Eight out of ten children. That was the figure recorded at small clinics in six kindergartens in Wates District, Kulon Progo, when researchers began examining how the children swallowed. The result far exceeded their initial expectations: 80.21% of children who had lost all four crowns of their upper anterior primary teeth were found to have a habit of tongue thrusting, in which the tongue moves forward during swallowing—a pattern that should normally disappear by around the age of three.
The study, published in the December 2025 edition of the Jurnal Kedokteran Gigi Universitas Padjadjaran, is the first clinical study to directly demonstrate an association between the loss of upper anterior primary tooth crowns and the development of tongue thrusting in children aged 4–6 years. The research team consisted of drg. Suci Kurniawati, drg. Putri Kusuma Wardani Mahendra, M.Kes., Sp.KGA., and drg. Indra Bramanti from the Faculty of Dentistry, Universitas Gadjah Mada.
When the Tongue Searches for Its Missing Support
Tongue thrusting is not simply an insignificant bad habit. Clinically, the condition is characterized by predominantly forward tongue movement, with the tongue positioned between the upper and lower teeth during speaking and swallowing. In infants and children younger than three years, this pattern is considered normal as part of the primitive swallowing mechanism known as infantile swallowing. After the age of three, however, swallowing should have matured: the tongue should move upward to contact the palate rather than being pushed forward.
What happens in children whose front teeth have been destroyed by caries or trauma is anatomically logical yet clinically concerning. The anterior primary teeth function as a seal, providing a natural closure at the front of the oral cavity during swallowing. Once the crowns are lost, a gap resembling an anterior open bite develops. The tongue, with its remarkable capacity for adaptation, moves into this gap and takes over the role previously performed by the missing teeth.
The problem is that this adaptation can perpetuate a swallowing pattern that should already have disappeared.
192 Children, Two Groups, One Striking Difference
The study was conducted from June to August 2024 and involved 192 children aged 4–6 years. Ninety-six children who had lost all four crowns of their upper primary incisors were assigned to one group, while 96 children with intact upper anterior tooth crowns were assigned to the other. Tongue thrusting was assessed using the Weiss and Van Houten method. The children were asked to swallow approximately 10 mL of water while the operator observed tongue movement by gently lowering the child's lower lip and simultaneously assessing masseter muscle activity.
The contrast was striking. In the group with intact teeth, only 21.88% demonstrated tongue thrusting. In the group that had lost their tooth crowns, the figure rose to 80.21%. A chi-square test confirmed that the difference was statistically significant, with p = 0.001.
“Loss of the crowns of the upper anterior primary teeth can interfere with the function of the anterior teeth as a seal during swallowing. This makes it difficult to close the anterior part of the mouth during swallowing, causing the tongue to be positioned between the upper and lower anterior regions and contact the lips, forming a tongue-thrust swallowing pattern.”
This finding is particularly interesting because previous debates regarding this association had largely relied on theoretical studies and expert opinions. Earlier studies, including those cited from Moss and Maccardo, relied on secondary medical-record data rather than direct clinical examinations. The Kulon Progo study helps fill this gap.
Not the Only Cause, but a Factor That Cannot Be Ignored
Two additional findings provide a more complete picture. First, 19.79% of children who had lost their teeth did not exhibit tongue thrusting. The researchers suggested that this could be because the tooth loss had occurred only recently or because the children's orofacial development was sufficiently mature that their swallowing muscles no longer depended on the presence of the anterior teeth.
Second, 21.88% of children with intact teeth still demonstrated tongue thrusting. This reinforces the fact that the condition is multifactorial. Respiratory disorders, chronic tonsillitis, allergies, macroglossia, narrow dental arches, and delayed neuromuscular development can all trigger the same habit. Cerebral palsy and bruxism have also been documented as risk factors.
In other words, loss of the anterior primary teeth is not the only pathway to tongue thrusting, but it is one of the most readily preventable.
A Message for Parents and Dentists
The clinical implications of the study by drg. Putri Kusuma Wardani Mahendra, M.Kes., Sp.KGA., and her team are clear: preserving the crowns of the upper anterior primary teeth is not merely a matter of aesthetics or a child's self-confidence. It is also about maintaining the functional architecture of the oral cavity so that mature swallowing patterns can develop properly.
If tongue thrusting persists, the consequences can be long-lasting, including anterior open bite, proclination of the maxillary incisors, speech disorders, and malocclusion requiring years of orthodontic treatment. Devices such as a fixed tongue crib are available to correct the habit, but preventing the gap from developing in the first place is certainly preferable.
Behind the figures from those six kindergartens in Kulon Progo lies a simple reminder that can sometimes be overlooked: primary teeth that become severely decayed and are allowed to deteriorate do not merely leave a mark on a child's smile. They can also affect the way the tongue moves—potentially for years to come.
Source DOI: http://10.24198/jkg.v37i3.60704
Authors: Nanda Ayu, drg. Achmad Zam Zam Aghasy, M.Kes.
Photo: Pexels