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Copy of Dental Anatomy Seminar
Transcript of Copy of Dental Anatomy Seminar
Diseases Related to Shape of teeth
Diseases Related to Size of teeth
Diseases Related to Number of teeth
Tooth size is variable between different races and sexes. The presence of unusually small teeth is termed microdontia. The presence of teeth larger than average is termed macrodontia. Although heredity is the major factor, both genetic and environmental influences affect the size of developing teeth. The deciduous dentition appears to be affected more by maternal intrauterine influences. The permanent teeth seem to be more affected by environment.
The term microdontia is applied when the teeth are smaller than usual.
It is strongly associated with hypodontia. Females demonstrate a higher frequency of microdontia and hypodontia.
Microdontia is divided into three types:
-Relative generalised microdontia
-True generalised or Diffuse microdontia
-Isolated or regional microdontia
Relative Generalised Microdontia : Normal or slightly smaller sized teeth may appear small when widely spaced within jaws that are larger than normal. Thus, giving an impression of microdontia. Inheritance of jaw from one parent and teeth from another parent may lead to this condition.
Dentition in which the teeth are smaller than normal and widely spaced within the arch.
Diffuse Microdontia: All teeth are well formed but smaller than normal size. It is uncommon but may occur as an isolated finding in Down's syndrome, in pituitary dwarfism and in association with a small number of rare hereditary disorders that exhibit multiple abnormalities of the dentition.
Isolated Microdontia: Also called as localised microdontia. The maxillary lateral incisor is affected most frequently and typically appears as a peg shaped crown overlying a root that often is of normal length. The mesiodistal diameter is reduced, and the proximal surfaces converge toward the incisal edge. In addition, isolated microdontia often affects the third molars. When a peg shaped tooth is present, the remaining permanent teeth often exhibit a slightly smaller mesiodistal size.
A healthy, attractive smile is often characterized by even rows of nicely sized teeth. But sometimes, as teeth are developing and filling in the mouth and gum line, abnormalities occur and one or several teeth grow at a different rate than others. The condition, known as macrodontia, is when a tooth (or teeth) grows bigger than normal, and this difference in size is noticeable in comparison to surrounding teeth. While macrodontia isn't very common, most of us have probably seen someone whose smile is dominated by large central incisors.
Macrodontia is associated with hyperdontia. Usually, males have a greater prevalence of macrodontia.
The main types of macrodontia include the following:
~Localized or regional macrodontia -- One tooth or teeth in
one location or on one side of the mouth is larger than others, but
otherwise normal in every other way.
~True generalized or diffuse macrodontia -- A very rare form where all teeth in the mouth are larger than what would be considered normal for a person's mouth. It has been noticed in association with pituitary gigantism, otodental syndrome, XYY males and pineal hyperplasia with hyperinsulinism.
~Relative generalized macrodontia -- Teeth may be normal size or slightly larger than normal but appear very large due to the small size of a person's jaw. This is not true macrodontia, but is relative to jaw size and gives the appearance of macrodontia.
~Physical appearance is one of the most obvious complications of macrodontia and microdontia but something less apparent is what happens inside the face and jaw of people who have uneven teeth. When one or more teeth are outsized or undersized a person's bite may be uneven, leading to jaw and joint disorders, as well as pain in the face and skull area. These maxillofacial concerns can cause mild, acute pain or long-term, extreme pain and should be treated. Chewing also can be less effective depending on the location of the macrodont or microdont, which can lead to digestive problems if food is not properly or completely broken down before swallowing. Always consult with a dental professional or pediatrician if macrodontia is developing as a child grows or is suspected.
~Differences in size and rough surfaces also can lead to problems with effective cleaning and cavities. Gum care in these instances is especially important in order to prevent pockets where teeth and gums aren't matching up with adjacent teeth.
Complications and care
Treatment of microdontic dentition is not necessary unless required for aesthetic considerations. Maxillary peg laterals often are restored to full size by porcelain crowns.
