Single tooth implant is the most common dental implant procedure. Before the advent of dental implants , a single missing tooth in the mouth is replaced with a removable denture or a fixed bridge. The disadvantage of a denture is that it is removable and uncomfortable.
Fixed bridge while being more comfortable, requires the preparation of adjacent teeth
The complexity of single tooth implant depends on the location of the missing tooth. Generally, single tooth implant in the aesthetic zone is technically more challenging and requires more visits and procedures. The location of a missing tooth in various part of the mouth , will have an ultimate bearing on the complexity of the dental implant procedure.
Types of single tooth implant
Single tooth implant – upper jaw back tooth
Single tooth implant – lower jaw back tooth
Single tooth implant – upper jaw front tooth
Single tooth implant – lower jaw front tooth
1. Single tooth implant back tooth
The most important consideration for single tooth implant is t he thickness of the jaw bone and the size of the sinus. The other consideration is the bone density . Upper jaw bone tends to less dense . This is especially so for upper molar areas.
For ideal implant placement , we need a minimum bone height of 10mm. So for patients with bone height of at least 10mm , the dental implant placement procedure is quite straight forward. For patients with bone height of 5- 8 mm , the dental implant placement procedure is a bit more complex as some form of internal sinus lift bone grafting is required
(Internal Sinus Lift)
For patients who have had their upper molars teeth extracted long ago , the jaw bone can shrink to as little as 1 to 4 mm. For such patients, advanced bone grafting such as external sinus lift must be carried out.
(External Sinus Lift)
For patients with low bone density, special adaptive techniques such as osteotome techniques are required . With advancements in implant dentistry, low bone density is no longer a contraindication for implants, although a longer healing period is required
Single tooth implant upper back tooth
Standard case
Ct Scan shows adequate bone height and width for standard dental implant placement. Standard dental implant placement protocol with no bone bone grafting .
Moderately complex
Ct Scan shows bone height of 6 mm with adequate width. A modified dental implant placement protocol with internal sinus lift bone grafting is required.
Complex
Ct Scan shows bone height of 2.2 mm with adequate width. An advance dental implant placement protocol with external sinus lift bone grafting is required. See link external sinus lift
Single tooth implant lower back teeth
The main consideration to the implant dentist is the location of the lower dental nerve that runs through the back of the lower jaw . The minimum height of jaw bone above the lower dental nerve is 8.5 mm. This will allow the implant dentist to install a 8.5mm long implant with a safety clearance of 2mm from the lower dental nerve .
Cone beam CT cross section of lower jaw : standard case
Standard case
The width of the jaw bone is also important.
A good cone beam CT Scan is important as it will show the cross section shape of the jaw. As the biting forces of a molar tooth can be quite high, the implant surgeon will chose an implant of appropriate diameter to suit the anatomy of the patient’s jaw. Ideally, an implant diameter of 4.5 is preferred for good mechanical strength. From the cone beam CT Scan , the implant surgeon can make some preoperative assessment as to whether bone grafting is required during implant placement
Cone beam CT cross section of lower jaw : complex case
7mm length teeth implants
6 mm length tooth implants
Complex case
When a tooth has been lost for a long time or with traumatic extraction, there is considerable loss in vertical bone height. In this case, cone beam CT Scan shows < 8 mm of bone above the inferior dental nerve. Careful and precise implant placement is required so as not to impinge on the lower dental nerve. In order to maintain a safety clearance of 2 mm from the lower dental nerve, a short implant is more appropriate in such cases.
With rapid improvement in implant designs , shorter implants can now be utilized for use in patients with low bone height and close proximity of the lower dental nerve. The new generation of short implants are in the range of 6-8 mm with some as short as 5-6 mm in length
Single tooth implant in the aesthetic zone is the most difficult to do. This is especially so in patients with high lip line showing teeth and gums on smiling.
The picture on the left shows a single tooth implant that has successfully osseointegrated with the jaw bone . However, as far as aesthetics is concerned, it was a total failure. Due to severe bone and gum recession, the final implant tooth looks longer and there is a black hole effect between the 2 central incisors.
1) Careful and gentle extraction of tooth to avoid bone damage. Teeth that requires implants need special extraction techniques so as to preserve bone and gums.
2) Avoid long healing period. Studies have shown that the jaw bone starts to shrink considerably 3 months post extraction . By the first year of tooth loss, the jaw bone can shrink as much as 40 to 60%.
3) Precise implant placement in the jaw bone is of paramount importance. Slight misalignment of implant placement, either too forward, or backward or too deep or too shallow , will have a tremendous effect on the aesthetic outcome.
4) Sometimes bone and gum grafting are required to restore to original shape and contour for good aesthetics.
5) Multi stage dental implant procedure is often required. In most cases, a period of provisional implant crown is required to shape the contour of the gums before the final impression for the definitive implant crown can be done
6) Highly trained dental implant technician. Experience and skill in fabrication of a dental implant crown is also important. This is because fabrication of the implant crown is completely different from those of a conventional crown.
Single tooth implant lower front teeth
3.0 Astra Tech
Osseospeed dental implant
Tooth replacement for a missing lower incisor presents special problems to the implant dentist. Because lower incisors are small, the lack of space is an important pre-operative consideration. Installation of regular size implants will result in damage to adjacent teeth and bone structures .
Recently, with advances in dental implant design and materials, Astra Tech Dental Implant System has produced a 3.0 mm diameter two piece dental implant .
1)Smaller drill hole is required to install the 3.0 Astra Tech dental implant.
2)Less chances of damage to adjacent bone and teeth due to its reduced diameter .
3) More aesthetic for narrow teeth instead of bulky crowns for regular size implant.
4) Superior 2 piece design compared to mini-implants which is one piece.
5) Implant success rate comparable to standard diameter implant when used in the appropriate indications