Dental Anomalies

Dental Anomalies

• Introduction

Anomaly constitutes an irregularity, a deviation from what is usual or considered as such.

        From this point of view, the dental system is defined by standards that concern the number of teeth, their shape, their location on the arch, the histological constitution of each one, and it is not until eruption, a physiological phenomenon of which time is an intrinsic factor, that it does not usually take place within a precise chronological framework with specific limits.

2.  Definition

These are alterations of the coronal or radicular structures and variations in the number, location and eruption of one or more teeth.

These anomalies result from a disorder occurring during the formation of the teeth, of exogenous or endogenous origin.

3. Etiology of Dental Anomalies

They are based on two types of etiological factors:

1. Genetic etiology:

Several mechanisms can come into play:

Monogenic mechanisms:

In this case, only one gene at the chromosome level is affected, the alterations are limited to the teeth and are caused by highly specialized genes (called “dental genes”).

Pleiotropic mechanisms:

The mutation of a “pleiotropic gene” is the mechanism responsible for dental anomalies found in various genetic syndromes, where the anomaly affecting the teeth is one among others that are located at different levels of the organism. 

3.2 Non-genetic etiology :

These are environmental factors within the jaws that cause:

• Number and position anomalies in cleft lip and palate or first arch syndromes.

Abnormalities of shape and structure due to mechanical trauma or radiotherapy, metabolic or nutritional disorders (rickets, fluorosis, renal failure), or to pharmacological agents such as tetracyclines.

4. Classifications: 

We will retain the following classification:

1. Eruption anomalies
2. Shape anomalies
3. Number anomalies
4. Siege Anomalies (Dystopias)
5. Structural abnormalities (dysplasia)
6. Volume anomalies
7. Eruption anomalies:

 Tooth eruption is a stable physiological phenomenon, occurring at relatively fixed dates. Any disturbance results in either premature or delayed eruption.

1. Premature eruptions:

Natal and neonatal teeth: Natal teeth, present at birth, do not constitute a case of early eruption, since they are supernumerary mucosal odontoid formations, very little or even not calcified, quickly eliminated, and which generally sit at the location of the future upper milk incisors, but more often lower. 

Early teeth: Appearance on the arch of well-formed teeth before the normal date of their eruption. (Temperature teeth before 5 months, and permanent teeth before 5 years of age.)

• Etiopathogenesis:
  • General causes:
    • Hyperthyroidism (precocious puberty)
  • Local causes:
    • Superficial position of the germ.
    • In the case of permanent teeth due to premature loss of the temporary tooth.

Can be found in the context of syndromes:

Synd. Sturge-Weber

Synd. Sotos 

Synd. Turner (XO)

2. Delayed Eruptions

We only speak of delayed eruption or delayed eruption after 12 months from the normal date of development for permanent teeth (delayed eruption after 7 and even 8 years) and after 7 months for temporary teeth.

Before confirming such a delay it is necessary to ensure that the teeth are present and in the correct position.

Etiology:

When the delay in eruption is localized to a tooth, it is a local etiology .

• Gingival obstructions: congenital hyperplasia of the gingiva.
• Tumor obstacles: pericoronary cyst. 
• Dental obstacles: DDM due to relative macrodontia, supernumerary teeth and odontomas. 
• Bone obstacle: osteopathies, etc.
• Germ anomaly: traumatized, bent root

When the delay is generalized to the entire set of teeth, it is a general etiology :

• Vitamin deficiencies: rickets, scurvy.
• Genetics: as in Down Syndrome, Singleton-Merten Syndrome…

2. Shape anomalies

These abnormalities are generalized or localized, affecting either the dental crown, the dental root, or the entire tooth.

Dental Anomalies

Partial coronary dysmorphias 

The supernumerary cusps 

It is a defect transmitted by a so-called structural gene which controls the morphodifferentiation of the tooth bud.

Incisors:

Abnormal development of the cingulate, the major form of incisive cingulate hypertrophy is the talon cusp Shovel-shaped incisor: the two lateral edges have a disproportionate relief on the palatal side.

Canines:

The usual anomaly is the abnormal development of the cingulate, sometimes so developed that it gives the canine the appearance of a premolar (premolarization). An accessory tubercle may also exist on the vestibular surface. 

Premolars:

The existence of an accessory marginal ridge can modify the morphology of the vestibular tubercle and give the crown a tricuspid appearance.

In other cases, there is a true accessory tubercle on the vestibular surface giving the tooth the appearance of a molar (molarization).

Molars: 

At the level of the first upper molar, three cusps or three vestibular cusps and one palatal cusp can be found.

Carabelli tuber:

Carabelli and von Lunkas showed in 1844 the possible existence of an accessory mesiopalatine tubercle which is considered as a supernumerary cusp at the level of the first upper molar.  

 BOLK tuber:

It is a common mesio-vestibular accessory paramolar tubercle on the 2nd and 3rd upper molars.

