Thumb sucking is defined as placement of the thumb or one or more fingers in varying depths into the mouth. Some children instead of sucking the thumb have the habit of finger sucking. The thumb sucking habit is considered normal in preschool children but it is considered abnormal when the child continues with the habit even after the preschool age. Then this habit is called as pernicious thumb sucking habit. Pernicious means this habit interferes with the normal development of the orofacial structure. The front teeth start coming out. The upper arch becomes narrow and child may develop open bite.

How much a particular habit can affect the dento facial structure depends upon the three factors

Duration i.e. for how long the particular habit is practiced.

Intensity i.e. how intensely the particular habit is practiced. In case of thumb sucking some children suck the thumb very vigorously but some children just keep the thumb in the mouth and do not suck it. The thumb sucking habit becomes more harmful if the child sucks the thumb intensely.

Frequency  i.e. how often the particular habit is practiced. Some suck the thumb only at night, while others suck the thumb whenever they are free. With increased frequency the habit becomes more harmful.

Types of Thumb Sucking

Depending upon how much thumb is placed in the mouth the thumb sucking habit is

Type A – This type of thumb sucking is seen in 50% of cases. In this the whole thumb is placed in the mouth with pad of the thumb pressing the vault of the palate. The upper and the lower teeth make contact with the thumb.

Type B – This type of thumb sucking is seen in 13-24% cases. The thumb makes contact with the palate and the upper and lower teeth.

Type C – This type of thumb sucking is seen 18% of cases where thumb is placed in the mouth just beyond the first joint. The thumb makes contact with the hard palate and the upper teeth. The lower teeth do not touch the thumb.

Type D – This type of thumb sucking is seen in 6 % of cases where only anterior part of the thumb is placed in the mouth.

Reasons or Causes of Thumb Sucking

There are various theories given to explain the habit of thumb sucking. One theory is given by Sigmond Freud which is called as psychoanalytical or psychosexual theory. According to this theory the habit is continued as the manifestation of an underlying psychological disturbance.

There is another theory called as Oral Drive Theory given by Sears and Wise. According to this theory prolongation of nursing strengthens the oral drive and the child starts with the thumb sucking. But the Learning theory says that habit stems from an adaptive response. There is no underlying psychological cause. It is acquired as a result of learning.

We divide the causes of thumb sucking into two:

  1. Psychological:  It is said that child starts thumb sucking because he feel insecure, lonely or stressed. There is some underlying psychological reason for thumb sucking.

  2. Habitual:  Sometimes it is just the habit. May be initially there is some reason but after wards it just becomes the habit to suck the thumb.


Leave Comment

Free Dental Consultation