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Prevalence and Patterns of Multiple Injuries Affecting a Single Permanent Tooth (Combination Injuries): A Systematic
Nitesh Tewari1,2, Alina Wikstrom3,4, Eva Lauridsen5
1Division of Pediatric Dentistry, Division of Orthodontics and Paediatric Dentistry, Department of Dental Medicine, Karolinska Institutet, Huddinge, Sweden.
Background:
Combination injuries or multiple traumatic dental injuries (TDI) affecting a single permanent tooth are clinically significant but remain underrecognized. Although the global prevalence of TDI is well documented, the epidemiology of combination injuries has not been clearly established. This systematic review and meta-analysis aimed to assess the prevalence and patterns of combination injuries in traumatized permanent teeth.
Methods:
A review protocol was registered in PROSPERO (CRD1245967). Comprehensive searches of PubMed, EMBASE, Web of Science, and Scopus were conducted without language or date restrictions on December 4, 2025. Observational studies done in clinical settings involving patients older than 6 years with TDI in permanent teeth and reporting combination injuries were included. Two authors independently performed screening, data extraction, and risk of bias assessment using the Joanna Briggs Institute checklist. Random-effects meta-analyses were performed to estimate pooled prevalence and proportions of specific injury combinations. The certainty of evidence was evaluated using the GRADE framework.
Results:
Thirty studies from 20 countries were included. Among 34,382 traumatized permanent teeth, 7161 presented with combination injuries. Reported prevalence ranged from 2.36% to 48.28%, with a pooled prevalence of 14% (95% CI: 11%-19%; I2 = 98.2%). Denmark demonstrated the highest pooled prevalence among countries represented by multiple studies. The most frequently reported combinations were enamel-dentin fracture with subluxation (25%) and enamel-dentin fracture with concussion (17%). Reporting terminology varied considerably, and many studies did not explicitly document combination injuries. While most studies had a low risk of bias, the overall certainty of evidence was very low.
Conclusions:
The pooled prevalence of combination injuries was 14%, with the highest country-specific prevalence reported in Denmark, and the most common pattern being enamel-dentin fracture combined with subluxation. Considerable variation in reporting terminology and the very low certainty of evidence highlight an urgent need for standardized nomenclature, calibrated diagnostic protocols, and well-designed studies to accurately capture the complexity of these injuries.
