DILIP KUMAR SINGH

GUIDE–PROF(DR.)SAIBAL KUMAR SEN DEPARTMENT OF PROSTHODONTICSGNIDSR

Anatomy of gingiva & periodontium

-prosthodontic significance

Contents

1. Introduction to periodontium2. Different elements of periodontium3. Occlusal forces & periodontium4. Concept of BIOLOGICAL WIDTH5. Pathologies of periodontium6. Prosthodontic importance of periodontiuma. RPD and periodontiumb. FPD and periodontiumc. Implant and periodontium7. Conclusion8. References

Introduction

Periodontium is an indispensible part of any Prosthodontic treatment- RPD, FPD, Implant, …… It serves as the

foundation on which any prosthodontic treatment stands on .

Periodontium

Gingiva Periodontal

ligament Cementum Alveolar process

The Gingiva

The Gingiva is the part of the oral mucosa that covers the alveolar processes of the jaws and surrounds the necks of the teeth.

Mainly of three types Marginal Attached Interdental

COL

PAPILLAJUNCTIONAL EPITHELIUMFREE GINGIVAATTACHED GINGIVAMUCOGINGIVAL JUNCTIONALVEOLAR MUCOSA

CEMENTUMPERIODONTAL LIGAMENTALVEOLAR BONE/CRIBIFORM PLATELINGUAL PLATETRABECULAR/CANCELOUS BONE

Marginal/margin/free/unattached gingiva

Attached Gingiva

Extends from base of the pocket to the mucogingival junction

The width of attached & keratinized Gingiva is often narrower in periodontal diseases

Gingiva:Interdentalpapilla

Lang,N.P, and loe,H :the relationship between the width of keratinized gingiva & gingival health. J. periodontal 43:623-627, 1979

2mm of keratinized Gingiva , including 1mm of attached Gingiva , is adequate to maintain gingival health

Wilson,R.D & Maynard, J.G:the relationship of restorative dentistry to periodontic.J.periodontal 1979

5mm of keratinized Gingiva (2mm of free Gingiva +3mm of attached Gingiva) is essentials for placing sub gingival margins

Gingival Fibres

The gingival fibres are arranged in three group-GingivodentalCirculartransseptal Functions: To brace the marginal gingiva firmly against

the tooth. To provide the rigidity necessary to withstand

the forces of mastication without being deflected away from the tooth surface.

To unite the free marginal Gingiva with the Cementum of the root and the adjacent attached Gingiva.

Color

The colour of the attached and marginal gingiva is generally described as "coral pink" and is produced by

the vascular supply, the thickness and degree of keratinisation of the

epithelium, and the presence of pigment-containing cells.

The alveolar mucosa is red, smooth, and shiny rather than pink and stippled.

The epithelium of the alveolar mucosa is thinner, is non keratinized, and contains no rete pegs

The connective tissue of the alveolar mucosa is loosely arranged, and the blood vessels are more numerous

Size

The size of the gingiva corresponds with the sum total of the bulk of cellular and intercellular elements and their vascular supply. Alteration in size is a common feature of gingival disease

Contour The contour or shape of the gingiva varies

considerably and depends on the shape of the teeth their alignment in the arch, the location and size of the area of proximal contact

The marginal gingiva envelops the teeth in collar like fashion and follows a scalloped outline on the facial and lingual surfaces.

It forms a straight line along teeth with relatively flat surfaces. On teeth with pronounced mesiodistal convexity (e.g., maxillary canines) or teeth in labial version, the normal arcuate contour is accentuated, and the gingiva is located farther apically

Consistency

The gingiva is firm and resilient and, with the exception of the movable free margin, tightly bound to the underlying bone.

The collagenous nature of the lamina propria and its contiguity with the mucoperiosteum of the alveolar bone determine the firmness of the attached gingiva.

The gingival fibres contribute to the firmness of the gingival margin

Position

The position of the gingiva refers to the level at which the gingival margin is attached to the tooth.

When the tooth erupts into the oral cavity, the margin and sulcus are at the tip of the crown; as eruption progresses, they are seen closer to the root.

During this eruption process, the junctional epithelium, oral epithelium, and reduced enamel epithelium undergo extensive alterations and remodeling

The distance between the apical end of the junctional epithelium and the crest of the alveolus remains constant throughout continuous tooth eruption (1.07 mm).

