· Eruption and Shedding
· Non-Bacterial Loss of Tooth Substance
· Discoloration of Teeth
· Transplantation and Reimplantation
· Root Fracture
· Age Changes
Disorders of Eruption and Shedding
Premature eruption , Natal and Neonatal teeth :
Natal and Neonatal teeth:
· Premature : before the proper time
· Usually teeth start to erupt at the age of 6 months + or - , and sometimes as early as 3 months . It might be delayed as well, to the age of 9,12month.some neonate (new born) are born with teeth or start to erupt shortly after birth . these teeth are called :
· Natal - if present at birth
· Neonatal - if erupted shortly after birth
· 80% of these teeth are the mandibular incisors .
Remember: the first teeth to erupt are the mandibular incisors, so common sense .
- Due to this premature eruption there is lack of root formation, and the mobility during eruption might lead to irregularities in its structure (it is still developing) leading to premature loss .
- we might extract them before they are lost if :
- we are scared that the infant might inhale them
- they are causing ulceration to the opposing oral mucosa
- they are causing injury to the mother while nursing
- If we feel that they are stable we can provide them with covering plate
- While nursing rather than extraction.
Local Factors for Other Teeth:
Such as premature eruption of permanent teeth (which is widely seen in our population) as a result of :
Dental caries of deciduous teeth and lack of oral health education, which might lead to malocclusion as well - premature loss of deciduous teeth
Superficial location of tooth germs in the jaws
Endocrine abnormalities:
- lead to generalized premature eruption
- such as increase in GH and hyperthyroidism
Remember:
Increase in GH in children - gigantism
Increase in GH in adults - acromegaly
Retarded Eruption :
General causes:
· Such as :
o Hypothyroidism : leads to cretinism
o Prematurity : born earlier
o Nutritional deficiencies
o Chromosomal abnormalities
Local causes:
· When permanent teeth (as well deciduous but less common) have got the eruptive force but there is sth preventing them .
· it could be :
o Idiopathic
o Migration & traumatic displacement of tooth germs
· As if a child was exposed to a trauma that moved his tooth germs far in the jaw or to become impacted by other teeth
· Abnormally large crowns : can’t find space for eruption
Delayed Eruption and Multiple Supernumerary Teeth:
- Any condition which have multiple or even single supernumerary teeth might obstruct the track of chronology ,
- Or the supernumerary teeth itself can’t erupt .
- Such in Cleidocranial Dysplasia : a condition associated with :
- Total or partial absence of the clavicles
- Cranial sutures abnormalities
- Hemifacial hypoplasia
- Depressed nasal bridge
- Multiple impacted supernumerary teeth
Premature Loss :
· causes :
1-dental cries and its sequelae* - such as pulpitis
2- Chronic periodontitis *
3- Aggressive periodontitis
· Periodontitis is an inflammation that start with gingivitis and progress to the periodontal fibers and the alveolar bone .
· There is a variant of periodontitis that isn’t related to poor oral hygiene - aggressive periodontitis
4- Hypophosphatasia
5- Papillion-lefèvre syndrome - also known as palmer planter Hyperkeratosis
* The most common causes dental caries + periodontitis
Persistence of Deciduous Teeth :
- it is also termed as : retained or submerged deciduous teeth
- the condition in which deciduous teeth don’t shed at the time they should
- A case for eg. is : when the development of the successor teeth is retarded, so it won’t erupt and the deciduous will persist in the mouth
- Another eg. is: when there is a congenitally missing permanent teeth the deciduous may remain in its position .
- so persistence of deciduous teeth result from failure of eruption of permanent successor because it is missing , displaced or lack formation
A generalized condition is found in cleidocranial dysplasia .
e) Impaction of Teeth:
- A very common eg. is 3rd molar impaction due to lack of space
- Other teeth might be affected such as : maxillary canine , mandibular 2n premolar .
