Volume 3, Issue 1 - Winter 2012

A Comprehensive Review of Mandibular Overdenture Implants: Single Implant Mandibular Overdentures

December 27, 2012

                Implants are fast becoming the standard of care for an edentulous area in the mouth. Whether being used for full mouth restorations or a single tooth replacement, implants are now much more accessible than even five years ago. With that access, comes an increased demand. One of the newer concepts being tested is the use of a single implant to support a mandibular overdenture, a single implant overdenture(SIO). Traditionally, an overdenture has been the use of two or more mandibular implants, but with the increased demand for a better “denture,” a more cost effective treatment with a single implant could instantly change a patient’s lifestyle. A comprehensive review of current literature will help provide an answer to the effectiveness of this treatment plan.

When patients are left edentulated, maintaining a normal diet may not be possible due to the mobility of the mandibular complete denture. [1] When teeth are not present on the alveolar ridge, the ridge will continue to lose height, destabilizing of the complete denture even more. Combined with the perioral musculature and the tongue, keeping the denture in place is near impossible, leading to difficulty eating, sores, and trauma. 1Endosseous implants allow for stable complete dentures that help many patients return to a normal lifestyle. 1  Traditionally, two or more implants were placed for reconstruction. Many considerations are needed prior to deciding the number of implants including health of the patient, attention to oral hygiene, natural anatomy, past dental history, goals, and finances. When all this is taken into mind and a proper treatment plan is formulated, a successful restoration can be made. Currently, two mandibular implants are basically the standard of care for mandibular complete dentures. The two main concerns are: 1) do implants provide a lasting restoration? and 2) do they help patients with their lifestyle? The literature already backs the lifetime of implants with the 2005 study by Dr. Devorah Schwartz-Arad. This found implant survival rates to be 96.1% (11/285 implants did not survive) and a total 10-year cumulative survival rate was 95.4% (maxilla, 83.5%, mandible, 99.5%). The success rate was 70.4% (maxilla, 41.9%; mandible, 80.8%) when using Albrektsson et al.[2]success criteria. The science proves that implants are a long term solution to this problem when loaded with the dentures. Implant supported dentures also have a positive psychological effect as seen in the Emami[3] research paper. In this study, an examination of published efficacy of mandibular implant dentures was reviewed. Though the study stated that more evidence was needed, there was a generalized increase in patient happiness with implant supported overdentures. [4]

As mentioned earlier, the two implant overdenture for the mandible is the most common overdenture. Bilateral mandibular implants provide a cheap and relatively simple solution to the mobility of complete dentures. There is statistical superiority of the implant overdenture to the conventional denture.[5] The soft tissue response showed a slight but significant improvement with implant overdenture therapy.4Most educational institutions offer them at a subsidized cost to provide patients a great restoration and practitioners to learn more about placement and restoration. The theory is to provide retentive elements on both sides of the ridge. The denture would be mainly supported by the tissue but the implants would prevent the denture from displacement. The placement would often be the location of the mandibular canines, but anatomy and the denture itself would drive the implant placement. Also, patients and practitioners should consider if this is the initial treatment plan and more implants would be placed later on.1

Even though this is a perfectly acceptable treatment plan, not all patients can go through with this process. Patients may have defects on the ridges preventing symmetrical placement of the implants or finances can be an issue. Implant costs range from 300-5000USD depending who is placing the implant, where it is being placed, and what type of implant is being used. This does not include any other complications such as bone grafts, sinus lifts, etc. On top of that, a patient would require two implants. Single implant overdentures could be the solution to these problems. As explained earlier, the basic concept with implant overdentures is increased retention of the actual denture. Primary support still would be tissue borne, but displacement from various masticatory forces would be prevented. One in vitro study performed on mandibular models showed that the lateral forces applied to one implant versus two implant supported prosthesis showed similar outcomes, though the attachment to the denture was specific.[6] Studies have shown that the single implant system, in general, is a safe and reliable method of treatment.[7],[8],[9],[10], 11

El-Sheikh et al. 6published in 2010 discussed one stage surgery with early prosthetic loading of a single implant. This study included twenty edentulous patients with problematic mandibular dentures. The implant was placed at the mandibular midline and patients were recalled at 3, 6 and 12 months. Clinical assessments and marginal bone loss using standardized radiographs were recorded. At the end of the recall, the twenty early loaded implants all survived. All implants showed less than 1 mm of marginal bone loss by the end of the 1-year with a significant increase during the follow-up period. Few prosthetic problems were reported. Patient satisfaction was high with a significant increase in all comfort and functional parameters.6