Periodontal ligament

The periodontal ligament is the connective tissue that surrounds the root and connects it with the bone. It is continuous with the connective tissue of the gingiva and communicates with the marrow spaces through vascular channels in the bone.

The average width is about 0.2 mm

Principal fibres of the periodontal ligament

Primarily composed of bundles of type I collagen fibrils.

Classified into several groups on the basis of their anatomic location1. Alveolar crest fibres2. Horizontal fibres3. Oblique fibres4. Periapical fibres5. Interradicular fibres

Also contains oxytalan fibresAlso contains cell rests of

Malassez

Functions of the Periodontal Ligament

Physical FunctionFormative and Remodeling

FunctionNutritional and Sensory

Functions

Physical Functions

Provision of a soft tissue "casing" to protect the vessels and nerves from injury by mechanical forces

Transmission of occlusal forces to the bone.

Attachment of the teeth to the bone.Maintenance of the gingival tissues

in their proper relationship to the teeth.

Resistance to the impact of occlusal forces (shock absorption)

Change in PDL during mastication

According to Biancu et.al 1995 & kaneko et al 2001

Histologically , PDL adapts to occlusal load by thickening of PDL space at stress point whereas loss of occlusal function is manifested by narrowing of PDL space

According to Davies et al 2001PDL physiologically adapts to accumulated

occlusal loading by resorption of alveolar structures & resultant tooth mobility, which is actual occlusal trauma & is reversible if the occlusal load is reduced

Cementum

Cementum is the calcified mesenchymal tissue that forms the outer covering of the anatomic root

There are two main types of root cementum: acellular (primary) and cellular (secondary)

Both consist of a calcified interfibrillar matrix and collagen fibrils.

Ankylosis

Fusion of the cementum and alveolar bone

Resorption of the root and its gradual replacement by bone tissue

Implants

ALVEOLAR PROCESS

The alveolar process is the portion of the maxilla and mandible that forms and supports the tooth sockets

Consists of-Compact bone cortical bone alveolar bone proper (also known as

the cribriform plate or lamina dura) andCancellous bone

Alveolar process

1 Alveolar bonea) Cribiform plateb) Alveolar wallc) Lamina dura2 Trabecular bone3 Compact bone

Occlusal Forces and the Periodontium

Changes in Periodontium due to Occlusal Forces

Alveolar bone undergoes constant physiologic remodeling in response to occlusal forces.

When occlusal forces are increased, the cancellous bony trabeculae increase in number

and thickness, and bone may be added to the external surface of

the labial and lingual plates.

The periodontal ligament can accommodate increased function

with an increase in width, a thickening of its fiber bundles,

and an increase in diameter and number of Sharpey's fibers.

Forces that exceed the adaptive capacity of the periodontium produce injury called trauma

from occlusion.

When occlusal forces are reduced, the number and

thickness of the trabeculae are reduced. The periodontal ligament also atrophies,

appearing thinned, and the fibers are reduced in number and density, disoriented and

ultimately arranged parallel to the root surface

Concept of BIOLOGICAL WIDTH

Biological width is defined as the physiologic dimension of juncjtional epithelium and connective tissue attachment

It is approximately-2.04mm

(0.97mm-junctional epithelium +1.07-connective tissue)

For any Prosthodontic treatment to be successful the biologic width should be preserved

Clinical importance of biological width Placement of the restorative margin 0.5mm

into the sulcus allows for the maintenance of the biologic width

If the biologic width is not preserved ,it may result in

Gingival inflammation Pocket formation Loss of alveolar boneSo any interference to the biologic width

should be considered before planning any prosthesis

Greater than 3.0mm of soft tissue b/w the bone & gingival margin, with adequate attached gingiva allows crown lengthening by gingivectomy

With less than 3.0mm of soft tissue b/w the bone & gingival margin ,or less than adequate attached gingiva , a flap procedure & osseous recontouring are required for crown lengthening

In case of caries or fracture , at least 1.0mm of sound tooth structure should be provided above the gingival margin for proper restoration

Pathologies of periodontium

Gingival diseases-Gingivitis

Chronic periodontitis Aggressive

periodontitis Necrotizing

periodontal diseases NUG NUP Abscesses of

periodontium

Gingivitis

Most common gingival diseases

Its nothing but the inflammation of gingiva resulting in bleeding on slight probing

