Dental Implants- part I and II: Biological and surgical aspects

CONTENTS
• INTRODUCTION
• PARTS OF IMPLANT
• CLASSIFICATION
• BIOLOGICAL ASPECTS
a. Macrodesign- implant geometry
b. Microdesign
- History
- Additive processes
- Subtractive processes
- Hard and soft tissue interface

INTRODUCTION
- Per-Ingvar Brånemark (1950, Sweden)
- achieved an intimate bone-to-implant apposition that offered sufficient strength to cope with load
transfer called “osseointegration.”
• First edentulous patient treated (mandible)—1965 : inserted screw-shaped, commercially pure
titanium implants in the symphysis and left covered for a few months. Titanium abutments were
placed, on top of which a fixed prosthesis could be screwed within 6 months and lasted 40 years.
Brånemark et al. Osseointegrated implants in the treatment of the edentulous jaw: Experience from a 10-year period. Scand J Plast Reconstr Surg. 1977
Definition: 1. An alloplastic material or device that is surgically placed into the oral tissue beneath the mucosal or periosteal
layer or within the bone for functional, therapeutic, or esthetic purposes.
OR
2. To insert a graft or alloplastic device into the oral hard or soft tissues for replacement of missing or damaged anatomical
parts, or for stabilization of a periodontally compromised tooth or group of teeth. (Glossary of Periodontal Terms-8)

PARTS OF A DENTAL IMPLANT
(C.E. Misch & C.M. Misch, 1993)

CLASSIFICATION
A- Depending on their placement within the tissues
Endosseous
1. Root form
2. Blade (Plate) form
3. Ramus frame
Subperiosteal
1. Unilateral
2. Complete
3. Circumferential
Transosteal
1. Staple
2. Pin (single)
3. Multiple pin

B- Depending on the materials used
• Metallic implants – Titanium, Titanium alloy, Cobalt Chromium Molybdenum alloy.
• Non- metallic implants – Ceramics, Carbon etc.
 PEEK implants
CLINICAL ADVANTAGES of PEEK over Ti:
i. causes fewer hypersensitive and allergic reactions.
ii. radiolucent –fewer artifacts on magnetic resonance
imaging
iii. Non-metallic appearance– more aesthetic
iv. versatile foundation material– can be tailored to a
particular purpose by changing its bulk or surface
properties.
(Rahmitasari et al., 2017)

C- Depending on their reaction with bone
• Ceramics: hydroxyapatite, fluorapatite, tricalcium phosphate, Bioglass, carbon silicon
BIOACTIVE
• Metals: commercially pure titanium and titanium alloys. Ceramics: Aluminium oxide,
zirconium oxide
BIOTOLERANT
• Metals: gold, Co-Cr alloys, stainless steel, zirconium, niobium. Polymer: polyethylene,
polyamide, polyurethane, polyamide
BIOINERT

D- Depending on treatment options (Misch’s Classification, 1989)
• FP- 1: Fixed prosthesis; replaces only the crown; looks like a natural tooth.
• FP- 2: Fixed prosthesis; replaces the crown and a portion of the root; crown contour appears normal in
the occlusal half but is elongated or hyper contoured in the gingival half.
• FP- 3: Fixed prosthesis; replaces missing crowns and gingival color and portion of the edentulous site;
prosthesis most often uses denture teeth and acrylic gingival, but may be made of porcelain, or metal.
• RP-4: Removable prosthesis; overdenture supported completely by implant.
• RP-5: Removable prosthesis; overdenture supported by both soft tissue and implant.

MACRODESIGN OF IMPLANTS
Implant Geometry
BIOLOGICAL ASPECTS

BLADE IMPLANTS
• Given by Linkow (1968)
• One or several posts pierced through the mucoperiosteum after suturing of
the flaps
- DISADVANTAGES:
1. Because the high-speed drilling leads to ample bone necrosis at the
histologic level, fibrous scar tissue formation occurs. This allows
downgrowth of the epithelium, which leads to marsupialization of the
blade implants.
2. If a bacterial infection occurs, it can lead to an intractable
periimplantitis with ample bone loss.
3. removal of such implants after complications implies sacrificing
surrounding jawbone.
4. Because of its retentive geometry, the blade implant cannot simply be
extracted or removed by a trephine, as with a cylindrical or screw-
shaped implant.

PINS
- Seldom used at present
- DISADVANTAGE: Similar to blade implants, the bone necrosis during
drilling leads to fibrous encapsulation, marsupialization, and loss of the
implants because of infections.
- ADVANTAGE: when such implants must be removed, removing the
connection at the place of convergence is sufficient to allow easy extraction of
each individual pin. Thus, bone loss from removal is minimal.

CYLINDRICAL IMPLANTS
• 2 types- HOLLOW and FULL.
- Straumann et al, 1970: ITI (International Team for Implantology)
system hollow cylinders
- Rationale: Implant stability would benefit from the large bone-to-
implant surface provided by means of the hollow geometry.
- The holes (vents) were believed to favor the ingrowth of bone to offer
additional fixation.
- Similar concept: Core-Vent system (Niznick, 1982)
- Studies showed disappointing survival statistics with the hollow
cylinders. (Piatelli, 1999; Telleman, 2006)
- Full cylindrical implants (Kirsch, 1989) marketed as IMZ, referring to
the “internal mobile shock absorber.”
- Although early results were encouraging (symphyseal area), the long-
term survival rates became unacceptable (Willer, 2003; Park, 2005)—
limited use currently.

DISK IMPLANTS
- Rarely used currently. Given by Scortecci (1999)
- Rationale: lateral introduction into the jawbone of a pin with a disk on top. Once introduced into
the bone volume, therefore, the implant has strong retention against extraction forces.
- DISADVANTAGE: cutting of the bone by means of high-speed drills leads to a fibrous scar tissue
surrounding the implant, as revealed frequently by peri-implant radiolucencies.
- Data on the clinical success of disk implants are mostly anecdotal.

SCREW-SHAPED (Tapered) IMPLANTS
- Currently, the most common implant is the screw-shaped, threaded
implant.
- Currently discussion is ongoing about the ideal thread profile (mostly in
vitro or finite element analysis studies)
- Very good long-term (>15 years) clinical data available for a screw-
shaped implant (Brånemark system)—Ravald et al, 2013; Winitsky et al,
2018
- Decrease in interthread distance at the coronal end of the implant has
been shown to enhance the marginal bone level adaptation
- Tapered implant forms have been used primarily because they require
less space in the apical region
- No clinical data tend to support a superior success rate with tapered
versus straight oral implants.

SUBPERIOSTEAL IMPLANTS
- customized according to a plaster model derived from an impression of the
exposed jawbone, prior to the surgery planned for implant insertion.
- Several posts, typically four or more for an edentulous jaw, are passed through the
gingival tissues.
- designed to retain an over-denture, although fixed prostheses have also been
cemented onto the posts.
- DISADVANTAGES:
 As a result of epithelial migration, the framework of subperiosteal implants usually
becomes surrounded by fibrous connective tissue (scar), including the space
between the implant and the bone surface.
 The marsupialization, as described earlier, often leads to infectious complications,
which often necessitates removal of the implant.
 while being loaded by jaw function, jawbone resorption occurs rapidly, resulting in
a lack of adaptation of the frame to the bone surface.
 now rarely used.

