implant retained removable prosthesis: a step-by-step guide from planning to execution

lecture given 9/29/2026, * are things I noticed her take notes on during the presentation

denture need stats

edentulism has declines by 10% in the past decade

90% of edenulous ppl have dentures

33.6 million adults in 1991 to 37.9 million in 2020

79% increase older than 55 yrs in 2020

a sizable minority of the pt population will continue to need complete denture services

what is the ratio of bone resorption in maxilla : mandible?

1:4

how do the maxilla and mandible resorb?

maxilla is up and in

mandible is down and out

what are the treatment goals for an edentulous pt?

retention, stability, support, comfort, esthetics, functions, occlusion

increase in quality of life

what are the treatment options of an edentulous pt?

conventional complete denture

implant retained removable overdenture

implant supported fixed complete denture

*what happens with complete dentures and the lack of PDL?

loss of alveolar bone, no proprioception from PDL

*what happens with implant supported/retained dentures and the lack of PDL?

preservation of alveolar bone

no proprioception from PDL

how should you decide between a fixed or removable implant supported prosthesis?

esthetic factors- need for lip support

restorative space

radiographic data

patient preference and and finance

maintenance

retention

resistance to dislodging dorcess in a vertical direction (away from tissues)

adhesion and cohesion of saliva

atmospheric pressure (peripheral seal)

surface tension

viscosity of saliva

intimate tissue contact

stability

resistance to horizontal and rotational forces (lateral and functional forces)

proper extension of the denture base

accurate border molding and muscle balance

broad and uniform tissue contact

correct denture base form and thickness

balanced occlusion

support

resistance to functional (masticatory) forces directed toward the tissues

maximum tissue coverage

broad, well adapted denture base

proper load distribution over the largest possible surface area

resilient and healthy supporting tissues

when is a maxillaryoverdenture indicated in place of a complete denture?

quality of life is not significantly improved, so only when…

anatomical morphological limitations preclude adequate stability and retention for a CD

patient intolerance for palatal coverage

refractory gagger

when is a mandibular overdenture indicated in place of a complete denture?

always- quality of life is significantly improved by 2 implant supported prosthesis

mcgill consensus statement on overdentures

2 implant overdenture should become the first choice of removable treatment modality for the edentulous mandible

overdenture

a removable partial or complete prosthesis that covers and rests on natural teeth, roots, and/or implants for partial support

implant retained- attachments

tooth retained- abutments with coping, abutments with attachments, non-coping abutments

successful outcomes of implant retained overdentures depends on…

restorative space- adequate vertical and horizontal space for the prosthesis, attachment system, metal framework, and acrylic/tooth thickness

soft tissue conditioners- mucosal quality and thickness, keratinized tissue around implants, vestibular depth and tissue mobility

implant factors- number of implants, implant position and distribution, implant angulation, relationship to the planned prosthesis

residual ridge and bone- bone quantity and quality, ridge anatomy and resorption pattern

how much restorative space is needed for a bar w/ hader clip?

8mm teeth

3mm clip

1mm soft tissue to bar

at least 12mm

how much restorative space is needed for a bar w/ o ring?

8mm teeth

5mm ring

3mm bone crest to soft tissue

at least 16mm

how much restorative space is needed for class I overdentures?

15mm mandibular

15.5mm maxillary posteriorly and 17mm anteriorly

how much restorative space is needed for class II overdentures?

12mm mandibular

12.5mm maxillary posteriorly and 14mm anteriorly

most overdenture attachments work well in class _____, but bar and clip systems must be carefully designed to fit optimally within a denture base of physiologically acceptable contour

II

how much restorative space is needed for class III overdentures?

9mm mandibular

9.5mm maxillary posteriorly and 10mm anteriorly

how much restorative space is needed for class IV overdentures?

5mm mandibular

5.5mm maxillary posteriorly and 7mm anteriorly

it has been recommended that a minimum of approx ___mm of vertical restorative space (crest of bone to occlusal plane) is necessary to accomplish a mandibular implant retained overdenture

most class ____ pts may not be candidates for overdenture therapy

12

III

why is keratinized tissue important in implant-retained overdentures?

provides a stable and resilient peri-implant mucosa

facilitates oral hygiene and plaque control

reduces soft tissue inflammation and gingival hyperplasia

improves pt comfort and tolerance of attachments

contributes to long term peri-implant soft-tissue health and prosthesis stability

how many implants is ideal for a tissue supported dental prosthesis in the maxilla without palatal coverage?

minimum of 4 equidistant

positioning the implants in the anterior maxilla, mesial to the first premolars, enhances the stability of the overdenture

how many implants is ideal for a tissue supported dental prosthesis in the mandible?