Total coronal-radicular dysmorphia: piano key teeth.

Root dysmorphias:

They are either anomalies of direction and number or of shape and size.

Number anomalies:

Additional roots are frequently found on the lower permanent canines, or two roots for the upper first premolar, one vestibular and the other palatal, as one might find a wisdom tooth with seven roots.

Shape anomalies:

Curvatures which are the consequence of an obstacle during root growth (cyst, impacted tooth, etc.) the root will be bent or hooked if growth continues in a different direction.

Taurodontism:

Dysmorphism discovered on radiological examination, characterized by a large pulp chamber of the premolars but especially of the molars and no tightness at the level of the enamel-cementum junction.

Apical displacement of the furcation results in an increase in cameral size.

Dental Anomalies

Pearls, nodules, enamel projection:

These are developmental anomalies formed from an evagination of the internal epithelial layer.

Enamel pearls can be intra or extra dental with coronal, cervicoradicular localization. Most often found at the bifurcation of the roots of the upper molars.

Concrescence:

It is the union of 02 teeth by their roots through the cementum, it mainly concerns the upper incisors. It occurs during the formation of the roots.

Coalescence:

It is the union of two teeth by a very dense bone tissue. The two teeth retain all their individuality.

Fusion: synodonty

It is a developmental anomaly consisting of the union, most often by the dentine, of two normal germs at the time of their formation.

Gemination: 

Partial: It is an incomplete division of a tooth germ.

 Clinically, it is a simple notch of the incisal edge of an incisor. It is common in temporary dentition at the level of the incisor-canine region. Total  (schizodontia): it is rare, there is formation of a supernumerary twin tooth.

3. Number anomalies

Dental Anomalies

Number anomalies appear either as an increase or reduction in dental material.

They may be accompanied by other anomalies of shape and/or volume, with retention of the corresponding temporary tooth.

• Hypodontia: is a number anomaly defined by the absence of a dental unit, in relation to the absence of the corresponding germ ( agenesis )

This is most often an “end of series tooth”:

• 3rd ^molars (10 to 35% of cases)
• Upper lateral incisors
• 2nd ^premolars .

• Anodontia: This is the total absence of all temporary and permanent teeth due to complete agenesis. (extremely rare)
• Oligodontia: This is the absence of a large number of teeth, observed in syndromes such as Christ-Siemens syndrome.

Hyperdontia: This is an increase in the number of teeth due to localized hyperactivity of the dental lamina 

We usually distinguish: 

Extra tooth: If the tooth has a harmonious shape, it only touches one tooth at a time (lateral incisor, molar or premolar).

Supernumerary tooth: (Mesiodens or odontoid) if the tooth has an atypical or dysmorphic shape, in excess of the arch or included, most often of reduced volume, located behind or between the upper incisors.

In the posterior sectors we sometimes find a 3rd premolar, a 4th or even a 5th molar having the appearance of wisdom teeth.

4. Siege Anomalies: Dystopias

Heterotopia:

It is the appearance of a tooth outside the dental arch.

Example : 

DDS in the ascending branch, evolution of a canine in the orbital cavity…

Ectopy:

A tooth is said to be ectopic if it is located near the alveolar base but outside the crest.

The transposition:

It is a positional anomaly in which two teeth, most often adjacent, swap their respective positions on the arch.

It can be partial or total. The most common case is that of the canine and the first or second upper premolar.

Transmigration  :

It is the movement of a tooth which during its eruption gains an unusual place on the arch. The most frequent case is that of the lower canine which gains an unusual place, sometimes contralateral for example between the contralateral canine and lateral incisor, 

The rotation:

The tooth occupies a normal position on the arch but has rotated 45 to 180° around its longitudinal axis.

It affects the second upper premolar which can undergo a rotation of 180°.

Anastrophy:

This is a rare anomaly characterized by the reversal of a germ otherwise in its place, the pivoting of 180° around a mesio-distal axis places the root in a buccal direction. The eruption is generally prevented and the tooth remains included.

This anomaly usually concerns the supernumerary teeth, in particular the mesiodens which can eventually erupt into the nasal cavity or into the maxillary sinus.

Ankylosis:

It is the more or less complete reduction of the physiological mobility of a tooth. Frequently observed on temporary molars, rarely on permanent teeth.

Clinically, the tooth is noted to be immobile. Its percussion gives a clear sound.

Radiologically, we note a thinning of the ligament image or even its disappearance.

Inclusion:

All teeth go through a stage of physiological inclusion. Pathology is considered present when the tooth remains trapped in the bone and soft tissues beyond the normal eruption date.

5.  Structural anomalies:

These are defects in the structure of the hard tissues of the teeth that occur during odontogenesis. These defects affect one tooth or several teeth or all teeth, both in the temporary and permanent dentition. Structural defects affect either the enamel, the dentin, the cementum, or all the hard tissues of the tooth.

