Tuesday, April 21, 2009

Implant retained over-dentures made more predictable

Implant specialists Sanjay Chopra and Philip Hayter discuss the plus points of these dental appliances.

Implant retained over-dentures on two, three or four implants have been widely used as a treatment modality for fully edentulous mandibles for more than 20 years and there is a substantial literature to support its use and to demonstrate patient satisfaction1.
The relative simplicity of the procedures can make over-denture cases suitable for adequate dentists when embarking on their first few implant cases. The treatment can also be completed in a limited number of appointments, and is often more economical than most other forms of implant treatment, particularly fixed bridges. One other advantage is that, like a conventional denture, over-dentures can restore lip support and facial profile effectively. These factors make it attractive to dentists and patients.

Unfortunately, some implant advertisements and case reports tend to oversimplify the procedure, without addressing the potential risks. A fit, healthy patient with an abundance of bone can certainly be an excellent candidate for one’s first case. However, such patients are hard to come by, particularly in the group of patients seeking over-dentures. It is certainly not the intention of this article to put off anyone who is considering starting out with an implant-retained over-denture.

Conversely, it is more intended to encourage its use, yet pointing out some potential pitfalls.

Medical history

With an ageing population, it is quite common for patients in their seventies and eighties to be seeking implant treatment. There is a high chance that they may have other concomitant conditions, although apparently minor, which may have a significant bearing on the treatment. For example, a significant number of female patients being treated for osteoporosis are prescribed bisphosphonates (e.g. Fosamax) that inhibit osteoclastic activity, and therefore bone healing. There have been reported cases of bisphosphonate-related osteonecrosis of the jaws (BRONJ) that requires serious consideration for all dentists especially where any form of bone surgery is considered, including simple extractions. Although to date, there is limited literature regarding treating these patients, it is considered as a relative contraindication for elective dental implant treatment. Management strategies are available from the American Association of Maxillofacial Surgeons (AAOMS) describing suggested protocols.[2]

Amongst other medical conditions that can affect treatment, are those that may impair bone healing, such as diabetes, Cardiac or respiratory system diseases, steroid treatment, drug, tobacco or alcohol abuse. A detailed medical history is therefore essential before embarking on even uncomplicated cases, and correspondence with treating physicians may be required.

Manual dexterity

Although the aim of an over-denture is to achieve excellent retention, some patients may have difficulty removing the denture. For example, patients with rheumatoid arthritis affecting their hands may struggle. This can be helped by various methods such as adding orthodontic buttons to the buccal surface, using spoons or other tools to remove the denture, but in more severe cases this can still pose a problem.

The patient shown in Figures 1 and 2 shows the case of a 83-year-old woman. She was on bisphoshonates, prescribed by her doctor. She also had severe rheumatoid arthritis for which she had had previous joint replacements. She was also on steroid treatment, but was otherwise quite well and independent. Although her family had tried to talk her out of any form of treatment, she was extremely unhappy with her lower denture and was keen to try implant treatment to help improve her eating ability and her overall quality of life. She was made fully aware of all relevant risks of dental implant treatment and eventually opted to try a lower implant-retained over-denture supported on two implants.

Figure 1: The denture with the blue retentive locator inserts

Figure 2: The patient’s hands, severely affected by rheumatoid arthritis

Figure 3: A very happy patient

Figure 4: The final denture in place

Figure 5: Scan showing cross sectional detail

Figure 6: The four implants as planned, with locator abutments

Figure 7: The overdenture with inserts

Following the management strategies outlined in the position paper by the AAOMS2, we had suggested a three-month bisphosphonate drug holiday with the agreement of the treating physician. Two Astratech Osseospeed implants were placed in the lower canine sites, and a lower over-denture was made after a three-month integration period. The fluoride-modified surface of Osseospeed implants has shown to be highly successful even in compromised bone situations.[3] The ‘locator abutments’ system enabled us to change the retentive inserts as required.Initially, the patient had problems removing the denture even with the lightest blue insert (680gms-retentive holding force). On changing to the red insert for angled implants, the patient managed to remove the denture more comfortably and was delighted with the results.


1. Scientific Review – Documentation on overdentures. www.astratechuk.com
2. American Association of Oral and Maxillofacial Surgeons. Position Paper on Bisphoshonate related osteonecrosis of the jaws. Sept 2006.www.aaoms.org
3. Scientific review – Documentation on Osseospeed.www.astratechuk.com