## 1 Introduction  
In the literature, the survival rates of implants are typically determined in studies undertaken by university researchers [1; 2]. Such studies may have a doubtful base because inclusion and exclusion criteria at universities may be different in comparison to offices of private practitioners. Direct comparative studies between different approaches or even different implant technologies (e.g., Diskimplant(r), blades, one-piece, two-piece, Corticobasal(r) implants) are not available. One of the possible explanations for such a situation is that specialists for alternative treatment strategies are usually not available in one center. The second is that, in most cases, university clinics are tied to one implant manufacturer as the medical equipment supplies are arranged through tenders.  
Another problem is the definition of success criteria in clinical studies [3; 4; 5]. In a number of studies, only those implants that had reached at least the phase of the prosthetic treatment are counted as lost. Other authors include all implants consecutively placed. Data considering the intent-to-treat-principle are, to our knowledge, not available in dental implantology. Hence, the majority of studies are done with a small number of patients and usually only a few dozen or a few hundred dental implants. In the present study, the authors have chosen a different approach to assess the influence of implant design on the outcome of dental implant treatment. Based on the worldwide sales of 254,113 consecutive implants of all types manufactured by Dr. Ihde Dental AG, we have related the number of sold implants to the number of complaints that were made to the quality department of the manufacturer. The manufacturer encourages all customers to return failed or unusable implants by replacing those implants and other parts free of charge. There is no post-sales time limit for this warranty, i.e., such replacements will be done even after many years. As a result, we anticipate that the majority of customers will actually return any faulty implants. Returns of implants are delivered to the manufacturer directly or via a regional or national distributor. However, implants that were removed in a different office than where they were placed are unlikely to be returned to the producer. No limitations are stated in the manufacturer's \"manual for usage\" regarding the implant used in the maxilla or mandible. In this one manufacturer offer are many different implant designs with different surfaces and loading protocols reflecting all the technological development in the field of dental implantology. As a result, we may expect that all implants were placed in the mandible and maxilla and that the dental specialist was able to choose the appropriate implant type for the particular patient. There is only one explicit rule that should be followed in all cases: load (splint) immediate loading systems within 72 h. The manufacturer encourages the treatment provider to use some of the implants (e.g., polished surface) even if severe periodontal conditions occur immediately following extractions and even in severely infected locations under local disinfection coverage [6]. To date, we have not found in the literature a product complaint analysis based on such a large group of implants. The aim of the study was to describe and compare the number of complaints from dental clinics regarding different implant designs and relate it to the sales figures, giving additional insight into the implant market.