Dental Implants have changed the face of dentistry over the last 25 years. What are dental implants? What is the history of dental implants? And how are they used to replace missing teeth? This section will give you an overview of the topic of dental implants, to be followed by more detail in additional sections.
As with most treatment procedures in dentistry today, dental implants not only involve scientific discovery, research and understanding, but also application in clinical practice. The practice of implant dentistry requires expertise in planning, surgery and tooth restoration; it is as much about art and experience as it is about science. This site will help provide you with the knowledge you need to make informed choices in consultation with your dental health professionals.
Dental Implants
Dental illustration by Dear Doctor
Let’s start from the beginning: A dental implant is actually a replacement for the root or roots of a tooth. Like tooth roots, dental implants are secured in the jawbone and are not visible once surgically placed. They are used to secure crowns (the parts of teeth seen in the mouth), bridgework or dentures by a variety of means. They are made of titanium, which is lightweight, strong and biocompatible, which means that it is not rejected by the body. Titanium and titanium alloys are the most widely used metals in both dental and other bone implants, such as orthopedic joint replacements. Dental implants have the highest success rate of any implanted surgical device.
Titanium’s special property of fusing to bone, called osseointegration (“osseo” – bone; “integration” – fusion or joining with), is the biological basis of dental implant success. That’s because when teeth are lost, the bone that supported those teeth is lost too. Placing dental implants stabilizes bone, preventing its loss. Along with replacing lost teeth, implants help maintain the jawbone’s shape and density. This means they also support the facial skeleton and, indirectly, the soft tissue structures — gum tissues, cheeks and lips. Dental implants help you eat, chew, smile, talk and look completely natural. This functionality imparts social, psychological and physical well-being.
10. Implant Length
Length directly
proportional to surface
area
Greater bone to implant
contact
11. Longer implant- greater surface area-
greater stability
Favorable crown/implant ratio
Longer implants >10 mm compatible
with CSR
(Adell 1982, Lee 1995)
12. D1 bone- bicortical stabilization
unnecessary as bone is homogeneous
D2 , D3 bone- bone over heating
D4 bone- apical areas too soft for local
compression stabilization
19. Wide Body Implants
> 5mm in diameter
(Vanderweghe, Ackernman A, 2009)
95.7% survival rates
Used as rescue implants
extraction sockets in poor primary stability
poor bone quality
20. NDI implants
<3.75 mm in dia
(Arisan V, Bolukbusu 2010)
Overdenture in mandible
94-100% survival rates
Follow up- 1-9 years, CSR .95%
(Cho CS, Froum S)
21. Impact of length and diameter
(Renourd F, Nisand D, 2006)
Dense bone, textured implants, good
operator skill – short, wide, implants had
same survival rates as traditional
implants
22. Influence of diameter and length on
early implant loss
(Olat e S, Lynn MC, 2010)
Early implant loss associated with short
implants
Not associated with diameter
23. Ultra short implants 5mm long, 5mm in
diameter in posterior areas
(Deport er D,2008)
1-8 year follow up results
Maxillary, mandibular failure rates 14.3
and 0%
30. Implant Threads
Screw threads
tapped
self tapping
Solid body press fit
Sintered bead technology
31. Thread Geometry
Increase bone implant contact area
○ Total vs functional surface area
Stress distribution
Stability
32. Bone bridge from one thread to another
Cusp like bone formation
Heterogenous stress field
33. Thread shapes available include; V-shape,
square shape, buttress and reverse buttress
shape (Boggan et al. 1999).
34. Bone implant contact-
increased in square threads
(Steinganga,2004)
Density highest below threads
Weakest- tip of threads
(Bolind,2005)
35. • Square, Buttress threads
◦ Axial load - dissipated
through compressive force.
(Bungar dener ,
2000)
V shaped and reverse
buttress
◦ Axial load – dissipated
through compressive,
tensile and sheer force.
( Misch, 2005)
36. Cancellous bone
V shaped, broad square threads
Significantly less stress
Cortical bone
No difference
(Geng 2004)
Square thread least stress concentration
(Chun et al 2000)
37. The face angle is
the angle between a
face of a thread and
a plane
perpendicular to the
long axis of the
implant.
38. • Face Angle
Shear stress increased as face angle
increases
V shaped, 30°
Reverse buttress 15°
V shaped, buttress
Generates excess forces
Defect formation
(Hansson & Wer ke 2003)
39. • Thread pitch refers to the
distance from the center
of the thread to the center
of the next thread,
measured parallel to the
axis of a screw (Jones
1964).
• It may be calculated by
dividing unit length by the
number of threads (Misch
et al. 2008).
