Page 127 - Craniomaxillofacial Implant Surgery - Jeroen P.J. Dings
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General discussion and future perspectives
surgical templates etc.) and the inconsistency in the reported observations19,22,23. Described deviations in this study can predominantly be explained by the resilience of the skin, since accuracy is mainly dependent on accurate and stable positioning, and inherent support of the surgical template24,25. Resiliency is likely to be negatively influenced by the reduced quality and altered thickness of the soft tissue of fresh frozen cadavers, who were defrosted several times. The initial state of preservation of the material and exact number of freeze-thaw cycles could not be determined. Despite the realistic appearance of fresh frozen cadavers, disadvantages include deterioration of tissue integrity and resiliency26,27. Klop et al. showed increased tissue friability with repeated freeze-thaw cycles28. Furthermore, implant surgery in this study took place at room temperature, while thawing temperature of cadaveric material at lower temperatures is preferred for preservation of physical properties28. Soft tissue thickness was not separately determined. To conclude, the thickness of the soft tissue and subsequent resiliency is likely to have impaired accuracy of the skin-supported surgical templates24,29.
Literature shows that guide support influences the clinical accuracy of computer- guided surgery with tooth-supported surgical templates that offer the highest accuracy2,19,30. Improvement may be found in the installation of osteosynthesis screws prior to the first radiographic scan before virtual planning. Surgical templates can be digitally designed to fit on these osteosynthesis screws to optimize its fit and reduce per-operative rotation and translation of the surgical template and subsequent inaccuracies during implant insertion31.
The results of this study are difficult to compare due to the heterogeneity in literature 7 with regard to study design, methodologies and clinical variations. The linear and
angular deviations are clinically unacceptable and further research and technical improvements are warranted to maintain a safety margin of 2 mm from critical
anatomical structures.
Retrospective multicenter investigation on the optimal timing of implant placement in relation to ablative surgery and survival rate for craniomaxillofacial (CMF) implants (Chapter 4).
In this retrospective study, differences in survival time were evaluated between CMF implants placed during ablation (DA implants) compared to those placed in a later stage, the so-called after ablation (AA) implants. The survival rate for DA-implants with
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