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Infraoccluded Primary Molars From an Orthodontic Perspective


Infraoccluded primary teeth is a term used to encompass primary teeth which remain stationary without any apparent physical barrier while the adjacent teeth continue to erupt, grow and occlusally develop, all of these lead to vertical alveolar bone defects. Infraoccluded primary teeth were previously referred to as “submerged,”, “retained,” “ankylosed” or“sunken.”


  • Infraoccluded primary teeth mainly affects primary molars (IOPM), hence, the discussion will focus on this type.

  • It affects 14% of children at age 8-9 and 2% above the age of 12 years (Kurol and Thilander, 1984).

  • More common in females than males (Kurol and Thilander, 1984).

  • Mainly affecting primary mandibular second molar (Baccetti, 1998; Shalish et al., 2010; Bjerklin et al., 1992; Antoniades K, 2002).

Classification of IOPM

Based on the vertical level of the occlusal plan of IOPM, it can be classified into (Ekim and Hatibovic‐Kofman, 2001):

  • Mild (Category 1) indicates that the affected molar’s occlusal surface is lying between the level of the adjacent tooth’s occlusal surface and interproximal contact point.

  • Moderate (Category 2) indicates that the affected molar’s occlusal surface is at the level of the adjacent tooth’s interproximal contact point.

  • Severe (Category 3) indicates that the affected molar’s occlusal surface is below the interproximal contact point of the adjacent tooth.

Aetiologies of IOPM

Consequences of IOPM

  • No complication

  • Delayed eruption of successor

  • Overeruption of the opposing teeth

  • Tipping of the adjacent teeth

  • Resorption of proximal root surfaces

  • Ankylosed

Considerations for treatment planning

Treatment of IOPM approach depends on:

  • The presence or absence of primary tooth (Almuzian 2018).

  • Level of infraocclusion and whether the integrity of alveolar bone is compromised or not

  • Early or late stage of diagnosis as early diagnosis has better prognosis

  • Whether space is needed or not to correct inter- and intra-arch problems

Treatment options for IOPM

See the figure below.

Kevin O’Brien in his blog critically appraise a paper which shed the light about the long-term service of Infraoccluded primary molars and canines. I highly recommend reading this blog:

I also co-authored a short review in a local Scottish magazine about this topic which can be accessed from the link below.

A-Z management of Infraoccluded teeth
Download PD • 4.78MB

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