Primary teeth - Milk teeth

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Nutrition, Health & Wellness

Primary teeth - Milk teeth

Home › Sensitive teeth › Neonatal teeth › Primary teeth - deciduous, baby, temporary or milk teeth

The primary teeth or milk teeth are the first set of teeth to develop in infants. The primary teeth erupt and become visible in the mouth typically when the baby is about six months old. There are many exceptions, and teething in some babies may be delayed and start as late as 18th month. Some infants may be born with natal teeth and in some teething may start in the first month itself.
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In general, the primary teeth start erupting by about sixth month of age. It may take 30-36 months for the completion of eruption of all the primary dentition. In total, twenty milk teeth are formed, ten on the maxilla and ten on the mandible. The primary dentition is made up of two central incisors, two lateral incisors, two canines and two first molars and two second molars on each jaw. The child starts losing the milk teeth by the 6th year to be replaced by permanent dentition. The falling of primary dentition and their replacement may go on till 12-13 years of age.

Milk teeth development

The primary dentition start developing during the pregnancy. When the human embryo reaches sixth week of development, dental lamina is formed as an in-growth of oral ectoderm. The process starts in the midline and spreads to posterior region.

dental lamina and bud

By the time the fetus reaches eight weeks stage, ten dental buds are formed on the upper arches as well as the lower arches. These dental buds keep developing inside the gums and by the sixth month erupt out of the gums. Generally, the mandibular central incisors are the first milk teeth to appear. The maxillary second molars are the last to erupt.

Nutrition for milk teeth development

Calcium, phosphorus, vitamin A, vitamin C and vitamin D are essential nutrients for the proper development of healthy dentition. Dental enamel and dentin are composed of hydroxyapatite crystals and calcium and phosphorus are needed for their proper formation. Vitamin D regulates the availability of calcium. The deficiency of these minerals and vitamin D may result in less mineralization of hard structures.

Keratin and collagen are required in the developmental process. Vitamin A is necessary for keratin formation and vitamin c is essential collagen synthesis. The deficiency of vitamin A may affect enamel formation. Fluoride makes the structure resistant to demineralization and caries formation by getting incorporated into the developing hard tissues. Excess of fluoride during teeth development can lead to fluorosis.

Eruption of primary teeth

The central incisors erupt by 6-12 months and the lateral incisors emerge by 9-16 months. The mandibular incisors appear earlier than their maxillary counterparts. First molars emerge by 12-20 months and second molars emerge by 22-36 months. The canines appear by 15-24 months of age.

The importance of milk teeth

The appearance of milk teeth and their proper development is very important for the development of buccal cavity. The permanent dentition develop from the same dental germ. The development of the skill of chewing of food and speech require functional primary dentition. The jaw bones and muscles depend upon the milk teeth for developing proper dimensions and form of the dental arches for the emergence of permanent dentition. Early loss of primary incisors usually does not have effect on the later dentition. However the early loss of primary canines or primary molars may result in space loss for the permanent dentition.

Differences between the primary and permanent teeth

Though the internal anatomy is similar, the primary and permanent dentition differ in many aspects. The permanent dentition is larger in size. Premolars are present in the permanent dentition. The enamel in the primary dentition is less mineralized, thinner and more translucent. Due to thin layer of enamel caries can form easily. The pulp chambers are large and the roots small and narrow in primary dentition. The primary dentition is temporary and falls off to give place for the permanent one.

Caring for primary teeth

The sooner we start cleaning infant’s milk teeth, the better. Gums and milk teeth may be wiped clean with a clean warm soft moist cloth after feeds. Depending upon the number of erupted milk dentition, the baby may be introduced to daily brushing by 12-18 months of age. By the age of 2 years a visit to a dentist is recommended to know the health status of the primary dentition. The caries formed in the milk teeth may affect the health of the permanent dentition.