TRANSMANDIBULAR IMPLANTS
- developed to retain dentures in the edentulous lower jaw.
- applied through a submandibular skin incision and required general anesthesia. Two models were
available.
- First “Staple-Bone” implant (Small, 1975)
- reported implant survival rate >90% after 15 years
- Bosker model (1989)
- less reliable, achieving only 70% survival after 5 years in the symphyseal areas as seen in the follow-
up analysis

MICRODESIGN OF IMPLANTS
Implant surface characteristics
- key element in the reaction of hard and soft tissues to an implant
- Some materials can have
 toxic cellular side effects
 bio-compatibility – “passive” tissue-healing
 enhance bone apposition at the implant surface in an osteoconductive manner.

HISTORY
 Before Brånemark clarified osseointegration, researchers
focused on surface characteristics to obtain bone
apposition.
 Titanium, preferably commercially pure (CP) titanium,
became the standard for endosseous implants (1981) in
periodontology.
 Ti is a very reactive material – undergoes instantaneous
surface oxidation creates a passivation layer of titanium
oxides, which have ceramic-like properties, making it very
compatible with tissues.

ADDITIVE PROCESSES
1. Modification of the chemical nature of the implant surface by coating its surface. E.g., hydroxyapatite (resembles bone tissue).
o Osteoblastic cell response—varies acc. to Ca : PO4 ratio (in vitro studies—Boyan 2016, MacBarb 2017)
2. Use of increased or modified titanium oxide (TiO2) layers –enhance/accelerate osteogenesis (Huang et al, 2005).
o This is achieved by anodizing or chemical processing.
o The oxide content of the TiO2 layer is essential for nucleation processes to form calcium phosphate precipitates mineralized bone formation.
3. Another line of research involves integrating fluoride in the TiO2 layer.
o These ions can be displaced by oxygen originating from phosphates, thus achieving a covalent binding between bone and implant surface. Hall
et al, 1995
o Fluoride release is also known to inhibit the adhesion of proteoglycans and glycoproteins on the hydroxyapatite surface, two macromolecules
known to inhibit mineralization. Embery & Rolla, 1980

SUBTRACTIVE PROCESSES
- These are the manufacturing processes to obtain a proper implant surface vary from machining (called “turned” for
screw-shaped implants) to acid etching and blasting.
- It is not known what degree of micro-roughness is ideal for bone adhesion; this depends greatly on the chemical
nature of the implant. (Ellingsen, 1991)
- Acid etching and blasting alter the microroughness of the implant surface. Their effect cannot be limited to this,
however, because these processes can also modify the surface chemistry to a certain extent. Nevertheless, their
impact on surface roughness predominates, which is why they are applied.

IMPLANT SURFACE CHEMICAL COMPOSITION
- Studies on oral implants made of carbon or hydroxyapatite—so far unsuccessful. (Ong et al,
2000)
o lack of resistance to occlusal forces frequent fractures.
o So-called noble metals or alloys, on the other hand, do not resist corrosion and have thus been
abandoned.
o vast majority of oral implants are made of commercially pure (c.p.) titanium, this type is the
focus of ongoing clinical research and discussion.

PROPERTIES OF TITANIUM IN DENTAL IMPLANTS
- Highly reactive metal that oxidizes within nanoseconds when exposed
to air- passive oxide layer corrosion resistance in c.p. form.
- Ti6Al4V (for titanium-aluminum 6%, vanadium 4%) –provoke bone
resorption because of leakage of some toxic components.
- The oxide layer of c.p. titanium reaches 10 nm of thickness. It grows
over the years when facing a bioliquid. It consists mainly of titanium
dioxide.
- All titanium oxides have dielectric constants, which are higher than for
most other metal oxides.
- The biomolecules normally appear as folded-up structures to hide their
non-soluble parts, while putting water-soluble radicals on their surface.
Thus, they will adhere to the TiO2 surface after displacing the original
water molecules sitting on its surface.
- Initially—weak van der Waals forces are acting, the high dielectric
constant of titanium oxides and the polarizability of the molecules after
adsorption will lead to high bond strengths, which are considered
irreversible when they surpass 30 kcal/mol. (Kasemo, 1983)
- To date, clinical results with CaP-coated implants have not been
encouraging in a long-term perspective. (Block and Kent, 1994; Lopez-
Valverde, 2021)
• For good-quality bone, after 15 years of follow-up, clinical success rates
of 99% have been reported for implants with a turned surface (Lindquist
et al, 1996)
• Enhanced implant surface characteristics are likely to be most beneficial
for the more challenging situations, such as poor-quality bone and early
and immediate loading.

SURFACE FREE ENERGY
 Surface free energy, or “wettability,” is an important parameter for these interactions—assessed through the
shape of a standardized drop of liquid put on the clean implant surface.
 The angle of this drop toward the underlying surface reveals that the cohesive forces between liquid
molecules are stronger than the adhesive forces between the liquid and the surface. Thus, a ball-shaped
drop would reveal a low surface free energy.

• Microscopic roughness at the cellular and molecular level is defined by surface topography—measured
with a profilometer, a stylus that follows the surface and measures the peak-to-valley dimensions
(expressed as Ra values) or the spacing between irregularities (expressed as Scx values)
• Roughened implant surfaces speed up the bone apposition
MICROSCOPIC ROUGHNESS

• (in vitro) more prostaglandin E2 (PGE2) and transforming growth factor beta (TGF-β1) are produced on
roughened than on smoother surfaces
• Roughened surfaces also show some disadvantages, such as increased ion leakage and increased adherence
of macrophages and subsequent bone resorption
• in vitro adsorption of fibronectin was higher on smooth than on roughened, commercially pure titanium
surfaces.—Francois, 1997
• Micro-topography also influences the number and morphology of cell adhesion pseudopods and cell
orientation.
• Grooves in an implant surface will guide the cell migration along their direction.
• Bone growth can enter altered microtopographic features such as pits and porosities with internal
dimensions that are only a few microns

STAGES OF BONE HEALING AND OSSEOINTEGRATION
- Any bone wounding  inflammatory reaction bone resorption activation of growth factors attraction by
chemotaxis of osteo-progenitor cells to the site of the lesion.
- In bone fracture, osteoblast differentiation  reparative bone formation fusion of both ends.
- In implant insertion into a prepared hole bone apposition onto the non-toxic implant surface.
- COUPLING effect: favors apatite crystal integration in the collagen network. E.g., osteocalcin (ECM protein)
modulates apatite crystal growth
- The material that offers the best biologic attachment to bone and gingival tissue is titanium – layer of TiO2
- The ability of a titanium rod to integrate into bone depends on
o host reaction to the surgical insult at the time of bone preparation
o ability to stabilize the rod during the early wound-healing stage.
- A threshold may exist in the amount of stability required of the implant in the early wound-healing process.
Cell Kinetics and Tissue Remodelling

INITIAL BONE HEALING
- Interface micromovements >150 mmno differentiation to
osteoblasts fibrous scar tissue formed between the bone and
implant surfacehence, occlusal load during the early healing
period should be avoided.
- neighboring bone has been overheated/crushed (critical temp =
47° C for 1 min—temp at which alkaline phosphatase
denatures—main osteocyte enzyme) during drilling
necroticprevent ingrowth of stem cells scar/sequestered
formation.
- profuse cooling with intermittent moderate-speed drilling with
sharp drills.
- Microbial contamination jeopardizes the normal bone repair
strict asepsis should be maintained.
- Initially, immobility of the implant surface toward the bone should be maintained.
- mild inflammatory response may enhance the bone-healing response, but detrimental above a certain threshold.
- For proper healing, the limited damage to bone tissue must be cleared
up by osteoclasts—these resorb bone at a pace of 50 to 100 mm per day.
Hence there is a coupling between bone apposition and bone resorption
- pre-osteoblasts (from invading primary mesenchymal cells) depend on
a favorable redox potential of the environment-- requires proper
vascular supply and O2 tension
- If the favorable conditions are not met
- primary stem cells may differentiate into fibroblasts
- implant (or the bone fracture surfaces) will be facing scar
tissueimplants will eventually be connected to the outer
environment  potential for infection.

