Alveolar bone configuration in mandibular first molars with disto-lingual roots: A cross-sectional radiographic study

Background: Precise assessment of anatomical variations and alveolar bone configurations (ABCs) in permanent mandibular first molars (PMFMs) is crucial for effective periodontal treatment. This cross-sectional study aimed to evaluate the prevalence of disto-lingual roots (DLRs) and ABCs in PMFMs and investigate the correlation between DLRs and clinical parameters related to ABCs at the distal aspect of PMFMs. Methods: A total of 572 patients (863 PMFMs) were included in the analysis. The prevalence of DLRs and ABCs (parallel [P], distal inclined [D], and mesial inclined [M] types) and their relationship with clinical parameters were investigated. Multivariable logistic regression analysis was used to identify subject-, tooth-, and site-specific factors influencing the frequency of ABCs at the distal site of PMFMs. Results: The prevalence of DLRs was 28.32% of subjects and 24.22% of examined PMFMs. The presence of DLRs significantly altered the distribution of ABCs, with a notable increase in M type configurations at the distal sites of PMFMs (p < 0.05). Clinical attachment loss (CAL) was significantly greater at the distal sites of PMFMs with DLRs compared with those without (p < 0.05). Multivariable logistic regression revealed that DLRs, lingual furcation involvement, and severe CAL (≥5 mm) were significantly associated with a higher frequency of M type ABCs. Conclusions: Mesial inclined (M) type ABCs were significantly higher in PMFMs with DLRs, lingual furcation involvement, and severe CAL, suggesting a notable link between DLRs and specific ABCs at distal sites of PMFMs. Plain language summary: This study focuses on the unique anatomical structure of disto-lingual roots (DLRs) in permanent mandibular first molars and their impact on periodontal health. The key finding(s) discovered that teeth with DLRs had a significantly higher prevalence of certain patterns of bone loss (mesial inclined configurations) at their distal sites compared with teeth without DLRs. This type of bone loss was associated with more severe clinical attachment loss and lingual furcation involvement. These findings underline the importance of recognizing DLRs as contributing factors in periodontal disease progression and highlight the need for careful diagnosis and tailored treatment strategies.