Prevalence and features of elongated styloid process on imaging studies: a systematic review and meta-analysis

To determine the prevalence of the elongated styloid process (ESP) and its characteristics, such as sex and age of the patient, unilateral and bilateral incidence, besides variations between different populations and panoramic and CBCT examinations.

A search was performed in six databases (PubMed, Web of Science, Scopus, Cochrane, Lilacs, and Embase) to identify observational studies that used imaging exams and assessed ESP prevalence among panoramic radiograph CBCT examinations, whose transversal prevalence studies were included. Furthermore, studies with a specific group of patients or symptomatic patients were excluded. Additionally, Joanna Briggs Institute checklist was used to evaluate the quality of the studies. A meta-analysis was conducted, then subgroup analyses were performed by grouping studies according to the secondary outcomes, with a significance level set at 5%. The Grading of Recommendations Assessment, Development, and Evaluation system was used to rate the certainty in the evidence.

The initial search resulted in 1635 studies, from which 39 articles met the inclusion criteria, encompassing 50,655 participants. The sample size varied between 82 and 5,000 participants. The prevalence of the ESP ranged from 1.3 to 94.8%, with an overall prevalence of 30.2%. The bilateral occurrence was higher than the unilateral one, but no significant predilection was observed according to sex, age, or population. The type of imaging examination also showed no difference in its detection.

The overall prevalence of ESP was 30.2%, with a propensity for bilaterality, but not for any sex, age, or population geographic location. The imaging examination modality did not influence the diagnosis of ESP. However, the quality level of the studies evaluated was very low, demonstrating the need for more homogeneous primary studies on the prevalence of the ESP with a more standardized methodology.

There is no consensus in the literature regarding the prevalence of the ESP and the characteristics of the affected patients that can cause chronic and debilitating discomfort in the head and neck region. Therefore, knowledge about the prevalence and characteristics of this condition would help dental clinicians reach the correct diagnosis.