallowing to make less painful position and this give a sequelae of the tongue thrust disorder *** Hypertrophy: actual increase in the amount of muscle substances this condition is due to hyperactivity of muscle *** normal swallowing: Teeth in centric relation Tip of the tongue is placed at posterior part of rugae area of palate Tongue pressure is exerted backward and upward Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

22. 22 Muscles of expression are at rest Muscles of mastication are used to bring the teeth in firm occlusion *** pressure posture habit: Most common of these habit is the placing hands beneath the cheek or resting the cheek on the forearm or bunched pillow during sleep This usually practiced on one side only, will produce unilateral or localized malocclusion Mechanism: The weight of head is transferred to the tissue of the maxillary region The structure of the mandible usually is unaffected because this bone is movable part and escapes pressure by sliding away from it, *** Tongue position: Tip of tongue is rest in the lingual fossa or at the cervices of mandibular incisors Dorsum of tongue touch the palate lightly The lateral side is related to the lingual cusps of the molar and premolars *** lip position: At rest the lips are usually touch lightly to give an oral seal when the mandible is in its postural position There is an inter-labial gap about 2 – 4 mm during rest position *** nasal septum attached posteriorly to the posterior cranial base and cranial base angle measured 130 degrees, so any change in this angle affect the direction of the nasal septum growth so it affect the direction of growth of the maxillary complex *** Premature loss of deciduous teeth: Occurs as a result of: 1-General factors: which cause early root resorption a-Hereditary b-Endocrine disturbances: hyper-pituitarism, hyperthyroidism c-Disease: hyperphophatasia 2-Local factors: In which premature loss is limited to single tooth or group of teeth a-Caries b-Periodontal disease c-Trauma d-Infection Premature loss due to hereditary or endocrinal factors is usually followed by general advance in the rate of maturation and so, followed by premature eruption of permanent teeth While premature loss due to local factors is usually followed by disturbance in occlusion, its severity can be predicted *** abnormal swallowing: Muscles of mastication are not used to bring teeth into occlusion Tongue is thrust forward and contact with the teeth Facial expression muscles are contract especially the mentalis muscle Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

23. 23 *** in case of conventional nipple feeding -It is only contact with the mucous membrane of lips -Due to poor design, the mouth is held open more widely and greater demand is made by the buccinator muscle -The peristaltic movement of the tongue and mandible is reduced, suckling become sucking With enlarged hole at the end of nipple, it must be noted that the abnormal swallowing habit may be prevented by the use of very short nipple with one small hole to give high similarity to the breast feeding B-Intrinsic or local factors 1-Anomalies in number of teeth: Supernumerary teeth: = occurs most commonly in maxilla near the midline, palatal to maxillary incisors = these teeth are usually conical in shape and occur most often singly but can occurs in pairs = may be fused to the right and left central incisors = it may be erupting in any area in the mouth and may be well formed that is difficult to determine which one is supernumerary = the permanent teeth may not erupt or deflect as a result of supernumerary teeth = supernumerary teeth may erupt toward the floor of the nose instead of toward the palate = supernumerary teeth lead to crowding that lead to positional and occlusal anomalies, speech interferences, caries of adjacent teeth and supernumerary teeth itself, malocclusion and dental arch a symmetry = types: mesiodens: (conical tooth) between maxillary central incisors Peridens: buccal to the arch Distomolars: distal to 3rd molar Paramolar: buccal or lingual to the molars Missing teeth: = congenital missing teeth are more frequent than supernumerary teeth = where the supernumerary teeth are usually found in the maxilla the missing teeth are frequent in both jaws The order of absence frequency is: Maxillary and mandibular third molars Maxillary lateral incisors Maxillary second premolars Mandibular second premolars = congenital missing is more frequent in permanent than deciduous, where maxillary lateral incisors are congenitally missing; the permanent canine may often erupt mesial to deciduous canine into the space of missing teeth NB: anodontia: total absence of teeth Oligodontia: congenital absence of number of teeth Hypodontia: absence of only few teeth As a general rule: if only few teeth are missing the absent teeth is almost the most distal one of any given type as: in molars: third molar -------- in premolars:2nd -------- in incisors: lateral -- --- - canine is rarely 2-Anomalies of tooth size: The size of the teeth is largely determined by hereditary, there is a great variation in teeth size even with the same individual Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

