Implant Assisted Overdentures Kevin D. Plummer, DDS Georgia Regents University College of Dental Medicine

Professor, Interim Chair, 
 Department of Oral Rehabilitation Section Director of Removable 
 Prosthodontics Diplomate of the American Board of Prosthodontics

How many in the audience provide complete dentures in your practice?

How many in the audience provide implant supported complete dentures in your practice?

Definition of Overdenture Any removable dental prosthesis that covers and rests on one or more remaining natural teeth, the roots of natural teeth, and/or dental implants; a dental prosthesis that covers or is partially supported by natural teeth , natural tooth roots and or dental implants . The Glossary of Prosthodontic terms 8th edition

Reduction in Face Height of Edentulous and Partially Edentulous Subjects During Long-Term Denture Wearing

• 3 mm face height lost the first year • 5 mm face height lost in 3 years • 7 mm of face height lost in 7 years • Mandibular resorption in 7 years was 4 times that of the maxillary ridge Talgren, A. The continuing reduction of the residual alveolar ridges in complete denture wearers: a mixed-longitudinal study covering 25 years. J Prosthet Dent. 2003 May;89(5):427-35.

Implant Assisted Overdentures

Many patients require acrylic flanges and bulk material to replace missing anatomy – those patients most likely need conventional removable type prostheses These prostheses can be of two basic types and the implants can be placed before or after prostheses fabrication Cagna DR1, Massad JJ, Schiesser FJ. The neutral zone revisited: from historical concepts to modern application. 
 J Prosthet Dent. 2009 Jun;101(6):405-12. doi: 10.1016/S0022-3913(09)60087-1.

Treatment Planning

Treatment Options- Removable Implant retained and 
 tissue supported prostheses

Implant retained and implant 
 supported
 prostheses

Treatment Options- Removable Implant retained and 
 tissue supported prostheses

Implant retained and implant 
 supported
 prostheses

§Stability and retention can be greatly improved with as few as two implants on the mandibular arch. §Many times this increased stability and improved function satisfy the patient.

Implant Retained
 Tissue Supported

De Kok IJ , Chang KH, Lu TS, Cooper LF. Comparison of three-implant-supported fixed dentures and two-implant retained overdentures in the edentulous mandible: a pilot study of treatment efficacy and patient satisfaction. Int J Oral Maxillofac Implants. 2011 Mar-Apr;26(2):415-26. Bakke M1, Holm B, Gotfredsen K. Masticatory function and patient satisfaction with implant-supported mandibular overdentures: a prospective 5-year study. Int J Prosthodont. 2002 Nov-Dec;15(6):575-81.

While the implants stabilize the bone and help prevent further resorption patterns in their vicinity, the tissue supported area must be monitored and maintained Kordatzis K1, Wright PS, Meijer HJ. Posterior mandibular residual ridge resorption in patients with conventional dentures and implant overdentures. Int J Oral Maxillofac Implants. 2003 May-Jun;18(3):447-52.

Implant Retained
 Tissue Supported

Petrie CS, Walker MP, Lu Y, Thiagarajan G. A preliminary three-dimensional finite element analysis of mandibular implant overdentures. Int J Prosthodont. 2014 JanFeb;27(1):70-2. doi: 10.11607/ijp.3425.

Most patients (even long term denture wearers) have enough bone in the mandibular symphyseal region for two implants placed equi-distant from the midline. Information on implant length relatively new.

Implant Retained
 Tissue Supported

Doundoulakis JH1, Eckert SE, Lindquist CC, Jeffcoat MK. The implantsupported overdenture as an alternative to the complete mandibular denture. J Am Dent Assoc. 2003 Nov;134(11):1455-8.

The implants can be joined with a bar substructure and various retentive components

The implants can be used separately with retentive components for each implant

Sadowsky, SJ. Mandibular implant-retained overdentures: A literature review. J Prosthet Dent. 2001 Nov;86(5):468-473.

