The infant-sucking instinct is essential for survival and can start in the womb. Sucking fixations in infancy provide stimulation that is essential and normal for a baby’s growth and development. Thumb and/or finger sucking can help infants adjust to their new world. The behaviour allows infants to gain a sense of control, calm and soothe themselves, and shut out undesired stimuli. This soothing and calming effect also helps them fall asleep.
Thumb and/or finger sucking can start anytime in infancy and toddlerhood and parents shouldn’t be too concerned about their infant or toddler’s sucking behaviour at this stage. Most young children stop the habit on their own by the age of three or four. Some children, however, continue to suck after this age. A prolonged sucking habit is a cause for concern for a number of reasons. From the age of four onwards, a prolonged sucking habit can have a negative impact on a child’s dental and facial growth and development.
There is abundant research that describes the harmful effects of a prolonged sucking habit on dental growth and development. Just as controlled pressures of orthodontic appliances can move teeth, the pressures applied by a thumb or finger can influence the position of the teeth and the formation of the bony structure of the mouth.
The pressure of the thumb or finger/s against the upper front teeth or bone can cause the teeth or entire upper front bony structures to develop forward, creating an overjet. Children who have protruding front teeth can experience twice the dental trauma and fracture to these teeth than children who do not have an overjet. If the protrusion of the front teeth is significant, it becomes difficult to bring the lips together, resulting in an open mouth resting posture.
A prolonged and vigorous sucking habit can create a space between the upper lower front teeth, even when the jaw is closed, known as an open bite. This can prevent a child from developing a mature swallow pattern. A mature swallow evolves with normal growth and development, with the tongue moving upwards to create a seal between the tongue and the roof of the mouth. An anterior open bite forces a continuation of the forward thrusting of the tongue – infantile swallow – because the tongue has to seal off the gap between the upper and lower front teeth in order to create enough pressure for the child to swallow.
Prolonged thumb and/or finger sucking can also affect and change tooth position and proper development of the mouth leading to crowding and increased need for orthodontics in future. The developing palate in a child is malleable and is critical in a child’s craniofacial development. A developing palate can be easily deformed by prolonged pressures from the thumb or finger-sucking. The pressures from the cheeks during sucking, further narrow the developing palate contributing to narrow dental arches which can result in crossbite and open bites of the back teeth. The intrinsic muscles of the tongue that normally would position it on the palate fail to develop properly and can contribute to the child having changes in their lip structure, speech and breathing and swallowing functions.
The more frequently and vigorously the thumb or fingers are sucked, the more a child’s dental and facial growth and development are altered.
So yes…breaking the habit of thumb sucking is important if it is prolonged past the age of four years. Breaking the habit can take time and effort. Your Dentist or Oral Health Therapist can support you and your child through this transition.
