The vast world of implant systems can seem very diverse to patients investigating their treatment options. In order to give you a little insight into the different systems available, and thus explain their underlying philosophies, we want to first provide some essential facts: The aim of a dental implant is to come as close as possible to the model example set by the natural tooth.
Implants consist of a root part, which is anchored into the bone, securely attached to the crown section, which extends from the root just like natural tooth’s crown, fulfilling the diverse functions of the tooth. Also vitally important are the chewing and speaking functionalities and appearance of the implant.
The beginnings of implantology development took place in Scandinavia (I. Branemark 1960), then spreading to the USA, Germany, Switzerland and then expanding worldwide. The ‘silicon valley’ of implantation development has been right here in our midst for many years now: the region around Lake Constance – Black Forest – Jura is home to the majority of developers and researchers of the implant industry. Well-known manufacturers such as Straumann, Nobel Biocare, IMZ, Camlog, BioHorizons, Frialit, Ankylos, Bauer and SDS Volz have based their research and development locations here. Swiss, German and a few US companies dominate the market. Dental implants may be considered somewhat similar to the watch-making industry due to their intricacies and detailed precision, innovation, and the committed workforce dedicated to both fields. At the same time, developers must have a high level of knowledge and expertise similar to that required when working with medical technologies.
In our region, these branches have known development clusters: Tuttlingen, Basel, Pforzheim, Mannheim, Belfort, Heidelberg.
The materials using in dental implants have not fundamentally changed since they first appeared on the market: titanium came first, and ceramics soon followed. The shape of implants changed from quite bizarre shapes, such as grids, needles, plates, and tubes up the implants that prevail today, generally with screw-shaped roots. The structural upper part for the dental crowns has also varied, from pre-fixed designs, to screw-in designs or cemented conical shapes. All the possible technical solutions imaginable are still constantly being tested in the search for the very best solution.
Here is a brief overview of the main producers working in implantology and the main features of their products:
Straumann 2 product lines, screw-based design, rough titanium surface, screw-in design for affixing the cro
Nobel Biocare 7 product lines, technically similar with rough titanium surfaces and screw-in abutments
IMZ Early implantation system with elastic abutments and extremely rough titanium surfaces
Camlog 3 product lines, all similar in their titanium surface design, but with both push-in and screw-in designs
For both titanium and ceramic implants, new products are constantly being developed and launched to market with a wide range of different features. As is often the case with medical products, the accompanying critical scientific evaluation and rigorous testing cannot keep pace with the constant influx of new product features. As since the basic characteristics of the products have only been tweaked by manufacturers, however, your dentist will be able to rely on a high reliability of the implants.
Ankylos 2 product lines, rough titanium surfaces with deep threads, conical push-in designs and screw-in designs
Bauer Prototype for one-piece implant with a deep-tapping screw thread and rough titanium alloy surface
SDS Volz 4 Experimental product lines, early ceramic implants of the new 4th generation, with screw-in ceramic design
Here are a few more interesting aspects which are considered by your dentist when selecting the right implant system for each individual case:
Different bone qualities require a suitable type of screw thread and a different basic shape for the implant body. As such, in the case of soft bones, “D4” (often the case in the side areas of the upper jaw) a rough, more protruding thread is better for the primary fixing, i.e. the implant fixing into place directly after first screwing in. In this way, very loose bone tissue can initially be fixed; a conical implant will hold more firmly in place in comparison with a parallel-walled one. On the other hand, this dental implant would require a great deal of effort to fit during primary fixing in the case of very hard bone, “D1” (e.g. in the side areas of the lower jaw). In these cases of extremely hard bone, a thread must be cut out into the bone before an attempt can even be made to screw the implant into the bone. All of these aspects are not relevant, however, when it comes to the secondary fixing (the fixing of the implant into the jaw that is achieved after it fuses with the bone), which is the aspect which is actually more important. In this respect, the important features are the microscopic surface structures found on the titanium or ceramic material.
