Dental agenesis

 Dental agenesis

           Introduction :

• Anomalies constitute an irregularity, a deviation from what is normal.
• The dental system is defined by standards that concern the shape of the teeth, their location on the arch and their number, hence dental agenesis which manifests itself by a reduction in the number of teeth.
• Research, particularly in the field of genetics, has enabled immense progress in understanding the origins and development of the dental system.

1. Definition :

It is a numerical anomaly corresponding to the absence of a dental unit in relation to the absence of the corresponding germ

Can affect one or more teeth, can be unilateral or bilateral and concerns permanent teeth, it can also be associated with agenesis of temporary teeth.

2. Frequency :

• Affects 6-7% of the population 
• Affects the so-called “end of series” teeth: Lateral incisors, second premolars and the DDS
• The ranking of agenesis in order of frequency is:  

      – Upper and lower DDS

      – Lower second premolars

      – Upper lateral incisors.

3. Different types of dental agenesis:

• Unilateral or bilateral agenesis:

Unilateral agenesis constitutes ¾ of cases and is frequently associated with microdontia or abnormal shape of the contralateral tooth.

• Multiple agenesis:

• Hypodontia: reduction in the number of teeth (1 to 5 teeth)
• Oligodontia: absence of a large number of teeth (06 teeth and more), it can be:

• Isolated, that is to say not associated with other manifestations,
• Associated with other manifestations in the context of certain syndromes ( ectodermal dysplasias ).
• Anodontia: total absence of all temporary and permanent teeth due to complete agenesis. It is always syndromic (extremely rare).

   There may also be abnormalities of size (smaller teeth) and shape (conical teeth, taurodontism) as well as enamel abnormalities and delayed eruption of existing teeth.

4. Etiologies:

• Genetic cause:

• Phylogenetic etiology: genetic adaptation to increasingly soft food, responsible for atrophy of the jaws by reduction in the number of teeth
• Genetic diseases: accompanied by dental agenesis e.g.: ectodermal dysplasia, trisomy 2, cleft lip and palate
• Transgenerational agenesis: agenesis of the same tooth is found in members of the same family
• Transmission of a dominant gene.
• Environmental cause:

Local disturbances affecting the developing fetus (vitamin deficiencies, emotional shocks, medication intake) could be the cause of the absence of tooth germ formation.

5. Diagnosis:
   1. Interrogation  : looking for:

• Detecting a family predisposition
• Eliminate the possibility of tooth extraction

2. Clinical examination:

• Persistence of the temporary tooth without malposition of the neighboring teeth, the contralateral tooth is present on the arch.
• Infra position of the temporary tooth (2nd ^temporary molar)
• Absence of the permanent tooth after induced elimination of the temporary tooth.
• Persistence of the 2 temporary teeth in case of bilateral agenesis after the normal date of eruption of the corresponding permanent teeth taking into account the dental age of the subject.

Dental agenesis

5.3 Radiological examination:

• Panoramic X-ray:
  • Allows the absence of the germ to be noted after the normal date of eruption.
  • Allows you to assess the condition of the roots of the corresponding temporary teeth.

6. The consequences:

• Agenesis is an aesthetic problem (anterior teeth).
• Mental problems in adolescents
• Problem with phonation
• In case of multiple agenesis: chewing problem, poor digestion, digestive system disorders

Conclusion:

• The aim of orthodontics is to create the optimal conditions for the correct establishment of adult teeth, always considering each case as unique.
• The role of the orthodontist is therefore:

     – Monitor, prevent and correct

     – Prevent the causes of the installation of dysmorphoses

     – Correct dental anomalies

                                                Dental inclusions

Introduction :

               In orthodontics, inclusion is a complex but relatively frequent situation.

               It is important to take into account the child’s dental age, in order to differentiate between delayed eruption, which most often affects the entire dentition, and inclusion, which affects an isolated tooth earlier.

1. Definitions:

• The included tooth:

It is a tooth retained in the maxilla beyond the normal date of eruption without communication with the oral cavity and without eruptive potential, the root being edified.

• Retained tooth: 

   It is a tooth prevented from its normal development, as long as it retains a developmental potential, without communication with the oral cavity. Retention results in the maturation of the tooth at inclusion.

• An impacted tooth:
      This is a tooth retained in the maxilla beyond the normal date of its eruption and whose pericoronal sac is open in the oral cavity, the eruption process allows it to evolve without reaching the occluso-functional relationship.

2. Frequency :

• Adult teeth are at risk of inclusion in order of frequency:

DDS inf, DDS sup, upper canines (20 times that of lower canines), central incisors, lower second premolars

•  Canines in palatal (50%), vestibular (30%), intermediate (20%) position.
• Slight prevalence in girls. 
• Inclusion can be unilateral or bilateral.

