THUMB & DIGIT SUCKING :
• Digit Sucking is defined as the placement of the thumb/one or more fingers in varying depths into the mouth.
• It may be practiced even during intra-uterine (IU) life.
• Presence of this habit is quite normal till 3½ – 4 yrs.

ETIOLOGY:
A number of theories have been put forward to explain why thumb sucking occurs. The following are some of the accepted ones:

1. Freudian theory: This theory was proposed by Sigmund Freud in the early part of this century.
   • He suggested that a child passes through various distinct phases of psychological development of which the oral and the anal phases are seen in the first three years of life.
   • In the oral phase, the mouth is believed to be an oro-erotic zone.
   • The child has the tendency to place his fingers or any other object into the oral cavity.
   • Prevention of such an act is believed to result in emotional insecurity and poses the risk of the child diversifying into other habits.
2. Oral drive theory of Sears and Wise: Sears and Wise in 1950 proposed that prolonged suckling could lead to thumb sucking.
3. Benjamin’s theory:
   • Benjamin has suggested that thumb sucking arises from the rooting or placing reflex seen in all mammalian infant.
   • Rooting reflex is the movement of the infant’s head and tongue towards an object touching his cheek.
   • The object is usually the mother’s breast but may also be a finger or a pacifier.
   • This rooting reflex disappears in normal infants around 7 – 8 months of age.
4. Psychological aspects: Children deprived of parental love, care and affection are believed to resort to this habit due to a feeling of insecurity.
5. Learned pattern: According to some authors, thumb sucking is merely a learned pattern with no underlying cause or psychological bearing.

CLASSIFICATION:

EFFECTS :
The severity of malocclusion caused by thumb sucking depends on:

DURATION: Amount of time spent indulging in the habit.

FREQUENCY : The number of time the habit is activated in a day.

INTENSITY: Vigour with which the habit is performed.
The following are some effects:

1. Effects on Maxilla
   • Constricted maxilla due to lowered tongue position + buccinator action, while sucking.
   • V-shaped narrow palate.
   • Posterior cross-bite may occur.
   • Increased SNA angle.

2. Effects on Maxillary Teeth:
• Spacing in maxillary anterior teeth.
• Increased maxillary arch length.
• Labial flaring of maxillary anterior teeth.

3. Effects on Upper Lip :
• Short, hypotonic incompetent upper lip

4. Effects on Thumb:
• Presence of clean nails & callus on fingers.

5. Effects on the Lower lip:
• Hyperactive lower lip with increased mentalis activity.

6. Effects on the Mandibular Teeth:
• Retroclination of lower teeth.

7. Effects on Inter-arch Relationship:
• Increased overjet due to flaring of maxillary incisors
• Spacing of maxillary anterior teeth.
• Increased maxillary arch length.
8. Effects on Tongue:
• Lowered tongue position.
• Increased chance of developing tongue thrust habit.

MANAGEMENT:

1. PSYCHOLOGICAL APPROACH:
   • Parents should be counseled to provide child with adequate love, affection and spend quality time with the child.
   • Success of any habit interception largely depends on the subject’s willingness to be helped to discontinue his/her habit.

Dunlops Theory of Beta Hypothesis
States that the best way to break a habit is by conscious purposeful repititions, i.e the child should be made to sit in front of a large mirror &asked to observe himself as he indulges in the habit.

2. POSITIVE REINFORCEMENT:
   • Keeping track of the habit free days and rewarding the child can give the child a sense of pride.

3. MECHANICAL AIDS:
• Reminding appliances that assist the child who is willing to quit the habit but is not able to do as the habit has entered a subconscious level.
• Following types of habit louis used as mechanical reminding aids in treatment of thumb sucking.
REMOVABLE HABIT BREAKER
Passive removable appliances, that consist of a crib &is anchored to the oral cavity by the means of clasps on the posterior teeth.

FIXED HABIT BREAKER
Heavy gauge stainless steel wire can be designed to form a frame, that is soldered to bands in the molars.

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4. CHEMICAL APPROACH:

Use of the bitter tasting/foul smelling preparation placed on the thumb, that is sucked can make the habit distasteful.

• Pepper dissolved in volatile medium.
• Quinine
• Asafoetida

REFERENCES:

• ORTHODONTICS:The Art & Science,S.I BALAJHI (7th edition)

• dryasmin.ae