PubMed · 5275504
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M R Joshi, N A Bhatt. 1971. Canine transposition.. https://doi.org/10.1016/0030-4220(71)90033-8
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The cytokines interleukin-1 beta (IL-1 beta) and IL-1 receptor antagonist (IL-1RA) probably play a part in orthodontic tooth movement. Here, the force magnitudes and the area of force application in the compressed periodontal ligament (PDL) were controlled and the velocity of tooth movement correlated with concentrations of IL-1 beta and IL-1RA in the gingival crevicular fluid (GCF). Seven individuals undergoing orthodontic treatment involving maxillary first premolar extractions and distal movement (bodily retraction) of the maxillary canines participated in the 84-day study. For each participant, continuous retraction forces were applied so that they received equivalent PDL stresses of 13 kPa for one canine and 4 kPa for the other. GCF cytokine concentrations from experimental and control teeth were expressed relative to total protein in the GCF and compared using an 'Activity Index' (AI)=Experimental (IL-1 beta/IL-1RA)/Control (IL-1 beta/IL-1RA). The results showed that the velocity of tooth movement in an individual was related to their AI. The correlation between AI and tooth movement was stronger from the distal (R(d)=0.78) than from the mesial (R(m)=0.65) of retracted teeth. The results demonstrate that equivalent force systems produce individual differences in cytokine production, which correlate with interindividual differences in the velocity of canine retraction.
This study compared two different radiographic techniques for localization of impacted maxillary canines: vertical parallax (from a panoramic and a maxillary anterior occlusal radiograph) and magnification (from a single panoramic radiograph). The radiographs and the information regarding the impacted canines were obtained retrospectively from records of patients treated in the Day Stay Unit of the Eastman Dental Hospital. The two different radiographic techniques were tested blind and compared for localization of the impacted canine by six examiners. The 'gold standard' used for the radiographic comparisons was the true position of the canine as recorded at operation. The results showed a wide variation between the six examiners in the prediction of the canine position with the two different techniques. Localization with vertical parallax was more successful overall than with magnification, although the difference failed to reach significance. Seventy-six per cent of the impacted canines could be successfully located with vertical parallax and 66 per cent with magnification. Further analysis showed that, while almost 90 per cent of the palatally impacted canines could be correctly detected with both techniques, less than half of the buccal canines could be detected with parallax and only one in 10 buccal canines could be detected with magnification. If a canine is suspected to be buccally placed from its appearance on a panoramic film and cannot be palpated, further views are justified.
Human primary teeth have been used as indicators of heavy metal exposure for several decades, but the knowledge about the influence of factors such as tooth type and the presence of caries and roots on metal concentrations is limited. Samples of tooth powder from more than 1200 Norwegian primary teeth without fillings have been analyzed for lead, zinc and cadmium content, and 554 of them for mercury. The material represents all groups of tooth types (incisors, canines and molars), carious and non-carious teeth, and teeth with and without roots. Here we investigate how tooth group and the presence of caries and roots are related to metal concentrations in the teeth. We find that carious teeth have higher metal concentrations than non-carious teeth; the difference was statistically significant for lead, mercury and zinc. Teeth with roots have higher lead and zinc concentrations than teeth without roots. We find differences in metal concentrations between the tooth groups for lead, mercury and zinc. Significant, positive correlations are found between lead and the three other metals and between mercury and zinc. We conclude that metal concentrations in primary teeth are affected by the presence of caries and roots and by tooth group.