Five year clinical outcomes and evaluation of the Oticon 4.5mm 39 2 1. Introduction Innovations in bone anchored hearing implant (BAHI) systems have resulted in more stable implants since their commercial introduction in 1987 [1]. Surgical techniques for paediatric BAHI have also developed from the original techniques involving complete split thickness skin grafts, both with and without a dermatome [2,3] through to modem day techniques now focusing on tissue preservation avoiding the possible complications caused by skin flap necrosis [4,5] and thus reducing skin complication [6-8]. Linear incision techniques have been shown to have a faster healing time and to inflict less pain than dermatome techniques [7,8]. Currently the use of tissue preservation techniques is reported to have the best soft tissue outcomes [6]. In 2009, Oticon Medical introduced a new BAHI system called the Oticon™ wide implant [9]. This system utilises an implant with an increased diameter of 4.5 mm which demonstrated improved outcomes in dental implantation with lower implant failure rates [10,11]. Application of this wider BAHI has been found to have comparable skin reaction rates to the previous 3.75 mm implants and in addition it was noted to be associated with increased survival [12-15]. The wider diameter of these implants increases the surface area contact between the implant and temporal bone providing a greater stability which results in a reduction in spontaneous fixture loss. Recent meta-analysis by Kruyt et al. supports these finding in children demonstrating a 17.1% loss in small-diameter implants compared to a 5.9% for wide-diameter implants [16] although many of the studies included in this utilised a differently designed wide implant. As a result of this evolving evidence some centres advocate early loading of processors in adults as early as 3 weeks [12,17-19] and at 6 weeks in children [20]. Complications associated with the previous generations of narrower BAHI include periabutment soft tissue reactions and fixture (implant) loss through both trauma and failed osseointergration. These have been demonstrated to be higher in paediatric populations [21]. With specific regard to wide (4.5 mm) implants, failure rates of 2.6-4.2% are reported in the adult population [12,15,22,23] and 5.9% in children [16]. Skin reactions require special consideration in the paediatric population. Pubertal hormonal changes result in sebaceous hypertrophy and an associated skin overgrowth which may require longer abutment placement [24]. There is also an acceptance that the lifestyle and behavior of children can result in an anticipated proportion of abutment loss secondary to trauma [25]. This underlies our tertiary paediatric centre’s philosophy of sleeper fixture insertion at the time of the primary procedure. Any fixture loss can be replaced quickly without any delay associated with waiting for osseointegration of a new implant.
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