Related Experiment Video
Updated: Apr 30, 2026
Systematic Assessment of Mammalian Skull Specimens for Dental and Temporomandibular Joint Pathology
Published on: August 22, 2022
Etiological factors in second mandibular molar impaction
Michele Cassetta1, Federica Altieri2, Sabrina Calasso2
1DDS PhD, Assistant Professor. Department of Oral and Maxillofacial Sciences, School of Dentistry, "Sapienza" University of Rome, Italy.
Objectives:
The impaction of the second mandibular molar (MM2) has recently become more prevalent. Several etiological hypothesis have been proposed to investigate the association between skeletal features and impaction of MM2. The aims of this study were to analyze the skeletal features in patients with MM2 impaction and the association between arrested eruption of MM2 and the presence of the third mandibular molar (MM3).
Study Design:
In this retrospective study 48 subjects from 3,530 Caucasian orthodontic patients with MM2 impaction were included in a study group (SG) and compared to a control group (CG) of 200 subjects without MM2 impaction. Panoramic radiographs evaluated the presence or absence of the MM3 germ. Cephalometric analysis was performed to evaluate linear and angular skeletal values. For the statistical analysis, descriptive statistics, Student's t-test, χ2 test and odds ratio (OR) were used.
Results:
The paired comparisons between SG and CG showed in cephalometric analysis both a reduced mandibular gonial angle (ArGoMe) and lowered Jarabak's polygon value with a statistically significant difference (P≤ 0.05). MM3 was statistically significant associated (P≤ 0.05) with MM2 impaction but it is not a risk factor (OR 0.817).
Conclusions:
Subjects with MM2 impaction show a vertical condylar growth direction. MM3 is not a risk factor for MM2 impaction. Key words:Impacted mandibular second molar, skeletal features, orthodontic.
Related Concept Videos
01:15Teeth
In the bud stage, the tooth germ (an aggregation of cells) starts to form in the developing jawbone. During the cap stage, the tooth germ differentiates into enamel organ, dental papilla, and dental sac, which will later develop into the tooth's enamel, dentin...
01:30Impact
When particles with different initial velocities collide, they induce deformation by applying equal and opposite impulses. At the point of maximum deformation, the particles move together with...
01:21Tooth Anatomy
The Crown, Neck, and Root
The visible part of the tooth is referred to as the crown. It's covered by enamel, the hardest substance in the human body. The crown is uniquely shaped for each type of tooth, allowing for different functions such as cutting, tearing, or...