DENTAL IMPLANTS – BASICS , CLASSIFICATION, TIMING, CASE SELECTION

Presented byCathrine Diana PG II

• INTRODUCTION

genera of implants

• Terminologies

• Classification

• Implants

• Bone

• Bone – implant interface- theories

• Case selection and treatment planning

• Surgical procedure

• Complications

• Conclusion

Introduction

• Dental Implant:- “A graft or insert set firmly or deeply into or onto the alveolar process that may be prepared for its insertion

GENERA OF IMPLANTS

• A thousand years earlier, Egyptians nailed

copper studs with seashells carvings that

looked like teeth

• In 1913, one of the first implant systems was

introduced by Greenfield in Boston.

• In 1939, also in Boston, Strock made solid

vitallium screws in root forms for dental

implants.

• in 1943 in Germany, Dahl developed his

button inserts, which are also known as

intramucosal Implants

• Goldberg and Gershkoff published

their findings regarding subperiosteal

implants in 1946.

• Success rates for subperiosteal

implants are around 90% at five years,

65% at 10 years.

• Possible risk factors are

• bone resorption,

• paresthesia,

• fracture of the mandible, and

• soft tissue problems

• The same year, Sollier and Chercheve reported

the vertical transfixation implant, or staple

implant.

• This implant is tapped from under the anterior

mandible and has three, four, five or seven pins

protruding into the mouth.

• In 1969, Linkow designed his blade implant

system.

• The system is still used

today very rarely

• Roberts, who introduced the ramus

implant idea in 1970.

• The ramus implant is inserted into three

locations, the ramus right and left sides

and the anterior mandible

• modern endosseous dental implants and

the titanium alloy

that Osseo integrates with bone and forms a

strong firm bond by Per-Ingvar Brånemark, a

Swedish medical professor, in 1951

TERMINOLOGIES

– IMPLANT COMPONENTS

– Crest module

– Body

– Apex region

• Abutment:- “it is the portion of the

implant, supports or retains

prosthesis or implant

superstructure (metal framework

that attaches to the implant

abutment and provide retention

for removable or fixed prostheses)

• Cement retention

• Screw retention

• To retain removable prostheses

Prosthetic component:

– Healing screw/PME Impression coping

Lab analog

• Immediate loading: • Implant placement with primary stability and prosthetic

loading with a provisional prosthetic tooth at the same clinical visit or With in 2 wks

• Early loading: • Implants placed with primary stability and loaded with a

provisional prosthesis at a subsequent clinical visit .• should follow the onset of osteogenesis since bone formation

is enhanced by mechanical stimulation. Therefore, early loading should occur only after approximately 3 weeks of healing

Conventional loading • Implant placement (typically achieving primary stability) and

healing for 3 to 6 months in a submerged or non-submerged mucosal orientation.

• This time frame reflects the requirement for osteogenesis and woven bone remodelling to load-bearing lamellar bone and acknowledges the original recommendations of Brånemark .

Classifications

• 1 )Depending on anatomic site:

• Subperiosteal • Transosteal • Ramus frame

• Mucosal inserts / subdermal / Intramucosal

• Endosseous

• Endodontic

• 2) Depending upon surgical procedure

• Single stage surgery procedure• Two stage surgery procedure• Direct single stage

• 3) Depending upon histological features

• Fibro-osseous integration• Osseo integration

• Depending upon shape• Screws Cylinder screw

• Bullet shaped• Basket

Plates / blades• Root form

• 5 )Depending upon material used:• Bioactive

• Ceramics Hydroxyappetite

• Bioinert • Titanium carbon

Surface modifications of implant materials

• Passivation• Ion implantation• Surface texturing

The implant- bone interface

• There are two basic theories regarding the bone-implant interface.

a)Fibro-osseous integrationb) OsseointegrationGreek osteon, bone, and the Latin integrare, to make whole.

• To obtain a successful osseointegration Branemark and coworkers

proposed numerous factors.

• According to the proponents the oxide layer should not be contaminated

or else inflammatory reaction follows resulting in granulation tissue

formation.

• The temperature during drilling should be controlled by copious irrigation,

if not can inhibit alkaline calcium synthesis there by preventing

osseointegration.

• The first month after fixture insertion is the critical time period for

initial healing period. When loads are applied to the fixture during this

period primary fixation is destroyed.

Osseointegration Vs bio integration

• Meffert et al, (1987) redefined and subdivided the term

osseointegration into “adaptive osseointegration” and

“biointegration”.

• “Adaptive osseointegration” has osseous tissue approximating

the surface of implant without apparent soft tissue interface at

the light microscopic level.

• “Biointegration” is a direct biochemical bone surface

attachment confirmed at the electron microscopic level.

• Dr.charles Weiss, stated that the collagen fibers invest the implant,

originating at the trabeculae of cancellous bone on one side, weaving

around the implant, and reinserting into a trabeculae on the other side

• However, there was no real evidence to suggest that these fibers

functioned in the mode of periodontal ligament.

• the forces applied resulted in widening fibrous encapsulation,

inflammatory reactions, and gradual bone resorption there by leading to

failure.

Factors influencing the BIC

• Implant biocompatibility• Implant surface/dimension• Implant bed• Loading condition• Primary implant stability• implant length and diameter. • Surgical technique• Bone quality and quantity

• Implant biocompatibility• Materials used are:• Cp titanium (commercially pure titanium)• Titanium alloy (titanium-6aluminum-4vanadium)• Zirconium• Hydroxyapatite (HA), one type of calcium phosphate ceramic

material

• Implant surface

• Pitch, the number of threads per unit length, is an

important factor in implant osseointegration.

• Increased pitch and increased depth between

individual threads allows for improved contact area

between bone and implant.

• Moderately rough surfaces with 1.5µm also, improved

contact area between bone and implant surface.

• Reactive implant surface by anodizing (Oxide layer),

acid etching or HA coating enhanced osseointegration

• Implant bed

• Primary implant stability• micromotion of less than 30 μm – no effect on osteointegration• adequate‟ insertion torque • the additional torque used to secure or evaluate fixation of an implant in

bone (30-35Nw)• But may actually result in pressure necrosis and/or increase the strain

magnitude at the interface and therefore increase the amount of damage.

• implant length - > length better success rate• less than 10 mm – 50% failure

Schnitman, Wohrle, Rubenstein, DaSilva, & Wang, 1997).

• Surgical technique:

• 47°C at less than 1 minute to avoid overheating the bone The Heat generated is related to• The presence and temperature of irrigation• Amount of bone being prepared• Drill sharpness and design• Time of preparation• Depth of the osteotomy• Pressure on the drill• Drill speed• Variation in cortical thickness.

• Drill speed

• The speed of drills may be adjusted in relation to the quality of the bone

being prepared.

• D3 – 800 rpm

• D1- 2500 rpm proceed without exerting excessive pressure .

• Time of preparation

• pause approximately every 5 to 10 seconds.

• Pressure on the drill

• The average force placed on a hand piece during preparation of an osteotomy is 1.

2Kg. Enough pressure should be used to proceed at least 1 mm every 5 seconds

• Lavelle has demonstrated lower drilling temperatures in cortical bone with

internally cooled drills.

• The zone of non-vital bone formed after surgical trauma has been

observed to be progressively remodelled and substituted by vital,

functional bone after 6 months, with peaks of activity in the very early

stages after implant placement .

• mechanical trauma that may cause micro-fracture of bone during implant

placement.

• Mechanical trauma can lead to osteonecrosis and possible fibrous and

granulation tissue encapsulation around the implant instead of Osseo

integration.

• Bone quality and quantity: The modulus of density and elasticity of bone

is an indicator of its quality and quantity. The less dense the bone, the

lower the modulus and the less amount of bone–implant contact

• These factors are critically important in relation to the success or failure of

osseointegration

• Based on the above, there is a general agreement among clinicians that

the mandibular interforaminal area contains the best quality bone

• (Misch, 1990; Misch, Qu, & Bidez, 1999).

BONE CLASSIFICATION SCHEMES RELATED TO IMPLANT DENTISTRY

DIVISIONS OF AVAILABLE BONE

• Division A (Abundant Bone)

• >10-13mm height

• >5mm width

• >7mm mesio-distal length

• <30 degrees angulation

• C/I ratio <1

• Division A is most often restored with Division A root form implant.

• Division B (Barely sufficient bone)• 2.5-5mm width• >10-13mm height• >12mm mesio-distal length • <20o angulation between implant body and occlusal plane• Crown/Implant ratio <1• As the bone resorbs, the width of available bone first decreases at the

expense of the facial cortical plate. There is 25% decrease in bone width the first year, and 40% decrease in bone width within the first 1 to 3 years after tooth extraction. Once this Division B bone volume is reached, it may remain for more than 20 years.

• Treatment options • Modify by osteoplasty to permit the placement of root form implants 4 mm or

greater in width.• Insert a narrow Division B root form implant.• Modify the existing Division B bone into Division A by augmentation.

• Division C (Compromised Bone)• Unfavorable in: Width (C-w)• Height (C-h) • Angulation (C-a)• >30 degrees• C/I ratio >1• Treatment options :(1) Osteoplasty(2) Root form implants(3) Subperiosteal implants(4) Augmentation procedures(5) Ramus frame implants(6) Transosteal implants

Division D (Deficient Bone)• Severe atrophy• Basal bone loss• Flat maxilla• Pencil thin mandible• Treatment options : • most difficult to treat in implant dentistry. • Autogenous bone grafts to upgrade the division are strongly

recommended before any implant treatment is attempted. • Once autogenous grafts are in place and allowed to heal for 5 or more

months, endosteal or subperiosteal implants may be inserted, depending on the division of bone obtained.

• Linkow’s classification of bone density (1970)

• Class 1 -this ideal bone type consists of evenly spaced trabeculae with

small cancellated spaces.

• Class 2 - the bone has slightly larger cancellated spaces with less

uniformity of the osseous pattern.

• Class 3 -large marrow filled spaces exist between bone trabeculae

• Lekholm and Zarb (1985)

• Quality 1 ; composed of homogeneous compact bone

• Quality 2 : thick layer of compact bone surrounding a core of dense

trabecular bone

• Quality 3 : thin layer of cortical bone surrounding dense trabecular bone

of favorable strength

• Quality 4 : thin layer of cortical bone surrounding a core of low density

trabecular bone

• MISCH’S CLASSIFICATION (based on bone density)• D1: dense cortical bone• D2: thick dense to porous cortical bone on the crest and coarse

trabecular bone within.• D3: thin porous cortical bone on crest and fine trabecular bone within.• D4: fine trabecular bone• D5: immature, non-mineralized bone.• D1: > 1250 HU; D2: 850 to 1250 HU; D3: 350 to 850 HU; D4: 150 to 350

HU; and D5: < 150 HU.

Type advantage disadvantage

D1Anterior mandible, 5 months healing time

dense lamellar bone with complete haversian systemsLess stresses -near crestMore BIC

fewer blood vessels slower rate of 0.6 um /daymore difficult to prepare Bone is easily overheated

D2-anterior mandible, followed by the posterior mandible. Occasionally ant .maxillabone healing within 4 month

bone provides excellent BICintrabony blood supply – reduce overheatingImprove primary stability due to apical engage

Stress - around the crest greater magnitude

D3- ant- maxilla post.either archTPS/HAMaximum use of bone widthMay need sinus grafting,additional implant

Minimal osteotomyGood blood supply

the stripping of the thin facial plates during the osteotomyMore delecate to manageless than 1500 rpm <50% BIC6month healing

D4-posterior maxilla Need bone graftingMaximum use of bone length

little or no cortical crestal bone<25% BICto 8 months of undisturbed healing

Indications

• Patients with partially and fully edentulous arches.

• Patients with maxillofacial deformities.

• Patients who are unable to wear removable

dentures and have adequate bone for the

placement of implant.

• Good general health.

• Good oral hygiene & patient motivation.

• Patient should be emotionally stable, cooperative

and willing to keep the appointments required for

completion of treatment and maintenance

Contra-indications

• Uncontrolled or controlled diabetes/ medically compromised

• Chronic steroid therapy.

• High dose irradiation

• Smoking and alcohol abuse

• Pathologic conditions of the hard and soft tissues

• Presence of untreated or unsuccessfully treated periodontal diseases.

Preoperative diagnosis

• Clinical examination of the jawbone consists of palpation and

probing through the soft tissue (intra oral bone mapping) to

assess the thickness of the soft tissue at the proposed surgical

site.

Diagnostic imaging and technology• Types of imaging modalities:• Periapical radiograph• Occlusal • OPG• Cephalometric• CT – 3 dimentional• CBCT

• Phase 1:• Pre surgical imaging:• Identify disease• Determine bone quality and quantity• Determine implant position and orientation• • Phase 2:• Surgical and intra operative imaging:• Focused on assisting in surgical and prosthetic intervention in pt• Phase 3:• Post prosthetic implant imaging – • to evaluate long term maintenance of implant and function

Dental implant site preservation and development

• Alveolar ridge reconstruction with preprosthetic surgery

• Alveolar bone preservation following tooth extraction (immediate

implants, GBR, osseous grafting etc)

• Sinus lift/ grafting procedures

• Alveolar ridge augmentation using membranes

• Implant site development using ridge splitting technique

• Alveolar ridge development using distraction osteogenesis

• Growth factors in implant site development

Treatment planning1 .prosthesis design2. patient force factors3. Bone density/availability in edentulous site4 .Key implant position and number5 .Implant size6.Implant design

• prosthesis design-, implant supported denture over denture or fix

denture.

• patient force factors par functional habits- bruxism , clenching,

masticatory dynamic, crown height, opposing arch

• the force applied to the restoration differs by magnitude , duration type

and pre disposing factor

may need 1) additional implants that are wider in diameter

2)proper incisal guidance

3) narrow posterior occlusal table

4) enameloplasty of opposite natural teeth.

• Crown height space- should be between 8-12mm when not in range-

1) shorten cantilever length

2 )Increase number and diameter of implant and splint them

3) Fabricate removable restoration that incorporate soft tissue support

Remove them at night

• Bone density- softer bone Increase number and diameter of implant with

more and deeper threads. As more stress over crest so implant diameter is

more significant then length.

• minimum bone height for initial fixation and loading in D1=7mm,

D2=9mm,D3=12mm, D4->12mmm

Key implant position and number• General guidance to determine key implant positions-• No cantilever• No three adjacent pontics• Canine molar rule• Arch dynamics• Ideal one implant should replace one tooth and in edentulous implant

they should splint together.

Implant size

• Should be 1.5 mm from adjacent teeth

• Should be 3 mm from adjacent implant

• Should be 2 mm from adjacent anatomical

barrier

• Usually for mand. Incisors and max. LI=3-

3.5mm, for max. anterior and PM of both

arch and mand. Canine =4 mm. for all

molars =5-6mm

Implant position

• Ideally, occlusal forces should be

directed along the long axis of the

implants. Therefore ,The angle of the

osseous ridge crest is a key determinant

of implant angulation

• Maxilla anterior – 12 degree

• Mandible premolar - 10-15 degree

• Molar – 20-25 degree

Surgical procedure

• Implant site evaluation:• Minimum bucco –lingual width –

7mm• Mesio –distal 6.5mm• Height – 11mm• Soft tissue reflection – mid crestal

incision with a margin of 1.5mm keratinized tissue buccally extending to the sulcus of adjacent teeth

• Implant osteotomy:

• Start with 2mm end cutting drill at the center of crest

with 2500 rpm and copious irrrigtion upto 7-9mm

• Assess for proper position ,If incorrect position then

side cutting drill is used to stretch the osteotomy site.

• IOPA ensure the proper position with measuring tool

• Osteotomy proceeds with increasing size of twist drill

bit shorter than the size of desired implant

• Final implant position should clear the adjacent tooth

and the outer crestal cortical plate by 1.5mm

• Implant placement:• After final osteotomy, the site is lavaged and aspirated to

remove debris and blood• The implant is rotated with 30rpm (not more than 35 rpm) by

low speed high torque hand piece /hand ratchet• The implant should inserted slightly above (one stage) or

below (Two stage). It should be rigid with no mobility on slight compression

• Post insertion radiograph should be made to evaluate the

position , adjacent vital structure, crest module position. Any

correction can be made at this time. Low profile cover screw

is inserted into the implant body. Flaps most often

approximated with 4-0 PGA material

• If implant position is not with in the range of ideal , it may be

removed and reinserted after several months later in most

ideal position

Implant maintenance• The principle of this method is to detect peri implant infections as early as

possible and to intercept the problems with appropriate therapy.• The basis for this system is a regular recall of the implant patient and the

repeated assessment of the following key parameters around each implant.

• The presence of plaque• The bleeding tendency of the peri implant tissues • Suppuration• Presence of peri implant pockets• Radiological evidence of bone loss.• Optimally an implant should yield negative results for all these

parameters. In this case no therapy is needed and one may consider increasing the length of recall interval.

• If plaque and /or an increased tendency to bleed are detected, then the

implants are mechanically cleaned using a rubber cup and polishing paste.

Instruments made of softer material than titanium may be used to remove

hard deposits. Oral hygiene practices should be checked, and the proper

plaque control technique should be instructed and reinforced (A)

• In the presence of pus or if first signs of peri-implant tissue destruction are

detected (pockets 4-5 mm & slight bone loss) regimen A is combined with

application of a local antiseptic (B). The periimplant pockets are irrigated

with 0.2% Chlorhexidene and the patient is advised to rinse twice daily

with 0.12% Chlorhexidene.

• If pocket depth > 5mm, radiograph is taken. If there is clear evidence of

bone loss, then a microbiological sample is taken. Evidence of anaerobic

flora, treatment A+B and in addition systemic antimicrobial therapy (c)

• If the bone destruction has advanced considerably, surgical intervention to

correct the tissue morphology on to apply GBR techniques may be

necessary (D).

• The goal of this cumulative treatment approach is to intercept peri

implant tissue destruction as early as possible and to avoid explanation

due to loss of osseointegration

Complications• Inferior alveolar nerve injury is a serious complication with incidence

ranged from 0 to 40% .As a result, many important functions such as speech, eating, kissing, make-up application, shaving and drinking were affected. This influences patient’s quality of life and often resulted in negative psychological adverse effects. The most common causes of iatrogenic inferior alveolar nerve injuries are discrepancies of radiographs, surgeon’s mistakes, low resistance of mandibular spongy bone and lack of mandibular canal superior wall

• Incision line opening :• Minor opening - proper oral hygiene practice with chlorohexidine rise –

wait for granulation of tissue• If no granulation occur > 2wks – trim the margins - minor bleeding -

followed by granulation• Implant exposure:

• Partial exposure –• Remove cover screw- flush with chlorohexidine –insertion of permucosal

extention – hygiene maintenance• Complete exposure• Aggressive therapy – removal of cover screw- flush with chlorohexidine-

assess the bone level-reflect the soft tissue- curettage of granulation tissue –implant surface cleaned wit citric acid/baking soda- followed by bone grafting and membrane coverage

• Implant failure:• Mobility of implant during healing period • Pain , infection• Radiolucency around implant whatever the cause, the implant should be

removed. Grafting and reinsertion can be done after 8-10wks.

Conclusion

• Dental implants have overall had high success rates, but their placement and restoration still have the boundaries of both biomedical science and art.

• The effectiveness of different designs of implant-supported prostheses as well as associated treatment modalities, prostheses retention and stability, leads to improvement in speech, function and quality of life trials

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Binon IJOMI 2000, Vol 15 No.1. 5. Current status of dental implants. A periodontal perspective.

Perry Kokkevold. IJOMI 2000 vol. 15(1)6. Bone implant interface around titanium implants under different

loading condition. Romanos JP 2003 OCT 74 (10). 7. Longevity of dental implants in type IV bone: a systematic review

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