[ descriptive-clinical study of 134 cases of odontogenic cysts during a 10 year period]

Odontogenic cysts [OC] are relatively common lesions that can behave aggressively and attain large sizes. This study has been conducted to evaluate the prevalence of OCs and their clinical features in three centers in Shiraz which receive most of the oral biopsy specimen in Fars province. In this retrospective study, the histopathologic reports from the archives of the department of pathology of Shiraz Dental School, Khalili and Namazi Hospitals pertaining to a 10 year interval [1375-1385] were reviewed. All odontogenic cysts were listed and their clinical features including sex, age and location were registered and classified according to the latest classification of World Health Organization [WHO] in OCs the results were than descriptively analyzed. Among a total of 110,000 files, 179 were retrieved as OCs after excluding 45 cases of OCs that were non-specifically reported as infected odontogenic cyst. The remainder consisted of 44 cases of radicular syst [32.83%], 42 cases of Dentigerous cyst [31.34%] and 35 cases of Odontogenic keratocyst [26.12%], respectively. OCs was more prevalent in male gender, the posterior mandible and 2nd decade of life. The most frequent OCs, in the studying population were radicular cyst and dentigerous cyst, respectively

[ in vitro evaluation of root anatomy, detection of apical foramen and apical constriction in human mandibular premolar teeth]

Complete knowledge of the morphologic and microscopic anatomy of the dental root apex has been recognized. Internal root canal anatomy especially root apex is variable in human teeth for example lateral canal and ramification may exist. The objective of this study was to determine the internal anatomy of root apex. For this investigation, 50 mandibular first premolar and 50 mandibular second premolar were obtained. The age and sex of the patients and reasons for extraction were not recorded. For better recognition of apical foramen and lateral foramen of the teeth, they were placed in methylen blue for 2 hours and then teeth were studied under the stereomicroscope with x25 magnification lens [the calibration of lens was 0.1mm] and percentage of lateral canal, root deviator and apical foramen exit were detected. Then, to study the internal anatomy, the teeth were grinded and stained with hematoxylin. The mean, standard deviation and standard error for the diameter of constriction and distance from apical foramen were measured. Also, the internal anatomy of the root canal was studied by two observers. The results showed that apical constrictions were always smaller than apical foramen and a distance existed between apical constrictions, apical foramen and vertex. Apical foramen did not exist in center in 80 to 90% of cases. Lateral canals were observed in 28% of mandibular first premolar and in 34% of mandibular second premolar. Also, 90% of first premolar teeth and 88% of second premolar teeth had one canal and 10% of first premolar and 12% of second premolar had two canals. As the mean distance between apical constriction and apical vertex in mandibular first premolars was 0.65mm and in mandibular second premolars was 0.68mm, therefore during root canal treatment and working length determination, this distances should be decreased from tooth length