Abstract
Purpose
The timing of loading of titanium craniofacial implants is dependent upon implant characteristics, host factors, and the bonding of titanium oxide and bone referred to as osseointegration. The purpose of this feasibility study seeks to determine the safety of early loading of the Baha BI-300 implant system (Cochlear Limited, Englewood, CO), which has been modified with novel surface texture and geometric design.
Subjects and methods
This prospective study measures implant stability as determined by clinical evaluation and resonance frequency analysis at implantation and at 1, 3, 6, 12, 24 and 52 weeks post-op in 20 patients who underwent single-stage implantation and exteriorization of the BI-300. The processor was loaded at 3 weeks post-operatively. A modified Holger’s classification system was used to evaluate skin reactions.
Results
There was a positive linear trend in mean implant stability scores from implantation to 52 weeks. Only one subject (5%) had a mild local soft tissue Holger’s grade 1 score at 24 weeks. No implant loss or postoperative complications were encountered as a result of the 3-week loading.
Conclusion
Three-week loading of the BI-300 implant did not result in any implant loss or failure of osseointegration. Earlier activation of the external processor with earlier hearing rehabilitation resulted in improved patient satisfaction. Further studies are needed to confirm these results for more universal adoption of early loading in adults.
1
Introduction
The stability and long term survival of titanium implants are believed to be dependent on implant size and surface characteristics, host factors, and the principle of “osseointegration” initially introduced by Professor Brånemark in 1969 . The extra oral use of titanium implants in the temporal bone was pioneered by Tjellström in 1977 , followed by the craniofacial applications.
The original implant loading protocols with the processor empirically called for a waiting period of 3 months in adults and 6 months in children to ensure completion of the osseointegration process and maximal implant stability. Numerous publications have since documented the high rate of implant retention particularly in adult temporal bones .
Based on experiences with the intra oral implants, and animal studies on osseointegration, we first reported our experience in early loading at 6 weeks in 26 adult patients implanted between March 2004 and July 2005 . We have since attached the processor at 6 weeks in all adults with no reported failures.
The purpose of this feasibility study is to confirm the enhanced stability of the newly designed BI-300 ® implant allowing earlier loading at 3 weeks.
2
Materials and methods
The research protocol was approved by the Sarasota Memorial Hospital Institutional Review Board (IRB). The study design was a prospective, within subject, repeated-measures experiment conducted in an outpatient tertiary care center. Twenty adult subjects were implanted with the BI-300 titanium implant between January 2011 and March 2012. The inclusion criteria included: 1) 18 years or older; 2) Subjects had to meet the current FDA audiological criteria for Baha system candidacy; 3) Bone thickness of at least 4 mm at implant site; 4) No pre-existing disease or prior treatment that would compromise bone quality at implant site; 5) Willingness to comply with all requirements of the study protocol. Criteria for exclusion were: 1) Insufficient bone quality or quantity; 2) Unrealistic expectations of the recipient regarding possible benefits, potential risks and limitations of the device; 3) Subject unable to maintain and clean the skin around the abutment; 4) Any medical condition that could affect the healing capacity of the bone or soft tissue.
Preoperative procedures were initiated after informed consent was obtained. Surgery was performed using a one-stage single incision technique with wide subcutaneous tissue thinning down to periosteum. A sleeper implant was placed in all patients as a safety measure in case of loss of the loaded implant. The BI-300 4 mm implant was used in all patients. The implant utilized in this study features a wider diameter of 4.4 mm vs. 3.75 mm in the previous implants, micro-threads at the cylindrical portion of the implant underneath the flange, as well as a roughened implant surface (TiOblast™ microtextured surface by Astra Tech) ( Fig. 1 ).
The primary criteria for evaluation during this study were implant stability, implant loss and local soft tissue reactions. Implant stability was determined using Resonance Frequency Analysis (RFA) at the abutment, using an Osstell® Implant Stability Quotient (ISQ) (Osstell, Göteborg, Sweden) ( Fig. 2 ). This hand-held instrument includes the use of a SmartPeg temporarily attached to the abutment. The SmartPeg is excited by a magnetic pulse from the measurement probe attached to the instrument, and the resonance frequency (the measure of implant stability) is calculated in 1–2 seconds ( Fig. 3 ). This technique is non-invasive and the subjects experience no sensation. Results are displayed as ISQ values with a range from 1 to 100. The higher the number the more stable the implant. RFA analysis has been routinely used in modern implant dentistry as an indicator of implant stability . Two repeated measurements were performed on the subject’s implant in two directions parallel to the skull: anterior–posterior (horizontal) and superior–inferior (vertical).
Local soft tissue reactions at the implant site were evaluated and classified using a modified Holger’s soft tissue reaction grading scale ( Table 1 ). Implant loss was defined as loss of the implant from the site of implantation, including explantation of the implant due to local skin reaction.
| Grade | Clinical description |
|---|---|
| 0 | No irritation: epithelial debris removed if present |
| 1 | Slight redness: temporary local treatment indicated |
| 2 | Red and slightly moist; no granulation tissue present |
| 3 | Red and moist with granulation tissue, skin overgrowth, or scar formation: Local treatment indicated |
| 4 | Extensive granulation, skin overgrowth, or scar formation requiring revision surgery |
| 5 | Removal of skin-penetrating abutment necessary to control infection |
Data collection began at implantation and continued during designated follow-up visits at 1, 3, 6, 12, 24 and 52 weeks post operatively for each subject. ISQ values were obtained at surgery (0 week) and at each interval visit. Local soft tissue reaction was assessed at each follow-up visit beginning at week one. Sound processor loading occurred at week 3. Subjects were assessed for any adverse events at each visit and were recorded as needed. Statistical analyses were performed using SPSS® version 19 and Microsoft® Excel 2007.
2
Materials and methods
The research protocol was approved by the Sarasota Memorial Hospital Institutional Review Board (IRB). The study design was a prospective, within subject, repeated-measures experiment conducted in an outpatient tertiary care center. Twenty adult subjects were implanted with the BI-300 titanium implant between January 2011 and March 2012. The inclusion criteria included: 1) 18 years or older; 2) Subjects had to meet the current FDA audiological criteria for Baha system candidacy; 3) Bone thickness of at least 4 mm at implant site; 4) No pre-existing disease or prior treatment that would compromise bone quality at implant site; 5) Willingness to comply with all requirements of the study protocol. Criteria for exclusion were: 1) Insufficient bone quality or quantity; 2) Unrealistic expectations of the recipient regarding possible benefits, potential risks and limitations of the device; 3) Subject unable to maintain and clean the skin around the abutment; 4) Any medical condition that could affect the healing capacity of the bone or soft tissue.
Preoperative procedures were initiated after informed consent was obtained. Surgery was performed using a one-stage single incision technique with wide subcutaneous tissue thinning down to periosteum. A sleeper implant was placed in all patients as a safety measure in case of loss of the loaded implant. The BI-300 4 mm implant was used in all patients. The implant utilized in this study features a wider diameter of 4.4 mm vs. 3.75 mm in the previous implants, micro-threads at the cylindrical portion of the implant underneath the flange, as well as a roughened implant surface (TiOblast™ microtextured surface by Astra Tech) ( Fig. 1 ).
