• Congenital : Existing since before birth or at birth; dating from birth. Congenital malfor- mations are anatomical or structural abnor- malities that are present at birth, though they may not be diagnosed until later.• Hereditary: Transmitted from ancestors or parents to a child. Same as genetic.• Genetic : Transmitted from one generation to another through genes, same as hereditary.• Autosomal : A trait transmitted by a gene carried on an autosome ( any member of the 22 paired chromosomes other than the X and Y sex chromosomes ).
• Sex-liked: A trait transmitted by a gene carried on one of the sex chromosomes.• Dominant : A dominant gene is one which will produce its effect when present in either heterozygous or homozygous condition ( when only one or both alleles are affected ).• Recessive : A recessive gene is one which will produce its effect only when present in a homozygous condition ( only when both alleles are affected ).
• Developmental : Characterized by , or belonging to the process of development. Used here to designate a condition or disease caused by some non- hereditary error in the process of development.• Acquired : A term used to describe a condition, habit or other characteristic which is not present at birth , but which develop in the individual by reaction to some environmental factor ( to acquire is to obtain ).• Translocation : Transfer of chromosomal material between chromosomes. This involves breakage of both chromosomes with repair in an abnormal arrangement.• Inversion : This arises through two chromosomal breaks with inversion through 180 of the segment between the breaks.
• Deletion : This arises from loss of a portion of a chromosome between two break points or as a result of a parental translocation.• Teratogen : Any agent that can induce or increase the incidence of a congenital malformation. An agent capable of causing abnormal development prior to birth .
**According to the site:- (1)Anomilies of the jaws. (2)Anomilies of the palate. (3)Anomilies of the lips. (4)Anomilies of the gingivae. (5)Anomilies of the tongue. (6)Anomilies of the salivary glands. (7)Anomilies of the lines of fusion. (8)Anomilies of the teeth.
Agnathia• ** Very rare congenital defect.• ** it means complete absence of mandible or maxilla.• **it is more common in mandible (mandibular agnathia.).• **In maxilla:- the maxillary process or the premaxilla may be abscent.
Micrognathia** Means small arch either themaxilla or mandible.**It may be either:- #True micrognathia:- thatthe arch is really small insize.It may be congenital oracquired. #False micrognathia:- thatthere is abnormal postioningor relationship of one jaw tothe other or to the skull.
Pierre-Robin Syndrome• It is characterized by :-• **Hypoplasia of the mandible.• **Falling back of the tongue (glossoptosis) cyanosis & asphyxia.• **Frequently, an associated cleft palate & external ear defects.• **Associated bifid tongue may be present.• ** Other systemic findings as congenital heart defects, skeletal anomilies, occular lesions.• **Mental retardation may be found.
Macrognathia• The condition of abnormally large jaw.• It may be associated with:- **Some diseases of bone as Paget`s disease. **Hormonal disturbances as acromegally.
4- Torus mandibularis.• It is a common exostosis that develops along the lingual aspect of the mandible above the mylohyoid line in the region of the premolars.• Mostly it occurs bilateral, asymptomatic single nodules although multiple lobules are not uncommon.•• It appears to be more common in Asian and Eskimos.• On periapical radiographs, it shows as a radiopacity superimposed on the roots of the teeth.
1-Congenital lip pits• Congenital lip pits may occur in either upper or lower lip.• It affects more commonly the lower lip than the upper.• Lip pits are usually bilateral depressions on the vermillion border.• Lip pits, particularly those of the lower lip, are closely related to cleft lip and cleft palate.• The pits represent blind sinuses that descend through the orbicularis muscle to depth of 0.5 to 2.5 Cm and communicate with the underlying minor salivary glands.• They often extrude viscid saliva either spontaneously or upon pressure.
2- Congenital fistulae of the lips.• It is an extremely uncommon condition. It is characterized by two fistulae in the lower lip which present two orifices on the vermillion border, positioned one on each side of the midline.• The fistulous tract may be explored with a very fine probe and small amounts of mucous may be expressed.• The cause in unknown.
3-Commissural lip pits• These are an entity very closely related to lip pits, but occur at the lip commissures, appears as unilateral or bilateral pits at the corner of the mouth on the vermillion surface.• Treatment:• Surgical excision of these various pits has been recommended.•
5- Cheilitis glandularis apostematosa.• This is an uncommon condition of unknown etiology in which the lip becomes enlarged, firm and everted exposing the openings of the labial mucous glands.• The labial mucous glands become enlarged and nodular and the orifices of their ducts become inflammed and dilated giving the lateral mucosa a red macular appearance.•• The condition affects males much more commonly than females, and painless. Malignant transformation has been reported.
6- Cheilitis granulomatosa. Melkerson Rosenthal Syndrome• It includes Cheilitis granulomatosa, recurrent facial paralysis as well as a fissured tongue.• Cheilitis granulomatosa :-It is a disorder characterized by a chronic, rather firm swelling, affecting usually one lip but sometimes both.• Usually the upper lip is affected , occasionally the swelling affects the cheeks, fore head, chin or tongue.• Histopathology:• **a chronic inflammatory cell infiltrate.• ** There are scattered granulomata containing some epithelioid cells,• **few giant cells are sometimes also present.
Hereditary intestinal polyposis. (Peutz-Jeghers syndrome• This disease is a relatively rare and inherited as an autosomal dominant trait. It is of significance to the dentist because of its oral manifestation through which an early diagnosis can be established.•• Clinical features:• The melanin pigmentation of the lips and oral mucosa appears as small brown speckles measuring (1-5 mms) in diameter and mostly on buccal mucosa, gingivae, hard palate, neck, on the face the spots are grouped around the eyes, nostrils and lips.• The polyps are distributed through the entire intestine especially small intestine, are hamartomatous and are not premalignant, but may lead to serious intestinal obstruction and death.
Torus palatinus• **It appears as a single or multiple bony excrescences• **This is a developmental, frequently hereditary malformation about the midline of the palate.• **They are sometimes flat and fusiform and sometimes lobulated and nodular.• **The covering mucous membrane is intact but thin. Lesions are composed either of compact bone or a core of cancellous bone covered by a layer of compact bone.
4- Cleft lip and palate• Cleft:- is a defect which results from failure of fusion of any of the facial processes.• **The most common in the upper lip and palate region.• **Clefts are rare in the lower jaw.• **The incidence of cleft lip and palate varied in different parts of the world. It is generally taken to be about (1:800 – 1000) live births.• **Clefts are described as pre-alveolar (simple), alveolar and post-alveolar according to their occurrence in the lip, alveolus or palate respectively.• **The lesion may range from being:-• a simple notch of the lower border of the lip to---- -a broad cleft extending from the lower border of the lip to the floor of the nose.• **An accompanying cleft of the alveolus and
• Complete double clefts:- a portion of the lip (globular process) is isolated on the collumella.• This medial portion is small compared to the lateral elements of the lip, is devoid of muscle and shows no philtrum. Median clefts of the upper lip are rare, and as with lateral clefts, they vary in degree.• In the palate,• **Clefts extends forwards from the uvula and may involve the soft palate only or• The hard palate may also be involved to the incisive foramen, or• There may be a complete unilateral cleft extending from the uvula to the incisive foramen in the midline then deviating to one side and meeting the alveolar process in the area of the lateral incisor and then into the lip, or• there may be a complete bilateral clefts extending forwards bilaterally from the incisive foramen to the alveolus and lip. **Should the alveolus be bilaterally involved, the premaxilla remains suspended from the primitive nasal septum.
Complications of cleft lip and• palate• Infants are unable to suckle well and present feeding problems , they have a tendency to aspirate food and are therefore susceptible to respiratory diseases.• Infection of the nasopharynx which occasionally tracks up the pharyngotympanic tubes, leading to otitis media and deafness.• Older children have esthetics as well as social and psychological problems.• Defects in speech is being marked in the pronouncation of the letter K&G for the articulation of which the back of the tongue meets the soft plate.• TREATMENT:-** It is desirable to treat such individuals at an early age.• ** Clefts of the lip are usually treated by surgical closure in the first few months of life ,• ** Clefts of the palate at about 18 months of age.• **In some instances surgery is only partially successful and the cleft must be treated by prosthetic appliances.
DEVELOPMENTAL DISTURBANCES OFORAL MUCOSA & LINES OF FUSION
Fordyces spots or Fordyces granules.• Sebaceous glands are frequently included in the line of fusion between the maxillary and mandibular processes• Site:- *Are found just beneath the buccal mucosa along the line of occlusion of the teeth.• *They may be also seen opposite the last molar, around the parotid papillae and sometimes near the angle of mouth• *May also be seen on the exposed vermilion border of the lip as extensions from the skin beneath the lip mucosa• .Usually occur bilaterally• singularly or in groups as small (1-2mms) slightly elevated colored spots.• They produce a yellowish rough plaque.• . About 30% of the adult population have these inclusion.
White sponge nevus. White folded gingivostomatitis (• It is a congenital abnormality, yet it was suggested that it is a type of nevi on the basis that is limited to the buccal, rectal, and vaginal mucosa, and the upper part of the anal canal.• The mucosa appears thickened and folded with soft or spongy texture and peculiar white opalescent character.• Microscopically:• The epithelium is thickened but the basal layer is intact, there is intracellular edema of spinous cell layer. The cells of the spinous cell layer show pykontic nuclei and parakeratosis in the form of plaques. There is mild inflammatory cell infiltration of the submucosa.
Bohns nodules or (Epesteins pearls)• Rare small firm white or grayish white lesions may be seen on the palate or the alveolar mucosa of new born infants. They are usually multiple but do not increase in size.• Microscopically:• Reveal small superficial keratin containing cyst which are lined by stratified squamous epithelium and often spontaneously shed within four weeks, but it may be surgically removed.
Aglossia• ** A condition in which the tongue being completely absent at birth.• **when present is always accompanied by cleft palate.
MicroglossiaIs a rare congenital abnormallymanifested by the presence of asmall or rudimentary tongue.
Macroglossia• Means an enlarged tongue, may be either:-•• Congenital macroglossia is due to an over- development of the musculature.• Secondary macroglossia may occur due to• * Tumor of the tongue (lymphangioma or haemangioma).• * Neurofibromatosis.• * Malignant neoplasms- Blockage of the lymphatic vessels.• * Acromegaly due to hyperpituiterism in the adult.• *Cretinism or congenital hypothyroidism.• *Amyloidosis. is the deposition in the tissue of an abnormal protein with characteristic staining properties, it can result from over production of immunoglobulin light chains, usually by multiple myeloma.
Downs syndrome Downs syndrome is the most common clinically• recognizable syndrome with severe learning difficulty.• It is caused by trisomy of chromosome 21 giving a total• complement of 47 chromosomes instead of 46.• This is usually caused by failure of the chromosomes to separate during meiosis in the ovum, a defect closely linked to• maternal age.•• The overall incidence is 1 in 700 live births but the risk rises to 1 in 25 in mothers aged 45 years or over.•• Because the defect arises in the ovum, both parents are• normal and the condition is not inherited.• .
• In contrast, about 4% of Downs patients have the additional chromosomes 21 genetic material translocated to another chromosome.• The translocation is transmitted in a familial pattern but the parents are normal and the risk of an affectedchild is relatively low. In rare cases of mosaic Downs syndrome the trisomy arises during early development and the patients are a mosaic of cells with and without trisomy 21.• In this type of Downs syndrome the features are very variable and intelligence may be normal despite the typical appearance.
• General features:-• Class III malocclusion with hypoplastic maxilla.• Protrusive, fissured and enlarged tongue.• Everted, thick, dry and crusted lips.• Oligodontia.• Delayed eruption of teeth.• Hypoplastic dental defects and short roots.• Low caries activity.• Gross plaque accumulation.• Rapidly progressive periodontal disease.
• Bruxism.• Cleft palate in a minority.• Short stature with short limbs.• Poor muscle tone.• Generalized susceptibility to infection.• Cardiac anomalies in 40% .• Susceptibility to leukaemia.• Alzheimer-like dementia in later life.• Macroglossia of either type may produce displacement of teeth and malocclusion because of the muscles involved and• The pressure exerted by the tongue on the teeth
5- Cleft tongue• A completely cleft or bifid tongue is a rare• It results from lack of fusion of the lateral halves of this organ.• A partially cleft tongue is manifested as a deep groove in the midline of the dorsal surface
6- Fissured tongue (Scrotal tongue)• It is a malformation manifested clinically by numerous small furrows or grooves on the dorsal surface often radiating out from a central groove along the midline of the tongue.• Is usually asymptomatic• Although some patients may complain of mild burning soreness.
7- Hairy tongue• is not specifically a developmental disturbance• it is characterized by hypertrophy of the filiform papillae of the tongue with lack of normal desquamation and form a thick matted layer on the dorsal surface• The color may vary from yellowish white to brown or even black depending upon their staining
Median rhomboid glossitis• This congenital abnormality of the tongue is due to failure of the tuberculum impar to retract before fusion of the lateral halves of the tongue.• Clinically• * An ovoid or rhomboid- shaped reddish patch on the dorsal surface of tongue• *Immediately anterior to the circumvallate papillae.• *It is a flat or slightly raised area and has no filiform papillae.
Geographic tongue (benign migratory glossitis)• It consists usually of multiple areas of desquamation of the filiform papillae of the tongue in an irregular circinate pattern.• The central portion :-sometimes appears inflamed• the border:-may be outlined by a thin yellowish line or band.• The areas of desquamation remain for a short time on one location and then heal appears in another location.• It may persist for weeks or months and then regress spontaneously, only to recur at a later date.
Lingual thyroid nodule:• It is an anomalous condition in which follicles of thyroid tissue are found in the substance of the tongue possibly• Arising from a thyroid anlage which failed to migrate to its position.• Clinically:• * It appears early in life chiefly during puberty and adolescence.• It appears as a nodular mass in or near the base of the tongue in the general vicinity of the foramen caecum,• most often at the midline.
Ankyloglossia• Complete ankyloglossia :- occurs as a result of fusion between the tongue and the floor of the mouth• Partial anykloglossia or tongue tie usually resulting of:-• ** a short lingual frenum• **or one which is attached too near the tip of the tongue• , The patients suffer from speech difficulties.
Elephantiasis Gingivae (Congenital Macrogingivae )• A diffuse fibrous over-growth of the gingival tissues.• It is a hereditary condition being transmitted through a dominant autosomal gene.• Clinically: *young children usually appearing about the time of eruption of the permanent incisors. *dense diffuse, smooth or nodular overgrowth of the gingival tissues of one or both arches. *normal or pale color.• Microscopically: it is similar to any fibrous hyperplasia. The epithelium may be thickened with elongated rete processes, although the bulk of the tissue is composed of dense fibrous connective tissue and bundles of collagen fibers which are coarse.
DevelopmentalDisturbances of the salivary glands
Aplasia •• **This means complete absence of one or more of the salivary glands.•• **It results from failure of the terminal cells of a developing gland to differentiate.•• **No hereditary basis has been reported.•• **The condition is not necessarily associated with other congenital malformation.• **If the remaining salivary glands can not compensate the deficiency in salivary secretion caused by the aplastic gland, dryness of the mouth, (xerostomia).
Atresia• A condition in which there is congenital absence or occlusion of one or more of the ducts of major salivary glands.• It may result from degeneration or failure of canalization of the more proximal part of the epithelial salivary gland analage after the distal part has differentiated into salivary tissue.
Aberrancy• This is a condition in which normal secreting salivary gland tissue develops at an abnormal position ( Ectopic ).• It has no clinical or pathological significance apart from the fact that the aberrant tissue may be the site of development of a cyst or neoplasms.
Latent bone cyst• This is also known as developmental lingual mandibular salivary gland inclusion cyst or depression.• In this condition, a part of the submandibular, or more rarely the sublingual gland may develop in bony cavity or depression in the lingual surface of the body of the mandible, maintaining, however, its connection with its parent gland.• The condition is usually discovered ancidentally on radiographic examination, and appears as an elliptical or rounded radiolucent area most often situated in the molar region slightly above the lower border of the mandible, between it and the inferior alveolar canal.• Latent bone cyst should be differentiated from traumatic bone cyst which almost lies above the mandibular canal on the radiographic picture.
Anodontia• 1-Total anodontia :• **Complete developmental absence of the teeth.• **very rare ,mostly it is associated with ectodermal dysplasia.• **It is of genetic origin . **males are more affected. **It is due to aplasia of the dental lamina, **if the permanent teeth are only missing this means that further development has been stopped after giving the enamel organ of the milk set.
2- Partial anodontia:- •• **Not so rare as total anodontia.• **It means developmental absence of one or more teeth have never been developed, the common to be are maxillary laterals, lower premolars, and third mo• **missing teeth in the arch. may have developed but failed to erupt ( detect by radiograph) :- .(1) cleidocranial dysostosis, (2) teeth may have been extracted after or before eruption as in the case of premolars and molars. (3)Also in irradiated jaws, we may have missing teeth if irradiate.
Additional teeth• 1- Predeciduous Dentition.• **Infants occasionally are born with hornified epithelial structures without roots which appear to be erupted teeth on the gingiva over the crest of the ridge, which may be easily removed.• **Natal teeth:- which may erupted by the time of birth.• **Origin:-• (1)from an accessory bud of the dental lamina ahead of the deciduous bud• (2)or from the bud of an accessory dental lamina.
• 2- Postpermanent teeth or tooth ( dentition ).• Most of them are the result of delayed eruption of retained or embedded teeth.• A small number of cases, do appear to represent examples of a postpermanent or third dentition,• They are concidered as multiple unerupted supernumerary teeth.• They probably develop from a bud of the dental lamina beyond the permanent tooth germ.
3-Supernumerary teeth •• Are teeth in excess of the normal complement• . the pathogenesis:-• * Black ( 1909 ) suggested that supernumerary teeth are developed from the whorls of epithelial cells which are left after the dental lamina disintegrates.• *hyperactivity of the dental lamina and its downward growth from the oral epithelium.• *a division of the tooth germ.
• . Mesiodense. This is the common variety, and it can occur singly or in pairs between the central incisor teeth. It is usually rudimentary and peg- shaped.•• well-formed supernumerary tooth found between the central and lateral incisor, or between the lateral incisor and canine. Supernumerary teeth in the mandibular incisor region are usually normal in size and form.• . They are most commonly founded in the anterior region of the maxilla.• . It may be retained as an impacted tooth ,preventing the eruption or proper placement of the adjacent tooth.
Megadontia & microdontia• Macrodontia:- Large teeth.• Microdontia:- Small teeth• The whole dentition or only one tooth may be affected.• There are racial differences in the size of the teeth.• Teeth may appear large or small in relation to the jaw size (False micro or macrodontia)• Causes of large and small teeth :• 1- Hereditary.• 2- Racial.• 3- Pituitary. Hyperpituitarism results in large teeth,• hypopituitarism results in small teeth.
Gardners Syndrome:• It is characterized by the occurrence of multiple impacted supernumerary teeth. This syndrome consists of :• 1- Multiple polyposis of large intestine, polyposis coli with a high malignant potential. The intestinal polyosis in this• condition are permalignant.• Early recognition of these oral features should promot bowel radiography or endoscopy and possible prophylactic colectomy ( life - saving. )
• 2- Osteomas of the bones ( long bone- skull-jaw )• 3- Multiple epidermoid or sebaceous cysts of the skin, particularly on the scalp and back.• 4- Desmoid tumors. (Skin tumors)• 5- Impacted supernumerary and permanent teeth.• It is due to a single pleiotropic gene and has an autosomal dominant pattern of inheritance, with complete penetration and variable expression.
Histo-morpho differentiationstag( variation in size & shape ).
Dilaceration• An angulation, or sharp bend or curve, in the root or crown of a formed tooth. The condition is though to be due to trauma during the period in which the tooth is forming.
Dens in dente• Dental anomaly which can occur in the crown or root of a tooth ..• The condition is, rather, an enamel organ invagination of variable degree, for which reason, ( Oehlers, 1957 ) has proposed the more logical and descriptive name, " dens invaginatous "• The coronal type :-enamel organ invagination during the developmental period of the tooth, it occur by projection of that invagination into the dentine papilla. The result is an enamel-lined central cavity with a small external opening.• The radicular type. :-proliferation of the epithelial cells causing an apical ingrowth into dentine and the result is a radicular invagination limited by cementum.• permanent upper lateral incisors. are the most affected teeth
Gemination• ** An abnormally shaped tooth appears as two teeth joined together into one tooth.• ** Partial division of single enamel organ results in the development of two conjoined teeth.• **The two components of such teeth may be equal size, or one of them may be distinctly larger than the other• ** Both components, however, share a single root canal and have one root. The union involves enamel, dentine and cementum.
Fusion• Fused teeth arise through union of two normally separated teeth germs.• Depending upon the stage of development of the teeth at time of the union.• Fusion may be either complete or incomplete.• The dentine is always confluent in cases of true fusion.• Also fusion may occur between a normal tooth and a supernumerary tooth.
Concrescence• **It is a form of fusion which occurs after root formation has been completed.• **The teeth are united by cementum only.• ** It is thought to arise as a result of• traumatic injury or crowding of teeth with resorption of the interdental bone• ** Concrescence may occur between more than two teeth,).
Taurodontism• Are a peculiar dental anomaly in which the body of the tooth is enlarged on the expense of the roots.• Common anomaly of the second and third molar, first molars are rarely involved.• Hammer ( 1964 ) suggested that the tourodontism is caused by failure of Hertwigs epithelial sheath to invaginated at the proper horizontal level.• In tourodontism the pulp chamber is reached to bifurcated or trifurcated region.
• The development of normal enamel occurs in three stages:• 1- The formative stage: during which there is deposition of the organic matrix. 2-The calcification stage: during which this matrix is mineralized. – 3- The maturation stage: during which crystallites enlarge and mature.
Amelogenesis Imperfecta Hereditary Enamel Dysplasia (• three types of amelogenesis imperfecta are recognized.• 1- Hypoplastic type: in which there is defective formation of• matrix• 2- The hypocalcification: in which there is defective• mineralization of the formed matrix.• 3- The hypomaturation: in which enamel crystallites remain• immature .
( Streeters syndrome ).• Hereditary Ectodermal Dysplasia:• Absence or very thin patchy hair.• Defects in the nails.• Absence of sweat glands.• Dry skin, failure to sweat.• The patient likes cold weather and in summer likes to sit in a cold bath.• There is also depressed nasal bridge and the alveolar process is deficient in height.
ENAMEL HYPOPLASIA .• Developmental disturbances of the structures of teeth may be hereditary or acquired, involving enamel , dentine or both.• I- Hereditary amelogenesis imperfecta.• II- Environmental (acquired) amelogenesis imperfecta.• Environmental hypoplasia• Defined as an incomplete or defective formation of organic enamel matrix of teeth.• In the enviromental ( acquired ) type, the cause may be a local factor that usually affects individual teeth, or it may be a general systemic factor affecting all the teeth undergoing development at the time of the disturbance.• 1-Local factors:• a- Trauma.• b- Infection.• c- Irradiation.
The following criteria are useful in differentiating hereditary , and enviromental enamel hypoplasia:-• 1-Hereditary anomalies usually affect both deciduous and• permanent dentitions, while enviromental factors result in• only one dentition, or even single tooth or teeth being• affected.• 2- Hereditary anomalies usually affect either enamel or dentine,• where as enviromental factors affects both enamel dentine.• 3-Hereditary hypoplasia usually produce diffuse or vertically• wrinkles or grooves where as enviromental hypoplasia• appear horizontally grooves.
H.E.HYPOPLASIA H.E.HYPOCALCIFICATIONNature of defect Quantitative QualitativeAmount of matrix Deficient NormalMaturation Normal DefectiveMineralization Normal DeficientHardness Normal DecreasedSurface texture Smooth in Rough unpitted areasLuster Translucent OpaqueAcid solubility Acid soluble Acid insolubleX-ray appearance Normal Decreased radioopacity Radioopacity enamel indistinguishable from dentineMicroscopic appearance Loss of prismatic structure Prismatic structure maintained
• Hereditary Enamel hypocalcification:• Here the amount or thickness of enamel matrix formed is normal and the defect is failure in its normal maturation and mineralization.• As a result of the failure in mineralization, the enamel will be soft to the probe and will lack its surface luster or gloss, having instead an opaque matt surface.• Microscopically, the prismatic structure of enamel is maintained, but a surface layer of laminated material is initially present, but becomes quickly worn out through attrition.
• Acquired Enamel Hypoplasia: (Enviromental)• **Except in cases of endemic flourosis, acquired defects of enamel are usually confined to the permanent dentition.• **Metabolic disturbances and infections severe enough to affect the structure of developing teeth will usually give rise to abortion when they occur at such an early stage of foetal life as to affect the developing deciduous teeth.• **Acquired enamel hypoplasia of the permanent teeth may be due to either local or systemic factor.• 1-Local factors:• a- Trauma:• ***Traumatic injuries to upper deciduous incisors, especially the central incisors, being the most exposed teeth, may push them deeply into their sockets resulting in their roots impinging upon the developing tooth germs of their permanent successors. Apart from the possibility of giving rise to dilacerations, as mentioned above, the trauma may lead to horizontally oriented hypoplastic defects running between the previously calcified enamel and that which is yet to be calcified at the time of trauma.
• b- Infection:• Periapical infection of a deciduous tooth, usually one of the molars, may reach the underlying developing tooth germ of one succeeding premolar and give rise to enamel hypoplasia of that tooth. The enamel of the affected tooth may be thin, irregular or may be entirely missing over an area of the crown. Severe infections such as osteomyelitis of the mandible may also affect the structure of dentine as well as enamel, or may even completely arrest both enamel and dentine formation resulting in stunted teeth.• 2- Systemic Factors:• Enamel hypoplasia may occur as a result of a number of systemic factors. The direct cause may either be:-• (1) Deficiency in mineral supply, or• (2) Toxic damage to the ameloblasts actively engaged in enamel formation at the time.• The hypoplasia usually presents itself clinically as one or more horizontally oriented rows of pits or depressions on the enamel surface. The enamel may be nearly normal in color and translucency or it may be opaque or stained.
• d- Fluorosis or Mottled Enamel:•• People who grow up in areas where the water supply contains large amounts of fluorides, usually 1.5 ppm. or more frequently exhibit signs of mottling of the enamel of their permanent teeth, the deciduous dentition being very rarely affected.• The incidence and severity of mottling increase with the increase in the fluoride content of the drinking water , and in areas where the fluoride content reaches or exceeds 4.5 ppm., nearly all the inhabitants will suffer from some degree of enamel mottling which is often severe, such teeth, however, show increased resistance to dental caries.• Clinically, mottling ranges from being• (1) very mild where small areas of the enamel surfaces exhibit white patches that may be slightly opaque or the enamel surface or chalky or may retain a fine surface gloss, to• (2) more severe forms where the enamel surfaces shows larger areas of mottling when the surface will be dull or even pitted, the enamel may be brittle and easily chipped away, and may even acquire after eruption a stain ranging from yellowish to brown or black.
• There is considerable individual variation in the effects of fluorosis upon different people. Some patients may suffer from mild mottling after exposed to relatively low concentrations of fluorides, while others exposed to higher concentrations may be completely free or may only suffer from a mild degree of mottling.• Mottling effects may be graded as follows:• 1- Very mild: small opaque areas involving less than 25% of• the surface area of the tooth.• 2- Mild : opaque areas involving more than 25% but not• exceeding 50% of the surface area of the tooth.• 3- Moderate: the whole of the enamel surface may be affected• with chalky white areas or yellowish or brown staining. The• enamel may become easily worn away.• 4- Severe: the enamel is grossly defective, opaque, pitted,• stained brown or black and is brittle
• e- Congenital syphilis:• Children born to syphilitic mothers show characteristic abnormalities in the size, shape and structure of some of their permanent teeth. These changes are so constant that they have become called the dental stigmata of congenital syphilis. The deciduous dentition of such children is normal as it develops at such an early stage of intra-uterine life that abortion results if the expectant mother contracts the disease at that stage of her pregnancy.• The upper first permanent incisors, and the first molars of both jaws are almost consistently affected in congenital syphilis. Sometimes, the maxillary lateral incisors or canines may also be affected.• Congenital syphilis is transmitted to the off spring only by an infected mother and is not inherited.• Reported by pathognomonic of the disease is the occurrence of Hutchinsons triad :-hypoplasia of the incisor and molar teeth, eighth nerve deafness and interstitial keratitis.
• HUTCHINSONS TEETH.• The characteristic upper permanent central incisors of congenital syphilis are known as Hutchinsons teeth.• They are barrel-shaped teeth whose mesial and distal surfaces converge towards each other in the incisal half, the mesial and distal incisal angles are rounded-off especially the mesial, they are notched in the middle of the the incisal edge• MOONS AND MULBERRY MOLARS:• The first permanent molars of congenitally syphilitic patients may be dome-shaped (Moons molars ), or their occlusal surfaces may be rough, pitted exhibiting multiple irregular tubercles replacing their normal cuspal pattern (Mulberry molars• The enamel of such teeth is hypoplastic, or it may be entirely lacking over certain areas of the crown surfaces; and the dentine too is often hypoplastic. It has been shown that the cause of these defects is perivascular oedema and infiltration of the developing tooth follicles causing the ameloblastic layer of cells to proliferate and bulge into the dentine papilla causing the described typical deformities.
DENTINOGENSIS IMPERFECTA.• Hereditary brown opalescent dentine:• This is a better term than dentinogenesis imperfecta.•• This is due to inherited dominant gene, and affecting all the teeth of both dentitions. In most cases 50% of the children are affected.• When it occurs together with bone disorders it is called osteogenesis imperfecta.• The teeth are small with bulbous crowns, constricted neck, short roots are somewhat translucent on eruption and later become gradually gray or brown with bluish reflection from the enamel , the teeth wear away quickly, disorder is mainly in the formation of the dentine but the enamel is often poorly calcified and tends to break and become lost easily in some cases.
• The dentine at the A.D.J is usually normal but that lying deeply shows disordered structure with a diminished number of tubules, poor calcification, imperfect formation of collagenous matrix and marked irregular incremental lines.• The pulp cavity becomes obliterated early and there may be numerous pulp stones.• In the dentine the tubules are irregular in size and in their shape.• In the deciduous dentition the pulp cavity is not completely obliterated light like chalk.• When first erupts it is normal and then suffers from attrition being soft and poorly calcified, acid insoluble and the matrix is left after decalcification after eruption it gets discovered brown and chips easily, rod pattern is normal, interprismatic substance is wider and clearly defined, and the transverse striations are well marked.• Enamel is not clearly differentiated from dentine radiographically due to this deficient calcification and the normal white cap of enamel over the dentine is not seen.
SHELL TEETH.• This is a rare variant of dentinogenesis imperfecta transmitted through the same gene.• Instead of dentine formation, though defective, continuing till it almost completely obliterates the pulp chamber as is the case in dentinogenesis imperfecta, further dentine formation completely ceases leaving a very large pulp chamber surrounded by a thin shell of dentine, and a normal layer of enamel.• Ground sections show enamel of normal appearance lying on a very layer of tubular dentine and irregular calcified material. Decalcified sections show a thin peripheral layer of dentine of normal appearance, at the deeper parts of which the tubules become dilated and abruptly disappear.•• Deep to this, a thin layer of irregular dentine matrix surrounds a normal pulp chamber containing coarse collagen fibers and no odontoblasts.