57 3.1 Clinical Evaluation of laser-ablated titanium implant 1. Introduction Since 1977, bone anchored titanium implants have been utilized for the attachment of percutaneous abutments allowing for fixation of sound processors for bone conduction hearing (1). Successful implantation is dependent on osseointegration with the surrounding bone during healing of the implant (2). Osseointegration is in turn influenced by implant geometry (macro, micro, and nanoscale), surface and material properties, drilling protocol, osteotomy configuration, surrounding bone quality, and systemic and local host characteristics (3,4). It has been reported that the pediatric population has either lower or equal implant survival rates compared with adult populations (5) despite fewer patient-related conditions such as high body mass index (BMI), smoking, diabetes, previous local radiotherapy (6). Furthermore, some centers advocate early and immediate loading of processors in adults (7– 11) and at 6 weeks in children (12). These factors underscore the need for accelerated osseointegration, increased stability, and higher survival rates of bone conduction hearing devices in children. One strategy is to increase the diameter and therefore the implant-to-bone contact, which is reported to reduce failure rates in oral implantations (10,13). Compared with the 3.75 mm previous generation implants 4.5 mm diameter wide bone anchored hearing implants (BAHIs) provided similar improvement in survival rates (8,14– 16). In the adult population, a recent systematic review of 1,166 BAHIs of various designs reported an overall survival rate of 97.7% over an average follow-up time of 17 months (17), supporting previous findings of failure rates between 2.6 and 4.2% in the adult population (8,10,16,18). In the pediatric population, wide diameter implants demonstrated a 5.9% implant loss compared with a 17.1% loss with narrow diameter implants (19), irrespective of any other design variation. Previous small-diameter generations of BAHI were also associated with higher peri-abutment soft tissue complications in pediatric populations resulting in requirements of longer abutments (5,20). In dental applications, surface modifications techniques were developed that increased the roughness of the surface of the implant and demonstrated a stronger bone response and better clinical results compared with non-modified implants (3,21). Based on these findings the 4.5 mm wide diameter laser ablated titanium bone anchored implant system, was introduced in 2015. Using laser ablation, a distinct hierarchical structure is created with a combined macro- and microtopography. In addition, a superimposed nanotexture is confined to the valleys of the implant threads. This laser-ablation was designed to promoted stronger bone anchorage during the early healing period of osseointegration than a standard machined implant (22). A recent study evaluating this surface modified implant in adults reported an implant survival of
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