The effect of premature extraction of primary molars on spatial conditions and formation of malocclusion – a systematic review

Introduction
Premature loss of deciduous teeth is considered to be one of the local environmental factors interfering with nor-mal development of the occlusion. Extraction of deciduous tooth before the time of its physio­logical exfoliation carries the risk of creation of unfavorable spatial changes in sagittal, transverse and vertical plane. Despite the undeniable role of well-preserved primary dentition in the development of occlusion in adulthood, there are still controversies regarding indications for implementation of space maintainers.

Objectives
Analysis of available literature in terms of consequences of premature loss of deciduous molar teeth.

Material and methods
The literature review was conducted in PubMed, EMBASE and Scopus databases in July 2017 basing on key-word “premature primary tooth loss”. English and Polish-language magazines were taken into account without specifying the time frame.

Results
In total, 20 papers were selected for further detailed analysis, of which 11 were based on longitudinal studies, 9 were cross-sectional studies (including 7 retrospective studies and 2 systematic literature reviews).

Conclusions
Premature extraction of the upper first primary molar may lead to buccal eruption of permanent canine as a con-sequence of more mesial eruption of first premolar. Increased risk of space loss within dental arch exists espe-cially in case of coexistence of cusp to cusp relationship on first molars and leptoprosopic facial type. Conse-quences of losing lower first deciduous molar are less obvious. Extraction of second deciduous molars may result in much more serious disturbances related to mesial migration of first permanent molars, resulting in retention or abnormal eruption of second premolars. Repercussions of early loss of deciduous teeth are often visible only at the moment of eruption of permanent successors and depend on many variables, among which patient’s age at the time of extraction, initial spatial conditions (crowding/spacing) and the number and type of lost teeth should be mentioned.