Examination of a thumb sucking patient by the dentist involves taking history from the patient and/or parents involving complete knowledge of behaviour,  habits and intensity of problem. It includes physical examination of the feature and intra oral examination of the patient. The complete process of this examination has been classified as under:

History  of the Patient

1.   Determine the psychological component involved

2.   Question regarding the frequency, intensity and duration of the habit.

3.   Enquire the feeding patterns, parental care of the child.

4.   The presence of other habits should be evaluated.

5.   The diagnosis of a digit habit can also be obvious when the child is actively performing the habit. However, during a dental appointment a child may seldom indulge in his habit. 

Extra Oral Examination

Various key areas to be noted include the following :-

The digits

Digits that are involved in the habit will appear reddened, exceptionally clean, chapped and with a short fingernail i.e. a clean dishpan thumbs. Fibrous roughened callus may be present on the superior aspect of the finger. The habit is also known to cause deformation of the finger.



Upper lip may be short and hypotonic. Note the position of lips at rest whether they are held together or apart. The position of the lips during swallowing should also be observed. Chronic thumb suckers are frequently characterized by a short, hypotonic upper lip. Relative tensions of the upper and lower lips also play a role during swallowing. Upper lip passive or incompetent during swallowing. Lower lip is hyperactive and this leads to a further increase in the proclination of upper anteriors due to its thrust on these teeth.

Facial form analysis

Check for mandibular retrusion, maxillary protrusion, high mandibular plan angle, and profile.

When swallowing, the patient is observed for presence of a facial grimace or an excessive mentalis muscle contraction, a normal placement of the tongue against the teeth and palate and whether the pattern of speech of the child is essentially normal. Facial profile is either straight or convex.

Other features

Features caused due to the presence of other habits along with thumb sucking. Associated symptoms that should be watched for during the initial examination are habitual mouth breathing and tongue thrust swallow, particularly in children with anterior open bite. Active thumb suckers also have a higher incidence of middle ear infections and frequently have enlarged tonsils accompanied by mouth breathing. Features of secondary habits have to be noted. 



Intra Oral Examination 


Examine the oral cavity for correct size and position of the tongue at rest, tongue action during swallowing.

Dento alveolar structures:

Individuals with serve finger or thumb sucking habits, where the digit applied an anterior superior vector to the upper dentition and palate, will have flared and proclined maxillary anteriors with diastemas and retroclined mandibular anteriors

Other intraoral symptoms will include a high probability of buccal crossbite, particularly in those children who suck their digits with a pronounced contriction of their buccal musculature and a tendency to narrow palates.

Observe the symmetry of incisal position of upper central and lateral incisors. Asymmetry indicates that the child sucks the right or left thumb or finger by preference. Measure dimensions of over-et and open bite if present.


Look for evidence of mouth breathing; gum line etching, decayed or excessive staining on the labial surface of the upper central and lateral incisors.

Clinical Findings:

A digit sucking habit can present without ill effects. However various malocclusions can occur in the primary and permanent dentitions.

The type of malocclusion produced by digit sucking is dependent on a number of variables (Nanda 1989)

1.   Position of digit.

2.   Associated orofacial muscle contractions

3.   Mandibular position during sucking 

4.   Facial skeletal pattern

5.   Intensity, frequency and duration of force applied.

Commonly Observed Clinical Problems:

Maxillary Anterior Proclination and Mandibular Retroclination.


When a child places a thumb or finger between the teeth, it is usually placed at an angle so that it presses lingually against the lower incisors and labially against the upper incisors. This direct pressure is responsible for the displacement of the incisors. There can be variation depending on which teeth are affected, how much, which teeth are contacted, and the number of hours per day of sucking and the magnitude of pressure. Intermittent vigorous sucking does not cause as much malocclusion as that seen in a habit of 6 hours or more, especially as seen in children who sleep with the thumb or finger between the teeth all night long.


The anterior open bite:    


This type of malocclusion arises due to a combination of factors. These are:


1.    Interference with normal eruption of incisors due to an interposed thumb.


2.    Excessive eruption of posterior teeth due to separation of the jaws, which alters the vertical equilibrium on the posterior teeth, 1 mm of elongation posterior, opens the bite by about 2mm anteriorly.


Constriction of Maxillary Arch:


This may be because of the failure of the maxillary arch to develop in width due to an alteration in the balance between cheek and tongue pressures. If the thumb is placed between the teeth, the tongue must be lowered, which decreases pressure by the tongue against the lingual surfaces of the upper posterior teeth. At the same time, cheek pressure against the teeth is increased as the buccinator muscle contracts during sucking. Cheek pressures are greatest at the corners of the mouth and this probably explains why the maxillary arch tends to become ‘V’ shaped with more constriction across the canines than the molars.


Posterior Cross Bite:


This occurs as a consequence of constriction of the maxillary arch. The unbalanced muscle forces on the maxilla exerted by the cheek muscles are unmet by the pressure from the lingual musculature which are normally present. While this results in a maxillary constriction, there is no restriction to the mandibular growth eventually leading to a cross bite. 


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  • dr ritz

    dr ritz 22 - December - 2011, at 23:40 PM

  • HM, By thumb sucking, forward movement of upper teeth and retrusion of lower teeth occurs. Along with this, anterior open bite, constriction of maxillary arch and posterior cross bite occurs in thumb suckers. Psychological component or feeding habits are responsible for thumb sucking habit. Changes in dental structures do encourage thumb sucking habit. For treatment of thumb sucking, firstly the root cause of thumb sucking is treated and then treatment is done for dental structures.

  • HM

    HM 22 - December - 2011, at 16:27 PM

  • So, the dental structures in a thumb sucker may form to encourage the habit, yes? By this I mean that the thumb sucking becomes more comfortable as a result of any movement thereby, correct?

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