Relationship between Craniovertebral Abnormalities and Maxillary Lateral Incisors Agenesis: A Case-Control Study.

Objectives: This study aimed to investigate whether the sella turcica bridging (STB) and ponticulus posticous (PP) are associated with the congenital missing maxillary lateral incisor (CMMLI), based on lateral cephalograms of patients who needed orthodontic treatment. Materials and Methods: This case-control study examined 160 panoramic images and lateral cephalograms of 2000 patients seeking orthodontic treatment. The case group included 80 patients with CMMLI (40 with unilateral and 40 with bilateral CMMLI) and the control group included 80 patients without CMMLI. Panoramic images were used to diagnose CMMLI and lateral cephalograms showed STB and PP extension. The researchers used statistical analyses to examine the relationship among STB, PP, and CMMLI (P < 0.05). Results: The prevalence of STB type I, II, and III was 47.5%, 35%, and 17.5% in the case group and 72.5%, 22.5%, and 5% in the control group, respectively, determining a positive relationship between CMMLI and STB and a significant relationship between bilateral CMMLI and STB (P < 0.05 for both). The prevalence of normal, incomplete, and complete PP extension was 80%, 5%, and 15% in the case group and 82.5%, 5%, and 12.5% in the control group, respectively. There was no significant relationship between CMMLI and PP extension (P > 0.05) and between the STB and the PP extension (P > 0.05). Conclusion: CMMLI was significantly related to STB but not to PP extension. Investigating the relationship between unilateral/bilateral CMMLI, STB, and PP has shown only a significant relationship between bilateral CMMLI and STB. There was no significant relationship between STB and PP extension.

A comparative study of count models: application to pedestrian-vehicle crashes along Malaysia federal roads.

OBJECTIVES: The objective of this study was to examine the effects of various roadway characteristics on the incidence of pedestrian-vehicle crashes by developing a set of crash prediction models on 543 km of Malaysia federal roads over a 4-year time span between 2007 and 2010. METHODS: Four count models including the Poisson, negative binomial (NB), hurdle Poisson (HP), and hurdle negative binomial (HNB) models were developed and compared to model the number of pedestrian crashes. RESULTS AND CONCLUSIONS: The results indicated the presence of overdispersion in the pedestrian crashes (PCs) and showed that it is due to excess zero rather than variability in the crash data. To handle the issue, the hurdle Poisson model was found to be the best model among the considered models in terms of comparative measures. Moreover, the variables average daily traffic, heavy vehicle traffic, speed limit, land use, and area type were significantly associated with PCs.