2 provide excellent long term success and survival, including pt satisfaction and improved overdenture

CBCT and computer based planning

visualization of osseous structures in various 3D and cross sectional perspectives

visualization of the planned prosthesis in 3D and its relationship to underlying bone

visualization of available restorative space in 3D to assist in prosthesis design and attachment selection

virtual placement of dental implants in bone

fabrication of accurate and stable surgical templates

surgical guide

used for imaging and surgical purposes

fabricating a good template would enhance the diagnostic value of imaging and then guide the successful placement of the implant

what are the types of surgical guides, and which is most accurate?

bone supported, mucosa supported, teeth supported (most accurate)

attachment systems for implant overdentures consist of __ parts…

2

matrix and patrix

what are the different attachment assemblies?

telescopic copings

studs

clips and bars

magnets

what are the parts of stud attachments?

ball attachment

extra radicular attachment (ERA)

locator attachment

stud attachment provides _____ to ____ % load relief to the supporting implants

75 85

what are the design features of locator overdenture attachments?

self alignment

dual retention

pivoting feature

dual retention males

20 degrees of divergence

blue 1.5 lbs, pink 3lbs, white 5lbs

extended range males

40 degrees of divergence

grey 0lbs, red 1lb, orange 2lbs, green 4lbs

locator R-Tx

up to 60 degrees of divergence

what are the advantages of using stud attachment (locator system)?

can be used in cases of limited inter-arch space

can accomodate inter-implant angulations up to 60 degrees

what are the disadvantages of using stud attachment (locator system)?

they cannot be used in cases where rigid restoration is required

regular replacement of the nylon part due to constant wear and tear

*how should you determine the gingival height for locator attachments?

measure gingival height from the implant platform to the tissue crest using a perio probe

select cuff based on gingival height

if heights differ, pick the ‘tallest’

incorrect cuff height can result in reduced retention or soft-tissue compression and inflammation

*what makes up the 8-10mm of restorative space needed for the locator?

denture base and teeth- 4-6mm

metal housing- 3mm

locator- 1.5mm

what are the types of fabrication process for bar attachments?

prefab

castable pre-milled plastic pattern

what are the types of cross-sectional shapes for bar attachments?

round

egg

parallel sided (U shaped)

what are the types of resiliency for bar attachments?

resilient, non-resilient

what are the types of bar attachments?

hader attachment

dolder attachment

hader attachment

hing resilient attachment

provide almost 30-35% load relief to the supporting implant

dolder attachment

combination resilient attachment

offers 40-45% load relief to the supporting implants

what are the general rules of bar arrangement?

the bar should be perpendicular to the line that bisects the angle formed by the two posterior mandibular arch segments

the AP distance rule is good for determining the distal cantilever extension

generally the distal cantilever should not exceed 1.5 times the AP distance

vertical relationship of bar to the alveolar ridge

wide gap of >2mm for good oral hygiene

small gap of <1mm bad for oral hygiene

compression of the mucosa by the bar will lead to hyperplasia of the gum

sagittal relationship of the bar to the alveolar ridge

if the bar is lingual to the crest of the ridge there will be interference with tongue space

if the bar is labial to the crest of the ridge there will be interference with lip support

the bar should be positioned directly above the crest of the ridge

*what makes up the 14-16 mm of restorative space needed for the bar?

5mm denture tooth

2mm denture base

1mm metal housing

2mm clip thickness

5mm bar height

1-2mm space under the bar

tldr pt satisfaction comparing bar group and locator group

bar had slightly higher implant survival

bar had greater pt satisfaction

no difference in hygiene and soft tissue condition

locator group had 0.27mm more marginal bone loss

don’t forget to put a separator in the undercut of an abutment when doing a pick up impression!

got it! yay! sides 64-65

*what are the mechanical complications of implant supported over dentures?

30% loss of retention/adjustments

19% overdenture relines

17% clip/attachment fractures

12% overdenture fracture

12% acrylic resin fracture

3% metal framework fracture

*what are the mechanical complications of implant retained mandibular over dentures?

sore spot/ulcerations

inadequately retentive ball housings (lost/loose ball housings from denture)

relines

replace broken/debonded anterior and posterior teeth (residual wax on the prosthetic teeth was not appropriately removed)

denture base repairs (most frequently mandibular midline fractures)

abutment tightening

abutment replacement

is there a difference in ball vs bar anchorage?

no signficant differences could be detected

what is the suggested follow up protocol for mandibular implant overdentures?

control of occlusion- for better distribution of contacts in centric occlusion as well as during eccentric movements

cantilever lengths- should be minimized

controlling prosthetic components- such as by respecting manufacturer screwing guidelines

replacing the attachment- every year (at least the internal part) to maintain articulated connection between implants and denture

relining procedure- to anticipate first 5 yrs (as soon as denture default is observed)

recall appts- evaluate regularly for denture integrity and servicability

new denture fabrication- if new denture has to be fabricated within 5 yrs of service success was not achieved- however after a decade a remake should not be considered a failure

on average, the longevity of overdenture prosthesis was ___ years, and lab relining was every ___ years

prosthetic maintenance included…

12

4

fractured components, denture relining, replacement of prothesis

peri-implantitis

12.4% of the implants in 37% of pts exhibited radiographic symptoms

the bar design might explain the comparatively high rates in this study- it may lead to reduced accessibility for oral hygiene procedures at home

tldr this entire ppxt

__ implant supported overdenture should be the minimum requirement of treatment for mandibular complete edentulous cases

a minimum number of implants to support a maxillary overdenture is ____

it is important to diagnostically evaluate _______ before implant placement- failure to do so accurately may result in estheticially and structurally compromised prosthesis and pt dissatisfaction

there is ____ evidence for one outstanding system- the choice should be oriented towards the individual _________, _______, and the ________

2

4

available restorative space

no, clinical situation, individual needs of the pt, choice of the clinician