1) woven bone is quickly formed in the gap between the
implant and the bone.
 grows fast, < 100 μm/day, and in all directions.
 characterized by a random orientation of its collagen fibrils,
high cellularity, and limited degree of mineralization.
 Limited mineralization  bone's biomechanical capacity is
poor,  occlusal load should be controlled.
 Woven bone can grow by apposition, originating from the
bone lesion or by conduction, using the implant surface as a
scaffold.
 Factors influencing bone apposition: material properties,
surface free energy, and roughness profile.
 Altered implant surface topographies greater bone
apposition to the implant surface as compared to a “turned”
or machined surface.

2) After 1 to 2 months, this is progressively replaced by lamellar
bone
 under the load stimulation the woven bone surrounding the
implant will slowly transform into lamellar bone.
 Parallel layers of collagen fibrils characterize the latter, each
with their own orientation,
 occurs at a slow pace of a few microns per day.
3) A steady state is reached after about 1.5 years—occlusal load
is allowed as soon as 2 to 3 months (mostly woven bone).
• Research involving light microscopy has revealed an intimate
bone-to-implant contact

THEORIES OF OSSEOINTEGRATION
DISTANT OSTEOGENESIS CONTACT OSTEOGENESIS
Osteogenic cells line old the bone surface.
The blood supply to these cells is between the cells and
the implant.
Hence the bone is laid down on the old bone surface
itself.
Osteogenic cells are first recruited to the implant surface.
The blood supply is between the cells and the old bone,
hence new (de novo) bone is laid down.
FIBRO-OSSEOUS INTEGRATION (Linkow, 1970) OSSEOINTEGRATION (Branemark, Zarb, Albrektsson, 1985)
Fibro-osseous integration refers to a presence of
connective tissue between the implant and bone. If
osseointegration does not occur or osseointegration is
lost for some reason, a fibrous connective tissue forms
around the implant. organization process continues
against the implant material, possibly resulting from
chronic inflammation and granulation tissue formation &
osseointegration will never occur.
Osborn and Newesely (1980)
Theories regarding the bone-implant interface

PHASES OF OSSEOINTEGRATION
OSTEOPHYLLIC PHASE OSTEOCONDUCTIVE PHASE OSTEOADAPTIVE PHASE
Initially: hematoma between the
implant and the bone and only small
amount of bone is in contact with the
implant.
1 week: the body mounts a
generalized inflammatory response.
2 weeks: woven bone with primary
osteons has formed at the base of the
surgical site and also in the furcation
site of the implant surface.
4 weeks: newly-formed woven bone
which lines most parts of the implant
surface.
8 weeks: typical secondary osteons
with concentric lamellae and a central
Haversian canal can be observed in the
lamellar bone.
4 months: The bone cells lay down the
osteoid and spread along the metal
surface. The newly formed lamellar
bone, next to the implant, is
continuous with the more lightly
stained old bone tissue. In the apical
bone marrow part of the site, a thin
rim of lamellar bone can be seen in
contact with the implant surface.
When the implants are exposed and
loaded after 4 months, there is
reorientation of vascular pattern and
the woven bone thickens in response
to load transmission and thus bone
remodeling occurs.

BONE REMODELING & FUNCTION
Rigidity and Strength of Established Interface
• Factors determining success and survival of implant: primary and
secondary stability.
1. Primary stability is that which is achieved at surgery.
- depends on
o bone quality and available volume
o relation between drill and implant diameter
o implant geometry.
o quantity of bone-to-implant contact area.
2. Dense cortical bone (symphysis)  guarantees a rigid primary
fixation
- questionable with an eggshell cortex in the maxillary
tuberosity reflected in poorer clinical outcome observed for
implants in the posterior maxilla (Pabst et al, 2015).

3. Compressive stresses at the implant-to-bone interface : By using an undersized drill in soft bone for
preparation of the osteotomy site achieves a slight local compression, which enhances the initial stability of
the implant.
o can result in hoop stresses may lead to necrosis because of the compromised vascular supply and
microfractures.
4. Overloading: Longitudinal studies indicate that during the first weeks for one-stage implants, decreased
rigidity can be observed (Friberg, 1999). Subsequently, rigidity increases and continues to increase for years.
 “early bone resorption”
- Hence, when a prosthesis is installed immediately (in 1 day) or early (in 1-2 weeks), care must be
taken to control against overload.
- Overload (improper superstructure design or parafunctional habits)—cause microstrains and
microfractures  bone loss of the bone at the interface to fibrous inflammatory tissue.
5. Lack of load can also be detrimental and can lead to cortical bone resorption—called “stress shielding”.
Well- accepted in orthopedics, evaluation for dental implants pending research.

Swami V et al., Current trends to measure implant stability. The Journal of the Indian Prosthodontic Society. 2016 Apr
ASSESSMENT OF IMPLANT BIOMECHANICS
a. Non-invasive methods
i. The surgeon's perception: based on the cutting resistance and seating torque of the implant during insertion. A
perception of “good” stability may be heightened by the sensation of an abrupt stop when the implant is seated.
ii. Radiographical analysis/imaging techniques: numerous limitations–
• periapical or panoramic views do not provide information on a facial bone level—bone loss at this level precedes mesiodistal bone
loss.
• neither bone quality nor density can be quantified with this method.
• changes in the bone mineral cannot be radiographically detected until 40% of demineralization had occurred. (Wyatt and
Pharaoh,1998)
• Computer-assisted measurement of crestal bone level change may prove to be the most accurate radiographical information.
However, this method is not convenient to use in clinical practice.
iii. Cutting torque resistance (for primary stability): by Johansson & Strid, 1994– The amount of unit volume of bone
removed by current fed electric motor and is measured by controlling the hand pressure during drilling at low speed. It
determines areas of low-density bone and quantifies bone hardness during implant osteotomy at the time of implant
placement.

iv. Insertion torque measurement: mechanical parameter generally affected by a surgical procedure, implant
design and bone quality at the implant site. However, it cannot assess the secondary stability by new bone
formation and remodel around the implant.
v. Reverse torque: Johansson & Alberktsson, 1987. assesses the secondary stability of the implant. Implants
that rotate when reverse torque is applied indicate that bone-implant contact could be destroyed.
vi. Seating torque test: done after implant placement. Information about the primary stability of the implant
when the implant reaches its final apico-occlusal position.
vii. Modal analysis : vibration analysis, measures the natural frequency or displacement signal of a system in
resonance, which is initiated by external steady-state waves or a transient impulse force. It can be performed
in two models: Theoretical and experimental.
• theoretical modal analysis includes finite element analysis– vibrational characteristics of objects to calculate
stress and strain in various anticipated bone levels. It is used in clinical studies and experiments.
• experimental modal analysis is a dynamic analysis—measures natural characteristic frequency, mode and
attenuation-via vibration testing. It is used in nonclinical studies in vitro approach. It provides reliable
measurement
iv. Percussion test: simplest method. based upon vibrational-acoustic science and impact response theory.
clearly ringing “crystal” sound indicates successful osseointegration, whereas a “dull” sound may indicate no
osseointegration. Drawback: subjective.
v. Pulsed oscillation waveform (POWF): Kaneko, 1991. –analyze the mechanical vibrational characteristics of
the implant-bone interface using forced excitation of a steady-state wave. Resonance and vibration generated
from the bone-implant interface of an excited implant are picked up and displayed on an oscilloscope screen.
It is used for in vitro and experimental studies.

x. PERIOTEST
• Periotest (Gulden, Bensheim, Germany)
• projects a rod against the implant or abutment using a
magnetic pulse at a certain speed.
• The apparatus measures the deceleration time needed
before the rod comes to a standstill.
• This is transformed in an arbitrary unit, which reflects
the rigidity of the bone-to-implant continuum.
• Values should be below +7, the minimum, with the most
rigid being −8.