Mainly due to the local irritating factors-plaque but may be sometimes associated with non plaque induced factors

Gingivitis

NO PROSTHESIS can be placed in such an inflamed and swollen condition of gingiva because it not only affects the fit but also will irritate the tissue more , hence will aggravate the condition

Margins of the restoration cannot be placed properly

PERIODONTITIS

It is the inflammation of the supporting tissues of the teeth

It results in progressive destruction of PDL & Alveolar bone with pocket formation & gingival recession or both

Here clinical sign of attachment loss is seen

PERIODONTITIS

Periodontitis is directly associated with the support of ABUTMENT TEETH

It weakens the supporting structures of the teeth making them mobile & incapable to bear the occlussal load transmit the same to alveolar bone

Any pathology in periodontium

Inflammation of gingiva Loss of attachment Destruction of PDL

&Ultimately bone loss

Supporting structures of teeth are weakened

Abutment teeth fails to bear the required Occlusal load & transfer the same to the bone

Support for any prosthesis will be COMPROMISED

Eventually leads to TREATMENT FAILURE

RPD and PERIODONTIUM The ultimate success of RPD directly depends on

the health & integrity of supporting structures of the teeth esp those to be used as the ABUTMENT

following factor should be evaluated carefully before fabricating a RPD

Periodontal diseases

Degree of gingival recession

Loss of epithelial attachment

Furcation involment

Tooth mobility

Amount of bone loss to be assessed by radiograph

McGivney GP, Castleberry DJ ;McCracken’s RPD 8th ed

The above factors decide the status of abutment teeth &the remaining structures

Support for the prosthesis

Treatment outcome

Frechette A. Influence of partial denture design on distributionof forces on abutment teeth. J Prosthet Dent 1956;6:195–212

The forces occurring with the RPD can be widely distributed & directed & can be minimized by appropriate design of RPD

The design of RPD requires both mechanical & biological consideration

Rigid major connector & max coverage of the denture bearing areas with denture bases are of great importance in reducing stress on the abutment teeth

Chamrawy E. Qualitative changes in dental plaque formation related to removable partial dentures. J Oral Rehabil 1979;6:183–188

The use of RPDs leads to detrimental changes in the quality and quantity of plaque. Implementing meticulous hygiene of both the oral cavity and dentures can offset these changes.

Isidor F et al J. Periodontal 1990 ; 61 :21-26 Oral hygiene is considered to be one of the most imp factor

in RPD prothesis Maintenance of oral hygiene is more crucial for RPD than for

FPD

a/c to z lahaviz DK, celebric A, valentio peruzovic: Appropriate design & good oral hygiene may decrease the

incidence of periodontal disease

(Jour. Oral rehabit 2001)

Possible movements of partial denture

There are three possible movements –depending upon the differences in the support characteristics of the abutment teeth &the soft tissue covering the residual ridges

Rotation around the fulcrum line passing through the most posterior abutments when denture base moves vertically towards or away from the supporting residual ridges

Rotation around the longitudinal axis formed by the crest of residual ridge

Rotation around the vertical axis located near the centre of the arch

The 1st two movements do not occur in tooth supported partial dentures whereas the 3rd possible movement occurs in all partial dentures

Vertical vs horizontal forces More periodontal fibers

are activated to resist forces directed vertically on the tooth than are activated to resist horizontal forces

Therefore , stabilizing components against horizontal movements must be incorporated in any partial denture design

McGivney GP, Castleberry DJ ;McCracken’s RPD 8th ed

Design of RPD components & periodontium While designing RPD components also, the gingiva &

periodontium is taken care ofa/c to stewart & Rudd 1968 Broad distribution of stress through the use of rigid major &

minor connector, multiple rests or guiding plane helps in preservation of underlying periodontium

(jour of prosthodent 1968)

McHenry KR, Johansson OE, Christersson LA. The effect of removablepartial denture framework design on gingival inflammation:A clinical model. J Prosthet Dent 1992;68:799–80

Gingival areas that are covered by parts of RPD without relief shows more adverse reaction both clinically & Histologically whereas the uncovered areas are least affected

Increased tissue coverage by lateral major connector causes more plaque accumulation

Designing of RPD

The maxillary major connectors are placed 6.Omm away from the gingival margins It is called as INTENTIONAL RELIEF ,given to avoid any injury to the gingiva

