Orthopantomograms of a total of 4,063 individuals were included in the study and were taken from patients of the Institute of Dentistry, University of Turku. Impacted teeth were found in 14.1% of the patients. The teeth most frequently impacted were the third molars, 76.1%, and of these, no difference between the maxilla and mandible was observed. No difference in sex in the prevalence of third molars was observed. The prevalence of impacted maxillary cuspids was higher in females than in males. When the prevalence of the third molars in different age-groups was studied, a decrease was found with an increase in age. The prevalence of impacted cuspids was approximately the same in different age-groups.
"Impaction of a permanent tooth is a relatively common clinical occurrence that may involve any tooth in the human dentition. Most commonly it involves the mandibular and maxillary third molars, the maxillary canines or central incisors and the mandibular second premolars  . A tooth is impacted when it fails to erupt due to an obstacle such as the presence of a supernumerary tooth or an odontoma, lack of adequate space in the arch, an abnormal eruption path, or with no apparent etiology (idiopatic) . "
[Show abstract][Hide abstract] ABSTRACT: To determine the prevalence of mandibular second molar impaction in orthodontic patients of two ethnic groups, present treatment options and discuss their outcome. 6500 panoramic radiographs of orthodontically treated patients (3500 Israeli and 3000 of Chinese-American origin) aged 11-15 years were examined for mandibular second molar impactions. 120 patients with 165 impacted mandibular second molars were identified, presenting a prevalence of 1.8%. Many (88%) were mesially angulated. Impactions were more prevalent in the Chinese-American group than in the Israeli group (59% and 41%, respectively). Sequential treatment options are presented and discussed, and the outcomes of several treatments are presented. A prevalence of 1.8% for MM2 impactions was detected in our sample. Clinicians should be aware of the possible impaction of mandibular permanent second molars. Early detection and initiating of orthodontic intervention directed toward correction of the impaction are recommended for best clinical results and long-term prognosis.
"But according to Edamatsu's study, pericoronal radiolucency ≥2.5 mm around the crown of teeth is suggestive pathology. Previous studies have also suggested that pericoronal radiolucency ≥2.5 mm on a panoramic radiograph may state an abnormality. "
[Show abstract][Hide abstract] ABSTRACT: Most common impacted teeth are the mandibular third molars and decision about extraction of them is usually controversial. The presence of pericoronal pathologic changes is an acceptable reason for removal of impacted teeth. Differences in the proliferation rate and apoptosis of odontogenic epithelial cells may influence on the formation of odontogenic epithelial lesions. Therefore, the aim of the present study is to evaluate the immunohistochemical expression of the bcl-2 apoptosis-inhibiting protein and the cell-cycle-related ki-67 antigen in pericoronal follicle of impacted third molars with ≥2.5 mm and <2.5 mm radiolucency.
This was a cross-sectional study that 20 follicles with <2.5 mm radiolucency and 20 follicles with ≥2.5 mm radiolucency were selected by a professional radiologist in digital panoramic radiographs and then referred to a surgeon. Formalin fixed paraffin-embedded tissues were immunohistochemical analyzed for immunoreactivity of bcl-2 protein and ki-67 antigen. The data was analyzed using logistic regression, Spearman correlation coefficient and t-test and Mann-Whitney. P<0.05 was considered significant.
The findings showed correlation between size of the third molar's follicles and expression of bcl-2 protein (P < 0.001, r = 0.556) but there was no correlation between size of third molar's follicles and staining with ki-67 antigen (P = 0.546, r = 0.098). The follicles with radiolucency ≥2.5 mm showed increased immunoreactivity for bcl-2 protein.
The results of study suggest that impacted third molars with radiolucency ≥2.5 mm may be associated with deregulation of cell death, indicated with increased expression of the anti- apoptotic protein bcl-2, while cell proliferation (ki-67) does not seem to play a significant role.
Dental research journal 12/2012; 9(Suppl 1):S26-31. DOI:10.4103/1735-3327.107931
"Dental transmigration or intraosseous migration is an unusual developmental anomaly demonstrating the horizontal movement of an unerupted tooth which only affects the permanent dentition of the lower jaw [4,5]. The mandibular second premolar is the most commonly impacted tooth after the third molars and maxillary canines with an incidence of about 2.1% to 2.7% [6,7]. The frequency of intraosseous transposition of the mandibular second premolar is 0.25% and it more likely affects women (1.7:1 ratio). "
[Show abstract][Hide abstract] ABSTRACT: Intraosseous migration is an unusual developmental dental anomaly, which demonstrates horizontal movement of unerupted teeth only affecting the permanent dentition of the lower jaw. Mandibular second premolar is the most common impacted tooth after the third molars and maxillary canines. Distal migration of the second premolar is rare and early loss of the permanent first molar is one of the most important predisposing factors of intrabony migration of this tooth. Bilateral migration of the mandibular premolars is very rare compared to unilateral migration. Hereby, we present an 18-year-old man with bilateral intrabony migration of the mandibular second premolars to the mandibular angle (at the inferior and buccal side of the mandibular canal) in the presence of first molars. The patient also had nine congenitally missing teeth without any systemic complication or abnormality in the skeleton. The teeth were surgically extracted. The clinical and diagnostic features and treatment of this case are discussed.
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