24. 24 a-Macrodontia: tooth size is large than normal that may cause crowding and poor esthetic b-Microdontia: abnormally small size teeth, which may be localized or generalized, the crown is short and there is spacing and loss of interproximal contact = the anomalies in tooth size is frequent in the mandibular premolar area and maxillary latera incisors (peg shaped lateral) c-Taurodontisme: rare enlargement of the crown of the teeth, occurs in deciduous or permanent dentition and characterized by short root than normal (not indicated for orthodontic treatment because of insufficient root formation) 3-Anomalies of tooth shape: a-Hutchison’s incisors: Johnathan Hutchison was the 1st described the syphilitic hypoplasia of maxillary central incisors, the shape of the tooth is screw driver with greater gingival mesiodistal dimension, with notching at the incisal edge b-Mulberry molar: the crown appears constricted occlusally and the molar show enamel hypoplasia c-Enamel hypoplasia: reduction of thickness of enamel, result of deficiency in formation of organic matrix d-Peg shaped lateral: result from disturbance during morpho-differentiation, the crown is narrow incisally resembling the cone e-Fusion: two tooth germs are fused to form larger tooth with two roots or single grooved root, it is more common in incisors f-Dilacerations: angulation or bending of the root of the root or crown as a result of trauma during root formation g-Mottled enamel: localized defect in enamel calcification due to hyperflurosis, presents as chalky white, brown or black dots on the surface of enamel h-Dens in dent: means tooth within tooth and caused by invagination of enamel organ into the dental papilla, thus produce small tooth with the future pulp = commonly occurs in maxillary lateral incisors in 2% of population = pulp undergo necrosis and pulpal lesion is frequent i-Germination: single tooth germ splitted to form two completely or partially separated crowns but usually with single root 4-Abnormal labial Frenum: = At birth the Frenum is attached to the alveolar ridge with fibers actually running into the labial inter dental papilla = As the teeth erupt and as the alveolar bone deposited the Frenum migrate superiorly to the alveolar ridge, the fiber may persist between the maxillary central incisors and may the V shaped inter-maxillary suture, attaching to the outer layer of the periosteum and connective tissue of the suture = This attachment may well interfere with the normal closure of the spacing that result into median diastema NB: spacing between the maxillary central incisors and the presence of the fibrous tissue attachment such as the labial Frenum provide an excellent “chicken and egg’’ routine for controversy. Which is came first. Causes of median diastema: 1-Physiologic spacing of central incisors until 10 years of age or until canine is erupt (ugly Duckling stage). 2-Familial pattern. 3-Abnormal small size of teeth in large jaws. Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

25. 25 4-Lateral incisors missing or peg shaped. 5-Median cyst. 6-Short upper lip with maxillary protrusion. 7-Presence of dense square shaped bone between maxillary central incisors. 8-Tongue or figure habits 9-Mesiodens. 10-Malposed lateral incisor 5-Premature loss of deciduous teeth: The deciduous teeth serve as space saver for the permanent teeth and also assist in maintaining the opposing teeth at the proper occlusal level as well as for mastication. = the anatomic and functional forces maintain a dynamic balance of the occlusion. The loss of teeth can upset this balance and the dentist must restore the occlusal harmony to prevent the damage of dentition. = the severity of malocclusion resulting from loss of deciduous teeth cannot predicted. 1-Premature loss of maxillary deciduous incisors: usually not followed by impaction of permanent incisors such interference may be attributed to presence of supernumerary teeth or other causes. Premature loss may follow by shifting and dental arch deviation, the space maintainer may be required to prevent lisping as well as for esthetic purpose. 2-Premature loss of deciduous mandibular incisors: followed by crowding of permanent incisors with corresponding crowding in maxillary incisors, deep overbite may have developed. 3-Deciduous canines: premature loss of upper canine followed by interfere with the eruption of permanent canine, canine may be impacted or blocked lingually or labially due to late eruption time of canine permit the incisors to adjust themselves and close the space by shifting. 4-1st deciduous molars: is rarely followed by impaction of the 1st premolars because of the comparatively early eruption of 1st premolars and also smaller in size than deciduous predecessor, furthermore the 2nd deciduous molars not shift mesialy because the long axis is vertical in direction == if premature loss occurs before eruption of 1st permanent molar, strong force will be exerted on 2nd deciduous molar during eruption of 1st permanent causing it to shift mesialy and close some of space. == if premature loss occurs during active eruption of lateral incisors, strong distal force will exert on the primary canine causing it to shift distally and close the space. 5-2nd deciduous molars: marked forward shifting of permanent 1st molars, eruption of 2nd premolars out of alignment = if the 2nd deciduous molar is extracted before eruption of 1st permanent molar the 1st molar will erupt mesialy closing much of space required for 2nd premolar and impacting frequently occurs = if the 2nd molars extracted after eruption of 1st molar the 1st permanent molar may show slight or severe mesial tilting depend on many factors; occlusion, muscle behavior, arch length deficiency Effect of loss of posterior primary teeth: 1-Collapse of lower anterior teeth and the center line may be shifted to the side of extraction. Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