Not all cases of macrodontia require treatment, though many are repaired in order to avoid problems with the bite, dental cavities from irregular surfaces and the overall appearance of a person's smile.
Scaling back the tooth size or extracting the tooth are options for treating or correcting macrodontia. Replacing the natural tooth with a prosthesis or artificial tooth or teeth in the case of multiple macrodonts allows for very even matching with the normal-sized natural teeth.
Treatment and Prognosis
-Schizodontism- Single tooth bud-splits into two.
Synodontism- supernumerary tooth + tooth germ
-Tooth count is normal when the anomalous tooth is counted as one.
-Single root and canal, but two pulp chambers.
Gemination cont ….
Radio graphical Images:
Single root canal but two pulp chambers
Affects mainly permanent max. incisors and deciduous mand. incisors.
Dental arch asymmetry
Gemination cont. :
Primary – no need.
Permanent- If too wide- selected shaping + placement of full/partial crown.
Surgical division + root canal
Gemination cont. :
Union of two normally separated tooth germs.
Single enlarged tooth or joined (i.e)double tooth, in which tooth count reveals a missing tooth.
Can happen with supernumerary tooth.
Depending upon the stage of development at the time of the union:
before the calcification of the tooth has
occurred. Enamel, dentin, pulp and cementum.
later stages of development; limited to roots
Fusion cont. :
Crowding, abnormal spacing, ectopic or delayed eruption of the permanent tooth.
Show more pronounced labial or lingual groove – so more susceptible to caries.
Placement of a fissure sealant.
Fusion cont. :
Patients who exhibit pulpal or coronal anatomic features are resistant to reshaping and require surgical removal with prosthetic replacement.
replacement of a missing bodily part with an
Fusion cont. :
-Two fully formed teeth, joined along the root surfaces by the cementum after root formation.
-Usually seen in maxillary and posterior regions.
often involves a second molar tooth in which its roots closely approximate the adjacent impacted third molar.
Often involves carious molars in which the apices overlie the roots of horizontally or distally angulated third molars.
Concrescence cont. :
deposition of cementum
Surgical separation - may be necessary if it obstructs eruption of permanent teeth.
Or extraction: careful, can cause trauma to the jaw or result in removal of may teeth.
Concrescence cont. :
Dens invaginatus and dens evaginatus
Tooth development occurs through the interaction between oral tissues during embryogenesis. Alteration through odontogenesis(teeth development) may cause tooth morphological alterations, two of these could be Dens invaginatus or Dens evaginatus.
Dens invaginatus is a developmental disturbance that can occur on primary, permanent, or supernumerary teeth resulting from invagination of the enamel organ toward the dental papilla(gives rise to dentin and pulp) before mineralization, this means during morpho-differentiation stage of tooth development.
The invagination, starting from the the tip of the cusp, may be limited to the tooth crown or invade the root and sometimes even reach the root apex.
Clinically, unusual crown morphology (peg shaped) or a deep foramen coecum may be important to indicate the probability of a dens invaginatus and it is necessary to acquire radiographs.
If one tooth is affected in a patient, the contra lateral tooth should be investigated, although it is common to find invaginations bilaterally.
Dens invaginatus cont..
Extends through the root & perforates in the apical or lateral radicular area.
confined to the crown.
Extends below the CEJ .
The incidence ranges from 0.04% to 10% and primarily affects the permanent dentition, especially the maxillary lateral incisors, although primary teeth may also be affected and bilateral occurrence is not uncommon.
Dens invaginatus is not longer an uncommon clinical finding in permanent teeth and probably occurs more often than other developmental anomalies, but may be easily overlooked because of absence of any significant clinical signs of the anomaly.
This is unfortunate as the presence of an invagination is considered to increase the risk of caries, pulpal pathosis and periodontal inflammation.
Pulp necrosis often occurs rather early, within a few years of eruption, sometimes even before root end closure.
A preventive or conservative treatment is indicated for teeth that belong to type I and II to maintain the pulp vitality .
