Orthodontic mini-implants

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Orthodontic mini-implants, also known as temporary anchorage devices (TADs) or miniscrews, are small titanium or titanium-alloy screws that are temporarily inserted into the jawbone to provide stable, skeletal anchorage during orthodontic tooth movement. Because they are anchored directly in bone rather than relying on the reaction forces of other teeth, mini-implants allow orthodontists to move teeth more predictably while reducing dependence on patient cooperation with removable appliances such as headgear.^[1][2]

The concept of using bone-anchored devices to resist orthodontic reaction forces, described as "skeletal anchorage," was first proposed by Creekmore and Eklund in 1983, who used a vitallium bone screw placed beneath the anterior nasal spine to intrude incisors.^[3] The term "orthodontic mini-implant" was later introduced by Kanomi in 1997, describing a small titanium screw designed specifically for orthodontic anchorage.^[4] Since then, mini-implants have become a widely used tool in orthodontic practice, expanding the range of tooth movements that can be achieved without relying on patient-compliance-dependent devices or, in some cases, orthognathic surgery.^[1][2]

Mini-implants are typically 1.3–2.0 mm in diameter and 6–12 mm in length, with a screw-shaped body and an exposed head that can be engaged directly by orthodontic wires, springs, or elastics, or connected indirectly via a rigid framework to another anchorage unit. Systematic reviews have found that implants with diameters under 1.3 mm or over 2 mm, and lengths under 8 mm, are associated with higher failure rates.^[5][6] A 2026 survey of Iranian specialist orthodontists found that an 8 mm length was the most frequently preferred option in the posterior mandible, anterior maxilla, and posterior maxilla, while a shorter 6 mm implant was preferred in the anterior mandible, reflecting differences in available bone thickness between sites.^[7]

Mini-implants are most commonly placed in the interradicular alveolar bone of the posterior maxilla and mandible, where the greatest volume of bone is available: in the maxilla, between the second premolar and first molar, and in the mandible, between the second premolar and second molar.^[8][9][7] Additional sites include the zygomatic buttress, palate, and retromolar area, though these are used less frequently than posterior alveolar sites.^[7] Surveys of orthodontists in several countries have consistently found a preference for posterior over anterior placement sites, and for maxillary over mandibular sites.^[7][10]

Most clinicians report loading mini-implants with orthodontic force immediately or shortly after placement rather than waiting for a period of osseointegration, a practice supported by evidence that mini-implants achieve mechanical retention rather than true bone fusion.^[7][11]

Mini-implants are used for a wide range of tooth-movement goals, including:

• Space closure after tooth extraction, allowing more precise control of anchorage than conventional methods^[7][11]
• Distalization of posterior teeth without extractions^[7]
• Intrusion of over-erupted anterior or posterior teeth^[7][12]
• Molar uprighting and protraction^[7][12]
• Midline correction^[7]
• Skeletal expansion of the maxilla and maxillary protraction, though these are comparatively less common indications^[7]

The relative popularity of specific indications varies internationally. In a 2024 survey of orthodontists in Australia and the United Kingdom, molar protraction was the most frequently reported use, followed by anchorage reinforcement and intrusion.^[10] In a survey of orthodontists across five U.S. network states, molar protraction was likewise the leading indication, followed by indirect anchorage for space closure.^[13] By contrast, a 2026 survey of Iranian orthodontists found posterior distalization without extraction to be the most commonly endorsed indication, followed by extraction-space closure and posterior intrusion.^[7]

International surveys indicate that adoption of mini-implants among orthodontists has increased substantially since the early 2000s and now varies considerably by country and year of survey. Reported usage rates include 69.2% among members of the American Association of Orthodontists (AAO) in a 2008 survey,^[14] 91% among orthodontists in five U.S. network states in 2010,^[13] 50% in Switzerland in 2014,^[15] 66% in France in 2015,^[11] 62% in Germany in 2015,^[16] 63% in South Africa in 2016,^[17] 92% in Taiwan,^[18] 77.0% in Australia and 68.6% in the United Kingdom in a 2024 cross-cultural survey,^[10] and 96.6% among specialist orthodontists in Iran in a 2026 survey, the highest usage rate reported to date.^[7]

Reported complications associated with mini-implant placement range from minor and self-limiting to rare but serious. A systematic review identified peri-implant soft-tissue inflammation with mucosal overgrowth, root injury with associated periradicular lesions, loss of pulp vitality, transient loss of pulp sensitivity, tooth discoloration, and soft-tissue necrosis as reported complications, along with rarer perforation of anatomical structures such as the maxillary sinus or nasal cavity floor.^[19] Mini-implant fracture and scarring have also been reported following removal.^[19]

Across surveys, the most frequently reported complications are typically minor: insertion-site pain, soft-tissue irritation or ulceration, and implant loosening or failure requiring replacement. Loss or mobility of the implant was the complication most frequently reported by respondents to international AAO^[20] and UK/Australian surveys.^[10] A 2026 survey of Iranian orthodontists similarly found pain (13.0%), soft-tissue irritation (11.6%), and failure or loosening (9.5%) to be the most commonly reported regular complications, while serious complications such as nerve damage, root injury, sinus perforation, and accidental ingestion or aspiration of the device were rare or unreported.^[7]

Orthodontists report acquiring skills in mini-implant placement through a variety of routes, including postgraduate residency training, manufacturer-run courses and workshops, online training and webinars, and informal learning from colleagues.^[7] Device sourcing also varies by region and reflects both international and domestic manufacturing; for example, a 2026 survey found that Iranian orthodontists most frequently used South Korean-manufactured devices, followed by Chinese, German, and American brands.^[7]