26. 26 2-As a result of premature loss of both upper and lower 2nd molars pseudo mesio occlusion may occur as the child will protrude the mandible to bring the lower anterior part in contact with the upper 3-Crowding of mandibular incisors and deep bite 4-Forward shifting and mesial tilting of mandibular 1st molar with impaction or palatal eruption of 2nd premolars. 6-prolonged retention of teeth: Causes: 1-Incomplete or unequal resorption of roots 2-Absence of permanent teeth 3-Ankylosis of deciduous teeth 4-Abnormal path of eruption of permanent teeth 5-Endocrine disturbance as hypothyroidism 6-Nutritional disturbance Effects: 1-Deflection of permanent teeth bucally or lingually 2-Impaction of permanent teeth 3-Prolonged retention of deciduous incisor or canine usually results in the deflection of the permanent successor with disturbance of occlusion 4-If the prolonged retention of the deciduous molars is in the mandible only without maxilla, the tendency to mandibular protrusion may be initiated 7-Delayed eruption of permanent teeth: The retarded eruption of the permanent teeth can cause disturbance in the arrangement of teeth because of shifting of erupted teeth producing lack of space for on coming teeth, the unerupted tooth may be blocked labially, lingually or bucally or even impacted Causes: 1-Presence of supernumerary teeth 2-Trauma of tooth germ 3-Infection of tooth germ 4-Displacement of tooth germ by tooth or neoplasm 5-Ankylosis of the tooth with the jaw bone 6-Systemic disease such as endocrine disturbance 7-During premature loss of deciduous tooth, there is a chance for mucosal barrier, if eruptive force is not vigorous the mucosa can effectively stop the erupting tooth for considerable period of time. It is a good preventive measure in dentistry to excise the mucosa when the an erupted tooth appear ready. N:B: delayed eruption of central incisors upper: Leads to: 1- lateral incisor may move medially, encroaching the space which should be available for central incisors. 2-Reduction in the dento-alveolar development in vertical direction, with the result as the central incisor erupt remain in higher level than other teeth. 8-Abnormal eruptive path: It is considered as secondary manifestation of primary disturbance Causes: Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

27. 27 1-Severe crowding and totally in- adequate space to accommodate all of the teeth, so the deflection of the erupting tooth is response to that 2-Presence of supernumerary tooth, retained deciduous tooth or root fragment or bony barrier often influence the direction of eruption. 3-Trauma to the deciduous teeth may due to the development of successor in an abnormal direction 4-Mechanical interference by orthodontic treatment also can cause change in eruptive path. As early Class II therapy against the maxillary arch to move the maxillary dentition posteriorly can cause the second molars teeth to erupt into cross bite or can impact the developing third molar more deeply. 5-Coronal cyst can also cause abnormal eruptive paths. 6-Some abnormal eruptive paths are of unknown origin (idiopathic) 7-Ectopic eruption, that is generally considered a manifestation of arch length deficiency Effect: 1-Crowding and malposition 2-Impaction N:B: ectopic eruption of maxillary canine: Primary ectopism: due to disturbance in the long axis due to rotation of the tooth germ. Secondary ectopism: = due to lack of space in the arch and the canine is erupting in labial vestibules and may be in high position on the labial alveolar process = over retention of deciduous canines. 9-Ankylosis: Probably due to injury of some sort resulting in joining the lamina dura and cementum, it may occur in the buccal and lingual aspect and thus unrecognizable in the radiograph Clinically the ankylosed tooth appears submerged due to eruption of the other teeth Early recognition and extraction of ankylosed tooth is important to avoid malocclusion The permanent teeth may also ankylose as a result of: 1-Endocrine disturbance 2-Cleido-cranial dysostosis 3-Accident and trauma 4-Some ankylosis may occur with no apparent cause 5-Ankylosed deciduous should be extracted as soon as diagnosed to permit erupting of successor. 10-Dental caries: may lead to: 1-Premature loss of deciduous or permanent tooth 2-Subsequent drifting of the contiguous tooth 3-Abnormal axial inclination 4-Over eruption The caries tooth should be repaired not only to prevent infection and loss of teeth but to maintain the integrity of the dental arches 11-Impaction: Impacted tooth is that prevented from intra-oral emergences due to: 1-Lack of space 2-Over retention of deciduous tooth Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

