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:: Volume 31, Number 1 (winter 2013) ::
J Dent Sch GYEAR__, 31(1): 42-51 Back to browse issues page
Correlation of Mandibular Second Molar Impaction with Third Molar Size, Angulation, Developmental Stage, and Bud Position
Dr. Hassan Ali Shafiee, Dr. Morteza Ghanbarzadeh, Dr. Mohammadreza Nakhostin, Corresponding Author: Dr. Massoud Seifi *
Professor Dept. of Orthodontics , mseifi@sbmu.ac.ir
Abstract:   (2483 Views)

Objective: The present study assessed the association of size, axial angulation, developmental stage and bud position of the mandibular third molar with the second molar impaction in patients with mandibular second molar impaction.

Methods: In this descriptive-analytical study (Case-Control Design), dental records of 5,420 patients in the age range of 12-15 years who underwent orthodontic treatment were assessed out of which 20 patients (14 females and 6 males) with lower second molar impaction were studied. Twenty control patients with erupted second molars were selected from the same centers and matched with the case group. Total sample size was 40 (Case and Control) and had normal distribution for the determined measurements. Third molar axial angulation towards the second molar, first molar and mandibular base, mesiodistal width of 3rd molar / 2nd molar ratio, Nolla developmental stage and third molar bud position were measured and calculated in patients with impacted and erupted second molars and analyzed using student t and chi-square tests.

Results: The mean degree of third molar angulation towards the second molar, first molar and mandibular base was 30.20, 53.6, and 51.3 degrees in cases and 21.4, 34.65 and 45.15 degrees in controls, respectively. Significant differences were found between the two groups in terms of third molar angulation towards the second molar (30.2 Vs 21.4 degrees p<0.047), and first molar (53.6 Vs 34.65 degrees P<0.0001) while no differences were found between the two groups in terms of third molar angulation towards the mandibular base (51.3 Vs 45.15 degrees). The mean mesiodistal width of third molar / second molar ratio was 0.99 in cases and 0.95 in controls with no significant difference. Nolla developmental stage and position of the marginal ridge of the third molar bud towards the second molar showed no definite relation with second molar impaction.

Conclusion: It seems that angulation of third molar to the second and first molars is a major contributing factor to increase the risk of second molar impaction. Third molars size, developmental stages, and bud positions, do not show a significant relation to the second molar impaction.

Keywords: Mandibular second molar, Impaction, Eruption, Third molar
Full-Text [PDF 122 kb]   (939 Downloads)    
Type of Study: Original Article | Subject: Special
Received: 2013/05/18 | Accepted: 2013/08/31 | Published: 2013/08/31
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Shafiee H A, Ghanbarzadeh M, Nakhostin M, Seifi M. Correlation of Mandibular Second Molar Impaction with Third Molar Size, Angulation, Developmental Stage, and Bud Position. J Dent Sch. 2013; 31 (1) :42-51
URL: http://jds.sbmu.ac.ir/article-1-1111-en.html
Volume 31, Number 1 (winter 2013) Back to browse issues page
مجله دانشکده دندانپزشکی دانشگاه علوم پزشکی شهید بهشتی Shahid Beheshti University Dental Journal
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