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Predicting Mandibular Third Molar Agenesis from Second Molar Formation
Helen M Liversidge
; Stomatološki i medicinski fakultet Barts, London, Velika Britanija
Sažetak
Objective: to describe the age of mandibular third molar (M3) crypt formation and investigate if root formation of the mandibular second molar (M2) can predict M3 agenesis. Materials and Methods. Mandibular M2 and M3 were categorised into developmental stages of Moorrees et al. (1963). The range and mean age of M3 crypt stage was calculated. Radiographs with M3 at crypt stage (N=150) were selected and the range of M2 formation stage described. The number and probability of M3 developing given M2 stage was calculated using 1749 radiographs. The odds ratio of M3 developing if M2 > R1/2 was calculated using logistic regression. Results. The average age of M3 crypt stage was 8.84 years [range 5.47 to 12.55]. No significant sex or ethnic differences were observed. When M3 was at crypt stage, the range of M2 stages was from crown half up to root three quarters, the most common being from crown complete to root one quarter. By the time M2 was R1/2, 99% of individuals had a visible M3 crypt. Odds ratio of M3 absence at M2 R3/4 or later stage was 0.03 [95% c.i. 0.02, 0.05]. Conclusion. The average age of M3 crypt was during the eighth year and most commonly occured when the adjacent M2 was at crown complete or early root stage. As the root of M2 developed, the likelihood of M3 crypt formation decreased. After M2 stage R1/2, the development of the M3 crypt was unlikely.
Ključne riječi
molar, third; agenesis; odontogenesis
Hrčak ID:
30516
URI
Datum izdavanja:
11.12.2008.
Posjeta: 1.933 *