Is There Sufficient Evidence to Support the "Optimum Time" for Extraction of First Permanent Molars?

Objectives: To evaluate whether the currently available evidence is of an appropriate quality to support the “optimum time” for extraction of first permanent molars (FPMs) to facilitate second permanent molar substitution.
Methods: A comprehensive literature search in five databases was performed using specific keywords. Studies selected were limited to human studies without any language restrictions and the grey literature was screened for additional articles.
PICO based inclusion and exclusion criteria was employed by four examiners and the included articles were blinded for assessment. The examiners independently assessed the articles using the GRADE and STROBE assessment criteria.
Results: Assessment and grading: Only one of the eight studies satisfied 95% of the STROBE criteria and none of them obtained moderate or high GRADE scores. The inter-observer agreement was found to be excellent.
Studies that evaluated the extraction of FPMs based on tooth developmental stage: FPMs extracted in stages D, E, or F, of the Demirjian tooth developmentt stages, exhibited a significantly higher success rate.
Studies that evaluated the extraction of FPMs based on chronologic age: Successful mandibular space closure was evident when FPMs were extracted prior to the age of 12 years.
Studies that evaluated the extraction of FPMs based on arch type: Favourable outcomes (89.9%) namely, complete space closure in the maxillary arch was evident compared to 34% in the mandibular arch.
Conclusions: The currently avaibale evidence is of a poor quality to support the “optimum time” for extraction of first permanent molars (FPMs) to facilitate second permanent molar substitution.Therefore, clinicans should be cautious when implementing the "optimum time" and should consider patient and/or tooth related factors to tailor the treament options to suit the specific needs of the patient.