The aim of this study was to review the literature and evaluate the failure rates and factors that affect the stability and success of temporary anchorage devices (TADs) used as orthodontic anchorage. Data were collected from electronic databases: MEDLINE database, Scopus, and Web of Knowledge. Four combinations of term were used as keywords: screw orthodontic failure, screw orthodontic success, implant orthodontic failure, and implant orthodontic success. The following selection criteria were used to select appropriate articles: articles on implants and screws used as orthodontic anchorage, data only from human subjects, studies published in English, studies with more than 50 implants/screws, and both prospective and retrospective clinical studies. The search provided 209 abstracts about TADs used as anchorage. After reading and applying the selection criteria, 26 articles were included in the study. The data obtained were divided into two topics: which factors affected TAD success and to what degree and in how many articles they were quoted. Clinical factors were divided into three main groups: patient-related, implant-related, and management-related factors. Although all articles included in this meta-analysis reported success rates of greater than 80 per cent, the factors determining success rates were inconsistent between the studies analysed and this made conclusions difficult.

The aim of this study was to compare the percentage of reverse-sequencing chewing cycles in 22 children [9 boys and 13 girls; mean age ± SD, 8.6 ± 1.3 and 8.8 ± 1.5 years, respectively), with a unilateral right or left posterior crossbite, before and after therapy. The chewing cycles were recorded using a kinesiograph while the subjects masticated a soft and a hard bolus on both the crossbite and non-crossbite side. Chewing data were acquired before and 6 months after orthodontic treatment of the crossbite with an orthodontic functional appliance, the ‘Function Generating Bite’. The results showed that, before therapy, the percentage of reverse-sequencing chewing cycles on the crossbite side was significantly higher than that on the normal side ( P < 0.001) with both the soft and hard bolus. In addition, the percentage of reverse-sequencing chewing cycles on the crossbite side before therapy was significantly greater than after therapy with both a soft and hard bolus ( P < 0.001). No significant differences were found in the percentage of reverse-sequencing chewing cycles on the non-crossbite side, before or after therapy, either with a soft or hard bolus.