The first permanent molar in children
1. Introduction
Molar occlusion, particularly that of the first permanent molars, plays a fundamental role in both children and adults. The first permanent molar, also called the “six-year tooth,” is generally the first permanent tooth to appear in children. The first permanent molars, in each arch, are placed behind the temporary dentition and between them, the permanent dentition will be established. They will play a major role in the establishment of harmonious dentition in all three spatial directions. The appearance of this tooth is an event from a physiological and functional point of view. The first permanent molar is particularly prone to caries in young children.
2. Morphologies 2.1 Complex occlusal anatomy:
“100% of occlusal caries begin at the bottom of a fissure”
Crevices are plaque retention factors. These retention areas represent a reservoir for food debris and bacteria. In addition, they escape self-cleaning and the buffering power of saliva. They are difficult to brush and are not affected by the fluoride contained in toothpaste.
2.2. Occlusal anatomy of the maxillary first permanent molars :
On this occlusal face we find 4 cusps; 3 grooves; 3 dimples and 2 marginal ridges.
For the cusps , there are four of them: 2 vestibular cusps; 2 palatal cusps.
- The strongest of the 4 cusps is the mesiopalatine then the vestibulo-mesial; the vestibulo-distal and finally the disto-lingual.
- The set of these two cusps; palato-mesial and vestibulo-distal, is called the enamel bridge.
- The other two cusps are separated from each other by the enamel bridge.
For the furrows : 3 inter-cuspal furrows; vestibulo-central, mesio-central and disto-palatal.
For dimples 3 dimples: 2 main ones:
- The mesial dimple and the distal dimple and a lesser dimple
- The central dimple placed at the intersection of the furrow
- mesiocentral intercuspid and the intercuspid groove
- vestibulo-central
For the crests ; two crests
- A mesial marginal ridge and a distal marginal ridge.
The first permanent molar in children
The roots ; the upper molar has 3 roots;
- Two vestibular; and one palatine
- The most robust of the 3 is the palatine root
- then the vestibulo-mesial root
- and the smallest being the vestibulo-distal root.
2.3. Occlusal anatomy of the mandibular first permanent molars:
It has a hexagonal outline and carries 05 cusps. The 02 lingual cusps are conical and pointed. They are the largest in terms of height and mesio-distal diameter.
Next come, in descending order: the mesio-vestibular cusp, the central cusp and the disto-vestibular cusp.
The mesial marginal ridge is higher, long and prominent. The distal marginal ridge is low and short. The 02 marginal ridges converge towards the lingual surface.
The central fossa occupies a large area of the occlusal area. It is located in the center of this area; it is almost circular and shallow.
The mesial fossa is triangular and deep. The distal fossa is triangular but shallow.
We also find:
- 03 secondary grooves: the mesio-vestibular groove, the disto-vestibular groove and the lingual groove
- A main mesio-distal groove.
The first permanent molar in children
3. Physiological characteristics of the immature first permanent molar:
PMPI has several physiological characteristics that make it particularly cariosusceptible: tissue maturity, posterior position on the arch, anfractuous anatomy, as well as the temporality of its eruption.
4. Reminder of histology 4.1. The immaturity of histological tissues
Immaturity of the enamel: Immature enamel does not have a smooth surface; enamel development occurs in an “onion skin” fashion during the apposition phases forming the Rietzius striae. Perikymatia are very fine grooves, resulting from the emergence of striae on the surface of the enamel. The enamel has not yet undergone mineralization/demineralization cycles at the enamel/biofilm junction that contribute to the post-eruptive maturation of the tooth.
- As a result, these surface irregularities facilitate the adhesion of bacterial plaque, and therefore the initiation of the caries process.
4.2. Dentin immaturity: The characteristics of immature dentin are:
- – First, from the beginning of dentin edification until the end of rhizagenesis, the dentin produced is composed only of primary dentin. It will be only after the end of root edification of the tooth that the odontoblasts will produce secondary dentin. However, in response to an external aggression, there may be production of tertiary dentin, whether reactive or repair.
– Then , due to this single layer of primary dentin, the pulp volume is significant and there is no retraction of the pulp chamber at this stage in the absence of tertiary dentin. – Finally, during this maturation phase, the dentinal tubules are wide and 80% open in the deep areas at the level of the pulp ceiling and therefore very permeable.
Furthermore , the spread of dental caries is faster in dentin than in enamel, resulting in so-called “phantom” caries, or hidden caries; clinically there is no enamel cavity, while the dentin itself is already very affected. This delays visual diagnosis and therefore reduces the chances for the tooth
4.3. Pulpo-radicular immaturity : The nerve fibers complete their maturation when the tooth becomes functional. As a result, the sensitivity of the immature tooth is less, which implies unreliability of the thermal tests submitted to it, but also little or no pain in the case of a large and deep carious lesion.
5. The eruption:
During the eruption period of the PMPI, it is the last tooth in the dental arch in a very young child.
6. Location: of the immature first permanent molar: a high-risk most posterior situation
Very often, the beginning of its emergence goes unnoticed by both the child and his parents. Especially since PMP does not follow the loss of a temporary tooth.
It is difficult to brush properly.
7. Earliness of its emergence:
- Proper plaque removal is not always mastered. Knowing that parents are not always aware that this tooth appears so early, they will not necessarily pay particular attention to it and insist with their child on the importance of good brushing in this area.
8. A slow eruption :
Between the appearance of the first cusp tip and the functional occlusion of the 6, a significant period of time elapses, lasting on average 15 months.
