Normal and Pathological Tooth Eruption

Normal and Pathological Tooth Eruption

1. Introduction

   Dental eruption corresponds to all the movements that a tooth makes, between the formation of the germ and its placement on the arch.

   Tooth eruption is a dynamic and complex biological and physiological process that occurs over several years and includes the formation of teeth and their migration in the jaws until their eruption into the mouth in the final functional position on the dental arches.

  The eruption of teeth is a physiological, natural phenomenon, both for the temporary and permanent dentition, which occurs at relatively fixed dates for each group of teeth, but can be disturbed and give rise to pathological accidents of varying importance.

Problematic

The various clinical and radiological manifestations observed during consultation

Goals

• Know and be able to identify its manifestations.
• Properly manage clinical cases causing real disruptions

What you need to know  :

• Dentition refers to all the phenomena concerning the formation, growth and eruption of teeth as well as their placement on the arch.
• The dentition is a static phenomenon which corresponds to the position of the teeth on the arch once the dentition phase is complete.
• It involves a transition between temporary teeth and permanent teeth.
• It is closely related to craniofacial development and growth.
• Eruption is a localized, symmetrical and programmed process, normally occurring simultaneously on both sides of the dental arch. It is regulated by the dental follicle and is accompanied by multiple tissue changes such as resorption.
• The first stages of development occur at the embryonic level and end about twenty years later with the eruption of the third permanent molars or wisdom teeth.
• The process of tooth formation and eruption includes several hypotheses that attempt to explain the mechanisms of eruption without, however, having completely elucidated them.
• Girls often have faster dental development than boys.

2. Physiology of normal dental eruption

    The description of normal eruption phenomena and their mechanisms allows for a
better understanding of pathological phenomena.

     Many theories of the eruption have been proposed but its mechanism
is still not well understood.

    II.1. Theoretical hypotheses explaining the phenomenon of the eruption:

          II.1.1. Unifactorial theory     a- Hypotheses related to desmodontal tissues         –   Collagen contraction: traction forces could occur within the network of desmodontal fibers during collagen maturation, leading to eruption.         –  Traction of desmodontal fibroblasts  :  The activity of fibroblasts (analogy with myofibroblasts) through their motility and contractility would be transmitted to the tooth in the form of traction via collagen fibers;         – Hydrostatic pressure exerted by tissue and vascular fluids: Driving role for internal osmotic pressures within the ground substance;           –  Root formation and cell proliferation: Rhizagenesis could generate sufficient force to cause tooth eruption 

           – Alveolar growth and the role of the follicle: Alveolar bone apposition, especially in the dental sac region below the tooth, could be the source of the eruptive force and the follicle could cause bone resorption above the crypt and apposition below. This determines an eruptive channel
II.1.2 Multifactorial theory  :   There is currently no incontrovertible proof of the unifactorial hypothesis. Therefore, eruption could be considered a multifactorial process; it could be: – A mechanism responsible for the appearance of forces capable of allowing the egression of the tooth; 

– a process by which such forces are transformed into eruption through movements through the surrounding tissues.
– a process that helps maintain eruption so that the tooth is held
in its new position;
– a remodeling of periodontal tissues to maintain the functional integrity of the system.

II.2. DESCRIPTION OF THE ERUPTION PHENOMENON a . Passive preclinical eruption or passive pre-eruptive phase – From the initial appearance of the dental germ until the beginning of root formation; – The germ appears to exhibit a concentric growth in its intraosseous site; – There is little axial movement; – In fact the germ does not move and there is bone apposition which gives the impression of movement. b-Active preclinical eruption – From the beginning of root formation until the crown breaks through the oral mucosa – The eruption rate varies from 1.2 mm/year for M3< to 3.5 mm/year for PM2<.- 

c- Pre-occlusal clinical eruption
– From the initial breakthrough to occlusion;
– The eruption speeds are the fastest: 1 to 2 mm/month.
–  Occlusal adaptation
– The two antagonist teeth enter into occlusion end to end then there will be
sliding along the cusp support pan of each tooth to end in occlusion in the central or marginal fossa or groove of the antagonist
support cusps

d- The clinical eruption of adaptation to wear
– After functional occlusion, axial or non-axial movements
can occur throughout life;

II.3. Eruption speed
– At any given moment, a tooth moves with a speed that represents a
balance between the forces tending to move it (eruptive forces) and the forces
tending to prevent its movement (resistance forces).
II.4. Rhizalysis
– Rhizalysis is the destruction of the roots of normal and
necessary temporary teeth. This is the main rule of diphyodontism;
– Theories on the factors causing rhizalysis of temporary teeth are
numerous, but it is normal to think that rhizalysis is created:
o by the contact of the pericoronal sac of the evolving permanent tooth;
o by the phenomenon of eruption.

