This systematic review was performed to investigate the usefulness and clinical effectiveness of skeletal anchorage devices to determine the most effective bone anchor system for orthodontic tooth movement. Literature on bone anchorage devices was selected from PubMed and the Cochrane Library from January 1966 to June 2010. 55 publications regarding miniplates, miniscrews, palatal implants and dental implants as orthodontic anchorage were identified for further analysis. All bone anchorage devices were found to have relatively high success rates and demonstrated their ability to provide absolute anchorage for orthodontic tooth movement. Significant tooth movement could be achieved with low morbidities and good patient acceptance. The reported success rates for the four groups of anchorage systems were generally high with slight variability (miniplates 91.4–100%; palatal implants 74–93.3%; miniscrews 61–100%; dental implants 100%). It was concluded that bone anchorage systems can achieve effective orthodontic movement with low morbidities. The success rate is generally high with slight variability between miniplates, palatal implants, miniscrews and dental implants. Owing to the lack of randomized controlled trials, there is no strong evidence to confirm which bone anchor system is the most effective for orthodontic tooth movement.
Dental anchorage is defined as the resistance to unwanted tooth movement. Anchorage control is a prerequisite for the success of orthodontic treatment. Loss of dental anchorage during orthodontic treatment leads to uncontrolled occlusal results. Conventionally, extra-oral (headgear, protraction headgear) and intra-oral (transpalatal arch (TPA), quadhelix) appliances are used to reinforce anchorage. The use of extra-oral appliances is hampered by poor patient compliance and potential iatrogenic injuries associated with these appliances. Intra-oral appliances eliminate the need for patient compliance but they depend on the relative number of dental anchorage units and periodontal support. In the majority of cases using intra-oral anchorage appliances, there are certain degrees of anchorage loss resulting in dental shifting or tilting.
Absolute anchorage is defined as no movement of the anchorage unit as a consequence of the reaction forces applied to move teeth. This relatively new treatment concept overcomes the limitation associated with conventional orthodontic anchorage devices. Absolute anchorage can only be achieved if the anchorage devices are fixed in bone. Such devices include miniplates, miniscrews, palatal implants, onplants and dental implants.
Since the introduction of bone anchorage devices by Creekmore in 1983 and Jenner in 1985, there have been a number of reports and clinical studies regarding the use and effectiveness of miniplates, miniscrews and palatal implants.
Since the use of bone anchor devices became more popular and the number of studies regarding different bone anchor systems increased, review articles have been published. Some are narrative reviews and others only report on the survival and failure rates of one type of system. There is no systematic review in the literature so far that evaluates the efficiency and efficacy of orthodontic bone anchors. The choice of bone anchors is primarily based on the clinicians’ preference and expertise.
The objective of this systematic review was to investigate the clinical effectiveness of miniplates, miniscrews, palatal implants, onplants and dental implants as skeletal anchorage devices for orthodontic movement. The authors aimed to determine the most effective current bone anchor system for orthodontic tooth movement in cases of insufficient dental anchorage.
Materials and methods
A MEDLINE search was performed in PubMed and the Cochrane Library from January 1966 to June 2010 as a first round using the following free text words and their combination: ‘mini-screw’, ‘mini-implant’, ‘mini-plate’, miniplate’, ‘palatal implant’, ‘orthodontic anchorage’, ‘skeletal anchorage’ and ‘anchorage’. The computer search revealed 1189 articles and screening of the titles and abstracts was carried out for possible inclusion. The inclusion criteria were: randomized controlled trials (RCTs) and prospective clinical studies regarding the use of bone anchorage devices; publications in English and Chinese; studies with a sample size of at least 10 of each of the treatment modalities. The exclusion criteria were: studies not related to bone anchorage devices; retrospective studies; case reports or case series; and review articles or technical notes.
The second round search involved manual searching of the reference lists of the full-text articles obtained from the first round. Fig. 1 shows the flow chart according to the PRISMA statement describing the search strategy used to locate relevant studies for this systematic review. The reference lists of the 161 selected articles were manually searched and an additional 62 articles were identified. The manuscripts of the retrieved full-text articles were reviewed and the inclusion criteria applied.