XI. Resonance frequency analysis (RFA)
- based on basic vibrational theory
- consists of a transducer that could be excited using a steady state,
swept frequency waveform and its response measured to determine the
stiffness of an implant in the surrounding tissues.
- designed to be attached to an implant or abutment
- performance was controlled using a dedicated frequency response
analyzer.
• originally used an L-shaped transducer that was screwed to an implant
or its abutment.
- Til date four generations of RFA have been introduced.
o Major drawback of the first- and second-generation RFA devices
was that each transducer had its own fundamental resonance
frequency.
o third-generation device provided a small battery-driven system,--
quick and simple measurements to be made with the possibility
of chairside interpretation.
o first commercially available RFA equipment OsstellTM,
Osstell AB, Gothenburg, Sweden) was battery-driven and had
new generation of transducer that was precalibrated from the
manufacturer. The results are presented as the implant stability
quotient (ISQ). The implant stability quotient unit is based on
the underlying resonance frequency and ranges from 1 (lowest
stability) to 100 (highest stability).
o The most recent version of RFA is wireless, where a metal rod (a
peg) is connected to the implant by means of a screw connection.

i. Histologic/histomorphologic analysis: obtained by
calculating the peri-implant bone quantity and bone-implant
contact (BIC) from a dyed specimen of the implant and peri-
implant bone. Used in the nonclinical studies and
experiments
ii. Tensional test: measured by detaching the implant plate
from the supporting bone. It was later modified by
Bränemark by applying the lateral load to the implant
fixture. However, they also addressed the difficulties of
translating the test results to any area independent
mechanical properties.
ASSESSMENT OF IMPLANT BIOMECHANICS
b. Invasive methods
iii. Push-out/pull-out test: investigates the healing capabilities
at the bone implant interface (Brunski et al, 2000). It
measures interfacial shear strength by applying load parallel
to the implant-bone interface. In the typical push-out or
pull-out test, a cylinder-type implant is placed
transcortically or intramedullarly in bone structures and
then removed by applying a force parallel to the
interface. Only applicable for nonthreaded cylinder type
implants and technique sensitive.
iv. Removal torque analysis: Removal torque analysis
implant is considered stable if the reverse or unscrewing
torque was >20 Ncm. DISADVANTAGE: at the time of
abutment connection implant surface in the process of
osseointegration may fracture under the applied torque
stress.

RECENT ADVANCES
i. Implatest: (Lee SY, Huang HM, Lin CY, Shih YH J
Periodontol. 2000 Apr)
- incorporates all of the features of a conventional impulse
test into a compact, portable, self-contained probe.
- Data can be gathered in seconds
- operator independent.
ii. Electromechanical impedance method: Boemio et al,
2011.
- utilizes the electro-mechanical impedance of
piezoelectric materials (work as both sensors and
actuators)
- directly related to the mechanical impedance of the host
structure.

iii. Micro motion detecting device: Freitas et al, 2012.
- customized loading device, consisting of
- a digital micrometer (Mitutoyo Absolute Digimatic,
USA) and
- a digital force gauge (Chatillon E-DFE-025, USA)
(range of 10–2500 N 0.25% resolution over range) is
used to determine implant micromotion.
- The forces are achieved by turning a dial, which controlled
the height of the force gauge. This dialed-in force is
applied to the abutment via a lever.
- The digital micrometer is placed tangent to the crown of
the abutment and detected the displacement after the load
application
iv. Highly non-linear solitary waves (HNSW): a
granular crystal functions as a combined sensor and
actuator
- composed of a chain of spherical particles in
contact with each other with a piezoelectric gauge
embedded in selected locations.
- Using the granular crystal, the surface of an
implant with a single HNSW, and record the
signals reflected from the interface between the
granular crystal and the implant specimen under
inspection
- Application for dentistry pending research

EPITHELIUM
- interface between epithelial cells and the titanium surface
is characterized by the presence of hemidesmosomes and
a basal lamina.
- Histologically, studies indicate that these epithelial
structures and the surrounding lamina propria cannot be
distinguished from those structures around teeth—
Branemark et al, 1985
• capillary loops in the connective tissue under the
junctional and sulcular epithelium around implants appear
to be anatomically similar to those found in the normal
periodontium
• In health, this sulcular epithelium has a thickness of about
0.5 mm, which shows transmigration of
polymorphonuclear cells and more mononuclear cells

- Between the epithelial attachment and the marginal bone is a
dense connective tissue with a limited vascularity in the
immediate vicinity of the implant surface.
- The total height of the “biologic width” is approximately 3-
4mm, where about 2 mm is the epithelial attachment and about
1 mm is the supracrestal connective tissue zone.
- Clinically, the thickness of the periimplant soft tissues varies
from 2 mm to several millimeters
- Epithelial downgrowth does not occur in a healthy situation,
indicating that factors other than collagen fiber bundles inserted
in the root surface control this downgrowth. The apical edge of
the epithelial attachment is about 1.5 to 2.0 mm of the bone
margin.
This means that the attachment level measurement performed with a
periodontal probe will be about 1.5 mm higher than the real bone
level.
- The average direction of the collagen fiber bundles of the
gingiva is parallel with the implant or abutment surface.
- Even when the fiber bundles are oriented perpendicularly
(gingiva), the bundles are never embedded in the implant
surface, as occurs with dentogingival and dentoperiosteal
fibers around teeth.
- The fiber bundles can also have a cufflike circular
orientation. The role of these fibers remains unknown but it
appears that their presence helps to create a soft-tissue
“seal” around the implant.
- At the biochemical level as well, there are no differences
between the peri-implant and the periodontal soft tissues,
even if some higher amounts of collagen types V and VI are
noticed.

VASCULAR SUPPLY and INFLAMMATION
- The vascular supply of the periimplant gingival or alveolar
mucosa is more limited than that around teeth—often reduced
due to lack of PDL.
- reaction patterns toward plaque at both the light microscopic
and the ultrastructural level are similar to those of tissues
surrounding teeth.
- periimplant gingival or alveolar mucosa has the same
morphology as the corresponding tissues around teeth. These
soft tissues also react the same way to plaque accumulation.
- Animal models have revealed that ligature-induced
periimplantitis occurs more frequently when alveolar mucosa
surrounds the implant as compared to when keratinized
mucosa surrounds the implant—Warrer, 1995—suggestive of
importance of adequate keratinized tissue width around
implants

- Microbial leakage:
o originates from the abutment-to-implant connection in 2-stage implants.
o Animal studies indicate that this leakage results in an inflammatory reaction in the adjacent lamina propria—(Lindhe, 1992)
o increase in the content of inflammatory cells may be due to the adhesion and the proliferation of bacteria at the level of the I-A
interface

o A gingivitis lesion surrounding an endosseous implant can be a contained, non-progressing lesion. A periimplantitis
lesion, on the other hand, is associated with a bacterial infection.
o Histologically, periimplantitis lesions demonstrate similarities with periodontitis lesions.
- They can be progressive
- lead to bone loss around the implant.
- Macroscopically rough implant surfaces, such as HA coated implants, seem to be associated with more significant
periimplantitis problems due to the propensity of these surfaces to harbor bacteria and perpetuate the infection. Whereas the
incidence of periimplantitis seems low with less rough (microscopically altered) implant surfaces even in the presence of
periodontitis in the remaining natural dentition.