Caries prevention in milk teeth

Poor oral hygiene is the root cause of caries formation. Infants tend to fall asleep while breast-feeding or bottle-feeding. The last mouthful of milk may remain in the mouth if they were feeding in the lying position. The milk may decay and caries may develop. To prevent teeth decaying and also infections of the eustachian tubes and ear, infant's head must be at a higher elevation than the throat while feeding milk. It prevents milk from staying back in the mouth even if the baby falls asleep whilst feeding.

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References:
1.Alexander K. C. Leung and William Lane M. Robson. Natal teeth: a review. J Natl Med Assoc. 2006 February; 98(2): 226–228. PMCID: PMC2595049.

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Milk teeth are primary teeth.

Natal teeth - Neonatal teeth

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Natal teeth - Neonatal teeth

Home › Sensitive teeth › Neonatal teeth - Natal teeth

Natal teeth are present at the time of birth. Neonatal teeth grow after birth during the first month. Except for the time of appearance, there is not much difference between these teeth. Natal teeth are uncommon and one in every 2,000 to 3,000 infants may have them at birth. In some infants their presence may be associated with certain medical conditions.

Actually these teeth are primary deciduous dentitions, which have emerged very early. The most commonly affected are the lower central incisors. They usually occur in pairs. In very rare cases primary maxillary incisors or primary lower canines may be involved. In a few cases they may be supernumerary and get replaced by the true primary dentition. A dental roentgenogram can help in differentiating the supernumerary incisors.

Though the exact etiology is not clear, maternal health during pregnancy appear to predispose the fetus in developing this condition. Maternal exposure to infections, fever, trauma, hormones, chemicals and toxin can become causative factors.

The teeth may be smaller than the primary incisors and may appear conical and yellowish. The root may be absent or poorly developed. They have hypoplastic or hypomineralized enamel, irregular dentin and most of them are mobile. Some may have shell-like crown structure loosely attached to gingival tissue.

These teeth may interfere while feeding or breastfeeding. The nipples may get lacerated and become infected and painful. There is a great chance for the infant to hurt and damage the tongue leading to sublingual ulceration (Riga-Fede disease). If the incisors are wobbly and loose there is a risk of swallowing or aspirating them into lungs. In such situations their extraction may be considered by the dentist.

In some rare cases they may be associated with genetic disorders such as Ellis–van Creveld syndrome, Meckel-Gruber syndrome and Sotos syndrome. Natal teeth are also associated with congenital disorders like Hallermann–Streiff syndrome, jadassohn-lewandowsky syndrome (pachyonychia congenita), craniofacial dysostosis syndrome, steatocystoma multiplex, Wiedemann-Rautenstrauch syndrome and Pierre Robin syndrome.

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References:
1.Alexander K. C. Leung and William Lane M. Robson. Natal teeth: a review. J Natl Med Assoc. 2006 February; 98(2): 226–228. PMCID: PMC2595049.

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Dental sensitivity - What causes sensitive teeth?

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What causes sensitive teeth? Soft drinks and health effects > Sensitive teeth - causes

Tooth sensitivity (dentin hypersensitivity) is characterized by short, sharp pain caused from exposed teeth in response to stimuli, typically thermal (hot and cold), evaporation (cold air), tactile, osmotic or chemical (sweet or sour foods). Though teeth sensitivity can affect individuals of any age, it is more common in the age group of 30-40 years. Relatively more women are affected than men. The most affected teeth are canines and premolars of both the upper and lower arches equally.

Exposed dentin is the basic cause of sensitive teeth

To know clearly the causes of sensitivity, we should know the structure of tooth. Tooth consists of upper visible crown region and lower invisible root region inside the gum. A layer of enamel protects the crown region and cementum protects the root region. At the center is the region called pulp having soft tissues, blood vessels and nerves. In between the outer enamel/cementum layer and inner pulp is another layer called dentin. Dentin consists of microscopic dentinal tubules and integrally connected to pulp. The physiological reaction in either dentin or pulp affects the other. Odontoblasts are the major cell components of dentin and pulp. The extensions of odontoblasts called odontoblastic processes extend through the entire thickness of dentin from pulp to enamel and also occupy the dentinal tubules. Inside the dentinal tubules odontoblastic processes are surrounded by dentinal fluid which accounts for nearly 20% of dentin volume. Dentinal fluid is formed from pulp blood supply and is the communication medium between the outer regions of the dentin and pulp.