40. Thread pitch
Maximum effect on design variables
Affects surface area
Lower pitch- increased % BIC
Less pitch- deceased stress
(Motoyosti, 2005)
41. .8 mm pitch optimal for primary stability
*V shaped threads
Shorter or longer pitch
* Unfavorable forces
Affects cancellous more than cortical
bone
42. Thread depth is defined as the distance
from the tip of the thread to the body of
the implant.
Thread width is the distance in the same
axial plane between the coronal most
and the apical most part at the tip of a
single thread.
43. Thread depth & width
Affects implant surface area
Deeper the thread- wider surface area of
implant
Shallower thread- ease of placement
44.
45. Progressive thread design
Greater depth apically, decrease
gradually in a coronal direction
Increased load transfer to more flexible
cancellous bone
Decreased cortical bone resorption
46. Optimal thread depth - .34-.5mm
Thread width- .18- .3 mm
Depth more sensitive to peak stresses
(Abrahamsson, 2010)
56. Physicochemical properties
Zeta potential
○ Difference in potential between tightly bound
layers and diffuse layers
Interfacial tension
Wettability- property of interaction forces
between different materials and interaction
between cohesion forces within materials
(Mollers)
57. Low wettability- low osteoblast cell
attachment and decreased collagen
production (Reddy 2000)
Increased polar components –
increased osteoblast function
58. Electrostatic interaction in biological
events -conducive to tissue integration.
(Baier RE et al., 1998)
No selective cell adhesion
Does not increase implant tissue
interface strength
(Puleo DA et al., 2006)
60. Surface Roughness
Increased surface area of implant
adjacent to bone.
Improved cell attachment to bone.
Increased bone present at implant
interface.
Increased biochemical interaction of
implant with bone.
61.
62. • Smooth surfaces: Sa value < 0.5 μm (e.g.
polished abutment surface)
• Minimally rough surfaces: Sa value 0.5 to <
1.0 μm (e.g. turned implants)
• Moderately rough surfaces: Sa value 1.0 to
< 2.0 μm (e.g. most commonly used types)
• Rough surfaces: Sa value ≥ 2.0 μm (e.g.
plasma sprayed surfaces).
(Wenner ber g and Albr ekt sson,
2009)
63. • Moderate roughness and roughness is
associated with implant geometry-
allowed for bone ongrowth and provided
mechanical interlocking (Berglungh et al.
2003, Franchi etal. 2005)
• Higher BIC and removal torque force
suggested enhanced secondary stability
compared to smooth and minimally
rough implants (Buser et al. 1991,
Wennerberg etal. 1996).
64.
65. Morphology
Based on texture
Concave texture (mainly by additive
treatments like hydroxyapatite (HA) coating
and titanium plasma spraying)
Convex texture (mainly by subtractive
treatment like etching and blasting)
66. Based on the orientation of surface irregularities
Isotropic surfaces: have the same topography
independent of measuring direction.
Anisotropic surfaces: have clear directionality and
differ considerably in roughness.
76. Loading Protocol
Immediate loading
First longitudinal trial (Shit man,1990)
Immediate , early loading in mandible
77. Esposit o, 2009
Immediate- within 1 week
Early- 1 week to 2 months
Conventional- > 2months
78. Immediate and early can be done with
good success
* case selection
* operator skill
Failure rates:
early> immediate > conventional
Primary stability- very important
79. Esposit o, 2007
Differences between immediate & early:
not clear
More studies needed
80. Esposit o, 2004
Successful in mandible, dense bone
Few well controlled RCT’s.
81. Publication bias in immediately loaded
implants
(Polson, 2000)
Trial aborted in UK due to unacceptable
failure rate
83. Large , multicentric trial
(Donat i, Zollner,
2008)
Insufficient information
Risk of bias
84. Platform Switching
Wide diameter implants-intro in late
1980s
Fitted with standard diameter
abutments- showed no changes in
crestal bone levels around implants
86. Long term studies (Wagenberg B 2010)
advantage of platform switching in
preserving crestal bone levels.
Recommended in anatomic sites where
minimum distance between implant and
adjacent units cannot be achieved.
87. Theories
1. Biomechanical theory
◦ Bone resorption limited by shifting stress concentration
zone away from crest and directing it along axis (Maeda
2007)
1. Placement of implant- abutment junction (IAJ) at
or below crestal bone level may cause vertical
bone resorption to reestablish biological width
(Hermann 2001).
2. Presence of inflammatory cell infiltrate at the IAJ
(Ericsson 1995) and Peri-implant microbiota.
88. Esposit o- SR, 2007
No evidence to show any implant better
than another
89. Implant survival rates
Popelet A,Valet F
63% DID NOT REPORT INDUSTRY
FUNDING
66%-RISK OF BIAS