Over Engineering for Success
Let us imagine for a moment that you are a civil planner and you were building a long bridge. You are presented with 2 different plans from 2 different companies. One bridge costs 75 million dollars and the other 100 million dollars. Upon closer inspection you find that the less expensive bridge is being built on 6 pillars while the more costly one has quoted for 8 pillars. You call in the civil engineers so that you can find out which to choose. After all you don’t want to waste money over engineering this bridge. Money is tight. Both engineers tell you that 6 pillars is the minimum number required to hold this bridge, but the one who planned for 8 tells you that by building to the minimum you have no margin for error. What if the metal fatigues over time? What if the bridge ends up supporting more traffic in the future than you are planning for? What if? He tells you that with 6 pillars you could end up overloading it and risk collapse some day. But with 8 you will stress the bridge less every day and it should last longer. Additionally with 8 pillars you have a little more room to overcome stresses that may occur in the future that are unforeseen today. If you build to the minimum then you risk the 75 million dollars. Additionally, if anything happens it will cost more to fix it in the future than it would to build it right in the first place.
Which bridge do you want to drive on when it is 20 years old? The one built to minimum standards or the one overbuilt?
When we treatment plan a person for implants we have to look at many of the same factors as our civil planners and engineers. First and foremost we need to survey the area where the implants will be placed. How strong is the bone? How much chewing force will be applied? Man or woman? Young or old? Frail or built like a bull? Will the implant teeth be biting against natural teeth, dentures or more implants? What type of teeth will be placed on these implants? The more fixed the teeth are, the more support they require. Removable dentures can be held in place by fewer implants than fixed porcelain teeth. A minimum of 8 implants is required on the upper jaw to support fixed non-removable porcelain teeth, provided that the bone density is good. If the bone density is poor then 10-12 implants may be required. This will vary from person to person depending on the factors listed above. It is always best when engineering anything to over engineer it. If you build to the lowest, cheapest standard then it may work for a while but eventually it will fail. Also when you consider that we hope that the implants will last a lifetime, we have to build in a little bit of a cushion. So let’s say we could support all the teeth on 6 implants at the barest minimum and we place 6. Then we make the porcelain teeth (which by the way cost between $7,000- $14,000 just for the laboratory to make them- not including the dentist’s fees, which are more) and we then lose an implant. Now we are supporting the teeth on just 5 implants which is below the minimum. Soon the other implants will become overloaded and begin to fail. Eventually all the work will be lost. If an engineering cushion had been built in from the beginning by placing 8 or more implants then if one is lost it is no problem. When you consider that everybody heals differently and that on average implants have a survival rate of 96%-97% then it stands to reason that 3-4 out of a hundred will fail to initially integrate. (This usually happens before the porcelain teeth are made but not always) A cushion is therefore not only good engineering from a stress point of view but also from a practical point of view. If I need 8 implants, place 10 and one fails to heal, then we can still continue on and make the teeth. If I place 8 and one fails then we have to wait 3-4 months for the site to heal before we can replace the implant. This will then have to heal for a while again before the teeth are made. Do you really want to wait an extra 6-9 months for your teeth because we didn’t place enough implants?
My philosophy is to over-engineer everything. I want my work to last.