Implant Occlusion.pptx

Dr. Vikranth Ravipati
Comprehensive Dentistry

KimY
,Oh T
,Misch C,Wang H.Occlusal considerations in implant therapy: clinical guidelineswith biomechanical rationale..Clin Oral Impl Res2005;16:26-35

Teethintrude 25-100 microns
Implants intrude 3-5 microns
KimY
,Oh T

The lack of PDLmakesa largedifference in detecting early phase
of occlusal force between teeth and implants
Natural teeth canperceive aninterference at approx 20microns,
vsimplants(48microns)
Jacobs& vanSteenberghe.Comparison between implant-supported prsthesis andteeth regarding passivethreshold level. Int J
Oral
Maxillofac Impl 1993;8:549-554

Implants lack periodontal receptors andaremore susceptible to
occlusal overloading because:
-lack of load-sharing ability
-adaptation to occlusal force
-reduced mechanoreceptors
KimY
,Oh T

Complete implant fixed prosthesis do not have propioception
Patients bite with 4x more force than with natural teeth
Misch C. Contemporary Implant Dentistry. St. Louis,

Large cantilevers
Parafunction
Premature contacts
Improper occlusal scheme( excessivelateral load)
KimY
,Oh T

• 14 studies were included for review
• 11/14 were animalexperimental studies
• Humans:casereports andretrospective
studies
MichaelChangetal.JInvestigClinDent. 2013;11:156-158

• Animal studies:
- Complete loss of osseointegration or marginal
bone loss hasbeenshown in few animalstudies.
Inconclusive results.
- Consistently shown that functional load
increasesremodeling activities around implants
which canincrease BIC andbone density

• Human studies
- Repeatedlyshown marginal bone loss and
possible lack of osseointegration of implants
with increased occlusalload
- However, these are retrospective studies and
other factors canbeconsidered

Evendistribution of occlusal contacts avoiding occlusal
interferences andincreasingnumber of implants may
significantly reduce occlusal overload on implants andimplant
prosthesis
Poor bone quality maybemore vulnerable to occlusal
overloading, which canbereduced by extending healingtime
andcarefully monitored loading (progressive or delayed
loading)
SchwarzM. Mechanical complications of dental implants. Clin Oral Impl Res2000;11(suppl):156-158

Bilateral stability in centric (habitual) occlusion
Evenlydistributed occlusal contacts and force
No interferences between retruded position and centric
Narrow occlusal table (30-40%more narrow): reducesoffset
loading andincreasesaxialloading

Wide freedom in centric occlusion
Anterior guidancewheneverpossible
Smooth, even,lateral excursive movements w/o working/non-
working interferences
Placeposterior implant crowns in crossbite if necessaryto create
axial loading

Occlusal adjustments could beperformed by elimination of
mobility difference between implants andteeth under heavy bites
This evenlydistributes loadsbetween implants andteeth
Over time, teeth changeposition in vertical andmesialdirections,
while implants do not changeposition. Also, enamelwearsfaster
than porcelain. Therefore, periodic occlusal adjustments are
imperative

Teeth designedfor long-axis loads
Natural roots perpendicular to curves of Wilson + Spee
Contact during mastication forces along long-axis of roots
Implants designedfor long-axis loads
Generates lessoverall stress
↑ Proportion of compressive stress compared to angled forces
Implant body should beperpendicular to curves of Wilson +
Spee
MischCE.Occlusal considerations for implant-supported prostheses: Implant-protected occlusion. Pp874-912. Dental Implant Prosthetics (2nd ed), MischCE.
2015. Mosby,Int.

Finite element analysis
All designssustained stress contours concentrated at the
crestal region of the implant
2015. Mosby,Int.

12° angled force
↑ force to the implant by 18.6%,21 N
↑ shear force
2015. Mosby,Int.

15 degreeaxial implant load to facial bone ↑ 25.9%
30 degreeaxial implant load to facial bone ↑ 50%
2015. Mosby,Int.

Boneisstrongest to compressive forces
30%weaker to tensile forces
65%weaker to shear forces
2015. Mosby,Int.

Bonestrength isdecreasedunder angled forces
↑ the angleof load ↓ strength of bone
2015. Mosby,Int.

Non-axially loaded implants
↑ Total force, ↑ Shearforce
↑ Riskof crestal bone loss
↑ Riskof porcelain fracture under shear force
↑ Riskof loss of cement retention dueto shearforce
↑ Riskof abutment screw loosening andimplant component
fracture under shear loads
2015. Mosby,Int.

Angled abutments should ONLY be used:
• Improve path of insertion of prosthesis
• Improve final esthetic result
2015. Mosby,Int.