3.  Etiopathogenesis:

• General causes:

Although local causes are most often the cause of inclusion, hereditary factors can play a predisposing role while being closely linked to the effects of the surrounding environment.

• Hereditary and congenital factors:

• Family predisposition
• Major syndromes
• Endocrine, vitamin, nutritional factors and infectious diseases:

– Endocrine disorders: hypothyroidism leads to delayed growth and rash

• Vitamin deficiencies: A, D, C
•  infectious diseases: tuberculosis
• Regional causes:

• DDM: by reducing space promotes eruptive disorders and the risk of inclusions
• Skeletal etiologies: Brachymaxillary
• Dental etiology: macrodontia

• Local causes:
• Tooth germ:

• Developmental abnormality: pulp, periodontal atrophy
• Situational anomalies: premature extraction of temporary teeth 
• Shape abnormality: coronal or radicular dysmorphisms (insufficient straightening of the germ)
• Germ environment:

• Trauma: deviated eruption path, partial destruction of the follicle 
• Obstacles: odontomas, cysts, supernumerary teeth, non-resorbable filling paste of the temporary tooth
• Abnormalities of temporary teeth: ankylosis, retention, number, size, shape and premature loss
• Ankylosis: fusion of cementum with bone
• Thick and keratinized fibromucosa or hypertrophied frenulum

4. Diagnosis:

• Must be done as early as possible in order to monitor progress and implement appropriate therapy
• The consultation is carried out very early in the absence of a central incisor (unaesthetic and asymmetrical situation)
• In the case of canines, the consultation is late because no functional or aesthetic signs are apparent, therefore a fortuitous discovery.

4.1. Anamnesis

• Family predisposition
• Pathological and dental history as well as possible contraindications to surgical-orthodontic treatment
• Understanding the patient’s motivation when faced with long and difficult treatment.

      4.2 Clinical examination:

• Exoral examination:

• The signs are rare and discreet
• Examination of the ATMs in search of various disorders (cracking, clicking, popping) in relation to mandibular kinetics disturbed by the absence of canine protection or incisal guide.

Dental agenesis

• Intraoral examination:

Inspection:

• Absence of permanent tooth after normal eruption date
• Late persistence of temporary tooth
• Decrease in the space on the arch required for eruption
• Important DDM
• Importance and level of insertion of the labial frenulum.

Dental agenesis

Palpation:

• Search for a painless, incompressible palatine or vestibular fibromucous arch
• Study of the mobility of the temporary tooth and adjacent teeth in search of rhizalysis
• Painful palpation, inflamed mucosa indicates the presence of complications

4.3. Radiological examination:

– Used to confirm suspicion of inclusion

– Allows to determine the possibility of treatment

• Intraoral investigations: 

– Retroalveolar: 

Gives a very precise image of the morphology of the tooth, its relationships with the surrounding structures, follicular sac, desmodontal space

– Occlusal films:

Large film placed in the occlusion plane horizontally allowing visualization in 2 spatial planes: AP and transverse 

• Extraoral investigations: 
•  Panoramic X-ray: 

• Performed as a first-line procedure in the event of suspected inclusion
• Allows an overview of the dental arch and bony structures
• Provides information on the inclusion height , general axis of the tooth, its vicinity
• Disadvantage: does not allow palatal or vestibular localization
• The lateral teleradiography:

• Information on vertical and AP plans
• Position, Direction, Height of Inclusion
• Cone beam:

     This is the examination of choice, allows the detection of the position of the included tooth and its relationships with neighboring structures and to carry out distance measurements between the different structures.

     4.4 Differential diagnosis:

• Dental agenesis: the tooth cannot be objectified by radiological examinations
• Retained teeth – Impacted tooth
• Delayed eruption: depending on dental age
• Iatrogenic avulsion

5. Accidents and complications:

• Mechanical accidents:
• Gingival ulceration, weakening of the mandibular angle (DDS), root rhizalysis of neighboring teeth, dental articulation disorders, worsening of a pre-existing overlap
• Nervous accidents and reflexes:

• Pain, aches
• Vasomotor disorders (tearing)
• Eye disorders
• Hearing problems, ringing
• Fronto-parietal alopecia
• Infectious accidents:

    Peri coronaritis, subperiosteal abscess, cellulitis, osteitis

• Tumor accidents: granulomas, cysts
• Prosthetic accidents : destabilization of prosthesis

Conclusion :

   Inclusion is a common situation in orthodontic practice, however, the practitioner must know:

• The causes of inclusion
• Position of the included tooth

This is thanks to a rigorous clinical examination supplemented by a quality radiological examination to arrive at a good diagnosis and consequently a well-conducted treatment which generally involves multidisciplinary collaboration as well as the cooperation of the patient. 

Dental agenesis

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Preventative dental care avoids costly treatments.
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Fluoride mouthwash strengthens tooth enamel.
An annual checkup helps monitor oral health.
 

Dental agenesis