Should be rigid enough to uniformly distribute the occlusal forces acting on any part of the prosthesis without undergoing distortion

Designing of RPD

Mandibular major connectors are placed 4 mm away from the marginal gingiva

Lingual bar should be tapered superiorly with a half pear shape in cross-section & should be relieved sufficiently

Lingual plate is used in case of periodontically weakened lower anterior teeth

Borders of major connectors should be parallel to the gingival contours

The metal framework should cross the gingival margins at an sharp angle of 90

the other components –minor connectors ,rests ,direct & indirect retainers etc are placed on the abutment teeth &hence directly depends on the periodontal support of the same for their proper functioning

Becher CM , Kaldahl W ( jour of prosthodent 1982)

Additional design should be considered viz stabilization of all compromised teeth, potential for addition of artificial teeth if natural teeth are lost & a minimum of soft tissue coverage spl those tissue at the gingival margin of the remaining teeth

Minor connector

Connecting link b/w major connector or denture base and other components of RPD

Function: Transfer forces acting

on the artificial teeth to the abutment teeth

Forces acting on the abutment teeth are also transferred uniformly throughout the prosthesis

Chou T-M, Caputo AA, Moore DJ, Xiao B. Photoelastic analysis and comparison of force-transmission characteristics of intracoronal attachments with clasp distal-extension removable partial dentures. J Prosthet Dent 1989;62:313–319.

Clasp retained designs produces less torque on abutment teeth than intra coronal design

RPI design produces lowest torquing forces on the abutment teeth

RPI Clasp Assembly Clasp assembly consists:

A mesioocclusal rest with the minor connector placed into the mesiolingual embrasure

A distal guiding plane, extending from the marginal ridge to the junction of the middle and gingival thirds of the abutment tooth, prepared to receive pp

The proximal plate, in conjunction with the minor connector supporting the rest, provides the stabilizing and reciprocal aspects of the clasp assembly.

The I-bar should be located in the gingival third of the buccal or labial surface of the abutment in 0.01inch undercut

Proximal plate minor connector Proximal plate minor

connector Width=1/2 distance b/w

tips of adj buccal & lingual cusps of the abutment tooth

Length=area of the abutment from marginal ridge to 2/3rd the length of enamel crown

Shape=triangular with apex located buccally & the base lingually

McCracken’s removable partial denture 11th edition

Guiding plane

Guiding plane-two or more parallel vertical surfaces of abutment teeth, so shaped to direct a prosthesis during placement and removal

More vertical walls that are made parallel , the fewer the possibilities that exist for dislodgement

If some degree of parallelism does not exist during placement & removal, trauma to the teeth & supporting structures & strain on the denture parts are inevitable

Guiding plane & design of Minor connector

There are three basic approaches to the application of RPI system

Guiding plane &corresponding proximal plate MC extends entire length of the proximal tooth surface . physiologic relief is required to prevent impingement of gingival tissue during function

This directs the functional forces in horizontal direction thus teeth are loaded more than edentulous ridge

Guiding plane & pp extends from marginal ridge to junction of middle & gingival thirds of the proximal tooth surface

This decrease in the contact area of pp on guiding plane more evenly distributes the functional forces b/w tooth & edentulous ridge

Here there is no contact b/w pp & prepared guide plane, resulting in uncontrolled stress to the abutment

McCracken’s removable partial denture 11th edition

Stress breaker

A device which relieves the abutment teeth of all or part of the occlusal forces

A type of hinge joint placed within the denture framework ,which allows two parts of the framework on either side of the joint to move freely

Soft tissue are more compressible than the abutment teeth

In tooth-tissue supported partial denture , when occlusal force is applied , the denture tends to rock due the difference in the compressibility of the abutment tooth & soft tissue .As the tissue are more compressible, the amount of stress acting on the abutment tooth is increased. This can have harmful effect on the abutment

To protect the abutment tooth from such condition , a stress breaker is incorporated in the denture

FPD & PERIODONTIUM

Success of FPD

Health of abutment teeth

Periodontal health of the teeth

Any pathology of periodontium will weaken the support of the abutment teeth , hence the prosthesis will be compromised

a/c johnson et al 1986,macguire & nunn 1996 & grossman & sadan 2005

A periodontally compromised tooth can be diagnosed from probing depth, mobility , supporting bone volume, crown to root ratio, root form , periodontal ligament area

