Association between maxillary and mandibular apical base lengths and severity of dental crowding or spacing in Class II malocclusion subjects : an in-vitro study

Anterior crowding/ spacing are one of the major problems that inspire patients to undergo orthodontic treatment. Several factors associated with anterior crowding/ spacing includes arch width and length, mesio-distal tooth diameter and proportions. The aim of the present study was to evaluate the relationship of maxillary and mandibular base lengths to the amount of anterior dental crowding/ spacing in patients with complete class II malocclusions. A retrospective study was done with 152 patients who were divided into four groups according to the severity of pre-treatment dental crowding/spacing present in the mandibular arch. Measurements were performed on the pre-treatment dental casts and lateral cephalograms. Statistical analysis was done using t-test and chi-square test. Subjects with complete class II malocclusion and moderate to severe mandibular crowding [?3mm] have significantly smaller base lengths as compared to the subjects with slight crowding or spacing [<3mm]. There exists an inverse correlation between maxillary and mandibular base lengths and the severity of dental crowding and direct correlation with spacing

Heavy metal toxicity in earthworms and its environmental implications: A review

Earthworms are important soil organisms, contributing to many beneficial ecological services that can be harmed by heavy metal contamination. Because of their permeable skin and constant contact with soil through their digestive tract, they are extremely sensitive to soil contamination. Heavy metals get bioaccumulated in their bodies and cause major health problems. In this review, we describe the findings of various studies on the toxicity of heavy metals to earthworms, mechanisms of toxicity, detoxification responses and consequences on the environment. Heavy metals have deleterious impact on earthworms at all levels of organization, including inhibiting enzyme activities, causing DNA damage, reducing survival, growth and cocoon production, altering behavior and reducing total earthworm community diversity and biomass. These negative effects of heavy metals on earthworms can have disproportionate adverse consequences for community stability as well as serious ecological consequences for the entire terrestrial ecosystem. So, heavy metal pollution of soil poses a serious threat to earthworms, reducing their activity and posing a risk to the environment and human health