Thumb Sucking

Thumb sucking or finger sucking is the most prevalent oral habit in children today. Learn more about it and how you can eliminate it.

Thumb and Finger Habits

Digit sucking
Problems encountered with thumb sucking

Thumb and finger habits make up the majority of oral habits. About two thirds are ended by 5 years of age (Helle and Haavikko, 1974). Dentists ore often questioned about the kinds of problems these habits may cause if they are prolonged. The malocclusion caused by non-nutriative sucking may be more of an individual response than a highly specified cause-and-effect relationship (Baril and Moyers, 1960). The types of dental changes that a digit habit may cause vary with the intensity, and frequency of the habit as well as the manner in which the digit is positioned in the mouth. Intensity is the amout of force that is applied to the teeth during sucking. Duration is defined as the amount of time spent sucking a digit. Frequency is the number of times the habit is practiced throughout the day. Duration plays the most critical role in tooth movement caused by a digit habit. Clinical and experimental evidence suggests that 4 to 6 hours of force per day are probably the minimum necessary to cause tooth movement. Therefore, a child who sucks intermittently with high intensity may not produce much tooth movement at all, whereas a child who sucks continuously for more than 6 hours can cause significant dental change. The most common dental signs of an active oral habit are reported to be the following:

  • Anterior open bite
  • Facial (forward) movement of the upper incisors and lingual (backwards) movement of the lower incisors.
  • Maxillary (upper jaw) constriction

Anterior open bite, the lack of vertical overlap of the upper and lower incisors when the teeth are in occlusion, develops because the digit rests directly on the incisors. This prevents complete or continued eruption of the incisors, whereas the posterior teeth are free to erupt. Anterior open bite may also be caused by intrusion or pushing the incisors back into the bone. Inhibition of an eruption is easier to accomplish than true intrusion, however , which would be the result of a habit of great duration.

Faciolingual (foreward and backward) movement of the incisors depends on how the thumb or finger is placed and how many ar placed in the mouth. Some consider this positional variable to be a confounding factor related to intensity, duration, and frequency. Usually a thumb is placed so that it exerts pressure on the lingual or inner surface of the maxillary (upper) incisors and on the facial or outside surface of the mandibular (lower) insisors. A child who actively sucks can create enough force to tip the upper incisors facially (to the front) and the lower incisors lingually (to the back). The result is an increased overjet (horizontal distance between the tips of the upper and lower incisors) and decreased overbite (vertical distance of overlap between upper and lower incisors).

The constriction of the maxillary arch (roof of the mouth) is probably due to the change in equilibrium balance between the oral musculature and the tongue. When the thumb is placed in the mouth, the tongue is forced down and away from the palate. The facial muscles found in the cheeks which include the buccinator and orbicularis oris exert a force on the maxillary teeth. This causes them to be pushed inward, especially when the muscles are contracted during sucking. Because the tongue doesn’t exert a counterbalancing force the posterior maxillary arch collapses into crossbite.

Timing of treatment must be gauged carefully. If parents or the child do not want to engage in treatment, it should not be attempted. The child should be given the opportunity to stop the habit spontaneously before permanent teeth erupt. If treatment is selected as an alternative, it is generally undertaken between the ages of 4 and 6 years. Delay until the early school age years allows for spontaneous discontinuation of the habit by many children, often through peer pressure at school. As long as the habit is eliminated prior to full eruption of the permanent incisors, the eruption process will sponenously reduce the overjet (horizontal distance between the tips of the upper and lower incisors) and open bite as the permanent teeth occupy new positions.

It is generally agreed that interception of a finger sucking habit does no harm to the child’s emotional development, nor does it result in habit substitution. The dentist should, however, evaluate the child for psychological overtones prior to embarking on elimination of the habit. Such procedures might best be postponed for children who have recently undergone stressful changes in their lives, such as changing schools, moving to a new community, or the separation and divorce of parents. Four different approaches have been advocated, depending on the willingness of the child to stop the habit.

  • Counseling with the patient
  • Reminder therapy
  • Reward system
  • Adjunctive therapy that includes a method to physically interrupt the habit and remind the patient

 

Counseling the Patient

The simplest, yet least widely applicable, approach is counseling sessions with the patient. This involves discussion between he dentist and the patient of the problems created by non-nutritive sucking. These adult-like discussions focus on the changes that have occurred because of the sucking and their impact on esthetics. This approach is best aimed at older children who can conceptually grasp the issue and who may be feeling social pressure to stop the habit. Some children are captured by this approach and successfully eliminate their habit.