COMPARISON OF TISSUES SURROUNDING NATURAL DENTITION AND OSSEOINTEGRATED ORAL IMPLANTS
Teeth Dental Implants
Periodontal fibers Insert into cementum on the root surfaces of
natural teeth
13 groups
Extend parallel to the surface of the implant
and/or abutment
2 groups
Connection Periodontal ligaments Osseointegration
Connective tissue Lower percentage of collagen fibers
Higher percentage of cells
More vascular
Higher percentage of collagen fibers
Lower percentage of fibroblasts. Looks very similar
to a scar tissue
Less vascular
Blood supply to surrounding
gingivae
Three different sources (the periodontal ligament
space, the interdental bone, and the
supraperiosteal region)
Two different sources (the supraperiosteal vessels
and a few vessels from the bone)
Periodontal ligament space Present Absent
Resistance to mechanical
and microbiological insults
More resistant Less resistant
Biological width (BW) JE: 0.97–1.14 mm
CT: 0.77–1.07 mm
BW: 2.04–2.91 mm
JE: 1.88 mm
CT: 1.05 mm
BW: 3.08 mm
Sulcus depth ≤ 3 mm when healthy Could be >3 mm depending on multiple factors
Proprioception Periodontal mechanoreceptors Osseoperception
Tactile sensitivity High Low
Axial mobility 25–100 μm 3–5 μm
Fulcrum when lateral force
applied
Apical third of the root Crestal bone
Possible relief Pressure absorption, distribution Pressure concentration on the crestal bone
(Rose LF, Mealey BL: Periodontics: Medicine, surgery, and implants, 2004)

SIGNIFICANCE OF A LACKING PDL AROUND IMPLANTS
1. No resilient connection exists between teeth and jawbone any occlusal disharmony will have repercussions at the
bone-to-implant interface.
2. No intrusion or migration of teeth can compensate for the eventual presence of a premature contact in cases of fixed
prostheses in both jaws.
3. Clinician should be reluctant to use oral implants in growing individuals as the neighbouring teeth and periodontal
tissues will further erupt occlusal disharmonies.
4. Problematic to place one or more implants in a location surrounded by teeth that are very mobile due to loss of
periodontal support, because as the teeth move away from the occlusal forces, the implant(s) will bear the entire load.
5. Reduced tactile sensitivity and reflex function—proprioceptive fibres in PDL
Concept of osseoperception
- Osseoperception can be considered an associated mechano-sensibility with osseointegrated implant rehabilitation
(Yan et al, 2008)
- For implant-supported prostheses opposing complete dentures, a contribution to oral kinesthetic perception could
come from the activation of mucosal receptors beneath the complete denture, and possibly periosteal and/or mucosal
mechanoreceptors in the vicinity of the implant fixture.
- The amount of Merkel cells in the gingival mucosa were found to be significantly higher in edentulous areas than in
the dentate mucosa. This increase in the number of Merkel cell population might be to compensate for the loss of
teeth. Studies have shown an increase in the tactile perception capability of osseointegrated implants over time
(Kingsmill et al, 2005; Muhlbradt et al, 1989; Mericske-Stern, 1998)
- Tactile function of oral implants: Neural receptors of the periodontium play an essential role in oral tactile function.
Most receptors, which are found in the PDL, are evidently absent around the perimucosa of dental implants. In those
cases, remaining receptors of the gingiva, alveolar mucosa, and periosteum may take over the role of normal
exteroceptive function.

CONTENTS
• SURGICAL ASPECTS
a. Case types and indications
b. Pre-treatment evaluation
c. General principles of implant surgery
d. 1-stage v/s 2-stage implant placement
e. Healing following implant surgery
f. Advanced implant surgical procedures
g. Post-treatment evaluation and management

CASE TYPES & INDICATIONS
SURGICAL ASPECTS

a. EDENTULOUS PATIENTS
Complete denture
Ceramic-metal fixed bridge
Separate attachments on individual implant
Clips etc. connected to a bar—splint the implants
together.
- patients prefer—ceramic restoration emerges directly
from the gingival tissues in a manner similar to the
appearance of natural teeth.
- DRAWBACKS: provide very little lip support—may
not be indicated for patients who have lost alveolar
bone height
- lack of a complete seal phonetic problems in speech

b. PARTIALLY EDENTULOUS PATIENTS
 Single Tooth.
- Greater chances of success and predictability of endosseous dental implants.
Reported success rates for single-tooth implants are excellent.
- Goodacre et al. performed Medline literature review from 1980-2001 and 2001-
17 and found the single-tooth implant success rate to be in the range of 97%—
higher than any other implant restoration.
- The greatest challenges to overcome with the single-tooth implant restorations
were
o screw loosening
o implant or component fracture.  due to increased potential to generate
forces in the posterior area
- Solution:
o use of wider-diameter implants –resists tipping forces  reduces screw
loosening. Also provides greater strength and #resistance due to increased
wall thickness (between the inner and the outer screw thread).
o internal fixation of components

 Multiple Teeth.
- Challenges from remaining natural dentition:
o occlusal schemes
o periodontal health status
o spatial relationships
o esthetics
- In general, endosseous dental implants can support a freestanding fixed
partial denture.
- Major advantage :
- not invasive to adjacent teeth—preparation of natural teeth unnecessary
- larger edentulous spans can be restored
• biggest consideration: underestimation of the importance of treatment
planning with regards to occlusal loads.  greater rate of multi-unit failures

I. Chief complaint
- problem or concern in the patient's own words?
- patient's goal of treatment, and how realistic are the patient's expectations?
- Patient reported outcome measures (PROMs)?
(Adapted from Tey et al., Clinical oral implants research. 2017)

II. Medical history
- At risk for adverse reactions or complications
- Any disorder that may impair the normal wound-
healing process
- A thorough physical examination
- Appropriate laboratory tests
- Medical clearance for surgery
III.Dental History
- history of recurrent or frequent abscessesmay
indicate a susceptibility to infections/diabetes
- multiple restorations
- compliance to past dental recommendations
- current oral hygiene practices
- previous experiences with surgery and prosthetics
- reported history of dissatisfaction with past
treatment

IV. Intraoral examination
General principles of implant placement:
Ideal implant measurements in posterior teeth
Ideal implant measurements in esthetic zone
 Minimum distance between implant margin to
adjacent tooth should be 1.5-2 mm
 Minimum distance between implants should be
3-4mm
 Buccolingually, should be placed at 2-3mm
from cervical height of contour
 Coronoapically, should be placed at 2.5-3mm
from bucco-gingival margin
 Atleast 7 mm of inter-occlusal/inter-arch space
should be available from the shoulder of the
implant to the occlusal surface of opposing
tooth
 A buffer zone of 2-3mm from IAN or floor of
sinus from implant apex should be maintained.
 maintain at least 1.0 to 1.5 mm of bone around
all surfaces of the implant after preparation and
placement. minimum of 12 mm in the posterior
mandible (mandibular nerve).