Reduction in periodontal support

Worsens the prognosis of the tooth

Radiographic evaluation of periodontal bone loss greatly influences Prosthodontic decision making (moser et al 2002)

Abutment selection & periodontium

Abutment refers to a tooth or a part of tooth that supports FPD

It is the abutment tooth that takes the maximum Occlusal load which is then transmitted through the long axis to the basal bone

Selection of abutment is an important criteria for the designing of FPD

Abutment selection

The supporting tissues surrounding the abutment teeth must be healthy, free from inflammation before any prosthesis can be contemplated. Normally abutment teeth should not exhibit mobility, since they will be carrying an extra load. The roots & their supporting tissue should be evaluated for three factors:

crown root ratio root configuration periodontal ligament area

Crown root ratio

Measured as length of tooth Occlusal to the alveolar crest compared with length of root embedded in bone.

As the level of alveolar bone moves apically, the lever arm of that portion out of bone increases, and the chances of lateral forces is increased

The optimum crown root ratio is 2:3 . A ratio of 1:1 is the minimum ratio that is acceptable for a prospective abutment under normal circumstance

Root configuration

Important criteria to evaluate abutment tooth from periodontal point of view

Roots that are broader labiolingually than they are mesiodistally are preferable than that are round in cross-section

Multirooted posterior teeth with divergent roots will offer better periodontal support than the roots that converge , fuse or with conical configuration

Single rooted tooth with irregular pattern is preferred to one that is tapers uniformly

Periodontal ligament area

Another important factor in the evaluation of the abutment teeth is the root surface area or the area of periodontal attachment of the root to the bone

Larger teeth have a greater surface area and are better able to bear added stress

When supporting bone has been lost due to periodontal disease, the involved teeth have lessened capacity to serve as abutments.

ANTES LAW

JOHNSTON et al 1986 gives Antes law

According to it “sum of the pericemental area of the abutment teeth should be equal to or greater than the pericemental area of the teeth being replaced”

Pontic design & periodontium Pontic or artificial tooth is derived from the latin, pons

=bridge, it is not a simple replacement,b’coz placing an exact anatomic replica of the tooth in space would be hygienically unmanageable

Pontic-component of FPD that replaces a missing tooth & restores its function & appearance (GPT, 8th edition 2005)

Acc to parkinson &schaberg 1984 The design of pontic will be dictated by Esthetics Function Ease of cleansing Maintenance of healthy tissue on the edentulous ridge Patient’s comfort J.prosthet dent 1984;51:51-54

Design considerations

Acc to j.prosthet dent 1966;16:251-284Stein RS stated Extent & shape of the pontic contact

with the ridge is very important Excessive tissue contact-major factor in

the failure of FPD Should have minimum contact area b/w

pontic & the ridge The gingival surface of the pontic should

be convex

Tjan AH :biologic pontic design Gen Dent 1983 ;31:40-44

Pontic should not encroach on unattached mucosa or otherwise an ulcer will form

The tip must be restricted to keratinized gingiva

Acc to j prosthet dent 1966;16:937-947 The mesial, distal & lingual gingival embrasures

should be wide open to allow the easy access for cleaning

Contact b/w pontic &tissue must allow the passage of floss from one retainer to other

Types of pontic design

Ridge lap (saddle) Modified Ridge lap Hygienic or sanitary Conical ovate

Ovate pontic

Ovate pontic

Most esthetics Convex tissue surface

resides within the socket-gives perfect emergence profile

Not easy to clean Requires surgical process Modified ovate pontic Less convex-easy to

clean requires little or no surgery

Occlusal forces

Reducing the buccolingual width of the pontic by as much as 30%

has been suggested as a way to lessen occlusal forces, thus the

loading to abutment teeth.

Analysis reveals that This practice has little scientific basis.

Forces are lessened only when chewing food of uniform

consistency .

12% increase in chewing efficiency can be expected from a one-

third reduction of pontic width.

JPD1975,Vol33

Pre-treatment assessment

Loss of residual ridge

contour may lead to

unesthetic open

gingival embrasures

("black triangles")

food impaction and

percolation of saliva

during speech.

GINGIVAL ARCHITECTURE PRESERVATION

The concept of atraumatic extraction followed by

socket grafting and placement of an ovate pontic

to preserve gingival architecture was presented

by Schlar.