Tooth sensitivity is due to fluid movement and fluid force inside dentinal tubules. Not all exposed dentin cause sensitive teeth. There are wider dentinal tubules with no smear layers or thinner smear layers in sensitive dentin when compared to non-sensitive dentin. Pain or sensitivity perception is by the activation of dentinal nerve fibers (A-fibres) present on the pulpal wall. The stimuli activating these nerves are, rapid outward flow caused by capillary forces, contraction and outward flow due to cold and hydrodynamic flow caused by sweetness and sourness.

Causes leading to dentin exposure and sensitive teeth

The erosion of enamel and exposure of dentin may be due to a number of causes. Once the protective enamel or cementum are damaged pressure, temperature and other stimuli cause the teeth to become sensitive.

Poor oral hygiene
Poor oral hygiene causes food decay in the mouth and causes plaque and tartar formation on the teeth leading to caries, cavities, gum recession and dentin exposure.

Faulty tooth brushing
Brushing too hard erodes enamel and exposes dentin. Vigorous brushing, excessive forces and use of hard-bristled brush can erode the enamel and cause recession of gum tissue, exposing the underlying dentin .

Cracked or chipped teeth
Cracking and chipping of teeth exposes the dentin and causes bacterial infections.

Diseases of gum and teeth
Certain inflammations and diseases of gum like pyorrhea, gingivitis and periodontal diseases may cause sensitivity by exposing and damaging the dentin.

Erosive agents
Acidic foods like pickles, yogurt, sour tasting fruits and carbonated soft drinks can cause enamel erosion and expose the dentin. Some tooth whitening products and pastes and some mouth-washes can be acidic in nature and erode enamel. Exposure to stomach acids may occur in gastroesophageal reflux disease (GERD) and the enamel may get eroded.

Causes of teeth attrition
Attrition due to grinding of teeth affects teeth structure, initially affecting the enamel and then the underlying dentin. Once past the enamel, attrition can quickly destroy the softer dentin. The most common cause of attrition is bruxism. Normal functional actions like biting and chewing do not erode enamel.

Routine clinical procedures
Clinical procedures like cleaning, crown placement, filling, root canal treatment, orthodontics or restoration can cause temporary sensitivity which may last for 4-5 weeks.

Recent trends in management of tooth sensitivity

Foremost thing in the management of sensitive teeth is good oral hygiene. A soft bristled brush with a small head must be used to keep the gums healthy and prevent gums from recession. Brushing must be done in a small circular movement for each tooth without excessive use of force covering all the surfaces of the tooth. Highly abrasive tooth powder or pastes should not be used.

The sensitivity will persist unless the exposed open tubular apertures are sealed by a smear layer or any other sealant. In the management of sensitivity, the method used should not cause pain or irritation, should not stain the teeth and should be easy in application.
At-home treatments include desensitizing pastes, gels and chewing gums containing fluoride, strontium chloride, potassium citrate or potassium nitrate which have been found effective in the control of sensitivity.
In-office treatments at a clinic include sealants, fillings over the exposed roots and applying fluoride varnishes, sodium monofluorophosphate, fluorosilicates, sodium fluoride, stannous fluoride, potassium oxalate, conventional dentin bonding agents (DBA), hydroxyethyl methacrylate (HEMA), bioglass, calcium silicate cement, lasers, casein phosphopeptide or amorphous calcium phosphate.

By removing the etiological factors and causes and with proper treatment, occurrence and recurrence of sensitivity of teeth can be even prevented.

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Causes of sensitive teeth



References:
1.Miglani S, Aggarwal V, Ahuja B. Dentin hypersensitivity: Recent trends in management. J Conserv Dent 2010;13:218-24
2.Brännström M. Etiology of dentin hypersensitivity. Proc Finn Dent Soc. 1992;88 Suppl 1:7-13.