During this period, the tooth is below the occlusal plane of the temporary molars and therefore difficult to access for brushing, but above all, it does not benefit from the self-cleaning due to chewing.
9. An atypical flora :
It would appear that there is a particular bacterial flora at the level of the first permanent molar before it is in occlusion, comprising a significant proportion of Actinomyces Israelli (whereas it is found in lower proportion on the molars in occlusion)
. Also, “other cariogenic bacteria than Streptococcus Mutans would be involved in the initiation of the carious process specifically on erupting molars”
. These would be S. Salivarius and S. Oralis found in large numbers at the level of the caries of the erupting molars.
10. Pathologies of the immature 1st molar :
10.1. Caries disease
10.2. Incisor-molar hypomineralization (MIH)
The main pathologies of the immature first molar
10.1. Caries disease: Dental caries is defined as an infectious, multifactorial, transmissible and chronic disease that causes demineralization of the hard tissues of the tooth (enamel, dentin, cementum). Localized destruction of dental tissues is the physical sign of this disease.
Tooth decay
The diagnosis of a carious lesion in immature permanent teeth is urgent.
- It is essential at all costs and as quickly as possible to stop the progression of caries and preserve pulp vitality (in order to allow physiological root development and promote harmonious development of the arches).
- The practitioner will have to explain to parents and children the factors that promote early caries, in the presence of bacterial plaque, poor brushing, and a diet rich in sticky and sugary products.
- Several parameters influence the early and rapid development of carious lesions in children:
10.2. Incisor-molar hypomineralization
MIH, Molars Incisors Hypomineralization, is a qualitative enamel defect, affecting at least one of the first four permanent molars, and may affect one or more permanent incisors.
The first permanent molar in children
- Enamel defects are clinically revealed by brown or chalky white spots, non-symmetrical opacities.
- Three degrees of MIH impairment are described:
– Light
o Opacity(ies) outside the occlusal surface,
o No loss of enamel from Easter areas,
o No hypersensitivity,
o No caries associated with affected enamel.
– Moderate
o Opacity(ies) on the occlusal surfaces,
o Post-eruptive fracture of the enamel limited to 1 or 2 faces (without cusp involvement),
o Atypical restorations,
o Normal tooth sensitivity.
Severe
o Extensive post-eruptive fracture of the enamel,
o Severe tooth sensitivity,
o Caries associated with hypomineralized enamel,
o Significant coronal destruction including the cusps, possible pulp complications,
o Multiple restoration failures.
11. Conservative therapy:
11.1. Preventive therapy
Prevention or primary prevention is the set of measures implemented to prevent a disease from taking hold.
When individual prevention is aimed at the child, it is the result of a partnership between three wills: that of the parents, that of the child, and that of the dentist.
Preventive action must address several of these factors:
11.1.1. Action on power supply;
• Implementation of appropriate oral hygiene;
• Strengthening of teeth by adding fluoride;
• Dental visits and professional preventive acts (Sealants).
- All foods that contain carbohydrates are potentially cariogenic. This means that the majority of foods and needs we take are cariogenic. Removing them from our diet is impossible, but we can modify some foods.
- Our action will focus on:
• Choosing a balanced diet;
• Avoid repeated intake of sugary drinks, or drinks with a low pH.
11.1.2. Implementation of appropriate oral hygiene
- The goal is to control dental plaque in quantity and quality.
11.1.3. Strengthening teeth by adding fluoride
Fluoride is a naturally occurring mineral and is considered an essential nutrient for the formation of healthy bones and teeth.
The three main mechanisms of action of fluoride are:
• Inhibition of demineralization of early carious lesions and promotion of remineralization with formation of less soluble enamel.
• Inhibition of glycolysis reducing the acidogenic potential of bacteria.
• Reduction of the solubility of enamel in acids by incorporation of fluoride into the hydroxyapatite crystal.
Fluoride can be absorbed in two ways, either topically or systemically:
• Topical mode consists of applying the substance to the external surface of the teeth. (For example: toothpastes, mouthwashes containing fluoride, gels).
• The systemic mode consists of the ingestion of fluoride. It then acts by attaching itself to the tooth during its formation.
11.1.4. Professional preventive actions: prophylactic sealing of grooves, pits and fissures “sealants”
Sealants are composites generally placed in the grooves of the first permanent molars (developing around 6 years old), possibly the second permanent molars (developing around 12 years old) in order to protect them, thus preventing the onset of carious processes.
12. Curative therapy
A truly conservative approach begins with diagnosis and assessment of caries risk in order to decide on the most appropriate treatments, taking into account the individual status of each patient.
Modern treatment plans incorporate control of caries disease, to prevent further lesions, delay initial fillings, and limit the size of cavities when loss of substance makes the placement of a restoration necessary .
Preserving original dental structures is the priority of modern dentistry, both medical and preventive.
13. CONCLUSION
- The first permanent molar plays a role as a guide for the permanent dentition. It controls the establishment of dental occlusion, participates in maxillary growth and in the physiology of the masticatory system.
- Our molars accompany us throughout our lives.
- Cavities in molars can be prevented. Prevention involves careful brushing, regular visits to the dentist, a healthy diet and, if necessary, fluoride supplements and preventive care at the dental office .
The first permanent molar in children
Sensitive teeth react to hot, cold or sweet.
Sensitive teeth react to hot, cold or sweet.
Ceramic crowns perfectly imitate the appearance of natural teeth.
Regular dental care reduces the risk of serious problems.
Impacted teeth can cause pain and require intervention.
Antiseptic mouthwashes help reduce plaque.
Fractured teeth can be repaired with modern techniques.
A balanced diet promotes healthy teeth and gums.