P:Analyze stresses generated with different angulations to the long
axis of the implant, under axial andoblique loading by Finite Element
Modelling andAnalysis.
M+M:
Frontal region of maxilla modelled with a cortical layer 1.5 mmthick
with aninner cancellous core
Implant : cylindrical, round ended, 4.1x 13 mm.
Abutment : 7 mmheight with a 5 degree occlusal taper.
Abutment angulations : 0°, 10°, 15° and 20°.
Loadsused:100, 125, 150, 175 and200 N axially, and50 N in
oblique direction.
BahugunaR,Anand B,et al. Evaluation of stress patterns in bone around dental implant for different abutment angulations under axial andoblique loading:A
finite element analysis.Natl J
MaxillofacSurg.2013

R:
MaxillofacSurg.2013

BL:
As the abutment angulation ↑, there is an ↑ in both tensile and
compressive stresses yet they are within the tolerance limits
of the bone
Increase observed in both the axial and oblique loading
Care should be taken while planning a restoration to
minimize the oblique component of force
MaxillofacSurg.2013

A reduction in the force magnitude
Additional surface areaof implant support isindicated
Surgically:
1.Additional implant next to most angled implant
2.↑ Diameter of the angled implant
3.Selectimplant designwith greatest surfacearea
2015. Mosby,Int.

• A reduction in the force magnitude
• Additional surface areaof implant support is indicated
Restoratively:
1. Splinting implantstogether
2. Reducingocclusal load on angled implants
3. Eliminating all lateral or horizontal forces on angledimplants
2015. Mosby,Int.

Cantilevers are force magnifiers on implants, abutment screws,
cement or prosthesis screws, andimplant-bone interface.
Class I Lever- effort arm = length of cantilever
resistance arm distance b/w abutments
Misch.Treatment plans related to key implant positions andimplant number. Pp147-159. Contemporary Implant Dentistry, Misch,C.E., 3rd Edition, 2008,
Mosby.

2015. Mosby,Int.
Mechanicaladvantage= 20mm/10mm = 2
Force to cantilever 2 x Force on furthest abutment
Sumof forces on fulcrum abutment

2015. Mosby,Int.
Force on cantilever : compressive
Force on furthest abutment: tensile andshear
Force on closest abutment (fulcrum): compressive

Exceptions when cantilevers maybe acceptable
if low force factors and increased bone density:
Edentulous mandible with insufficient
bone in the posterior
Misch.Treatment plans related to key implant positions andimplant number. Pp147-159. Contemporary Implant Dentistry, Misch,C.E., 3rd Edition, 2008,
Mosby.

• Implant isloaded in long axis Crown height doesNOT
magnify force
• Lateral load, angledforce, or cantilever applied  Crown
height isa force magnifier (vertical cantilever)
– Load applied to occlusal table magnifiedby crown height
2015. Mosby,Int.

Crown height directly increaseseffect of angled force
100 N load at a12° angle21 N of lateral/shear force
15mm Crown x 21N force = 315 N-mm moment force
2015. Mosby,Int.

Immediaterestoration:A restoration inserted within
48hrs of implant placement but not in occlusion with the
opposing dentition
Immediateloading:A restoration placedin occlusion with
the opposing dentition within 48hrs of implant
placement
Earlyloading:A restoration is in contact with the
opposing dentition andplaced at least 48hrs after
implant placement but not later than 3 months

Delayed loading: The prosthesis is attached in a second
procedure that takes place later than the conventional
healingperiod of 3-6months
Cochran et al 2004

• Primary clinical stability of the implants
• Adequate implant splinting where appropriate
• Provisional restorations that promote splinting and
reduce or control the mechanical load applied to
implants
• Prevention of provisional restoration removal during
the healing period
Morton et al,2004

• High masticatory or parafunctional habits
• Poor bone quality

Biomechanical effects of the provisional restoration
should be controlled by :
1) limiting and distributing occlusal contact in
centric occlusion or maximum intercuspation
2) removing all excursive contacts from provisional
restorations
3) limiting the effects of cantilevers andoff-axial
loading
4) author recommends splinting implants whenever
possible
Morton et al 2004

No study demonstrates increase in parafunction after occlusal
adjustment
Benefit: decreaserisk of occlusal overload on particular teeth and
addedbenefit of perhapsreducing parafunction
Almost every patient diagnosedwith parafunction should
undergo occlusal analysisandadjustment if necessary

• Bruxism is a complex diseaseof multifactorial origin
for which treatment hasbeenshown to be ineffective
• Dental implants should not becontraindicated any
more than anyother form of restorative dentistry as
soon as the patient understands that his/her increased
risk of oral destruction is not something that the
dentist can control
Dental Implant Complications, Froum 2010

In partially edentulous patients, the maxillary nightguard canbe
relieved around the implant crowns so the remaining teeth bear
the entire load
A mandibular posterior cantilever on a full-arch implant
prosthesis mayalsobetaken out of occlusion with a maxillary
night guard
Soft reline material maybeplacedaround the implant crowns to
act as a stress relief element (or night guardmaybemade
shorter, not including the cantilever)

•Lackof available bone for implant placement
•Pt’s unwillingness to undergo augmentation
procedures
•Inadequate diagnosisandtreatment planning
with the restorative dentist

• Ceramic fracture
• Screwloosening / fracture
• Implant fracture

Implant Occlusion.pptx

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