Review articleThe Root and Root Canal Morphology of the Human Mandibular First Premolar: A Literature Review
Section snippets
Materials and Methods
A review of the literature was performed for the mandibular first premolar with respect to the number and type of roots and root canal morphology. Search topics included “number of roots,” “number of canals,” “root canal morphology,” “extra roots,” “anomalies,” and “abnormal morphology.” Studies of the mandibular first premolar identified through PubMed plus hand searching were included, but pooled data from teeth identified only as “premolars” or “mandibular premolars” were avoided. Over 6,700
Number of Roots
Eight anatomical studies that included 4,462 teeth report on data for the number of roots in the mandibular first premolar (11, 14, 16, 20, 21, 29, 47, 71) (Table 1). The majority of the teeth in these studies (97.9%) had a single root. Two roots were found in 1.8% of the teeth studied. Three-rooted (0.2%) and four-rooted (<0.1%) varieties were quite rare.
A study by Trope et al. (15) reported results by number of patients rather than by the total number of teeth. The results of this study are
Discussion
There is a great deal of variation in the literature with respect to the number of roots and internal canal morphology of teeth.
Only a few studies report ethnic or sex differences. A study of full-mouth series of radiographs from 1,000 patients by Amos (74) in 1955 not only reported on bifurcated canal systems of mandibular first premolar teeth, but also inferred a higher incidence in canal bifurcation in African American patients compared to Caucasian patients. The number of patients in each
Conclusions
Major conclusions that can be drawn from this review article are as follows:
- 1
Although most mandibular first premolars have a single root, two-, three-, and even four-rooted forms have been reported as 2.1% incidence when grouped together.
- 2
The majority of mandibular first premolar teeth have a single canal but there is a relatively high incidence, or one-quarter of mandibular premolars, that have two or more canals (24.2%).
- 3
A single apical foramen may be found in mandibular first premolar teeth in
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