Abstract
This study examined complications leading to, or possibly leading to, treatment failure, related to the use of the orthodontic bone anchor (OBA). The OBA is a potential means of providing absolute anchorage and consists of a base-plate fixed with mono-cortical screws, a neck piercing the soft tissues, and a coronal part with conventional orthodontic hooks, tubes or slots. The investigation took the form of a single centre prospective registry at a supra-regional teaching hospital. Eighteen patients (average age 21 years) had one to four OBAs placed between January 2000 and February 2002. Altogether 35 OBAs were placed. Follow-up took place until April 2004. Reasons for placing the OBAs were noted together with any associated complications during the follow-up period. Twenty-three OBAs have been removed so far, four prematurely (one of them before it was taken into use, due to a change of treatment plan enforced by loss of the contralateral OBA). Nineteen were removed as planned after completion of the intended tooth movements. Common (but minor) complications included granulations, acute gingivitis and gingival recession. Light mobility of the OBA was also noted in some cases, but without clinical repercussions. The OBA can be loaded directly, at the level of the orthodontic archwire or more occlusally. It can be placed at any site at the circumference of the jaws, given good quality and thickness of the bony wall. Conventional biomechanical techniques can be applied. However, the failure rate (premature loss of OBA) of 8.6% is considered high, and has necessitated changes in the hardware and protocol.
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