                Cordioli, G., Z. Majzoub, and S. Castagna 7examined what the minimum number of implants required for overdentures are and found that one implant can be an acceptable alternative for conventional dentures. In this study, twenty-one patients, average age of 74.2 years, had one implant placed at the mandibular midline. A five year follow up revealed not a single failed implant. Mean marginal bone loss of the implants was found to be 1.42 ± 0.56 mm with an average pocket depth of 2.41 ± 0.17 mm. The primary issue to be found was a consistently high plaque index, though the tissues themselves had a low gingival index.7

Liddelow, G., and P. Henry in Australia went even further, testing immediate loading of a single implant. 9 This article defined immediate loading as single stage surgery with denture attachment at the same time. Twenty-eight patients at a mean age of 69.8 years had this treatment completed. All implants were placed with primary stability and restored with a ball attachment. Recall was at 3 and 12 months. Of the original twenty-eight, three were unable to be treated immediately due to lack of primary stability. These were treated with a two stage loading protocol. The other twenty-five all survived at the 12 month recall. 9

Finally, a 2010 study placed a single implant into thirty-six edentulous participants. Though the focus of this study was the attachment type from the implant to the denture, a high success rate for the implant itself showed the effectiveness of this treatment.  [11]

In all of these studies, patients found greater satisfactionwith a SIO compared to a conventional complete mandibular denture. But, this only presents half of the concept. The other side is the attachments to the denture. There are a wide variety of types ranging from balls, magnets, and locators. These range in size and diameter. Alsabeeha et al. found that the highest retentive force (36.97+/-2.23 N) was achieved with the 7.9-mm prototype ball attachment design, followed in a decreasing order by the 5.9-mm prototype ball attachment design (32.06+/-2.59 N), the standard 2.25-mm ball attachment (17.32+/-3.68 N), Locator white (12.39+/-0.55 N), Locator pink (9.40 N+/-0.74 N), and Locator blue (3.83+/-0.64 N). [12]Maeda, Y., Horisaka, M. and Yagi, K found that single-implant overdentures with dome-type magnet or ball attachments had biomechanical effects similar to two-implant overdentures in terms of lateral forces to the abutment and denture base movements under molar functional loads in vitro. 8 These two studies found that in general, ball attachments provide the greatest retention with SIOs and that the larger the dimension of the attachment, the greater the retentive forces.

Overall, the studies provide a very positive view on single implant overdentures. This is still a relatively new concept and much more research is required on the subject.  Alsabeeha[13] found that there is a lack of published randomized clinical trials using mandibular single-implant overdentures, opposing maxillary complete dentures. The article also stated that without the evidence from randomized clinical trials, routine use of this novel approach cannot be recommended, compared with using regular diameter implants and matching attachment systems. This should not dishearten dentists, but merely advocate that more research and trials are needed to find if this is a suitable alternative. 12

 

 

Bibliography

  1. Alsabeeha, Nabeel, Alan G. T. Payne, Rohana K. De Silva, and Michael V. Swain. "Mandibular Single-implant Overdentures: A Review with Surgical and Prosthodontic Perspectives of a Novel Approach." Clinical Oral Implants Research 20.4 (2009): 356-65. Print.
  2. Alsabeeha, Nabeel H. M., Alan G. T. Payne, Rohana K. De Silva, and W. Murray Thomson. "Mandibular Single-implant Overdentures: Preliminary Results of a Randomized-control Trial on Early Loading with Different Implant Diameters and Attachment Systems." Clinical Oral Implants Research (2010): No. Print.
  3. Alsabeeha, Nabeel et al. “Attachment systems for mandibular single-implant overdentures: an in vitro retention force investigation on different designs.” The International journal of prosthodontics 23.2 (2009) : 160-166.
  4. Block, Michael S. Color Atlas of Dental Implant Surgery. St. Louis, MO: Saunders/Elsevier, 2007. Print.
  5. Burns, D., J. Unger, R. Elswickjr, and D. Beck. "Prospective Clinical Evaluation of Mandibular Implant Overdentures: Part I—retention, Stability, and Tissue Response†." The Journal of Prosthetic Dentistry 73.4 (1995): 354-63. Print.
  6. Cordioli, G., Z. Majzoub, and S. Castagna. "Mandibular Overdentures Anchored to Single Implants: A Five-year Prospective Study." The Journal of Prosthetic Dentistry 78.2 (1997): 159-65. Print.
  7. El-Sheikh, Ali M., Omar F. Shihabuddin, and Sahar M. F. Ghoraba. "A Prospective Study of Early Loaded Single Implant-Retained Mandibular Overdentures: Preliminary One-Year Results." International Journal of Dentistry 2012 (2012). Print.
  8. Emami, Elham, Guido Heydecke, Pierre H. Rompré, Pierre De Grandmont, and Jocelyne S. Feine. "Impact of Implant Support for Mandibular Dentures on Satisfaction, Oral and General Health-related Quality of Life: A Meta-analysis of Randomized-controlled Trials." Clinical Oral Implants Research (2009). Print.
  9. Liddelow, G., and P. Henry. "A Prospective Study of Immediately Loaded Single Implant-retained Mandibular Overdentures: Preliminary One-year Results." The Journal of Prosthetic Dentistry 97.6 (2007): S126-137. Print.
  10. Maeda, Yoshinobu, Mitsuhiro Horisaka, and Kaztomo Yagi. "Biomechanical Rationale for a Single Implant-retained Mandibular Overdenture: An in Vitro Study." Clinical Oral Implants Research 19.3 (2008): 271-75. Print.
  11. Schwartz-Arad, Devorah. "A Long-Term Study of Implants Supporting Overdentures as a Model for Implant Success." Journal of Periodontology Online. Journal of Periodontology, Sept. 2005. Web. 30 May 2012. .
  12. Vafaee, Fariborz, Masoumeh Khoshhal, Sara Tavakoliza, Zahra Ebrahimzad, Mahdi Kadkhodaza, and Parviz Torkzaban. "Single Implant Retained Mandibular Overdenture with Immediate Loading (Case Report)." Research Journal of Medical Sciences 5.5 (2011): 273-75. Print.