Implant Retained
 Tissue Supported

Implant Retained
 Implant Supported

Often seen on the maxillary 
 arch using a prosthesis with a framework and no palate

Implant Retained
 Implant Supported

May have a
 substructure

Zou D, Wu Y, Huang W, Wang F, Wang S, Zhang Z, Zhang Z. A 3-year prospective clinical study of telescopic crown, bar, and locator attachments for removable four implant-supported maxillary overdentures. Int J Prosthodont. 2013 Nov-Dec;26(6):566-73. doi: 10.11607/ijp.3485.

Can be supported by single implants and retentive components or bar substructures with various retentive devices.

Implant Retained
 Implant Supported

Arat Bilhan S1, Bilhan H, Bozdag E, Sunbuloglu E, Baykasoglu C, Kutay O. The influence of the attachment type and implant number supporting mandibular overdentures on stress distribution: an in vitro study, part I. Implant Dent. 2013 Feb;22(1):39-48. doi: 10.1097/ID.0b013e31827774ee

SINGLE DENTURES This type of prosthesis is very effective opposing arches with natural teeth or implant assisted removable partial dentures Improved retention and stability make occlusal schemes simpler to fabricate effectively

Implant Retained
 Implant Supported

Sequence of treatment:
 1. Decide number of implants and placement locations
 May require Diagnostic Set-Up or Trial Insertion of Dentures 2. Analyze vertical space available for components A. Bar substructure B. Individual implants

Treatment Planning

Sequence of treatment:
 3. Fabricate Surgical Guides
 4. Determine Occlusal Scheme Balance vs Non-balance 5. Complete fabrication and insertion

Treatment Planning

Sequence of treatment: Decide number of implants and placement locations §Use existing dentures if adequate (may require prosthesis fabrication through trial insertion if no adequate prostheses exist) §Start simple, more implants can be added later §Radiographs, CT imaging, 3D image technology §Articulated diagnostic casts (especially important for vertical space assessment)

Treatment Planning

Sequence of treatment: Analyze vertical space available for components A. Bar substructure

5-7mm 1-3mm

Treatment Planning

6-10 mm

Sequence of treatment: Analyze vertical space available for components B. Individual implants

2.5mm

1.5mm*

*Above tissue level, actual abutment may be taller between fixture and tissue exit

Treatment Planning

Sequence of treatment:

Analyze vertical space available for components Frameworks

Treatment Planning

Sequence of treatment: Fabricate surgical guides (if required)

Treatment Planning

Sequence of treatment: Fabricate surgical guides (if required)

Treatment Planning

Sequence of treatment: Fabricate surgical guides (if required)

Treatment Planning

Occlusion for Complete Dentures Balanced Occlusion Neutrocentric or
 Monoplane Occlusion
 (Non-balanced)

Balanced Occlusion The bilateral, simultaneous contact of posterior teeth in centric relation The bilateral simultaneous contact of posterior and anterior teeth in eccentric positions The anterior teeth do not contact in centric relation

Monoplane Occlusion (Non-balanced) The bilateral, simultaneous posterior 
 occlusal contact of teeth in centric relation. The anterior teeth do not contact in centric 
 relation. No vertical overlap 
 of the anterior 
 teeth

Posterior Tooth Forms

Anatomic Tooth Forms

Semi-anatomic Tooth Forms

Nonanatomic Tooth Forms

Combination Tooth Forms

Bilateral Balanced Denture Occlusion with Anatomic Posterior Denture Teeth Protrusive

Working

Non-Working

Generally uses anatomic or semianatomic teeth Bilateral posterior centric relation contact Anterior & posterior teeth contact in eccentric positions

Centric Relation

Bilateral Balanced Denture Occlusion with Anatomic Posterior Denture Teeth Protrusive