- Impacted teeth : teeth which remain unerupted or partially erupted beyond the expected time
- It might affect 1 or more teeth
- It might be symmetrical : on the Rt + Lf or in the upper + lower
- Is rare in deciduous
- When a tooth is partially erupted it might cause problems :
The gingiva is opened to the oral cavity - accumulation of food and debris
- hard to clean - caries , periodontitis or any source of infection
- it might cause resorption in the adjacent tooth
Local causes:
1-Abnormal position of germ Æ too far in the jaw
2-Lack of space Æ such for 3rd molar and maxillary canine
3-Supernumerary teeth Æ such in cleidocranial dysplasia
4-Cysts (odontogenic tissues are capable of forming them)
5-Tumors(odontogenic tissues are capable of forming them)
6-Cleidocranial dysplasia
Complications:
e Resorption of impacted or adjacent teeth
e Formation of dentigerous cyst
· Dentigerous cyst :is a developmental cyst around the crown of impacted teeth that result from the accumulation of fluids between the enamel and residual enamel epithelium
e Formation of odontogenic tumors
f Another term is embedded teeth : teeth which remains unerupted due to
Lack of eruptive force in the absence of a physical barrier
Remember: impacted - physical barrier
But usually people use impacted for every thing.
f) Reimpaction of Teeth :
f Occur when the alveolar process doesn’t grow enough and the tooth become ankylosis with adjacent bone.
Ankylosis : the union of 2 bony structures .Cementum is similar to the bone structure.
Remember: the alveolar processes of the deciduous teeth grow to accommodate the size and length of the permanent teeth and to reach the correct occlusion.
- As a result there is absent of PDL fibers in that aria
- Also known as infraocclusion or submerged teeth
- Called reimpaction because it is infraocclusal (impacted from the normal occlusion)
- In some situation neighboring teeth tilt over affected tooth, and it may be completely covered by mucosa
- Mostly affects the deciduous mandibular 2ed molar lacking a successor 2ed premolar
Non Carious Tooth Substance loss
Attrition :
· wearing away of tooth substance during tooth to tooth contact- during grinding of teeth against each other
· it is a slow physiological process that appears more in elderly
· might be accelerated by abrasive foods
· pattern:
§ incisal edges of incisors,
§ occlusal surfaces of molars,
§ palatal cusps of maxillary teeth,
§ buccal cusps of mandibular teeth
You might be surprised of the presence of Approximal attrition on the proximal surface results from the movement of PDL fibers during eating ,talking,…etc so the contact points become flat as a result teeth tend to slightly move toward the mid line – mesial migration
f More pronounced in males
f Abrasive food property affects the rate
f Pathological attrition may result from
1- Abnormal occlusal relationship
2- Bruxism and habits such as tobacco and betel chewing
3- Abrasive dust particles - consist of silica
4- Abnormal tooth structure such as amelogenesis imperfecta and
dentinogenesis imperfecta - weakness of the structure
f Exposed dentin becomes discolored yellow to brown and it becomes attritic faster than enamel, cause it is softer, creating cup-shaped defects or wear facet
f Formation of reactionary dentine protects pulp
f And there is formation of dead tracks and translucent zones.
Abrasion :
- pathological wearing away of tooth structure due to repetitive friction of a foreign body
f Examples:
1- Nuts and million seed abrasion
2- Toothbrush abrasion
- due to roughness and poor technique
- brushing motion should be vertical + circular with a smooth brush
3- Habitual abrasion in pipe-smokers
4- Occupational abrasion e.g. hair-grips, nails, musical instruments
5- Ritual abrasion - related to certain tradition
Abfraction :
Loss of tooth structure that results from repeated tooth flexure caused by occlusal stresses
Flexure: blending
f enamel tend to blend to some extant at stress then it will fracture
f while dentin is able to withstand greater tensile stress than enamel
f When eccentric occlusal forces are applied to a tooth, tensile stress is concentrated at cervical fulcrum, leading to flexure that may produce enamel cracks
f Cracked enamel can be lost or more easily removed by erosion or abrasion
Erosion :
f loss of tooth structure resulting from chemical action (acid action)
Dietary erosion :
f Excessive intake of acidic beverages or sucking of citrus fruits- palatal surfaces of teeth and labial surfaces of maxillary incisors
Occupational erosion:
f e.g. battery factories- labial surfaces of maxillary and mandibular incisors
Acid reflux or chronic vomiting:
f e.g. anorexia, bulimia nervosa, chronic alcoholism as well in hernia
Idiopathic:
Resorption :
f Usually the root resorp but sometimes the crown resorp as well such in impacted teeth
Physiological resorption:
f Is seen in the root of deciduous teeth prior to shedding
f Sometimes it occurs as a result of permenant teeth movement and called transient resorption
f Transient microscopic areas of superficial resorption of roots of permanent teeth, repaired by cementum or bone-like tissue apposition
Pathological resorption :
- External - start from the root surface
- Internal - start from the pulp
The cells of action are osteoclast or might call them odontoclast
1- External resorption :
f Might be associated with: Periapical inflammation
e Results from the progression of dental caries , pulpitis , pulpal necrotic tissues through apical foramina
e Inflammation might cause - bone resorptionroot resorption excessive mechanical force e.g. improper orthodontic treatment
e Orthodontics is based on the movement of teeth resulted from the resorption and deposition of bone
neoplasms or cysts transplanted or replanted teeth
e Transplantation: the placement of a tooth in an another socket
e Reimplantation : the placement of the lost tooth in its own socket idiopathic, burrowing type in cervical area - no known cause
Crowns of impacted teeth
2- Internal resorption :
f Occurs from the pulp chamber to the outside
f The clasts originate from it and we call them dentinoclasts
f So a vital pulp is needed
f May be:
Secondary to pulpitis
Idiopathic
f Clinically we start to see the pulp through enamel - pink tooth or by a radiograph
Remember: pink because it is vascularised
Discoloration of Teeth
By:
a) Surface deposits - extrinsic staining such as smoking , coffee , tea
b) Changes in the structure or thickness of the dental hard tissues
c) Diffusion of pigments into the dental hard tissues after their formation
d) Incorporation of pigments into the dental hard tissues during their formation
What is the difference between pigments and stains ?
