1. Overdenture Maintenance
NEO Tee Khin BDS, MS, FRACDS, FAMS
Leila had done an excellent job on the technique of overdenture and the video just reinforce the concept. I find this interesting because it is also my favorite way of bring back function to the edentate mandible.

2. Mucosa-Borne Prosthesis
Implant-retained overdenture should follow the basic principles of removable prosthodontics
Good extension for support, retention and stability
An implant-supported overdenture is still a mucosa-borne prosthesis, therefore we still need to follow basic principles of removable prosthodontics. Although we have the help of 2 implants, we still need good extension to achieve maximum support, stability and retention. We need to remember that primary support is provided by the buccal shelf.

3. Bacterial Colonization
P. gingivalis and A. actinomycetemcomitans could be detected around implants supporting a prosthesis in fully edentulous patients for 10 years.
Quirynen M et al. 2005
Implant periodontium have some similarities to natural teeth. The bacteria that colonize natural teeth also tend to colonize implant. And as in periodontitis, the bacterial microflora becomes more anaerobic and more motile rods and spirochaetes, if proper oral hygiene is not maintanied.

4. Need for Oral Hygiene
The same bacteria which were found in residual periodontal pockets also colonized the peri- implant sulcus
Mombelli et al. 1995
Berglundh et al. 1992
Ericsson et al. 1992
Pontoriero et al. 1994
Lindhe et al. 1992
Marinello et al. 1995
Albrektsson und Isidor 1994
Therefore there is a need for oral hygiene maintenance. An implant overdenture had been recognized to have more soft tissue problem, particularly hyperplasia and the more complicated the bar design, the harder it is for the patient to achieve good oral hygiene.

5. Oral Hygiene
The patient need to be instructed on oral hygiene. I find the end-tufted toothbrush particularly useful. I like the ball attachment and locator abutment because they are easier to maintain compared to the splinted bar. The other aspect would be professional cleaning every 6 months at least. I like to use a plastic scaler because a titanium or stainless steel instrument will scratch the implant and result in subsequently more accumulation of plaque and calculus.

6. Oral Hygiene … better to have written post-operative instruction
Blinder et al. 2001
I have not seen a 20 yr-old overdenture patient. With overdenture patients who tend to be elderly, it is better to have written instructions. You can download a sample of this brochure from the Canadian Dental Association website.
In 2001, Blinder and colleagues15 concluded that verbal instructions alone given after oral surgical procedures were insufficient and that written instructions were compulsory to reduce postoperative stress and complaints and to increase patient satisfaction.

7. Recall / Maintenance Visit
Four phases:
Examination, re-evaluation, diagnosis;
Motivation, reinstruction, instrumentation;
Treatment of infected sites;
Polishing, fluoridation, determining recall interval.
Lang NP et al. Biological complications with dental
implants: their prevention, diagnosis and treatment.
Clin Oral Impl Res 2000: 11 (Suppl.):
According to Niklaus Lang, there are 4 phases to the maintenance visit. First is examination and diagnosis, 2nd is reinforcing oral hygiene instruction, 3rd is to treat any infected site and the 4th is to polish and set up the next appointment.

8. Maintenance Needs in a 10-year Study
Courtesy of Dr. NEO Tee Khin, Singapore
The ball group scored best in relation to retention of the overdenture, soft tissue complications, and patient satisfaction at year 10.
Naert I et al. Prosthetic aspects and patient satisfaction with two- implant-retained mandibular overdentures: A 10-year randomized clinical study. Int J Prosthodont 2004;17:401-10
In terms of maintenance, the ball attachment score best in terms of retention, soft tissue problems and patient satisfaction.
36 patient assigned to Ball-retained, bar and clip and magnet
Ball-retained overdentures showed at year 10 the greatest vertical retention force (1,327g), followed by bars (1,067 g) and magnets (219 g).
In the ball group, need for tightening of abutment screws was the most common mechanical complication; in the magnet and bar groups, respectively, the most common complications were wear and corrosion, and the need for clip activation