V. Diagnostic study models VI. Hard tissue evaluation
- amount of available bone
- Visual examination to identify deficient areas
whereas other areas that appear to have good ridge
width will require further evaluation.
- excellent means of assessing potential sites for dental
implants.
- evaluate the available space and to determine potential
limitations of the planned tx—particularly useful when
multiple teeth are to be replaced or when a
malocclusion is present.

VI. Initial radiographic screening
Indications:
1. Overall anatomy of the maxilla and mandible and
potential vertical height of available bone
2. Anatomical anomalies/pathological lesions
3. Sites where it may be possible to place implants without
grafting and sites that require grafting
4. Restorative and periodontal status of remaining teeth
5. Length, shape, angulation, proximity of adjacent roots
- Most common radiograph of choice: OPG (Palmer, 2012)
- The best way to evaluate the relationship of available bone
to the dentition is to image the patient with a diagnostically
accurate guide using radiopaque markers that accurately
represent the proposed prosthetic contours.

EVALUATION OF BONE DENSITY USING CBCT
Lekholm & Zarb 1985
Misch 1990, 1993

Newer modalities: INTERACTIVE “SIMULATION” SOFTWARE PROGRAMS
SIM/PLANT IMAGES

VII. Soft tissue evaluation
• Evaluation of soft tissue augmentation
In the presence of good oral hygiene, a lack of keratinized tissue does not impair the health or function of
implants.(Wennstrom et al, 1994)
keratinized mucosa has better functional and esthetic results for implant restorations. (Block et al, 1996)
Implants with coated surfaces (i.e., HA or TPS coating) demonstrate greater peri-implant bone loss and
failures in the absence of keratinized mucosa. (Kirsch & Ackermann, 1989)
Areas with minimal or no existing keratinized mucosa may be augmented with gingival or connective tissue
grafts.
Additionally, any mucogingival concerns, such as frenum attachments or pulls, should be thoroughly
evaluated.

GENERAL PRINCIPLES OF IMPLANT SURGERY

1. Patient preparation
- in-office procedure
- Under local anesthesia
- Prior explanation of procedural risks to patient
- Written informed consent
2. Implant site preparation
- Aseptic surgical site
- Pre-rinse with chlorhexidine gluconate for 30 seconds
Basic Principles of Implant Therapy to Achieve Osseointegration
1. Implants must be sterile and made of a biocompatible material (e.g., titanium).
2. Implant site preparation should be performed under sterile conditions.
3. Implant site preparation should be completed with an atraumatic surgical technique that avoids overheating of the bone during
preparation of the recipient site.
4. Implants should be placed with good initial stability.
5. Implants should be allowed to heal without loading or micromovement (i.e., undisturbed healing period to allow for
osseointegration) for 2 to 4 and 4 to 6 months in the mandible and maxilla, respectively.

• patients with good plaque control and appropriate occlusal forces have demonstrated that root form, endosseous dental
implants show little change in bone height around the implant. (Adell et al, 1981)
• After an initial remodeling in the first year that results in 1.0 to 1.5 mm of bone reduction (described as “normal
remodeling around an externally hexed implant”), the bone level around healthy functioning implants remains stable
for many years, allowing implants to be a predictable means for tooth replacement. The annual bone loss after the first
year in function is expected to be 0.1 mm or less.
• PRIMARY BONE CONTACT: After the osteotomy has been prepared, areas of the native bone structure are left
exposed. When the implant is placed into the preparation, some areas of the titanium rod make contact by “pressfit” to
the exposed native bone, called areas of primary contact.
- results in instantaneous osseointegration
- Bone formation begins to occur on the titanium surface and on the cut bone surfaces and trabeculae
• bone remodeling begins IN THESE AREAS—results in new bone formation along the implant surface
SECONDARY BONE CONTACT.
“dip” in implant stability

1-STAGE v/s 2-STAGE IMPLANT PLACEMENT SURGERY
 1-stage procedure: a component of the implant is projected above
the mucosa
 2-stage procedure: implant is initially covered with mucosa
- protection of the implant during osseointegration
- complex cases—poor bone quality or grafted regions
second-stage surgery exposes the top of the implant
abutment is attached.

CASE SELECTION OF IMPLANT PLACEMENT PROTOCOL

TWO-STAGE “SUBMERGED” IMPLANT PLACEMENT:
Stage 1 Surgical Procedure

• Flap design, incisions, and elevation
INCISIONS
i. Crestal incision: made along the crest of the
ridge, bisecting the existing zone of keratinized
mucosa
More preferred
Easy management
Less bleeding, edema
Faster healing
ii. Remote incision: when bone augmentation is
planned to minimize the incident of exposure
of bone graft

 FLAP REFLECTION
• Full-thickness flap -- buccally and lingually to the level of the
mucogingival junction, exposing the alveolar ridge of the implant
surgical sites.
• Elevated flaps may be sutured to the buccal mucosa or the
opposing teeth to keep the surgical site open during the surgery.
• The bone at the implant site(s) must be thoroughly debrided of all
granulation tissue.
• “Knife-edge” alveolar process  a large round bur is used to
recontour the bone to provide a reasonably flat bed for the
implant site.
• <10 mm of remaining alveolar bone, the knife-edge should
be preserved.
• Bone augmentation procedures can be used to increase the
ridge width .

• Implant site preparation—
- series of drills are used incrementally
- Surgical guide or stent may be used to direct proper implant placement
- Sequence of burs-
round
2-mm twist
pilot
3-mm twist
countersink

• multiple implants being placed next to one another use guide pin to
check alignment and parallelism
• IOPAR with a guide pin or radiographic marker in the osteotomy
site(s) to check relationship of osteotomy site to anatomical structures.
• Implants should be positioned ~3 mm between one another to ensure
sufficient space for
• interimplant bone and soft tissue health
• facilitate oral hygiene procedures.
• initial marks should be separated by at least 7 mm (center to center)
for standard-diameter implants

Sequential drilling:
HIGH speeds (800-1500 rpm) VERY SLOW speeds
(20-40 rpm)

• Implant placement
• At slow speeds (20-30 rpm)
• Either by rotating handpiece or manually by torque wrench
• Insertion must follow the same path as osteotomy site

• Flap closure & suturing
• surgical sites should be thoroughly irrigated with sterile saline.
• Proper closure of the flap over the implant(s) is essential. Good primary closure of the flap tension free.
• achieved by incising the periosteum (non-elastic)periosteum is released flap becomes very elastic able to be
stretched over the implant(s) without tension.
• combination of alternating horizontal mattress and interrupted sutures.
• Horizontal mattress sutures evert the wound edges and approximate the inner, connective tissue surfaces of the
flap to facilitate wound healing.
• Interrupted sutures help to bring the wound edges together, counterbalancing the eversion caused by the horizontal
mattress sutures.

• Postoperative care
• Simple implant surgery in a healthy patient usually does not require antibiotic therapy.
• Patients may be premedicated with antibiotics (e.g., amoxicillin, 500 mg tid) 1 hour before the surgery and continuing for 1
week postoperatively
• if the surgery is extensive
• if it requires bone augmentation
• if the patient is medically compromised.
• Postoperative swelling preventive measure: apply ice pack to the area intermittently for 20 minutes over the first 24-48
hours.
• Chlorhexidine gluconate oral rinses for plaque control, post-surgery.
• Adequate analgesics e.g., ibuprofen, 600-800 mg
• Instructions:
• maintain a relatively soft diet for the first few days –gradually return to a normal diet.
• refrain from tobacco and alcohol use for 1-2 weeks postoperatively.
• Provisional restorations should be checked and adjusted avoid impingement on surgical area.