- Pigments : produced by the body
- Stains : are extrinsic
Extrinsic Staining :
f Causes:
1- Foods and drinks - usually transient
2- Chromogenic bacteria- pigment producing bacteria
e Teeth apperes dark brown to black and they are usually caries resistance
e But these stains are usually hard to remove
Topical medications and mouth rinses
Tobacco products
b) Changes in Structure or Thickness of Dental Tissues :
f Any abnormality in dental tissues
f Causes:
1-Dental caries
2-Enamel hypoplasia: e.g. fluorosis (environmental), amelogenesis
imperfecta (hereditary) , enamel opacities
3-Dentinogenesis imperfecta
4-Dentinal dysplasia type II
5-Age changes
c) Diffusion of Pigments into Dental Tissues After Formation :
f At this stage the tooth isn’t vital and you can till from its appearance
f Examples:
1- take up of food & tobacco stains by exposed dentin
2- restorative & endodontic materials : amalgam sometimes stains
3- Pulp necrosis
Incorporation of Pigments into Dental Tissues During Formation :
f Examples:
1- Congenital hyperbilirubinemia - neonatal jaundice - green to yellowish brown
2- Congenital porphyria - pinkish-brown - red fluorescence under UV light
3- Tetracycline intake during pregnancy or childhood - yellowish changing into brown
eThe most important
eInfant deciduous and maybe first molars become stained
eSo it is contraindicated to prescribe this antibiotic in pregnancy and childhood conditions
Transplantation and Re-implantation
f Reimplantation :
eReturning a tooth to its socket after avulsion.
eSupposing a child while running has lost his incisor if we try to re-implant it within an hour , and we’ve already preserved it in milk
(Body temperature), then the process might success .
f Transplantation:
eTransfer of a tooth to another location in the jaw
eIt is rarely done
eSupposing that some one has lost his 1st molar it could be replaced by for e.g. his 3rd molar
f Both are associated with resorption
f Other complications:
Loss of pulp vitality, failure of root completion, poor periodontal healing
Root Fracture
f As a result of trauma
f Occur at different levels of the root
f The outcome depends on :
1-presence or absence of infection - if the gingiva is opened or the tooth is carious there might be failure
2-vitality of pulp
Position of fragments - it is better when it is more toward the apex
3-degree of comminution
4-Location of fracture
5-Mobility of coronal fragment
f Pattern of healing:
1- Fragments become united totally or partly by calcified repair tissue - such as cements
2- Fractured surfaces become rounded off and clothed by cementum with formation of fibrous tissue in between
3- Fractured surfaces become rounded off and clothed by cementum with formation of fibrous tissue and bone in between
Age Changes
a) Enamel become:
1- More brittle -more cracks
2- Less permeable
3- Darker
b) Dentine:
1-Continued formation of secondary dentin with reduction or obliteration of pulp chamber
2-Continued formation of peritubular dentin results in transluce dentin
e The increase in thickness around the tubule results in this translucency
3-Roots become brittle
e So becoming thicker doesn’t mean becoming stronger
c) Cementum :
1-Continued formation and increased root thickness
2-Hypercementosis in presence of other causes
In general if you look at an old tooth you’ll see:
- Narrowed pulp chambers and maybe some calcified portions
- Tertiary dentine
- Enamel cracks
- Gingival ressetion
