Author:

Keywords:

implant, bone

Abstract:

General Introduction Before predictable and successful dental implants became available, patients who lost more than a few natural teeth often found it impossible to regain full, comfortable masticatory function and facial esthetics. Dental prostheses, especially the removable designs, were far from ideal replacements for natural teeth. The introduction of oral implants, functioning as artificial tooth roots, widened the treatment options to restore a compromised dentition. An evolution in surgical techniques, implant materials, implant designs, surface characteristics, restorative treatment options etc. allow a variety of treatment strategies today. In less than just a few decades, dental implants have moved from the fringes of dentistry to the mainstream. Indeed, implants are now utilized for purposes not foreseen even a decade ago. This fact, combined with the fact that patients become older and that the amount and the quality of bone necessary remain a limiting factor in oral rehabilitation with oral implants is the driving factor behind enhanced research. The overall aim of this thesis was to evaluate different pre-surgical diagnosis tool and surgical techniques in patients with impaired bone quantity or bone quality. Whenever possible a prospective study design was used, in the form of a RCT. Split-mouth designs were used whenever these could enhance the power of the respective studies. These studies resulted in the respective publications in peer-reviewed high quality journals. To obtain the overall aim 2 general hypotheses were pointed out: 1./ Major bone augmentation procedures can, to some extent, be avoided by using different, less invasive treatment options, without interfering with long-term implant outcomes. 2./ Alveolar bone quality can, to some extent, be influenced by using specific treatment modalities but does not seem to interfere with long-term oral implant outcome. To obtain several specific aims 5 specific hypotheses, which are intertwined to some extent, were pointed out. The hypotheses resulted in a number of research questions (RQ.. PART 1: Impaired Bone Quantity 1) Panoramic imaging is not able to overcome fundamental diagnostic limitations in order to achieve sufficient pre-operative information to perform sinus augmentation procedures. RQ1a: To what extent will panoramic imaging overestimate the need for sinus augmentation procedures? RQ1b: Which anatomical features are deformed or masked on panoramic images? Material & Methods: retrospective radiological study 2) Extra short implants and internal sinus augmentation procedures can overcome the limitations of insufficient bone height without major surgical interventions in order to decrease a patient's morbidity and post-operative discomfort. RQ2a: Can extra short implants be used as abutments for the oral rehabilitation in the posterior/anterior area of the maxilla/mandibula in cases of severe bone resorption? RQ2b: Are implant survival rates similar to normal length implants placed in augmented bone? RQ2c: Are less invasive sinus augmentation (internal sinus lifting - 'Summers technique' & Intralift procedures) comparable and equally effective to augment severely resorbed posterior maxillary regions? Do they result in less-postoperative pain for the patient? RQ2d: Do various surgical technique for sinus augmentation have a different impact on the Schneiderian membrane? Does the impact on the Schneiderian membrane have a correlation with the reduction in graft volume during the healing phases? Study 1: Material & Methods: in vivo, RCT with split mouth design in 18 patients requiring bilateral sinus augmentation procedures. Study 2: Material & Methods: in vivo, prospective cohort study 3) The placement of oral implants in patients with very limited vestibule-oral dimensions without pre/peroperative augmentation procedures is a treatment modality showing similar osseointegration rates & marginal bone level alterations as oral implants placed in sufficient amounts of bone. RQ3: Is there a difference in peri-implant marginal bone level alterations between implants placed in very narrow ridges (<4,5mm) compared to wide ridges (>7mm). Material & Methods: in vivo, prospective clinical trial PART 2: Impaired Bone Quality 4) Marginal bone level alterations following treatment with oral implants in the maxilla of post-menopausal women with or without osteoporosis/penia are comparable. RQ 4: Is there a difference in osseointegration rates and peri-implant marginal bone level alterations between healthy and osteoporotic/osteopenic post-menopausal women, as evaluated radiologically? Material & Methods: in vivo, multi-centric, controlled tria 5) The use of L-PRF for ridge preservation is beneficial on bone quantity and quality. RQ5a: Is the use of L-PRF for ridge preservation purposes beneficial in order the diminish the resorption which naturally occurs after extraction? RQ5b: Does the use of L-PRF to fill extraction sockets result in better bone quality? RQ5c: Does the use of L-PRF to fill extraction sockets result in less post-operative pain for the patient. Material & Methods: in vivo, split-mouth RCT 6) Remaining pathologies after extraction have an influence on the occurrence of retrograde peri-implantitis. Material & Methods: narrative review