Root surface measurements of the mandibular first molar

Area of Science:

• Dentistry
• Periodontology
• Dental Anatomy

Background:

• Understanding root surface area (RSA) is crucial for periodontology.
• Mandibular first molars have complex root anatomy, impacting periodontal disease progression.

Purpose of the Study:

• To quantify the root surface area (RSA) per millimeter of root length in mandibular first molars.
• To identify key anatomical landmarks like root trunk length, concavities, and furcation involvement.

Main Methods:

• 20 extracted mandibular first molars were sectioned at 1-mm intervals.
• Photographic projection and calibrated opisometer measurements were used to calculate RSA.
• Root trunk length, concavity location, and intermediate bifurcation ridges (IBRs) were measured.

Main Results:

• Greatest RSA per millimeter was found 4-7 mm apical to the cementoenamel junction (CEJ), in the furcation area.
• 48.7% of total RSA was in the coronal 6 mm of the root.
• Root separation occurred at 4.0 mm apical to CEJ; concavities were present early (0.7 mm buccal, 0.3 mm lingual).
• 70% of teeth had intermediate bifurcation ridges (IBRs); mesial root was larger than distal (1.0:0.88 ratio).

Conclusions:

• The furcation area of mandibular first molars exhibits significant root surface area.
• Early root concavities and the presence of IBRs are common.
• A 6 mm horizontal attachment loss could lead to through-and-through furcation involvement in all studied teeth.