Dental Anomalies

Enamel abnormalities:

The structural anomalies and the maturation anomalies of the enamel, both hereditary and acquired, will be successively considered.

1. Hereditary amelogenesis imperfecta

It is a hereditary and congenital condition and affects both temporary and permanent teeth. The changes are limited to the teeth, which involves highly specialized genes.

The shape and volume of the teeth are affected by deterioration of the enamel and by premature attrition: the incisors lose their sharpness, the canines their points and the molars their cusps. 

Type I hypoplasia

The hypoplastic form (60% of cases) results from a matrix deficit.

These are quantitative anomalies most often affecting both dentitions, during which there is a decrease in the amount of enamel matrix deposited during amelogenesis. The enamel, when it exists, is immature and of reduced volume. 

Type II hypomaturation

The hypomature form is common (40 % of cases).

In these cases, the enamel is of normal thickness but its hardness is less. The appearance shows yellow-brown marbling in places, or whitish opacities, localized at the free edge of the tooth. Radiologically, the enamel density appears a little weakened and the contrast with the dentin less marked. 

Type III hypomineralization

The hypomineralized form (7 %)

These are qualitative anomalies, due to a defect in the mineralization of the enamel, which affect both sets of teeth.

2. syndromic amelogenesis imperfecta

These are most often hypoplasias, sometimes accompanied by hypomineralization.

Marked hypoplasia affecting both dentitions is observed in cases of oculo-dental-osseous dysplasia. In cases of TURNER DOWN syndrome….

3. enamel hypoplasia of local and general acquired causes: dysplasias and dysmorphias

Many diseases can be responsible for enamel hypoplasia and hypocalcification, which vary depending on the period of involvement in relation to amelogenesis.

In fact, any systemic disease of the pregnant mother or young child, any significant failure of the organism can leave a signature on the enamel.

Fluoride poisoning or abnormalities of phosphocalcic metabolism 

It is a chronic disease related to the long-term administration of very high doses of Fluoride: The colour of the teeth varies from yellow to dark brown with the characteristic appearance of the enamel which is dull plus chalky stains. 

Dentin abnormality

Dentinogenesis imperfecta (DI) and dentin dysplasia (DD) represent the clinical expression of dentin abnormalities. 

.1. Dentinogenesis imperfecta:

DI occurs either in isolation or in association with one of the forms of osteogenesis imperfecta (OI).

Coronal wear is more or less intense, The general coloring is amber, translucent. The enamel is fragile.

2. Dentin dysplasia:

Coronal dentin dysplasia:

It is characterized by the involvement of baby teeth, which are amber and translucent in color. Permanent teeth have a normal color. The histological structure of the dentin is very anarchic. 

 Cementum anomalies:

Cementum hypo or aplasia:

Of radiographic discovery.

Affects temporary teeth , especially anterior ones.

Usually before the age of three.

It is a defect in the deposition of cellular cementum on acellular cementum.

Cementicle:

Spherical calcified nuclei that develop within fibrovascular elements. 

Usually located inter-radicular, they can be found within the cementum layer or the alveolar bone.

Dental Anomalies

Hypercementosis:

Mainly affects the mandibular molars.

Mainly apical in location.

May hinder tooth eruption, cause root bends and lead to ankylosis.

6. Volume anomalies:
7. True (absolute) volume anomalies

Tooth size is genetically determined, but can be affected by other factors.

True generalized macrodontia: or dental gigantism is extremely rare, it affects all teeth and has been associated with pituitary gigantism. 

True localized macrodontia: this may involve macrodontia of a tooth and its symmetrical counterpart, as it may involve unilateral macrodontia, as it may affect only the root: this is rhizomegaly. 

True generalized microdontia 

Or dental dwarfism (or microdontism) is rare, it is sometimes associated with dwarfism of pituitary origin. 

True localized microdontia: localized to one or more teeth, it is common, it mainly concerns the teeth at the end of the series which are also among the most agenetic teeth. In the case of unilateral cleft palate, the permanent teeth are often smaller than their counterpart on the healthy side.

It can be found in the context of certain genetic syndromes: Mohr, Goltz, Williams syndrome, etc.

Radicular dwarfism or rhizomicria is found in the premolars and third molars. 

Dental Anomalies

5. Conclusion

The problem of dental anomalies is not specific to orthodontics but a large number of them have orthodontic repercussions.

A significant number go unnoticed when they are installed.

Careful observation of the teeth and jaws allows them to be detected early and appropriate treatment to be carried out. 

Dental Anomalies

  Wisdom teeth can be painful if they are misplaced.
Composite fillings are aesthetic and durable.
Bleeding gums can be a sign of gingivitis.
Orthodontic treatments correct misaligned teeth.
Dental implants provide a permanent solution for missing teeth.
Scaling removes tartar and prevents gum disease.
Good dental hygiene starts with brushing twice a day.
 

Dental Anomalies