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Mandibular disto-lingual root: a consideration in periodontal therapy.

BACKGROUND
Developmental and morphological abnormalities may contribute to the progression of localized periodontal disease. Although the presence of a disto-lingual root in the mandibular first molar is rare, its role in periodontal destruction has not been examined. The purpose of this study was to evaluate whether the presence of this root contributes to localized periodontal destruction.


METHODS
The presence of the disto-lingual root was identified by examination of two periapical radiographs in each of 197 Taiwanese patients with 332 mandibular first molars. Regression analysis was used to evaluate the relationship between the presence of the root and probing depth, gingival recession, and periodontal attachment loss at the disto-buccal and disto-lingual sites of the molars. The adjusted variables included patient characteristics (age, gender, diagnosis, and general periodontal conditions), tooth (right and left location, tooth mobility, and periodontal category of the molar), and site (bleeding on probing and adjacent furcation involvement).


RESULTS
A disto-lingual root was present in 26.9% of patients and in 21.7% of molars examined. A significant interaction between periodontal category and the presence of disto-lingual root on probing depth and attachment loss at disto-lingual but not disto-buccal sites was observed. Multivariable regression analysis showed a significantly higher probing depth and attachment loss at the disto-lingual site in molars with the disto-lingual root than in molars without the root in teeth classified as having advanced periodontitis.


CONCLUSIONS
Greater probing depth and attachment loss occurred at disto-lingual sites of molars with the roots. The presence of a disto-lingual root may contribute to localized periodontal destruction.