Ridge augmentation procedures can be more

invasive and less successful than the results

obtained by preserving the patient’s original ridge

and gingival contours.

The Journal of Contemporary Dental Practice,

Volume 5,, 2004

Gingival architecture preservation

Atraumatic extraction is done

interim FPD(ovate pontic) is prefabricated

PR is placed immediately inside socket(ovate pontic is being extended 2.5mm into the socket

blanching of Interdental papilla

restoration after 12 months

Interdental papilla is preserved

Finish linesPlacement of FINISH LINES of the

restoration is also guided by the contour &the position of gingiva

Depending on it finish lines can be

placed either supragingivally-least impact on

the periodontium equigingival –more plq accu sub-gingivally-most impact on

the periodontium

Ideally the margins of the restoration should be placed supragingivally if possible-LEAST IMPACT ON PERIODONTIUM

• INDICATIONS OF SUB GINGIVAL FINISH LINES• (JPD 1973;29:301-304 & JPD1982; 47:625-632)• Short clinical crowns• Sub gingival caries• Root sensitivity • Aesthetic purpose• Additional retention etc....

Acc to ReevesWG 1991 (JPD 1991;66:733-736)• Deeper the restoration margin resides in the gingival sulcus ,

greater is the inflammatory responses• Sub gingival finish lines usually results in PERIODONTITISAcc to IngberJS ,RoseLF 1977 Finish lines placed at a distance of less than 2.0mm can cause• Gingival inflammation• Pocket formation • Loss of alveolar bone(The biologic width-a concept in periodontics and restorative

dentistryAlpha omegan 1977; 10:62-65 )

FURCATION INVOLVEMENT

Glickman I: clinical periodontology, ed 2 , philadelphia, 1958, W.B.Saunders co..,pp694-696

Classified furcation in 4 grades

Normal Furcation No bone or attachment

loss No flute detected on

clinical probing

Grade I involvement

Incipient lesion Supra bony pocket Flute concavity

detected on probing

Slight bone loss in Furcation area

Radiograph changes unusual

Grade II involvement Lesion is cul-de-sac Bone is destroyed on

one or more aspect of Furcation but a portion of the alveolar bone and PDL remains intact

Clinically gingival recession may be present but the Furcation entrance is not visible

Grade III involvement

Interradicular bone is completely absent horizontally

Lesion is through and through

Furcation entrance is still not visible and is occluded by the gingival tissue

Grade IV furcation Loss of attachment

within the furca through one entrance to the other, with apical gingival recession

Clinically visible

Depending on Class of Furcation involvement Extent configuration of bone loss Other anatomic factors There can be two therapeutic

approaches Non-surgical-(for grade I &II cases) Maintaining oral hygiene Scaling & root planning Odontoplasty & osteoplasty

surgical –(late grade II , III & IV)

Root resection –surgical removal of all or portion of the root

Hemi section-surgical separation of a multi-rooted tooth through Furcation area such that root or roots ,may be surgically removed along with the associated crown portion

Crown modification

Implant & periodontium Implant –a substance that is

placed in the jaw to support a crown or a FPD or RPD

INDICATION- Completely edentulous pt

with excessive ridge resorption

Partially edentulous teeth where RPD will weaken the abutment teeth & provides reduced masticatory efficencey

Single tooth replacement where FPD cannot be placed

Patients desire

mechanism

When an implant is first placed in the bone there should be a close fit to ensure stability.

The space between implant and bone is initially filled with a blood clot and serum/bone proteins.

the initial response to the surgical trauma is resorption, which is then followed by bone deposition

The stability of the implant at the time of placement is very important and is dependent upon bone quantity and quality

Following the loss of a tooth, the alveolar bone resorbs in width and height

Classification of implant

Based on the placement of implants within the tissue

Epiosteal-it is placed on the surface Endosteal-placed within the basal boneTransosteal-penetrates both the cortical

plates

osseointegration

Proposed by P.I Branemark in 1982 Implants integrate with the bone

such that the bone is laid very close to the implant material without intervening connective tissue

Stated that implant should not be loaded & must be kept out of function during the healing period for osseous integration

Commonly used-commercially pure Ti (CPTi)

Early loading: High initial load on an implant

immediately following placement results in the formation of fibrous capsule rather than OI