This category also covers implantology considerations regarding which threads are best suited for use in immediate-loading or subsequent-loading treatment approaches. Currently there is a boom in the use of wide-threaded screw types: it is believed that the high-quality primary fixing leads to undisturbed fusing of the bone during the later healing phase. As such, they are better suited to immediate-loading treatment approaches used by dentists.
On the other hand, dentists have to take a significantly greater pressure exerted on the cells that are growing during the sensitive bone growth phase into consideration when using this treatment approach. Many implantologists do indeed try to actively and quickly reduce this pressure exerted by the dental implant after it is screwed into place.
Another interesting aspect that must be considered is how the crown body or ‘attachment’ is anchored onto the implant body. Here we can find the traditional screw-on abutments that give a certain degree of protection against rotation and tilting. Unfortunately, the easy-to-use “external hex” screws have frequently suffered from screws becoming loose, or even fractures occurring.
This is really disastrous in cases where a larger bridge is fixed onto an implant of this type. Due to the loosening of just one screw, the entire reconstruction would generally have to be replaced. This is the reason why all manufacturers have at least one product line with a friction-locking connection formed on the interior part of the implant, in either conical or parallel tube designs. For these solutions, fitting tends to become much more complicated for the dentists: even on inserting the implant, great care must be taken to ensure an identical screwing direction for implant and abutment. This is not easy, as often the structure of the bone itself determines the screwing direction for the implant. As a consequence of this, there was pressure on the developers and manufacturers to develop a more adaptable system.
Using special new surgical and prosthetic protocols (P. Malo, 1990), an extreme angle deviation of more than 30 degrees was required, with corresponding updated drilling techniques. This technology has been made possible through the use of multiple screwed abutments in dental medicine.
Over the course of these developments, it also became clear, for example, that the earlier requirements were not necessary with implants inserted in as parallel a way as possible. The requirement for bridges based on teeth and implants to be able to compensate for mobility turned out to be just as dispensable. The concerns regarding a need to interlock teeth (movable) and implants (immobile) were proven to be unfounded in the 1980s. Rather, just a few important techniques had to be employed during treatments, including special preparation of teeth.
Drilling techniques have also changed radically over the decades: initially it was believed that higher drilling speeds and correspondingly intensified cooling would create the most exact possible hole for implantation. After a few years, dentists started to become more convinced of that fact that holes drilled at lower speeds, with slightly smaller dimensions and therefore using less cooling and still ensuring no damage due to heat production ensured the best healing of implants.
Currently, there is extensive debate on whether it is more beneficial to cement or to screw dentures onto the implant. Both techniques can even be combined, making the debate even more interesting. If crowns are cemented onto implants, there is always the risk that the cement can end up reaching under the surrounding gums and onto the rough implant surface. This then triggers an inflammatory response in the surrounding bone which can put the long-term stability of the implant fixed into the bone at risk. Cementing the crowns does, however, make it easier to fine tune the positioning and height of several implants connected through bridges. Poor positioning leading to incorrect distribution of forces through the implants would also lead to inflammation in the bone and around the implants (‘periimplantitis’). Using cement also ensures that micro-fissures formed between abutments and the screwed-on crowns are sealed tightly against bacteria. This ensures that any accumulation of particularly dangerous anaerobic bacteria (periimplantitis) can be prevented. By screwing on special intermediate pieces milled out using CAD-CAM processes (using bonding adhesives) an attempt is made to combine both advantages whilst overcoming the disadvantages. Special techniques are applied in the dental laboratory in order to achieve this.
It is always amazing to observe how very compelling fundamental treatment principles can be proven to be either superfluous or even turn out to be false over time. A lot has been learned, and is still left to be discovered by both the scientific communities, dentists and industry. The mechanics of living tissue, and its ability to adapt to changing conditions never ceases to astound researchers as they investigate further. At the same time, it is becoming increasingly clear how important the biological regeneration of bone and gum tissue is for the multi-stage healing process of implants in the bone. It is becoming clearer that a variety of medicines, lifestyles, toxins and habits all have an influence on the healing process.