Study reports high success rate for spontaneous space closure in patients treated with early extraction of first permanent molar

"The success rate of spontaneous space closure was high (84.3%) and was greater in the maxilla (94.1%) than the mandible (74.1%)," the researchers reported.

Age at the time of extraction and the dental developmental stage of the second permanent molar (SPM) were significant factors for successful spontaneous space closure in the maxilla and mandible, respectively.

FPM extraction is often considered a strategic orthodontic intervention, particularly in cases of crowding or malocclusion. Early extraction provides space for the eruption of permanent teeth, facilitating orthodontic treatment and potentially reducing the need for more invasive interventions later in life.

Against the above background, Yasser Aldahool, Folktandvården Stockholm, Spånga, Stockholm, Sweden, and colleagues aimed to assess the success rate of spontaneous space closure after extraction of the first permanent molar in the maxilla and the mandible. They also identified the factors that make spontaneous space closure most favorable.

For this purpose, the researchers searched the database of the Public Dental Service, Stockholm County Council, Stockholm, for young adults born between 2000 and 2001 who underwent extraction of one or more FPM between 2006 and 2016. They identified 995 extracted teeth, of which 203 teeth in 155 patients met the inclusion criteria.

The researchers reported the following findings:

• Of the 203 extracted teeth, 81.8% received no orthodontic treatment.
• The success rate for space closure in orthodontically treated patients was 91.9%.
• The success rate for spontaneous space closure was 84.3%.
• All unsuccessful spontaneous space closures in the maxilla occurred in patients older than 12 years.
• The dental developmental stage of the second permanent molar had a statistically significant association with spontaneous space closure in the mandible.

In conclusion, the following variables were significant for successful spontaneous space closure:

• Maxillary extractions before age 12 were more favorable than extractions done at or after 12.
• Extraction site, with more favorable results for extractions in the maxilla compared to the mandible.
• Dental development of the SPM in stages E and F at the time of the extraction had the most favorable results in the mandible.
• This study could not verify that engagement of the second premolar under the roots of the primary second molar, mesial angulation of the SPM, or the presence of the third molar was significant for successful spontaneous space closure.

"There has been a lack of agreement on the most important factors for spontaneous space closure following the early extraction of FPMs," the researchers wrote.

"Spontaneous space closure after FPM extraction is significantly associated with age and the developmental stage of the SPM in the maxilla and mandible, respectively."