Late loading:Excessive mechanical load on an OI

implant can result in the breakdown of the interface with resultant implant failure & therefore overload should be avoided

Fibro-osseous integration

Proposed by Weiss in 1985 Stated that a fibro-osseous ligament is

formed b/w the implant & the bone & this ligament is considered as the peri-implant ligament found in the gomphosis

He defends the presence of collagen fibres at bone-implant interfacehe advocates the early loading of the implant

Importance of bone quality & quantity –implant prosthesis

Both quality & quantity influences osseointegration & hence success of implants

Many attempts have been made to classify different bone densities to aid surgeons in selecting appropriate implants, surgical technique/procedure, and predict future success rates

Lekholm and Zarb(1985) classified bone quality into four categories

Type I bone -homogenous compact bone Type II bone -a core of dense trabecular bone with

a thick layer of compact bone surrounding it

Type III bone -a thin layer of cortical bone surrounding dense trabecular bone of favourable strength

Type IV bone - a thin layer of cortical bone surrounding a core of low-density trabecular bone

It is recommended that acid-etched titanium implants be used on Type I, TPS implants in Type II and Type III bone, and Type IV bone receive HA-coated implants

Espositpo M et al. Biological factors contributing to failure of osseointegrated oral implants: Eur J Oral Sci. 1998;106: 721-764

Scortecci G, Misch C, Benner K. Implants and RestorativeDentistry. London:Martin Dunitz Ltd. 2001. pg59-87

Bone quantity: The available bone at edentulous & future implant site

Volume of available bone is evaluated byBone heightBone widthBone lengthBone angulationCrown implant ratio

Requirement for the ideal placement of implant:Minimum bone height-10mmMinimum bone width-5mmMinimum bone length-7mm

Transmucosal abutment (TMA) used to link the implant body to the

prosthesis Also know as implant abutment basically of four types: cylindrical,

shouldered, angled and customizable Made up of CPTi cylindrical designs :are employed where themucosal aspect of the prosthesis is to be

placed some distance above the oral mucosa to aid cleaning, the so-called 'oil rig' design.

Shouldered designs: permit the prosthesis to finish at or below the 'gingival margins', providing a more natural-appearing emergence profile for the superstructure.

Healing abutment

temporary implant-connecting part placed on the implant body to create a channel through

the mucosa while the adjacent soft tissues heal.

normally wider than the corresponding regular abutment to compensate for some tissue collapse into the space when placing the regular abutment

They also allow for a period of resolution of tissue swelling before selecting the final abutment so as to ensure its optimum height

Recent advancements

Gingival prosthesis

I. Gingivl resessionII. Gingival

prosthesisIII. Periodontal acrylic

veeners

Gingival porcelain

Dental esthetics is based not only on the “white component “ of the restoration but also on the “pink component”.

Gingival pink colored prosthesis are used to replace missing gingival tissues.

Materials: Pink autocure acrylics.

Heat cure acrylics. porcelain

Conclusion

So we have seen how & why the knowledge of a periodontium is important for a prosthodontist

Knowing the basic anatomy of gingiva & periodontium helps a prosthodontist to correlate the available conditions in the pts mouth & to classify the same as normal & abnormal which eventually helps the dentist in better diagnosis & treatment planning the related problem

Referances

Carranza’s clinical periodontolgy,10th edition

mcCracken’s removable partial prosthodntics,11th edition

Shillingburg, fundamentals of fixed prosthodontics 3rd edition

Biancu S, Ericsson I, Lindhe J (1995). Periodontal ligament tissue reactions to trauma and gingival inflammation. An experimental study in the beagle dog. J Clin Periodontol 22:772–779.

Biewener AA (1993). Safety factors in bone strength. Calcif Tissue Int 53(Suppl 1):S68–S74.

Brunski JB (2003). Biomechanical aspects of oral/maxillofacial implants. Int J Prosthodont 16(Suppl):30–32.

Cattaneo PM, Dalstra M, Melsen B (2005). The finite element method: a tool to study orthodontic tooth movement. J Dent Res 84:428–433.

Davies SJ, Gray RJ, Linden GJ, James JA (2001). Occlusal considerations in periodontics. Br Dent J 191:597

Scortecci G, Misch C, Benner K. Implants and Restorative Dentistry. London:Martin Dunitz Ltd. 2001. pg59-87.

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