3. Pathological dental eruption:

III.1. Chronological anomalies:
    The phenomenon of eruption of the two sets of teeth occurs at relatively fixed dates for each group of teeth, but can be disturbed and give rise to pathological accidents of varying importance. There may be precocity or delay in eruption.
    However, the dates of dental eruption are averages, even quite broad, which can vary without any particular pathological causes or consequences.
    Thus, it is considered that a variation of one month or one year can be taken into account depending on whether it is temporary or permanent teeth. We will therefore speak of early teething when the first temporary tooth appears before five months, and the first permanent tooth before five years (first molar).

a-Premature dentition  : We distinguish:
– Premature eruption : this is the presence of teeth at birth. This situation has no real pathological significance. It corresponds to anomalies of excess number, called pre-temporary dentition;
– Premature eruption , this is the appearance on the arch, before the normal date, of one or more well-formed teeth.

The origins are varied and depend on:

• Early eruption of all teeth is, however, very rare and is often linked to precocious puberty or hyperthyroidism.
• Gender: Tooth eruption is earlier in girls than in boys;
• Climate: Warmer climates appear to promote faster or earlier tooth eruption;
• The degree of urbanization: the eruption is faster in urban areas than in rural areas;     

b- Delayed teething:
  We speak of delay for the first dentition when it begins after ten months and, for the
second, after seven or even eight years. The anomaly can affect one or the other dentition or both at the same time.

If the delay in eruption is localized to a single tooth :   The cause is often local, it may be:

• Decayed and infected temporary tooth persisting on the arch;
• Healthy or missing temporary tooth; the X-ray will reveal the cause: supernumerary germ, tumor;
• Shape abnormality of the permanent tooth (curvature of the apex, large crown or root, etc.).
• An infection that can stunt growth at a given time during a general illness,
• Trauma to the maxillofacial region with immediate or long-term effects.

If the delay in eruption concerns one region or several teeth  : In this case, it is necessary to:

• Also consider the possible existence of a general cause (hypovitaminosis or avitaminosis, rickets, hypothyroidism, myxedema, previous acute general conditions, congenital syphilis).
• In major global delays, which are not very frequent, the cause may be related to nutritional deficiencies, vitamin D deficiency, endocrine disorders, infections

The delay in eruption may also be related to:

• Size  : Literature reports a relationship between reduced child size and dental delay;
• The jaws  : eruption is later in the upper maxilla than in the mandible;
• Posterior teeth  : The last teeth of each group (third molars, second premolars) are most frequently affected by delayed eruption;
• Dentition  : Delayed eruptions are rarer in temporary dentition than in permanent dentition;
• Population : There are differences in the timing of tooth eruption between populations. For example, European populations have a later eruption;
• Socioeconomic conditions  : children from a disadvantaged social background may have later dental development and eruption;
• Family rank : the eruption is later in the youngest born in a family than in the oldest.

III.2. Anomalies or eruption accidents:

    These are the complications or accidents of the eruption which are accompanied by a procession of various signs which affect both sets of teeth.

III.2.1 . Accidents of the temporary dentition:
    These are pathological, local, regional and general manifestations which precede, accompany or follow the eruption of the temporary teeth.

