Image 1:  Intraoral welding abutments placed.Image 2 and 3:  Bar bent and welded to abutments — Image 1: Intraoral welding abutments placed.
Image 2 and 3: Bar bent and welded to abutments

Implant retained full arch prostheses have come a long way. Studies have shown that just two implants are capable of retaining a removable denture on the mandible. Some patients would like something more stable that is not removable. A fixed hybrid denture is usually fabricated with some kind of metal bar by a lab. This type of prostheses requires multiple appointments with the dentist to try it in several times to make sure that the fit of the bar and prosthesis matches the mouth. This is an expensive and time consuming process.

In Italy, progress is being made on a procedure that would simplify the metal bar-making process for a fixed denture. They are calling the process intramural welding and seems to be a very promising idea.

This technique was originally published in 2006 by this same author. Intraoral welding is performed once the implants are placed. In this study, four implants are placed intra-foraminally. A special intraoral welding abutment is placed and a metal bar bent to closely approximate all abutments. The bar is then welded to the abutments with a special instrument, that heats, then cools the metal, in a fraction of a second. Once the bar is welded then the abutments and bar are taken out of the mouth, opaqued, and fitted with an acrylic denture. The whole prosthesis can be fabricated and delivered the same day. Because the bar is welded in the mouth with the abutments in place, passive fit is ensured with minimal time and money spent in the process.

In this report, 80 implants were placed and they found a 100% survival rate after 2 years. Only one patient reported and prosthesis problem, which was an incisal fracture that was easily repaired. Survival of implants does not necessarily mean that the implants were successful. The authors looked at bone levels which can give a good indication of success rate, as stable bone levels usually indicate healthy esthetic implants. Average bone levels remained stable through the length of the observation period.

Take home: Intraoral welding can significantly reduce the time, money, and inconvenience of making a bar-implant retained fixed prostheses. This study only looked at mandibular full arch cases, but there is no reason why it could not be applied to upper prostheses as well. It would also be interesting to use these bars with an acrylic restoration for 3-5 unit, acrylic, fixed prostheses that would not include the entire arch. This would be a low cost way to replace many teeth.

Fetner and Hartigan periodontics and implants has been serving the Jacksonville community for over 25 years. The practice is family owned and operated, and is always on the cutting edge of dental technology.

Straumann funds a lot of research for their implants. So it's no surprise that they will have a lot to show for their new titanium-zirconium alloy, known as roxolid in the vernacular. The idea behind this Ti-Zr alloy is that it is stronger, allowing a smaller diameter implant to be created with a chance for fracture. This is great for areas such as the maxillary lateral or mandibular incisor, but can it be used to replace a larger size tooth that just has limited horizontal bone? This randomized controlled study aims to find any differences between a standard 4.1mm titanium implant and the 3.3mm Ti-Zr implant.

Method and Materials: 40 implants were randomized into two groups of 20 for implant placement into anterior or premolar sites. A two stage approach was used (erring on the side of caution, don't want to have a failure for company). Temp placed at 3 months and final restoration at 6 months post implant placement. Patients were followed up for one year.

Results: Surprise, surprise, no statistically significant difference between the groups at all. No difference in bone level, success, bone grafting, etc. Wouldn't expect an implant company to want you to stop buying one of their implants to start buying another one. But realistically, there is no statistically significant difference because they are both good implants and they work.

Some interesting results, though not significant, was the surgery time was shorter in the smaller implants (less drills), and surgeons preferred these implants more than the conventional size. This is surprising because both size implants required the same amount of bone grafting at implant placement. I have a feeling the smaller size has more bone around it when placed even when bone grafting is necessary, thus giving the surgeon some peace of mind.

My thoughts: Many implant companies have a really small implant. If you look at the connection of these implants you will invariably see a really small band of titanium holding the implant together, and that should scare you. This study had only one year of follow up. In a prosthetic complication timeline, one year is nothing. If this Ti-Zr alloy can really prevent prosthetic complications in a small implant than it really is an intriguing product.

Another advantage to smaller implants is: esthetics. As long as they are placed in a way to allow for good esthetic emergence, they allow for greater bone and papilla thickness on either side of the implant, thus allowing fuller and more esthetic papillas.

If this implant can stand the test of time, it may be the best little implant on the market.

Benic G, Galucci G, Mokti M, Hammerle C, Weber HP, and Jung R: Titanium-zirconium narrow diameter versus titanium regular diameter implants for anterior and premolar single crowns: 1-year results of a randomized controlled clinical study. J Clin Periodontol 2013; dii: 10.1111/jcpe.12156