Timing of Development of the Permanent Mandibular Dentition: New Reference Values from the Fels Longitudinal Study

Estimating chronological age or assessing the rate of maturation in immature individuals is an important task in biological anthropology and clinical practice. One of the most reliable ways of doing this is by evaluating one's dental development, specifically tooth mineralization. However, few chronologies include reference values for very young children, and few provide an extensive documentation of the range of variation surrounding the reported reference values. We present a new chronology of development of permanent mandibular canine and postcanine teeth from birth through age 28 years, based on over 6,000 radiographs of 590 participants of the Fels Longitudinal Study, recorded between 1940 and 1982. Tooth mineralization was scored following the 14-stage system of Moorrees, Fanning, and Hunt (Moorrees et al., 1963a) with an additional crypt stage. We calculated ages of attainment, as well as average age in stage, using transition analysis. We find that variation increases throughout ontogeny for all teeth, though it is generally comparable between girls and boys. The tempo of dental development tends to be faster in girls. Compared to the classic chronology of Moorrees et al. (1963a), partly based on Fels radiographs, in our sample the development of crowns tends to occur at earlier, and development of roots at increasingly later ages. Our results are more similar to chronologies based on more recent, clinical samples (Liversidge, 2009), though the development of tooth roots in our sample occurs at older ages. Anat Rec, 302:1733–1753, 2019. © 2019 American Association for Anatomy     

Cellular profile of the peritumoral inflammatory infiltrate in squamous cells carcinoma of oral mucosa: Correlation with the expression of Ki67 and histologic grading

Background  

Squamous cells carcinoma is the most important malignant tumor with primary site in the oral cavity and, given the great exposure of mucosa and lips to the etiologic factors of this neoplasm, its incidence is high. Investigation of the prognostic determinants is significant for the expectations of treatment proposal and cure of the patient. The local immune response represented by peritumoral inflammatory infiltrate is a possible prognostic factor.     

Abstracts from other journals

The aim of the present study was to clinically evaluate fissure sealants on the occlusal fissures and buccal pits of permanent first and second molars after 20 and 15 years, respectively. The population consisted of 72 children, each of whom had had their four first molars sealed between 1977 and 1980. At the annual examinations, all caries-free, newly erupted second molars were sealed. When sealant was applied to the second molars, the first molars were checked and sealant was reapplied to those that had deficient sealants. At the follow-up, when the subjects were 26–27 years of age, 27 in the original group had moved from the community. Thus, the present result is based on 45 subjects. One hundred and fifty-three sealed first molars and 161 sealed second molars were available for inspection. At the follow-up examination of the first molars 20 years after sealant had been applied, 65% showed complete retention, 22% partial retention without caries, and 1306 caries or restoration in the occlusal fissures or buccal pits. At the 15-year follow-up of the second molars, the corresponding figures were 65%, 30% and 5%, respectively. Of the restored or carious molars, significantly more were found in the mandible than in the maxilla ( P  < 0.001). This longitudinal study showed that pit and fissure sealants, applied during childhood, have a long-lasting, caries-preventive effect.     

Closing anterior open bites by intruding molars with titanium miniplate anchorage

The intent of this study was threefold: (1) to validate true intrusion of molars in adults, (2) to test the stability of miniplates as anchorage for intruding posterior teeth in the maxilla, and (3) to record the skeletal and dental changes of open-bite closure. Four adult patients who had anterior open-bite malocclusions were selected to undergo posterior intrusion with miniplate anchorage to close the open bite; all had true intrusion of the maxillary molars. Mean molar intrusion was 1.99 mm (range, 1.45-3.32 mm). No movement of miniplates occurred at any time during their use or before intentional clinical removal. Open-bite closure was achieved for all 4 patients. Mean closure of incisors was 3.62 mm (range, 3.0-4.5 mm) as the mandibular plane closed 2.62 degrees (range, 1.5 degrees -4.5 degrees ), and the occlusal plane decreased 2.25 degrees (range, 1.0 degrees -3.5 degrees ). Anterior facial heights decreased as the mandible closed and B-point rotated anteriorly and upward.