DI type II: vital, cleaning of the invagination space and obturation with flowable composite.
(Follow ups are recommended)
A surgical treatment can be performed in cases of endodontic failure and in teeth which cannot be treated non-surgically because of anatomical problems.
An extraction of DI is indicated only in supernumerary teeth or when endodontic therapy and apical surgery have failed or are not possible
Dens evaginatus – cusp-like elevation of enamel located in central groove of permanent premolar or molar teeth.
The defect,which is often bilateral is an anomalous tubercle or cusp, located in the center of the occlusal surface.
Dens evaginatus (accessory cups)
The talon cusp, or dens evaginatus of anterior teeth, is an uncommon dental developmental anomaly, characterized by the presence of an accessory cusp like structure projecting from the cingulum area or cementoenamel junction.
Accessory cusp located on palatal surface of mesiolingual cusp of maxillary first molar.
Patients with cusp of carabelli require no therapy unless a deep groove is present between the accessory cusp and the surface of the mesiolingual cusp.the groove should be sealed to prevent carious involvement.
CUSP OF CARABELLI
Talon cusps occur more frequently in the permanent dentition (75%) than the primary dentition (25%).
The maxillary lateral incisors are most frequently involved (67%), followed by the maxillary central incisors (24%) and canines (9%).
About 9% of the patients with true talon cusps on one or more permanent maxillary incisors may develop supernumerary teeth in the same region. Because DE may occur due to hyperactivity of the dental lamina and therefore, a supernumerary tooth can be expected.
Tubercles have an enamel layer covering a dentin core that usually contains pulp tissue.
A talon cusp is susceptible to pulp exposure from wear or fracture because of malocclusion,
Pulp exposure can lead to pulp death and periapical abscess, often before completion of root formation.
An essential step, especially in case of occlusal interference, is to reduce the bulk of the cusp gradually and periodically and application of topical fluoride.
Presence of enamel in unusual locations.
-Consist entirely of enamel or contain underlying
dentin and vital pulp tissue.
-Hemispheric structures projecting from surface
of root, localized bulging of Odontoblastic layer.
-Results in induction of enamel
-Most frequently found on the roots of maxillary
molars, followed by mandibular molars.
-Majority occur on the roots and cemetoenamel
-As many as 4 pearls can be found on one tooth.
-Pearls are well-defined, radiopaque
-Enamel surface precludes normal
periodontal attachment with connective
-Hemidesmosomal junction may exist, less resistant to
-Rapid loss of attachment is likely if separation occurs.
-Exophytic nature of pearl is conducive to plaque
retention and inadequate cleansing.
TREATMENT AND PROGNOSIS
-Area of pearl detection should be viewed as weak
point of periodontal attachment.
-Meticulous oral hygiene should be maintained to
prevent localized loss of periodontal support.
-Occur along the surface of dental roots.
-Extensions represent dipping of enamel from cementoenamel junction towards bifurcation of molar teeth.
-Mandibular molars are slightly more affected than maxillary molars.
CERVICAL ENAMEL EXTENSIONS
-Greater the degree of cervical extension, higher the
frequency of furcation involvement.
-Also been associated with the development of
-Develop along the buccal surface over the bifurcation,
called Buccal Birfurcation Cysts.
TREATMENT AND PROGNOSIS
-Flattening or removing enamel in combination with an
excisional new attachment procedure.
-Development of an increased number of roots on a tooth.
-Permanent molars(especially 3rd molars), mandibular cuspids and
-Root is either divergent and easily seen on radiographs, or small,
superimposed over other roots and difficult to ascertain.
TREATMENT AND PROGNOSIS
-No particular treatment required, but detection of accessory
root is important for other therapies.
The term “Taurodontism” comes from the Latin-Greek word meaning (‘bull tooth’)
Taurodontism is an enlargement of body and pulp chamber of multirooted tooth with apical displacement of pulpal floor and bifurcation of the roots.