       The infectious theory allows us to understand the disorders of dental eruption: the accidents are due to an infection of the pericoronary sac, after permeability and breach of the gum.
      The reflex theory explains that irritation of the trigeminal nerve can reflexively cause the various remote manifestations. Hygiene and living conditions are contributing or aggravating factors.

a- Local signs:

• Gingivodental pruritus : The gingival mucosa is red and swollen; the child puts everything he has in his hand into his mouth and bites it hard. This is often a warning sign.
• Pericoronitis : The gums are swollen, painful, shiny. Pressure on them releases a drop of purulent serosity. A fever may accompany this pericoronitis .
• Erythematopultaceous stomatitis : this ulcerative stomatitis, with an aphthous or herpetic appearance, indicates a primary infection.
• A coronal-dental eruption cyst: This is the appearance of a small bluish submucosal pocket, a rounded fluctuating swelling containing a typical liquid, it contains the germ of the tooth.
                   

b- Regional signs:

• Redness of the face (or “toothburn”),
• Nasal discharge
• Tearing
• Hypersalivation.

c- General signs:

• Fatigue, insomnia, asthenia,
• Nervous disorders: convulsion, agitation,
• Digestive disorders: loss of appetite, diarrhea, vomiting,
• Respiratory problems: dry cough.

III.2.2 . Accidents of permanent dentition:

    Wisdom teeth are by far the teeth whose eruption is frequently accompanied by complications. In a young subject, any pathological manifestation in the angle region should draw attention to the possible evolution of a mandibular wisdom tooth. These accidents of evolution, generally benign, sometimes severe, can be summarized in four large groups: infectious, tumoral, mechanical, nervous

III.2.2.1. Infectious accidents  : They are always caused by an impacted or disimpacted tooth. They give rise to several clinical situations.
a- Mucosal accidents  : These may be 

• From pericoronitis  : It can be 

 Congestive, simple, causing quite sharp spontaneous pain in the retromolar region, otalgia, sometimes slight trismus.
Suppurative, causing the same clinical signs, but more pronounced and the presence of a hood which causes a purulent collection to emerge.
  Pericoronitis is the initial lesion, the first accident from which all the
others can arise. 

• From erythematous or ulcerative-membranous stomatitis , localized to the molar region, or more generalized

b- Cellular accidents:

   These are real abscesses or cellulitis can be due to the disinclusion of a mandibular wisdom tooth. The anatomy of the mandible conditions several situations: we can schematically classify these cellular accidents according to whether they evolve in different anatomical zones: outside the mandible and in front, outside the mandible and behind, inside and in front and behind.

c- Lymph node accidents : the lymph node system can be affected by the lymphatic route from the infection of the pericoronary sac, it is the painful inflammation of the lymph nodes and we can be faced according to the semiology with periadenitis, adeno-phlegmon.  

d- Bone accidents:

Bone complications are exceptional: these are osteitis due to the virulence of the germs and the patient’s immune deficiency.

III.2.2.2. Mechanical accidents: They can complicate the eruption of a wisdom tooth. You should think about them:

• Movements of teeth causing anterior crowding, a disturbance of the occlusion responsible for an impact on the temporomandibular joint 
• Distal caries and rhizosis of the distal root of the second molar, in contact with the wisdom tooth, observed by X-ray;
• An ulceration of the cheek mucosa, or a keratosis in the vicinity of the area of ​​eruption of the wisdom tooth;

.

III.2.2.3. Tumor accidents (marginal and lateral cysts)  : They form from the pericoronary sac.

• The posterior marginal cyst develops on the distal aspect of the crown of the lower DS and forms, on the radiograph, a clear crescent notching the ascending ramus.
• The anterior marginal cyst is located on the anterior surface of the crown of a lower DS in mesial version and forms a radiolucent crescent under the crown of this tooth.

III.2.2.4. Nervous and reflex accidents: they are:

• A symptomatic facial pain,
• Motor disorders such as certain paresis*, certain facial spasms, 
• A lockjaw, 
• Vasomotor and secretory disorders

Conclusion

Dental eruption is a physiological phenomenon that allows the positioning of teeth in the oral cavity in a functional position. Accidents of dental eruption are a frequent reason for our consultation. Eruption anomalies occur in both temporary and permanent teeth. It is necessary to distinguish between eruption accidents and chronological anomalies.

Normal and Pathological Tooth Eruption

  Early cavities in children need to be treated promptly.
Dental veneers cover imperfections such as stains or cracks.
Misaligned teeth can cause difficulty chewing.
Dental implants provide a stable solution to replace missing teeth.
Antiseptic mouthwashes reduce bacteria that cause bad breath.
Decayed baby teeth can affect the health of permanent teeth.
A soft-bristled toothbrush preserves enamel and gums.
 

Normal and Pathological Tooth Eruption