• Stage 2 exposure surgery—
 Flap designs:
- Simple Circular “Punch” Incision: areas with sufficient zones of keratinized tissue
- Partial-thickness repositioned flap: usually if inadequate keratinized tissue is present
Objectives of Second-Stage Implant Surgery
1. To expose the submerged implant without damaging the surrounding
bone.
2. To control the thickness of the soft tissue surrounding the implant.
3. To preserve or create attached keratinized tissue around the implant.
4. To facilitate oral hygiene.
5. To ensure proper abutment seating.
6. to preserve soft-tissue aesthetics.

• Excess tissue over the cover screw is removed or displaced to visualise the outline of the cover screw
• A sharp blade is used to eliminate all tissues coronal to the cover screw removed
• The head of the implant is thoroughly cleaned of any soft or hard tissue overgrowth
• Healing abutments or standard abutments are placed on the implant.

• Immediate postoperative care—
• Reinforce good oral hygiene measures to patient around the implant.
• Chlorhexidine rinse to enhance oral hygiene for the initial 2 weeks while the tissues are healing.
• Avoid direct pressure to the soft tissue from dentures etc.—delays healing.
• Fabrication of the suprastructure can begin in about 2-4 weeks.

Maló P et al. Single-Tooth Rehabilitations Supported by Dental Implants Used in an Immediate-Provisionalization Protocol: Report on Long-Term Outcome with Retrospective Follow-Up, 2015
1-STAGE “Non-submerged” IMPLANT PLACEMENT
• A second intervention is not needed –implant is left exposed after the first surgery.
• Implants are left unloaded and undisturbed for a period similar to that for the
implants placed in the two-stage approach
• The implant or the healing abutment protrudes about 2 to 3 mm from the bone crest,
and the flaps are adapted around the implant/abutment.
• in posterior areas –the flap is thinned and sometimes sutured apically to periosteum
to increase the zone of keratinized attached gingiva around the implant.

• Flap Design, Incisions, and Elevation: always a crestal incision bisecting the existing keratinized tissue.
• Vertical incisions may be needed at one or both ends.
• Facial and lingual flaps in posterior areas should be carefully thinned before total reflection to minimize the soft tissue
thickness.
• not thinned in anterior or other esthetic areas of the mouth to prevent the metal collar from showing.
• Full-thickness flaps are elevated facially and lingually.
• Implant Site Preparation: identical to the 2-stage implant surgical approach. The primary difference is in the
placement of the healing abutment in relation to bone crest.
• Flap Closure and Suturing: edges of the flap are sutured with single interrupted sutures around the implant.
• Postoperative Care: similar to that for the 2-stage surgical approach except that the cover screw or healing abutment
is exposed to the oral cavity.
• avoid chewing in the area of the implant(s).
• Prosthetic appliances should not be used in the early healing period (first 4-8 weeks).
• Soft lining of denture is mandatory when a one stage, non-submerged surgical approach to implant placement is used.

ADVANCED IMPLANT SURGICAL PROCEDURES
 Localized ridge augmentation
 Management of extractions
 Maxillary sinus elevation and bone augmentation
 Recent advances
horizontal
vertical

Flap Management for Ridge Augmentation
1. Make incisions relative to placement of barrier membranes
2. Full thickness flap elevation at least 5 mm beyond the edge of the osseous defect
3. Minimize vertical incisions
4. Periosteal releasing incision– flap elasticity, tension-free closure
5. Avoid post-op trauma for ≤ 2 weeks
6. Wound closure: combination of mattress+interrupted sutures

HORIZONTAL BONE AUGMENTATION
• Dehiscence defects --managed during implant placement because most of the implant is covered and
stabilized by native bone.
• If the horizontal deficiency is large and the implant placement would result in significant exposure (i.e.,
implant body is significantly outside the alveolar bone), it may be better to reconstruct the bone before
implant placement (staged implant placement).
PARTICULATE BONE GRAFT
- Advantages:
- More rapid revascularization
- Larger osteoconduction surface
- More exposure of osteoinductive growth factors
- Easier biologic remodeling
- Disadvantages:
- Lack rigid scaffold—easily displaced
- Indications:
- in defects with multiple osseous walls that will contain the graft
- in dehiscence or fenestration defects when implants are placed during the bone augmentation procedure
MONOCORTICAL BLOCK GRAFT
- Source: intraoral or extraoral
- Fixed to recipient site with screws
- May be separated from overlying tissues with barrier
membrane or covered with mucoperiosteal flap
- Disadvantage: biologic limitation of revascularizing large
bone blocks.

VERTICAL BONE AUGMENTATION
• Most challenging
• Previous research—mostly unsuccessful: onlay block graft, particulate HA graft
• Recent approach: GBR
• Available evidence: limited

Distraction osteogenesis (Ilizarov, 1954)
• surgical technique developed to increase vertical bone height in the deficient jaw site
and
• Rationale : Under the proper circumstances, most cells in bone can differentiate into
osteogenic or chondrogenic cells needed for repair. (Ilizarov’s principle for deformity
correction)
• process of generating new bone by “stretching,” referred to as distraction osteogenesis.
• ADVANTAGE:
i. no second surgical site to harvest bone
ii. newly created bone has native bone at the crest-- withstand forces better than fully
regenerated bone.
• DISADVANTAGE:,
• unidirectional limitation of current devices– horizontal bone growth is difficult.
• High resorption—secondary grafting is required.
• broad use in the pre-prosthetic surgical indication with good predictability.

Simultaneous implant placement and GBR
• For implant placement in large alveolar bone defects
• Healing period of ≥ 6 months
• Modalities
• Use of barrier membranes
• Simple closure of flap
• Bone grafts
• Dahlin, 1991: membrane treatment was far superior with regard
to bone fill
• Palmer et al, 1994: better results in the membrane groups; four
of six sites treated with a membrane resulted in 95% to 100%
elimination of the dehiscence and total coverage of the threads.
In the control sites, only two of six sites showed moderate to
complete bone fill

MANAGEMENT OF EXTRACTIONS
- Quantity
- Quality
- Existing bone support
- Clinician’s judgement
- Patient’s preference
1. Immediate
2. Delayed
3. Staged

ITI Consensus 2003
• At the time of extraction
• Normal bone healing around
implant– enhanced BIC
• 2 mo. after extraction
• Allows time for soft tissue healing
• Reduces total length of treatment
• May cause more osteogenesis
• 4-6 mo. after extraction
• Resolution of infections
• Prevention of soft tissue
invasion
• Vascularization of bone graft

HISTORY
• Tatum, 1974– published by Boyne & James, 1980
• Modification of Caldwell-Luc technique
• Tatum’s modification, 1986: transalveolar sinus floor elevation via vertical tapping
• Summer’s modification, 1994: specific hollow osteotomes
Currently, well-accepted to increase bone volume in posterior maxilla.
Indicated in case of moderate increase in interocclusal dimension.

CONTRA-INDICATIONS
Local factors
- Tumor/ pathological growth in sinus
- Sinusitis
- Surgical scar/deformation of sinus cavity
- Periapical pathology in close proximity to sinus
- Severe allergic rhinitis
- Chronic topical steroid use
Systemic factors
- Radiation therapy
- Metabolic diseases (e.g., uncontrolled DM)
- Excessive tobacco use
- Drug/alcohol abuse
- Psychologic/mental impairment
INDICATIONS
- Alveolar bone height <10 mm
- Severely atrophic ridge and pneumatized
sinus
- Single tooth edentulous space with 5-7 mm
alveolar bone remaining

SURGICAL APPROACHES
1. Caldwell-Luc technique: superior lateral wall
2. Middle lateral wall opening
3. Inferior lateral wall opening
4. Crestal approach- through the alveolar crest superior to
sinus floor
1
2
3
4

• Pre-surgical evaluation of maxillary sinus
- Best seen with CT/ CBCT
- Evaluate for pathology, masses, presence/absence of septa
- investigation of lateral wall for intraosseous vascular channels—
avoid inadvertent bleeding due to surgical trauma.
- Simultaneous implant placement
- Implant stabilized with existing native bone– minimum 5 mm from
crest
- Inadequate remaining bone: subsequent surgery (6 months).