 

Reminder Therapy

Reminder therapy is appropriate for those who desire to stop the habit but need some assistance. The purpose of any of these treatments should be thoroughly explained to the child. An adhesive bandage secured with waterproof tape on the offending finger can serve as a constant reminder not to place the finger in the mouth. The bandage remains in place until the habit is extinguished. Some clinicians have used a mitten or sock to cover the fingers of the hand. This is especially useful during sleeping hours. Another approach is to paint a commercially available bitter substance on the fingers that are sucked. All these methods are aimed at reminding the child not to place the fingers in the mouth. Sometimes this type of therapy is perceived as punishment, however, and may not be as effective as a neutral reminder.

 

Reward System and Adjunctive Therapy

In a reward system, a contract is drawn up between the child and the parent or between the child and the dentist. The contract simply states that the child will discontinue the habit within a specified period of time and in return will receive a reward. The reward does not need to be extravagant but must be special enough to motivate the child. Praise from the parents and the dentist plays a large role. The more involvement the child takes in the project, the more likely the project is to succeed. Involvement may include placing smiley faces on a calendar when the child has successfully avoided the habit for an entire day. At the end of a specified time period, the reward is presented with verbal praise for meeting the conditions of the contract. Reward system and reminder therapy can be combined to improve the likelihood of success. If the habit continues to persist after reminder and reward therapy and the child truly wants to eliminate the habit, adjunctive therapy that included a method to physically interrupt the habit and remind the patient can be used. This type of treatment usually involves either wrapping the patient’s arm in an elastic bandage so it cannot be flexed and the hand inserted in the mouth, or placing a dental appliance in the mouth that physically discourages the habit by making it difficult to suck a thumb or finger. The dentist should explain to the patient and parent that the appliance is not punishment but rather a permanent reminder not to place the finger in the mouth.

The elastic bandage method is usually applied only at night. The bandage is loosely wrapped over the arm extending from below the elbow to above it. The sheer mass of elastic material (not the tightness) prohibits the child from sucking the fingers. Success over several weeks should be rewarded. The total program may take 6 to 8 weeks.

An intraoral appliance approach can also be employed in the adjunct method. The two appliances used most often to discourage the sucking habit are the quad helix and the palatal crib. The quad helix is a fixed appliance commonly used to expand a constricted maxillary arch; a common finding accompanied by posterior crossbite in non-nutritive sucking patients. The helices of the appliance serve to remind the child not to place the finger in the mouth. The quad helix is a versatile dental appliance because it can correct a posterior crossbite and discourage a finger habit at the same time.

The palatal crib is designed to interrupt a digit habit by interfering with finger placement and sucking satisfaction. The palatal crib is generally used in children in whom no posterior crossbite exists. It may also be used as a retainer after maxillary expansion with a quad helix in a child who has not stopped sucking with the quad helix. Parents and the child should be informed that certain side effects appear temporarily after the palatal crib is cemented. Speaking, eating, and sleeping patterns may be altered during the first few days after appliance therapy. These difficulties usually subside within a few days to a couple of weeks. An imprint of the appliance usually appears on the tongue as an indentation and disappears soon after the appliance is removed. One of the main problems with a palatal crib and quad helix is maintaining good oral hygiene. The appliance traps food and is difficult to clean thoroughly. Oral malodor and tissue inflammation can result.

Adjunctive habit discouragement appliances should be left in the mouth for 6 to 12 months as a retainer. The palatal crib usually stops the child from sucking immediately but requires at least 6 months extra of wear to eliminate the habit completely. The quad helix also requires a minimum of 6 months of treatment. Three months are needed to correct the crossbite, and 3 months required to stabilize the movement.

 

References:

Halle A, Haavikko K: Prevalence of earlier sucking habits revealed by anamnestic data and their consequences for occlusion at the age of eleven. Proc Finn Dent Soc 70:191-196, 1974

Pinkham JR: Oral Habits. Pediatric Dentistry- Infancy Through Adolescence 393-401, 1999