Background Temporary anchorage devices have been used for decades in orthodontic practice for many applications. The aim of this systematic review was to assess the effectiveness of orthodontic temporary anchorage devices in canine retraction during the two-step technique. Methods A search was systematically performed for articles published prior to June 30, 2019 in five electronic databases (PubMed, Embase, Cochrane Central Register of Controlled Trials, Web of Science, Scopus). The risk of bias was assessed using the Cochrane risk of bias tool for randomized controlled trials (RCTs) and the risk of bias in nonrandomized studies of interventions (ROBINS-I) tool for controlled clinical trials (CCTs). The Grading of Recommendation, Assessment, Development and Evaluation (GRADE) approach was used for the quality assessment. Data concerning the mean difference in mesial molar movement and extent of canine retraction were extracted for statistical analysis. The mean differences and 95% confidence intervals were analyzed for continuous data. A meta-analysis with a random-effects model for comparable outcomes was carried out. Results Three RCTs and five CCTs were finally included. Meta-analysis showed a significant increase not only in anchorage preservation in the implant anchorage group in both the maxilla (1.56 mm, 95% CI: 1.14 to 1.98, P < 0.00001) and the mandible (1.62 mm, 95% CI: 1.24 to 2.01, P < 0.00001) but also in canine retraction in the implant anchorage group in both the maxilla (0.43 mm, 95% CI: 0.16 to 0.69, P = 0.001) and the mandible (0.26 mm, 95% CI: 0.02 to 0.49, P = 0.03). Conclusions There is very low-quality evidence showing that implant anchorage is more efficient than conventional anchorage during canine retraction. Additional high-quality studies are needed.

This study investigated the association of the TaqI (rs731236 T>C) polymorphism in the VDR gene with dental caries. Methods: A comprehensive literature search was performed in PubMed, Web of Science, Embase, SinoMed (the Chinese biomedical literature service system), and the Wiley Online Library. Overall comparisons and subgroup analyses based on ethnicity and the presence of dental caries in dentition were performed. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to assess associations between gene polymorphisms and the risk of dental caries. Results: Seven articles were included in this meta-analysis. The pooled results revealed a significant association of the TaqI (rs731236 T>C) polymorphism with dental caries in the allele contrast model (C vs. T: OR = 1.24, 95% CI = 1.07-1.44, I 2 = 42%, p = 0.005) and in the recessive genetic model (CC vs. TT/CT: OR = 1.38, 95% CI = 1.03-1.84, I 2 = 0%, p = 0.03). A stratified analysis based on ethnicity revealed a significant association between the TaqI (rs731236 T>C) polymorphism and the risk of dental caries in Asians (C vs. T: OR = 1.28, 95% CI = 1.06-1.54, I 2 = 60%, p = 0.009). Subgroup analysis based on the presence of dental caries in dentition found a significant association of the TaqI (rs731236 T>C) polymorphism with permanent tooth caries in the allele contrast model (C vs. T: OR = 1.40, 95% CI = 1.11-1.77, I 2 = 76%, p = 0.005) and the recessive genetic model (CC vs. TT/CT: OR = 1.44, 95% CI = 1.03-2.00, I 2 = 0%, p = 0.03). Conclusion:The results of this meta-analysis suggest that the C allele and CC genotype of the TaqI (rs731236 T>C) polymorphism in the VDR gene are associated with an increased risk of dental caries.

Background: To assess the effectiveness of orthodontic temporary anchorage devices in canine retraction during two-step technique. Methods: The search was systematically performed up to June 2019 in five electronic databases (PubMed, Embase, Cochrane Central Register of Controlled Trials, Web of Science, Scopus). A risk of bias assessment was performed using the Cochrane Risk of Bias Tool for Randomized Controlled Trials (RCTs) and the Risk of Bias in Nonrandomized Studies - of Interventions (ROBINS-I) tool for controlled clinical trials (CCTs) . The Grades of Recommendation, Assessment, Development and Evaluation (GRADE) approach was applied for quality assessment. Data concerning the mean difference in mesial molar movement and extent of canine retraction were extracted for statistical analysis. The mean difference and 95% confidence interval were analyzed for continuous data. A meta-analysis with a random-effects model for comparable outcomes was carried out. Results: Three RCTs and five CCTs were finally included. Meta-analysis showed a significant increase not only in anchorage preservation in the implant anchorage group in both the maxilla (1. 56 mm , 95% CI: 1.14 to 1.98, P <0.00001 ) and the mandible (1.62 mm , 95% CI: 1.24 to 2.01, P <0.00001 ) but also in canine retraction in the implant anchorage group in both the maxilla (0.43 mm , 95% CI: 0.16 to 0.69, P =0.001 ) and the mandible (0.26 mm , 95% CI: 0.02 to 0.49, P =0.03 ). Conclusions: Very low-quality evidence shows that implant anchorage is more efficient than conventional anchorage during canine retraction. Further high-quality studies are needed.