 


[1] Block, Michael S. Color Atlas of Dental Implant Surgery. St. Louis, MO: Saunders/Elsevier, 2007. Print. Pg 3

[2] Albrektsson’s criteria for success:

> Absence of mobility

> Absence of painful symptoms or paresthesis

> Absence of peri-implant radiolucency

> Absence of progressive marginal bone loss

[3] Emami, E., Heydecke, G., Rompré, P. H., De Grandmont, P. and Feine, J. S. (2009), Impact of implant support for mandibular dentures on satisfaction, oral and general health-related quality of life: a meta-analysis of randomized-controlled trials. Clinical Oral Implants Research, 20: 533–544. doi: 10.1111/j.1600-0501.2008.01693.x

[4] Emami, E., Heydecke, G., Rompré, P. H., De Grandmont, P. and Feine, J. S. (2009), Impact of implant support for mandibular dentures on satisfaction, oral and general health-related quality of life: a meta-analysis of randomized-controlled trials. Clinical Oral Implants Research, 20: 533–544. doi: 10.1111/j.1600-0501.2008.01693.x

[5] Burns, D., J. Unger, R. Elswickjr, and D. Beck. "Prospective Clinical Evaluation of Mandibular Implant Overdentures: Part I—retention, Stability, and Tissue Response†." The Journal of Prosthetic Dentistry 73.4 (1995): 354-63. Print.

[6] Maeda, Yoshinobu, Mitsuhiro Horisaka, and Kaztomo Yagi. "Biomechanical Rationale for a Single Implant-retained Mandibular Overdenture: An in Vitro Study." Clinical Oral Implants Research 19.3 (2008): 271-75. Print.

[7] El-Sheikh, Ali M., Omar F. Shihabuddin, and Sahar M. F. Ghoraba. "A Prospective Study of Early Loaded Single Implant-Retained Mandibular Overdentures: Preliminary One-Year Results." International Journal of Dentistry 2012 (2012). Print.

[8] Cordioli, G., Z. Majzoub, and S. Castagna. "Mandibular Overdentures Anchored to Single Implants: A Five-year Prospective Study." The Journal of Prosthetic Dentistry 78.2 (1997): 159-65. Print.

[9] Vafaee, Fariborz, Masoumeh Khoshhal, Sara Tavakoliza, Zahra Ebrahimzad, Mahdi Kadkhodaza, and Parviz Torkzaban. "Single Implant Retained Mandibular Overdenture with Immediate Loading (Case Report)." Research Journal of Medical Sciences 5.5 (2011): 273-75. Print.

[10] Liddelow, G., and P. Henry. "A Prospective Study of Immediately Loaded Single Implant-retained Mandibular Overdentures: Preliminary One-year Results." The Journal of Prosthetic Dentistry 97.6 (2007): S126-137. Print.

[11] Alsabeeha, N. H. M., Payne, A. G. T., De Silva, R. K. and Thomson, W. M. (2011), Mandibular single-implant overdentures: preliminary results of a randomized-control trial on early loading with different implant diameters and attachment systems. Clinical Oral Implants Research, 22: 330–337. doi: 10.1111/j.1600-0501.2010.02004.x

[12] Alsabeeha, Nabeel et al. “Attachment systems for mandibular single-implant overdentures: an in vitro retention force investigation on different designs.” The International journal of prosthodontics 23.2 (2009) : 160-166.

[13] Alsabeeha, Nabeel, Alan G. T. Payne, Rohana K. De Silva, and Michael V. Swain. "Mandibular Single-implant Overdentures: A Review with Surgical and Prosthodontic Perspectives of a Novel Approach." Clinical Oral Implants Research 20.4 (2009): 356-65. Print.