Many of us who have had teeth missing may have thought of different options to replace them.
For those of us interested in dental implants as an option, we may wonder what is the most economical number required to replace a span of missing teeth.
One factor that needs consideration would be the physical load that an implant can take and sadly implants do fail if overloaded!
On the other hand it has been demonstrated that we do not need an implant per tooth and each case with careful assessment can have implants placed in strategic positions to allow normal implant loading as well as adequate implant numbers to maintain a good prognosis.
Longer and wider implants can compensate for a decreased number of implants. Longer and wider implants are possible if the bone thickness and height are bountiful.
Obviously 1 missing tooth would need one implant.
What if there were 2 teeth missing next to each other or possibly more?
What if there were no teeth at all in a particular jaw? How many implants do I need now?
There are many factors to be considered before deciding how many implants are needed.
These factors include:
*The length of the span to be restored
*The functional load for that particular area
*The available bone volume and quality of that bone
Implants need about 1.5mm of bone between itself and adjacent teeth but 3mm between implants. Any closer and the bone may recede. Therefore if 2 teeth are missing in the front of the mouth and the span is not too big, It may be better to place 1 implant and cantilever another tooth off this. To cantilever in such a situation, it would be favourable if the available bone width and height allowed for a longer and wider implant.
If there is enough space for 2 implants, obviously the long term prognosis would be more favourable for 2 implants to be used.
In the back of the mouth where there are 2 adjacent teeth missing, the prognosis is better if 2 implants are placed and the crowns joined to each other as bridges to withstand heavy biting forces.
Where there are numerous missing teeth, a few implants strategically placed, would eliminate the need for excessive number of implants.
For example, 3 missing teeth – 1 implant on either side with the dummy tooth in the centre would normally be adequate.
We could even join 2 implants together with a bridge and cantilever a third tooth infront of the implants. Joining 2 implants and cantilevering a tooth backwards offers a greater risk to problems such as porcelain fracture or even implant failure due to greater biting forces in the back of the mouth.
If 4 teeth are missing, 2 implants may work to support 4 teeth especially in the front of the mouth, but further back normally the configuration would be 2 back implants, a dummy tooth and then a third implant in front of the dummy tooth.
In a full arch where there are no teeth, 4 implants strategically placed, could be used to provide a bridge of 10 – 12 teeth. This we call “All on 4″ which is trademarked by Nobel Biocare who have extensively researched this technique.
That would be the minimum implants but if possible, 6 implants are recommended in the lower jaw, and the upper jaw where the bone is softer, 8 implants is more preferable.
The other factor to consider when deciding if 4, 6 or 8 implants are needed, is the available bone height and width as 6 longer, wider implants in the upper jaw may be more than adequate. On the other hand, 8 short narrow implants may be just enough!
A lower jaw may be fully restored with an implant denture supported by 2 implants and similarly the upper jaw would need 4 implants (due to the bone being softer).
Finally, if you grind your teeth and your dentist would tell you if you do, then more rather than less implants are required, coupled with a night guard to be worn nightly to help stop you grinding your teeth.