28. 28 3-Presence of local interference 4-Abnormal eruptive path 5-Ankylosis Effects: 1-Resorption of adjacent tooth root 2-May cause cyst 3-Disturbance in occlusion when occurs in the front of 2nd molar 12-Improper dental restoration: Which is not contoured to the anatomical landmarks of the teeth, may lead to: 1-Poor inter proximal contact and shifting of the teeth 2-Over eruption of the teeth due to under filling 3-Traumatic occlusion due to premature contact 4-Food impaction and secondary caries 5-Periodontal disease 13-Loss of permanent teeth: Hershfield pointed out that: every individual tooth is an essential keystone not only for one arch but also for both arches, the removal of single tooth causes the active forces which tends to disarrange of dental arches. According to Hershefeld, the loss of single tooth may have the following sequela: 1-Break the continuity of dental arch, which lead to shifting of teeth mesiodistal or buccolingual and this leads to: food impaction, Traumatic occlusion, Root exposure, Periodontal pocket, interdental spacing. 2-Elongation of the teeth: has the following effects: a-Traumatic occlusion. b-Food impaction c-Root exposure d-Shifting e-Difficulties in restoration 3-Tooth shifting: tooth shifting after extraction is not predictable, the following are types of shifting of adjacent teeth can occur after extraction in mouths with normal occlusion: 1-Loss of central incisors produce mesial shifting of lateral incisors and this lead to spacing between lateral incisors and canine and mesial shifting of the canine. 2-Loss of lateral incisors produce distal shifting of the central incisors and mesial shifting of the canine. 3-Loss of canine produce distal shift of the incisors and rotation of the premolars. 4-Loss of 1st premolars usually results in: == distal shifting of the canine. == space between central and lateral incisors may present and mesial shifting of the teeth posterior to the 1st premolar and this followed by rotation. 5-Loss of 2nd premolars lead to distal shifting of 1st premolars and present of space between the canine and 1st premolars, and followed by mesial shifting of the molars, the 1st molars may show lingual inclination and loss of occlusal contact. 6-Loss of 1st molar produce: = distal shifting of the premolars = in maxilla, the premolars shift together and collapse of arches Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

29. 29 = in mandible, the premolars shift single which create space between them and also distal to canine, collapse of anterior segment with deep bite. = mesial shifting of the second and third molars = at the same time, there is flattening or narrowing of the maxillary dental arch 7-Loss of second molars, produce mesial inclination and shifting of the third molar 8-Loss of 3rd molar does not produce distal shifting of the second molar N: B: distal drift appears to has two sources: 1-Active contraction from the transeptal fibers in the gingiva 2-The pressure from the lips and checks Occlusal changes following extraction of 1st molars can be summarized as follow: 1-Without control of direction of shifting of the remaining teeth in the mouth is a factor to produce malocclusion 2-In case of Class I angle may change into Class II division 1 or 2 subdivision depend on the relation of the lips a-Slip under maxillary teeth ------ div 1 b-Not slip under maxillary teeth -----div 2 3-In case of Class II div 1: In maxilla: not result in self-correction because of small amount of distal shifting of premolars, and mesial shifting of adjacent second molars In mandible: = increase the relative protrusion of maxillary incisors = attending lingual collapse of mandibular incisors. 4-In case of Class III: In upper arch: increase the malocclusion In lower arch: not benefit because the tendency of lower premolars to shift singly and create interdental spacing 5-If 1st molar lost before 2nd molar erupt, there is a tendency for the 2nd molar to fall into the alveolus and erupt distally causing disturbed occlusal relationship. 14-Periodontal disease: = malocclusion that show significant relationship to periodontal infection include vertical incisor overbite. = malocclusion can be causative factor in periodontal disease = malocclusion can cause gingival trauma and it permit food particles to become impacted With my best wishes;;;;; Etiology of Malocclusion Etiology of Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby