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80Eruption Hematoma83Eruption Sequestrum86Ectopic Eruption 94Natal and Neonatal Teeth5

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54Shedding of TeethOsteoclast/bone remodelingOdontoclast (cementoclast; dentinoclast)Resorption of soft tissues

Pressure from successional teeth

OdontoclastFigure Source: Dr. Sandra Meyers8PULPAL CONSTRICTION THEORYPERIODONTAL LIGAMENT CONTRACTION THEORYRESORPTION OF THE ALVEOLAR CRESTHORMONAL THEORYFOREIGN BODY THEORYBack to main page67Molecular Determinants of Tooth EruptionA review article by Wise et al (2002) stated that tooth eruption is a complex and tightly regulated process.Mononuclear cells (Osteoclast precursors) must be recruited into the dental follicle prior to onset of eruption. Recruitment may require colony stimulating factor 1 and monocyte chemotactic protein 1Parathyroid hormone related protein and interleukin 1 produced in the stellate reticulum are also involved in the signalling pathway

70Teething and teething difficultiesAccording to Macknin et al the teething period was defined as the 8-day period beginning 4days before a tooth emergence and extending 3days after the event.Over half of babies have one or more problems during teething.In a prospective study by Seward, mothers of 224infants reported 74% and 100% to suffer at least one local disturbance during the eruption of the front and back teeth, respectively.In the past, a variety of physical disturbances such as croup, diarrhea, fever, convulsions, primary herpetic gingivo-stomatitis, and even death have been incorrectly attributed to eruption. Many of these are common in early childhood, and there is no evidence to support an association with dental eruption . It is now accepted that the localized symptoms of teething vary between individuals, however, severe systemic upsets are unrelated to teething .

74Reassurance of the parents regarding teething signs and symptoms by the pediatrician, dentist or auxiliary staff is necessary. Steward recommended a sequential approach to the management of teething ranging from giving the child objects to bite on through topical and systemic medications. Biting on these chilled objects may give some relief from soreness by the pressure of biting, or hasten the eruption process. Hard vegetables such as chilled carrots or celery may be used. Teething rusks or biscuit preparations are available, consisting mainly of flour or fat. Care should be taken that these do not contain sugar or sweetening

Management of Teething124.Bone remodellingThe selective resorption and formation of bone surrounding the tooth cause its movement.

This theory also explains the tooth movement during pre-eruptive phase.

Bone formation also occurs apical to the developing tooth

135. Dental FollicleThere is signalling between the reduced enamel epithelium and the dental follicle.

This signalling regulates the timing of eruption of teeth known as biologic clock.

By providing a signal and chemo attractant for osteoclasts, it is possible that the dental follicle can initiate bone remodeling which goes with tooth eruption.

Teeth eruption is delayed or absent in animal models and human diseases that cause a defect in osteoclasts differentiation.

146. Periodontal ligamentThe remodelling of PDL has also been considered as a factor for tooth eruption.

The fibroblasts possess traction power that causes tooth movement.

The PDL helps lift the tooth to its occlusal plane during the supraosseous phase of eruption

Force theory RootPDLBone15167. Force theory / Pressure from Muscular ActionBerten suggested that the action of the musculature of the cheeks and lips upon the alveolar process might serve to squeeze the crown of the tooth out into the oral cavity like a pumpkin seed from between the fingers178. Hydrostatic PressureA number of studies exist to demonstrate that there is a hydrostatic pressure difference between the tissue around the erupting crown and its apical extent

The hydrostatic theory was investigated by Hassel and McMinn (1972) who demonstrated that the tissue pressure apically was greater than occlusally theoretically generating an eruptive force.

No association was found between the rate of eruption and the pressure gradient.

Modification of the pressure changed the rate of eruption in rabbits which somewhat supported the theory. 18

199. PULPAL CONSTRICTION

This theory states that the growth of the root dentin and the subsequent constriction of the pulp may cause sufficient pressure to move the tooth occlusally.

Evidence for the theory- The pulp is progressively constricted by growth of root dentin

Evidence against the theory - Pulpless teeth erupts at the same rate as the normal teeth, premolar will often jump into occlusion after the premature extraction of the deciduous molar without any appreciable growth of dentine or pulpal constriction.2010. PERIODONTAL LIGAMENT CONTRACTION THEORYSuggests that the contractile element within the periodontal ligament, collagen constriction due to fibroblasts are responsible.

Evidence to this theory - The actual force required to move the tooth is linked to the contractility of fibroblasts. When fibroblasts are plated onto silicone rubber, they crawl about and doing so create wrinkles or folds in the rubber indicating that tractions forces are associated with locomotion.

2111. RESORPTION OF ALVEOLAR CREST THEORYResorption of the alveolar crest would serve to expose the crown of the tooth into the oral cavity. This theory is not tenable since histological examination shows that the alveolar crest is the site of the most rapid and continuous growth of bone.2212. HORMONAL THEORYSir Arthur Keith suggested that the hormones secreted by the thyroids and pituitary glands might govern the eruption of the teeth. This theory does not attempt to explain the mechanism of the eruption of the teeth, and only points out the fact the hormones may affect the eruption of the teeth.

2313. FOREIGN BODY THEORYGottliebs foreign body theory, states that a calcified body such as the tooth tends to be exfoliated by the tissues just as does any foreign body.

26Back to main page29Permanent molars have no predecessors

Maxillary molars develop within the maxillary tuberosity with their occlusal surfaces slanted distally

Mandibular molars develop in the ramus with the occlusal surfaces slanting mesially

30Pre-eruptive tooth movement: Why do developing crownsmove constantly in the jaws during the pre-eruptive phase?

To place teeth in position for eruptive tooth movement

To alleviate the problems of jaw growth which allows second molar to move backward and anterior teeth to move forward

Developing crown move constantly during the pre-eruptive phase as they respond to positional changes of the neighboring crowns and to changes in the mandible and maxilla

Permanent teeth develop lingual to the incisal level of the primary anterior teeth and later as primary teeth erupt, the permanent crowns are lingual to the apical 3rd of primary roots

Permanent premolars move from occlusal level of primary molars to a position enclosed within the primary tooth roots

All movements in the preruptive phase occur within the crypts of the developing crowns 31Two types of tooth movement in pre-eruptive phase:

Total bodily movement

Movement where one part remains fixed while the restcontinues to grow leading to change in the center of thetooth germ32

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Figure from Ten Cates Oral Histology, Ed., Antonio Nanci, 6th edition36Eruptive Tooth Movement

4 major events occur:Root formation. Space is required for root formation Proliferation of epithelial root sheathInitiation of root dentin and pulpIncrease in fibrous tissue of the follicleMovement. Occurs incisally or occlusallyThe main reason for movement is so that theroots can form normallyReduced enamel epithelium fuses and contactsthe oral epitheliumPenetration of the tooths crown tip through the fusedepithelial layers allowing entrance of the crown into theoral cavity

Intraoral incisal or occlusal movement of the erupting toothcontinues until clinical contact with the opposing crown occurs37

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Essentials of Oral Histology and Embryology. James Avery, 2nd edition40

Essentials of Oral Histology and Embryology. James Avery, 2nd edition41Clinical crown: During eruption, the exposed crown extendingfrom the cusp tip to the area of the gingival attachment

Anatomic crown: Entire crown, extending from cusp tip to thecementoenamel (CE) junction42Histology changes that occur in tissues overlying erupting teethDegeneration of connective tissue (decrease in blood vessels and degeneration of nerves) immediately overlying the erupting teeth

Eruption pathway altered tissue area overlying the teeth

Macrophages destroy cells and fibers by secreting hydrolytic enzymes

Gubernacular cord: The connective tissue overlying a successional tooth that connects with the lamina propria of the oral mucosa by means of a strand of fibrous connective tissue that contains remnants of dental lamina

Gubernacular canal: Holes noted in a dry skull noted lingual to primary teeth in jaws that represent openings of Gubernacular cord

As the successional teeth erupt, Gubernacular canal widens enabling tooth to erupt 43

Essentials of Oral Histology and Embryology. James Avery,2nd editionFigure from Ten Cates Oral Histology, Ed., Antonio Nanci,6th edition44

Essentials of Oral Histology and Embryology. James Avery, 2nd edition45

Figure from Ten Cates Oral Histology, Ed., Antonio Nanci, 6th edition46Stages of tooth eruption

Essentials of Oral Histology and Embryology. James Avery, 2nd edition

47Histology Surrounding tissuesThe surrounding fibers change from being parallel to the tooth surface to bundles that are attached to the tooth surface and extending towards the periodontium (bone)

The periodontal ligament have contractile properties and changes drastically during eruption

During eruption, collagen fiber formation and turnover are rapid enabling fibers to attach and release and attach in rapid succession.

Some fibers may attach and reattach later while the tooth moves occlusally as new bone forms around it and the fibers will organize and increase in number and density as the tooth erupts 48

Essentials of Oral Histology and Embryology. James Avery, 2nd edition49

Essentials of Oral Histology and Embryology. James Avery, 2nd edition50The rate of tooth eruption depends on the phase of movement

Intraosseous phase: 1 to 10 m/day

Extra osseous phase: 75 m/day

Environmental factors affecting the final position of the tooth:Muscular forcesThumb-sucking52Several factors control mesial drift:

(a) Contraction of the transseptal fibers: As the proximal tooth surfaces of adjacent teeth become worn from functional tooth movement, the transseptal fibers of the periodontal ligament become shorter (due to contraction) and thereby maintain tooth contact.

(b) Adaptability of bone tissue: The side of pressure on PDL fibers causes bone resorption, whereas pull on the fibers causes bone apposition (formation). Therefore, as the contact areas of the crowns wear, the teeth tend to move mesially, thereby maintaining contact

Anterior compartment of occlusal force: An anteriorly directed force is generated when teeth are clenched, due to the mesial inclination of most teeth and the forward-directed force generated from inter-cuspal forces. Eliminating opposing teeth results in elimination of biting forces, causing a slowing down of the mesial migration

Pressure from soft tissues: Buccal mucosa and tongue push teeth mesially 53Active eruption: to compensate incisal and occlusal wear

Passive eruption: gradual recession of the gingiva and the underlying alveolar bone

Both active and passive eruption leads to lengthening of clinical crown

Back to main page55Osteoclasts are bone resorbing cells derived form monocyte- macrophage lineage

Giant multinuclear cells with 4-20 nuclei

Osteoclasts resorb hard tissue by separating mineral from the collagen matrix through the action of hydrolytic enzymes

Resorption occurs at the ruffled border which greatly increases the surface area of the Osteoclast in contact with bone

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5 monthsAt birth

1 year2 years3.5 years4.5 yearsShedding of Mandibular incisorFigure Source: Dr. Sandra Meyers57

Deciduous 1st molarFigure from Ten Cates Oral Histology, Ed., Antonio Nanci, 6th edition58

Shed element following shedding of primary incisorComplete resorption of roots

Resorption lacunae seen (arrow)

Most of coronal pulp is intactFigure Source: Dr. Sandra Meyers59

7 years-functional occlusion attainedbut root apex is still not fully formed

15 years incisal wearFigure Source: Dr. Sandra MeyersBack to main page61

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64The six/four rule for primary tooth emergenceFour teeth emerge for each 6 months of age6 months: 4 teeth (lower centrals & upper centrals)12 months: 8 teeth (1. + upper laterals & lower laterals)18 months: 12 teeth (2. + upper 1st molars & lower 1st molars)24 months: 16 teeth (3. + upper canines & lower canines)30 months: 20 teeth (4. + lower 2nd molars & upper 2nd molars)SummaryBy 5 months in utero, all crowns started calcificationBy 1 year old, all crowns completed formationBy 2.5 years, all primary teeth eruptedBy 4 years old, all primary teeth completed root formationSource: http://www.columbia.edu/itc/hs/dental/d9903/lectures/lecture4.pdf65The rules of Fours for permanent tooth development (3rd molars not included)At birth, four 1st molars have initiated calcificationAt 4 years of age, all crowns have initiated calcificationAt 8 years, all crowns are completedAt 12 years, all crowns emergeAt 16 years, all roots are completeSource: http://www.columbia.edu/itc/hs/dental/d9903/lectures/lecture4.pdf66Rules of sixes in dental development6 weeks old in utero: beginning of dental development6 months old: emergence of the first primary tooth6 years old: emergence of first permanent toothSource: http://www.columbia.edu/itc/hs/dental/d9903/lectures/lecture4.pdfBack to main page68Eruption occurs only during a critical period between 8pm and midnight or 1am.During the morning, tooth eruption ceases or even the tooth intrudes a bit. This reflects Circadian Rhythm reflecting the possible involvement and control of growth hormone and thyroid hormone. Hormonal Control MechanismsControl of EruptionA study by Leache et al (1988) of children with growth deficit concluded that children with delayed growth due to growth hormone deficiency or low genetically determined height had delayed tooth eruption. However those with delayed growth for other reasons show normal dental development.This was a large study of children who were shorter than average for their chronological age, although the numbers of children in each group studies were relatively small.

69The time of eruption for primary and permanent teeth varies greatly. A variation of 6 months on either side of the usual eruption date may be considered normal for a given child. Back to main page71Extra oral & Intraoral symptomsFinger chewingLip bitingObject bitingIrritability/restlessnessNight cryingDroolingCircumoral rash and inflammationAppetite lossFlushed cheeksMild temperature elevationEar rubbingGum rubbingInflammation/gingival redness over erupting toothTender swollen gumsTooth erupting72Myths and RealitiesAlthough many studies have suggested associations between teething and a range of signs and symptoms; both local and systemic, the level of evidence remains poor for any cause-effect relationship.

Historically, teething has often been blamed when diagnostic ability has failed . Since the eruption of teeth is a normal physiologic process, the association with fever and systemic disturbances is not justified. A fever or respiratory tract infection during this time should be considered coincidental to the eruption process rather than related to it.

73High temperature (higher than 39C) should not be attributed to teething, and should be investigated

Since eruption takes place over a period of two and a half years, it is not surprising that these coincidental factors emerge. If attention is given to these symptoms, it is often recognized that some other coincidental mild infection is present, usually gastro-intestinal or upper respiratory.

An undiagnosed primary herpetic infection (primary herpetic gingivo-stomatitis) could be responsible for the symptoms of fever, irritability and appetite loss 75If the pain is troublesome, the appropriate dose of paracetamol elixir, preferably sugar-free may be given regularly, every 4-6 hours. Topical medications include gels containing choline salicylate, lidocaine HCl and powders containing benzocaine and paracetamol for temporary reliefUncontrolled application Iatrogenic oral mucosal trauma (chemical burns at the site of application on the mucosa in a 10-month-old boy in Malta)Bonjela, an analgesic drug containing 8.7% choline salicylate in a flavored gel baseCholine salicylate is a synthetic non-steroidal anti-inflammatory based on aspirin,Indicated for mild oral and perioral lesions and 1/4-1/2 inch is applied topically 3-hourly, up to a maximum of six applications per day. The drug has a local analgesic effect although the pressure of application may be the true mechanism of action. Less adverse effects when compared to aspirin, however, according to Sarll and Duxbury, it has been reported to cause salicylate intoxication when applied topically in a child. Not believed to be implicated in Reye's syndrome. If topical therapy is required, it must be applied sparingly to localized areas of dry mucosa. The patient must be regularly reviewed and reassessed76

Paediatric Paracetamol Elixir BPEach 5ml contain 120 mg of paracetamol79HYPOPHOSPHATASIA

CHERUBISM

ACRODYNIA

HYPOPHOSPHATEMIA

CYCLIC NEUTROPENIA

OTHER DISORDERS LIKE: Acatalasia, Chediak-Higashi Syndrome, Coffin Lowry Syndrome, Downs Syndrome, Ehlers-Danlos Syndrome, Hajdu-Cheney Syndrome, Hyperpituitarism, Hyperthyroidism, Juvennille Diabetes, Papillon-Lefevre Syndrome, Progeria,Singleton-Merten Syndrome, and some mlignant diaseases like Histiocytosis, and Leukemias.81Eruption hematoma/Eruption cystA bluish purple, elevated area of tissue, occasionally develops a few weeks before the eruption of a primary or permanent tooth. Blood filled cyst mostly associated with primary second molar or first permanent molar? Trauma during functionSelf-limiting: usually within a few days, the tooth breaks through the tissues and the hematoma subsides Surgical uncovering

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84Eruption Sequestrum Occasionally occurs at the time of eruption of the permanent molars.Starkey et al. (1963) were the first to report the presence of small fragments of calcified tissue overlying the crowns of erupting molar teeth. Generally, these pieces directly overlay the central occlusal fossa, while remaining within the soft tissue and, as the molar tooth erupts through the bone, a small osseous fragment is lost.

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87Ectopic Eruption of First MolarsEctopic eruption is defined as the abnormal eruption of a permanent tooth out of position and causing the resorption of a primary tooth in an abnormal fashion.

A disturbance of the path of eruption in a position different to its normal path

In reference to the first molar, the definition is: an ectopic molar erupts at an angle mesial to the normal path of eruption and atypical resorption of the distal surface of the neighbouring primary second molar.88ClassificationThe disorder was first described by Chapman (1923) and later refined by Young (1957) describing two types of ectopic molar eruption:Jump-Reversible typeHold-Irreversible typeJump: describes a reversible ectopic eruption typified by a mild manifestation allowing the first permanent molar to free itself from under the second primary molar and erupt into normal position. Account for 66% of casesHold: describes a permanent molar erupting with a mesial inclination, causing resorption of the primary molar roots such that the first permanent molar becomes trapped under the second primary molar. The tooth will not erupt until treatment is provided or until the primary molar exfoliates causing further mesial tipping, space loss, migration and rotation of the permanent molar

89AetiologyRemains relatively unknown, however, a number of causes have been suggested:

Genetic factors (familial)Imbalance in the growth of the mandible in relation to the eruption of the first permanent molar, which can encourage continued mesial inclination of the molar and subsequent entrapment under the bulge of the second primary molarArch length deficiencyLarger than normal sizes of all maxillary primary and permanent teethTendency towards a hypo plastic maxillaRetrusive position of the maxilla in relation to the cranial basePronounced mesial inclination of the tooth by 15 degrees on averageDelayed calcification of the affected molarImproper fit of a SSC on a second primary molar placed prior to eruption of 6Cleft lip and palate patients following primary palate repair. 90

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95What are natal and neonatal teeth?Natal teeth- teeth that are already present at the time of birth.

Neonatal teeth- teeth which grow in during the first 30 days after birth.

Precocious Dentition- teeth erupting during the 3-5th month of life

Normal Dentition -8 months

9685% are the deciduous mandibular incisors

97Location85% mandibular incisor maxilla10 times more common in primary teeth

123Possible complications:Delayed exfoliationDelayed eruptionMalocclusionTippingOver eruption of opposing toothLoss of arch lengthDamage to adjacent teeth (alveolar bone and PDL)Denuded root surfaceIncrease difficulty of extractionDecrease alveolar bone support and increased submergenceIn severe cases adaptive tongue thrustRetained root fragments124

125Submerged primary teethHyper or supra eruption126Retained Primary teeth

127Epstein Pearls, Bohn Nodules and Dental Lamina cysts Fromm reported that clinically visible cysts were found in 1028 of 1367 newborn infants. He noted and classified the following three types of inclusion cysts:

Epstein Pearls are formed along the midpalatine raphe. They are considered remnants of the epithelial tissue trapped along the raphe as the fetus grows.

Bohn Nodules are formed along the Buccal and lingual aspects of the dental ridges and on the palate away from the raphe. The nodules are considered as the remnants of mucous gland tissue and are histologically different form Epstein pearls.

Dental Lamina Cysts are found on the crest of the maxillary and mandibular dental ridges. The cysts apparently originated form the remnants of the dental lamina128

Hereditary gingival fibromatosisDown SyndromeCleidocranial dysplasiaHypothyroidismHypopitutarismAchondroplastic dwarfism

Systemic conditions causing delayed eruption of teeth130Downs SyndromeDelayed eruption of both primary and permanent dentitions

35-55% microdontia, clinical crowns are short, conical, small, roots complete

Enamel hypocalcificiation and hypoplasia common

DS patients 50% more likely to have congenitally missing teeth, taurodonts are frequent finding

1/3 more caries resistant than their non-DS siblings

Gingivitis develops earlier and more rapidly and extensively in persons with DS, perhaps because of an abnormality in host defenses. Patients with DS have altered microbiological composition of subgingival plaque, including increased Actinomyces and Hemophilus strains.

131V-shaped palate,

incomplete development of the midface complex,

soft palate insufficiency

Hypotonic O. Oris, Masseter, Zygomatic, Temporalis Muscles

Absent incisors make articulation difficult

High incidence of laryngeal-tracheal stenosis, also upper airway obstruction and sleep apnea common

Scalloped, fissured tongue with bifid uvula, cleft lip/palate, enlarged tonsils/adenoids

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133Cleidocranial DysplasiaRetained primary teethDelayed eruption of permanent teethImpactionAbnormal or absent cellular cementum

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Cleidocranial Dysplasia135

136HypothyroidismCongenital hypothyroidism occurring at birth or during rapid growth period usually causes mental deficiency and dwarfism. The untreated child is usually small and disproportionate person, with abnormally short arms and legs. The dentition is delayed in all stages of eruption.

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The occlusion was normal but with delayed in its development. The maxillary midline supernumerary tooth is coincidental.140

The delayed development in the Juvenile Hypothyroidism patient141HypopituitarismA pronounced deceleration of the growth of the bones and soft tissues of the body will result from a deficiency in secretion of the growth hormone. Delayed eruption of teeth142

Complete primary dentition at the age of 28- years of age143

The roots of the primary teeth have not resorbed to that appreciable degree though some permanent teeth show complete development144Achondroplastic DwarfismAutosomal dominant disorder The maxilla may be small, crowding of the teeth and a tendency for open bite A chronic gingivitis is usually presentDevelopment of dentition is usually delayed

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151 Glenn observed during an examination of 1702 children that 5% had a missing permanent tooth other than 3rd molar. In 97% the formation of 2nd premolar could not be detected radiographically at the age of 5.5yrs and that of the lateral incisor at the age of 3.5 yrs.

Later further studies were done and the causes for the missing tooth/teeth were found : Mutation in the MSX1 gene located at 4p16.1 Mutation in the human PAX9 gene Consanguineous marriage

151153 Secondary characteristics are:Deficiency in salivary flowProtuberant lipsSaddle-nose appearanceDry and scaly skinFissuring at the corners of the mouthPrimary teeth maybe of normal or reduced in sizeThe primary molars without permanent successors have a tendency to be ankylosed.

Development of skeletal structures is normal.

Children presenting with this syndrome have normal mental growth and a normal life expectancy.

Consanguinity increases the likelihood of expression of a trait or condition that is inherited in a recessive manner, and may be one way that a female with a normal karyotype can be affected.

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Back to main page156BibliographyTextbook of Pediatric Dentistry - Nikhil MarwahDentistry for the Child and Adolescent Eighth EditionTen Cates Oral Histology, Ed., Antonio Nanci, 6th editionEssentials of Oral Histology and Embryology. James Avery, 2nd editionColor atlas of clinical oral pathology. Neville, Damm and White. 2nd edition

157Thank You