Non-Working

Working

Cross arch and cross tooth balance

Centric Relation

Neutrocentric Occlusion (Non-balanced, Monoplane) Flat mandibular plane Forces directed to ridges Centralized forces Decreased bucco-lingual width of teeth Reduced number of teeth No anterior
 vertical overlap

Centric Relation

Non-Working

Characteristics of Lingualized Occlusion Maxillary - Anatomic or Semianatomic teeth Mandibular arch - Non-anatomic or semi-anatomic teeth Balanced or Neutrocentric occlusion Preferred scheme – Nonbalanced lingualized

Characteristics of Lingualized Occlusion Maxillary - Anatomic or Semianatomic teeth Mandibular arch - Non-anatomic or semi-anatomic teeth Balanced or NeutrocentricNonbalanced occlusion Preferred scheme – Nonbalanced lingualized

Lingualized Occlusion The lingual cusp tips should be in contact with the opposing mandibular teeth. The cuspal inclines of the mandibular teeth are relatively flat, resulting in potentially less lateral forces and displacement during function.

Balanced Lingualized Occlusion

Working Side

Non-working Side Centric Relation

Non-Balanced Lingualized Occlusion

Sequence of treatment:

Fabrication of Prostheses-Bar substructure Bar substructure impressions will need to capture either the fixture or the final abutment in their proper positions in order to fabricate the cast components The final prosthesis impression may be this impression or it may be made after the substructure is finished and placed.

Sequence of treatment:

Fabrication of Prostheses

The interim steps may use the bar or fixtures for stabilization and retention (Record base and occlusion rims for example)

The addition of the retentive components can be during processing (rare) or done intra-orally (most common)

Sequence of treatment:

Fabrication of Prostheses – No substructure Impressions for individual implants usually record the healing cap positions in order to fabricate the prostheses
 to fit around the implant for
 initial insertion and the addition of the retentive
 components intra-orally. This
 is also true for the fabrication
 of framework sub structures
 that use individual implant 
 retention and support.

Goya, A, et.al. A modified impression technique for implant-retained over denture. Indian Journal of Dentistry, (Article in Press), 2014

Frame designed around implants

Frame is processed in denture

Sequence of treatment: Retentive component “Pick Up”

Sequence of treatment:

Retentive component “Pick Up”

1. Personal Preference – Conventional insertion and then pick up of the retentive components after initial adjustment of the prostheses. 2. Many patients don’t want to 
 wait – so! 3. Conventional adjustment of 
 intaglio surfaces and a clinical 
 remount for occlusal adjustment
 and then pick-up

Sequence of treatment: Retentive component “Pick Up” “Block Out Ring”

Add Retentive Component Abutment Selected and Placed

Space cleared for Retentive Components

Final Retentive Component Placement

Measure tissue height Healing abutment removed

Abutments placed

Retentive components placed
 with resin block out protection

Bidra, AS, Agar, JR, et.al. Techniques for incorporation of attachments in implant-retained overdentures with unsplinted abutments. J Prosthet Dent 2012;107:288-299)

Retentive component after “pick up”

Removable Partial Dentures: 
 Implant Overlays

The addition of one or more implants can make an RPD an outstanding restoration. Placement critical in RPD design Provide excellent retention Slow the bone loss typical in the edentulous quadrant

Lifting Force Damaging to Abutment

Fulcrum Point

Removable Partial Dentures: 
 Implant Overlays

Posterior Mandible – Limiting Factors Insufficient height of bone over the Inferior Alveolar Nerve (arrow) to 
 permit placement of a 10 mm or longer implant. Insufficient width of bone. Non-ideal positioning of implant for axial loading due to inadequate bone volume. Single cortical anchorage (arrow).

Removable Partial Dentures: 
 Implant Overlays

Removable Partial Dentures: 
 Implant Overlays

Removable Partial Dentures: Implant Overlays

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Implant Assisted Overdentures

Thank you for your attention!

Lots of things are more important than dentistry Don’t lose that perspective!

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