Clinical and Radiographical features:
The unusual nature of this condition is best visualized on the radiograph. Affected teeth tend to be rectangular and exhibit pulp chambers with dramatically increased apico-occlusal height and a bifurcation close to the apex.
-They classified according to their severity into hypo-, meso- and hypertaurodont forms.
-Hypotaurodontism being the least pronounced form.
-Mesotaurodontism the moderate form.
-Hypertaurodontism being the most severe form in which the bifurcation or trifurcation
occurs near the root apices.
Mandibular second molar.
Taurodontism may be unilateral or bilateral and affects permanent teeth more often than deciduous teeth. The teeth involved are almost invariably molars. when this occurs the first molar is least affected with increased severity in second and third molar respectively . Only sometimes only a single tooth and at other times several molars in the same quadrant are affected.
Taurodontism may occur as an isolated trait or as a component of a specific syndrome like down’s, klinefelters , ectodermal dysplasia and amelogenesis imperfecta .An increased frequency of Taurodontism has been reported in patients with hypodontia ,cleft lip and cleft palate
Treatment and prognosis:
Patients with taurodontism may require no specific therapy. Coronal extensions of the pulp is not seen therefore the process does not interfere with routine restorative procedures but the enlarge pulp is of significance when endodontic treatment is required.
Hypercementosis is non-neoplastic deposition of excessive cementum continuous with the normal radicular cementum.
Clinical and Radiographical features
Radiographically, affected teeth demonstrate a thickening or blunting of the root . The enlarged root is surrounded by a radiolucent PDL (periodontal) space and the adjacent intact lamina dura.
Hypercementosis can only be visualized with a panoramic radiograph. In the area highlighted you will notice a large whitish mass around the roots of a tooth. This mass is an increased number of cells that line the root surface of the tooth.
Hypercementosis may be isolated ,involve multiple teeth or appear as a generalized process. In a study it was shown that mandibular molars were most frequently affected , followed by mandibular and maxillary second premolar and mandibular fist premolars. Hypercementosis occurs predominantly in adulthood and the frequency increases with age .
Several local and systematic factors are associated with an increased frequency of cemental deposition. Significant hypercementosis occurs in patients with pagets disease.
Hypercementosis –excessive production of cellular cementum
The periphery of the root exhibits deposition of an excessive amount of cementum over the original layer of primary cementum.
Treatment and diagnosis
Patients with hypercementosis require no treatment. Because of thickened root occasional problems have been reported during the extraction of the tooth. Sectioning of the tooth in certain cases may be necessary in certain cases
-Anodontia- total lack of tooth development.
-Hypodontia- lack of development of one or
-Oligodontia (subdivision of hypodontia)-
lack of development of six or more teeth.
-Hyperdontia- development of increased
number of teeth.
DEVELOPMENTAL ALTERATION IN THE NUMBER OF TEETH
-Failure of teeth to form is one of the most common
dental developmental abnormalities.
-Hypodontia is uncommon for deciduous dentition.
-Absence of a deciduous tooth is associated strongly
with increased prevalence of a missing successor.
-Missing teeth in the permanent dentition are not rare, with third molars being the most commonly affected. After the molars, the second premolars and lateral incisors are absent more frequently.
-The most critical discovery related to hypodontia revolves around the mutation of the gene AXIN2.
-It is a rare genetic disorder characterized by the
congenital absence of all primary or permanent
teeth. It is associated with the group of skin and
nerve syndromes called ectodermal dysplasias.
-There can be partial anodontia or hypodontia.
-Treatment is using dental implants or dentures.
-It is the development of increased number of
-The most common site is the maxillary incisor
region followed by the maxillary and
mandibular third molars, premolars, canines
and lateral incisors. Supernumerary mandibular
incisors are very rare.
Occasionally normal teeth may erupt into an inappropriate position. This pattern of abnormal eruption is called dental transposition.
* Oral and Maxillofacial Pathology
Authors: Neville,Dam, Allen, Bouquot
* Essentials of Oral Patholgy
* Oral Pathology -Clinical Pathology
Author: Regezi Scuibba Jordan