Longitudinal assessment on the impact of caries status of nearby surfaces on caries progression on the mesial surface of first molars.

BACKGROUND: The mesial surface of the first permanent molar is the most caries-susceptible proximal surface of the permanent dentition in children under the age of 12. AIM: The aim of this study was to determine the association between caries progression on the mesial surface of the first permanent molar (T6M) and caries on the distal surface of the primary second molar (t5D) and the occlusal surface of the first permanent molar (T6O). DESIGN: Children (between 5 and 13 years old; N = 565) that had participated in a 4-year longitudinal caries study that at baseline had at least one T6 fully erupted with a t5 in proximal contact, with no restoration or sealant on T6O and t5D, and adequate bitewing radiographs were included. Clinical data using the International Caries Detection and Assessment System (ICDAS) and radiographs were used to determine the caries status of T6M, T6O, and t5D. RESULTS: Baseline caries presence on t5D and T6O were highly significantly associated with follow-up caries presence on T6M (P < .001). The adjusted odds ratios corresponding to t5D and T6O were 3.94 (95% CI: [1.78, 8.71]) and 3.26 (95% CI: [1.46, 7.31]), respectively. CONCLUSION: These findings highlight the need for prevention and management of caries on T6O and t5D.

Species abundance distributions: moving beyond single prediction theories to integration within an ecological framework.

Species abundance distributions (SADs) follow one of ecology's oldest and most universal laws--every community shows a hollow curve or hyperbolic shape on a histogram with many rare species and just a few common species. Here, we review theoretical, empirical and statistical developments in the study of SADs. Several key points emerge. (i) Literally dozens of models have been proposed to explain the hollow curve. Unfortunately, very few models are ever rejected, primarily because few theories make any predictions beyond the hollow-curve SAD itself. (ii) Interesting work has been performed both empirically and theoretically, which goes beyond the hollow-curve prediction to provide a rich variety of information about how SADs behave. These include the study of SADs along environmental gradients and theories that integrate SADs with other biodiversity patterns. Central to this body of work is an effort to move beyond treating the SAD in isolation and to integrate the SAD into its ecological context to enable making many predictions. (iii) Moving forward will entail understanding how sampling and scale affect SADs and developing statistical tools for describing and comparing SADs. We are optimistic that SADs can provide significant insights into basic and applied ecological science.