9. Maintenance Needs in a 10-year Study
In the ball group, need for tightening of abutment screws was the most common mechanical complication.
Naert I et al. Prosthetic aspects and patient satisfaction with two- implant-retained mandibular overdentures: A 10-year randomized clinical study. Int J Prosthodont 2004;17:401-10
The most common problem would be tightening of the ball attachments. That’s easy because it only takes 2 min.
36 patient assigned to Ball-retained, bar and clip and magnet
Ball-retained overdentures showed at year 10 the greatest vertical retention force (1,327g), followed by bars (1,067 g) and magnets (219 g).
In the ball group, need for tightening of abutment screws was the most common mechanical complication; in the magnet and bar groups, respectively, the most common complications were wear and corrosion, and the need for clip activation

10. Simplicity
Courtesy of Dr. NEO Tee Khin, Singapore
Courtesy of Dr. NEO Tee Khin, Singapore
I like ball retained overdenture for its simplicity in design, fabrication and maintenance Having more implants makes the case more complicated, treatment more protracted and cost more with no difference in patient satisfaction

11. Does not allow free rotation More torque and load on implants
Courtesy of Dr. NEO Tee Khin, Singapore
More than 2 implants
Does not allow free rotation
More torque and load on implants
When you have more than 2 implants, you do not allow free rotation. That means the overdenture becomes more implant-supported than mucosa-supported. Therefore there is more torque and load on the implant.

12. Need for Reline
Tallgren A. Resorption of mandibular ridge may compromise stability of denture over time. J Prosthet Dent 1972;27:120-32
Ridges resorb over time, which means that the overdenture being mucosa-borne needs to be relined every few years

13. Implant Placement
Courtesy of Dr. NEO Tee Khin, Singapore
Courtesy of Dr. NEO Tee Khin, Singapore
Poor position and alignment of implant may mean more forces on the implants and more wear on the component, necessitating more maintenance visits
When the implants are too closely spaced, they create more problem because of poorer load distribution and more load and wear on the implant components. In this patient, there is absolutely no need to have 4 implants and 3 attachment. Because the denture was not allowed to rotate when loaded, there is really a lot of wear on the attachment and they needed to be replaced every 3 months. And the fact that this is an esoteric attachment that I am not familiar with just make it worse. This lady had her husband fly from New York to Chicago to pick up new attachments for me to replace them in S’pore. Talk about cost

14. Wear Opposing dentition Bruxism Need for new denture
Courtesy of Dr. NEO Tee Khin, Singapore
Courtesy of Dr. NEO Tee Khin, Singapore
Opposing dentition
Bruxism
Need for new denture
Interestingly, patient don’t brux when there are wearing complete dentures. But as soon as you place implants and they have a solid platform, they start to brux at night if they wear their denture to bed. They have accelerated wear especially if they are opposing a natural dentition. Patients need to be advised that their teeth do wear out and they need to be replaced with additional cost, not free of charge.

15. Maintenance Cost Maintenance event Time (min) Matrix loose 30
Matrix Housing Dislodged
Matrix activation
Matrix replacement
Matrix fracture
Fractured denture teeth/ acrylic 60
Reline denture
New denture
180
Courtesy of Dr. NEO Tee Khin, Singapore
Courtesy of Dr. NEO Tee Khin, Singapore
Watson et al. 2002
Overdenture is often recommended as a cheaper alternative. But look at the list of problems that can occur. It is a well-know fact that that overdenture have more maintenance issue than fixed implant prosthesis. If you consider the time required for maintenance, replacement of components, and remake of dentures, I wonder whether the implant overdenture is a cheaper option. It may in fact be more expensive in the long run.

16. The McGill consensus statement on overdentures
The evidence currently available suggests that restoration of the edentulous mandible with a conventional denture is no longer the most appropriate first choice prosthodontic treatment.
There is now overwhelming evidence that a 2-implant overdenture should become the first-choice treatment for the edentulous mandible.
J Prosthet Dent 2002;88:
The consensus by the experts who met at McGill University was that…