CRESTAL OSTEOTOMY TECHNIQUE- Indirect sinus lift
• Moderate bone height: 7-9 mm
• Indicated for limited sinus bone augmentation
• Osteotomes used to compress bone against sinus floor
• “controlled inward fracture” of sinus floor bone and membrane

CRESTAL OSTEOTOMY TECHNIQUE
• Complications & Considerations:
1. Acutely sloped sinus floor—may deflect osteotome
2. Repeated tapping—bothersome to patients with dense
cortex
3. Specific complication: Benign paroxysmal positional
vertigo (BPPV)
4. Osteotome alignment—mouth opening inadequate.
- Offset osteotomes

LATERAL WINDOW TECHNIQUE- Direct sinus lift

Comparison of sinus elevation procedures
Shenoy et al, 2020

RECENT ADVANCES
• COMPUTER-ASSISTED IMPLANT
SURGERY (CAIS)
 Precise.
3D CT Scan
data
Surgical
instrumentation
Identification
& registration
Sequence of steps for CAIS
1. DATAACQUISITION
2. IDENTIFICATION
3. REGISTRATION
4. NAVIGATION
5. ACCURACY
6. FEEDBACK

ADVANTAGES DISADVANTAGES
Improved accuracy and safety Initial cost of the system
Surgeon validation and expertise are maintained
Increased installation time for surgery
Security features can stop the rotary instrument in
proximity to important structures
Simulation can be visualized before surgery
Training time is mandatory
Implant position can be planned before surgery
Real-time information is provided to the surgeon
Accuracy depends on the various components of the
system
Inexperienced surgeons will improve their skill with
training
More challenging cases with greater comfort and
confidence
Inaccurate data from CT scan etc. can lead to difficulties in
registration
Surgical time is reduced using a surgical guide
Three anatomic or fiducial markers must be visible
Non-invasive surgery—with minimal or no flap reflection
COMPUTER-ASSISTED IMPLANT SURGERY (CAIS)

DENTAL IMPLANT MICROSURGERY
- Scope: enhanced soft tissue management and fine suturing,
drilling precision.
- Use of surgical microscope: immediate detection of subtle
changes in drill position—feedback corrections can be done
to handpiece.
- Drill’s angular position can be oriented relative to small
landmarks—implant platform surface level, angle of adjacent
cover screws.
- Allows optimal parallel positioning and depth of adjacent
implants.
- Implant drill angle can be accurately oriented to angulation
of root with 3-4mm of exposure (not visible otherwise
without microscope)
- Generally flapless—minimal patient morbidity

DENTAL IMPLANT MICROSURGERY
• Scope of operation:
Microsurgical tooth extraction:
Minimal trauma
Predictable aesthetics
Periotome luxation is preferred—limited injury to
papillae & preservation of gingival anatomy
No requirement of flaps—increased vision—
atraumatic technique.
Implant drilling
For maxillary anteriors—most favorable
bone is palatal: drill should follow.
Under microscope, visual feedback
constantly correct direction and angulation
of drill—avoid buccal placement
Optimal drilling speed—avoid frictional heat
to hamper osseointegration
Bone grafting
Socket may be filled with xenograft upto 1
mm of crest—to bridge jumping distance
E.g., filtered bone from osteotomy is rinsed
with 3% tetracycline solution & condensed
on top of xenograft. Covered with collagen
membrane.
Buccal gingival grafting
Recessions—anterior implants around buccal
marginal gingiva
Etiology: periodontal biotype, presence/absence
of buccal cortical plate. Surgical trauma, implant
position, emergence profile of final restoration
Solution: SCTG from palate into tunnel and
pouch on buccal aspect.
Immediate provisional restoration
Provides optimal esthetics + function
Minimizes tissue collapse—supports gingiva
Obturates surgical extraction socket—
particulate and soft tissue grafts
Immediate provisional fabrication
Immediate implant occlusion
Final implant restoration

HEALING FOLLOWING IMPLANT SURGERY

Peri-implant
soft
tissue
Immediate post-op: blood
clot between mucosa and
implant/bone surface.
24-48 h: Infiltrated by
PMN cells and replaced by
dense fibrin
Day 4: initial mucosal seal
Day 15: newly formed
connective tissue in
contact with implant.
Formation of JE between
mucosa and implant.
6-12 weeks: maturation of
peri-implant mucosa—
organized and aligned
collagen fibers to form
mature epithelial barrier.
Implant/peri-implant
mucosa
interface
Peri-implant mucosal
attachment to implant
surface is 3-4mm high.
Consists of JE (60%)
supported by underlying
CT (40%) coronal to bone.
External surface covered
by well-keratinized oral
epithelium—multicellular
layered to form retepegs.
5-15 layers of
basal+suprabasal cells
attached via desmosomes.
JE decreases in width, cells
flatten and align parallel to
long axis of implant.
Desquamation of most
coronal sulcular
epithelium—decreased
width of tissue collar.
Peri-implant
hard
tissue
(OSSEOINTEGRATION)
“Direct bone anchorage
to an implant body, which
can provide a foundation
to support a prosthesis.”
3 phases:
> Osteophyllic phase
> Osteoconductive phase
> Osteoadaptive phase
Berglundh et al, 2007 Schupbach & Glauser, 2007

POST-TREATMENT EVALUATION &
MANAGEMENT

Post-operative surgical evaluation checklist (modified from WHO checklist of surgical safety)
Factors to consider in periodic recall
appointments after dental implants:
1. Clinical examination
2. Peri-implant probing
3. Microbial testing
4. Stability
5. Radiographic examination
6. Oral hygiene and implant site maintenance

CONCLUSION
• The bone-to-implant interface plays an important role in biomechanics of the coping time
for healing and loading of dental implants.
• The soft tissue-to-implant interfaces are also important to maintain long-term
maintenance of stable marginal osseous level around implants.
• Clinicians must familiarize themselves with the underlying cellular and biomechanical
events to evaluate the success of implant, including surgical placement, restoration and
maintenance.
• It is essential to understand and follow basic guidelines to predictably achieve
osseointegration—which apply to all implant systems.
• In cases of inadequate bone support, careful diagnostics and treatment planning must be
done to reconstruct ridge deficiencies in order to place an implant.
• Future directions point towards the use of a microsurgical approach in these surgeries,
which helps advance dental implants from traumatic tooth extraction towards seamless
immediate replacement using such refined and digitally supported treatment modalities.

REFERENCES
• CARRANZA’S Clinical Periodontology, 10th Edition
• CARRANZA’S Clinical Periodontology, 13th Edition
• MISCH’S Contemporary Implant Dentistry, 1st Edition
• PALMER’S Implants in Clinical Dentistry, 2nd Edition
• Albrektsson et al., Biological aspects of implant dentistry:
osseointegration, Perio 2000, 1994

Dental Implants- part I and II: Biological and surgical aspects

Dental Implants- part I and II: Biological and surgical aspects

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